Physical, Optical and Electron paramagnetic resonance studies of PbBr2- PbO-B2O3 glasses containing Cu2+ ions

The glasses with the composition PbBr2- PbO-B2O3 glasses containing Cu2+ ions were prepared by melt quenching technique. X-ray diffractograms revealed the amorphous nature of the glasses. Density and molar volume were determined. Density is found to decrease while the molar volume increases with increase of PbBr2 content. The optical absorption spectra exhibited a broad band corresponding to the d-d transition of Cu2+ ion. From optical absorption spectra E-opt and Urbach energies were determined. Electron Paramagnetic Resonance (EPR) studies were carried out by introducing Cu2+ as the spin probe. Glasses containing transition metal((TM)) ions such as Cu2+ give the information about the structure and the site symmetry around the TM ions. EPR spectra of all the glass samples were recorded at X-band frequencies. From the EPR spectra spin-Hamiltonian parameters were evaluated. It was observed that g(vertical bar vertical bar) > g(perpendicular to)> ge (2.0023) and A(vertical bar vertical bar)> A(perpendicular to). From this values it is concluded that the ground state of Cu2+ is d(x2-y2) (B-2(ig)) and the site symmetry around Cu2+ ion is tetragonally distorted octahedral. From the EPR and Optical data bonding co-efficients were evaluated. The in plane sigma-bonding(alpha(2)) is moderately ionic while out of plane pi-bonding(beta(2)) and in plane pi-bonding(beta(2)(1)) are ionic nature