GB1360690A - Luminescent materials - Google Patents

Abstract

1360690 Luminescent materials and uses thereof GENERAL ELECTRIC CO Ltd 16 Feb 1973 [29 March 1972] 14747/72 Heading C4S An artificial luminescent material consists of M(R 1 Mn)F 6 , where M is valency 2 and is one or more of Li, Na, K, Rb, Cs, Mg, Ca, Sr, Ba, Zn, Cd and/or the ammonium radical, R is one or more of Si, Ti and Ge, and M is tetravalent Mn as activator in the form MnF 6 <SP>2-</SP> so as to be excitable by long and/or short wavelength U.V. (i.e. # 3000 Š), cathode-rays and/or X-rays. The materials are of cubic and hexagonal systems. In the formula M(R 1-x Mn x )F 6 , x may be 10<SP>-5</SP> to 0À5 or higher. In preparation, the hexa-fluorosilicate, and/or -titanate and/or -germanate of the metal(s) M is mixed with a hexafluoromanganate of a metal M in an aqueous hydrofluoric acid solution, the solution being evaporated to dryness. The host salt may be as commercially available or prepared by reacting carbonates and oxides with a fluorinating agent. The hexafluoromanganate may be prepared from a manganate or permanganate. Alternatively, the luminescent materials may be prepared by mixing chlorides of the metals M, R and fluorinated by exposure to flowing fluorine gas either alone or mixed with inert gas (e.g. N or Ar) at 300 to 1000‹ C. Detailed preparations of potassium hexafluorosilicomanganate, K 2 Si 0À6 Mn 0À4 F 6 and potassium hexafluoromangano-titanate, K 2 Ti 0À99 Mn 0À01 F 6 are included, the latter quenching at 180‹ C. UV excitation produces narrow band red emissions, e.g. K 2 Si 0À6 Mn 0À4 F 6 emits at 629 and 634 nm. and 584, 613 and 645-647 nm., luminescence persisting up to 200‹ C. and of increasing brightness with temperature in some cases. Low and high pressure Hg lamp applications are instanced.