Abstract
•Effect of nonbridging bonds on cluster formation.•Substitution of V2O5 with CuO has substantial effect on glass structure.•Decreasing bridging bonds affect the glass hardness and sound waves.•Five fold vanadate units is changed at the expense of tetrahedral units.
Glasses in the system xCuO-(80-x)V2O5-20 P2O5 with x= 0- 40 mol %. have been prepared. XRD spectroscopy confirms the amorphous nature of all as-prepared compositions.51V NMR experiments confirm increasing of nonbridging oxygen atoms (NBO) with increasing CuO. Ultrasonic velocities, both longitudinal and shear velocities decrease as CuO increases. CuO creates void spaces, causing the host network structure to weaken. The decreasing trends in both glass hardness numbers and ultrasonic longitudinal and shear velocities support that CuO enters the network to form NBO. The density increased significantly as the CuO content increased, while the molar volume decreased. Scanning electron microscopy (SEM) showed the creation of clusters species since Cu ions accumulation can be formed. Both (Cu2O) and (CuO) are the two stable copper oxide compositions in the bulk (CuO). Clusters, on the other hand, may be made up of a variety of stable components.