研究者詳細 - 難波　徳郎

論文 - 難波　徳郎

分割表示 117 件中 21 - 40 件目／全件表示 >>

Effect of Addition of Non-oxides on the Slag Corrosion Resistance of MgO-Al2O3 Refractories 査読

Keisuke Morita, Shinichi Sakida, Yasuhiko Benino, Tokuro Nanba

3RD INTERNATIONAL CONGRESS ON CERAMICS (ICC3): INNOVATION IN REFRACTORIES AND TRADITIONAL CERAMICS 18 222015 2011年

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）出版者・発行元：IOP PUBLISHING LTD

Various non-oxides, such as SiC, Si3N4 and AlN were added to MgO-Al2O3 refractory, and the effect on the slag corrosion resistance was investigated. The specimens were prepared by a spark plasma sintering (SPS) method. Slag corrosion tests were carried out using a button method under a reducing atmosphere. Improvement in corrosion resistance was confirmed for the SiC-added specimens, and the addition of nitrides, however, resulted in deterioration. Wettability was also examined, and the compositional dependence was not observed in contact angle. Quantitative relation was not found between contact angle and penetration depth.

DOI： 10.1088/1757-899X/18/22/222015

Fabrication and characterization of Er3+-doped tellurite glass waveguide by Ag+-Na+ ion-exchange method 査読

K. Kimura, S. Sakida, Y. Benino, T. Nanba

IOP Conference Series: Materials Science and Engineering 18 ( 8 ) 112018 2011年

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

The planar waveguides of 12Na2O10NbO2.525WO 353TeO2+1Er2O3 ([NbWEr]) glasses were prepared by Ag+-Na+ ion-exchange at 320-380°C for 5-30 h. The optical properties of the waveguides were characterized. Waveguiding property was successfully confirmed under all the ion-exchange conditions in this study. The thickness of the waveguides increased with increasing ion-exchange temperature and time. The minimum propagation loss of the waveguides was approximately 0.8 dB/cm at 632.8 nm. Hence, the [NbWEr] glass waveguides were considered to be promising for broadband optical amplifiers. © 2011 Ceramic Society of Japan.

DOI： 10.1088/1757-899X/18/11/112018

Phase separation of borosilicate glass containing phosphorus 査読

Y. Ohtsuki, S. Sakida, Y. Benino, T. Nanba

IOP Conference Series: Materials Science and Engineering 18 ( 8 ) 112022 2011年

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Sodium borosilicate glasses containing P2O5 and Al2O3 were prepared, and the behavior of phosphorus associated with the phase separation and the effect of Al2O 3 addition have been investigated. After the heat treatment, phase separation by spinodal decomposition was observed in the all samples. In the Al2O3-free glasses, phosphorus was preferentially distributed into B2O3-rich glass phase after the phase separation. With increasing Al2O3 content, the amount of phosphorus distributed into SiO2-rich glass phase increased. According to 31P MAS NMR measurements, in the Al2O 3-containing glasses, Q4 units free from terminal oxygen atoms were formed. It was suggested that the distribution of phosphorus depend on the PO4 units. © 2011 Ceramic Society of Japan.

DOI： 10.1088/1757-899X/18/11/112022

Coloration and Depth Distribution of Cations Electrochemically-inserted into Electrochromic WO3 Thin Films 査読

Miho Kawai, Shinichi Sakida, Yasuhiko Benino, Tokuro Nanba

3RD INTERNATIONAL CONGRESS ON CERAMICS (ICC3): ADVANCES IN ELECTRO CERAMICS 18 092039 2011年

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）出版者・発行元：IOP PUBLISHING LTD

Li+ and H+ ions were electrochemically inserted into amorphous WO3 films prepared on an ITO-coated glass substrate by an R. F. magnetron sputtering method under Ar/O-2 flow ratios of 4/1 (SP1) and 1/1 (SP2). The cation distribution was estimated indirectly by depth profiles of refractive-index obtained from prism coupler measurements and was evaluated directly by glow discharge spectrometry (GDS). H+ ions inserted were segregated only at deeper region around ITO electrode, which was independent to the preparing condition. In the case of Li+ insertion into SP1 film, Li+ ions were initially segregated at around ITO electrode, and after further insertions, they were also distributed at around the surface of WO3 film. In SP1 film, Li+ ions at around ITO electrode seemed to contribute to coloration. In SP2 film, however, Li+ ions subsequently inserted, which were uniformly distributed in the film, were only involved in coloration. The difference in depth distribution and coloration was due to the difference in atomic structure of WO3 films.

