Abstract: It is an object to provide fine particles of bismuth titanate having excellent dielectric characteristics, high crystallinity and a small particle diameter, and a process for their production. The object is accomplished by a process which comprises a step of obtaining a melt comprising, as represented by mol % based on oxides, from 23 to 72% of Bi2O3, from 4 to 64% of TiO2 and from 6 to 50% of B2O3, a step of quickly quenching this melt to obtain an amorphous material, a step of crystallization of bismuth titanate crystals from the above amorphous material, and a step of separating the bismuth titanate crystals from the obtained crystallized material, in this order.

Abstract: To provide a composition for forming a dielectric layer excellent in dielectric constant and withstand voltage properties, a MIM capacitor and a process for its production. A composition for forming a dielectric layer, which comprises fine particles of perovskite type dielectric crystal, glass frit, and a hydrolysable silicon compound or its oligomer, and a MIM capacitor comprising a substrate, and a bottom electrode layer, a dielectric layer having a structure such that fine particles of perovskite type dielectric crystal are dispersed in a silicon oxide matrix containing glass-forming ions and a top electrode, formed on the substrate in this order.

Abstract: A process for preparing a silicate porous product, which comprises a step of forming a clay mineral into a dispersion by means of a dispersant, a step of removing gases dissolved in the dispersion, a step of freezing the dispersion and drying it in its frozen state under reduced pressure, and a step of firing the dried product obtained by the drying.

Abstract: A process for preparing a silicate porous product, which comprises a step of forming a clay mineral into a dispersion by means of a dispersant, a step of removing gases dissolved in the dispersion, a step of freezing the dispersion and drying it in its frozen state under reduced pressure, and a step of firing the dried product obtained by the drying.

Abstract: A fused-cast-alumina-zirconia-silica refractory consisting essentially of corundum crystals, baddeleyite crystals and a matrix glass phase and having a chemical composition comprising (a) from 30 to 70 wt % of Al.sub.2 O.sub.3, (b) from 20 to 59 wt % of ZrO.sub.2, (c) from 5 to 12 wt % of SiO.sub.2, (d) from 0.15 to 0.60 wt % of Na.sub.2 O, (e) from 0 to 0.50 wt % of K.sub.2 O, (f) from 0 to 0.40 wt % of Li.sub.2 O, (g) from 0.05 to 0.80 wt % of B.sub.2 O.sub.3, (h) from 0.05 to 0.80 wt % of P.sub.2 O.sub.5, and (i) from 0.05 to 0.50 wt % in total of at least one member selected from the group consisting of SnO.sub.2, ZnO, CuO and MnO.sub.2.

Abstract: High zirconia fused cast refractories which include as chemical components of refractories in weight %, 85 through 91% of ZrO.sub.2, 7.0 through 11.2% of SiO.sub.2, 0.85 through 3.0% of Al.sub.2 O.sub.3, 0.05 through 1.0% of P.sub.2 O.sub.5, 0.05 through 1.0% of B.sub.2 O.sub.3 and 0.01 through 0.12% of a summed amount of K.sub.2 O and Na.sub.2 O, wherein the weight % of K.sub.2 O is not smaller than the weight % of Na.sub.2 O.