Abstract: The invention provides a lithium manganese oxide spinel suited as a cathode active material for lithium ion secondary batteries showing excellent high-temperature cycling behavior. The lithium manganese oxide is represented by the following general formula (1): Li1+&agr;Mn2−&agr;−yMyO4−&dgr; wherein O≦&agr;≦0.5, 0.005≦y≦0.5, −0.1≦&dgr;÷0.1, and M represents a metal element other than Li and Mn, and which shows the ratio of a main peak intensity at 5±40 ppm to a main peak intensity at 525+40 ppm (I0ppm/I500ppm), each intensity being obtained by 7Li-NMR measurement according to the following measuring method, falling within the following range: I0ppm/I500ppm≦0.65y+0.02.

Abstract: The invention provides a lithium manganese oxide spinel suited as a cathode active material for lithium ion secondary batteries showing excellent high-temperature cycling behavior.

Abstract: A synthetic quartz powder obtained by calcining a powder of silica gel, characterized in that white devitrification spots having sizes of larger than 20 &mgr;m in diameter formed in an ingot obtained by vacuum melting the synthetic quartz powder at a temperature of from 1780 to 1800° C. to form an ingot, followed by maintaining the ingot at a temperature of 1630° C. for 5 hours, are at most 10 spots/50 g.

Abstract: A method for producing a high purity synthetic quartz powder, characterized by using a tetramethoxysilane having a trimethoxymethylsilane content of at most 0.3 wt %, and converting it to a synthetic quartz by a sol-gel method.

Abstract: A process for producing synthetic quartz powder which comprises calcining silica gel powder to produce a synthetic quartz glass powder, wherein dry air is used in the calcining process at least in the process of cooling from 800.degree. C. to 200.degree. C. This process enables efficient production of synthetic quartz glass powder on an industrial scale.

Abstract: A synthetic quartz glass powder obtained by sol-gel method, wherein the number of black spot particles is at most 5 particles per 50 g, provides a high quality quartz glass shaped product with low bubble content when fused.

Abstract: A spiro-naphtho-oxaine compound having a specific substituent providing red color development which has been unknown in the past, and photosensitive materials containing the compound. Since the compound is superior in fatigue resistance and has a sufficient red color developing density, it is used in plastic articles, optical filters, recording materials, textiles, decoration materials, and toys, which change in color by light irradiation to develop a magenta color.

Abstract: A synthetic silica glass powder obtained by calcining a silica gel powder obtained by hydrolysis of a tetraalkoxysilane, said synthetic silica glass powder containing from 1.times.10.sup.-1 to 1.times.10.sup.-4 ppm of boron and having an internal silanol group concentration of at most 150 ppm and an isolated silanol group concentration of at most 5 ppm.

Abstract: Synthetic quartz glass powder is produced by (a) hydrolyzing an alkoxysilane to form a gel, (b) finely dividing the gel and then drying, or drying the gel and then finely dividing, and (c) calcining the obtained powder, the powder being maintained under an atmosphere with an oxygen concentration of not less than 30 vol % during at least a part of the calcining period at a temperature of not lower than 1,000.degree. C.

Abstract: A silica glass powder suitable for the production of a silica glass body product of a low silanol content, which is obtained by baking a dried silica gel powder obtained by a sol-gel method, at a temperature of from 1,000.degree. to 1,400.degree. C., wherein during the baking period, the silica gel powder is baked in a gas atmosphere containing from 10 to 100% by volume of steam for at least 5 hours.

Abstract: A process for producing a ceramic preform, which comprises mixing an alkoxysilane and fine silica powder, molding the mixture, followed by heating for de-alcoholysis.

Abstract: A process for the production of highly concentrated phosphoric acid, comprises improvements in digesting phosphate rock with a mixed acid consisting essentially of sulfuric acid and phosphoric acid to obtain a slurry comprising phosphoric acid and hemihydrate (CaSO.sub.4.1/2H.sub.2 O), then filtering the slurry, taking out highly concentrated phosphoric acid as product acid and subsequently hydrating the hemihydrate to obtain gypsum (dihydrate: CaSO.sub.4.2H.sub.2 O).