The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jan. 03, 1989
Filed:
Mar. 29, 1988
Robert J Pet, Eindhoven, NL;
Martin M van den Nieuwenhof, Eindhoven, NL;
Josephus P Duisters, Eindhoven, NL;
U.S. Philips Corporation, New York, NY (US);
Abstract
Method of preparing a luminescent Eu.sup.2+ activated strontium aluminate defined by the formula Sr.sub.4 Al.sub.14 O.sub.25 :Eu.sup.2+ in which per mol of the Al present a combination of between 0.1 and 5 mol % of B.sub.2 O.sub.3 or compounds yielding B.sub.2 O.sub.3 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 as a flux to a mixture comprising SrO, Al.sub.2 O.sub.3 and Eu.sub.2 O.sub.3 or compounds yielding these oxides upon an increase of temperature, whereafter the mixture is subjected to a first heat treatment in a weekly reducing atmosphere at 1100.degree. to 1500.degree. C. Between 0.1 and 10 mol % of at least one of the ammonium halogenides is added per mol of the Al present to the product thus obtained, and the mixture thus obtained is subsequently subjected to a second heat treatment at a temperature of 700.degree. to 1200.degree. C.