Dielectric Anisotropy in PartiallyGrain-Oriented Bi2VO5.5 Ceramics

Ceramics obtained from quenching melts of prereacted polycrystalline Bi2V5.5 exhibit grain orientation (~ 55%). Microstructural studies carried out using scanning electron microscopy (SEM) on subsequently annealed ceramics show ferroelectric domains. These post-annealed ceramics possess dielectric anisotropies of about 1:1.2 at 300 K and 1:4.3 in the vicinity of the Curie temperature (~ 730 K) between the directions parallel and perpendicular to the quenching direction. The dielectric constants of the samples, obtained by quenching the melts, are higher than that of the post-annealed ceramics. Electrically poled and thermally cycled samples of both as-quenched and post-annealed exhibit ferroelectric hysteresis loops at 300 K.