Abnormal piezoelectric and dielectric behavior of 0.92Na0.5Bi0.5TiO3-0.08BaTiO3 induced by La doping

Abstract

Properties and phase structures of lead-free piezoelectric ceramics 0.92Na0.5Bi0.5TiO3-0.08BaTiO3 (NBT-BT) modified with La2O3 have been studied. Because of the different valence and ionic radius between La3+ and the exchangeable A-site ions, the lattice distortion and arrangement in the modified compounds can be expected, which will directly influence the phase composition and electrical characteristics of NBT-BT. Differing from familiar frame of gradual variability going with adulteration, NBT-BT doping 0.2–1.0 at.% La2O3 presents an abnormal increase of dielectric constant and a dramatic vanish of piezoelectricity. Further study on the relaxor property and domain structure implies that it originates from a typical relaxor-to-antiferroelectric crossover phase transition. However, a larger addition of La2O3 could rejuvenate the ferroelectricity and piezoelectricity of NBT-BT, correlating well with the model of competing ferro- and antiferroelectric interactions and metastable intermediate phase behavior in the morphotropic phase boundary region of complex perovskites.