Dense fine grained ceramics of barium titanate

Abstract

A sintering optimization of barium titanate ceramics from fine grained and homogeneous reproducible powders obtained by the citric process is presented. Different sintering parameters are studied: heating rates, final temperature, dwelling times at this final temperature, influence of the powder deagglomeration step. The ceramics obtained by sintering at 1230 or 1300°C are barium carbonate free, the residual carbon content being estimated at about 400 ppm in the surface layer. They exhibit a grain size close to 1 μm, a structure in which the cubic and tetragonal phases coexist, and a density of about 96% of the theoretical density. Their permittivity and loss factor are respectively about 5000 and 2.5 × 10⁻² at 25°C. Dielectric properties have been investigated in BaTiO₃ ceramics sintered at 1300°C in varying sintering atmospheres (O₂ and N₂).