Structural study of heat-treated BaTiO₃–KNbO₃ nanocomposites with heteroepitaxial interface by synchrotron radiation powder diffraction

抄録

KNbO₃ (KN)/BaTiO₃ (BT) nanocomposite ceramics, in which a BT nanoparticle is thinly coated with KN crystals through the heteroepitaxial interface, are heat-treated at 1000°C for 10 h, and the crystal structures are investigated by synchrotron radiation powder diffraction. The Rietveld analysis based on the multicomponent models reveals that the volumes of gradually distorted tetragonal components of BT are significantly decreased and the BT-KN solid solutions emerge in the nanocomposites by the heat-treatment. The suppression of the piezoelectric response in the heat-treated nanocomposites compared with the as-synthesized ones is attributed to these changes in the crystal structure. The core/multishell structure model for the ceramic grain is proposed, and the changes in the crystal structure are revealed to be caused at the heteroepitaxial interface regain between BT and KN.