Tantalic acid lithium/the precise grinding constituent for the lithium niobate monocrystal material and uses that the tantalic acid lithium which/the precise grinding mannered null tantalic acid lithium monocrystal

摘要

PROBLEM TO BE SOLVED: To obtain a polishing composition which can polish the surface of a hard brittle material in high precision and can realize an excellent polishing efficiency and a long polishing life by dispersing in an aqueous medium α-alumina comprising microparticles having a specified or smaller mean particle diameter and a BET specific surface area in a specified range. ;SOLUTION: The α-alumina used comprises microparticles having a mean particle diameter (D50) of 0.3 μm or below, and a BET specific surface area of 15-50 m2/g. The α-alumina micropartieles used are desirably primary particles obtained by grinding a fired product made from boehmite and/or pseudo- boehmite and are desirably dispersed in an amount of 5-40 wt.%. It is desirable that the composition is adjusted to a pH of 8.5-12, and it is effective that silica particles are dispersed in the composition. The silica particles are desirably particles of colloidal silica, amorphous silicon dioxide, or fumed silica, and are dispersed in an amount of 45 wt.% or below, and it is desirable that the total amount of the α-alumina microparticles and the silica particles is at most 50 wt.%.;COPYRIGHT: (C)2000,JPO