Theoretical analysis for ultrasonic properties of vanadate-phosphate glasses over an extended range of composition: Part II

Makishima-Mackenzie`s theory and Abd El-Moneim`s semi-empirical formulas were used to predict the compositional dependence of ultrasonic properties in binary V ₂O ₅-P ₂O ₅ (45 mol% ≥ V ₂O ₅ ≤ 85 mol%) glasses at room temperature and at 8 MHz frequency. Anomalous behavior between the calculated dissociation energy per unit volume of the glass and ultrasonic properties was discussed in terms of the basic structural units that constituting the glass network. Values of the dissociation energy per unit volume of the glass were calculated from the average single bond strengths proposed by Dimitrov and Komatsu for chemical bonds in the basic structural units of V ₂O ₅ and P ₂O ₅ oxides. The ring deformation model has also been used to estimate the mean atomic ring size of the glass network from data of bulk modulus and average first-order stretching force constant of V-O-P linkages. It has been found that, the average single bond strengths of P O bonds in PO ₄ groups and V O bonds in VO ₄ and VO ₅ groups play a dominant role in correcting the anomalous behavior between the calculated dissociation energy per unit volume of the glass and ultrasonic properties. Values of the theoretical elastic moduli, which have been calculated on the basis of Makishima-Mackenzie`s theory, are in a very good agreement with the corresponding experimental ones. Moreover, Abd El-Moneim`s semi-empirical formulas, which correlate ultrasonic attenuation coefficient with the corrected dissociation energy per unit volume, mean atomic ring size, oxygen density and packing density, appear to be valid for the investigated glass samples.