Grain oriented ceramics and a production process thereof, a platelike powder for producing the grain oriented ceramics, and a thermoelectric conversion element

摘要

Grain oriented ceramics constituted of a polycrystalline body of a layered cobaltite in which a {001}plane of each grain constituting the polycrystalline body has an average orientation degree of 50% or more by the Lotgering's method. In this case, the layered cobaltite is preferably a layered calcium cobaltite expressed by the following general formula: {(Ca_1−xA_x)₂CoO₃+&agr;} (CoO₂+&bgr;)y (where A represents one or more elements selected among an alkali metal, an alkaline earth metal and Bi, 0 ≦×≦0.3, 0.5 ≦y ≦2.0, and 0.85 ≦{3+&agr;+(2+&bgr;)y}/(3+2y) ≦1.15). Such grain oriented ceramics are obtained by molding a mixture of the first powder constituted of a Co(OH)₂ platelike powder and the second powder constituted of CaCO₃ and the like such that a developed plane of the platelike powder is oriented, and by heating the green body at a predetermined temperature.