B-site Substitution Effects on the Piezoelectric Properties of Bi-based Lead-free Ceramics

B-site substitution with isovalent and donor impurities was compared in terms of the piezoelectric properties of Bi-based ABO3 perovskite ceramics. X-ray diffraction study revealed that both impurities bring about degradation in their ferroelectric properties as well as piezoelectric characteristics. However, there existed a difference between the isovalent and heterovalent impurities that influence a phase transformation of ferroelectric anisotropic-to-electrostrictive pseudocubic symmetry. Based upon analyses including the crystal, microstructure, dielectric, ferroelectric properties, we believed that A-site vacancies in the ABO3 ceramic significantly contribute to a ferroelectric-nonpolar phase transition, which give rise to lead to a giant strains. The present paper will discuss the origin of giant strains in Bi-based perovskite ceramics.