Method of manufacture of ceramic materials having a high dielectric constant, and ceramic materials thus obtained

摘要

1,186,116. Barium titanate ceramics. NIPPON TELEGRAPH & TELEPHONE PUBLIC CORP. 14 Dec., 1967 [19 Dec., 1966], No. 56781/67. Heading C1J. A barium titanate series ceramic of high dielectric constant is prepared by adding to the constituent raw materials of a barium titanate series semi-conductive ceramic 0À6 to 5À0 atomic per cent of an additional substance or substances comprising at least one compound containing one of the elements V, Cr, Mn, Fe, Co, Ni, Cu, As, Sb, Bi and TI or a mixture thereof, making into a shape, firing the shape in a gaseous atmosphere substantially free from oxidizing substance at a temperature of 1100‹ to 1500‹ C. and thereafter firing the shape in an oxidizing atmosphere containing a volume of oxygen the partial pressure of which is at least 1/100 th atmosphere at a temperature of 600‹ to 1150‹ C., said first-mentioned gaseous atmosphere being substantially replaced with said second-mentioned oxidizing atmosphere at a temperature of at least 600‹ C., whereby an insulating layer substantially consisting of a composition of said barium titanate series ceramic and ingredient elements of said additional substance or substances is formed along crystal grain boundaries throughout said ceramic, said grain size being at least 20 microns. The first atmosphere may be nitrogen, argon, neon, helium, hydrogen or carbon monoxide.