Dielectric and electrical characteristics of Nd2(Ba0.5R0.5)2O7 (R = W, Mo) ceramics

Polycrystalline samples of Nd-2(Ba0.5R0.5)(2)O-7 (R = W, Mo) were synthesized using a high-temperature solid-state reaction technique. A preliminary structural (XRD) analysis of these compounds show the formation of a single-phase orthorhombic system at room temperature. The scanning electron microscopic (SEM) study with different magnifications provides information on quality of these samples and the uniform grain distribution over the entire surface of the samples. Detailed studies of dielectric constant (er and loss tangent (tan 6)) as a function of frequency (50-10(4) Hz) at different temperatures (300-623 K) revealed that the compounds do not have any dielectric anomaly in the studied frequency and temperature range. The nature of variation of (dc) resistivity at three different temperatures, and its variation with temperature (similar to 300-623K) at a constant electric field (50V/cm) showed the semiconductor characteristics of the materials. (c) 2007 Elsevier B.V. All rights reserved.