Absorption Spectra of Some Alkali Borate Glasses Containing NiO or Fe2O3 or Mixed NiO + Fe2O3

The absorption spectra of a numbers of alkali borate glasses containing nickel oxide, ferric oxide or both nickel and ferric oxides together were studied to obtain information on their structure. The experimental results were obtained analyzed and explained by assuming that nickel exists in glass as divalent nickel ions in two different states of coordination octahedral and tetrahedral while iron exists in glass as ferric and ferrous states in two different forms, octahedral and tetrahedral according to the amount of the alkali oxide content. It was found that the change in the values of position and intensity of absorption bands may change as the result to the increased d-p orbital mixing which is related presumably to the lower ligand field strength at highest alkali oxide content.