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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY  

Cobalt blue is one of the most chemically and thermally stable blue pigments. However, cobalt is scarce and expensive. To minimize the use of cobalt and reduce production costs and toxicity, cobalt blue core-shell pigments were synthesized by a solid-state method, which is cheaper than a liquid-phase reaction. Small cobalt hydroxide particles and large -alumina particles, in various ratios, were used as the starting materials. The dry mixed powders were calcined at 1200 degrees C for 2hours. Elemental mappings of the surfaces and cross sections of the synthesized particles showed that the cobalt blue had a core-shell structure. X-ray diffraction patterns showed that the synthesized cobalt blue consisted of an -alumina core and a cobalt aluminate shell. The color tone of the synthesized cobalt blue was evaluated from the lightness (L*) and chroma (C*) values. The color tone of the cobalt blue synthesized in this study was almost same as those of commercially available samples although the cobalt molar fraction was lower than the stoichiometric ratio (Co/(Co+Al)=0.33, Co/Al=0.5) which was calculated from the chemical reaction formula.

DOI： 10.1111/jace.16191

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Informa UK Limited  

DOI： 10.1080/01490451.2018.1550127

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The color tone of pigments is affected by various factors such as crystal structure and particle size. These characteristics should be determined by synthesis condition. In this study, the influence of cobalt source on the color tone of cobalt blue pigment was investigated. Cobalt blue (CoAl2O4) was synthesized by solid-state reaction method. Co3O4 and Co(OH)2 with two different particle sizes were used as the cobalt source, and γ-Al2O3 was used as the aluminum source. The products were characterized by spectrophotometry, XRD, SEM, and TG/DTA. It was revealed that the chroma of the synthesized cobalt blue depends on the cobalt source. The cobalt blue synthesized using smaller size Co(OH)2 showed most vivid color. It was suggested that the number of the contact points between the starting materials increased with decreasing the particle size, leading to the progress of the reaction.

DOI： 10.4164/sptj.56.446

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

Cathepsin K inhibitors are new drugs with the potential for the treatment of osteoporosis because they sustain bony remodelling better than bone resorption inhibitors such as bisphosphonates. The treatment of osteoporosis with inhibitors of bony resorption is associated with osteonecrosis of the jaw, as the deterioration in bony quality that they induce is thought to be one of its causes. The quality of bone is delineated by structural and material characteristics (which include the degree and quality of mineralisation, and depends on the content of proteoglycan and the structural integrity of the bony collagen).1,2 Animal and clinical studies have shown that cathepsin K inhibitors improve the mineral density and structural characteristics of bone, but their effect on the rest remains unknown. We therefore hypothesised that these inhibitors will affect the material characteristics of newly-formed mandibular bone. To verify our hypothesis, we used Raman microspectroscopy to examine such bone in rats that were given a cathepsin K inhibitor, and found unusual crystallinity and an increased substitution of carbonate (CO32-) in its crystal structure.

DOI： 10.1016/j.bjoms.2018.08.003

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Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.2497/jjspm.65.585

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

Bone quality is defined by structural and material characteristics. Most studies on the mandible have focused on the analysis of structural characteristics, with insufficient investigation of material characteristics. This study tested whether zoledronate affects the material characteristics of newly formed mandibular bone. Thirty-six female Wistar rats were assigned to three groups: sham-ovariectomized rats (SHAM, n=12), ovariectomized rats (OVX, n=12), and ovariectomized rats treated with zoledronate (ZOL, n=12). The left side of the mandibular ramus of all rats was drilled bicortically. Twenty-eight days after surgery, all surviving rats were euthanized and all mandibles were removed. Raman microspectroscopy was performed, and five spectra per specimen of newly formed mandibular bone were analysed. Compared with OVX rats, the mineral/matrix ratio in ZOL rats was significantly increased (5.43±1.88 vs. 7.86±2.05), while crystallinity (0.055±0.002 vs. 0.050±0.002), relative proteoglycan content (0.43±0.10 vs. 0.31±0.05), and collagen structural integrity (1.16±0.21 vs. 0.72±0.06) were significantly decreased. These changes in material characteristics may explain why rats that received zoledronate exhibited peculiar biological phenomena such as bisphosphonate-related osteonecrosis of the jaw.

DOI： 10.1016/j.ijom.2018.02.002

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.ijom.2018.

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier B.V.  

Cobalt blue is an inorganic pigment with an intense blue color, and consists mainly of cobalt aluminate (CoAl2O4) spinel. Many synthesis methods for cobalt blue have been reported, but there are no reports on the color tone of cobalt blue synthesized from different starting materials. Thus, the relationship between starting material and the color tone of the resulting product has not yet been clarified. We experimentally investigate the influence of different starting materials on the color tone of cobalt blue, synthesized by solid-state reaction. Cobalt oxide (Co3O4) was used as the cobalt source, and three types of aluminum source, Al(OH)3, γ-Al2O3, and α-Al2O3, were used. The color tone of cobalt blue was evaluated by the lightness L* and Chroma C* values, based on CIE L⁎a⁎b⁎ color coordinates. The properties of the products were characterized by spectrophotometry, X-ray diffraction, scanning electron microscopy (SEM), particle size distribution analysis, and thermal gravimetric-differential thermal analyses. SEM images and particle size distribution analysis revealed that the lightness L* value depends on the mass median diameter of the cobalt blue. The Chroma C* value is affected by the crystallinity of the aluminum source. These results suggest that the lightness L* and Chroma C* values of cobalt blue can be controlled by the particle size and crystallinity of the starting materials.

DOI： 10.1016/j.powtec.2016.06.021

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

Well-crystallized epitaxial YbFe2O4 films were prepared on an alpha-Al2O3(001) substrate using an Fe3O4 buffer layer. Fe3O4 has a relatively small lattice mismatch with both YbFe2O4 and alpha-Al2O3. Electron diffraction analysis combined with transmission electron microscopy revealed the epitaxial relationship to be alpha-Al2O3[110](001) parallel to Fe3O4[211](111) parallel to YbFe2O4[110](001). Moreover, superlattice spots due the Fe2+-Fe3+ charge order state of YbFe2O4 were clarified. The Fe2+/Fe3+ ratio in YbFe2O4 was nearly stoichiometric. The film exhibited a ferrimagnetic transition at similar to 220K and a nonlinear current-voltage characteristic at room temperature. These results confirmed the good crystallinity and stoichiometry of the obtained YbFe2O4 films. (C) 2018 The Japan Society of Applied Physics

DOI： 10.7567/JJAP.57.010305

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Society of Materials Science Japan  

DOI： 10.2472/jsms.66.799

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

Leptothrix species, aquatic Fe-oxidizing bacteria, excrete nano-scaled exopolymer fibrils. Once excreted, the fibrils weave together and coalesce to form extracellular, microtubular, immature sheaths encasing catenulate cells of Leptothrix. The immature sheaths, composed of aggregated nanofibrils with a homogeneous-looking matrix, attract and bind aqueous-phase inorganics, especially Fe, P, and Si, to form seemingly solid, mature sheaths of a hybrid organic inorganic nature. To verify our assumption that the organic skeleton of the sheaths might sorb a broad range of other metallic and nonmetallic elements, we examined the sorption potential of chemically and enzymatically prepared protein-free organic sheath remnants for 47 available elements. The sheath remnants were found by XRF to sorb each of the 47 elements, although their sorption degree varied among the elements: >35% atomic percentages for Ti, Y, Zr, Ru, Rh, Ag, and Au. Electron microscopy, energy dispersive x-ray spectroscopy, electron and x-ray diffractions, and Fourier transform infrared spectroscopy analyses of sheath remnants that had sorbed Ag, Cu, and Pt revealed that (i) the sheath remnants comprised a 5-10 nm thick aggregation of fibrils, (ii) the test elements were distributed almost homogeneously throughout the fibrillar aggregate, (iii) the nanofibril matrix sorbing the elements was nearly amorphous, and (iv) these elements plausibly were bound to the matrix by ionic binding, especially via OH. The present results show that the constitutive protein-free exopolymer nanofibrils of the sheaths can contribute to creating novel filtering materials for recovering and recycling useful and/or hazardous elements from the environment. (C) 2017 Published by Elsevier Ltd.

DOI： 10.1016/j.watres.2017.05.003

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Journal of the Japan Society of Powder and Powder Metallurgy  

Y-Type ferrite substituted with a combination of non-magnetic lithium and aluminum, Ba2Zn2-2xLixAlxFe12O22, was synthesized by polymerized complex method and the effects of substitution on their magnetic properties were investigated. The monophasic Y-Type ferrite was obtained at the composition range up to x = 0.6 and their lattice parameters decreased isotropically by the substitution. The saturation magnetization at 10 K decreased and Curie temperature increased with increasing composition x. As a result, the saturation magnetization at room temperature showed maximum at x = 0.2 and the relative complex permeability of sintered Y-Type ferrite also showed same tendency. The substituion with a combination of non-magnetic ions could enhanced the magnetic properties of Y-Type ferrite through lattice contraction and/or site occupation of iron ions.

DOI： 10.2497/jjspm.64.378

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCI LTD  

Polycrystalline powder samples of the zinc-substituted strontium cobalt Z-type hexaferrite: Sr3Co2-xZnxFe24O41 (x = 0, 0.5, 1.0, 1.5 and 2.0) were prepared by the polymerizable complex method. Their Mossbauer spectra were measured at room temperature with conventional constant-acceleration spectrometer. Obtained Mossbauer spectra were numerically separated into six discrete components. The relationship between Mossbauer parameters and magnetic properties has been discussed. From the values of the isomer shift, it was found that the iron ion in Sr3Co2-xZnxFe24O41 is trivalent with high spin. The value of the quadrupole splitting increased and changed the sign from negative to positive for the sample with x = 1.5. From the results mentioned above and the analysis of the complex permeability spectra, the magnetocrystalline anisotropy of Sr3Co2-xZnxFe24O41 is changed from c-plane to c-axis at Zn content between x = 1.0 and 1.5. The compositional dependence of the areas of each subspectra showed that Zn2+ ions occupy the sites with down spin at the compositional range of x = 0.0-1.0.

DOI： 10.1016/j.ceramint.2017.05.264

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

A high-capacity and high-rate-capability anode material for lithium-ion batteries, silicon-doped iron oxyhydroxide or 2-line ferrihydrite (2Fh), was prepared by mixing iron nitrate powder, tetraethyl orthosilicate, 2-propanol, and ammonium hydrogen carbonate powder at room temperature. The design of this material was inspired by a bacteriogenic product, a nanometric amorphous iron-based oxide material containing small amounts of structural Si. The atomistic structure of the prepared Si-doped 2Fh was strongly affected by the Si molar ratio [x = Si/(Fe + Si)]. Its crystallinity gradually decreased as the Si molar ratio increased, with a structural variation from nanocrystalline to amorphous at x = 0.25. The sample with x = 0.20 demonstrated the best Li storage performance. The developed material exhibited a high capacity of similar to 400 mAh g(-1) at the 25th cycle in the voltage range of 0.3-3.0 V and at a current rate of 9 A g(-1), which was three times greater than that of the Si-free 2Fh. This indicates that Si-doping into the 2Fh structure realizes good rate capability, which are presumably because of the specific nanocomposite structure of iron-based electrochemical centers embedded in the Si-based amorphous matrix, generated by reversible Li insertion/deinsertion process. (C) 2016 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jpowsour.2016.08.037

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER INST PHYSICS  

Rare-earth iron oxides (RFe2O4) have attracting attention as new electronic device materials because of their numerous functionalities, such as electronic ferroelectricity, ferrimagnetism, and high infrared absorption. In this paper, nearly monophasic YbFe2O4 films were prepared on alpha-Al2O3 (001) substrates by the spin coating method using an aqueous-based YbFe2O4 solution. The solution was composed of a stoichiometric ratio of Yb(CH3COO)(3) and Fe(NO3)(3) with excess chelating agents. After heat treatment above 800 degrees C, well-crystallized and highly (001)-oriented YbFe2O4 started to epitaxially form on the substrate under controlled oxygen partial pressure with H-2/CO2 gas mixtures. X-ray pole figure analysis confirmed the following epitaxial relationship: YbFe2O4[100](001)//alpha-Al2O3[100](001). Moreover formation of an Fe3O4 interracial layer between YbFe2O4 and alpha-Al2O3 was detected by high-resolution transmission electron microscopy. Presence of the Fe3O4 interracial layer seemed to release the lattice misfit with the substrate. The Fe2+/Fe3+ ratio in the obtained YbFe2O4 films was nearly stoichiometric and the indirect bandgap assigned to Fe2+ -> Fe3+ charge transfer excitation was found to be similar to 0.4 eV by optical spectroscopy. A clear magnetic transition from the paramagnetic state to the ferrimagnetic state occurred at similar to 230 K. (C) 2016 Author(s).

