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US 7,252,790 B2Granted
Zinc sulfide electroluminophores and method for production thereof
AssigneesLeuchtstoffwerk Breitungen GmbH, Bundesdruckerei GmbH
InventorsFrank Kappe, Benedikt Ahlers, Arnim Franz-Burgholz, Hans-Jurgen Limburg, Detlef Starick, Monika Voh
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Abstract
Zinc sulfide electroluminophores are prepared from solutions of zinc salts with hydrogen sulfide. The zinc sulfide compounds are mixed with activator and coactivator compounds to produce luminophores, and the mixtures are fired in the presence of fixing agents. These fired materials are then treated in an acid bath, washed, neutralized, and optionally filtered and dried.
Claims19
A method for producing zinc sulfide electroluminophores which have an average grain size of from 2 to 20 microns comprising:
- (a) preparing a fine-grain zinc sulfide by precipitating zinc sulfide from solutions of zinc salts and H2S;
- (b) mixing the obtained fine-grain zinc sulfide with activator and co-activator compounds to form luminophores;
- (c) firing the obtained mixtures at a temperature range of from 800 to 1000° C. in the presence of fluxing agents selected from the group consisting of fluorides, bromides, iodides, and mixtures thereof, to obtain powdery electroluminophores;
- (d) changing the morphology of the zinc sulfide by treating the powdery electroluminophores with an acid selected from the group consisting of organic acids, inorganic acids, and mixtures thereof in an acid bath while stirring.
1 more element
Dependencies are inferred from the claim text.