GB1110290A - Europium-activated yttrium-gadolinium oxide type phosphors - Google Patents

Abstract

Europium activated yttrium - gadolinium oxide type phosphors are manufactured by employing yttrium oxide and/or gadolinium oxide as host, adding suitable europium compounds, the Eu content preferably being 0.01 to 0.2 gram atom per 1 mol of Y2O3 or Gd2O3, further adding as fluxes at least one of the ammonium halides other than ammonium flouride and metal element halides, preferably 1 to 10 mol per cent for cathode ray excitation and 5 to 100 mol per cent for U.V. excitation, grinding resulting mixture, then heating to at least 1000 DEG C., the higher the better, suitably 1200 DEG C., for from 10 mins. to several hours, preferably 2 hours. Ten examples of preparation are described with a wide variety of starting materials including compounds of Y, Gd, Eu, Cl, Br, I, Ba, Na, Zn, Ca, Mg, Cd, Sr, Al and In, one phosphor prepared having emission peaks at 6115<\>rA and 6130<\>rA. Detailed comparisons are given of the fluorescence efficiencies of phosphors with various fluxes and varying amounts of Y2O3 and Gd2O3. The halides of metals disclosed are those Na, K, Ca, Sr, Ba, Mg, Zn, Cd, Al, Ga, In in monovalent or trivalent states for example. The phosphor is considered suitable for fluorescent lamps, fluorescent high pressure mercury discharge tubes, and as the red phosphor in colour television. Excitation frequencies of 2537<\>rA and 3650<\>rA are instanced.