A magnesium phosphate glass having a molar ratio MgO/P₂O₅ of about one was prepared. Crystallization temperature of the glass was determined by DTA, which was carried out under various heating atmospheres and heating rates. Isothermal crystallization was examined by polarizing and electron microscopy using a plate-form specimen.
In all cases crystallization of magnesium metaphosphate (magnesium tetrametaphosphate) started from the surface of the specimens. This crystallization was found to consist of the following three processes (I), (II) and (III). (I) Polycrystals with radial form grew occasionally at the surface of the glass specimen below about 620°C. (II) Many fine granular crystals with particle size of 1 μ to 6 μ formed at the whole surface of the specimen above about 620°C. (III) At still higher temperatures the growth of the polycrystals occurred from the surface into the inside of the specimen.
The crystal growth rate in Process (II) at 640°C and the activation energy for the growth were determined to be 1×10^-2μ/min and 110kcal/mol, respectively. White dense products and porous materials were produced in Processes (I) and (III), respectively.
The changes in the crystallization and transformation temperatures with the heating atmosphere were discussed on the basis of water in glass structure, in which isolation of the water was related to condensation of the phosphate anions.

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Some of PbO-TiO₂-SiO₂ glasses are converted into polycrystalline materials consisting mainly of perovskite-type PbTiO₃ crystals by heat treatment. However, the kind of crystals first precipitated in the glasses on heating was found to be markedly affected by the amount of Al₂O₃ in the glasses. For its reasoning, the crystallization processes of the PbO 40, TiO₂ 25, SiO₂ 35mol% glass (glass 1) and PbO 40, TiO₂ 25, Al₂O₃ 10, SiO₂ 25mol% glass (glass 2) were investigated by means of DTA, electrical resistivity measurement, X-ray diffraction analysis, electron microscopic observation, infrared spectroscopic analysis and fluorescent X-ray spectroscopic analysis. The results are summarized as follows:
1) It is concluded that glass 1 as-annealed has a homogeneous structure being composed of a network of uniformly distributed SiO₄, TiO₄ and PbO₄ tetrahedra and modifier ions of Ti⁴⁺ and Pb²⁺ sitting in holes of the network. On heat treatment, the glass crystallizes directly forming a metastable pyrochlore-type lead titanate dissolving a small amount of SiO₂, without going through any precursory structural change such as glassy two-phase separation. At an elevated temperature, the pyrochlore-type crystals transform to the perovskite-type PbTiO₃ crystals.
Glass 2 as-annealed has a two-phase structure being composed of a large number of minute glassy droplets rich in PbO and TiO₂ and a continuous glassy matrix rich in SiO₂. On heat treatment, the droplets first grow in size at the expence of the matrix, so rapidly as a sharp exotherm peak can be observed in DTA, and then the perovskite-type PbTiO₃ crystals precipitate in the droplets.
2) It is concluded that addition of the Al₂O₃ to a PbO-TiO₂-SiO₂ glass induces a glassy two-phase separation, and as the result promotes precipitation of the perovskite-type PbTiO₃ crystals in the PbO- and TiO₂-rich phase, thus suppressing formation of the metastable crystal. The effect of the Al₂O₃ on the glassy two-phase separation is interpreted in terms of “tricluster” model proposed by Lacy and field strengths of the constituents ions.

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Redox equilibria of glass melts with oxygen and CO₂-CO mixtures containing oxygen partial pressures from 10⁰ to 10^-14 atm were studied. The structure-sensitive properties of quenched glasses such as specific resistivity, were found to be correlated to the redox equilibrium.
In the glass melts of 5Fe₂O₃⋅95RP₂O₆ and 7TiO₂⋅93RP₂O₆, the concentration ratios [Fe²⁺]/[Fe³⁺] and [Ti³⁺]/[Ti⁴⁺] were the highest for the lowest basicity (R=Mg), decreasing in the order of Mg, Ca, Ba (O-type), while concentrations of high-valent ions (Fe³⁺, Ti⁴⁺) remained nearly unchanged and those of low-valent ions (Fe²⁺, Ti³⁺) decreased.
On the other hand, in the glass melts containing larger amounts of Fe₂O₃ such as 20Fe₂O₃⋅80RP₂O₆, the ratio [Fe²⁺]/[Fe³⁺] increased with increasing basicity (R-type). At high oxygen partial pressures, ferric ion concentration remained nearly unchanged and ferrous ion increased with increasing basicity. At low oxygen partial pressures ferrics ion decreased and ferrous ion concentration remained nearly unchanged.
The specific resistivities of the quenched glasses of 7TiO₂⋅93RP₂O₆ and 20Fe₂O₃⋅80RP₂O₆, which were obtained from the melts in redox equilibria, decreased with increasing basicity by replacing R with Mg, Ca, Ba. A minimum of specific resistivity was observed when the concentration ratio of low to high valent ions of transition metal was approximately equal to unity. However, this ratio decreased for the glasses of 7TiO₂⋅93RP₂O₆ and increased slightly for 20Fe₂O₃⋅80RP₂O₆ as the basicity increased. TiO₂ was more effective than Fe₂O₃ on the lowering of specific resistivity.
It is concluded from these experimental results that the redox equilibria in the melts of 5Fe₂O₃⋅95RP₂O₆ and 7TiO₂⋅93RP₂O₆ are expressed as,
2[XO_x]^(2x-n-m)-=2Xⁿ⁺+(2x-m)O^2-+m/2 O₂
where X is Fe or Ti and m=1. Complex oxiacid ions Fe₂O₅^4- or TiO₄^4- seemed to be involved in the equilibria.
In the melts of 20Fe₂O₃⋅80RP₂O₆, equilibrium is expressed as,
2[XO_x]^(2x-n-m)-+(m-2(x-y))O^2-=2[XO_y]^(2y-n)-+m/2 O₂
The oxygen ion coordination number of the ferrous complex ion has not been found in the present work.

