Europium-activated lanthanide oxide phosphors prodn. - by calcining mixed oxides with mixed flux, reducing time and material consumption

摘要

A Eu-activated lanthanide (pref. Y). oxide phosphor (I), esp. a red phosphor for colour picture cathode ray tubes, is produced by calcining a mixt. of inorganic cpds. (II) of the lanthanide and Eu at 1000-1400, pref. 1200-1300, esp. 1250 degrees C in the presence of a flux (III) with at least 2 components, (II) being oxides, esp. the commercial mixed oxide, whilst (III) consists of a mixt. of salt(s) or oxide(s) (IIIa) of main gp. I, II or III elements, e.g. Na Ca or In salts, NaF, MgF2, Na3AlF6, B2O3 or Na2B4O7 and salt(s) or oxide(s) (IIIb) of main gp. III, V or VI elements, e.g. P2O5, As2O3, B2O3,Ba2B4O7, Na4P2O7 or Na2S2O3. Mixing of (II) pref. takes place in a readily volatile liquid, e.g. i-PrOH. The mixt. pref. contains 0.001-10, esp. 0.1-1 wt.% (IIIa) and 0.001-10, esp. 0.1-1 wt.% (IIIb). The calcined prod. is powdered and treated witha mixt. of inorganic and organic acids, e.g. HNO3 and citric acid for 5-120, esp. 20-30 min at 20 degrees C to remove (III). The process requires less time and material than that involving dissoln. of (II) in HNO3 or HCl, recovery of the mixed oxalate or nitrate and calcination.