Random fields-triggered strain enhancement in BNT-based materials

Abstract

Bi0.5Na0.5TiO3 is regarded a potential alternative to lead-based piezoelectric materials due to its large electro-strain. Generally, the improved electro-strain is considered to arise from a relaxor-ferroelectric transition, and the random fields play a critical role. In this study, to investigate the effect of random electric field or strain field on the strain value, the dopant Sb5+, Ta5+, Zr4+, and Hf4+ are introduced into the Bi0.5(Na0.8K0.2)0.5Ti1-xBxO3 matrix, respectively. The 1% Ta5+ doped sample has the largest unipolar electro-strain, up to 0.49%, followed by the 3% Zr4+ doped sample (~0.448%). The electro-strain of 1% Sb5+ and 3% Hf4+ samples are 0.404% and 0.377%, respectively. The results show the random electric field or strain field can effectively regulate the relaxor-ferroelectric transition temperature, which enhances strain, but the strain value cannot be determined directly. The strain value is determined by the lattice structure before and after the electric field is applied.