Visible and far-infrared spectroscopic studies of Co-doped (80-x)Sb2O3-20Na2O-xWO3 glasses

We investigate the absorption of the glasses (80-x)Sb2O3-20Na(2)O-xWO(3) (x mol% of WO3) in the spectral regions 12 500-28 571 and 2000-7800 cm(-1). The samples are doped with 0.01, 0.03 or 0.05 mol% of Co3O4 and x = 30%. The observed absorption band is due to the Co impurity in the visible spectral region. This absorption band of glasses does not contain information on the exact energy position of the Co levels. Therefore, we have calculated the second derivative of absorption. It has been established that Co2+ ions are surrounded by distorted octahedral coordination in the investigated glasses. The energy level structure of the Co2+ ion in the samples is also presented. We have calculated the crystal field parameter Dq and the Racah parameters B and C.