DOI： 10.1088/1757-899X/18/9/092039

Effect of ultrasonic surface treatment on the transparency and orientation of fresnoite surface crystallization 査読

A. Endo, S. Sakida, Y. Benino, T. Nanba

IOP Conference Series: Materials Science and Engineering 18 ( 8 ) 112015 2011年

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Surface crystallized glass ceramics with fresnoite (Ba2TiSi 2O8) phase were prepared by conventional heat treatment of 30BaO-20TiO2-50SiO2 glass together with ultrasonic surface treatment (UST) technique. The precursor glass was fully crystallized in a bulk form without any cracks, and the optical transparency and crystallographic orientation of the crystalline layers were evaluated by UV-Vis spectroscopy and XRD diffraction analyses, respectively. These properties were both enhanced significantly by applying UST using fresnoite/water suspension before the crystallization process, which is advantage for nonlinear optical applications of bulk glass ceramics. The effects of UST on the crystallization behavior were investigated by applying UST with various conditions. © 2011 Ceramic Society of Japan.

DOI： 10.1088/1757-899X/18/11/112015

Molecular dynamics simulation of lead borate and related glasses in multicomponent systems for low melting vitrification of nuclear wastes 査読

S. Kato, S. Sakida, Y. Benino, T. Nanba

IOP Conference Series: Materials Science and Engineering 18 ( 1 ) 022014 2011年

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Glasses based on lead oxide have excellent properties in general such as low melting point, high chemical durability and high stability of glassy form, which are suitable for the preservation of volatile nuclear wastes in a permanent vitrified form. In order to confirm the long-term performance of lead borate based glasses it is necessary to establish dissolution and diffusion processes based on a reliable model of the glass structure. In the present study molecular dynamics (MD) simulation of lead borate based glasses was carried out introducing a dummy negative point charge to reproduce asymmetric PbO n units. Parameters for the dummy charge were optimized based on the comparison between calculated radial distribution function and experimental one. Asymmetric coordination around Pb, for example trigonal bipyramid, was successfully reproduced in the MD simulated binary and ternary glass models. The simple model using the dummy charge was confirmed to be valid for further simulations of multicomponent glasses containing nuclear wastes and heavy elements. © 2011 Ceramic Society of Japan.

DOI： 10.1088/1757-899X/18/2/022014

Phase separation of borosilicate glass containing sulfur 査読

Keiji Saiki, Shinichi Sakida, Yasuhiko Benino, Tokuro Nanba

JOURNAL OF THE CERAMIC SOCIETY OF JAPAN 118 ( 1379 ) 603 - 607 2010年7月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：CERAMIC SOC JAPAN-NIPPON SERAMIKKUSU KYOKAI

A 10Na(2)S center dot 30B(2)O(3)center dot 60SiO(2) (mol %) glass was prepared, and the changes in glass structure and chemical state of sulfur caused by phase separation were investigated. In the as-prepared and heat-treated glasses, sulfur was present as S2- anion and polysulfide S2- and S3- anions, and Si-S and B-S bonds were not confirmed. A phase separation by spinodal decomposition was observed after heat-treatment, where sulfur was preferentially distributed to borate-rich phase. Even after the phase separation, formation of non-bridging oxygen was not recognized. The preferential distribution of sulfur anions in the present glass was explainable on the basis of the change in population of sodium ions, which compensated the negatively-charged sulfur anions. (C)2010 The Ceramic Society of Japan. All rights reserved.

DOI： 10.2109/jcersj2.118.603

FURTHER DEVELOPMENT OF IODINE IMMOBILIZATION TECHNIQUE BY LOW TEMPERATURE VITRIFICATION WITH BiPbO2I 査読

Atsushi Mukunoki, Tamotsu Chiba, Yasuhiro Suzuki, Kenji Yamaguchi, Tomofumi Sakuragi, Tokuro Nanba

PROCEEDINGS OF THE 12TH INTERNATIONAL CONFERENCE ON ENVIRONMENTAL REMEDIATION AND RADIOACTIVE WASTE MANAGEMENT 2009, VOL 1 329 - 334 2010年

担当区分：最終著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）出版者・発行元：AMER SOC MECHANICAL ENGINEERS

