Structure-optical properties of CdO glass matrix with low levels of cobalt impurities

The impacted role of cadmium oxide (CdO) on the structure-optical properties of current borate glasses with low cobalt oxide impurities was studied. The study was performed on a glass system of the formula [x CdO - (80-x) B2O3 - 0.4 CoO - 19.6 Na2O]; x = 0, 6, 12, 18 and 24 mol%, and produced by melt quenching method. Structure and optical absorption spectroscopy were done to explore the electronic transitions of Co cations inside the glass matrix. The obtained data indicated that structure and optical properties were significantly changed following CdO additives. Bands of optical absorption within both visible and near-infrared ranges showed signatures from Co2+ cations in the tetrahedral and octahedral sites, while Co3+ cations in the octahedral sites within the glass network. Optical absorption also changed significantly for the CdO-doped glasses which exhibited red shifts in visible absorption bands and blue shifts in the NIR absorption bands. The obtained absorption bands in both visible and NIR were employed to obtain the crystal field splitting parameter (Delta(t)) showing augmented records from 3364 cm(-1) to 3377 cm(-1) with more CdO addition. The Tauc gap energy values were then attained showing decreased values from 3.50 to 3.27 eV when further CdO is added. Further, the impacted role of CdO addition on the nonlinearity optical properties of the present glasses was finally estimated. Potential increases in the linear and nonlinear optical are discussed based on polarizability and basicity increments inside the glass matrix.