Methods for preparation of nanocrystalline rare earth phosphates for lighting applications
AssigneeGeneral Electric Company
InventorsHolly Ann Comanzo, Mohan Manoharan, Sergio Paulo Martins Loureiro, Anant Achyut Setlur, Alok Mani Srivastava
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Abstract
Disclosed here are methods for the preparation of optionally activated nanocrystalline rare earth phosphates. The optionally activated nanocrystalline rare earth phosphates may be used as one or more of quantum-splitting phosphor, visible-light emitting phosphor, vacuum-UV absorbing phosphor, and UV-emitting phosphor. Also disclosed herein are discharge lamps comprising the optionally activated nanocrystalline rare earth phosphates provided by these methods.
Claims20
A method for the preparation of a nanocrystalline rare earth phosphate, the method comprising:
- combining in an aqueous medium
- a phosphate source including a partially neutralized phosphoric acid,
- (ii) at least one water soluble salt of a primary rare earth selected from the group consisting of La, Lu, Y, Gd, and optionally
- (iii) at least one water soluble salt of an activator element selected from the group consisting of Pr, Nd, Eu, Ce, Tb, Bi, and Pb;
- wherein said combining is effective to form a precipitate comprising at least phosphate and the primary rare earth;
- and
- calcining the precipitate under conditions including temperature less than about 400° C. to form a nanocrystalline rare earth phosphate.
A discharge lamp comprising a discharge source, a fill gas, and an envelope, where an inner surface of said envelope is coated with a phosphor composition comprising the nanocrystalline rare earth phosphate in accordance with claim 17.
A method for the preparation of a nanocrystalline activated lanthanum phosphate, the method comprising:
- combining in an aqueous medium
- (i) a phosphate source including a dibasic phosphate,
- (ii) a water soluble lanthanum salt, and
- (iii) at least one water soluble salt of an activator element selected from the group consisting of Pr, Nd, Eu, Ce, Tb, Bi, and Pb;
- wherein said combining is effective to form a precipitate comprising phosphate, lanthanum, and at least one said activator element;
- and
- calcining the precipitate under conditions including temperature of from about 300° C. to less than about 400° C. under an oxidizing or weakly reducing atmosphere to form a nanocrystalline activated lanthanum phosphate having an average primary crystallite size of from about 1 nm to about 100 nm.
Dependencies are inferred from the claim text.