The authors describe progress in the development of low temperature vitrification with BiPbO2I (BPI) as a promising immobilization technique by which Iodine-129 is recovered by BiPbO2NO3 to form BPI, and then solidified into a lead-boron-zinc glass matrix (PbO-B2O3-ZnO) using a low temperature vitrification process. The microscopic structure of BPI glass was analyzed by various analytical techniques, such as XRD (X-ray diffraction), NMR (nuclear magnetic resonance analysis), and XPS (X-ray photoelectron spectroscopy), using several types of glass samples. The results obtained provide structural information on key elements in BPI glass and can be applied for modeling the structure of the BPI glass, simulated by molecular dynamics. The previous work suggested that the leaching behavior of iodine from BPI glass depended upon the chemical conditions of the solution. Further leaching tests using solutions under varying conditions were carried out in order to predict mechanisms of iodine leaching. Normalized elemental mass loss values of iodine in simulated seawater and bentonite pore water are almost the same as those of boron, showing that iodine dissolves congruently with BPI glass, whereas iodine dissolves incongruently in Ca(OH)(2) solutions of pH 9 and 11. To demonstrate the feasibility of the BPI vitrification process, recovery tests of iodine from spent iodine filters were conducted and a prototype melting furnace was developed for scale-up tests of glass sample. It was found that more than 95% of iodine can be recovered from the spent iodine filter and that the prototype furnace can produce approximately 0.5 liters of homogeneous glass.

Chemical recycling of municipal waste slag by using phase separation 査読

Tokuro Nanba, Yutaro Kuroda, Shinichi Sakida, Yasuhiko Benino

JOURNAL OF THE CERAMIC SOCIETY OF JAPAN 117 ( 1371 ) 1195 - 1198 2009年11月

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：CERAMIC SOC JAPAN-NIPPON SERAMIKKUSU KYOKAI

A chemical recycling method by using phase separation was applied to municipal waste slags. Glasses were prepared from incineration ash and ash-melted slag, where B2O3 was added to promote phase separation. The glasses were heat-treated at temperatures higher than their glass transition temperatures, and they were soaked in hydrochloric acid, leaching CaO, Fe2O3, K2O, and S. Transparent and colorless solids containing ca. 80 mass% of SiO2 were successfully obtained as residues. It was suggested that phase separation took place not in the heat-treatment but in the vitrification process, and further characterizations are however required to investigate the phenomena at microscopic levels in the recycling processes. (C) 2009 The Ceramic Society of Japan. All rights reserved.

DOI： 10.2109/jcersj2.117.1195

Molecular orbital calculation of the Si-29 NMR chemical shift in borosilicates: the effect of boron coordination to SiO4 units 査読

T. Nanba, Y. Asano, Y. Benino, S. Sakida, Y. Miura

PHYSICS AND CHEMISTRY OF GLASSES-EUROPEAN JOURNAL OF GLASS SCIENCE AND TECHNOLOGY PART B 50 ( 5 ) 301 - 304 2009年10月

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：SOC GLASS TECHNOLOGY

Borosilicate cluster models were constructed, and the Si-21 NMR chemical shift was estimated by molecular orbital calculations. For Q(4) species (an SiO4 unit consisting of four bridging oxygen atoms), a higher frequency shift was confirmed due to the replacement of the surrounding SiO4 with BO4 units, and for Q(4) species associated with more than one BO4 unit, the chemical shifts were nearly identical to those for Q(3) species (an SiO4 unit including one nonbridging oxygen) in alkali silicates. The chemical shifts of Q(4) species in borosilicates were interpreted in terms of the change in bond angle of Si-O-(Si,B4) bridges. A change in chemical shift anisotropy of Q(4) species was also found. The Q(4) species associated with two BO4 units indicated an anisotropy maximum, which was smaller than the anisotropy of Q(3) species.

Correlation between basicity and coordination structure in borosilicate glasses 査読

Y. Tanaka, Y. Benino, T. Nanba, S. Sakida, Y. Miura

PHYSICS AND CHEMISTRY OF GLASSES-EUROPEAN JOURNAL OF GLASS SCIENCE AND TECHNOLOGY PART B 50 ( 5 ) 289 - 293 2009年10月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：SOC GLASS TECHNOLOGY

Various quaternary borosilicate glasses in the general system M(2)O-M'O-Al(2)O(3)-B(2)O(3)SiO(2) (M=Li, Na or K; M'=Ca, Sr or Ba) were prepared, and the concentration of four-fold coordinated boron (B4) atoms was determined using (11)B magic angle spinning NMR. Regression analyses were performed to predict the B4 fraction, in which B4 fraction and glass basicity were used as dependent and independent variables, respectively. Except for Al(2)O(3)-containing glasses, regression formulae giving high correlation coefficients were successfully obtained by using B4/(B+Sixf) (where f is a tunable coefficient) as the dependent variable. As for the glasses containing Al(2)O(3), however, the necessity of a different dependent variable was indicated.

