Temperature-insensitive piezoelectricity in lead-free NaNbO3-based ceramics

In this work, we report a lead-free piezoelectric ceramic of (0.9-x)NaNbO3-0.1BaTiO(3)-xBaZrO(3), and the effects of BaZrO3 on the phase structure, microstructure, electrical properties and temperature stability are investigated. A morphotropic phase boundary-like region consisting of rhombohedral (R) and tetragonal (T) phases is constructed in the compositions with x = 0.035-0.04. More importantly, insitu temperature independence of the piezoelectric effect {piezoelectric constant (d(33)) and strain} can be achieved below the Curie temperature (T-c). Intriguingly, the electric field-induced strain is still observed at T >= T-c due to the combined actions of the electrostrictive effect and the electric field-induced phase transition. We believe that NaNbO3-based ceramics of this type have potential for applications in actuators and sensors.