DOI： 10.1063/1.4961639

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SAGE PUBLICATIONS INC  

The interfacial interaction of veneering ceramic with zirconia is still not fully understood. This study aimed to characterize morphologically and chemically the zirconia-veneering ceramic interface. Three zirconia-veneering conditions were investigated: 1) zirconia-veneering ceramic fired on sandblasted zirconia, 2) zirconia-veneering ceramic on as-sintered zirconia, and 3) alumina-veneering ceramic (lower coefficient of thermal expansion [CTE]) on as-sintered zirconia. Polished cross-sectioned ceramic-veneered zirconia specimens were examined using field emission gun scanning electron microscopy (Feg-SEM). In addition, argon-ion thinned zirconia-veneering ceramic interface cross sections were examined using scanning transmission electron microscopy (STEM)-energy dispersive X-ray spectrometry (EDS) at high resolution. Finally, the zirconia-veneering ceramic interface was quantitatively analyzed for tetragonal-to-monoclinic phase transformation and residual stress using micro-Raman spectroscopy (mu Raman). Feg-SEM revealed tight interfaces for all 3 veneering conditions. High-resolution transmission electron microscopy (HRTEM) disclosed an approximately 1.0-mu m transformed zone at sandblasted zirconia, in which distinct zirconia grains were no longer observable. Straight grain boundaries and angular grain corners were detected up to the interface of zirconia-and alumina-veneering ceramic with as-sintered zirconia. EDS mapping disclosed within the zirconia-veneering ceramic a few nanometers thick calcium/aluminum-rich layer, touching the as-sintered zirconia base, with an equally thick silicon-rich/aluminum-poor layer on top. mu Raman revealed t-ZrO2 -to-m-ZrO2 phase transformation and residual compressive stress at the sandblasted zirconia surface. The difference in CTE between zirconia-and the alumina-veneering ceramic resulted in residual tensile stress within the zirconia immediately adjacent to its interface with the veneering ceramic. The rather minor chemical elemental shifts recorded in the veneering ceramic did not suffice to draw definitive conclusions regarding potential chemical interaction of the veneering ceramic with zirconia. Sandblasting damaged the zirconia surface and induced phase transformation that also resulted in residual compressive stress. Difference in CTE of zirconia versus that of the veneering ceramic resulted in an unfavorable residual tensile stress at the zirconia-veneering ceramic interface.

DOI： 10.1177/0022034515608825

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Inspired by a nanometric iron-based oxide material of bacterial origin, silicon (Si)-doped iron oxyhydroxide nanopartides or 2-line ferrihydrites (2Fhs) were prepared and their lithium (Li) storage properties were investigated. The structures of the Si-doped 2Fhs strongly depended on the Si molar ratio [x = Si/(Fe + Si)] whose longrange atomic ordering gradually vanished as the Si molar ratio increased, with a structural change from nanocrystalline to amorphous at x = 0.30. The most striking properties were observed for the sample with x = 0.30. Over the voltage range of 1.5-4.0 V at a current rate of 500 mA/g, this material exhibited a relatively high reversible capacity of similar to 100 mAh/g, which was four times greater than that of the Si-free 2Fh and indicated a good rate capability and cyclability. The large capacity and good rate and cycle performances are presumably because of the amorphous structure and the strong and stabilizing covalent Si-O bonds, respectively. The minor amount of Si4+ in the structure of the iron oxyhydroxides is considered to improve the electrochemical properties. Use of more appropriate doping elements and fabrication of more appropriate nanostructures could drastically improve the Li storage properties of the developed bioinspired material.

DOI： 10.1021/acs.inorgchem.5b01165

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

A bacterial siliceous iron oxide microtubule (diameter: ca. 1 mu m, 15Fe(2)O(3)center dot 8SiO(2)center dot P2O6 center dot 30H(2)O) produced by Leptothrbc ochracea was heat treated in air and its structural transformation was investigated in detail by microscopy, diffractometry, and spectroscopy. Although the heat-treated bacterial iron oxide retained its original microtubular structure, its nanoscopic, middle-range, and local structures changed drastically. Upon heat treatment, nanosized pores were formed and their size changed depending on temperature. The Fe O Si linkages were gradually cleaved with increasing temperature, causing the progressive separation of Fe and Si ions into iron oxide and amorphous silicate phases, respectively. Concomitantly, global connectivity and local structure of FeO6 octahedra in the iron oxide nanoparticles systematically changed depending on temperature. These comprehensive investigations clearly revealed various structural changes of the bacterial iron oxide which is an important guideline for the future exploration of novel bio-inspired materials. (C) 2015 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.matchemphys.2015.01.067

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Lithium-ion discharge/charge properties of a nanometric amorphous iron-based oxide material of bacterial origin, L-BIOX, in a voltage range of 1.5-4.0 V were studied. X-ray absorption fine structure measurements confirmed that Fe3+ -><- Fe2+ reactions dominate in this voltage range. Cycle characteristics with a capacity exceeding 70 mAh/g at a current rate of 1670 mA/g are considerably higher than those achieved by known simple iron-oxides such as alpha-Fe2O3. (C) 2014 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.matlet.2014.10.126

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Inspired by the traditional Japanese pigment Fukiya bengala, nanocomposite materials were synthesized using a polymer complex method, comprising Al-substituted a-Fe-2O3 (hematite) particles with diameters ranging from 40 to 100 nm and ultrafine Fe-substituted a-Al2O3 (corundum) particles smaller than 10 nm in diameter. The obtained powders exhibited a vivid yellowish-red color and high thermostability, making them attractive as potential overglaze enamels on porcelain. Quantitative color measurements revealed that, when heated to 700, 800, and 900 degrees C, samples displayed high lightness (L*) and color-opponent dimensions (a* and b*) at 10 mol % Al. For the same particle size samples, L*, a*, and b* values increased with the Al molar ratio, revealing that Al substitution in the hematite structure intrinsically enhances lightness and chroma in hematite color. These samples mostly retained their color upon reheating at 900 degrees C, indicating their high thermostability. This thermostability should originate from the Al substitution-induced enhancement in lightness and chroma in hematite color, which should counter color fading caused by particle growth. These composite materials are expected to find application in the porcelain industry, cosmetics, and nanotechnology.

DOI： 10.1021/am505820b

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Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.4164/sptj.51.629

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：SPRINGER  

Ilmenite-type FeGeO3 was prepared by high-pressure synthesis technique using a Kawai-type multi-anvil apparatus at 23.5 GPa and 500 A degrees C. The effects of post annealing on the high-pressure synthesized samples were investigated by XRD analysis, Mossbauer spectroscopy and SQUID-magnetization measurements. The subsequent annealing after the high-pressure synthesis was effective to improve the crystallinity and increased the crystallite size of the ilmenite-type FeGeO3. The room temperature Mossbauer spectrum was composed of sharp paramagnetic doublets assigned to Fe2+. The well-crystallized ilmenite-type FeGeO3 showed typical antiferromagnetic behavior with the N,el temperature of 79 K, while the as-prepared sample without annealing demonstrated the superparamagnetic characteristics with larger magnetization.

DOI： 10.1007/s10751-014-1014-y

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Other Link： http://orcid.org/0000-0002-5422-7396

Language：English   Publishing type：Research paper (scientific journal)  

We prepared nano-micrometer-architectural acidic silica from a natural amorphous iron oxide with structural silicon which is a product of the iron-oxidizing bacterium Leptothrix ochracea. The starting material was heat-treated at 500 C in a H2 gas flow leading to segregation of α-Fe crystalline particles and then dissolved in 1 M hydrochloric acid to remove the α-Fe particles, giving a gray-colored precipitate. It was determined to be amorphous silica containing some amount of iron (Si/Fe = ∼60). The amorphous silica maintains the nano-microstructure of the starting material - ∼1-μm-diameter micrometer-tubules consisting of inner globular and outer fibrillar structures several tens of nanometer in size - and has many large pores which are most probably formed as a result of segregation of the α-Fe particles on the micrometer-tubule wall. The smallest particle size of the amorphous silica is ∼10 nm, and it has a large surface area of 550 m2/g with micropores (0.7 nm). By using pyridine vapor as a probe molecule to evaluate the active sites in the amorphous silica, we found that it has relatively strong Brønsted and Lewis acidic centers that do not desorb pyridine, even upon evacuation at 400 C. The acidity of this new silica material was confirmed through representative two catalytic reactions: ring-opening reaction and Friedel-Crafts-type reaction, both of which are known to require acid catalysts. © 2013 American Chemical Society.

DOI： 10.1021/am401029r

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Language：English   Publishing type：Research paper (scientific journal)  

To develop novel magnetic composites with acid functionalities, iron oxide produced by iron-oxidizing bacterium, Leptothrix ochracea, was used as a precursor. The composites were prepared by thermal treatment and subsequent reduction of the bacterial iron oxide. α-Fe2O3 nanoparticles obtained in air were thermally reduced to Fe3O 4 and gradually oxidized to γ-Fe2O3. The obtained composites with Fe3O4 and γ-Fe 2O3 have high magnetization values that are approximately half those of pure Fe3O4 and γ-Fe2O 3. All samples have an interesting nano-micro-architectural structure: ∼40-nm-diameter crystalline particles covered with ∼8-nm-thick amorphous silicate are intricately interconnected into ∼1-μm-diameter microtubules. Pyridine adsorption spectra indicate that the surface amorphous silicate has both Brönsted and Lewis acid properties. © 2012 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.materresbull.2012.12.022

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

beta-Fe2O3 is the scarce polymorph of Fe2O3 phases and is transformed easily into alpha-Fe2O3 at high temperature. However, its crystal structure and the transformation, mechanism to alpha-Fe2O3 are still unclear because of the difficulty in obtaining monophasic beta-Fe2O3 crystals. We established a synthesis method of the monophasic beta-Fe2O3. It was synthesized by a two-step reaction: heating a mixture of Na2SO4 and Fe-2(SO4)(3) in air at 250 degrees C to form NaFe(SO4)(2), and subsequent heating the resultant phase with NaCl in air at 500 degrees C. The crystal structure was refined to a bixbyite-type cubic structure (Ia (3) over bar) with alpha = 9.4039(1) angstrom by the Rietveld method. Single crystalline beta-Fe2O3 particles of approximately 1 mu m in size were topotactically transformed into single alpha-Fe2O3 crystals. Electron diffraction analysis revealed the crystallographic orientation relationships between beta-Fe2O3 and alpha-Fe2O3 to be [100](beta)//[0001](alpha), [010](beta)//[10 (1) over bar0](alpha), and [001](beta)//[(1) over bar2 (1) over bar0](alpha).

DOI： 10.1021/cg301493a

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ACADEMIC PRESS INC ELSEVIER SCIENCE  

We synthesized well-crystallized ilmenite-type FeGeO3 to investigate its structural and magnetic properties. Ilmenite-type FeGeO3 were synthesized by high-pressure synthesis technique using a Kawai-type multi-anvil apparatus. Their structural and magnetic properties were examined by XRD analysis with Rietveld refinement, transmission electron microscopy, Mossbauer spectroscopy and SQUID-magnetization measurements. The subsequent annealing after the high-pressure synthesis was effective to improve the crystallinity of the ilmenite-type FeGeO3. The primary particle size of ilmenitetype FeGeO3 was similar to 15 nm. Some particles seemed to be covered with non- or poorly crystalline phase even after the annealing, and others showed a lamellar microstructure parallel to the (0 0 1) plane. Theilmenite-type FeGeO3 showed typical antiferromagnetic behavior with the Neel temperature of 79 K. (c) 2012 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.jssc.2012.11.020

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Microporous and mesoporous silica derived from biogenous iron oxide is an attractive catalyst for various organic reactions. Biogenous iron oxide contains structural silicon, and amorphous silica remains after iron oxide is dissolved in concentrated hydrochloric acid. The amorphous silica containing slight amounts of iron (Si/Fe = similar to 150) is composed of similar to 6-nm-diameter granular particles. The amorphous silica has a large surface area of 540 m(2)/g with micropores (1.4 nm) and mesopores (<3 nm). By using pyridine vapor as a probe molecule to evaluate the active sites in the amorphous silica, it was found that this material has strong Bronsted and Lewis acid sites. When the catalytic performance of this material was evaluated for reactions including the ring opening of epoxides and Friedel Crafts-type alkylations, which are known to be catalyzed by acid catalysts, this material showed yields higher than those obtained with common silica materials.

DOI： 10.1021/am302837p

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：TRANS TECH PUBLICATIONS LTD  

Synthesis of Sr3Zn2Fe24O41 Z-type ferrite was investigated. Precursors of ferrite were prepared by polymerizable complex method. Identification of formed phases in the obtained samples and determination of lattice parameters of Z-type ferrite were performed by powder X-ray diffraction (XRD). Single-phase of Sr3Zn2Fe24O41 Z-type ferrite was synthesized by heating at 1463 K for 5hours in air. M-H curve of prepared single-phase Sr3Zn2Fe24O41 Z-type ferrite was measured by using vibrating sample magnetometer (VSM). It was revealed that Sr3Zn2Fe24O41 Z-type ferrite has larger saturation magnetization (23.5 mu(B)/formula unit) than that of Sr3Co2Fe24O41 (22.7 mu B/formula unit) and shows characteristic two-step saturation of magnetization as well as Sr3Co2Fe24O41 Z-type ferrite.

