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

摘要

Although BiFeO3-BaTiO3-based lead-free ceramics have attracted much attention in recent years as a high temperature piezoelectrics, their d(33) value is still difficult to exceed 200 pC/N through conventional methods. In this work, a novel (0.7-x)BiFeO3-0.3BaTiO(3)-xLa(Mg2/3Nb1/3)O-3 (x = 0-0.005) ternary system was reported to own excellent room-temperature piezoelectric constant (d(33)) similar to 216 pC/N and high Curie temperature (480 degrees 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 signif-icantly 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 d(33) 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 eta less than +/- 5% in the annealing temperature range of 25-400 degrees C. The present work provides a guideline for the subsequent design of high-temperature lead-free ceramics.

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