Electron paramagnetic resonance and optical absorption spectra of Cu 2+ ions in alkali cadmium borosulphate glasses

Abstract

Electron paramagnetic resonance spectra at 9.205 GHz have been examined at 300 K for a series of Cu 2+ ion doped alkali cadmium borosulphate (R 2SO 4-B 2O 3-CdSO 4; R = Li, Na, K or Cs) glasses. From the observed spectra, the spin-Hamiltonian parameters have been evaluated. It was found that the spin-Hamiltonian parameters are independent of the alkali ion present in the glass. The values of the spin-Hamiltonian parameters indicate that Cu 2+ ions in alkali cadmium borosulphate glasses are present in octahedral coordination with a strong tetragonal distortion. The theoretical value of the optical basicity ( Λ th) of glasses has also been evaluated. The optical absorption spectra of Cu 2+ ion doped glasses show a single broad absorption band which is attributed to a 2 B 1g→ 2 B 2g transition. By correlating the EPR and optical data, the molecular orbital coefficient β 2 1 and the normalized covalency parameter ▪ for Cu 2+ ions have been evaluated.