Effect of alkali ions on the optical absorption bands of Ni2+ ion in alkali silicate glasses

Abstract

The Ni2+ ion was found to produce a variety of colour shades in alkali silicate glasses. The optical absorption characteristics of divalent nickel produce a strong as well as a weak absorption band at the visible region in lithium, sodium and potassium silicate glasses. In this study the molar extinction coefficients of Ni2+ ions were calculated from the intensity of the Ni2+ bands in the alkali silicate glasses. The absorption bands were found to shift towards the longer wavelength with an increase in the ionic radii of alkali ions on replacing lithia by soda and by potash. The results were discussed in the light of ligand field theory. Further, the value of molar extinction coefficient was found to increase linearly with increasing basicity parameter (B) of the alkali silicate glass.