Electron Paramagnetic Resonance and Optical Absorption Studies of Cu2+ Probe in Li2O-TeO2-CdO-As2O3-B2O3 Glasses

Abstract

Electron paramagnetic resonance (EPR) and Optical absorption studies of xLi₂O-(30-x)TeO₂-5As₂O₃-5CdO-59B₂O₃-1CuO (where x=5, 10, 15, 20 and 25  mol%) glasses were carried out by introducing  ion as the spin probe. The glasses were prepared by the melt quenching method. The EPR spectra of all the glass samples were recorded at room temperature and at X-band frequencies. The EPR spectra exhibited similar spectral features. The spin-Hamiltonian parameters were calculated from the EPR spectra using standard procedures. The  ions are in well defined axial sites but subjected to small distortion leading to the broadening of the spectra. It was observed that . The spin-Hamiltonian parameter values indicated that the ground state of   ion is   orbital  and the site symmetry around Cu²⁺ ions is tetragonally distorted octahedral. The optical spectra were recorded in the range 300-800nm. By correlating EPR and optical data, the bond parameters were evaluated and the values show purely ionic nature for the in-plane σ bonding and in-plane π bonding. The out-of-plane π bonding is moderately covalent. The theoretical optical basicity parameter values were evaluated and it was observed that the value of Γ_σ increases, whereas Γ_π decreases with the increase in optical basicity.