We report on an environmentally friendly and versatile chemical solution deposition route to (KNN) thin films. The excess amounts of K and Na in KNN precursor solutions was found to be strong influence on perovskite KNN single-phase thin films. It was revealed from Raman spectroscopic analysis data that a change in scattering mode was observed for the KNN thin films fabricated under various processing conditions. | VNU Journal of Science Mathematics Physics Vol. 36 No. 3 2020 58-65 Original Article Microstructure and Electrical Properties of Low-temperature Solution-processed Sol-gel KNN Thin Films Vu Thu Hien1 Nguyen Thi Minh Phuong1 2 1 International Training Institute for Materials Science ITIMS Hanoi University of Science and Technology 1 Dai Co Viet Hanoi Vietnam 2 College of Industry and Trade 1 Chua Cam Trung Nhi Phuc Yen Vinh Phuc Vietnam Received 04 February 2020 Revised 09 April 2020 Accepted 24 April 2020 Abstract We report on an environmentally friendly and versatile chemical solution deposition route to KNN thin films. The excess amounts of K and Na in KNN precursor solutions was found to be strong influence on perovskite KNN single-phase thin films. It was revealed from Raman spectroscopic analysis data that a change in scattering mode was observed for the KNN thin films fabricated under various processing conditions. This change was due to the chemical composition fluctuation of K and Na in the KNN thin films during heat treatment. The leakage current and ferroelectric properties of the thin films were strongly affected by the excess amounts of K and Na as well. KNN thin films with 20 mol excess K and Na exhibited a leaky ferroelectric polarization electric field P E hysteresis. Leakage current density of the film was 10-8 A cm2 at applied field of -60 kV cm. Keywords Lead-free KNN thin film chemical solution deposition microstructure ferroelectricity. 1. Introduction Lead-free alkaline niobate ferroelectrics NaxK1-x NbO3 KNN have attracted considerable attention due to their simple perovskite structure high Curie temperature and very friendly with environment 1 . KNN actually is a solid solution of ferroelectric KNbO3 KN and antiferroelectric NaNbO3 NN . At the compositions in the vicinity of morphotropic phase boundary MPB x KNN has an orthorhombic phase at room temperature and shows enhanced piezoelectric and ferroelectric properties
