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The influence of molar volume, polarizability of oxide ion, and Ols binding energy on the refractive index was investigated for the various binary tellurite glasses. In the combination with P2O5, B 2O3, and Al2O3, the refractive index was linearly correlated to molar volume, polarizability, and Ols binding energy. In alkali tellurite systems, the refractive index was weakly related to molar volume and polarizability. A linear correlation was found between the refractive index and Ols binding energy, but the correlation was opposite to the case for P2O5, B2O3, and Al 2O3. It was commonly confirmed in the tellurite glasses that the refractive index was dominantly dependent on the optical band gap. Ab-initio molecular orbital calculations revealed that the LUMO levels were characterized by the structural units in tellurite glasses. In TeO4 tbp unit, the LUMO levels were formed by the anti-bonding overlaps of Te5p and O2p orbitals in the axial Te-O bonds, resulting in the narrow HOMO-LUMO gap. In TeO3+1 unit, larger contribution of Te5p orbital was confirmed in the LUMO levels, resulting in the wider gap. It was finally concluded that the structural change from TeO4 tbp to TeO3 tp via TeO 3+1 units widened the energy gap, resulting in the decrease in the refractive index.

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Various heavy metal oxide glasses were prepared, and the optical properties of Pr and Tm ions were investigated. Among the glasses, the infrared emissions of Pr: 1.3 μm and Tm: 1.46 μm were successfully observed in Bi 2O3-containing glasses, and such phenomena were due to the high refractive index and low phonon energy of the Bi2O3 glasses. According to the results from the Judd-Ofelt analyses, the radiative transition probabilities A of Pr: 1G4→ 3H5 transition at 1.3 μm were dependent on the refractive index n and the line strength of electric dipole transition S ed. On the other hand, A of Tm: 3H4→ 3F4 transition at 1.46 urn mainly depended on n. The Pr: 1G4 level was successfully populated by Pr/Yb co-doping, resulting in the enhancement of Pr: 1.3 μm emission. In Tm3+ doped K2O-Bi2O3-Ga2O3 glasses, the 1.46 μm emission increased in intensity with increasing Tm 2O3 content.

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It was confirmed that the divalent cations, Zn2+ and Cu 2+ were electrochemically inserted into amorphous WO3 films prepared by r.f.-magnetron sputtering method. Coloration of the films was also observed, and the films were, however, bleached gradually. The bleaching mechanism was discussed based on the ab-initio molecular orbital calculations, in which Li+ or Zn2+ ions were introduced into the WO 3 frameworks. In the case of Zn insertion, electrons were trapped in a non-bonding Zn 4s orbital just below the conduction band. It was finally concluded that in the films with distorted WO3 frameworks, Zn 4s orbital was mingled in the conduction band and electrons were free to be transferred between W6+ and W5+. As the structural relaxation progressed, electrons were gradually trapped in Zn 4s orbital, and the films were finally bleached.

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The planar waveguides of 12Na2O·10MgO·25GeO 2·53TeO2·1Er2O3 (MgGeEr) and 12Na2O·35WO3·53TeO 2·1Er2O3 (WEr) glasses (in mol%) were prepared by Ag+-Na+ ion-exchange. The Ag +-Na+ ion-exchange was performed by immersing the glasses in 1.0AgNO3·49.5NaNO3·49.5KNO3 melt (in mol%) at 300 - 360°C for 5 - 30 hours. The waveguide of WEr glass showed higher light scattering than that of MgGeEr glass under the same ion-exchange condition, indicating that the extent of light scattering by the waveguide surface of an ion-exchanged tellurite glass is dependent on the tellurite glass system. The effective mode indices and propagation losses of the waveguides at the wavelengths of 473, 632.8, 983.1 and 1548 nm for TE and TM mode were measured by means of a prism coupler technique. As a result, it was found that the ion-exchanged layer in the waveguide was optically isotropic and that the depth of the waveguide increased with increasing ion-exchanged 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 glass. The propagation losses of the MgGeEr and WEr glass waveguides ion-exchanged at 330°C for 5 hours for TE and TM modes were about 6, 4, 6 and 7 - 8 dB/cm at 473, 632.8, 983.1 and 1548 nm, respectively. The propagation losses of ion-exchanged tellurite glass waveguides were estimated for the first time to the best of our knowledge.

