EPR and Optical Absorption Spectral Investigations of Cu2+ in Bi2O3-ZnO-B2O3-Li2O Glasses

Electron paramagnetic resonance and optical absorption studies of Bi 2 O 3 -ZnO-B 2 O 3 -Li 2 O glasses were made by introducing Cu 2+ as spin probe. The EPR spectra of Cu 2+ in all the glass samples recorded in the X-band frequency have similar spectral features. The variation in glass composition influences the spin Hamiltonian parameters calculated from the spectra. The spin Hamiltonian parameters indicate that the Cu 2+ ions are coordinated with six ligand atoms in a distorted octahedron elongated along one of the axes and the ground state of the Cu 2+ isd x 2 − y 2orbital. The optical absorption spectra exhibited a broad band corresponding to d-d transition bands of Cu 2+ ion. The values of bonding parameters indicate a covalent nature for the in-plane σ bonding and pure ionic nature for the in-plane and out-of-plane π bonding. The theoretical optical basicity parameter values were evaluated, and it was observed that the value ofΓ σincreases whereasΓ π decreases with the increase in optical basicity.