Dielectric, electrical and spectroscopic properties of barium borates of low WO₃ content

Infrared and optical absorption UV–Vis measurements, electrical and dielectric properties were carried out for glasses with the composition (mol%) 60B₂O₃·40BaO containing 0.0, 3, 5 and 9 g WO₃/100 g glass. Infrared absorption spectra of all glasses indicate the presence of both triangular BO₃ units and tetrahedral BO₄ units, and the latter is overlapped with stretching vibrations of WO₄ and WO₆ units. UV–Vis measurements reveal strong charge transfer cutoff and no absorption bands were recorded in the visible region. Upon increasing WO₃ content in the studied glasses the optical band gap (E_opt) and the electrical conductivity values increase whereas activation energy values decrease. The increase in the electrical conduction was attributed to the hopping mechanism between the two sites of tungsten (W⁵⁺, W⁶⁺). In the low frequency region below 1 kHz the dielectric constant measured at 200 Hz and room temperature was increased from 27 to 177 on increasing WO₃ content from 0.0 to 9.0 g WO₃ per 100 g glass, respectively. At 300 °C the dielectric constant reached a value of 435 for sample containing 9.0 g WO₃ per 100 g glass. The present results may make it as a promising candidate for energy storage in electronic applications.