Excellent piezoelectric performance of BiFeO3–BaTiO3– La(Mg2/3Nb1/3)O3 lead-free ceramics via relaxation regulation near the morphotropic phase boundary

Abstract

Although BiFeO3–BaTiO3-based lead-free ceramics have attracted much attention in recent years as a high temperature piezoelectrics, their d33 value is still difficult to exceed 200 pC/N through conventional methods. In this work, a novel (0.7-x)BiFeO3-0.3BaTiO3-xLa(Mg2/3Nb1/3)O3 (x = 0–0.005) ternary system was reported to own excellent room-temperature piezoelectric constant (d33) ∼216 pC/N and high Curie temperature (480 °C) at x = 0.003 simultaneously. It reveals that the compositions undergo an obvious phase transition from ferroelectric (FE) rhombohedral (R) phase to relaxor pseudo-cubic (PC) phase via an R–PC morphotropic phase boundary (MPB). More importantly, piezoelectric nonlinear Rayleigh analysis and S-E/P-E curves suggest that the significantly enhanced domain dynamics due to the coexistence of macrodomain and nanodomain can be observed in the x = 0.003 sample. The synergy of these two effects induce the improved d33 value observed in the x = 0.003 sample. In addition, the compositions exhibit the inhibition of defect dipoles and the improvement of the high temperature resistivity, leading to the excellent thermal stability with sensitivity coefficients ƞ less than ± 5% in the annealing temperature range of 25–400 °C. The present work provides a guideline for the subsequent design of high-temperature lead-free ceramics.