Structural studies and properties of CdF2-B2O3 glasses

Glasses of the composition xCdF2·(100 − x)B2O3 (40 ≤ x ≤ 75 mol%) have been studied. X-ray diffraction (XRD), infrared spectroscopy (IR) and scanning electron microscopy (SEM) were used to follow the structural changes and the effect on density and electric conduction of glasses. XRD indicated formation of crystalline phases at x = 80 mol%, including CdF2, Cd4OF6 and 3CdO⋅B2O3. SEM revealed formation of separated amorphous CdF2 clusters in all glasses and rounded crystalline particles at x = 80 mol%. IR spectra revealed that B2O3 is partially modified by CdF2, building four-coordinated boron units in the form of Cd1/22+BO3F−. The rest of CdF2 forms its own vitreous matrix. Density and molar volume have been correlated with the concentration of structural units. There is a limited increase in the electrical conductivity with CdF2 content, while the activation energy shows a maximum at ~ 60 mol CdF2. The correlation between both quantities has been discussed in terms of the parameters in Arrhenius relation.