Influence of Zr/Ti ratio on the dielectric properties of BaZr_xTi_(1-x)O_3 ceramics for high-voltage capacitor applications

摘要

Ba(Zr_xTi_(1-x))O_3 ceramics are prepared via the conventional solid state reaction method. The Zr~(4+) ions have diffused into the BaTiO_3 lattices to form a homogenous solid solution. The effects of Zr/Ti ratio on dielectric properties and breakdown strength of Ba(Zr_xTi_(1-x))O_3 ceramics are systematically discussed. The high porosities of Ba(Zr_xTi_(1-x))O_3 ceramics deteriorate seriously the dielectric constant, dielectric loss and the breakdown strength. When the concentration of Zr~(4+) ions increase from x = 0.05 to x = 0.20, the Curie temperature T_c decreases slightly from 120 to 60 ℃, the grain sizes decrease slightly as well attributing to the difference ionic radius of Ti_~(4+) ions and Zr~(4+) ions. The concentration of Zr~(4+) ions has a significant effect on the breakdown strength of Ba(Zr_xTi_(1-x))O_3 ceramics. Excellent breakdown strength and dielectric properties are achieved in the BaZr_(0.15)Ti_(0.85)O_3 ceramics sintered at 1260 ℃ for 2 h: Eb = 12.028 kv/mm, ε_r = 3334.6, tanδ = 0.005.