Structural and Dielectric Characterization of Nanocrystalline BaWO₄

Abstract

BaWO4 samples prepared by the chemical precipitation method were structurally characterized by X-ray diffraction and scanning electron microscopic measurements. The results confirm the tetragonal scheelite-type structure of the BaWO4 sample. The dependence of εꞌ, tanδ, and ac conductivity with frequency and temperature was studied for the nanocrystalline BaWO4 calcined samples. It is found that all these factors hinge on temperature and frequency. The values of εꞌ and tanδ are high at low frequencies and their values decrease quickly with the increase in frequency. Both εꞌ and tanδ attain steady values at high frequency regime. The space charge polarization is the cause of exponential decrease of εꞌ at the low frequency. It is also found that the calcination temperature is a key factor in determining the dielectric properties of a material. The low and steady value of the dissipation factor and an almost steady value of the εꞌ suggest the suitability of BaWO4 materials in low-temperature co-fired ceramic applications. The deviation of ac conductivity against frequency comply with Jonscher’s power law, however, a small deviation in the low-frequency region is due to the Maxwell-Wagner-type effect.