| 摘要 |
PURPOSE:To inexpensively manufacture the titled parts having a prescribed refractive index distribution by reacting a silicic acid soln. with an org. compound to form each porous gelled article, impregnating the article with CaNO3, etc. after perfect elution, and carrying out suitable elution. CONSTITUTION:A silicate soln. of 10-15pH contg. about 1-12mol/l SiO2 is prepared using ordinary silicate. This soln. is mixed with an org. compound causing Cannizzaro's reaction, and they are reacted at the freezing point of the soln. - the b.p. to form each porous gelled article of cohered silica. The article is subjected to elution up to the central part with water, an aqueous weak acid soln. or an aqueous org. substance soln. The article after the elution is stuffed by dipping in a soln. prepared by dissolving one or more among CsNO3, RbNO3, TlNO3, etc., and elution is carried out from the outside under suitable conditions to obtain a prescribed concn. distribution in the micropores. The article is optionally dipped in an org. solvent to deposit CsNO3, etc., and after decomposing the compounds by vacuum drying, the article is calcined at below the m.p. of the silica. |
