Influence of annealing temperature on physical properties of NaNbO3 thin films prepared by a water-based sol-gel process

Abstract

Sodium niobate (NaNbO3, NNO) has attracted considerable attention as a potential lead-free candidate for high-density energy-storage capacitors. An economical, environment-friendly, and low-temperature-synthesized route of NNO films is highly desirable for practical applications. In this study, a novel water-based solgel route was designed for the growth of NNO films, and the effects of annealing temperatures (400-600 °C) on microstructure and physical properties were investigated. By increasing the annealing temperature, the quality of (001)-preferred NNO films was improved, but a higher annealing temperature (e.g., 600 °C) induced the secondary phase, resulting in the degradation of electrical properties. As annealed at the optimum temperature of 500 °C, the highly (001)-preferred NNO film possessed advantageous characteristics including the largest difference between maximum polarization and remanent polarization (e.g., 26 μC/cm2 at 300 kV/cm), the maximum dielectric constant, and the minimum dielectric loss (e.g., 241.68 and 0.06 at 10 kHz). These results demonstrate a promising option toward solution-processed Nb-containing perovskite oxides through water-based sol-gel routes for energy-relevant applications.