Electron Paramagnetic Resonance and Optical Absorption Studies of PbF2-SrO-B2O3-LiF Glasses Containing Cu+2 Ions

Abstract

Electron paramagnetic resonance (EPR) and Optical absorption studies of  xPbF₂-(30-x) LiF-15SrO-54B₂O₃-1CuO glasses have been done by introducing a transition metal ion Cu⁺² ion as a spin probe with fixed mole% in the given glass composition. Glasses containing transition metal (TM) ion give the information of site symmetry around the Cu⁺² ion of the host glass. The EPR spectra of Cu⁺² in all glass samples recorded in the X-band frequency have similar features. The spin-Hamiltonian parameters have been calculated, the observed values are g_|| > g_^> g_e and A_|| > A_^.  It suggests the site symmetry around Cu⁺² ion is tetragonal distorted octahedral and the ground state of Cu⁺² is d_x²_-y² (²B_1g) orbital. The Cu⁺² ion is coordinated with six ligand atoms in a distorted octahedron site symmetry. Calculated bonding parameters suggest the covalent nature of in-plane s-bonding (a²) and pure ionic nature for out of a plane (β²) and in-plane p-bonding (β₁²). This data is correlated with the theoretical optical basicity (L_Th) values and it is observed that G_s value increases whereas G_p values decrease with increasing L_Th.