Effect of V2O5 on structural and elastic properties of alkali silicate SiO2–Na2O–NaF glasses

A series of V2O5–doped alkali silicate SiO2–Na2O–NaF glasses were prepared by the melt quenching technique. Amorphousness of the samples was characterized using powder X-Ray diffraction (XRD) analysis; and the structural role of V2O5, Na2O and NaF in the silicate network was explored using Fourier Transform Infrared (FTIR) spectroscopy. Elastic properties, determined by using ultrasonic technique, were correlated with the compositional and structural parameters as well as the excess molar volume. The substitution of SiO2 by Na2O and NaF in the base SiO2–Na2O–NaF glass resulted in the breaking of Si–O–Si linkages and creation of NBOs, whereas the addition of V2O5 resulted in formation of VO5 structural units and weak V–O–V and Si–O–V linkages. Makishima-Mackenzie's theory is valid for pure SiO2 and V2O5–free glasses. The discrepancy between theoretical and observed elastic moduli and micro-hardness of V2O5–doped glasses was discussed in details.