Effect of dopants on synthesis of BaTi4O9 and Ba2Ti9O20 ceramics prepared by reaction-sintering process

The effect of dopants on BaTi4O9 (BT4) and Ba2Ti9O20 (B2T9) ceramics by the reaction-sintering process was investigated. CuO addition is more effective in lowering the sintering temperature of BT4 and B2T9 ceramics. MnO2 and CuO addition are effective to obtain temperature stable BT4 ceramics. With MnO2 addition, Q × f of BT4 ceramics could be raised. ZrO2 addition is effective to obtain B2T9 ceramics with higher dielectric constant. With CuO addition, τf of B2T9 ceramics shifted toward negative values and 0 ppm/°C could be obtained. Optimum properties in BT4 doped with MnO2 of ɛr = 37.1, Q × f = 51,200 GHz (at 7 GHz) and τf = 0 ppm/°C and in B2T9 doped with ZrO2 of ɛr = 37.9, Q × f = 39,700 GHz (at 7 GHz) and τf = 5.9 ppm/°C were obtained.