Spectroscopic investigation of amber color silicate glasses and factors affecting the amber related absorption bands

Abstract

The effects of carbon, Fe2O3 and Na2SO4 contents on the amber color of glass with composition (wt%) 64.3 SiO2, 25.7 CaO, 10 Na2O were studied. The effect of some additives that could be found in glass batch or cullets on the amber related absorption band(s) was also studied. An amber related absorption band due to the chromophore Fe3+O3S2− was recorded at 420nm with shoulder at 440nm. A second amber related band recorded at 474nm with shoulder at 483nm was assigned to FeS. Increasing melting time at 1400°C up to 6h caused fainting of the amber color, decreases the intensities of the amber related bands and shifted the first band to 406nm. Addition of ZnO, Cu2O and NaNO3 to the glass produced decolorizing effect and vanishing of the amber related bands. The effects of melting time and these additives were explained on the bases of destruction the amber chromophore and its conversion into Fe3+ in tetrahedral sites or ZnS. Addition of Se intensifies the amber related bands and may cause dark coloration due to the formation of Se° and polyselenide. Amber color can be monitored through measuring the absorption in the range 406–420nm.