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We investigated infrared luminescent phenomena in bismuth lanthanum borate glasses. In bismuth lanthanum borate glasses, the absorption peak was observed at 460 nm. The absorption peak was observed only when the glass was melted in Al2O3 crucible, whereas no peak was seen in the case of Pt crucible and the case of Al2O3 doped sample melted in Pt crucible. The infrared emission peak was observed at 1300 nm excited at 800nm. Life time at 1300 nm was 56.7 μs. We suggested that the absorption and infrared emission have been associated with pentavalent Bi ions in the glasses. It was estimated by La 3d XPS spectra and ESR spectra.

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Local structure around oxygen is directly elucidated by 17O nuclear magnetic resonance (NMR). However, the 17O NMR spectra in borosilicate glasses are quite complicated, and hence the assignments of the peaks have been empirically done. In the present study, 17O NMR parameters for the various oxygen sites in the borosilicate system were obtained from the ab-initio molecular orbital calculations using the Gaussian03 programs. As for the oxygen atoms in SiOSi, SiOB[3], and B[3]OB[3] bridging bonds (B[n]: n-fold coordinated boron), the isotropic chemical shift δiO decreased with increasing the bond angle. The oxygen atoms coordinated by B[4] as SiOB[4], B[3]OB[4], and B[4]OB[4] bridges showed weak dependency in δiO against the bond angle, and B[4]OB[4] showed a maximum in δiO at 150°. The quadrupole coupling constant Cq of all the bridging oxygens increased with increasing the bond angle. When the oxygen atoms in SiOB[4], B[3]OB[4] bridges were coordinated by Na ion, δi O decreased by 5 ∼ 10 ppm. The oxygen atoms in trimeric ring clusters showed different δiO from dimeric clusters, indicating that δiO was also influenced by the second neighboring cations. The order of δiO was expected as SiOSi &lt
SiOB[4] &lt
SiOB[3] &lt
B[4]OB[4] &lt
B[3]OB[4] &lt
B[3]OB[3], which was in accordance with the order of bond covalency.

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

The structure of MO-TeO2 (RI Mg Zn, Sr, Ba and Pb) glasses has been studied by means of Te-125 static NMR technique. The fraction of TeO4, trigonal bipyramid (tbp), N-4 decreased and that of TeO3 trigonal pyramid (tp), N-3 increased almost linearly up to 33.3 mol% MO and rapidly in the range of 33.3 to 40 mol% MO, with increasing MO content, It was found that the glasses containing MO in the range of 40 to 45 mol% MO consisted only of TeO3 tp. On the basis of the structural model proposed in a previous paper, the fractions of TeO4 tbp without a non-bridging oxygen (NBO) atom, TeO4/2 (N-4(0)), TeO4 tbp with an NBO atom, O-3/2 Te-O- (N-4(-)) and TeO3 tp with two NBO atoms, O1/2Te(= O)-O- (N-3(-)) were calculated. The structural change for MO-TeO2 glasses in the range of 0 to 33.3 mol% MO could be well represented by the model previously proposed for alkali tellurite binary glasses. A new model which represents the structural change for MO-TeO2 glasses containing more than 33.3 mol% MO has been proposed.

DOI： 10.2109/jcersj.107.395

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Language：English   Publisher：CERAMIC SOC JAPAN-NIPPON SERAMIKKUSU KYOKAI  

Electronic structure of amorphous niobium oxide prepared by a sputtering method was investigated based on optical absorption and photoelectron spectroscopies. In the valence band photoelectron spectra, broad peaks without any characteristic components were observed. Then, theoretical calculations based on a density functional theory were performed to interpret the experimental spectra by using three Nb2O5 polymorphs. Among the polymorphs, M-phase with tetragonal structure showed better reproducibility than the other B- and R-phases with monoclinic structure. It was finally concluded that the amorphous niobium oxide had a similar electronic structure to M-Nb2O5, and it was supposed that the broad feature in the photoelectron spectra was due to the broad distribution of Nb-O bonds in NbO6 polyhedra, which was characteristic in M-Nb2O5. (C) 2016 The Ceramic Society of Japan. All rights reserved.

DOI： 10.2109/jcersj2.16180

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Language：English   Publisher：Elsevier B.V.  

