Metal fluoride glasses esp. for infrared optics - are based on zirconium or hafnium tetrafluoride with addition of other metal fluorides

• Main Author: JACQUES LUCAS, MICHEL POULAIN ET MARCEL POULAIN
• Format: Patent
• Language: English; French
• Published: 20.10.1978
• Subjects: CHEMICAL COMPOSITION OF GLASSES, GLAZES, OR VITREOUSENAMELS; CHEMISTRY; GLASS; JOINING GLASS TO GLASS OR OTHER MATERIALS; METALLURGY; MINERAL OR SLAG WOOL; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS,MINERALS OR SLAGS; SURFACE TREATMENT OF GLASS

Fluoride glass is based on a glassy tert. system of metal fluorides having a general compsn. a = moles of component A; b = moles of component B, and c= moles of component C, where a+b+c =1. The glass of the component A is ZrF4 or HyF4 (0.52-0.63 moles), B is BaF2 (0.27-0.38 moles) and C is ThF4 or UF4 or a mixt. of these two (0.02-0.15 moles). The ThF4 or UF4 of component C is pref. substitd. by a fluoride of the rare earth metals, component A being present in an amt. 0.56-0.64 moles, B in an amt. 0.30-0.36 moles and C in an amt. 0.02-0.12 moles. The glass is resistant to attack from moisture, F2, ClF3, UF6, and HF, and withstands heating in air to 350 degrees C. The glass has high transparency in the infrared region (to 8 mu m). Cheap metal oxides can be used in prodn. of the glass, by adding NH4. nHl= and effecting the conversion of the oxides to the fluorides during the melting. La combinaison de verre fluoré comprend trois constituants A, B et C qui sont tous les trois des fluorures avec des indices de composition x, y et z, dans laquelle : A est du ZrF4 ou du HfF4 , B est du ThF4 ou du UF4 , ou un mélange de ces deux corps, et C est un fluorure de terre rare, avec x, y et z définis par le domaine suivant : x 0,40-0,80 y 0,15-0,50 z 0,02-0,20 Un procédé de préparation est également décrit. Les verres sont particulièrement utilisables dans l'infra-rouge et la chimie du fluor.