Method of preparing a luminescent Eu2+ activated strontium aluminate, aluminate obtained by said method and low-pressure mercury vapour discharge lamp provided with such an aliminate.

摘要

Method of preparing a luminescent Eu<2><+> activated strontium aluminate defined by the formula Sr4Al14O25:Eu<2><+> in which a mixture comprising SrO, Al2O3 and Eu2O3 or compounds yielding these oxides upon an increase of temperature is heated in a weakly reducing atmosphere at a temperature of 1100 to 1500 DEG C, in which per mol of the Al present a combination of between 0.1 and 5 mol % of B2O3 or compounds yielding B2O3 upon an increase of temperature, and between 0.1 and 10 mol % of at least one of the fluorides and/or chlorides of Ba, Sr, Cs and/or Al and/or RbCl is added to the mixture as a flux, whereafter the mixture is subjected to a first heat treatment at 1100 to 1500 DEG C. Between 0.1 and 10 mol % of at least one of the ammonium halogenides is added to the product thus obtained per mol of the Al present and the mixture thus obtained is subsequently subjected to a second heat treatment at a temperature of 700 to 1200 DEG C.