Patent ID: 7147803

Claim:
A gelation process for the preparation of a yttrium aluminum garnet fluorescent powder with formula (Y 3-x-y Z x Eu y )Al 5 O 12 , wherein 0<x≦0.8, 0<y≦1.5, and Z is at least one rare earth metal selected from the group consisting of rare earth metals other than europium (Eu), said process comprises the steps of (1) grinding and homogeneously mixing water soluble compounds containing desired metals in ratios as those of the metals in the fluorescent powder to provide a powder mixture, (2) dissolving the powder mixture in water to form an aqueous solution, (3) adding an appropriate amount of a chelating agent into the aqueous solution to chelate the metals in the aqueous solution, (4) adjusting the pH value of the aqueous solution to equal to or greater than 7 and converting the aqueous solution into a viscous liquid thereby, (5) pyrolyzing the viscous liquid to an ash, (6) calcining the ash, and (7) sintering the calcined ash to form the fluorescent powder.