Prospective of (BaCa)(ZrTi)O ₃ lead-free piezoelectric ceramics

Piezoelectric ceramics is a functional material that can convert mechanical energy into electrical energy and vice versa. It can find wide applications ranging from our daily life to high-end techniques and dominates a billion-dollar market. For half a century, the working horse of the field has been the polycrystalline PbZr _1−x Ti _x O ₃ (PZT), which is now globally resisted for containing the toxic element lead. In 2009, our group discovered a non-Pb piezoelectric material, (BaCa)(ZrTi)O ₃ ceramics (BZT-BCT), which exhibits an ultrahigh piezoelectric coefficient d ₃₃ of 560–620 pC/N. This result brought extensive interest in the research field and important consequences for the piezoelectric industry that has relied on PZT. In the present paper, we review the recent progress, both experimental and theoretical, in the BZT-BCT ceramics.