A chemical recycling process of inorganic wastes has been developed, where after vitrifying wastes, the glasses were heat-treated and soaked in an acid, obtaining colorless and transparent SiO2-abundant glasses. In the present study, distribution behavior of the constituents such as Si, P, Ti, Al and so on present in a municipal waste slag was examined. According to compositional analyses, the recovered solids after acid treatment consisted of SiO2, P2O5 and TiO2, suggesting the preferential distribution of P and Ti atoms into SiO2-rich phase during phase separation. In high resolution microscopic analyses, however, it was observed that P and Ti atoms were distributed separately from Si atoms, and they were present in the different particles insoluble in the acid. It was finally concluded that the insoluble solids were produced by a dissolution-reprecipitation process, that is, once all the constituents of the vitrified slag were dissolved in the acid, P2O5 and TiO2 coprecipitated as particles, and TiO2 was indispensable for the precipitation of P2O5. SiO2 also precipitated as particles separately from P- and Ti-containing particles. © 2013 The Ceramic Society of Japan and the Korean Ceramic Society.

DOI： 10.1016/j.jascer.2013.03.003

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Sodium borosilicate glasses containing phosphorus were prepared, and the effect of Al2O3 and TiO2 addition on the distribution behavior of phosphorus atoms associated with the phase separation was investigated. After heat treatment, a phase separation by the spinodal decomposition was commonly confirmed by SEM observation. In the additive-free sample, phosphorus was preferentially distributed into B2O3-rich phase after the phase separation, and after adding Al2O3 or TiO2, the amount of phosphorus distributed into SiO2-rich phase increased. It was also suggested that TiO2 had a stronger influence on the phosphorus distribution into SiO2-rich phase than Al2O3. P-31 MAS-NMR revealed that most of phosphorus atoms in the additive-free glass were present in PO4 units consisting of two terminal oxide ions, and the terminal oxide ions decreased and increased after the additions of Al2O3 and TiO2, respectively. It was suggested that this structural change brought about a change in the distribution of phosphorus. (C) 2012 The Ceramic Society of Japan. All rights reserved.

DOI： 10.2109/jcersj2.120.490

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SnO-P2O5 glasses have high refractive index and low glass transition temperature but have poor water durability. To improve water durability, NbO2.5 was added to SnO-P2O5 glasses, preparing SnO-NbO2.5-P2O5 glass. It was found that addition of only 4 mol % NbO2.5 was enough to achieve significant improvement of water durability, and at the same time, no degradation in thermal and optical properties was observed. (C)2012 The Ceramic Society of Japan. All rights reserved.

DOI： 10.2109/jcersj2.120.530

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Surface crystallized glass-ceramics with nonlinear optical Bi2ZnB2O7 (BZB) crystals were prepared by ultrasonic surface treatment (UST) followed by crystallization heat treatment for stoichiometric glass with a composition of 33.3Bi(2)O(3)-33.3ZnO-33.3B(2)O(3). According to the surface XRD measurements and microscopic observations, UST technique was found to be quite effective for lower temperature precipitation of BZB, indicating the ability of crystallization control of the target phase, such as phase selectivity, small size of precipitates, high orientation and their morphology. After the optimization of the process condition parameters for improving transparency and suppressing deformation of the sample, the effective optical nonlinearity of the transparent surface crystallized glass-ceramics was estimated as 0.7 pm/V. (C)2012 The Ceramic Society of Japan. All sights reserved.

DOI： 10.2109/jcersj2.120.509

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Multiple regression analyses were applied to the prediction of glass structures, such as O 1s binding energy and fraction of fourfold coordinated boron atoms, N-4. In the case of linear combination of the content of glass constituents, an acceptable prediction accuracy was obtained for O 1s binding energy, and as for N-4, however, a poor agreement was observed between the prediction and measurement. After introducing quadratic and cubic interaction terms into the regression formula, a drastic improvement was achieved in the prediction of N-4. Some regression coefficients were dependent on basicity of each glass constituent, suggesting the feasibility of prediction for the glasses containing novel constituents whose regression parameters have never been determined. (C)2012 The Ceramic Society of Japan. All rights reserved.

DOI： 10.2109/jcersj2.120.98

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Other Link： http://ousar.lib.okayama-u.ac.jp/48218

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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

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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

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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

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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

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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

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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

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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

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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

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Language：English   Publisher：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.

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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.

