Controlling the domain size to enhance the piezoelectricity of BiFeO3–BaTiO3via heterovalent doping

Abstract

We demonstrate a novel concept of domain engineering to simultaneously achieve outstanding piezoelectricity (d₃₃ ∼ 191 pC N⁻¹) and high Curie temperature (T_C ∼ 485 °C) in BF ceramics by adding elements with high valence difference. It is revealed that the NaTaO₃ additive contributes to tuning the relaxor characteristics and the configuration of macrodomains and nanodomains in the nonergodic state (0.725-x)Bi_1.05FeO₃–0.275BaTiO₃-xNaTaO₃–0.3% MnO₂, leading to heterogeneous domain structures with rhombohedral-tetragonal phase coexistence. In addition, temperature-dependent piezoelectric characterization studies exhibit a continually increasing d₃₃ with the increase of temperature in this system, and an ultrahigh piezoelectric constant (d₃₃ = 516 pC N⁻¹) can be found at the composition of x = 0.008 when the temperature reaches 320 °C. Combined with in situ XRD and first-principles calculations, we confirm that the enhancements of d₃₃ and P_r in the BF–BT ceramics during the heating process have an intrinsic contribution from the phase transition of R3c to R3m. This work not only provides a concept to obtain ceramics with both excellent piezoelectricity and Curie temperature but also helps understanding the intrinsic origin of unusual high-temperature d₃₃ in BF–BT-based materials, which is useful for further developing BF-based piezoelectric materials.