Large and temperature-insensitive piezoelectric strain in xBiFeO3-(1-x)Ba(Zr0.05Ti0.95)O3 lead-free piezoelectric ceramics

Lead-free piezoelectric materials of xBiFeO(3)-(1-x)Ba(Zr0.05Ti0.95)O-3-1.0mol%MnO2 (BF-BZT) (0.62x0.74) were prepared by the traditional solid-state reaction process. The structure and high-temperature dielectric, ferroelectric as well as piezoelectric properties were investigated. X-ray diffraction analysis showed that BF-BZT ceramics exhibited pure perovskite structure with the coexistence of tetragonal and rhombohedral phases. Measurements of temperature-dependent dielectric permittivity revealed that BF-BZT ceramics gradually changed from the classical ferroelectrics to relaxors with increasing BZT content. The Curie temperature T-C, coercive electric field E-c (80kV/cm) and remnant polarization P-r (80kV/cm) of 0.64BF-0.36BZT ceramics were 370 degrees C, 27.8kV/cm and 24.22C/cm(2), respectively. The unipolar strain of 0.64BF-0.36BZT reached up to 0.29% (d*(33)=485pm/V), and the variation of temperature-dependent piezoelectric strain for 0.64BF-0.36BZT was about 17% from 50 to 180 degrees C, which was only 1/3, 1/2 and 1/10 of the BF-BT-, PZT-5H- and BNT-based piezoelectric ceramics, showing excellent thermal stability. These results indicated that BF-BZT ceramics were competitive candidates for lead-free piezoelectric applications.