Transparent oxyflouride glass-ceramic composition and process of making

摘要

A transparent class ceramic composition includes an oxide component, a rare earth component, a halide component, and a substantially pure rare earth-halide (e.g., REF.sub.3) crystal component. A method for making a transparent oxyfluoride glass includes preparing an oxyfluoride glass containing rare earth ions by a conventional melting method and subjecting the glass to a heat treatment thereby precipitating fluoride fine crystals containing a large amount of rare earth ions.