YUAN Qi, LIU Gaobin, HAN Lu, WANG Sen

(Liaoning University of Science and Technology, School of Materials and Metallurgy Engineering,
Anshan, 114051, Liaoning, China)

Abstract: Ultra-fine well dispersed doped barium zirconium titanate powder was synthesized by means of hydrolysis-precipitation method in this work. The effect of Nb⁵⁺ and Ca²⁺ on structure and dielectric properties of the barium titanate ceramics sintered in reducing atmosphere was studied. It is found that crystal phase of the doped sample has a tetragonal phase. The presence of Ca²⁺ accelerates the formation of a small quantity of hexagonal BaTiO_3-x after sintered in the reducing atmosphere, which depleted oxygen vacancies in the sample and made it to have a high resistance after sintering. The donor doping of Nb^{5 +} for Ti⁴⁺ and Ca²⁺ work together to form a small amount of liquid phase in the sample during sintering at high temperatures. At the fixed Ca²⁺ concentration of 3 mol%, the contents of Nb⁵⁺ were 0, 0.1, 0.2, 0.4 mol%. With increasing content of Nb⁵⁺, the relative density was increased and the grain growth was promoted, which in turn resulted in a decrease in dielectric loss. The ε-t curves of the Nb⁵⁺ doped samples are more flat, making them suitable for temperature stable type capacitor applications.
Key words: zirconia barium titanate; dielectric loss; ε-t curve