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Other Link： http://eprints.lib.okayama-u.ac.jp/42677

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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

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The preparation of SnO-B(2)O(3) and SnO-SiO(2) glasses by melting in Ar atomosphere was performed. The prepared SnO-B(2)O(3) glasses were large enough to measure optical properties whereas the vitrification in SnO-SiO(2) system was very difficult. PbO-B(2)O(3) and BiO1.5-B(2)O(3) glasses were also prepared for comparison with SnO-B(2)O(3) glasses. The densities, glass transition temperatures, and optical properties such as refractive indices, dispersion, and transmission spectra of SnO-B(2)O(3), PbO-B(2)O(3), and BiO(1.5)-B(2)O(3) glasses were measured. On the basis of the obtained results, the potential for SnO-B(2)O(3) glasses as lead-free glasses is particularly discussed from the viewpoint of optical properties.

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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

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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

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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

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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

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The hardening mechanism of refractory patching materials with a phosphate binder was investigated by means of 31P static and magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy. Ten refractory patching materials were made of refractory powders of SiO 2 and fused alumina and five mixed solutions of phosphoric acid and aluminum biphosphate as phosphate binders. 31P static and MAS NMR spectra were measured of five phosphate binders and twenty soft and hard refractory patching materials, respectively, to reveal the local structure around P atoms. The 31P static and MAS NMR spectra revealed that PO 4 tetrahedra in the phosphate binders have no P-O-P linkage between PO 4 tetrahedra and that as the patching materials become hard, the ratio of PO 4 tetrahedra with bridging oxygens increases, respectively. This result suggests that the hardening of the patching materials is caused by the condensation of the phosphate binder. But the ratio of PO 4 tetrahedra with bridging oxygens was not enough to form the network by P-O-P linkage between PO 4 tetrahedra. On the basis of these results, the hardening mechanism of refractory patching materials with a phosphate binder is proposed.

DOI： 10.2472/jsms.55.670

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Language：Japanese  

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Language：English   Publishing type：Book review, literature introduction, etc.   Publisher：CERAMIC SOC JAPAN-NIPPON SERAMIKKUSU KYOKAI  

O1s binding energy measured by X-ray photoelectron spectroscopy (XPS) is candidate as a new tool to determine a new scale of Lewis basicity of oxide ions in glass. Some mathematical expressions for the basicity or XPS chemical shift, such as charge parameter and optical basicity, were compared with the experimental O1s binding energy in binary alkali oxide glasses. The expressions so far in use needed some modification in parameters. A new empirical expression introduced in this paper gives a new concept and universal scale of basicity.

DOI： 10.2109/jcersj.113.44

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Language：English   Publisher：CHEMICAL SOC JAPAN  

Cd-113 magic-angle spinning (MAS) and static NMR spectra were measured of fourteen kinds of chlorocadmate glasses to reveal the chlorine coordination environments around Cd2+ in the glasses in detail. The spectra of the glasses suggest that the glass structures are mainly composed of infinite double-chains of edge-shared CdCl6 octahedra, being independent of the CdCl2 content and the kinds of chlorides except for CdCl2. Cd-113 MAS and static NMR spectroscopies enabled us to reveal not only chlorine coordination number of Cd but also linkage manners between CdCl6 octahedra in the glasses.

DOI： 10.1246/cl.2003.786

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Language：English   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

Glass transition temperatures (T-g), crystallization temperatures (T-x), and Cd-113 magic-angle spinning (MAS) NNIR spectra of the chlorocadmate, bromocadmate, and bromochlorocadmate glasses and the CdCl2, CdBrCl, and CdBr2 crystals have been measured. The T-g and T-x, and thermal stabilities (T-x - T-g) decreased with increasing Br-content. No enhancement of (T-x - T-g) of bromochlorocadmate glasses by anion-mixing was observed. The CdCl2 and CdBr2 crystals gave the isotropic chemical shifts of 183 and - 24 ppm, which are assigned to the CdCl6 and CdBr6 octahedra, respectively. The isotropic chemical shifts of CdBrCl crystal (186, 166, 135, 101, 63, 25 and -21 ppm) were assigned to CdBrnCl(6-n) (n = 0-6) octahedra, respectively. It was found that the Br and Cl atoms in CdBrCl randomly occupy chlorine sites in the CdCl2 structure. The Cd-113 MAS NMR spectra revealed that the chlorocadmate, bromocadmate, and bromochlorocadmate glasses are composed of the CdCl6, CdBr6 and CdBrnCl(6-n) octahedra (n = 0-6), respectively, and that the Cd2+ in all the bromochlorocadmate glasses was more preferentially bonded to Br- than Cl-. The relationship between the thermal properties and the anion coordination environments around Cd2+ in these glasses is discussed. (C) 2003 Elsevier Ltd. All rights reserved.

