MICROSTRUCTURE, ELECTRICAL PROPERTIES AND PROCESSING DEPENDENCE OF CuO MODIFIED (Na0.52K0.48)NbO3 CERAMICS

The CuO modified (Na0.52K0.48)NbO3 (NKN) piezoelectric ceramics were prepared by a solid-state reaction method. On the one hand, CuO doping can improve the densification behavior and simultaneously promote the grain growth, however, has little effect on the Curie temperature. On the other hand, the mechanical quality factor Qm obviously increases, the dielectric loss tanδ decreases, and the piezoelectric constant d33 and the planar electromechanical coupling coefficient kp tend to drop. Moreover, an obvious effect comes from the sintering conditions. The 1mol% CuO doped NKN ceramics sintered at 1090 °C for 3 h own the electrical properties: Qm = 1727, tanδ = 0.29 %, d33 = 74 pC/N, kp = 0.22 and a dielectric constant εr = 410. All these effects of CuO doping are considered to result from the liquid phase and oxygen vacancies formed during sintering.