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

•The amber color is due two absorption bands with peaks at 420 and 478 (nm).•The two amber related bands are of different origin.•NaNO3, ZnO, Cu2O cause decolorization of the amber glass color.•Se intensifies the amber color.•Amber chromophores are converted into Fe3+ in tetrahedral sites when deteriorate.

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 420 nm with shoulder at 440 nm. A second amber related band recorded at 474 nm with shoulder at 483 nm was assigned to FeS. Increasing melting time at 1400 °C up to 6 h caused fainting of the amber color, decreases the intensities of the amber related bands and shifted the first band to 406 nm. 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 406–420 nm.

Graphical abstractDecolorization effect of ZnO added per 100 g glass on the amber bands with peaks at 420 nm and 478 nm. The decomposition rate of these bands indicates that they are of different origin.Figure optionsDownload full-size imageDownload as PowerPoint slide