Dielectric studies of nanocrystalline calcium tungstate

Abstract

Nanocrystalline samples of CaWO 4 were prepared at room temperature by simple chemical precipitation. The samples were characterized by X-ray diffraction and scanning electron microscopy. Energy dispersive X-ray analysis confirmed the elements present in the sample. The frequency and temperature dependence of the dielectric constant and ac electrical conductivity of the nanomaterial were investigated. Very low dielectric loss in nanocrystalline CaWO 4 powder was observed at high frequencies. The values of ac electrical conductivity calculated from the permittivity studies were found to increase as frequency increased, conforming to small polaron hopping.

Structural and Dielectric Characterization of Nanocrystalline BaWO₄

“…Dielectrics with low dielectric loss, appropriate and stable dielectric constant with temperature have a number of applications in microwave technologies. Investigation on the dielectric behavior is a useful technique for getting structural information, transport mechanism, defect behavior of a solid and may help in finding the potential application of the material [10]. BaWO4 has good dielectric properties and it is reported that the quality factor of the dielectric material BaO-TiO2 [11], (Li, RE)W2O8 ceramics (RE= Y, Yb) [11] and Ba5Nb4O15 ceramics [12] is increased and temperature coefficient of resonant frequency τf reduced to zero by introducing BaWO4 into the matrix, and is suitable for the use in microwave resonators.…”