Effect of A-Site Ion Excess on (K, Na)NbO₃ Thin Film Fabricated by Sol–Gel Non-alkoxide Process

Abstract

Lead-free (K, Na)NbO 3 (KNN) ferroelectric films were fabricated on Ti substrates by sol-gel non-alkoxide process. Nb 2 O 5 was used to prepare the soluble niobium source by citrate method. KNN thin films with perovskite phase were obtained by pyrolyzing at 500°C and annealing at 700°C. The influence of A-site ion excess on the phase, microstructure and electric properties of the films was investigated. X-ray diffraction and energy-dispersive spectroscopy (EDS) data indicate that the volatilization of K was severer than Na during the thermal treatment, and K excess is assisted to get pure perovskite phase. Meanwhile, the P-E loops and the dielectric curves manifest that K excess plays a role to improve the ferroelectric performance, while Na excess contributes to good dielectric property.