DOI： 10.1016/S0038-1098(03)00447-2

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Language：English   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

Cu-63 MAS NMR spectra of CuX crystals (X = Cl, Br, and I) and CuX-based glasses (X = Cl, Br, and I) have been measured. The CuCl and CuI crystals gave the isotropic chemical shift values around 0 ppm, and the CuBr crystal, around -55 ppm. The peak positions of the chlorocuprate(I), bromocuprate(I), and iodocuprate(I) glasses were very close to those of the CuX crystals, respectively. This result indicates that these glasses mainly consist of CuX4 tetrahedra (X = Cl, Br, and I). The halogen coordination environments around Cu+ in bromochlorocuprate(I) glasses were dependent on the kind of modifying cation and the Br-/(Cl- + Br-) ratio. The bromochlorocuprate(I) glasses were mainly composed of CuClmBr4-m or CuClnBr4-n tetrahedra (m = 0, 1, 2, and 4; n = 0, 1, and 4). (C) 2002 Elsevier Science Ltd. All rights reserved.

DOI： 10.1016/S0025-5408(02)00977-7

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Language：English   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

Cd-113 magic-angle spinning (MAS) and static NMR spectra are measured using 23 kinds of halogenocadmate crystals with known structures to determine the isotropic chemical shifts (delta (iso)), chemical shift anisotropies (Delta delta), and asymmetry parameters eta and then to discuss the relationship among these NMR parameters and the halide-anion co-ordination environments around Cd2+. The delta (iso(MAS)) values of halide-anion co-ordination polyhedra of Cd2+ largely change with the kind of halide-anion and the halide-anion co-ordination number, The \ Delta delta \ and eta in halogenocadmate crystals is largely dependent on the structure type of crystal, but is independent of the halide-anion co-ordination number of Cd2+. (C) 2001 Elsevier Science Ltd. All rights reserved.

DOI： 10.1016/S0022-3697(01)00091-9

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Language：English   Publisher：ELSEVIER SCIENCE BV  

(LCd)-Cd-113 magic-angle spinning (MAS) NMR spectra have been measured for glasses of 50.0CdBr(2) . xKBr . xCsBr . (50.0-2x)BaBr2 (x = 17.5 and 20.0), 40CdI(2) . 40KI . 20CsI, 50CdI(2) . gamma KI . (50-gamma )CsI (gamma = 10, 20, and 30), 60CdI(2) . 10KI . 30CsI, and (60-z)CdI2 . 40CsI . zBaI(2) (z = 0, 5 and 10) in mol% to reveal the anion co-ordination environments around Cd2+ in the glasses. The bromocadmate and iodocadmate glasses gave isotropic chemical shift values of -27 ppm and 78 similar to 121 ppm, respectively, indicating that the former and the latter glasses consist of CdBr6 octahedra and CdI4 tetrahedra, respectively. Moreover, the octahedral anion co-ordination around Cd2+ in the bromocadmate glasses has higher symmetry than that in the chlorocadmate glasses, and the iodine co-ordination environment around Cd2+ in the iodocadmate glasses is dependent on the CdI2 content, but is independent of the kind of glass-modifying cation. (C) 2001 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0022-3093(01)00729-3

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Language：English   Publisher：ELSEVIER SCIENCE BV  

Densification of glasses having different chemical-bond properties and also different structures have been examined by treating ionic ZrF4-based Buoride glasses, mixed ionic and covalent SiO2-based oxide glasses, and a covalent GeS2 sulfide glass at temperatures of about three-quarters of their respective glass-transition temperatures under pressures up to 9 GPa. The densities of GeS2 glass and silicate glasses of SiO2 contents > 50 mol% increased with increasing applied pressure. In ZrF4-based glasses and silicate glasses with SiO2 contents < 50 mol%. on the other hand, the densities increased until an applied pressure around 3 GPa. the maximum densities were measured at pressures around 3 GPa, and then decreased with increasing pressure. The pressure dependences of permanent densification observed in the latter glasses are a permanent densification that has not been reported to our knowledge. (C) 2001 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0022-3093(01)00391-X

