Large electrostrain with good temperature stability in sodium niobate based ceramics

Abstract

A large electrostrain of 0.24% with a converse piezoelectric constant of 790 pm V-1 was obtained from the LiSbO3 and (Bi0.5Na0.5)(Zr0.9Sn0.1)O3 modified KNbO3 ceramics. The electrostrain showed good temperature stability with vibration within 3% in the range from room temperature to 200 °C. It can even rival the current working horse PZT4. Besides, the present ceramics exhibited a large d33 of 207 pC N-1. The enhanced piezoelectric properties were achieved by pinching the phase with different symmetries together, experimentally by doping. Here the isovalent additive LiSbO3 was employed to lower the tetragonal to orthorhombic phase transition temperature and to raise the orthorhombic to rhombohedral phase transition temperature, i.e. pinch the three ferroelectric phases together. Meanwhile (Bi0.5Na0.5)(Zr0.9Sn0.1)O3 was used as the aliovalent doping to lower the Tc. It consequently resulted in a decrease of polarization anisotropy between phases with different symmetries and thus led to a large piezoelectric performance.