Molecular orbital calculation of the Si NMR chemical shift in borosilicates: The effect of boron coordination to SiO4 units

T. Nanba, Y. Asano, Y. Benino, S. Sakida, Y. Mima

Physics and Chemistry of Glasses: European Journal of Glass Science and Technology Part B 50 ( 5 ) 301 - 304 2009年10月

記述言語：英語掲載種別：研究論文（学術雑誌）

Borosilicate cluster models were constructed, and the 29Si NMR chemical shift was estimated by molecular orbital calculations. For Q 4 species (an SiO4 unit consisting of four bridging oxygen atoms), a higher frequency shift was confirmed due to the replacement of the surrounding SiO4 with BO4 units, and for Q4 species associated with more than one BO4 unit, the chemical shifts were nearly identical to those for Q3 species (an SiO4 unit including one nonbridging oxygen) in alkali silicates. The chemical shifts of Q4 species in borosilicates were interpreted in terms of the change in bond angle of Si-O-(Si,B4) bridges. A change in chemical shift anisotropy of Q4 species was also found. The Q4 species associated with two BO4 units indicated an anisotropy maximum, which was smaller than the anisotropy of Q3 species.

Studies on the characterization of sulfur and coloration in borosilicate glasses 査読

Taro Asahi, Susumu Nakayama, Tokuro Nanba, Hajime Kiyono, Hiroshi Yamashita, Takashi Mackawa

JOURNAL OF CERAMIC PROCESSING RESEARCH 9 ( 4 ) 401 - 406 2008年8月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：KOREAN ASSOC CRYSTAL GROWTH, INC

Ternary alkali borosilicate glasses containing sulfur were prepared by a conventional melt quenching method, and their chemical bonding states were investigated based on XPS and Si-29,B-II MAS-NMR measurement. The glass samples changed in color from blue to reddish brown due to the state of the sulfur and their glass compositions. From S2p photoelectron spectra, it can be seen that the sulfur exists with a negative charge in the glass. The forming of non-bridging oxygen components was observed from O1s photoelectron spectra of the glasses, which colored to brown and reddish brown. Furthermore, a signal from silicon atoms coordinated to the sulfur was detected in these glasses by the Si-29 MAS-NMR measurement. From these results, it is considered that sulfur atoms bonded silicon atoms at the forming range of the non-bridging oxygen component.

Chemical recycling of inorganic wastes by using phase separation of glass 査読

Tokuro Nanba, Shuhei Mikami, Takuya Imaoka, Shinichi Sakida, Yoshinari Miura

JOURNAL OF THE CERAMIC SOCIETY OF JAPAN 116 ( 1350 ) 220 - 223 2008年2月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：CERAMIC SOC JAPAN-NIPPON SERAMIKKUSU KYOKAI

A chemical recycling process using phase separation of glass was applied to a granulated blast furnace slag with high CaO content. Glasses were prepared by adding B2O3 to the slag in order to promote phase separation, and the glasses were heat-treated above glass transition temperature. In the subsequent acid-treatment, however, gelation due to the elution of SiO2 phase containing CaO occurred, not obtaining high SiO2 Solids. Then, pretreatment was introduced to reduce CaO content in slag, where the raw slag was briefly washed in acid. The slag glasses prepared from the pretreated slag were commonly phase-separated by heat-treatment regardless of B2O3 content. After subsequent acid-treatment, colorless insoluble solids were successfully recovered. The end products consist of 70-90 mass% SiO2, and coloring ions such as Mn, Fe and Cr were almost completely removed from the slag glasses. Reutilization as raw materials for glass is expected.

DOI： 10.2109/jcersj2.116.220

Optical properties of Er3+-doped tungsten tellurite glass waveguides by Ag+-Na+ ion-exchange 査読

Shinichi Sakida, Tokuro Nanba, Yoshinari Miura

OPTICAL MATERIALS 30 ( 4 ) 586 - 593 2007年12月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ELSEVIER SCIENCE BV

