Fluoride glasses

Crystalline fluorides play a significant role in materials science, e.g. as lenses in infrared (IR) optics (CaF2), laser hosts (LaF3, CaF2), fast ion conductors (βPbF2), and fluoride ion sensitive electrodes (LaF3). Their melts, however, are very fluid, largely ionic, and unlikely candidates for glass formation. Nevertheless, many fluoride glass forming systems have been identified, with useful properties such as extended IR transmission, and the added advantage of ease of fabrication. The development of these materials, with special emphasis on optical fibers, is considered in this paper. Fluoride glasses are often referred to by acronyms based on the initial letters of the component cation chemical symbols, in a sequence based more on historical development than amounts present. Examples include ZBLAN(ZrF4-BaF2-LaF3-A1F3-NaF), CLAP (CdF2-LiF-A1F3-PbF2), and BZnYbT (BaF2-ZnF2-YbF3- ThF4) glasses. ZBLAN glasses have been studied in most detail and are the basis of much of the discussion here