Microstructure, phase structure, and electrical properties in lead-free (1 -x)(K_(0.40)Na_(0.60))(Nb_(0.96)Sb_(0.04))O_3-x(Bi_(0.5)Na_(0.5))_(0.9)Cu_(0.1)ZrO_3 ceramics

摘要

A new ceramic system of (1 -x)(K_(0.40)Na_(0.60))(Nb_(0.96)Sb_(0.04))O_3-x(Bi_(0.5)Na_(0.5))_(0.9)Cu_(0.1)ZrO_3 were fabricated by the conventional solid-state method, and effects of (Bi_(0.5)Na_(0.5))_(0.9)Cu_(0.1)ZrO_3 (BNCZ) contents on their phase structure, microstructure and electrical properties were investigated. It was found that the ceramics endured a series of phase structures with the addition of BNCZ, that is, orthorhombic (0) for 0 < x < 0.02, orthorhombic-tetragonal (O-T) phase coexistence for 0.02 < x < 0.035, and multiphase (R-0-1) coexistence for 0.035 < x < 0.05, as confirmed by their temperature dependence of dielectric constant and X-ray diffraction patterns. Their grain sizes firstly increased and then decreased with increasing BNCZ contents. In addition, the ceramics with x = 0.04 located at R-O&O-T phase boundaries possessed optimum electrical properties (i.e., d_(33)~415 pC/N, k_p~46%, P_r~16.08 μC/cm~2, E_c~8.53 kV/cm, strain~0.21%, and Tc~245 °C). More importantly, a good thermal stability of piezoelectricity was also shown in the ceramics with x = 0.04. We believe that this material system is one of the most promising lead-free piezoelectric candidates for practical applications.