Grain orientation and anisotropy in the physical properties of SrBi2(Nb1 - xVx)2O9 (0 ≤ x ≤ 0.3) ceramics.

SrBi₂(Nb_{1 - x}V_x)₂O₉ (0 ≤ x ≤ 0.3 in molar ratio) ceramics have been fabricated via conventional sintering at elevated temperatures. Interestingly sintering the pellets in the 1320–1470 K temperature range yielded partially grain oriented ceramics. The orientation factor (f) monitored via X-ray powder diffraction studies was found to increase with increasing V₂O₅ content and reached 83% for x = 0.3. The increment in (f) was not that significant with increase in sintering temperature and its duration. The microstructural studies suggest that V₂O₅ has a truncating effect on the abnormal platy growth of SBN grains. The dielectric constant (ℇ_r) and loss (D) measurements as functions of both temperature and V₂O₅ content have been carried out along the directions parallel (ℇ_rp) and perpendicular (ℇ_rn) to the cold pressing axis of the pellet. The anisotropy (ℇ_rn/ℇ_rp) associated with ℇ_r was found to be 1.11 at 300 K and 2.1 at the Curie temperature, (T_c) respectively. Different dielectric mixture formulae that were employed to analyze the effective dielectric constants of these samples with varying porosity confirmed that the experimental value of ℇ_r was comparable with that obtained using Wiener's formula. Impedance spectroscopy was employed to rationalize the electrical behavior of these ceramics. The pyroelectric coefficients along the directions parallel and perpendicular to the pressing axis of the grain oriented (83%) SBN ceramic at 300 K were 0.13145 mC/m²K and 0.26291 mC/m²K respectively. The ferroelectric properties of these grain-oriented ceramics were better in the direction perpendicular to the pressing axis than those in the parallel direction. [ABSTRACT FROM AUTHOR]