Phase transition, microstructure, and electrical properties of Ca, Zr, and Sn-modified BaTiO_3 lead-free ceramics

摘要

In this work, the (Ba_(1-x)Ca_x)(Ti_(0.94)Sn_(0.03)Zr_(0.03))O_3 (BCTSZ-x) lead-free ceramics were prepared by the conventional solid-state method, and effects of Ca~(2+) content on their phase structure, microstructure, and electrical properties were investigated. The phase structure of the ceramics endures a series of the phase transitions from orthorhombic, orthorhombic-tetragonal, to tetragonal phase as the Ca~(2+) content increases. Their grain size gradually drops as the Ca~(2+) continues increasing, the dense microstructure is developed, and the Ba~(2+), Ca~(2+), Ti~(4+), Sn~(4+), and Zr~(4+) are homogenously distributed in the ceramic matrix. In addition, adding Ca~(2+) can not decrease the Curie temperature of the BCTSZ-x ceramics. Enhanced dielectric, ferroelectric, and piezoelectric properties (e.g., ε_r~3783, tanδ~1.3%, P_r~ 11.1 μC/cm~2, d_(33) ~ 359, and k_p ~ 0.45) were observed in the ceramic with x = 0.08 owing to the involved O-T phase boundary. As a result, the addition of Ca~(2+) can effectively enhance the piezoelectricity of barium titanate-based ceramics without the decrease of T_c.