DOI： 10.4028/www.scientific.net/KEM.566.231

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：TRANS TECH PUBLICATIONS LTD  

Synthesis of U-type hexaferrite was investigated in the various strontium-based systems (Sr-Me-Fe-O system, Me = Co, Zn, Cu, and Ni). Precursors of ferrites were prepared by polymerizable complex method. Sr4Me2Fe36O60 (Me = Co and Zn) U-type hexaferrites were synthesized at the temperature range between 1423 and 1483 K in air. Coercivity of obtained ferrite was decreased with increasing heat treatment temperatures. Cu substitution reduced formation temperature of U-type hexaferrite.

DOI： 10.4028/www.scientific.net/KEM.566.227

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Language：Japanese   Publisher：Japan Society of Powder and Powder Metallurgy  

In the natural aquatic environment, there are various types of biogenic manganese oxide (BMO) precipitates which are produced by manganese oxidizing microorganisms, at ambient temperature, atmosphere and neutral pH.BMO is a very interesting and useful functional material because of its unique property; hollow globule shape formed by nanosheets, large surface area and photocatalytic characteristics. In this study, thermally-processed BMO at 100 − 1000 °C was analyzed by XRD, XANES, SEM, TEM and nitrogen adsorption method to reveal the effects of heat-treatment on its crystal structure, Mn valence state, globule morphology, microstructure, pore size distribution and specific surface area. In the result, morphology of BMO is maintained below 800 °C, while nanosheets composing BMO were changed into nanoparticles at 600 °C. The crystal structure was transformed from birnessite into hausmannite (Mn₃O₄) at 600 °C. The specific surface area was increased by heat-treatment between 300 and 500 °C. In cases of artificial manganese oxides, such changes of crystal structure and specific surface area were not observed, and combustion of organic materials produced by microorganisms in BMO probably has a large effect on them.

DOI： 10.2497/jjspm.60.92

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Powder and Powder Metallurgy  

To clarify the detailed features of the red bengala samples excavated from the Shimo-ohgibaru archaeological site in the late Yayoi period (2^nd to 3^rd century A.D.) from the viewpoint of materials science, colorimetric measurements, X-ray fluorescence analyses, X-ray diffraction measurements, transmission electron microscope observations, and surface area measurements of the ancient bengala samples were achieved. The ancient bengala sample was found to be high purity α - Fe₂O₃. The features of the color tone and particle size of the ancient bengala were clarified by comparing with those of commercially available bengala, Fukiya bengala, and synthesized α-Fe₂O₃. In addition, the starting materials and synthesis processes of the ancient bengala were discussed by applying the elutriation experiments of representative natural hematite and heat-treated natural iron hydroxide (Oniita).

DOI： 10.2497/jjspm.60.146

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

In nature, there are various iron oxides produced by the water-habitant bacterial group called "iron-oxidizing bacteria". These iron oxides have been studied mainly from biological and geochemical perspectives. Today, attempts are made to use such iron oxides as novel functional materials in several applications. However, their quantitative structural characteristics are still unclear. We studied the structure of iron oxide of microtubular form consisting of amorphous nanoparticles formed by an iron-oxidizing bacterium, Leptothrix ochracea, using a combination of high-energy X-ray diffraction and reverse Monte Carlo simulation. We found that its structure consists of a framework of corner- and edge-sharing distorted FeO6 octahedral units, while SiO4 tetrahedral units are isolated in the framework. The results reveal the atomic arrangement of iron oxide of bacterial origin, which is essential for investigating its potential as a functional material. (C) 2012 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.matchemphys.2012.10.002

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By heating an amorphous iron oxide produced by Leptothrix ochracea, an iron-oxidizing bacterium species, at 600-1100 degrees C in air for 2 h, vivid red-colored powdered materials including alpha-Fe2O3 (hematite) and amorphous silicate with high thermostability were prepared which offer potential for use as over-glaze enamels on porcelain. The precise color tone of the materials greatly depends on the heat-treatment temperature. The most strikingly beautiful sample, heat-treated at 800 degrees C, is light yellowish-red in color (L* = 47.3, a* = 34.1, and b* = 34.6), has a unique microstructure, and does not fade in color even with reheating at 800 degrees C, which is the firing temperature for over-glaze enamel on porcelain. The sample primarily consists of crystalline hematite particles similar to 40 nm in diameter with slightly longer axis unit-cell parameters than those of pure hematite. The particles are covered with amorphous silicate phase similar to 5 nm in thickness and are intricately interconnected into microtubules with an average diameter of 1.26 mu m. The attractive color of this material is due to the following structural features: small particle size (similar to 40 nm). nanocomposite of hematite and amorphous silicate, and a microtubule structure that inhibits aggregation of individual hematite particles and microtubules. (C) 2012 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.dyepig.2012.06.024

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Magnetic nanocomposites containing magnetite (Fe3O4) nanoparticles were prepared from iron oxide microtubules produced by Leptothrix ochracea, a species of water-habitant iron-oxidizing bacteria. The microtubules were mainly composed of Si-containing ferric hydroxide that shows a broad X-ray diffraction pattern similar to that of 2-line ferrihydrite. After moderate heat treatment in a reductive atmosphere above 325 degrees C, the ferric ions were partially reduced to a ferrous state, and nanocrystalline Fe3O4 with a spinel-type structure was formed in a noncrystalline silicate matrix. The average crystallite size of the Fe3O4 nanoparticles was estimated to be in the order of a few nanometers. The sample heat-treated at 500 degrees C exhibited considerable magnetization together with superparamagnetic behavior at room temperature, and super-spin-glass interaction occurred at low temperature. On further heat treatment above 530 degrees C, Fe3O4 was reduced to wustite (Fe1-xO) and finally crystallized into iron metal (alpha-Fe) and ferrous silicate (Fe2SiO4). (c) 2012 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.matchemphys.2012.08.070

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Powder and Powder Metallurgy  

Formation mechanism of β-Fe₂O₃ particles was investigated by controlling the preparation conditions such as the mixing ratio of NaFe(SO₄)₂ and Na₃Fe(SO₄)₃ to NaCl and the heat treatment temperature. The heat treatment temperature strongly affected the particle shapes and sizes. β-Fe₂O₃ was found to be formed by two different reactions; one is a solid state reaction below 490 °C, and another is a liquid phase-mediated reaction above 490 °C. β-Fe₂O₃ had granular shape with a diameter of about 50 to 100 nm below 490 °C, while at high temperatures above 490 °C cubic particles with relatively large size of about 500 nm to 2 μm were produced. We found that this dramatically change of particle morphology including their sizes and shapes was caused by the effects of the liquid phase in the reaction.

DOI： 10.2497/jjspm.58.529

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：SPRINGER  

Formation of LaFeO3 nanoparticles obtained from thermal decomposition of organometallic precursors was investigated as a function of the heat-treatment temperature. The precursors heat-treated below 300 degrees C were amorphous, but above 350 degrees C a single-phase of nanocrystalline LaFeO3 was formed. The LaFeO3 nanoparticles showed the superparamagnetic behavior in both magnetization and Mossbauer measurements. With increasing heat-treatment temperature, the crystallite size of LaFeO3 nanoparticles was gradually increased. The quadrupole splitting and isomer shift of paramagnetic doublet pattern were affected by the growth of LaFeO3 particles.

DOI： 10.1007/s10751-011-0423-4

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CERAMIC SOC JAPAN-NIPPON SERAMIKKUSU KYOKAI  

The microstructure and conditions for the formation of the reddish color referred to as hi-iro on Japanese ceramics were investigated through model experiments. The hi-iro marking was found to be formed by the reaction between clay and alkali ions supplied from the glaze. When a mixture of porcelain clay and 20 wt % KCl was heated in air at 1250 degrees C and then cooled slowly to 800 degrees C, hi-iro clearly appeared on the sample surface. In hi-iro, corundum [alpha-(Al,Fe)(2)O-3], hematite (alpha-Fe2O3) and a liquid phase are formed. Upon heating until 1250 degrees C, corundum is firstly precipitated as hexagonal plate-like crystals. During the cooling process, hematite precipitates on the edges of the corundum crystals to form specific composite particles. When rapidly cooled from 1250 degrees C to room temperature, a brownish red color appeared on the sample surface, which was found to be caused by the formation of approximately 50 mu m Al-substituted hematite (Fe1.9Al0.1O3) particles. The relationship between the microstructure of the phases formed and the color is discussed. (C)2011 The Ceramic Society of Japan. All rights reserved.

DOI： 10.2109/jcersj2.119.942

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

Nanocrystalline LaFeO3 particles were synthesized at low temperatures by using hot soap technique. The synthesis was based on the thermal decomposition of organometallic compounds precipitated in a hot coordinating solvent. Moderate heat treatment at low temperature far below the combustion point of organic compounds produced spherical LaFeO3 nanoparticles with average diameter of about 15 nm. The crystalline phase, structure and particle size of obtained products were characterized by Xray diffraction, infrared spectroscopy and transmission electron microscopy observations. In spite of the antiferromagnetic nature of bulk LaFeO3, the obtained nanoparticles exhibited anomalous large magnetization. Superparamagnetic behavior with a blocking temperature of about 30 K was observed in both magnetization and Mossbauer spectroscopic analyses. (C) 2011 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.matchemphys.2011.05.015

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Synthesis of single-phase Sr3Co2Fe24O41 Z-type (Sr(3)CO(2)Z) ferrite was realized by adopting the polymerizable complex method. Crystal structure of samples has been investigated by powder X-ray diffraction (XRD). Single-phase Sr(3)Co(2)Z ferrite was obtained by heating at 1473 K for 5 h in air. Magnetic properties were discussed by measurements of M-H curves with vibrating sample magnetometer (VSM). Sr(3)CO(2)Z ferrite prepared by polymerizable complex method showed typical M-H curve of soft ferrite, with a saturation magnetization of 21.5 mu(B)/formula unit (50.5 emu/g) and a coercive force of 0.0141 at room temperature. (C) 2011 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.materresbull.2011.03.004

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IOP PUBLISHING LTD  

Synthesis of La-Co substituted M-type Calcium hexaferrite was studied. Samples were prepared by polymerizable complex method. High purity reagent of strontium carbonate, iron (III) nitrate ennnahydrate, cobalt (II) nitrate hexahydrate and lanthanum oxide were used as starting materials. Prepared aqueous solution was heated for dehydration and gelling. Thermal pyrolysis was carried out by heating the gel. The obtained precursor powders were ground with an alumina mortar and compacted by uniaxial pressing into disk specimens and then heated at temperature range between 1173 K and 1573 K in air. Phase identification and determination of lattice parameters were carried out by powder X-ray diffraction (XRD). Scanning Electron Microscope (SEM) was utilized to investigate the microstructure of the polycrystalline ferrites. Magnetic properties were discussed by magnetization measurements by measuring of M-H curve with vibrating sample magnetometer (VSM). Single-phase of M-type hexaferrite was obtained at lower temperature relative to by conventional synthesis.

DOI： 10.1088/1757-899X/18/9/092040

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Magnetic properties of La-Co substituted M-type strontium hexaferrites were studied. The samples were prepared by polymerizable complex method. Crystal structure of samples has been investigated by powder X-ray diffraction (XRD). Single-phase M-type strontium hexaferrites with chemical composition of Sr(1.05-x)La(x)Fe(12-x)Co(x)O(19) (x = 0-0.4) were formed by heating at 1173 K for 24 h in air. Magnetic properties were discussed by measurements of M-H curves with vibrating sample magnetometer (VSM). La-Co substituted M-type strontium hexaferrites prepared by polymerizable complex method showed typical magnetic hysteresis of hard ferrite. The coercive force increased significantly by La-Co substitution with polymerizable complex method. Maximum coercive force achieved in this study is 8.0 kOe (640 kA/m). Scanning electron microscopy revealed that the prepared ferrite particles have plate-like shape of diameter range between 20 and 500 nm. (C) 2010 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jmmm.2010.02.041

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

The biogenous iron oxide (BIO) from Leptothrix ochracea was transformed to an organic-inorganic hybrid support to prepare an excellent immobilized enzyme showing high catalytic performance.

DOI： 10.1039/b919497e

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Formation mechanism of nano-crystalline beta-Fe(2)O(3) particles was investigated by controlling the preparation conditions such as the mixing ratio of NaFe(SO(4))(2) to NaCl and heating treatment temperature. A single phase of beta-Fe(2)O(3) was formed regardless of the mixing ratio. The heat treatment temperature strongly affected the particle shapes and sizes. Below 490 degrees C, they had granular shape with a diameter of about 50 to 100 nm. While, above 490 degrees C, cubic particles with increased size of about 1 mu m were produced. All samples were antiferromagnetic at low temperature. The Neel temperature (T(N)) of 119 K for the large cubic particles was decreased to 113 K for the nanoparticles.

