Annealing method

The method according to any preceding claim, wherein said first luminescent material or said precursor thereof and/or said second luminescent material or said precursor thereof are in the form of nanoparticles, preferably wherein said first luminescent material or said precursor thereof and said second luminescent material or said precursor thereof are in the form of nanoparticles, preferably wherein the D50 value of the nanoparticles is ≥1 nm and ≤100 nm.

The method according to any preceding claim, wherein said first luminescent material or said precursor thereof is doped with one or more ions selected from the group consisting of Eu3+, Tb3+, and Mn4+.

The method according to any preceding claim, wherein said first luminescent material is a red emitting material. The method according to any preceding claim, wherein said second luminescent material is excitable in the wavelength range between 380 to 580 nm, preferably wherein said second luminescent material is excitable in the high UV-A (380 to 400 nm), violet (400 to 440 nm), blue (440 to 480 nm) or green (510 to 560 nm) wavelength range, preferably in the blue (440 to 480 nm) wavelength range.

The method according to any preceding claim, wherein said second luminescent material or said precursor thereof is doped with one or more ions selected from the group consisting of Eu2+, Pb2+, Bi3+ and Ce3+, preferably Ce3+.

The method according to any preceding claim, wherein said second luminescent material or said precursor thereof has a host lattice which is Y3Al5O12 (“YAG”) or Lu3Al5O12 (“LuAG”) or a combination thereof, preferably wherein said second luminescent material or said precursor thereof is doped with Ce3+.

The method according to any preceding claim, wherein the ratio of salt to luminescent material in said mixture is more than 1:1 (w/w), preferably more than 2:1 (w/w), more preferably more than 5:1 (w/w), most preferably more than 10:1 (w/w).

A method for treating or obtaining a luminescent material, said method comprising:

• (I) preparing a mixture comprising (i) a luminescent material and/or a precursor thereof and (ii) a salt, and
• (II) heating the mixture at a temperature of 300° C. or more,
• wherein the ratio of salt to luminescent material and/or precursor thereof in the mixture is more than 1:1 (w/w), preferably more than 2:1 (w/w), more preferably more than 5:1 (w/w), most preferably more than 10:1 (w/w).

The method according to any of the preceding claims, wherein the salt comprises Se2−, S2−, Cl−, F−, Br−, I−, SO42−, PO43−, or NO3−, or a combination thereof as anion and H+, Li+, Na+, Al3+, Ba2+, K+, Be2+, Ca2+, Mg2+, or Sr2+, or a combination thereof as cation.

The method according to any of the preceding claims, wherein the salt is K2SO4, and the, for instance second, luminescent material has a host lattice which is YAG or LuAG, or a combination thereof.

The method according to any preceding claim, wherein the method further comprises comminuting the salt, for instance by milling or grinding.

The method according to any preceding claim, wherein the mixture comprising (i) said luminescent material or said precursor thereof and (ii) said salt is subjected to ultrasonic, milling and/or grinding.

The method according to any preceding claim, wherein the luminescent material comprises organic ligands, and wherein said ligands are selected such as to enhance mixing with the salt.

The method according to any preceding claim, wherein said heating comprises heating said mixture at a temperature of 900 to 1500° C., preferably for 1 minute to 20 h.

The method according to any preceding claims, wherein the method comprises, after said heating, removing said salt (from the mixture) by contacting the liquid with a solvent, for instance water.

The method according to any preceding claim, wherein organic ligands are removed from the luminescent material.

The method according to any preceding claim, wherein said luminescent material or precursor thereof (e.g. said first luminescent material or said precursor thereof and/or said second luminescent material or said precursor thereof) is crystalline prior to said heating.

The method according to any preceding claim, wherein said luminescent material or precursor is not-crystalline and/or may not contain all elements of the final product material prior to said heating.

Luminescent composition obtainable by the method according to any preceding claim.

Luminescent material obtainable by the method according to any preceding claim.