Alkaline earth metal silicate-luminescent substances and method for increasing the long-term stability of alkaline earth metal silicate-luminescent substances

Abstract

The invention relates to a method for improving the long-term stability of alkaline earth metal silicate-luminescent substances. The luminescent substance is formed in the form of grains and has the general chemical formula EA x Si y o z The basic lattice of , where x, y, z>0. Component EA consists of one or more alkaline earth metals. Activators are doped into the base lattice. In one step of the method, crystallites of the luminescent substance are heated in the reaction chamber (01). The volatile organoaluminum compound is heated, and a first carrier gas is passed through the organoaluminum compound, thereby obtaining a first carrier gas mixture comprising the volatile organoaluminum compound. In addition, water is heated, and a second carrier gas is passed through the water, whereby a second carrier gas mixture comprising the water is obtained. The first carrier gas mixture and the second carrier gas mixture are introduced into the reaction chamber (01), in which the crystallites of the alkaline earth metal silicate-luminescent substance are surrounded by the carrier gas mixture. As a result, the volatile organoaluminum compounds and water react with each other, at least predominantly forming aluminum metahydroxide, which forms a coating on the grains of the alkaline earth metal silicate-luminescent substance. The invention also relates to alkaline earth metal silicate-luminescent substances.

Description

technical field [0001] The invention firstly relates to a method for increasing the long-term stability of an alkaline earth metal silicate luminescent substance by coating the alkaline earth metal silicate luminescent substance in the form of grains. Alkaline earth metal silicate luminophores are used, for example, as conversion luminophores in white LED-based light sources. The invention also relates to alkaline earth metal silicate phosphors. Background technique [0002] Alkaline-earth metal silicate luminophores have a marked instability with respect to moisture, which has hitherto severely limited their usability in many applications. The following chemical reactions are considered to be undesirable reactions of alkaline earth metal orthosilicate-luminescent substances mainly caused by moisture: [0003] (Ba,Sr,Ca) 2 SiO 4 +2H 2 O→2(Ba,Sr,Ca)(OH) 2 +SiO2 2 [0004] Alkaline earth metal silicate-luminescent substances tend to aggregate and agglomerate during pro...

AI Technical Summary

Problems solved by technology

Therefore, in the case of reactions carried out in the presence of water, decomposition and thus loss of strength of the alkaline earth metal orthosilicate-luminescent species is expected

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