The effect of composition on UV–vis–NIR spectra of iron doped glasses in the systems Na2O/MgO/SiO2 and Na2O/MgO/Al2O3/SiO2

Glasses with the compositions xNa2O · 10MgO · (90 − x)SiO2, 10Na2O · xMgO · (90 − x)SiO2, 5Na2O · 15MgO · xAl2O3 · (80 − x)SiO2, xNa2O · 10MgO · 10Al2O3 · (80 − x)SiO2, 10Na2O · 10MgO · xAl2O3 · (80 − x)SiO2, 10Na2O · 5MgO · 10Al2O3 · (80 − x)SiO2 were melted and studied using UV–vis–NIR spectroscopy in the wavenumber range from 5000 to 30 000 cm−1. At [Al2O3] > [Na2O], the UV-cut off is strongly shifted to smaller wavenumbers and the NIR peak at around 10 000 cm−1 attributed to Fe2+ in sixfold coordination gets narrower. Furthermore, the intensity of the NIR peak at 5500 cm−1 increases. This is explained by the incorporation of iron in the respective glass structures.