GB1522363A - Phosphor materials - Google Patents

Abstract

1522363 Doped alkaline-earth metal fluorophosphates DEFENCE SECRETARY OF STATE FOR 18 March 1976 [24 March 1975] 12235/75 Heading C1A [Also in Division C4] Alkaline-earth monofluorophosphates containing up to 5% of a divalent rare earth activator element based on the total molar content of the activator and alkaline earth metal and which can contain two alkaline earth metals is used as a phosphor. These compounds may be prepared in either of two methods. In one of these the activator doped compound is precipitated from an aqueous solution of a soluble salt of fluorophosphoric acid, a soluble salt of the alkaline earth metal and a soluble salt of the activator element, the precipitate is dried and then fired in a slightly reducing atmosphere at a temperature of from 800 to 1000‹C until luminescence of the phosphor material is established. In the second method ammonium fluorophosphate is fired with appropriate quantities of the oxide carbonate or nitrate of the alkaline earth metal and activator element until a stable weight is reached; this is then fired in a slightly reducing atmosphere at from 800 to 1000‹C until luminescence is established. The preferred alkaline earth metals are barium and strontium and the activator element may be europium, samarium or ytterbium. The phosphor Sr 0À98 Eu 0À02 PO 3 F and the analogous barium compound are exemplified.