Site engineering and polarization characteristics in (Ba_(1-y)Ca_y)(Ti_(1-x)Hf_x)O_3 lead-free ceramics

摘要

Here we improved both piezoelectricity and strain of BaTiO_3-based ceramics using composition designs and the optimization of poling conditions. In this work, the (Ba_(1-y)Ca_y)(Ti_(1-x)Hf_x)O_3 lead-free ceramics were fabricated by a conventional solid-state reaction method, and we systematically investigated the composition dependence of their phase structures, microstructure, electrical properties, and polarization characteristics. A multiphase coexistence concerning rhombohedral-orthorhombic and orthorhombic-tetragonal (R-O/O-T) was observed in the ceramics with a: = 0.10 and y = 0.15, and then an enhanced piezoelectricity of d_(33)～540 pC N~(-1) and a large strain of ～0.21% can be attained. More importantly, a larger d_(33) can be reached when sintered at 1450 ℃ and polarized at their corresponding phase transition temperatures. We believe that this investigation can benefit the development of barium titanate ceramics.