Williamson–Hall analysis and the dielectric behavior of complex perovskites (BaM0.9M′0.1)0.984O3 (M=Ti, Zr; M′=Nb, Ta)

Abstract

The long range average structure and local distortions of perovskite type solid solutions (BaTi0.9M′0.1)0.984O3 and (BaZr0.9M′0.1)0.984O3 (M′=Nb, Ta) were examined by high-resolution synchrotron X-ray diffraction. A Rietveld refinement indicated that all four solid solutions had simple cubic symmetry, where the lattice volume varied according to the size of the cationic constituents. As revealed by Williamson–Hall analysis and scanning electron microscopy, both (BaTi0.9M′0.1)0.984O3 had denser and enlarged grains than the parental BaTiO3, and had anisotropic microstrain that are indicative of the non-periodic atomic displacements along the [100] directions of the cubic cell. (BaTi0.9Nb0.1)0.984O3 and (BaTi0.9Ta0.1)0.984O3 exhibited relaxor-like dielectric behavior with Curie temperatures of 230K and 195K, respectively. On the other hand, (BaZr0.9Nb0.1)0.984O3 and (BaZr0.9Ta0.1)0.984O3 showed almost unchanged dielectric behavior compared to that of BaZrO3.