Fluoride glass compsns. - contg. more than 12 per cent rare earth tri:fluoride, and useful in optical, magnetic, and magneto=optical applications

Fluoride glasses transparent in the infrared region of the spectrum are claimed comprising at least 25 mole % of a fluoride or mixt. of fluorides of formula MX(X1)2 where (a) X and X1 are each F amd M is Ga, Fe, Cr, V, In or a rare earth metal; or (b) X is O and X1 is F and M is Ti; the fluoride (mixt.) contg. more than 12 mole % of trifluoride of a rare earth metal. The glasses are free of HF as formative element. In the cases where the glass contains GaF3 or InF3, it contains no more than 15 mole % BaPO3F. The parent patent permitted only 12% max. of trifluoride of a rare earth metal. It is now possible to introduce up to 40% of fluorides of divalent 3d transition elements, as well as alkali ions. The glass used in optical, magnetic and magnetic optic fields. Their refractive indices and dispersion differ widely from those of known fluoride glasses. Transmission can be achieved up to wavelengths of 12 microns, but stop at the visible regions. Introduction of cations such as Cr or rare earths such as Nd or Eu allow these glasses to be given luminescent properties, while addition of Cd confers antineutron properties. Alakali ions and certain transition metals confer ionic conductivity, also colour. NOUVEAUX VERRES FLUORES ET LEUR PREPARATION.ILS SONT CARACTERISES PAR LE FAIT QU'ILS CONTIENNENT AU MOINS 25 EN MOLES, ENVIRON, D'UN FLUORURE OU D'UN MELANGE DE FLUORURES DE FORMULE MX(X), DANS LAQUELLE:X ET X REPRESENTENT CHACUN UN ATOME DE FLUOR,ET M REPRESENTE ALORS UN METAL CHOISI DANS LE GROUPE CONSTITUE PAR LE GALLIUM, LE FER, LE CHROME, LE VANADIUM, L'INDIUM ET LES TERRES RARES,OU X REPRESENTE UN ATOME D'OXYGENE,X REPRESENTE UN ATOME DE FLUOR,ET M REPRESENTE ALORS UN ATOME DE TITANE, LEDIT FLUORURE OU MELANGE DE FLUORURES MX(X) CONTENANT PLUS DE 12 EN MOLES DE TRIFLUORURE DE TERRE RARE, ETANT ENTENDU QUE LESDITS VERRES SONT EXEMPTS D'ACIDE FLUORHYDRIQUE COMME ELEMENT FORMATEUR ET QUE, DANS LE CAS OU LESDITS VERRES CONTIENNENT UN TRIFLUORURE DE GALLIUM OU D'INDIUM, ILS NE CONTIENNENT PAS PLUS DE 15 EN MOLES DE BAPOF.