Effects of annealing temperature on structure and electrical properties of (Na, K)NbO sub(3) thin films grown by RF magnetron sputtering deposition

In this study, lead-free (Na, K)NbO sub(3) films were successfully deposited by RF magnetron sputtering and subsequent annealing treatment, in which a KNN atmosphere was projected to prevent the alkali metal volatilization. Effects of annealing temperatures on structure and electrical properties of the KNN thin films were investigated systematically. The results show that, with the temperature increasing, the KNN films started crystallization accompanying with volatilization of alkaline elements as well as phase transition. The particle size and surface quality of the film closely depended on annealing temperature and atmosphere. The (100) preferred orientation, large grain size, dense morphology, and annealing atmosphere all benefited the electrical properties of the KNN films. Notablely, the KNN films deposited at 200 degree C and subsequent annealed at 650 degree C showed a well polarization of 2P sub(r) = 20.8 mu C/cm super(2 ) and coercive field 2E sub(c) of 200 kV/cm.