Properties of glasses in the ZrF4-AlF3 -BaF2-RF (R=Li, Na or K) System

Densities, molar volumes, refractive indices, molar refractivities, glass transition temperatures and elastic constants of glasses with compositions (100-x) (0.6ZrF4&middot0.1AlF3&middot 0.3BaF2)&middotxRF, where R=Li, Na or K, were studied. All the properties vary continuously with increasing RF concentration for all three alkali atoms. The calculated molar refractivities of LiF, NaF and KF are constants which are very close to the values of the crystalline compounds LiF, NaF and KF, respectively, throughout the composition range studied, suggesting that no change occurs in the coordination state of the alkali ions by fluorine atoms. The comparison with crystalline compounds suggests that Li+, Na+ and K+ ions are all coordinated by six fluorine atoms.