METHOD OF PRODUCING FLUORIDE GLASS WITH WIDE INFRARED TRANSMISSION BAND Russian patent published in 2014 - IPC C03C4/10 C03C3/32 

FIELD: chemistry.

SUBSTANCE: method of producing fluoride glass includes melting a charge mixture of starting components in an inert atmosphere in a platinum or carbon crucible, pouring the melt into a metal casting mould and cooling the melt in the mould. The charge mixture consisting of a mixture of halides selected from: HfF₄; BaF₂; BaCl₂; LaF₃; AlF₃; InF₃; NaF; NaBr is further mixed with 2-3 mol% of barium hydrofluoride which is predried at temperature of up to 100°C. The charge mixture is fed into the crucible, which is placed in an ampoule made of quartz glass, heated in a current of inert gas to decomposition temperature of the hydrofluoride and held for 20-40 minutes. The crucible is then closed with a graphite cork and the gap between the cork and the wall of the crucible is filled with powdered glass of the same composition, after which the metal casting mould is placed in the top part of the ampoule. The ampoule is sealed, washed with inert gas and placed in a two-zone resistance furnace. The crucible is heated to a temperature which is 250-350°C higher than the melting point of the charge mixture and held for 30-50 minutes, after which the temperature is lowered by 120-160°C, and the mould located in the top part of the ampoule is heated in the second zone of the resistance furnace to a temperature which is 35-45°C below the glass-transition point. The melt is then cooled and the obtained glass is removed from the mould.

EFFECT: method enables to obtain chlorine- or bromine-containing fluoride glass with low concentration of oxygen-containing impurities and prevents evaporation of heavy halides.

4 cl, 1 tbl, 1 dwg, 3 ex