DOI： 10.1088/1742-6596/200/8/082003

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Ilmenite (FeTiO3) is an antiferromagnetic insulator with Neel temperature (T-N) of 55 K. The magnetic structure of FeTiO3 is known to be easily frustrated by cation substitution. In the present study we tried to prepare the Ge-substituted FeTiO3. The samples were prepared by the conventional solid state reaction technique under the controlled oxygen pressure. Formation of a single phase of FeTi1-xGexO3 with x=0.01 was confirmed by x-ray diffraction (XRD) method. The Ge-substituted FeTiO3 had a smaller lattice volume than that of un-doped one. SQUID magnetometer and Mossbauer spectroscopy measurements indicated that the Ge-substitution reduced the T-N slightly. Moreover the magnetic hyperfine fields of Ge-substituted FeTiO3 seemed to be increased in spite of the decreased magnetic moments.

DOI： 10.1088/1742-6596/200/1/012144

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Solid solutions between ilmenite (FeTiO3) and hematite (alpha-Fe2O3) are one of the candidates for high-temperature magnetic semiconductors. Well-crystallized epitaxial xFeTiO(3)-(1-x)Fe2O3 (0.5<x<1) films were prepared on both alpha-Al2O3(001) and (110) single-crystalline substrates by reactive sputtering technique. The (110)-oriented films provided more restricted preparation conditions than the (001)-oriented ones. Both films with x<0.7 had large saturation magnetization at room temperature. The magnetic easy plane lay in the (001) crystallographic plane regardless of the film orientations. The magnetic properties of (001)- and (110)-oriented films seemed to be affected not only by the crystalline orientation but also by the lattice strains induced in the films.

DOI： 10.1088/1742-6596/200/7/072029

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL PUBLISHING, INC  

The effects of oxygen partial pressure during thermal treatment on the color and microstructure of Bizen, a traditional Japanese stoneware, were studied through model experiments using clay pellets covered lightly with rice straw as a coloring assistant. When heated in flowing nitrogen, the model pellet turned blackish owing to the formation of alpha-Fe particles coated with graphite. However, schreibersite (Fe(3)P), which is also blackish, was formed specifically on the pellet surface in direct contact with the straw. The rice straw seems to have generated a strongly reducing atmosphere, strong enough for the metallization to alpha-Fe, and also to have provided phosphorus through contact. When oxygen content in the surrounding gas atmosphere was raised to N(2)/O(2)=99/1, the pellet surface turned yellowish brown because the main coloring material was Fe(3+)-containing mullite. At oxygen contents of N(2)/O(2)=98/2 or more, the formation of hematite (alpha-Fe(2)O(3)) pushed the color to deep red.

DOI： 10.1111/j.1551-2916.2009.03125.x

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER INST PHYSICS  

Thin films of ilmenite-hematite solid solution 0.6FeTiO(3)center dot 0.4Fe(2)O(3) were prepared on alpha-Al(2)O(3) (001) and (110) single-crystalline substrates. The oxide phases formed in the thin films strongly depended on the oxygen partial pressure (P(O2)) during deposition. At P(O2)=1.3x10(-3) Pa, regardless of thesubstrate orientation, well-ordered 0.6FeTiO(3)center dot 0.4Fe(2)O(3) films with R3 symmetry were epitaxially formed. Large saturation magnetization at room temperature was observed in both (001)- and (110)-oriented films. The differences in the magnetization and electrical resistivity curves between the (001)- and (110)-oriented films indicated the anisotropic nature of 0.6FeTiO(3)center dot 0.4Fe(2)O(3). (c) 2008 American Institute of Physics.

DOI： 10.1063/1.2951589

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Language：Japanese   Publisher：Japan Society of Powder and Powder Metallurgy  

In this study, thermal decomposition of Hinoki chips soaked in Ca solution and adsorption properties of obtained charcoal for nitrate nitrogen were investigated to develop a novel functional charcoal. Ca(OH)₂ was used as Ca source due to less environmental load and easy handling and Ca-impregnated chips were heat-treated in an electric muffle furnace at temperatures between 600 and 900°C. The Ca-loaded charcoal acid-treated with HCl exhibited adsorptive ability for nitrate nitrogen. It was revealed that adsorption of nitrate nitrogen was ion-exchange reaction and that the charcoal samples acid-treated with HCl could be regenerated repeatedly by exchanging nitrate ion for chloride ion. The measurements of adsorption properties for nitrate nitrogen revealed that the adsorptive ability and durability of these samples were higher than those of activate carbon and anion-exchange resin. It was also found the obtained charcoal exhibited selective adsorption for nitrate nitrogen and fluoride anion, but not for sulfuric acid and phosphoric acid anions. As the result, the simple method, Ca-impregnation, thermal decomposition and acid treatment of wood waste, has advantages in production of nitrate nitrogen adsorption material.

DOI： 10.2497/jjspm.55.177

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Language：Japanese   Publisher：Japan Society on Water Environment  

In recent years, the nitrate nitrogen pollution in lakes, rivers and underground water has become a serious issue. A new purification method for nitrate nitrogen is required, because no efficient means of purification has been established yet. Carbonization processing is one of the techniques of effectively using wood biomass. The obtained charcoal is widely used for a variety of purposes such as water purification and humidity control, and as a soil conditioner. However, the charcoal obtained by mere carbonization is expected to have limited uses. Thus, we have studied charcoal with the ability to absorb nitrate nitrogen. In this paper, we examined charcoal produced by soaking wood chips in CaCl₂ aq. solution, followed by carbonization and acid treatment with HCl. It was found that the obtained charcoal had the ability to absorb nitrate nitrogen and fluoride anion but not sulfate and phosphate anions. The adsorption ability could be recovered again by soaking in KCl aq. solution. As a result, it is expected that the charcoal obtained by this method can contribute to the purification of water polluted with nitrate nitrogen and to the effective use of wood biomass.

DOI： 10.2965/jswe.31.47

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

The influence of composition on the structural ordering and magnetism in the VxNb1+yS2 system has been investigated by X-ray diffraction and magnetic measurements. Stoichiometric V1/3NbS2 did not exhibit the structural ordering of vanadium between the NbS2 layers. In the ordered structure, the vanadium composition deviated from the ideal value of x = 1/3 to both higher and lower values, while the niobium composition was in the range of 0.05 <= y <= 0.18. Excess niobium, y > 0, is thought to play an essential role in the structural ordering in this system. For samples with excess niobium and ordered structures, a magnetic transition was observed at 20-50 K, depending on the composition. The spontaneous magnetization of 3-5 x 10(-3) mu(B)/V atom is thought to be intrinsic to this system. The magnetization curves consisted of a constant and a proportional parts of the magnetic field, which correspond to the spontaneous magnetization and high-field susceptibility, respectively. The magnetization curves and the temperature dependencies of the high-field susceptibility were quite similar to those of the canted antiferromagnetic NiS2. A correlation between the structural and magnetic ordering is suggested. (C) 2007 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.jpcs.2007.07.124

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An ilmenite-hematite solid solution (Fe2-x Tix O3) is one of the candidates for practical magnetic semiconductors with a high Curie temperature. We have prepared well-crystallized epitaxial Fe2-x Tix O3 films with a wide range of Ti concentrations- x=0.50, 0.60, 0.65, 0.76, 0.87, and 0.94-on α -Al2 O3 (001) substrates. The films are prepared by a reactive helicon plasma sputtering technique to evaporate Fe and TiO targets simultaneously under optimized oxygen pressure conditions. The structural characterizations of the films reveal that all films have a single phase of the ordered structure with R 3- symmetry, where Ti-rich and Fe-rich layers are stacked alternately along the c axis. All films have large ferrimagnetic moments at low temperature, and room temperature magnetization is clearly observed at x<0.7. The inverse temperature dependence of the resistivities of the films indicates their semiconducting behavior. The film resistivities decrease with decreasing Ti concentration. © 2008 American Institute of Physics.

DOI： 10.1063/1.2966298

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Well-crystallized epitaxial FeTiO3+delta films were prepared on the sapphire substrate by reactive sputtering technique. A wide range of oxygen nonstoichiometry from FeTiO3 to FeTiO3.5 was successfully controlled by controlling the sputtering conditions. All films had uniform structure without phase separation even for the highly oxidized FeTiO3.5 film. Structures, magnetic and electronic properties of the FeTiO3+delta films were seriously influenced by the oxygen nonstoichiometry. The nearly stoichiometric FeTiO3 films had a R (3) over bar structure, while the nonstoichiometric FeTiO3.5 had a R (3) over bar c structure. With increasing the oxygen nonstoichiometry, the valence states of Fe ions in FeTiO3+delta were examined to be changed from Fe2+ to Fe3+ by means of both Mossbauer and XPS spectroscopy. The Ti 2p core-level XPS spectra clearly confirmed the valence states of Ti4+ ions in nonstoichiometric FeTiO3.5. However the Ti ions in stoichiometric FeTiO3 suggested the abundant electron density than the conventional Ti4+ ions due to the Fe2+ to Ti4+ intervalence charge transfer.

DOI： 10.1088/1742-6596/100/1/012043

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Language：Japanese   Publisher：Japan Society of Powder and Powder Metallurgy  

Carbonization of wood waste contributes to prevention of global warming through carbon fixation and the obtained charcoal can be effectively used for environmental purification. However it is not expected the charcoal obtained by mere carbonization has various uses. In this study, thermal decomposition of chips of Japanese cypress soaked in Ca solution and absorption properties of obtained charcoal for hydrogen chloride gas were investigated to develop a novel functional charcoal. Ca(OH)₂ was used as Ca source due to less environmental load and easy handling. Ca-impregnated chips were heat-treated in an electric muffle furnace at temperatures between 600 and 900°C. The fine calcite crystals were dispersed homogeneously on the surface of tracheids in the heat-treated samples. The measurements of absorption properties for hydrogen chloride gas revealed that the absorptive ability and durability of these samples were higher than those of the conventional materials. From these results, it was suggested that an acidic gas absorption material with high reactivity could be prepared simply by the thermal decomposition of wood waste soaked in Ca solution.

DOI： 10.2497/jjspm.54.699

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

Single-phases of Pb-substituted Bi-Ca-Co-O misfit-layer cobaltites with various Pb concentrations have been synthesized and the Pb-substitution effects on the structural, electrical and magnetic properties have been systematically investigated. Powder X-ray diffraction analysis showed that the single-phases of Bi1.8-x/2PbxCa2Co2Oz were obtained up to x = 0.6-0.7 under the optimized synthesis conditions. The lattice parameters of Bi1.8-x/2PbxCa2Co2Oz continuously changed with increasing Pb concentration. The electron diffraction analysis suggested that the structure consisted of two different sublattices with a rock salt structure (RS) and a hexagonal CdI2 structure (H), respectively, without modulation. In combined with the chemical composition analysis, the chemical formulas of the x = 0 and x = 0.6 samples were determined approximately as [Bi1.74Co0.31Ca2.01O4](RS)[CoO2](1.69) and [Bi1.47Pb0.38Co0.29Ca1.98O4](RS)[CoO2](1.71), respectively. The electrical resistivity became more metallic with increasing the Pb concentration up to x = 0.6. Moreover, the Pb-substitution simultaneously increased the antiferromagnetic Weiss temperatures and decreased the effective magnetic moments of the Co ions. (C) 2006 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.ssc.2006.10.015

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：THE CARBON SOCIETY OF JAPAN  

We have prepared Carbon/Fe-Ni-Cu ternary alloy composites by polymerized complex method. A single-phase Fe-Ni-Cu alloy could be obtained in carbon matrix by controlling pH of the citrate complex solution. It was revealed that the chemical compositions of metals in composites were maintained well by adding ethylene glycol into the complex solution. Crystallinity of both carbon matrix and Fe-Ni-Cu alloy particles were enhanced with increasing the carbonized temperature. The composite carbonized at 700°C had larger saturation magnetization and smaller coercivity than that carbonized at 500°C, which correlated with metal content and crystallite size of alloy. The composite carbonized at 700°C exhibited larger permeability and permittivity than carbon/Fe-Co alloy composites at frequency of GHz range.

DOI： 10.7209/tanso.2007.158

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The ilmenite-hematite solid-solution, xFeTiO3-(1-x) α-Fe2O3 samples with x=0.7-1.0. were prepared by standard solid state reaction technique in an evaculated quartz tube. The sample pellets were heated at 1200°C for 24 hr, then furnance cooled to room temperature1. All samples consisted of a single phase of ilmenite structure. Lattice parameters of these samples estimated from the XRD patterns varied linearly with decreasing the Ti concentration on the basis of the Vegard&#039;s law. The saturating magnetization at 78 K was obtained at x=0.8 (Fe1.2Ti0.8O3), and the sample with x=0.7 (Fe1.3Ti0.7O3) was ferrimagnetic at room temperature. The carrier type measured by Seebeck coefficient was changed from p-type to n-type at about x=0.78 with decreasing the Ti concentration. Electronic states of Fe and Ti ions in FeTiO3 seemingly had the characteristic features of Fe2+ and Ti4+ respectively. However the Ti 2p→3p resonant valence band photoemission spectra of FeTiO3 had a clear density assigned to the Ti 3 d derived states. The small density appeared just below the Fermi edge was intrinsic for the FeTiO3 crystals because of identical x-ray absorption spectrum at Ti L2,3 edges between constant initial state and total electron yield mode.

