Evolution of crystal structure of Ba and Ti co-doped BiFeO3 ceramics at the morphotropic phase boundary

Crystal structure of the Bi(1-x)Ba(x)Fo(1-x)Ti(x)O(3) ceramics across the phase boundary region between the polar rhombohedral and pseudo-cubic phases has been investigated by means of X-ray and neutron diffraction, scanning electron microscopy and differential scanning calorimetry techniques. The structural measurements have revealed a decrease in the rhombohedral distortions upon increase in the dopant content followed by the stabilization of the pseudo-cubic phase at x >= 0.20. While temperature increase gives rise to the similar pattern of structural changes for the lightly-doped samples, an unpredictable temperature-driven strengthening of the rhombohedral distortions has been found for the compounds belonging to the phase boundary region. The study specifies the peculiarities of the temperature-driven evolution of the crystal structure depending on the structural state of the compounds at room temperature. (C) 2019 Elsevier B.V. All rights reserved.