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

Abstract

Infrared and optical absorption UV-Vis measurements, electrical and dielectric properties were carried out for glasses with the composition (mol%) 60B 2 O 3 Á 40BaO containing 0.0, 3, 5 and 9 g WO 3 /100 g glass. Infrared absorption spectra of all glasses indicate the presence of both triangular BO 3 units and tetrahedral BO 4 units, and the latter is overlapped with stretching vibrations of WO 4 and WO 6 units. UV-Vis measurements reveal strong charge transfer cutoff and no absorption bands were recorded in the visible region. Upon increasing WO 3 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 (W 5? , W 6? ). 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 WO 3 content from 0.0 to 9.0 g WO 3 per 100 g glass, respectively. At 300°C the dielectric constant reached a value of 435 for sample containing 9.0 g WO 3 per 100 g glass. The present results may make it as a promising candidate for energy storage in electronic applications.

Role of Mn/Cr dual-doped ZnO nanoparticles of diluted magnetic semiconductors: influence on structural and electrical properties

“…Figure 4 presents the variation of log σ ac as a function of frequency in the range from 0.042 kHz to 1 MHz for all samples at room temperature (298 K). A plateau region of the independent-frequency is appearing at lower frequencies which match with DC conductivity [51,52]. On the other hand, the AC conductivity is more frequency-dependent at higher frequency regions.…”

Optical properties of selected 4d and 5d transition metal ion-doped glasses

“…4(c) presumably arises from one of these two reasons but the attribution is unclear. Abdelghany and co-workers have studied various W-doped glasses with or without the action of ionizing radiation [53][54][55] and have interpreted the presence of W 5+ and W 6+ ions. From literature data for MWO 4 compounds (M ¼ Mg, Ca, Sr, Ba, Pb) a reasonably linear t (R 2 adj ¼ 0.9560, N ¼ 5) is obtained for our plot of charge transfer emission band maximum (between 420-470 nm) against cation crystal radius (not shown).…”