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Ferroxplana type hexagonal ferrite with composition Ba2Co2Fe12O22 (CO2Y) was prepared by polymeric sol-gel method from the aqueous solution of their corresponding metal salts. All the samples were characterized by using X-ray diffraction and scanning electron microscopic technique. The formation and the microstructure of the Ba2Co2Fe12O22 was studied as a function of heat treatment temperature and it was observed that well defined hexagonal plate-like fine particles with particle sizes between 130 and 400nm were formed at relatively lower temperature (900 degrees C) as compared to conventional solid state reaction method (1100 degrees C). Magnetic properties of the samples were also studied as a function of heat treatment temperature and it showed large saturation magnetization (M-s) ranging from 30.9 to 47.6 emu/g and a wide range of coercivity (130-1566Oe) depending on the heat treatment temperature. The very high saturation magnetization at relatively lower temperature (say 800 C) arises due to the presence of several high magnetic impurities, such as BaFe12O19 and CoFe2O4. The saturation magnetization increases with increasing heat treatment temperature above 900 degrees C, while the coercivity showed a reversed order. (c) 2006 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.matlet.2006.01.077

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Carbon/Fe-Ni-Cu alloy composites were synthesized by carbonization of organometallic polymers obtained from ion exchanged chelate resins. The carbonization was performed at 900 °C in a N gas flow. The composition of the Fe-Ni-Cu alloy in a carbon matrix can be controlled by the adjusting solution compositions in the ion exchange process. The carbon obtained from the organometallic polymer was crystallized to a turbostratic structure. X-ray diffraction patterns revealed that the Cu, Fe and Ni elements in the ion exchanged chelate resins were crystallized to a Fe-Ni-Cu alloy after carbonization at 900°C. This result indicates that the formation of the ternary alloy in the carbon matrix is coincident with the crystallization of the well-ordered turbostratic structure of the carbon matrix. The alloy particles with an average size of about 200-700 nm were widely dispersed in the carbon matrix. The saturation magnetization and coercivity of the composites depended on the alloy composition. The saturation magnetization and coercivity of the carbon/Fe Ni Cu alloy composite were 7.9 emu/g and 167 Oe, respectively. 2 0.52 0.42 0.06

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The formation process of Z-type hexagonal ferrite, Ba Co Fe O , prepared by polymerized complex method and the effects of pH control of citrate complex solution were investigated. By heating a precursor, a pyrolyzed complex polymer, spinel phase, M-type ferrite and Y-type ferrite were formed sequently with increasing the heating temperature. By heating up to 1200°C, monophasic Z-type ferrite was not synthesized in usual preparation procedures. So pH of citrate complex solution was changed and the effects on formation process were examined. As ammonia solution was added to change the complex solution from acidic to basic, the phases in the pyrolysate changed form barium carbonate to barium nitrate and the crystallinity of the constituent phases decreased. By controlling pH to 11, monophasic Z-type ferrite was obtained by heating at 1200°C. On the other hand, pH control of the complex solution toward basic condition suppressed the formation of Y-type ferrite. It was revealed that the optimum conditions for preparing the complex solution depended on phases even for same Ba-Co-Fe-O system. 3 2 24 41

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN INST METALS  

A homogencous layer of molybdenum alumininosilicide Mo(Si,AI)(2) with C(40) structure was made on the sample surface of molybdenum by dip-coating technique using Al-25 rnass%Si liquid at 1123 K. Adherent Al-Si was removed by soaking the dipped samples in the NaOH saturated hydraulic solution. The Mo samples coated with the Mo(Si,AI)2 layer were found to have excellent oxidation resistance in air even at 1473 K due to formulation of a dense alumina film on the sample surface during oxidation. The formation Of Mo-5(Si,AI)(3) layer was also observed 14 at the interface between the Mo substrate and the Mo(Si,AI)(2) layer.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：AMER CERAMIC SOC  

Hematite (alpha-Fe2O3) is one of the most primitive and attractive red pigments. The particle size of hematite seriously influences the reddish tone. The particle with the smallest size of about 100 nm had yellowish red color. With increasing the particle size, the tone color changed systematically from yellowish red to red, dark red, and dark purple. To control the tone color of hematite we prepared Al-substituted Hematite (alpha-(Fe1-xAlx)(2)O-3) by polymerized complex method using iron nitrate (Fe(NO3)(3)-9H(2)O) and aluminum nitrate (Al(NO3)(3)-9H(2)O) as starting materials. The precursors were heat-treated at the temperature between 500 degrees C and 1100 degrees C for 2 hours. When the samples were heat-treated at 1100 degrees C, the solubility limit of Al in hematite up to 13%. The particle size of the sample heat-treated at 1000 degrees C without Al substitution was about 2 pm, while the one with 10% Al-substitution was about 200 nm. The Al substitution suppressed the grain growth of hematite. With increasing the Al content, the temperature at which the color of hematite changed from yellowish red to dark purple increased monotonically. Moreover the Al-substitution seemed to stabilize the maghemite phase (gamma-Fe2O3) at higher temperature.. The XRD pattern of Al-substituted samples heat-treated at 700 degrees C showed some diffraction lines assigned to gamma-Fe2O3. This would be a reason to suppress the grain growth of hematite.

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Magnetic properties of La-Co substituted M-type Sr ferrite powders were studied. Samples were prepared from the citrate precursors. High purity reagent of Sr(NO3)(2), Fe(NO3)(3)(.)9H(2)O, Co(NO3)(2)(6H2O)-H-. and La2O3 were used as starting materials. They were dissolved in distilled water with citric acid. The nominal molar ratio of the mixed solutions were I : 5 of metal : citric acid. Prepared aqueous solution was heated at 120 degrees C for dehydration and gelling. Thermal pyrolysis was carried out by heating the gel at the temperature range between 300 degrees C and 350 degrees C for 1h in air. The obtained precursor powders were ground with an alumina mortar and compacted by uniaxial pressing into disk specimens, 20 mm in diameter and I mm thick, and then heated at temperature range between 750 degrees C and 900 degrees C in air. Phase identification and determination of lattice parameters were carried out by powder X-ray diffraction (XRD). Scanning Electron Microscope (SEM) was utilized to investigate the microstructure of the polycrystalline ferrites. Magnetic properties were discussed by magnetization measurements by using a vibration sample magnetometer (VSM) at a maximum applied field of 16 kOe. Magnetization and coercive force were measured at room temperature. Temperature dependence of residual magnetization was measured for determine the Curie temperature. The La-Co substituted SrM ferrite powders prepared in this study showed typical magnetic hysterisis of hard ferrite. Extreme enhancement of coercive force was performed by La-Co substitution. Maximum value of coercive force achieved in this study is 8.0 kOe. This enhancement of coercive force is realized by mainly increase of magnetocrystal line anisotropy caused by La-Co substitution.

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Thin films of the hematite-ilmenite solid solution (ot-Fe2O3-FeTiO3) are one of the candidates for practical magnetic semiconductors with a high Curie temperature (Tc). We have successfully prepared well-crystallized epitaxial Fe1.2Ti0.8O3 films on alpha-Al2O3 substrates by using a reactive helicon plasma sputtering technique. Only the films having the R3 symmetry had large ferrimagnetic moments, where the Fe-rich and the Ti-rich cation layers were alternately stacked along the c-axis. To obtain the order structure (R3) for the Fe1.2Ti0.8O3 films, a higher substrate temperature and/or post annealing at 600 degrees C were very effective. Unfortunately the Fe1.2Ti0.8O3 solution has the lower Tc of about 250 K in bulk form. Trying to raise up the Tc of Fe1.2Ti0.8O3 multilayered films of alpha-Fe2O3/Fe1.2Ti0.8O3 were also prepared. At the moment, though, we did not success the preparation of high-Tc multilayered films beyond the room temperature. Low temperature magnetization measurements and Mossbauer spectroscopy suggested that the exchange coupling between alpha-Fe2O3 and Fe1.2Ti0.8O3 seemed to provide a large possibility to increase the Tc of Fe1.2Ti0.8O3 layers beyond the room temperature.

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Well-crystallized Y-type hexagonal ferrite films with highly c-axis orientation were successfully preparated on Ag substrates by polymerized complex method. The Co-2-Y phase started to form at 780 degrees C and nearly single-phase Of Co-2-Y was formed when the films heat-treated above 820 degrees C. The films had large in-plane magnetic anisotropy with small in-plane Hc of about 300 Oe. When it was heat-treated at 860 degrees C, the Ms had maximam value of 192 emu/cm(3). The heat-treatment time also influence the magnetic properties of the films. The films with nearly the single-phase Of Co-2-Y were formed when the films had stoichiometric Ba:Co:Fe ratio of 1:1:6.

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Synthesis and magnetic properties of M-type hexagonal ferrites with chemical composition of AFe12O19 (A = Ba and Sr) were studied. Nitrates of barium, strontium and iron were used as starting materials. The precursor of M-type ferrites was prepared mainly by the polymerization of metal-citric complex with various amounts of ethylene glycol, and heating the gel at 300 oC. The precursor was ground, pressed by uniaxial compression in a die and heated at 750-950 oC in air. From these results, large coercive force of the samples in this study is probably caused by achievement of small grain size under the single domain size by polymerized complex method.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：MATERIALS RESEARCH SOCIETY  

Epitaxial thin films of (001)-oriented FeTiO3+delta were prepared on alpha-Al2O3(001) single crystalline substrates by helicon plasma sputtering technique. The FeTiO3+ films had large oxygen nonstoichiometty, which seriously depended on both substrate temperature and oxygen pressure during the sputtering deposition. The valence states of Fe ions in FeTiO3+delta changed monotonically from Fe2+ to Fe3+ with decreasing the substrate temperature from 900 to 400degreesC or with increasing the oxygen pressure from 0.9 to 1.8x10(-6) Pa. ne change of Fe valence states from Fe2+ to Fe3+ induced the magnetic phase transition only for the films prepared at 900degreesC. The films containing Fe2+ were paramagnetic while those with Fe3+ were antiferromagnetic at room temperature. The oxygen nonstoichiometry of the FeTiO3+delta films was probably produced by cation vacancies and disarrangement of Fe3+ and Ti4+ ions, which randomly occupied both interstitial and substitutional sites of the FeTiO3 related structure.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：MATERIALS RESEARCH SOCIETY  

Since the beginning of the 18th century A.D., an artificial iron oxide pigment (hematite, called "bengara" in Japanese) and having a beautiful yellowish red color, has been produced in Japan and applied to pottery, textiles and paintings. However, in 1965 the traditional "bengara" could not be produced anymore, mainly because of environmental pollution. The purpose of this study is to make clear the features of traditional "bengara" and to reproduce high quality "bengara" using modem high-purity reagents. Traditional "bengara" has been characterized as hematite containing a small amount of Al. The average size of the "bengara" particles is approximately 100 nm. The color becomes more, yellowish-red with increasing Al content. A monophase of hematite prepared by beating a mixture FeSO4-7H(2)O and alpha-Al2O3 to about 680 degreesC included a small amount of Al substituted in a solid solution. The particle size greatly decreased as the heat treatment temperature was decreased : 100 nm at 770 degreesC but 50 nm at 650 degreesC. The color of the particles becomes more vivid as the temperature is decreased, but within bounds this color is independent of the amount of Al in solid solution.

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Well-crystallized Y-type hexagonal ferrite (Me -Y, Me=Zn and Co) films with highly c-axis orientation were successfully prepared on Ag substrates by dip coating technique. The procedure consisted of preparation of homogeneous metal-organic solution by polymerized complex method, dip coating and subsequent heat-treatment. The films deposited on α-Al O easily reacted with the substrate, while the films deposited on Ag formed hexagonal planar structures. The formation temperature of Me -Y structures on Ag was 800 °C, which was much lower than that of Me -Y bulk crystals. The Me -Y films on Ag had a large in-plane magnetic anisotropy. The observed anisotropy field of the Zn -Y film was about 13 kOe and that of Co -Y was too large beyond our experimental limits. © 2001 Materials Research Society. 2 2 3 2 2 2 2 2

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In order to develop wide-band microwave absorbers we tried to prepare composite absorbers between the magnetic loss (Ni-Zn-ferrite) and the dielectric loss (SiC) materials. The dry or wet mixtures of Ni-Zn-ferrite and polycarbosilane (PCS) were cured in air and were then subjected to pyrolysis forming of the ferrite composites. The composites produced by the wet mixing had granular structure: the PCS surrounding the ferrite particles suppressed the sintering and the grain growth of the ferrite composites during pyrolysis. The matching frequency due to the magnetic loss linearly increased with increasing the PCS content. Moreover the ferrite/SiC hemi-crystallized composite cured at 473 K for 24 hours showed wide-band absorption spectrum having the both magnetic and dielectric losses. © 2001 Materials Research Society.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

The magnetization of V5S8 and V5Se8 was measured in pulsed high magnetic fields up to 39 T. The anomalies were observed in the magnetization curves for both V5S8 and V5Se8. For V5S8, the anomaly at lower field is thought to correspond to spin flopping, The magnetization curves exhibited saturation for both compounds and the values of the ordered moments for V5S8 and V5Se8 were estimated to be 1.5 and 1.2 mu (B)/V-1 from the saturation moments. respectively. Our results support the magnetic structure of V5S8 proposed by neutron diffraction measurements. (C) 2000 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0304-8853(00)00509-6

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：MATERIALS RESEARCH SOCIETY  

Solid solution films of the alpha -Fe2O3-FeTiO3 series are one of the candidates for noble half-metallic oxides. They were epitaxially formed on alpha -Al2O3(001) single crystalline substrates by O-2-reactive evaporation method. The Fe2-XTiXO3+delta films prepared at higher Ts=973 K and with larger Ti content x greater than or equal to0.4 had the ilmenite structure with R3 ($) over bar symmetry. Other films at lower Ts or with smaller x possessed the corundum structure with R3 $($) over bar $c. Only the films with R3 ($) over bar symmetry had large ferrimagnetic moments, though the observed spontaneous magnetization was less than half of the ideal value expected from the fully ordered structure. Room temperature resistivity of intermediate composites dropped to 10(-1)Omega cm due to the formation of the mixed valence states between Fe2+ and Fe3+. However the Fe2+ content of the films was rather small as compared with stoichiometric Fe2-xTixO3. The Ti-rich films had large oxygen nonstoichiometry of about delta =0.3.

