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:
Oct. 04, 1994
Filed:
Dec. 09, 1993
Shin-Etsu Chemical Co., Ltd., Tokyo, JP;
Abstract
An improved method is proposed for the preparation of a composite carbonate powder of lanthanum, cerium and terbium as a base material of a green-emitting phosphor for which the carbonate powder is desired to have a uniform particle size distribution and a particle configuration as close to spherical as possible. The improved method is characterized by two-step heat treatment of the carbonate slurry formed by the addition of, for example, ammonium hydrogen carbonate to a mixed aqueous solution of lanthanum, cerium and terbium nitrates each under specified conditions while the pH of the aqueous slurry is adjusted to 5.0 to 7.5 after the first step heat treatment but before the second step heat treatment.