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Language：English   Publisher：ELSEVIER SCIENCE BV  

Cd-113 magic-angle spinning nuclear magnetic resonance spectra of crystalline CdF2, KCdF3 and CdCl2 with known crystal structures and vitreous 50CdF(2). 30NaCl . (20 - x)BaF2. xBaCl(2) in mol% (x : 0, 5, 10, 15 and 20) were measured to reveal the anion-coordination environments around Cd2+ in the glasses. The isotropic chemical shifts, delta (iso) of the CdF2, KCdF3 and CdCl2 crystals locate around -226, -105 and 183 ppm, being assigned to the CdF8,CdF6, and CdCl6 polyhedra, respectively. From an analysis of the Cd-113 magic-angle spinning nuclear magnetic resonance spectra of the glasses we deduced that CdFmCln polyhedra (m not equal 0 and n not equal 0) which have not been found in crystalline compounds are present in the glasses. The peak positions and the full widths at half maxima (FWHM) in the glasses increased as BaF2 was replaced by BaCl2. This increase implies that the number of Cl- bonded to Cd2+ increases with increasing BaCl2 content and also that a variety of anion-coordination environments around Cd2+ are more distributed with increasing BaCl2-content. (C) 2001 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0022-3093(01)00374-X

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Language：English   Publisher：American Ceramic Society  

The structures of M2O3-TeO2 (M = Al and Ga) glasses have been investigated by means of 125Te, 27Al, and 71Ga NMR spectroscopies. The structural units of respective cations in M2O3-TeO2 glasses were quantitatively analyzed. The fractions of TeO4 trigonal hipyramid. AlO6 and GaO6 octahedra decreased and those of TeO3 trigonal pyramid, AlO4, AlO5, and GaO4 polyhedra increased with increasing M2O3 content. Based on the local structures around Te, Al, and Ga atoms, the structure models of M2O3-TeO2 glasses were proposed.

DOI： 10.1111/j.1151-2916.2001.tb00749.x

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Language：English   Publisher：ELSEVIER SCIENCE SA  

Al-27 MAS NMR spectra of 12 fluoroaluminate crystals with known crystal structures and 40AlF(3). (20-x)BaF2. xBaCl(2). 20CaF(2). 17YF(3). 3EuF(3). glasses (x = 0, 3, 6, 9 and 12) in mol% were measured to examine the anion coordination environments around Al3+ in the glasses. All the glasses gave NMR spectra with very similar line profiles, indicating that the anion coordination environments around Al3+ are almost the same, and that only F- bonds to Al3+ regardless of the substitution of Cl for F. A comparison of the isotropic chemical shift values and the line profiles between glasses and fluoroaluminate crystals concludes that only AlF6 octahedra are present in the glasses and that these AlF6 octahedra mainly build up chains and/or rings by sharing the two corners in cis-configuration. Moreover, fairly sharp and symmetric line-profiles in the glasses suggest considerably high symmetry in the F--coordination around Al3+. (C) 2000 Elsevier Science S.A. All rights reserved.

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Language：English   Publisher：CHEMICAL SOC JAPAN  

Cd-113 magic-angle spinning (MAS) NMR spectra have been measured of twenty-three kinds of Cd2+-containing halide crystals with known structures to determine the isotropic chemical shifts delta(iso). The delta(iso) values of halogen coordination polyhedra largely changed with the kind and the coordination number of halogen. The relationship between the delta(iso) values and the halogen coordination environments around Cd2+ was revealed.

DOI： 10.1246/cl.2000.1046

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Language：English   Publisher：ELSEVIER SCIENCE BV  

In permanent densification of xSiO(2). 0.4(100 - x)K2O . 0.4(100 - x)CaO . 0.2(100 - x)SrO glasses (x = 41.2-66.7) in mol% by the 3 and 6 GPa high-pressure treatments a peculiar behavior was found in the glasses of x below 50 mol%. The skeleton structures composed of SiO4 units in the glasses were investigated on the undensified and densified glasses by means of Si-29 magic angle spinning (MAS) NMR spectroscopy. From the peak deconvolution of MAS NMR spectra the Q(n) fractions of SiO4 structural-units, where n (n = 0-4) means the number of bridging oxygen, were examined. At first, the skeleton structures in the undensified glasses are clarified. Then the skeleton structures of the densified glasses are discussed in comparison with those of the undensified glasses, Irrespective of the x value, the fractions of Q(n) of small n-values increased with an increase in the applied pressure, indicating that some of the Si-O-Si bonds are broken under the applied pressure and the skeleton structures were kept even after a release of the applied pressure. It is concluded that other causes should be considered as the origin of the present peculiar behavior, (C) 2000 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0022-3093(00)00090-9

