Enhanced electrical and thermoelectric power properties of BaWO sub(4)/CaWO sub(4) nanocomposites

Abstract

Powdered xBaWO sub(4)/(1-x)CaWO sub(4) where (x=0,0.25,0.5,0.75,1) nanocomposites were synthesized by the co-precipitation method at room temperature (RT). We are reporting DC and AC conductivity and dielectric properties of nanocomposites at room temperature (RT). Structural characterization and HRTEM image confirm interface formation of the nanocomposites. The current density-electric field (i.e., J-E) characteristics of the nanocomposites' studies reveal excellent varistor behavior. Dielectric properties were measured in the frequency 20 Hz-3 MHz at room temperature (RT). The dielectric constant was found to be higher for C2 (0.5BaWO sub(4)/0.5CaWO sub(4)) nanocomposites as compared to single phase and was maximum for atomic ratio (Ba/Ca) with optimal value of 'x'. DC conductivity (sigma sub(dc)), calculated from Jonscher's power law, of C2 (0.5BaWO sub(4)/0.5CaWO sub(4)) nanocomposites interfaced is higher than that of single phase, respectively. Enhanced AC conductivity is also observed for C2 (0.5BaWO sub(4)/0.5CaWO sub(4)) nanocomposites. These enhanced electrical properties of C2 (0.5BaWO sub(4)/0.5CaWO sub(4)) nanocomposites are due to the space charge layer (SCL) formation at the interface. In detail, conduction models for all the nanocomposites are explained. Thermopower investigations on the nanocomposites resulted in Seebeck coefficient (S) showing a transition from negative to positive values with confirmation n-type semiconductors at room temperature (RT). The enhanced power factor of C3 (0.75BaWO sub(4)/0.25CaWO sub(4)) nanocomposites is at higher temperature as compared to other nanocomposites. This C2 (0.5BaWO sub(4)/0.5CaWO sub(4)) nanocomposite can be considered as an efficient multifunctional nanocomposites due to its enhanced optical and electrical properties, and C3 (0.75BaWO sub(4)/ 0.25CaWO sub(4)) nanocomposite is very good efficient thermoelectric power devices at higher temperature application.