The planar waveguides of 12Na(2)O center dot 35WO(3) center dot 53TeO(2) center dot 1Er(2)O(3) glass (in mol%) were prepared by Ag+-Na+ ion-exchange at 300-360 degrees C for 5-30 h. The effective mode indices and propagation losses of the waveguides were measured at the wavelengths of 473, 632.8, 983.1 and 1548 nm by means of a prism coupler technique. The waveguide depths from glass surface increased with increasing ion-exchange temperature and time. The diffusion parameters such as diffusion coefficient and activation energy were calculated on the basis of an Arrhenius temperature dependence of the diffusion coefficient of Ag+ ions in the ion-exchanged glasses. The propagation losses of the waveguides were 5.04-6.64, 2.70-4.77, 5.44-6.73 and 7.32-8.31 dB/cm in the first half in the propagation distance from 0 to 3.0 cm and 3.52-4.82, 1.92-2.99, 3.78-5.06 and 3.91-5.15 dB/cm in the latter half at 473, 632.8, 983.1 and 1548 nm, respectively. The relationship between the optical properties of the waveguides and the ion-exchange conditions is discussed. (c) 2007 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.optmat.2007.01.010

Sintering of Al2O3-Cr2O3 powder prepared by sol-gel process 査読

Motonari Fujita, Keisuke Inukai, Shinichi Sakida, Tokuro Nanba, Junji Ommyoji, Akira Yamaguchi, Yoshinari Miura

Zairyo/Journal of the Society of Materials Science, Japan 56 ( 6 ) 526 - 530 2007年6月

記述言語：英語掲載種別：研究論文（学術雑誌）

The sol-gel method was applied to create Al2O 3-Cr2O3 ceramics using aluminum ethylacetoacetate diisopropylate and chromium (III) chloride hexahydrate as starting materials. In the calcination at 600-1200°C it was found that the grains of Cr2O3-rich solid solution grew when they were exposed to the surrounding Al2O3-rich amorphous particles. The composition of the powders obtained by the sol-gel process changed with calcining temperature. Cr2O3-rich solid solutions firstly crystallize at low temperature and the composition of the crystallites changes as the crystals grow and react with the surrounding Al2O 3-rich phases. The final sintered bodies fired under an Ar atmosphere showed higher relative densities as compared with those fired in air. A dense sintered body was not obtained when abnormal grains grew when calcining occurred. © 2007 The Society of Materials Science.

DOI： 10.2472/jsms.56.526

Refractive-index profiles and propagation losses of Er3+-doped tungsten tellurite glass waveguide by Ag+-Na+ ion-exchange 査読

S. Sakida, T. Nanba, Y. Miura

MATERIALS LETTERS 60 ( 28 ) 3413 - 3415 2006年12月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ELSEVIER SCIENCE BV

The planar waveguide of 12Na(2)O-35WO(3)(.)53TeO(2)lEr(2)O(3) glass (in mol%) was prepared by Ag+-Na+ ion-exchange at 330 degrees C for 5 h. The effective mode indices and propagation losses of the waveguide at the wavelengths of 473, 632.8, 983.1 and 1548 nin for TE and TM modes were measured by means of a prism coupler technique. The results were compared with those of a planar waveguide of the tungsten tellurite glass without Er3+ ions. Especially, the propagation losses of ion-exchanged tellurite glass waveguides were estimated for the first time to the best of our knowledge. (c) 2006 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.matlet.2006.03.024

Structural change around Si atoms in P2O5-SiO2 binary glasses before and after annealing by Si-29 MAS NMR spectroscopy 査読

Shinichi Sakida, Tokuro Nanba, Yoshinari Miura

CHEMISTRY LETTERS 35 ( 11 ) 1268 - 1269 2006年11月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：CHEMICAL SOC JAPAN

The Si-29 MAS NMR spectra of P2O5-SiO2 binary glasses were measured before and after annealing to examine the local structure around Si atoms in the glasses. The glasses were composed of SiO6 octahedra and Q(4) (SiO4 tetrahedra with four bridging oxygens). By increasing the P2O5 content, the fractions of SiO6 octahedra increased and those of Q4 decreased. The fractions of SiO6 octahedra increased by 6-8% in the range of 29.7 to 47.4 mol % P2O5 by annealing for 5 h. This result was found for the first time in binary glasses. On the basis of the results obtained, the local structure around Si atoms in the glasses and the structural change by annealing are discussed.

DOI： 10.1246/cl.2006.1268

硫黄含有ホウケイ酸塩ガラスの作製と局所構造解析査読

朝日太郎, 中山享, 三浦嘉也, 難波徳郎, 山下浩, 前川尚

J. Ceram. Soc. Japan 114 ( 1332 ) 697 - 704 2006年8月

リン酸塩結合材を用いたパッチング耐火物の作業性（可塑性）の低下機構査読

崎田真一, 山本祐一, 難波徳郎, 三浦嘉也, 林徹浩, 山口明良

材料 55 ( 7 ) 670 - 674 2006年7月

　前のページ - 次のページ　

1
2
3
4
5
6