Fabrication and characterization of grain-oriented bismuth vanadate ceramics

Grain-oriented (GO; 79%), high density (96% of the theoretical value) ceramics of bismuth vanadate, Bi2VO5.5, have been fabricated via a liquid-phase-aided two-stage sintering process. Scanning electron microscopy (SEM) was employed to monitor the crystallite size and the morphology of the starting powders and the microstructure of the sintered ceramics. X-ray diffraction (XRD) studies were carried out to verify the grain-orientation in the ceramics. The dielectric constant and the conductivity studies carried out along the directions perpendicular and parallel to the pressing axis show significant anisotropies (1.7 and 5.3, respectively, at 300 K). The grain-oriented ceramics were found to exhibit improved ferroelectric properties, with higher remnant polarization (P-r) and lower coercive field (E-c) than those of the randomly oriented (RO) ceramics. (C) 1997 Elsevier Science Ltd.