High electrostrictive effect in La3+-doped Ba(Zr0.2Ti0.8)O3 lead-free ferroelectrics

Abstract

Perovskite ferroelectric ceramics with Tm (temperature corresponding to maximum dielectric permittivity ε′) around room temperature and high electrostrictive coefficient Q33 are of interest to the applications in high-precision actuators, since low-hysteresis/non-hysteresis and high strain response can be generated in these materials based on a purely electrostrictive effect. In this work, undoped Ba(Zr0.2Ti0.8)O3 (BZT) and La3+-doped Ba(Zr0.2Ti0.8)O3 (BLZT) lead-free ferroelectrics were synthesized by solid state reaction method. Their dielectric and ferroelectric properties were investigated systematically with an emphasis on electrostrictive effect. With respect to increase of La3+ content from 0 to 1%, the Tm of BLZT decreases from 44.5 °C to 14.6 °C, and the diffuseness degree γ increases from 1.814 to 1.993. A conductive mechanism, which is prominent in undoped BZT, is inhibited drastically by introducing the La3+ into BZT. A high electrostrictive strain of 0.08% and a low hysteresis η (<10%) are obtained simultaneously in x = 0.25% composition at room temperature. The Q33 ranges from 0.0377 m4/C2 and 0.0537 m4/C2. This work not only reports a high electrostrictive effect in BLZT ferroelectrics, but also provides BLZT ceramics with a potential application in high-precision actuators.