Europium activated lanthanide metal oxide phosphor prodn. - using several high temp. calcination stages, improving red quality

摘要

In the prodn. of a Eu-activated lanthanide metal oxide phosphor, esp. a red phosphor for colour cathode ray tubes, in which a mixt. of inorganic cpds. of the lanthanide metal and Eu is opt. calcined at 400-1000 degrees C and subjected to at least one high temp. calcination process at 1000-1400 degrees C, the improvement comprises subjecting the mixt. to at least one, pref. 2 or 3 more high temp. calcination processes at 1000-1400, pref. 1250-1300 degrees C, pref. for 5-350, esp. 40 min. and pref. with intermediate cooling to 18-300, esp. 50 degrees C and thorough mixing after cooling. Pref. phosphates e.g. alkali phosphates, pyrophosphates and/or polyphosphates can be used as flux, which is added to the mixt. at 300-1000 degrees C before calcination. Better red quality at the same or even reduced Eu content and the same luminescent yield as usual.