Glass-forming abilities of melts in the systems (R₂O or R′O)-Bi₂O₃-Al₂O₃, where R is Na or and R′ is Sr, Ba, Zn, Cd or Pb, were examined with ordinary crucible-melting technique; melting 20g of raw materials in a sintered alumina crucible (Al₂O₃>99.5wt%, SiO₂ <0.1wt%), pouring the melts onto a steel plate and pressing them into plates about 2mm thick. Clear glasses were obtained from some of the melts in the systems (CdO or PbO)-Bi₂O₃-Al₂O₃. X-ray emission spectra of the glasses showed that the Al³⁺ ions in the glasses are tetrahedrally coordinated with oxygen ions. From the location of the glass-forming region in the systems, the structures of the glasses were estimated to have AlO₄, BiO₄ and CdO₄ (or PbO₄) polyhedra, as network formers and Cd²⁺ (or Pb²⁺) and Pi³⁺ ions as modifiers. The glasses 1mm thick showed high transmissions of visible and infrared radiations ranging from 0.5 to 6μm. The high transmission in the infrared region were ascribed to the absence of low mass ions which tend to form strong bond with oxygen ions, such as Si⁴⁺ ions, in these glasses.

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A new fabrication method of the wollastonite ceramics which can be used as low dielectric loss insulation in high-frequency application was developed and effect of the additives on the dielectric properties was discussed.
The wollastonite ceramics are difficult to fabricate by the normal ceramic processes which the wollastonite-clay mixtures are used as the starting materials, because the dense bodies are obtained only in the limited region of maturing temperatures.
In order to overcome this fabricating difficulties, a new producing process was developed. The raw materials having wollastonite composition were melted at higher temperature than those melting point, and were quenched into ice-water. The obtained glassy masses were crushed and cold-pressed. When the glass powder compacts were fired at fairly low temperature as 900°C or 1100°C, those were compacted to pore-free state by the viscous flow mechanism and the wollastonite (β-CaO⋅SiO₂) crystallized in the compacted bodies simultaneously.
By the new process, the dense polycrystalline wollastonite ceramics were produced over a wide temperature range (about 200°C).
The obtained bodies have extremely low dielectric loss factors of the order of Grade L-6 and have a high corrosion resistance against HCl solution.
The effects of additives by which the dielectric property of matrix (glass) phase in the ceramic insulator might be improved, did not show unexpectedly in the present work, because those crystallized with other component (for example, CaO, SiO₂, Al₂O₃) in the wollastonite grain boundaries.
The ceramic bodies consisting of the pseudo-wollastonite (α-CaO⋅SiO₂) crystallized in the tested specimens as the primary phase showed a low loss characteristics similar to the bodies consisting of the wollastonite.

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Coloration of aluminosilicate glasses in the system La₂O₃-Y₂O₃-Al₂O₃-SiO₂ doped with various transition metal oxides (NiO, Fe₂O₃, MnO₂, CuO, Co₃O₄, Cr₂O₃ and V₂O₅) have been studied. The colors of 11.15La₂O₃ 11.15Y₂O₃⋅22.7Al₂O₃⋅55.0SiO₂ (in mol%) glass containing the transition metal elements were found to be nearly similar to those of sodalime glass except for coloring agents MnO₂ and CuO. The changes of color have been investigated by replacing Y₂O₃ by other oxides with different single bond strength, that is, Na₂O, K₂O, CaO, PbO and B₂O₃. The absorption bands of Cr³⁺ and Mn³⁺ shifted to higher wavenumber as the single bond strength of the replacing oxides became smaller.

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This study is concerning the effect of additives on sintering of magnesia. The seven different compounds with the same cation, calcium ion, were selected as the additives. These additives were mixed with magnesium hydroxide, and calcined at 900°C. The resultant specimens were fired at 1500°or 1600°C and their sinterability and microstructure were examined.
Calcium hydroxide, carbonate and oxalate which decomposed to lime during calcination, had little effects on periclase crystal during the calcination, but at the latter stage of sintering, the lime retarded the growth of periclase grains and prevented pores to be engulfed into the periclase grains, and consequently promoted densification of the magnesia.
Calcium nitrate which melted during calcination promoted comparatively well the crystallite growth of periclase and improved compactness of the calcined material and enhanced its densification markedly at the latter stage.
Calcium chloride and sulfate which also melted during calcination or initial stage of the firing promoted the grain growth of periclase and delayed the sintering of magnesia at the initial stage, but at the latter stage the grain growth was suppressed by their moderate grain size and the presence of lime, and finally their densification was promoted.
Calcium fluoride, accompanied with its decomposition during firing, promoted remarkably the early stage sintering of the magnesia.
Thus each calcium compound, all of which, after the firing, changed to the same oxide, lime, gave markedly different effects on the calcination and sintering of magnesia and finally promoted the sintering of magnesia.
The optimum amount of additives for the sintering was about 2wt% as CaO, which was slightly larger than the solubility limit into periclase at temperature of 1500°C to 1600°C.

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This report describes on formation of crystallized foam glass and its bloating mechanism using a volcanic ash “Shirasu” as main raw material, Na₂O, Li₂O, TiO₂, ZrO₂, Fe₂O₃ as additive components, and carbon as bloating agents. The mixtures were melted to obtain glass cullet. The glass cullet was ball-milled to pass through a sieve of 420μm in diameter. The ground cullet was press-moulded at 15kg/cm² to a compact of 4×4×4cm.
The heat treatment of compacts were heating up to 760°C at a rate of 160°C/h-1100°C/h and kept at 760°C for 10min.
The results obtained are summarized as follows:
(1) Ground Gullet glass compact with an adequate crystallizing property showed smaller deformation by softening during heat treatment due to the elevation of softening temperature followed with the crystallization of Li₂O⋅SiO₂ and an unknown crystal than that without crystallizing property.
(2) Thermal expansion coefficient decreased through crystallization.
(3) The specific compressive strength (compressive strength/apparent specific gravity) of partially crystallized foam glass was larger remarkably compared with that of non-crystallized one.
(4) Generated foaming gases during heat treatment of compacts were oxygen through reduction of Fe₂O₃, adsorbed gas for carbon, decomposed gas from a few organic material contained and dissolved gas in glass cullete.

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