Low-temperature synthesis of superfine barium strontium titanate powder by the citrate method

Ba0.6Sr0.4TiO3 powder was synthesized by a citrate method. The phase development was examined with respect to calcining temperature and heating rate during the calcining process. The results reveal a crucial role of the heating rate to the formation of a pure perovskite phase at low calcining temperatures. It was found that keeping relatively low heating rates ≤0.7 °C/min during the calcining process after 300 °C was favorable to a sufficient decomposition of (Ba,Sr)2Ti2O5·CO3 intermediate phase at low temperatures and consequently led to the formation of a pure perovskite phase at 550 °C. Ba0.6Sr0.4TiO3 powder calcined at the temperature under the heating rate of 0.7 °C/min showed a superfine and uniform particle morphology and high sintering reactivity. As a result, the ceramic specimens prepared from the powder attained reasonable relative densities (94–95%) at sintering temperatures of 1250–1270 °C.