Ga2O3 doping and vacancy effect in KNN-LT lead-free piezoceramics

Ga2O3 was doped into 0.95（K0.48Na0.52）NbO3-0.05LiTaO3 （KNN-LT） cera- mics and its influences on the sintering behavior, phase structure and electrical properties of ceramics were studied. Firstly, SEM observation exhibits that more and more glass phase appears in ceramics with the gradual addition of Ga2O3, which determines the continuous decrease in sintering temperatures. And the addition of Ga2O3 is also found to increase the orthorhombic-tetragonal transition temperature （To-T） of system to a higher level. Secondly, both the density and the coercive field （Ec） of ceramics increase firstly and then decrease with increasing the Ga2O3 content, and the KNN-LT-xGa sample at x = 0.004 shows a pinched P-E hysteresis loop. Finally, the impedance characteristics of KNN-LT-xGa ceramics were investigated at different temperatures, revealing a typical vacancy related conduction mechanism. This work demonstrates that Ga2O3 is a good sintering aid for KNN-based ceramics, and the vacancy plays an important role in the sintering and electrical behaviors of ceramics.