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Inhomogeneous structure was found in As-S-Te-I glasses and the relation of the inhomogeneity and electrical resistance was investigated. The appearance of the inhomogeneous structure was dependent on the glass composition, particularly on the atomic ratio of sulfur to arsenic: the spherical dispersion phase was observed in the glasses with the ratio of about 1.5, the spherical and worm-like dispersion phases with the ratio of 3.5, and the spheroidal and randomly deformed-spheroidal dispersion phases with the ratio of 0.5. Current-voltage characteristcs were measured by using a pair of point contact electrodes for the spherical dispersion phase and for the continuous phase of the glasses with the ratio of 1.5. In the former phase, the characteristics were composed of three regions; ohmic, exponential and negative resistance ones; the switching in this phase occurred at an electric field of about 10³V/cm; these characteristics were explained in terms of Joule heating. In the latter phase, switching occurred at an electric field as high as 10⁵V/cm, and varistor-like current-voltage characteristics were observed in the memory state. In addition to these features, there was a great difference of 6-8 orders of magnitude in resistivities between the dispersion and continuous phases for a given glass. When the glass composition varied, the resistivity ranged from about 10² to 10⁶ ohm·cm for the spherical dispersion phase and from about 10⁸ to 10¹⁴ ohm·cm for the continuous phase. The constitution of these phase. The constitution of these phases was discussed on the basis of the above results.

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The elastic constants and their temperature derivatives for As-Se glasses have been determined by means of ultrasonic interferometry technique. The data obtained for wave velocities, bulk modules, shear modulus, Young's modulus, Poisson's ratio, their temperature derivatives, Debye temperature and Grüneisen parameters are listed in Table 2. The data of variation of the elastic constants with composition in the system As-Se are shown in Fig. 2-6, Fig. 10 and Fig. 12.
The results are summarized as follows:
1) The values of isotropic wave velocities υ_p and υ_s at room temperature are υ_p=1.8km/sec and υ_s=0.92km/sec for Se glass, υ_p=2.2km/sec and υ_s=1.2km/sec for As₂Se₃ glass. It is found that the value for As-Se glass is lower than that for oxide glasses.
2) The elastic constants increase with increasing the As content up to its maximum at about 40 atomic percent As and then decrease. The maximum in the curve seems to be interpreted as evidence of structural grouping tn the glass corresponding to the compound As₂Se₃.
3) The bulk modulus-volume relationship shown in Fig. 8 reveals that the bulk modulus varies approximately as the inverse fourth power of volume.
4) Temperature derivative of the isotropic longitudinal wave velocity is negative for As-Se glass and B₂O₃ glass whereas it is positive for other oxide glasses, that is, SiO₂, GeO₂ glasses.
5) The Debye temperature θ_D determined from equation (8) is θ_D=103°K for Se glass and θ_D=130°K for As₂Se₃ glass. The Grüneisen parameter δ_s calculated from the measured thermal data is estimated to be 5-8.

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Magnetic susceptibility, density and lattice constant of V₂O_3+x fired at 1600°K and 1700°K were measured.
When x (in V₂O_3+x) reaches to 0.03, a discontinuity was found in the curve of susceptibility vs. nonstoichiometric parameter x. The similar discontinuity was also found in the density curve at x≅0.04. At x≅0.05 an abrupt change in the lattice constant was detected.
Magnetic susceptibility measurement seems to be the most sensitive method for detecting nonstoichiometry in the V₂O_3+x compound.

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The negative surface charges of some kaolinites from different origins were determined, paying attention to the distribution of the charges on basal and edge surfaces. The relations between the charge density and the particle morphology or crystallinity were considered.
The negative charges on the basal and edge surfaces were assessed from the C. E. C. values at pH 4 and from the difference in the C. E. C. values at pH 10 and pH 4, respectively. The crystallinity was evaluated from the ratio of the two peak intensities (I₍₀₂₁₎/(I₍₀₆₀₎) of X-ray diffraction. The particle shape was observed electron microscopically.
The results obtained are summarized as follows;
1) The kaolinites of nine species studied could be classified into two groups by the magnitude of the negative charge density.
2) Four kaolinites which showed high negative charge densities were poorly stacked to the direction of c-axis. The particles were rather thin shape owing presumably to high degree of isomorphous substitution. The negative charge densities on the basal surfaces, particularly in fine particles, were larger than those on edge surfaces.
3) The remaining five kaolinites having low negative chargede nsities were well stacked and the particles were rather thick. The negative charge densities on the basal surfaces were almost same as those on edge-faces.

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The vaporizations of MgO from single crystals of two kinds of spinel, MgO⋅0.9 Al₂O₃ and MgO⋅2.8 Al₂O₃, were studied in vacuum at 1700°-1950°C. At an initial stage the vaporization rate was constant and it was controlled by a decomposition reaction of the spinel. At a later stage of the vaporization the rate showed an one-dimensional diffusion controlled one. MgO vaporized through the corundum layer formed on the spinel where the diffusion of oxygen ion might be rate-determined. This corundum was formed by the vaporization of MgO above 1800°C from the spinel and by the vaporization plus an exsolution from the solid solution limit of the spinel below 1800°C.

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