Investigation of oxygen defects in chromium-doped borosilicate glass co-doped with alkali metal (Na2O) and transition metal (ZnO) for photonic applications

A series of chromium borosilicate glasses double doped with Na 2 O and ZnO are prepared by melt quenching technique. Field Emission Scanning Electron Microscope (FESEM) showed a uniform distribution of ZnO within the glass matrix. Fourier-transform infrared (FT-IR) spectroscopy identified borate-oxygen defects while optical absorbance revealed that chromium Cr 2 O 3 is composed of Cr 6+ and Cr 3+ oxidation states. X-ray photoelectron spectroscopy (XPS) validated the presence of borate and chromium-related defects via O1s, B1s, and Cr peaks. The substitution of Na 2 O with ZnO as polarizable component, proved presence of Zn 2+ and Zn 4+ cations which enables ZnO to act as both roles of glass modifier and a former. The evaluated optical linear refractive index and extinction coefficient in the spectral range 400–2500 nm showed an increase in the refractive index which is attributed to zinc’s high polarizability and limited tendency for tetrahedral coordination. The optical energy gap is positively correlated with increasing ZnO content in mol.%. The impact of ZnO concentration on wavelength at zero material dispersion (λ WZMD ) was also calculated and compared to silicate and germinate glasses proved suitability of the studied glass for photonic applications particularly data transmission in the wavelength range 1.6024–1.8855 μm. Thermal parameters were calculated using differential scanning calorimetry (DSC) to evaluate glass forming ability dependence on the introduced ZnO.