Dense Ceramics of BaTiO_3 Produced from Powders Prepared by a Chemical Process

摘要

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, and influence of the powder deagglom-eration step. The sintering is followed by dilatomet-ric measurements. The ceramics obtained by sintering at 1230 or 1300℃ are free of barium carbonate, 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 x 10~(-2) at 25℃.