Studying the Effects of Nano Sintering Additives on Microstructure and Electrical Properties of Potassium-Sodium Niobate Piezoceramics

In this paper, lead free (K0.48,Na0.52)NbO3 (KNN(48-52)) piezoelectric ceramics were made by the conventional solid-state sintering process. In order to decrease the sintering temperature and modify the dielectric, piezoelectric and ferroelectric properties, sintering additives of nano ZnO (n-ZnO), nano CuO (n-CuO) and nano SnO2 (n-SnO2) were used. Phase structure and microstructure were analyzed by using X-ray diffractometry and scanning electron microscopy techniques, and the EDX analysis was used to study the ZnO distribution at grains and grain boundaries. The highest piezoelectric constant of d33= 150 pC/N was obtained for KNN(48-52) with 0.6 mol% n-ZnO at a sintering temperature of 1070°C, which is two times larger than the pure KNN(4852) at the sintering temperature of 1112 °C. Additionally, the KNN(48-52) ceramics co-doped with 0.8 mol% nZnO, 0.5 mol% n-CuO and 0.8 mol% n-SnO2, showed dielectric and piezoelectric properties of d33= 97 pC/N, tanδ = 0.006 and εr = 172 at the sintering temperature of 960 °C, which were much better than corresponding values for pure KNN at 1110°C.