Optical Absorption of Cobalt in Alkali Borate Glass with Halide Ingredient

The conversion of octahedral cobalt (II) into tetrahedral symmetry has been studied in alkali borate glass, i. e., Li2O-B2O3, Na2O-B2O3, K2O-B2O3, with addition of halide by processing absorption spectroscopy in the ranging of wavelength 350-2000 millimicrons. The results of measurement are shown in Fig. 3-Fig. 11. Addition of halide to alkali borate glass intensifies the cobalt (II) absorption and modifies the absorption spectra considerably. In the two kinds of glass 10Na2O·90B2O3 and 20Na2O·80B2O3 (mol. %), with halogen X (X=Cl, Br or I) ingredient, the co-ordination number of cobalt (II) converts the octahedral into the tetrahedral configuration present as CoO6→CoX4. In the glass 30Na2O·70B2O3 the addition of halogen causes decrease in intensity of absorption spectra with increase in halogen concentration as the result of the changing CoO4→CoO6→CoX4. The effect of varying the kind of alkali is negligible. The density of the glass in degree was also determined.