Optical Spectra of Chromium in Borate and Silicate Glasses

Optical absorption spectra have been obtained on Cr3+ in alkali borate, alkali silicate and alkaline earth borate glasses. The assignments for bands ν1∼ν5 were made on the basis of octahedrally coordinated Cr3+ in the glasses and their band positions were determined. The values of three parameters, namely the crystal field strength, Dq, the Racah B and Racah C parameters, were calculated.The results indicate that;(1) Dq value of alkali borate glasses increases with increasing concentration of alkali oxide up to about 15mole% but it changes anomalously in the composition range of 15∼20mole%.(2) Dq value of alkaline earth borate glasses increases with increasing concentration of alkaline earth oxide.(3) On the contrary, in alkali silicate glasses the value decreases with increasing alkali oxide content.(4) As for the effect of kind of ion an increase of Dq value of the glass is in the order Li2O>Na2O>K2O and CaO>SrO>BaO for the same molar concentration of the oxide