Theoretical studies of the electron paramagnetic resonance parameters and local structures for Cu2+ in (100-2x)TeO2-xAg2O-xWO3 glasses

The electron paramagnetic resonance (EPR) parameters and local structures for Cu2+ in (100-2x)TeO2-xAg2O-xWO3 (TAW) (7.5 ≤ x ≤ 30 mol %) glasses are quantitatively studied for distinct modifier concentrations x. The octahedral Cu2+ centers are subject to the medium tetragonal elongations of about 2% along the C4 axis due to the Jahn-Teller effect. By utilizing only three adjusted coefficients a, b and ω, the quantities (Dq, k, t and κ) can be suitably characterized by the Fourier type functions, which reasonably account for the experimental concentration dependences of the d-d transition bands and EPR parameters. The calculation results are discussed, and the mechanisms of the above concentration dependences of these quantities are illustrated by the modifications of the local structures and the electron cloud distribution around the Cu2+ dopant with the variations of the concentration x.