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Language：English   Publisher：SOC GLASS TECHNOLOGY  

Structures of MO-TeO2 (M=Zn and Ba) glasses have been investigated by x-ray diffraction analysis. Local environments around Zn and Ba atoms weve examined in terms of the difference RDF curve, Delta RDF, which was obtained by subtracting the RDF curie of ZnO-Teo(2) glass from that of BaO-TeO2 glass at the same composition. Coordination numbers of Zn and Ba were estimated by the pair function curve fitting with the Delta RDF curves The coordination number of Zn atoms (NZn-O) decreased from 5.3 to 3.9 as ZnO content increased from 10 to 40 mol% Coordination numbers of Ba atoms (NBa-O) up to 35 mol% BaO were 6.1-6.4 independent of BaO content. N-BA (O) decreased over 35 mol% BaO and was 5.6 at 40 mol % BaO On the basis of the local structures around Zn and Ba atoms revealed in this work and the one around Te atoms derived from the previous (125) Te static NMR study: the detailed structure models of MO TeO2 (M=Zn and Ba) glasses were proposed.

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Language：English   Publisher：IOP PUBLISHING LTD  

The structures of V2O5-TeO2 glasses are investigated by means of Te-125 and V-51 static NMR spectroscopies and the local structures around the Te and V atoms are discussed in detail from the respective NMR spectra. The fraction of TeO3 trigonal pyramids increases and that of TeO4 trigonal bipyramids decreases with increasing V2O5 content. The structures of V2O5-TeO2 glasses are quite different from those of tellurite glasses containing network-modifying oxides. The fraction of VO4 tetrahedra increases and that of VO5 trigonal bipyramids decreases with increasing V2O5 content. Both chains consisting of tellurite structural units and those consisting of vanadate structural units contribute to the formation of the glass network in V2O5-TeO2 glasses.

DOI： 10.1088/0953-8984/12/12/302

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Language：English   Publisher：ELSEVIER SCIENCE BV  

The local structures of Sm and Al in Sm-doped aluminosilicate glasses prepared by the sol-gel method were investigated by using Al-27 MAS NMR spectroscopy and X-ray radial distribution function (RDF) analysis. It is found that at low alumina content (1 mol%). the glass network consists of SiO4 and AlO6 structural units. At higher alumina content, AlO4 and AlO6 structural units coexist in the glasses. It is considered that the formation of AlO4 results in enhancement of the dispersion of Sm ions in these glasses. The average coordination number of Sm in a 10Al(2)O(3). 90SiO(2). 1Sm(2)O(3) glass slightly increased from 7.1 to 8.5 after heat-treatment in reducing atmosphere. The role of Al ions in dispersing Sm ions in a glass matrix is discussed. (C) 2000 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0022-3093(99)00696-1

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Language：English   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

Cd-113 magic-angle spinning (MAS) NMR spectra of crystalline CdF2, KCdF3 and CdCl2 and vitreous 50CdF(2). 30NaF . 20BaF(2), 50CdF(2). 30NaCl .(20 - x)BaF2. xBaCl(2) (x = 0, 5, 10, 15 and 20) and 50CdCl(2). 15NaCl . 35BaCl(2) in mol% were measured so as to reveal the anion coordination environments around Cd2+ in the glasses. The CdF2, KCdF3 and CdCl2 crystals gave the isotropic chemical shifts of about -226, -105 and 183 ppm, which are assigned to the CdF8, CdF6 and CdCl6 polyhedra, respectively. The Cd-113 MAS NMR spectrum of 50CdF(2). 30NaF . 20BaF(2) glass enabled us to estimate quantitatively the fractions of CdF6, CdF7 and CdF8 polyhedra. The Cd-113 MAS NMR spectra revealed that the 50CdCl(2). 15NaCl . 35BaCl(2) glass consists of CdCl6 octahedra and that the 50CdF(2). 30NaCl .(20 - x)BaF2. xBaCl(2) glasses consist of CdF6-pClp, CdF7-qClq and CdF8 polyhedra (p = 0-6 and q = 0-5). The peak position and full-width-at-half-maximum values in the 50CdF(2). 30NaCl .(20 - x)BaF2. xBaCl(2) glasses increased as BaF2 was substituted for BaCl2. This implies that the substitution of BaCl2 for BaF2 results in an increase in the number of Cl- bonded to Cd2+ and the occurrence of various anion-coordination environments around Cd2+. (C) 2000 Elsevier Science Ltd. All rights reserved.

