Investigation of the magnetic properties in strontium-borate vanadate glasses

To further elucidate the nature of the valence state of V ions in vanadate glasses, magnetic susceptibility measurements in the temperature range of 5 to 300 K have been performed on a series of vanadium-strontium-borate (V ₂O ₅+SrO+B ₂O ₃) oxide glasses with V ₂O ₅ concentrations greater than 50 mol%. The magnetic susceptibility for these oxide glasses is found to consist of a temperature-independent paramagnetic contribution arising from V ₂O ₅ and a Curie-Weiss temperature-dependent contribution associated with magnetic V ⁴⁺ ions being present in concentrations between 2% and 10% of the total V concentration. The negative Curie-Weiss temperatures in the range of 0 to -2.8 K indicate a weak antiferromagnetic interaction between the V ⁴⁺ ions. These results are consistent with a glass network structure consisting of VO ₅ polyhedra in which the V ⁴⁺ would be predominantly isolated species, and any interactions between the V ⁴⁺ ions would result from superexchange interactions through V-O-V bonds.