EPR and Magnetic Susceptibility of Na2O-CuO-P2O5 Glasses.

(50-x/2)Na2O-xCuO-(50-x/2)P2O5 glasses (x=1, 5, 15, or 30 mol%) have been prepared and characterized by electron paramagnetic resonance (EPR) and magnetic susceptibility measurements. The shape of the Cu2+ EPR spectrum depends on the Cu content, and the corresponding computer simulations suggest that the Cu2+ ions occupy two different sites in these glasses: one of them is preponderant at low Cu content and the other is preponderant at high content, in which the Cu2+-Cu2+ interactions are more important. From EPR parameters, it was found that for the site at low content, the covalency of copper ion bonding with the surrounding ligands is appreciable. The magnetic susceptibility data appear to follow the Curie-Weiss law (χ=C/(T-θp)) with negative paramagnetic Curie temperature θp indicating antiferromagnetic interactions between Cu2+ ions that are more significant in the samples with high Cu content, in agreement with EPR results. [ABSTRACT FROM AUTHOR]