STRUCTURE OF CLAP GLASSES

In AlF3-based glasses (CLAP), variations of oxygen as small as 0.2 wt% are observed to have order of magnitude effects upon glass stability, to the extent that monophase glasses can be formed only at normal que nching rates when the oxygen concentration is 1.1 +/- 0.3 wt%. Glass c ompositions within this concentration band were prepared and studied b y extended X-ray absorption fine structure and Raman spectroscopy. The se data and oxygen dependence of other properties, some of which have already been reported, are used to propose a structural model based up on the coexistence of chemically perturbed regions, of the order of 1 nm in size.