SECOND PHOTON VISIBLE EMITTING PHOSPHOR AND DEVICE UTILIZING SAME

1304211 Luminescent materials and uses thereof WESTERN ELECTRIC CO Inc 16 April 1970 [16 April 1969] 18163/70 Heading C4S [Also in. Division H1] A composition of matter contains material of formula Ba(M x RE y Yb 1-x-y ) α X 2+3α in which M is at least one element selected from Y, Lu, Gd, Ce, Sc, La, Ga, In, and Al, RE is at least one of Er and Ho, X is at least one halogen, x is from 0 (including zero) to 0À95, y is from 0À01 to 0À3 and α is 0À05 to 4. Preferably X is F, (or may be Br, Cl, I), x is from 0 to 0À82, y is from 0À03 to 0À2 and α from 0À4 to 3, e.g. 0À6 to 1À5 or 1. The composition may be a phosphor coating (8) on a silicon doped GaAs electroluminescent diode with a ring cathode (6) (Fig. 1, not shown), or a single crystal (21) in a laser pumped by GaAs diodes (25) (Fig. 3, not shown). For oscillation of the laser, layers (22) and (23) of a series of dielectric layers for instance, may be completely and partially reflecting respectively. An enveloping structure may be utilized and circular junctions and end pumping may be employed. Interstitial F, Li1+ or anion vacancies may charge compensate and in absence of complete compensation some alpha ions are divalent. Any ceramic forming preparation including mixing and firing may be used, and for coating a glass matrix of respective index approaching that of the phosphor (e.g. 1À7) may be included. The BaF is preferably initially purified, e.g. zone refined in HF or inert gas and subsequently firing of trifluorides prepared by reacting the oxide with HF may be in a Bridgman crucible to nucleate single crystal growth details of preparation being given. Exemplified compositions. are BaY 0À1 Yb 0À8 Er 0À1 F 5 , BaYb 0À9 Er 0À1 F 5 , Ba Y 0.8 Yb 0.1 Er 0.1 F 6 , BaLu 0.5 Yb 0.45 Er 0.05 F 5 , BaY 0À1 Yb 0À8 Ho 0À1 F 5 , and BaY 0À5 Yb 0À45 Er 0À05 Cl 5 and preparations disclosed. Various crystallographic structures are considered, and when applied as a layer the phosphors may be admixed with glass to improve adhesion and reduce scattering, the matrix material having a refractive index approaching that of the phosphor. Scattering is also reduced by the elimination of impurities during zone refining.