LAUSR

Abstract Multi-component CaF 2 −ZnO–Bi 2 O 3 −P 2 O 5 glasses doped with different concentrations of CoO (ranging from 0 to 1.0 mol %) were crystallized by heat treatment. These samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), EDS and differential thermal analysis (DTA) techniques. The XRD patterns have indicated the presence of various phases viz., Ca 3 (PO 4 ) 2 , Bi 3 PO 7 , CaZn 2 (PO 4 ) 2 , Bi(PO 4 ), Zn 3 (PO 4 ) 2 , ZnCo(P 2 O 7 ), CaCoP 2 O 7 , ZnCo 2 O 4 , CoF 2 , Co 3 O 4 and CoF 3 . Conventional spectroscopic studies such as optical absorption, FTIR and Raman were also carried out on these glass ceramic samples. The analysis of these results has indicated that cobalt ions exist in both Co 2+ and Co 3+ states in the glass ceramic network. These studies have further revealed that the rigidity of the glass ceramic network decreases up to 0.6 mol% of CoO. Beyond this concentration the insulating strength of the prepared samples is found to increase.