Influence of Zr/Ti ratio on the dielectric properties of BaZr_xTi_1−xO₃ ceramics for high-voltage capacitor applications

Ba(Zr_xTi_1−x)O₃ ceramics are prepared via the conventional solid state reaction method. The Zr⁴⁺ ions have diffused into the BaTiO₃ 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)O₃ ceramics are systematically discussed. The high porosities of Ba(Zr_xTi_1−x)O₃ ceramics deteriorate seriously the dielectric constant, dielectric loss and the breakdown strength. When the concentration of Zr⁴⁺ ions increase from x = 0.05 to x = 0.20, the Curie temperature T_c decreases slightly from 120 to 60 °C, the grain sizes decrease slightly as well attributing to the difference ionic radius of Ti⁴⁺ ions and Zr⁴⁺ ions. The concentration of Zr⁴⁺ ions has a significant effect on the breakdown strength of Ba(Zr_xTi_1−x)O₃ ceramics. Excellent breakdown strength and dielectric properties are achieved in the BaZr_0.15Ti_0.85O₃ ceramics sintered at 1260 °C for 2 h: Eb = 12.028 kv/mm, ε_r = 3334.6, tanδ = 0.005.