Studies of mixed former effect in EPR and optical absorption in xZnO–(75−x)Bi2O3–15B2O3–10Li2O glasses

Homogeneous glasses of the system xZnO–(75−x)Bi2O3–15B2O3–10Li2O containing 1 mol% of Cu2+ were obtained within 10≤x≤35 mol%. The spin-Hamiltonian parameters from EPR absorption spectra of Cu2+ revealed that g∥>g⊥>ge (ge=2.0023) and the ground state of Cu2+ is dx2−y2dx2−y2 orbital (2B1g state). The non-linear variation of the spin-Hamiltonian parameters with ZnO content was attributed to the mixed former effect. This effect is also evident in the optical absorption spectra. By correlating the EPR and optical absorption data, the bonding parameters α2, β2 and β12 have been evaluated and are correlated with optical basicity. In addition, the bonding parameters also varied non-linearly suggesting a mixed former effect.