Optical and luminescence properties of silicon doped alumino-phosphate‑sodium glass system

Transparent thermoluminescent alumino-phosphate‑sodium glass system of 15Al2O3-35P2O5-25CaO-25Na2CO3 (all in mol%) doped with different concentrations of SiO2 were prepared by conventional melt quenching technique. X-ray diffraction (XRD) studies checked the amorphous nature of the prepared glass. Fourier Transform Infrared (FTIR) of the glass system was investigated to find the effect of SiO2-dopant concentrations on the absorption spectra in comparison with that of bulk sample (without dopants). Direct and indirect energy band gaps (Eopt) were determined and found to be in the range of 2.47-3.65 eV for m = ½ and 2.24-3.3 eV for m = 2. Refractive index (n) for each Eopt value vary from 2.42 to 2.55 and from 2.32 to 2.63 for the direct and indirect transition, respectively. Urbach energy values of the newly prepared glasses are found to be from 0.57 to 0.98 eV. In addition, effect of UV exposure on thermoluminescence (TL) sensitivity was also examined for APCNSi5 (contains 500 ppm SiO2 concentration) and a linear response to dose was obtained, indicating that this type of glass is promising as a TL dosimeter within the UV range.