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：一般社団法人 粉体粉末冶金協会  

Bi-2223 bulk superconductors were irradiated with 290MeV/n40Ar18+ions.40Ar18+irradiation effects on flux pinning of Bi-2223, which were estimated as ΔM from magnetic hysteresis loops measured by SQUID and VSM, were discussed. Irradiated samples had enlarged magnetic hysteresis loops than unirradiated samples. Moreover, the increment of ΔM depended on depth from the irradiation surface. Microstructure of irradiated samples were observed by high-resolution transmission electron microscopy (HR-TEM). However, irradiation defects such as the columnar defects were not observed in these samples.

DOI： 10.2497/jjspm.46.994

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：一般社団法人 粉体粉末冶金協会  

The effects of lithium doping by solid state reaction on the electrochemical intercalation into the Bi-2212 phase with lithium were investigated through the structure and superconducting properties. The expansion rates of lattice parameters with respect to the amount of lithium intercalated by electrochemical reaction decreased with increasing the amount of lithium doped by solid state reaction. The change of superconducting critical temperature with respect to average valence of copper became small with increasing the amount of lithium doped by solid state reaction. The electrochemical reaction removed lithium from Bi-2212 phase as much as the amount of lithium intercalated by electrochemical reaction. The result supports the possibility that lithium doped by solid state reaction and electrochemical reaction occupies the different sites in the Bi-2212 phase.

DOI： 10.2497/jjspm.46.990

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Funtai Funmatsu Yakin Kyokai  

FeTiO3-α-Fe2O3 solid solution films were epitaxially formed on an α-Al2O3 (001) single crystalline substrate by activated reactive evaporation method. The films prepared at low substrate temperature of 500°C had the corundum structure where Fe and Ti ions occupied the cation sites randomly. While the Fe2-xTixO3 films with x ≥ 0.4 prepared at 700°C had the ilmenite structure where Fe and Ti ions were arranged in order. Only the films with the ordered Fe and Ti ions had large ferrimagnetic moments, though the observed spontaneous magnetization was less than a half of the ideal value expected from the fully ordered ions. Moreover the resistivity of the solid solution films dropped to 10-1Ωcm due to the formation of the mixed valence states between Fe2+ and Fe3+. We revealed this system was one of the candidates for new oxide magnetic semiconductor films.

DOI： 10.2497/jjspm.46.643

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Y2Ba4Cu7O15-delta compounds were characterized by microscopic investigation using TEM and NQR techniques. We synthesized Y247 compounds by two kinds of preparation methods: the conventional solid-state reaction (sample A) and the polymerized-complex method (sample B), The value of T-c for sample A was found to be 65 It and that for sample B was 93 It by ac-chi measurements. As a result of TEM experiments, stacking faults along the c axis were observed more frequently in sample B than in sample a. These stacking faults resulted in microdomains containing pure Y123 or Y124 thin blocks of several unit cells. NQR experiments revealed that the microscopic environment of Co(2) sites in sample A differed from either of those in the Y123 and Y124 compounds, NQR frequency values (nu(Q)) of Cu(2) sites agreed well with those calculated by the point charge model applied for the Y247 structure, The spectra of Cu(2) sites in sample B could be regarded, however, as a combination of those of pure Y123, Y124, and also Y247 compounds. This fact was coincident with the result off TEM experiments. We concluded that the superconductivity of Y247 with higher T-c originates from the thin block of Y123. (C) 1998 Academic Press.

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Funtai Funamtsu Yakin Kyokai/Japan Soc. of Powder Metallurgy  

The structural, electric and magnetic properties of (100)-oriented Fe3O4/NiO and Fe3O4/CoO superlattices on MgO(100) have been studied. The films were prepared by an activated reactive evaporation method. The lattice constants of each layers were a little changed from the bulk values due to a lattice mismatch with the substrate. The Fe 2p XPS of both Fe3O4/NiO and Fe3O4/CoO interfaces suggested the formation of stoichiometric Fe3O4. The saturation magnetizations (Ms) of Fe3O4/MO superlattices were compared with that of a Fe3O4 thin film as a function of the thickness of MO layers. The reduction in Ms of Fe3O4/NiO could be linked with the large exchange coupling with NiO. While the increase in Ms of Fe3O4/CoO was probably caused by the ferromagnetic coupling of the CoO interface with the Fe3O4 layer.

DOI： 10.2497/jjspm.45.58

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Language：Japanese   Publisher：Japan Society of Powder and Powder Metallurgy  

Effects of Li-addition on the formation process of Bi-2212 phase have been studied for samples with a nominal composition of Bi:Sr:Ca:Cu:Li=2:1.5:1.5:2:0.2. Samples were heated at temperatures ranging between 560°C and 730°C in air with various heating rates. The formation range of the phases formed was determined by powder X-ray diffraction method(XRD). Li-addition seems to bring two different effects on the formation process of the Bi-2212 phase: an acceleration of the formation of Bi-2201 phase on heating and early stage of holding at 730°C, and a promotion of phase transformation of Bi-2201 phase to Bi-2212 phase after holding for a few hours. Such two effects can be explained by formation of two different oxides which were newly found. The microstructures of the newly found oxides were observed by scanning electron microscopy(SEM), high-resolution transmission electron microscopy(HR-TEM) and electron diffraction(ED).

DOI： 10.2497/jjspm.45.129

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Language：English   Publisher：The Magnetics Society of Japan  

&nbsp;&nbsp;We provided formation conditions of (001)-oriented epitaxial Fe_2-XTi_XO₃ (X=0.0&sim;1.0) films by activated reactive evaporation technique. Structural and magnetic properties of the films depended on both the composition and the substrate temperature. The lower substrate temperature below 600&deg;C brought about disordered Ti and Fe ions within the hexagonal oxygen lattices having the same symmetry as hematite (R3c). While the films with X≧0.75 prepared at higher temperature of 700&deg;C were formed into the ordered structure as ilmenite (R3). The ordered films with 0.75≦X<1.0 were strong ferrimagnetic though the spontaneous moments were fairly small than the ideal values.

DOI： 10.3379/jmsjmag.22.S1_206

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Effects of lithium intercalation into the Bi-2212 phase on its structural and superconducting properties were studied using monophasic samples of Bi Sr Ca Cu O lithiated through an electrochemical method at a constant applied voltage at room temperature. The amount of doped lithium was found by ICP analysis to be in the range of 0 ≤ y ≤ 0.37 for Li Bi Sr Ca Cu O depending upon experimental conditions. However, the oxygen content determined by coulometric titration remained almost unchanged after the lithiation. The electrochemical lithium intercalation led to a very interesting change in T , though the original tetragonal structure and oxygen content remained essentially the same: T first increased rapidly as y increased, reached a maximum of 94 K, and then decreased to zero. The drastic T change is ascribed to a decrease in the hole concentration. Thus, the electrochemical lithium-doping provides us with a great advantage of easily controlling T at room temperature by changing electrochemical conditions while keeping the original crystal symmetry. © 1997 Elsevier Science B.V. 2 1.5 1.5 2 z y 2 1.5 1.5 2 z c c c c

DOI： 10.1016/S0921-4534(97)00177-9

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Funtai Funamtsu Yakin Kyokai/Japan Soc. of Powder Metallurgy  

The effects of electrochemical Li-doping on superconducting properties of the Bi-2212 phase have been investigated. The electrochemical Li-doping into the 2212 phase was first succeed with remaining the original crystal structure and without formation of any second phase. Maximum Li content y as LiyBi2Sr1.5Ca1.5Cu2O z by this electrochemical reaction was found to be 0.37. The Li content increased with increasing in reaction time and applied potential. The lattice parameters (a, c) of the Bi-2212 crystals increased continuously from (5.397Å, 30.69Å) for y=0.0 to (5.411Å, 30.89Å) for y=0.37. Tc of the doped samples continuously decreased to 0K for around y=0.27.

DOI： 10.2497/jjspm.44.142

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA LAUSANNE  

The cubic YbCu5 compound with the AuBe5-type structure was prepared for the first time under a pressure of 1.5 GPa and annealed at 650 degrees C. The previously reported hexagonal YbCu5 phase with the CaCu5-type structure was also confirmed to be stable under relatively lower pressure and at higher temperature. In contrast to the divalent non-magnetic state of Yb ion in the hexagonal phase, Yb ion in the cubic phase was found to be in the trivalent magnetic state. The cubic YbCu5 phase probably presents a reasonable conjunction for a family of isostructural YbCu(5-x)M(x) (M = In, Ag, etc.) compounds, both in crystallographic aspect and in physical properties.

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The interlayer coupling of superconducting NbN thin films through metallic Ag and insulating CNx thin films have been investigated from resistivity measurements of [NbN(170 Angstrom)/X(t Angstrom)](10) (X = Ag, CNx) multilayered films. When Ag layer thicknesses are thicker than 150 Angstrom, NbN layers are decoupled and the transition temperatures are nearly equal to 8.2 K. The transition temperature increases with decreasing Ag layer thickness, obeying Werthamer's theory for the proximity effect. On the other hand, with the increase of CNx layer thickness, the transition temperature is lowered steeply and almost linearly, indicating a coupling mechanism other than the proximity effect.

DOI： 10.1016/0921-4534(95)00500-5

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Language：English   Publisher：PHYSICAL SOC JAPAN  

Compositional phase separation was observed in La2-xBaxCuOy near the optimum composition (x is similar to 0.16) for superconductivity with a decisive miscibility gap by means of X-ray diffraction measurements. The phase-separated samples do not show intrinsic superconductivity. Therefore, the superconductive compound in this system is not in a chemical equilibrium state at low temperatures, but is a high-temperature phase obtained by quenching to room temperature. The critical temperature of the phase separation T(p) takes a maximum value of 950-degrees-C at x is similar to 0.16, suggesting that phase instability is crucial for high-T(c), superconductors. The end composition of the miscibility gap in the Ba-poor composition region was found to be 0.12, which is a singular point from crystallographic and band structural standpoints.

DOI： 10.1143/JPSJ.62.1114

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Ilmenite-hematite solid solution (Fe2-xTixO3) is one of the candidates for high-temperature magnetic semiconductors. Well-crystallized and epitaxially formed Fe2-xTixO3 films on alpha-Al2O3 (11 (2) over bar0) single-crystalline substrates were tried to fabricate by using reactive sputtering technique. The detailed structural properties of (11 (2) over bar0)-oriented epitaxial Fe1.4Ti0.6O3 films were analyzed by using transmission electron microscope (TEM). The films showed large magnetization and typical semiconductive conduction at room temperature. However their anisotropic properties were rather small than expected, though the films had good crystallinity with preferred orientation. The TEM observations clearly revealed that the (11 (2) over bar 0)-oriented Fe1.4Ti0.6O3 films on alpha-Al2O3(11 (2) over bar0) were partly composed of the (0001)-oriented grains. Formation of the (0001)-oriented grains could reduce the anisotropic properties of the (11 (2) over bar0)-oriented films. (C) 2015 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.tsf.2015.04.028

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DOI： 10.2497/jjspm.61.S90

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DOI： 10.2497/jjspm.61.S327

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DOI： 10.4164/sptj.51.629

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DOI： 10.20665/kakyoshi.60.11_484

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Language：Japanese   Publisher：The Physical Society of Japan (JPS)  

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We report the synthesis and magnetic properties of the AgI-intercalated misfit-layer cobalt oxide Bi Ca Co O . The AgI-intercalated Bi Ca Co O was prepared by the guest exchange reaction from the I -intercalated one. SEM-EDX analysis exhibited the stoichiometric ratio of Ag/I and the guest concentration as (AgI)Bi Ca Co O on the basis of Co = 2. After the AgI intercalation, the lattice parameter along the c-axis calculated from X-ray diffraction patterns was 21.68 Å, which was drastically increased not only from the non intercalated host phase (14.68 Å) but also from the I -intercalated phase (18.08 Å). After the AgI intercalation, magnetic susceptibility measurements revealed that the antiferromagnetic Weiss temperature and the effective magnetic moment in Co ion simultaneously decreased compared with the non-intercalated host compound. © 2008 Elsevier B.V. All rights reserved. 1.8 2 2 z 1.8 2 2 z 2 1.8 2 2 z 2

DOI： 10.1016/j.matlet.2008.10.032

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DOI： 10.1016/j.jmmm.2008.01.046

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Characterization of biogenic iron oxide sheaths produced by Leptothrix ochracea (L. ochracea) was investigated. The sheaths had average inner- and outer-diameters of 1.08 ± 0.15 and 1.35 ± 0.14 μm, respectively. Their length ranged from 10-2000 μm. Outer and inner surface of each sheath were composed of fibrous and spherical particles, respectively. The width of fibrous particles was approx. 20 nm, while the diameter of spherical particles was 20-120 nm. The chemical composition of the sheaths was Fe: Si: P = 73: 22: 5 with the exception of H and O. The sheaths had similar structure to that of 2-line ferrihydrite.

