Interactions between multivalent ions in lasses or between the multivalent ions and Ag⁺ and Cu⁺ ions, which diffused into the glasses from a molten salt, and the formation of metallic colloids were investigated by optical and paramagnetic resonance absorption spectra. It was confirmed by chemical analyses and near-infrared absorption spectra that the redox reaction of pentavalent arsenic or antimony ions with ferrous ions took place. The formation of nAg⁰ mCu⁰ colloids in the lasses was confirmed by optical absorption spectra. Ag⁰ signals of the stained glasses were detected at room temperature only after γ-ray irradiation. No optical absorption caused by Cu₂O colloids and paramagnetic resonance signals by Cu⁰ were found. The ability to reduce Ag⁺ and Cu⁺ ions into metallic colloids was in the order of FeO<As₂O₃<Sb₂O₃. It was presumed that colloidal silver particles were mainly in the forms of nAg⁰(n>1) and Ag⁺ ions.

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Co-ordination of Al-ions and the bond length of Al-O in high alumina glass were determined by the radial distribution function analysis using X-ray diffraction technique. A silica glass, two kind of Al₂O₃-SiO₂-Na₂O glasses and an Al₂O₃-SiO₂-MgO glass were employed for the analysis.
The radial distribution function of these test pieces were computed with the diffracted intensities which were counted with fixed time method by scintillation detector plus pulseheight analyzer applying filtered Cu and Mo radiations. The bond length between the atoms were estimated from radial distribution curves and the results obtained were as follows:
Si-O 1.60Å Si-Si 3.15Å
Al-O 1.73Å Al-Al 3.30Å
Mg-O 1.93Å
The co-ordination numbers of Al-ions evaluated from radial distribution function analysis as follows:
These corresponded to 5.1-fold when the ratio of Al₂O₃/Na₂O in the glass was 1.63, and 4.6-fold when the ratio was 0.87.
These values were agreed well with the values obtained from the X-ray fluorecence study.

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To elucidate the relation between the redox equilibrium of transition metals and acidbase properties in molten oxysalts, the variation of V (IV)-V (V) equilibria with the composition of melts was investigated on V₂O₅-M₂O and V₂O₅-MPO₃ systems (M: alkali metal). The structure of quenched sample was examined by means of X-ray diffraction, IR spectroscopy and paper chromatography. The summary of results is as follows:
(1) In molten V₂O₅-M₂O, percent reduction of vanadium, V(IV)×100/[V(IV)+V(V)] decreases with increasing basicity and becoms nearly zero at the composition of meta vanadate (Fig. 3). Bronze-like structure, V(IV)-O-V(V) network, is also found to be less stable for oxidation in molten state than in the solid one.
(2) In molten V₂O₅-KPO₃, KPO₃ is more acidic than V₂O₅ and acid-base reactions represented by eqs. (8)-(14) are in equilibrium between both components. Equilibrium ratio of V(IV)/V(V) increases with increasing KPO₃ content, that is, decreasig the basicity of the melt, up to 90mol%, and decreases again at 99mol% (Figs. 5 and 6). Paper chromatographic analysis of phosphate ions suggests that, when KPO₃ content is higher than 70mol%, vanadium component exists in the forms of VO₂⁺, VO³⁺ and VO²⁺. In this range of high concentration of KPO₃, the dependence of redox equilibrium of vanadium on the concentration of free oxygen ions can be explained with the following equations,
VO₂⁺_??_VO²⁺+1/2O^2-+1/4O₂…(a)
VO³⁺+1/2O^2-_??_VO²⁺+1/4O₂…(b)
V(IV)/V(V)=K_aPo₂^-1/4/{(O^2-)^1/2+K_a/K_b(O^2-)^-1/2}…(c)
(3) The shift of redox equilibrium of vanadium towards the more oxidized state in K-salt than in Na-salt, Fig. 7, means that K⁺ ions keep the melt more basic than Na ions do. This difference may result from the difference in the polarizing power between Na⁺ and K⁺ ions.
(4) The ion fraction of free oxygen ions calculated by applying Masson's approach to silicate melts does not agree with one estimated from eq. (c) (Figs. 13 and 14). This suggests that the effects of cation on the basicity of melt must be taken account as well as the anionic distributions.

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Fluor-richterite (Na⋅NaCa⋅Mg₅⋅Si₈:O₂₂F₂) composition glass was subjected to the heat treatments for glassy phase separation, nucleation and crystal growth and the phase separation and the crystallization were studied by the electron microscopy and X-ray powder diffraction method. The effect of glassy phase separation on the nucleation was discussed. The results obtained were as follows:
1) As previously reported by the author, droplets were formed by the glassy phase separation in the sample after heating at the temperature of glassy phase separation treatment in the range from 550 to 650°C. The number and the grain size of the droplets varied with the temperature and the time of heat treatment.
2) Crystallization was observed in the sample after heating at the temperature above 600°C. At lower temperatures in the crystallization temperature range, the crystallization appeared to start from the surface of droplets that had formed before the crystallization. A layer structure crystal such as fluor-mica or fluor-talc crystallized in preference to fluor-richterite.
3) At the temperature of nucleation treatment of 725°C, most of the droplets disappeared rapidly, the layer structure crystal decomposed slowly and the fluor-richterite crystallized.
4) The sample heated at 600°C or 625°C for a long time contained a larger number of droplets and a small amount of crystalline phase and was converted to a translucent glass-ceramics by the heat treatments for nucleation and crystal growth. The translucent glass-ceramics was characterized by the smallest size and the largest number of fluor-richterite microcrystals and a small amount of residual glass.
5) It was considered that the nucleation sites were given on the droplet surfaces by the reaction between the droplet surface having a three-dimensional random network structure and the cation or the silicate anion present in the matrix glass phase and that the number of nucleation sites varied with the temperature and the time of the heat treatment for glassy phase separation. The layer structure crystal and fluor-richterite were nucleated on these sites and fluor-richterite was nucleated on the surface of the layer structure crystal.

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