Tetragonal Distortion of a BaTiO<sub>3</sub>/Bi<sub>0.5</sub>Na<sub>0.5</sub>TiO<sub>3</sub> Nanocomposite Responsible for Anomalous Piezoelectric and Ferroelectric Behaviors
Wen‐Xiong Zhang, Qi Feng, Eiji Hosono, Daisuke Asakura, Jun Miyawaki, Yoshihisa Harada
Abstract
Ferroelectric mesocrystalline nanocomposites are functional materials with improved ferroelectricity via lattice strain engineering. In this study, X-ray diffraction (XRD) and soft X-ray absorption spectroscopy (XAS) are performed to determine the tetragonal distortion of Bi0.5Na0.5TiO3 (BNT) in a ferroelectric mesocrystalline BaTiO3 (BT)/BNT nanocomposite. The XRD results demonstrate the expansion of the BNT lattice in the BT/BNT nanocomposite. Using Williamson–Hall analysis, the tensile strain of BNT in BT/BNT-700 is confirmed. Shift and splitting of the eg orbital are observed for BNT in the BT/BNT nanocomposite in Ti L3-edge XAS, suggesting the lower symmetry of the TiO6 octahedron in BNT, which is ascribed to a significant tetragonal distortion of BNT in the BT/BNT nanocomposite caused by the lattice mismatch between BNT and BT. It is found that the tetragonally distorted BNT in BT/BNT is responsible for the anomalous ferroelectric response of the mesocrystalline BT/BNT nanocomposite.