High and temperature-stable electrostrain in lead-free environmentally friendly BiFeO3-BaTiO3 piezoelectric ceramics

Currently, environmental pollution and industrial effluents are depleting soil, water, and aquatic life and pose serious concerns to climate change. Environmentally friendly piezoelectric materials are considered potential agents for industrial applications, as they can generate clean energy by applying mechanical forces. High and temperature-insensitive piezoelectric strain is an ever-increasing demand in lead-free ceramics. In this work, a lead-free La-doped BiFeO3-BaTiO3 composition is designed at the crossover boundary of normal-relaxor ferroelectrics. The properties are optimized as a function of sintering temperature (Ts) from 960 to 1000 °C. An enhanced and thermally stable converse piezoelectric constant (d33∗) of 760 ± 23 pm/V over a wide range of 25–150 °C is achieved at an optimized TS of 980 °C. This high electrostrain response is mainly attributed to the low energy barrier for domain switching due to multiple-point crystal structure morphotropic phase boundary. Additionally, the high Curie temperature (TC) of 355 °C with excellent piezoelectric strain performance of our work are promising results for high-temperature piezoelectric actuators. The framework of chemical composition design and phase engineering of this work could inspire further development of lead-free ceramics for industrial applications.