Dielectric and pyroelectric anisotropy in the melt-quenched barium bismuth niobate ceramics

BaBi2Nb2O9 textured ceramics were fabricated via melt-quenching followed by high temperature (800–1000 °C) sintering process. The resulting ceramics possessed a {00l} texture with the a–b plane of the grains oriented parallel to the major face of the quenched plate. The influence of the sintering temperature on the orientation factor (f) and microstructure was evaluated via X-ray powder diffraction (XRD) and Scanning electron microscopy (SEM). The orientation factor was found to increase with increase in the sintering temperature and reached a maximum value of 0.47 for the samples sintered at 1000 °C for 10 h. Relative density and the grain-size of the ceramics were found to increase with increase in the sintering temperatures. The effect of texture on the dielectric and pyroelectric properties was evaluated. The measurements performed along the direction perpendicular to the pressing axis exhibited superior values than that of the direction parallel to the pressing axis. The observed anisotropy in the physical properties was attributed to the increased contribution from the highly polarizable a–b planes which are oriented in the direction perpendicular the pressing axis.