Glasses in the xCuO-(80-x)V₂O₅-20 P₂O₅ system with 0 ≤ x ≤ 40 mol% were prepared by slowly cooling technique. XRD spectra have confirmed the amorphous structure of the all investigated samples. Effects of exchange of V₂O₅ with CuO on the results based on ⁵¹V NMR spectroscopy were specifically studied. It is found that V₂O₅ plays a dual role, as network modifier and a network former. Both the phosphate and vanadate network structures were depolymerized by CuO. The change in the values of chemical shifts of ⁵¹V NMR is a measure for depolmerization process. In the V₂O₅ rich glasses, both pentavalent (V₅) and tetrahedral (V₄) vanadium atoms are formed. On the other hand, V₅ concentration is decreased and V₄ units containing non bridging oxygen atoms (NBO) is alternatively increased upon increasing CuO and decreasing in V₂O₅ concentrations. Increasing CuO at the expense of V₂O₅ results in the formation of (NBO) in the main glass network. Increasing of NBO leads to creation of more open spaces which can play the role of weakening in the structure that can be reflected by decreasing the glass hardness with increasing CuO content. In the field of application, the mixed former amorphous vanadium phosphate network is recommended as a good model for semiconducting material in which the conduction mechanism would be accessible by both Cu cations and electron transition between the valance states of vanadium atoms. In addition, the layer structure of V₂O₅-P₂O₅ is characterized by its good ability for storing energy between different multilayers. This issue needs a further studies which will be considered in a future work.

Solid State NMR, Vanadium-Phosphate Glasses, Structure and Hardness