ELECTRON-PARAMAGNETIC RESONANCE AND OPTICAL-ABSORPTION SPECTRA OF CU-2+ IONS IN ALKALI CADMIUM BOROSULFATE GLASSES

Electron paramagnetic resonance spectra at 9.205 GHz have been examined at 300 K for a series of Cu2+ ion doped alkali cadmium borosulphate (R2SO4-B2O3-CdSO4; 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 Cu2+ ions in alkali cadmium borosulphate glasses are present in octahedral coordination with a strong tetragonal distortion. The theoretical value of the optical basicity (LAMBDA(th)) of glasses has also been evaluated. The optical absorption spectra of Cu2+ ion doped glasses show a single broad absorption band which is attributed to a B-2(1g) --> B-2(2g) transition. By correlating the EPR and optical data, the molecular orbital coefficient beta-1(2) and the normalized covalency parameter-pi for Cu2+ ions have been evaluated.