Impact of TeO₂ on the structure, optical, and photoluminescence characteristics of BaO–V₂O₅ –P₂O₅ vitreous materials

Abstract The objective of the current study is to assess the structural , optical filter property, and photoluminescence of a glass system primarily made of barium phosphate doped with vanadium pentoxide (V 2 O 5 ), in which the structural units of phosphate (P 2 O 5 ) are replaced by tellurium oxide (TeO 2 ). The phosphate network consists of PO 4 units in Q 2 and Q 3 modes, while TeO 2 exists as trigonal pyramid TeO 3 units. Density decreased from 3.263 to 3.046 g cm −3 with TeO 2 addition up to 15%, then increased to 3.486 g cm −3 at 20% TeO 2 . Depending on the TeO 2 concentration, the addition of TeO 2 to the glass network produces a region with zero transmittance that extends from 672 nm to 998 nm. Furthermore, a cut-off wavelength in the visible and near-infrared (NIR) range was observed in every glass sample. The visible and near-infrared (NIR) cut-off wavelengths of the glass containing 5 mol% TeO 2 are 510 nm and 998 nm, respectively. The cut-off wavelengths of the other samples were lower than those of the 5% TeO 2 sample. The optical band gap rose from 2.08 to 2.166 eV as the TeO 2 content increased from 5 to 20 mol%, while the refractive index dropped from 2.703 to 2.668, respectively. The color purity (CP%) of the glasses is enhanced by the intercalation of TeO 2 into the barium phosphate network. The base sample presented a color purity of 19%, which increased to 71% and 82% with a TeO 2 contribution of 5 and 10 mol%. However, the color purity decreased to 38% at 20 mol% of TeO 2 due to the network former effect of TeO 2 .