Microstructure and Piezoelectric Properties of [(K0.5Na0.5)1-xLix](Nb1-yTay)O3 Lead-Free Piezoelectric Ceramics
Li+ and Ta5+ modified lead-free piezoelectric ceramics [(K0.5Na0.5)1-xLix](Nb1-yTay)O3 have been prepared by an ordinary sintering technique. Effect of Li+ and Ta5+ on microstructure and piezoelectric properties of the ceramics was systematically studied. A morphotropic phase boundary between orthorhombic and tetragonal phases is identified in the composition range of (0.02≤x≤0.04, 0.15≤y≤0.25), which can enhance electrical properties of [(K0.5Na0.5)1-xLix](Nb1-yTay)O3 ceramics. The Curie temperature TC of these ceramics is lower than that of pure (K0.5Na0.5)NbO3 ceramics, but the temperature of orthorhombic to tetragonal phase transition TO-T of the former is higher than that of the latter. TC and TO-T both decrease as the content of Ta5+ increases. With the addition of Li+ increasing, TC increases. The optimal piezoelectric properties are obtained at (x, y)=(0.03, 0.20): piezoelectric constant d33 is 192pC/N; the electromechanical coefficient of the planar mode kp is 44%; room temperature dielectric constant εr is 1049, and the corresponding mechanical quality factor Qm is 49.
Jingtao Han, Zhengyi Jiang and Sihai Jiao
B. Xu et al., "Microstructure and Piezoelectric Properties of [(K0.5Na0.5)1-xLix](Nb1-yTay)O3 Lead-Free Piezoelectric Ceramics", Advanced Materials Research, Vols. 156-157, pp. 1522-1527, 2011