Effect of sintering temperature on the piezoelectric and ferroelectric characteristics of CuO doped 0.95(Na0.5K0.5)NbO3-0.05LiTaO3 ceramics

In this paper, lead-free (Na0.5K0.5)NbO3 ceramics doped with 5 mol% LiTaO3 and 2 mol% CuO were prepared using the conventional mixed-oxide method. The samples were characterized by X-ray diffraction analysis, scanning electron microscopy, and atomic force microscopy measurements. The effect of sintering temperature on the bulk density, piezoelectric and ferroelectric properties was investigated. The results show that an increase of CuO very effectively lowers the sintering temperature and improves the electric properties of (Na0.5K0.5)NbO3-LiTaO3 ceramics. High piezoelectric properties of kp = 37.8%, kt = 50.7%, and k33 = 58.9% and ferroelectric properties Ec = 34.6 kV/cm and Pr = 22.6 were obtained for the specimen containing 2 mol% CuO sintered at a suitable temperature. Cu2+ ions acted as a hardener, which increased the Ec, Pr, and Qm values of (Na0.5K0.5)NbO3-LiTaO3 ceramics.