Effect of the Annealing Conditions on the Strain Responses of Lead-Free (Bi0.5Na0.5)TiO3–BaZrO3 Ferroelectric Thin Films

Bismuth sodium titanate (Bi0.5Na0.5)TiO3 (BNT)–based thin films have attracted large attention for the production of modern precise micro–devices due to their outstanding strain responses. However, obtaining good electrical properties and low leakage current in BNT-based thin films is still a great challenge. In this work, 0.945(Bi0.5Na0.5)TiO3–0.055BaZrO3 (BNT–5.5BZ) thin films were deposited by the chemical solution deposition (CSD) method and annealed under two different conditions. This work describes a careful research study on the influence of the annealing conditions on the crystalline structure, morphology, and electrical performance of the BNT–5.5BZ thin films. The films exhibited a dense structure and excellent electrical properties following an optimized thermal treatment process. An ultra–high strain response of 1.5% with a low dielectric loss of ~0.03 was obtained in the BNT–5.5BZ thin films after post-annealing in an O2 atmosphere. The results of this work show that the enhanced strain response was mainly due to a reversible field-induced phase transition between the ferroelectric phase and the relaxation state. The post-annealing treatment is an effective method to optimize the electrical properties of BNT–based films, providing many opportunities for the application of ferroelectric devices.