STRUCTURAL INVESTIGATIONS OF FLUORIDE GLASSES

Abstract

New fluoride glasses have been synthesized in ternary and quaternary systems based on NbOpF-BaFo-RF where RF are the alkali fluoride, LiF, NaF, KF and mixed fluoride NaF-LiF. These glasses were prepared by the usual melt-quench technique. The effect of RF instead of NbOF on the glass forming range, physical properties and structure investigations of the produced fluoride glasses have been studied. Glass densities were determined by the use of Archmedes' method and so the corresponding molar volume were calculated. The physical properties of these glasses such as thermal properties have· been carried out by applying the DSC technique. This has been done in order to find endothermic peak due to the glass transition temperature Tg, exothermic peak due to the glass crystallization Te and endothermic peak due to the melting temperature Tm. From these results the glass stability factor S and the activation energy of crystallization .Ea have been calculated. Also, thermal expansion coefficient a and specific heat Cp were determined. The optical properties of the present new glasses such as the refractive index np has been measured and so the molar refractivity Ra has been calculated. From the dielectric theory, the relationship between the refractive index and number of ions /unit volume (N/V) with polarizability o' has been discussed. UV• spectra have been measured. in order to calculate the opti_cal energy