Materials Research Bulletin, Vol.43, No.11, 3026-3036, 2008
Dielectric and pyroelectric anisotropy in melt-quenched BaBi2(Nb-1 (-) V-x(x))O-9 ceramics
The (0 0 l) textured BaBi2(Nb-1 (-) V-x(x))(2)O-9 (where x = 0, 0.03, 0.07, 0.1 and 0.13) ceramics were fabricated via the conventional melt-quenching technique followed by high temperature heat-treatment (800-1000 degrees C range). The influence of vanadium content and sintering temperature on the texture development and relative density were investigated. The samples corresponding to the composition x = 0.1 sintered at 1000 degrees C for 10 h exhibited the maximum orientation of about 67%. The Scanning electron microscopic studies revealed the presence of platy grains having the a-b planes perpendicular the pressing axis. The dielectric constant and the pyroelectric co-efficient values in the direction perpendicular to the pressing axis were higher. The anisotropy in the dielectric constant is about 100 (at 100 kHz) at the dielectric maximum temperature and anisotropy in the pyroelectric co-efficient is about 50 mu C cm(-2) degrees C-1 in the vicinity of pyroelectric anomaly for the sample corresponding to the composition x = 0.1 sintered at 1000 degrees C. Higher values of the dielectric loss and electrical conductivity were observed in the direction perpendicular to the pressing axis which is attributed to the high oxygen ion conduction in the a-b planes. (C) 2007 Elsevier Ltd. All rights reserved.