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Language：English   Publisher：Faculty of Engineering, Okayama University  

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Some features of characteristic iron oxide sheaths which the iron oxidizing bacteria Leptothrix ochracea (L. oceracea) formed were studied in order to make clear their morphology microstructure, chemical composition, and crystal structure through scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDX), and X-ray diffraction (XRD). Each sheath was a hollow tube with average outer and inner diameters of 1.1 and 1.4 μm, respectively. Their length ranged from 10 to 200 μm and the aspect ratio was 10-200. Each sheath was constructed by very small particles with a diameter of less than 100 nm. The hollow sheaths were mainly composed of Fe and O with small amounts of Si and P. The chemical composition analyzed by EDX was roughly Fe:Si:P=80:15:5 with the exception of O. XRD measurement revealed that crystal structures of the sheath were similar to that of 2-line ferrihydrite. The sheath showed spin-glass-like magnetic properties. © 2006 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jmmm.2006.10.793

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Cerium doped hematite powders obtained by polymeric complex method following the hydrolysis of FeCl · 6H O and Ce(NH ) (NO )6. X-ray diffraction pattern of cerium doped samples obtained at 1000°C̃ 1200°C for two hours in air revealed some solubility of cerium ion in α-Fe O over the composition range of 5%̃15 at% that were characterized by the shifting of X-ray diffraction peaks compared with the internal silicon standard. X-ray Photoelectron Spectra investigations revealed the existence of Ce ion at higher temperature. Unit cell parameters were found to expand due to the incorporation of cerium ions into the hematite lattice. Field Emission Scanning Electron Microscopy studies showed that the growth of particles was suppressed in the appearance of cerium ions into the α-Fe O lattice. Fe Ce O exhibits much lower magnetization due to the incorporation of non-magnetic cerium ions into the α-Fe O . Spectroscopy measurement evidenced that cerium doped hematite samples exhibited brighter yellowish red color tone than that of pure α-Fe O . 3 2 4 2 3 2 3 3+ 2 3 2-x x 3 2 3 2 3

DOI： 10.2497/jjspm.54.112

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Ilmenite-hematite solid solution (Fe Ti O ) is one of the candidates for practical magnetic semiconductors with the high Curie temperature (T ). We have successfully prepared well-crystallized and epitaxial Fe Ti O films by using a reactive helicon plasma sputtering technique. The structural characterizations indicated that the films had the order structure (R over(3, -) symmetry), where Ti- and Fe-rich layers were stacked alternately along the c-axis, without any secondary phase. The subsequent annealing of the films in vacuum at 700 °C promoted the R over(3, -) symmetry. Only the films having the good R over(3, -) symmetry had large ferrimagnetic moments at room temperature. The resistivities of the films clearly showed semiconducting behavior, i.e., logarithmic resistivity showed a monotonous increase with increasing the inverse temperature. The minimum room temperature resistivity of the films was about 10 Ω cm. From the Hall effect measurement all films had n-type conduction. The carrier concentration was estimated to be about 10 -10 cm , depending on the annealing conditions. © 2006 Elsevier B.V. All rights reserved. 2-x x 3 C 1.4 0.6 3 -1 19 21 -3

DOI： 10.1016/j.jmmm.2006.10.783

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The polymeric complex method has been employed to investigate the effects of substitution by lanthanum into hematite powder on structures, morphology and color tone properties. X-ray diffraction measurements evidenced the existence of Fe La O at 1000 °C-1200 °C by shifting peaks to lower angles. At higher temperature, lattice parameters and cell volume were found to expand due to the incorporation of La ion into the hematite in the range 301.98-303.87 Å . Crystalline size decreased when increasing the amount of La ion in the reaction process. Suppression of particle growth was observed by the Field Emission Scanning Electron Microscopy studies at higher temperatures. Brighter yellowish-red color than that of pure hematite was obtained and it grew into deeper color tone rapidly by increasing the amount of La ion into the hematite. © 2007. 2 - x x 3 3+ 3 3+ 3+

DOI： 10.1016/j.matlet.2006.12.032

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Iodine intercalation and deintercalation of a Sr-free Bi-based cuprate, Bi (La,Na) CuO:, have been investigated. It has been confirmed by powder X-ray diffraction and thermogravimetric analysis that the stage-1 iodine-intercalated compound Bi (La,Na) CuO l with x=1.0 was formed. As in the case of a Bi (Sr,La) CuO: (Bi-2201) specimen, expansion of the c-length of the stage-1 iodine-intercalated compound was 3.6 Å, compared with one half that of host compound. After deintercalation of the intercalated iodine, the stage-1 iodine-intercalated compound returned reversibly to the host compound. The powder X-ray diffraction pattern showed the formation of the intermediate phase containing a certain amount of iodine, not assigned to the stage-2 intercalated compound, during the deintercalation. Neither host compound nor iodine-intercalated compound exhibited superconductivity down to 2 K. 2 2 2 2 7 x 2 2

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In this study, low temperature preparation conditions for Co Z (3BaO·2CoO·12Fe O ) particles were investigated by using alkaline halide method. The obtained particles were characterized by using X-ray diffraction and scanning electron microscopy techniques. Many factors such as the metal compositions, heating temperature, heating and cooling rates, and amount of flux reagents were changed for the preparation. The X-ray diffraction analysis indicated that (1) the metal compositions, (2) flux reagent, and (3) heating rate were important to obtain Co Z at low temperature using the alkaline halide method. Nearly monophasic Co Z was formed under the following conditions: metal compositional ratio of Ba : Co: Fe = 3.0 : 1.5 : 24 with 10wt% BaCl flux and rapid heating to 1200 °C for 6 hours. Co Z powders mixed with an EPDM rubber were pressed to a sheet form. The electromagnetic properties of rubber sheets were examined to apply to use as an electromagnetic wave absorber. 2 2 3 2 2 2 2

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We have successfully prepared Carbon/Fe-Co alloy composites starting from metal organic precursors synthesized by polymerized complex method. The carbon/Fe-Co alloy composites were obtained after the carbonization of the precursors heat-treated at ambient pressure and lower temperatures ranging from 500 to 700°C in N 2 gas flow. Crystalline sizes of both carbon matrix and Fe-Co alloy particles were determined by X-ray diffraction measurements as a function of the Co concentration and the carbonized temperature. The alloy particles were widely dispersed in the carbon matrix and the particle size carbonized at 600°C was about 20-50nm observed by scanning electron microscopy. The composite carbonized at 600°C had very small coercivity of 14 Oe and exhibited relatively large permeability spectra at frequency of GHz range.

DOI： 10.2497/jjspm.52.640

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We have successfully prepared Carbon/Fe-Co alloy composites starting from metal organic precursors synthesized by polymerized complex method. The carbon/Fe-Co alloy composites were obtained after the carbonization of the precursors heat-treated at ambient pressure and lower temperatures ranging from 500 to 700°C in N 2 gas flow. Crystalline sizes of both carbon matrix and Fe-Co alloy particles were determined by X-ray diffraction measurements as a function of the Co concentration and the carbonized temperature. The alloy particles were widely dispersed in the carbon matrix and the particle size carbonized at 600°C was about 20-50nm observed by scanning electron microscopy. The composite carbonized at 600°C had very small coercivity of 14 Oe and exhibited relatively large permeability spectra at frequency of GHz range.

DOI： 10.2497/jjspm.52.640

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A stable precursor for CoFe O thin film was prepared by sol-gel technique from the aqueous solution of FeCl •6H O and CoCl •6H O. Sol was deposited on a naturally oxidized silicon-substrate by spinning technique (2000 rpm) and heat treated at different temperatures ranging from 700 to 1100°C. Thickness of the films was controlled in the range of 400-500 nm and all the films were characterized by using XRD and SEM. The effects of temperature and the composition on the formation of CoFe O thin film were also studied. Films obtained at relatively lower temperature showed multi-phases of α-Fe O , CoFe O and CoO while the formation of CoFe O phase increases with increasing temperature. Furthermore, the composition of the solution in mol% has great role on the formation of CoFe O films and the film containing 50 mol% of Co exhibited CoFe O mono-phase. Surface morphology of the films was studied by scanning electron microscope (SEM). Magnetic properties of the films, studied by using vibrating sample magnetometer (VSM), showed relatively high saturation magnetization (8.04-22.21 kWb/m ) as well as high coercivity (44.59-63.30 kA/m). Saturation magnetization also increases with increasing heat treatment temperature. © 2005 Springer Science + Business Media, Inc. 2 4 3 2 2 2 2 4 2 3 2 4 2 4 2 4 2 4 2+ 2

DOI： 10.1007/s10853-005-3819-1

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The traditional Japanese red pigment called "bengara" has vivid yellowish red coloras compared with the pure hematite powder. The traditional "bengara" is composed of mainly hematite, for impurities, a small amount of quartz and corundum. The color of reproduced "bengara" was great influenced by the particles shape and size of hematite powder.

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DOI： 10.1109/TMAG.2005.854820

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Fine particles of cerium substituted hematite with different compositions were prepared by the sol-gel method from the aqueous solution of their corresponding metal salts. Mixed hydroxides of Fe and Ce were obtained by reacting aqueous NH with the aqueous solution of FeCl and Ce(NH ) (NO ) at pH 2.5-3.0) and they were heat treated at different temperatures between 400 and 1200°C in air for 2 h to get the mixed oxide product. Thermal analysis and X-ray diffraction studies revealed the coexistence of Fe O and CeO phase separately up to 900°C, and covalent interaction between them above 1000°C, which was evidenced by the shifting of the XRD peaks. Unit cell parameters and the cell volumes (V) of the samples derived between 1000 and 1200°C were found to be in the range a = 5.045-5.048 ± 0.007 Å, c = 13.774-13.815 ± 0.041 Å and V = 303.608-304.874 Å respectively. It was observed that both the lattice parameters and the cell volumes were higher than that of the pure α-Fe O (a = 5.036 Å, c = 13.749 Å, V = 301.976 Å ) system. The expansion of lattice parameters further supported the incorporation of the large Ce ion into the α-Fe O matrix. The lattice parameter increased with increasing Ce ion loading. FESEM studies showed the growth of the particles with increasing temperature though it was suppressed due to the presence of Ce ions as compared to the pure system. © 2005 Elsevier B.V. All rights reserved. 3+ 4+ 3 3 4+ 4+ 4+ 3 3 3 2 3 6 2 3 2 2 3 2 3

DOI： 10.1016/j.matlet.2005.06.056

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Spinel-type Co Fe O (x=0-0.5) thin films (∼450 nm thickness) on SiO glass substrate were prepared by the sol-gel method using spinning technique (2000 rpm) from the aqueous solution of FeCl .6H O and CoCl .6H O. All the films were heat treated at different temperatures ranging from 700 to 1100°C. The films were structurally characterized by using the X-ray diffraction technique (XRD), and the morphology was studied by field emission scanning electron microscope (FESEM). The effects of temperature and the composition ([Co ]/ [Fe ] ratio) on the formation of Co Fe O thin films were also studied. The films obtained at relatively low temperature showed mixed phases of α-Fe O , CoO, along with CoFe O , while the formation of the CoFe O phase increases with increasing temperature. Furthermore, the composition of the solution in terms of [Co ]/[Fe ] plays a great role on the formation and magnetic properties of the films. The magnetic properties of the films, studied using vibrating sample magnetometer (VSM), showed relatively small saturation magnetization, and coercivity was observed to be low as compared with that of other reports. Saturation magnetization also increases with increasing heat treatment temperature. © 2004 Elsevier B.V. All rights reserved. 1+x 2-x 4 2 3 2 2 2 1+x 2-x 4 2 3 2 4 2 4 2+ 3+ 2+ 3+

