Role of structure gradient region on dielectric properties in Ba(Zr,Ti)O3-KNbO3 nanocomposite ceramics

Crystal structures of KNbO3 (KN)/BaZrxTi1−xO3 [BZT, (0.1 ≤ x ≤ 1)] nanocomposite ceramics have been investigated using synchrotron radiation X-ray powder diffraction, where BZT nanoparticles thinly coated with KN crystals through the heteroepitaxial interface are sintered. The Rietveld analysis based on the multicomponent model reveals that the ceramic grain has the core/multishell structure consisting of a BZT core, distorted BZT and KN multishells. The variations of the volume ratio of the distorted BZT shell region corresponding to the structure gradient interface region and the dielectric property of the ceramics show similar trends as a function of x. From these results, we propose that the structure gradient region is electrically soft, and provides a crucial contribution to the dielectric properties of the nanocomposite ceramics.