Elastic properties of Na2O-ZnO-ZnF2-B2O3 oxyfluoride glasses

Abstract

Elastic properties of Na 2 O-ZnO-ZnF 2 -B 2 O 3 oxyfluoride glasses with different ZnF 2 concentrations have been investigated using ultrasonic velocity measurements at room temperature, at a frequency of 10 MHz. Glasses prepared by melt quenching method were suitably polished for the ultrasonic velocity measurements using pulse-echo superposition method. Various elastic moduli have been calculated and their compositional dependence has been examined. The compositional dependence of elastic moduli with the concentration of ZnF 2 shows decrease in the moduli initially, with further increase in ZnF 2 the moduli sharply increases and then again tend to decrease when ZnF 2 concentration is 20 mol%. The values of Poisson's ratio lie in the range of 0⋅24-0⋅30, which is typical to covalent bonded network. The variation of θ D with ZnF 2 indicates complex behaviour of the glass network. The results have been analysed in view of the modified borate glass network. Addition of ZnF 2 into the pure glass seems to influence the borate network by replacement of B-O-B linkages with B-O-Zn.