A correlated electron diffraction, in situ neutron diffraction and dielectric properties investigation of poled (1-x)Bi0.5Na0.5TiO3-xBaTiO3 ceramics

A correlated electron diffraction, temperature-dependent in situ neutron diffraction, and temperature-dependent dielectric properties investigation of poled (1-x)Bi0.5Na0.5TiO3-xBaTiO3 (BNTBT100x) (x = 0.04, 0.07, and 0.12) samples has been carried out. The results show that the depolarization temperature, Td, of the rhombohedral BNTBT 4 sample is associated with the disappearance of G ± ½ [111]*p satellite reflections and a-a-a- octahedral tilting while that of the BNTBT 12 sample is associated with a metrically tetragonal to metrically cubic or pseudo-cubic symmetry. In the case of the poled BNTBT 7 sample in the MPB region, the dielectric properties show a quite distinct two stage transition from a room temperature clearly metrically tetragonal phase again to a metrically cubic or pseudo-cubic symmetry above 150 °C. There is no apparent change in its average structure in vicinity of Td in BNTBT 7. Electron diffraction shows the presence of considerable octahedral tilt twin disorder in all three samples.