STRUCTURAL AND DIELECTRIC-PROPERTIES OF BI2NBXV1-XO5.5 CERAMICS

Bi2NbxV1-xO5.5 ceramics with x ranging from 0.01 to 0.5 have been prep ared. The crystal system transforms from an orthorhombic to tetragonal at x greater than or equal to 0.1 and it persists until x = 0.5. Scan ning electron microscopic (SEM) investigations carried out on thermall y etched Bi2NbxV1-xO5.5 ceramics confirm that the grain size decreases markedly (18 mu m to 4 mu m) with increasing x. The shift in the Curi e temperature (725 K) toward lower temperatures, with increasing x, is established by Differential Scanning Calorimetry (DSC). The dielectri c constants as well as the loss tangent (tan delta) decrease with incr easing x at room temperature.