DOI： 10.1016/S0038-1098(00)00223-4

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Language：English   Publisher：ELSEVIER SCIENCE BV  

The structure of TeO2 and M2O-TeO2 (M = Li, Na, K, Rb and Cs) glasses has been investigated by means of Te-125 static and magic-angle spinning (MAS) NMR spectroscopies. On the basis of the relationship between the local structures around Te atoms and the NMR parameters obtained by Te-125 NMR spectra of various tellurite crystals, the local structures around Te atoms in TeO2 and M2O-TeO2 glasses were examined. The spectral simulation of static NMR spectra enabled us to discriminate between TeO3 trigonal pyramid (tp) and TeO4 trigonal bipyramid (tbp) and to estimate the fractions of TeO3 tp (N-3) and TeO4 tbp (N-4) It was concluded that in TeO2 glass TeO4 tbps are connected by sharing their corners as in alpha-TeO2 crystal. N-3 increased and NS decreased with increasing M2O content. On the basis of a previous structural model, the fractions of TeO4 tbp without a non-bridging oxygen (NBO) atom, TeO4 tbp with an NBO atom, and TeO3 tp with two NBO atoms were calculated. A new model which presents the structural change for M2O-TeO2 glasses has been proposed. (C) 1999 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0022-3093(98)00812-6

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Language：English   Publisher：ELSEVIER SCIENCE BV  

Te-125 static and magic-angle spinning (MAS) NMR spectra of tellurite crystals with known crystal structures have been measured to determine the isotropic chemical shift delta(iso), the chemical shift anisotropy Delta delta and the asymmetry parameter eta. On the basis of structural unit, tellurite crystals are classified for convenience into TeO3 type (isolated TeO3 and terminal TeO3 type), TeO3+1 type and TeO4 type (alpha-TeO2 and beta-TeO2 type). As a result, the following relations were found: TeO3 greater than or equal to TeO3+1 approximate to beta-TeO2 > alpha-TeO2 in delta(iso(MAS)), beta-TeO2 greater than or equal to alpha-TeO2 > TeO3+1 > terminal TeO3 greater than or equal to isolated TeO3 in \Delta delta\ and TeO4 greater than or equal to TeO3+1 greater than or equal to TeO3 in eta. It was also found that the combination of \Delta delta\ and eta, namely, the relative values of delta(1), delta(2) and delta(3), can elucidate the local structure around Te atoms more definitely than delta(iso). This diagram is useful for examining the structures of tellurite crystals and glasses. (Glasses are discussed in another paper.) (C) 1999 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0022-3093(98)00811-4

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Language：Japanese   Publisher：The Ceramic Society of Japan  

The structure of MO-TeO_2(M=Mg, Zn, Sr, Ba and Pb)glasses has been studied by means of ^<125>Te static NMR technique. The fraction of TeO_4 trigonal bipyramid(tbp), N_4 decreased and that of TeO_3 trigonal pyramid(tp), N_3 increased almost linearly up to 33.3 mol% MO and rapidly in the range of 33.3 to 40 mol% MO, with increasing MO content. It was found that the glasses containing Mo in the range of 40 to 45 mol% MO consisted only of TeO_3 tp. On the basis of the structural model proposed in a previous paper, the fractions of TeO_4 tbp without a non-bridging oxygen(NBO) atom, TeO_<4/2>(N_4^0> TeO_4 tbp with an NBO atom, O_<3/2> Te-O^-(N_4^-)and TeO_3 tp with two NBO atoms, O_<1/2>Te=(=O)-O^-(N_3^-)were calculated. The structural change for MO-TeO_2 glasses in the range of 0 to 33.3 mol% MO could be well represented by the model previously proposed for alkali tellurite binary glasses. A new model which represents the structural change for MO-TeO_2 glasses containing more than 33.3 mol% MO has been proposed.

DOI： 10.2109/jcersj.107.395

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