Process for making bulk heavy metal fluoride glasses

Claim 1

A process of manufacturing a bulk heavy metal fluoride glass, said process comprising the steps of: obtaining constituent fluoride compounds of said heavy metal fluoride glass in as pure a form as possible; selectively refining said compounds by sublimation to obtain higher purity compounds; minimizing contamination of said compounds by the ambient atmosphere; weighing each of said compounds to obtain a desired composition of said heavy metal fluoride glass; mixing said compounds together to form said desired composition; forming a charge of said composition; loading a crucible with said charge; placing said crucible in a crystal growth furnace; sealing said furnace; evacuating said furnace; backfilling said furnace with an inert gas; creating a reactive atmosphere in said furnace to remove undesirable chemical groups from said charge; heating said charge to a charge fusion temperature to cause said charge to melt; allowing said charge to react with said reactive atmosphere; raising a temperature of said charge above said fusion temperature to insure admixture of molten constituent compounds of said charge; raising said charge to a higher temperature above an admixture temperature for a period of time, said charge reaching said higher temperature in about 1 to 2 hours from the start of said heating; lowering a temperature of said charge in a short period of time to a temperature less than said fusion temperature, said charge forming a bulk glass, in situ; removing said crucible from said furnace; and removing said bulk glass.