Effects of CaTiO3 addition on microstructures and electrical properties of Na0.52K0.48NbO3 lead-free piezoelectric ceramics

Abstract In this article, various amounts of CaTiO 3 (CT) were added into (Na 0.52 K 0.48 )NbO 3 (NKN) ceramics using conventional oxide-mixing method for improving NKN's properties. The experimental results show that the (1− x )(Na 0.52 K 0.48 )NbO 3 – x CaTiO 3 ( x =0∼0.07) solid solution system can be successfully synthesized. Addition of CaTiO 3 not only effectively prevents materials from deliquescence, but also improves the density and the electrical properties of the ceramics. The dielectric constant–temperature ( e r − T ) curves exhibit that the temperatures of the Curie point ( T c ) and the phase transition from tetragonal to orthorhombic ( T O − T ) are decreasing monotonously as the amount of CT addition is increased. A morphotropic phase boundary (MPB) can be found in the (1− x )NKN− x CT solid solution system as the doping amount of x =0.03, and the 0.97NKN–0.03CT ceramics, with a high bulk density, 98% theoretical density, and an appropriate grain size of about 1∼2 μm, present a superior domain switching ability and the optimum properties: d 33 =117 pC/N, k p =0.39, P r =21 μC/cm 2 , and T c =333 °C.