DOI： 10.1016/j.matlet.2004.09.023

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Nanograined hexagonal barium ferrite (BaFe O ) thin films have been developed on naturally oxidized Si substrates by sol-gel technique using aqueous solution of metal chlorides. Coated films were heat treated at different temperatures ranging from 450 to 900°C, and all the films were characterized by using X-ray diffraction (XRD), inductive coupled plasma (ICP) spectroscopy, and field emission scanning electron microscopy (FESEM). The effects of temperature on the formation of BaFe O thin film were studied, and it was observed that hexagonal barium ferrite thin films with grain sizes of about 50 nm were formed above 700°C. Study on the magnetic properties of the films by vibrating sample magnetometer (VSM) showed that films exhibited large saturation magnetization and high coercivity in the range 247-355 emu/cm and 2.70-4.22 kOe, respectively, while the Curie temperatures (□ ) were in the range 443-457°C. The effects of temperatures on the magnetic properties were also studied. © 2004 Elsevier B.V. All rights reserved. 12 19 12 19 c 3

DOI： 10.1016/j.matlet.2004.10.026

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Unique magnetic and electric properties of solid solutions of ilmenite (FeTiO ) and hematite (α-Fe O ) can be expected for new electronics, optics and spintronics applications. We have successfully prepared well-crystallized and epitaxial Fe Ti O (001) films on α-Al O (001) substrates by reactive helicon plasma-sputtering technique. Structure, magnetic and electric properties of the films were seriously dependent on both the oxygen pressure and the substrate temperature during the sputtering deposition. The subsequent annealing of the films in vacuum at high temperature (600 °C) promoted the order (R3̄) structure of Fe Ti O , where the Ti and Fe ions occupied the cation sites alternatively along the c-axis. Only the films having the R3̄ symmetry had large ferrimagnetic moments at low temperature (78 K), although the magnetization values were depending on not only the order parameter between the R3̄ and the R3̄c structures but also the oxidization states of Fe ions in Fe Ti O . The film prepared at an oxygen partial pressure ratio of 1.4% and substrate temperature of 400 °C had considerably large spontaneous magnetization of 275 emu/cm at 78 K after the subsequent annealing at 600 °C. However, highly oxidized nonstoichiometirc Fe Ti O films with the R3̄c symmetry could not give the ordered structure with the R3̄ symmetry. © 2004 Elsevier B.V. All rights reserved. 3 2 3 1.23 0.77 3+δ 2 3 1.23 0.77 3+δ 1.23 0.77 3+δ 1.23 0.77 3+δ 3

DOI： 10.1016/j.ssi.2004.02.051

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The effect of Co ion on the magnetic properties of the sol-gel derived cobalt ferrite thin films (400 nm thickness) was studied. Films with different solution composition ([Co ]/[Fe ] = 0.5-1.0) were deposited on a Si substrate from the precursor containing an aqueous solution of FeCl ·6H O and CoCl · 6H O. Deposited films were heat treated at different temperatures (700-1100 °C) and were characterized by X-ray diffraction using Cu Kα radiation. The films containing a nonstoichiometric α-(Fe Co ) O phase were obtained in addition to a small amount of CoO at relatively lower temperatures. With increasing heat treatment temperature, nonstoichiometric α-(Fe Co ) O was decomposed to stoichiometric α-Fe O and the CoFe O phase was intensified. Only the films obtained from the solution enriched with Co showed the single phase of CoFe O , though the Co to Fe content ratio analyzed by inductive coupled plasma spectroscopy (ICP) and energy dispersive X-ray spectroscopy (EDX) was nearly consistent with that of the starting solutions. The study of surface morphology of the films by using field emission scanning electron microscope (FESEM) showed that films were homogeneously distributed throughout the surface of the substrate and the grain sizes were in the range of 60 to 140 nm. Magnetic properties of the films, including the Curie temperature, were studied by using a vibrating sample magnetometer (VSM) and conversion electron Mössbauer spectroscopy (CEMS). The Curie temperature and the magnetic hyperfine fields of the films slightly decreased with increasing molar ratio of the Co and Fe ions while the saturation magnetization reached a maximum value with the film composition of x = 0.28. 2+ 2+ 3+ 2+ 3+ 3 2 2 2 1-x x 2 3 1-x x 2 3 2 3 2 4 2 4

DOI： 10.1039/b410163d

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Well-crystallized Y-type hexagonal ferrite films with highly c-axis orientation were successfully prepared on Ag, Au and Pt substrates by polymerized complex method. The films prepared on Ag had considerably low formation temperature of 800°C, while those on An and Pt were formed at above 1000°C. The films had large in-plane magnetic anisotropy, with small coercivity. Hexagonal grains structures were developed on the substrates. © 2003 Published by Elsevier B.V.

DOI： 10.1016/j.jmmm.2003.12.885

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Epitaxial FeTiO (001) films were prepared on α-Al O (001) substrates by helicon plasma sputtering technique. Structure and magnetic properties of FeTiO film were largely dependent on the residual oxygen pressure (Po ) during the sputtering deposition. The films prepared at lower Po had an ilmenite (R3̄) structure, while a corundum (R3̄c) structure was observed in the case of higher Po . The oxidation state of Fe in FeTiO films changed monotonically from Fe to Fe with increasing the Po . The films with the R3̄ symmetry were ferrimagnitic at low temperature, while the nonstoichiometric FeTiO with the R3̄c symmetry were antiferromagnetic at room temperature. © 2003 Elsevier B.V. All rights reserved. 3+λ 2 3 3+λ 2 2 2 3+λ 2 3+λ 2+ 3+

DOI： 10.1016/j.jmmm.2003.12.793

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Language：Japanese   Publisher：日本材料学会  

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Human beings have been using "bengara" (α-Fe O ) as red pigment ever since ancient times. As for Japan, the first artificial "bengara" was manufactured at Fukiya town in 1707, and it was mainly used for red painting of porcelain and other objects for about 300 years. However this "Fukiya bengara" cannot be manufactured anymore because of the environment pollution in spite of eagerness of potters to use it for producing bright yellowish red. At first step, we characterized traditional "Fukiya bengara" and found that α-Al O existed. It is probably due to the formation of Al substituted α-Fe O . Then next step, we prepared red pigment of Fe O -Al O system to investigate the Al substitution effect, by using both solid-state and polymerized complex methods. The red tone color depended on the particle size; the yellowish red pigment had the smallest size. Al substitution seemed to suppress the grain growth of hematite. The red tone color was controllable with the amount of Al substitution. α-(Fe Al ) O prepared at 1000°C for 2 hours presented as bright yellowish red color as that of "Fukiya Bengara". 2 3 2 3 2 3 2 3 2 3 0.9 0.1 2 3

DOI： 10.2497/jjspm.50.1062

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Well-crystallized Ba Zn Fe O (Zn -Y) films with high c-axis oritentation were successfully formed on Ag substrates at low temperature by the polymeric precursor method. A precursor solution with stoichiometric Ba , Zn , and Fe ions was deposited on the substrates by a dip-coating. The films were then heat-treated at temperatures ranging from 700 to 900°C. The crystallization process of c-axis-oriented Zn -Y films occurred at the considerably low temperature of 750°C, though a small amount of spinel oxides contaminated them. The films had hexagonal grain structures which were developed by increasing the heat-treatment temperature. Magnetization curves of the Zn -Y film heated at 900°C clearly indicated that the film had large in-plane magnetic anisotropy and had small in-plane coercivity. 2 2 12 22 2 2 2 2+ 2+ 3+

DOI： 10.1557/JMR.2001.0338

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CoFe O /α-Fe O (ferrimagnetic/antiferromagnetic) bilayered films were prepared on α-Al O (102) single-crystalline substrates by helicon plasma sputtering. A well-crystallized epitaxial α-Fe O (102) layer was formed on the substrate, while CoFe O grown on α-Fe O (102) was a polycrystalline layer with a (100)-preferred orientation. The α-Fe O (102) films without CoFe O layers clearly showed a spin-flip transition at about 400 K. The spins aligned perpendicular to the film plane at room temperature changed their direction within the film plane above 400 K. However the α-Fe O base layers of CoFe O /α-Fe O bilayered films did not show any spin-flip transition. The CoFe O layer on α-Fe O had a large in-plane magnetic anisotropy, while the spin axis of the α-Fe O (102) base layer was directed perpendicular to the film plane. The magnetization of ferrimagnetic CoFe O layers was coupled perpendicularly to the spin axis of antiferromagnetic α-Fe O layers due to the exchange coupling at the interface between CoFe O and α-Fe O . 2 4 2 3 2 3 2 3 2 4 2 3 2 3 2 4 2 3 2 4 2 3 2 4 2 3 2 3 2 4 2 3 2 4 2 3

DOI： 10.1557/proc-674-t1.10

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Ni-Zn ferrite/SiC sintered composite was prepared as electromagnetic wave absorber through pre-ceramics method and subsequent annealing at 1273 K. Amorphous SiC particles dispersed uniformly in Ni-Zn ferrite matrix and the density of the composites decreased with increasing the amount of SiC particles. The absorption characteristics of the sintered composite were found to depend upon the amount of SiC particles. The matching frequency of the composites shifted toward higher frequency, from about 100 MHz to 1 GHz, with increasing the amount of SiC particles.

DOI： 10.2497/jjspm.47.927

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Language：Japanese   Publisher：Funtai Funmatsu Yakin Kyokai  

Ni-Zn ferrite/SiC sintered composite was prepared as electromagnetic wave absorber through pre-ceramics method and subsequent annealing at 1273 K. Amorphous SiC particles dispersed uniformly in Ni-Zn ferrite matrix and the density of the composites decreased with increasing the amount of SiC particles. The absorption characteristics of the sintered composite were found to depend upon the amount of SiC particles. The matching frequency of the composites shifted toward higher frequency, from about 100 MHz to 1 GHz, with increasing the amount of SiC particles.

DOI： 10.2497/jjspm.47.927

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The effects of electrochemical removal reaction of lithium from the Li-doped Bi-2212 phase on its structure and superconducting properties have been studied. Lithium was inserted into and removed from Bi₂Sr_1.5Ca_1.5Cu₂O_z through an electrochemical. method at a constant applied potential at room temperature. The original crystal symmetry, tetragonal structure, was maintained and any secondary phase was not formed throughout the electrochemical reactions. Lattice parameter c of the doped samples, Li_xBi₂Sr_1.5Ca_1.5Cu₂O_z, decreased and Tc changed reversibly as the lithium content x decreased, It reveals that the electrochemical reactions were intercalation/deintercalation of the Bi-2212 phase with lithium.

DOI： 10.2497/jjspm.45.666

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Effects of electrochemical Li-doping to the Pb-substituted Bi-2212 phase on its structural and superconducting properties were studied. Bi Pb Sr Ca Cu O was lithiated through an electrochemical method at constant applied potential at room temperature. In the electrochemically Li-doping samples, the original crystal symmetry, tetragonal structure, was maintained and any secondary phase was not formed. The amount of doped Li for Bi Pb Sr Ca Cu O was much lager than that for Bi Sr Ca Cu O at the same reaction periods. Analysed maximum Li content y for Li Bi Pb Sr Ca Cu O was found to be 0.53, which was remarkably high in comparison with y=0.37 for Li Bi Sr Ca Cu O . The lattice parameters (a,c) of Li Bi Pb Sr Ca Cu O increased continuously in a similar trend to that of Li Bi Sr Ca Cu O . Tc remains almost constant around 85K as the Li content y increased. 1.8 0.2 1.5 1.5 2 z 1.8 0.2 1.5 1.5 2 z 2 1.5 1.5 2 z y 1.8 0.2 1.5 1.5 2 z y 2 1.5 1.5 2 z y 1.8 0.2 1.5 1.5 2 z y 2 1.5 1.5 2 z

DOI： 10.2497/jjspm.44.792

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Event date： 2012.9.23 - 2012.9.28

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Applicant：国立大学法人 岡山大学

Application no：特願2011-506149  Date applied：2010.3.26

Announcement no：WO2010/110435  Date announced：2010.9.30

Patent/Registration no：特許5622718  Date registered：2014.10.3  Date issued：2014.11.12

Rights holder：国立大学法人 岡山大学

5622718

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Applicant：株式会社メイト

Application no：特願2009-137835  Date applied：2009.6.9

Announcement no：特開2010-285287  Date announced：2010.12.24

Patent/Registration no：特許5282318  Date registered：2013.6.7  Date issued：2013.9.4

Rights holder：株式会社メイト

5282318

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Applicant：国立大学法人 岡山大学

Application no：特願2007-9625  Date applied：2007.1.18

Announcement no：特開2008-177061  Date announced：2008.7.31

Patent/Registration no：特許5082095  Date registered：2012.9.14  Date issued：2012.11.28

Rights holder：国立大学法人 岡山大学

5082095

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Applicant：独立行政法人科学技術振興機構

Application no：特願2004-90660  Date applied：2004.3.25

Announcement no：特開2005-272251  Date announced：2005.10.6

Patent/Registration no：特許4485233  Date registered：2010.4.2  Date issued：2010.6.16

Rights holder：独立行政法人科学技術振興機構

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Applicant：岡山大学長

Application no：特願2002-199947  Date applied：2002.7.9

Announcement no：特開2004-43208  Date announced：2004.2.12

Patent/Registration no：特許3728505  Date registered：2005.10.14  Date issued：2005.12.21

Rights holder：国立大学法人 岡山大学

3728505

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