Effect of HfO_2 content on the microstructure and piezoelectric properties of (Bi_(0.5)Na_(0.5))_(0.94)Ba_(0.06)TiO_3 lead-free ceramics

摘要

(Bi_(0.5)Na_(0.5))_(0.94)Ba_(0.06)TiO_3-xHfO_2 [BNBT-xHfO_2] lead-free ceramics were prepared using the conventional solid-state reaction method. Effects of HfO_2 content on their microstractures and electrical properties were systematically studied. A pure perovskite phase was observed in all the ceramics with x=0-0.07 wt%. Adding optimum HfO_2 content can induce dense microstructures and improve their piezoelectric properties, and a high depolarization temperature was also obtained. The ceramics with x=0.03 wt% possess optimum electrical properties;;(i.e., d_(33)～ 168 pC/N, K_p～32.1%, Q_m～130,ε_r～715, tan δ-0.026, and T_d～106°C, showing that HfO_2-modified BNBT ceramics are promising materials for piezoelectric applications.