| 摘要 |
1311954 Luminescent materials WESTERN ELECTRIC CO Inc 4 Aug 1970 [7 Aug 1969] 37463/70 Heading C4S [Also in Division C1] Fluoride compounds which contain ytterbium together with yttrium or any of the other rare earths of the lanthamide or actonide series, and which are used in up-converting phosphor layers, are crystallized by growth from a flux which contains at least 1% by weight of a fluoride of at least one of the elements Be, Mg, Al, B, Si and P. The fluxes, such as BeF 2 , MgF 2 , or AlF 3 for instance have a high oxygen affinity, and reduce oxygen contamination of the phosphor. The flux may also contain one or more of the compounds PbF 2 , BiF 3 , LiF, NaF, KF, RbF, CsF, TlF and ScF 3 and initially at least 1% by weight of NH 4 F. The fluoride compounds may also contain a halogen other than fluorine (Cl, Br, I specified) in an amount of up to 80 atom percent of total halogen present. Preferred phosphor compositions contain ytterbium together with the ions of at least one of the elements erbium, thulium and holium and may also include ions of yttrium, barium, strontium, gadolinium, lutetium, lanthanum, sodium or lithium. Materials of primary interest as phosphors have the formulµ: R.E.F 3 ; M<SP>1</SP>R.E.F 4 ; M<SP>1</SP>R.E. 3 F 10 ; M<SP>11</SP> x R.E. 1-x- F 3-x and M<SP>111</SP> x R.E. 1-x F 3 in which M<SP>1</SP> is Li or Na, M<SP>11</SP> is Ca, St or Ba, M<SP>111</SP> is scandium, aluminium, gallium or indium, R.E. is ytterbium together with any other rare earth element and x is from 0 to 0À95. The examples describe the crystallization of compounds of the formulµ Y 0À8 Yb 0À19 Er 0À01 F 3 ; and Y 0À65 Yb 0À25 Tm 0À001 F 3 detailed preparations being given. The compounds of the invention may be used in an infra-red emitting diode (Fig. 1) comprising a gallium arsenide diode 1 containing a p-n junction 2 defined by p and n regions 3 and 4 respectively, the diode being forward biased by planar anode 5 and ring cathode 6. Infra-red radiation produced by junction 2 and represented by arrows 7 passes into and through layer 8 of phosphor material where it is converted to radiation at a visible wavelength; and in an infra-red diode pumped laser (Fig. 2) comprising a single crystal rod 21 provided with protecting layers 22 and 23, and a light source made up of infra-red-emitting diodes 25 of the type shown in Fig. 1. Tb, Eu, Sm, Dy, and Fe impair fluorescence, as does Tm with Ho or Er as activators. Other impurities up to 1% by wt. may be tolerated. |
