| 摘要 |
PURPOSE:To inexpensively manufacture the titled parts having a prescribed refractive index distribution by mixing a silicic acid soln. contg. >=1 kinds of silicate selected from Tl, Cs and Rb silicates with an org. compound, converting the mixture into each porous gelled article, and carrying out leaching. CONSTITUTION:A soln. of 10-15pH contg. >=1 kinds of silicate selected from Tl, Cs and Rb silicates by 1-12mol/l as SiO2 or further contg. other silicate is prepared. This soln. is mixed with an org. compound such as (HCHO)n, methyl formate or ethyl acetate and reacted at the freezing point of the soln. - the b.p., thereby cohering SiO2 and causing gelling to porous silica. The porous silica is immersed in a mixed soln. consisting of water, alcohol, ketone and weak acid to remove excess alkali silicate, etc. by leaching. At this time, Tl<+>, etc. are also eluted, so by stopping the leaching, concn. gradients of Tl<+>, etc. are formed. The resulting silica is optionally dipped in an org. solvent, vacuum-dried, and calcined at below the m.p. of the silica to burn the org. matter by oxidation. |
