Giant electrostrictive effects of NaNbO3-BaTiO3 lead-free relaxor ferroelectrics

Abstract

A giant electrostrictive effect was observed in (1 − x)NaNbO3-xBaTiO3 relaxor ferroelectric ceramics, which exhibit a high electrostrictive coefficient Q33 of ∼0.046 m4/C2 twice as large as those of Pb- and Bi-based perovskite relaxor ferroelectric ceramics. The theoretical analysis suggests that Q33 should be strongly correlated with chemical species of cations in a perovskite structure in which a strong ionic bond is of great benefit compared with a covalent bond. A hysteresis-free large electrostrictive strain of ∼0.148% up to at least 70 Hz was obtained in the x = 0.25 sample, demonstrating significant advantages over piezoelectric effects in high-precision ceramic actuators.