Y2O3:RE nanoparticles
The invention provides Y 2 O 3 :RE nanoparticles having a cubic crystal structure, wherein RE is a trivalent rare earth metal ion. The invention further provides a method of preparing Y 2 O 3 :RE nanoparticles, comprising: a) providing a mixture comprising (i) an yttrium salt and/or yttrium alkoxide, (ii) a rare earth metal salt and/or rare earth metal alkoxide, and (iii) an organic solvent; b) optionally, subjecting the mixture to a pre-treatment step which comprises heating the mixture at a temperature of at least 80° C. and/or at a temperature such that crystal water and/or organic impurities are removed, c) heating the mixture at a temperature between 220° C. and 320° C. and/or at a temperature such that a precursor complex forms; d) subjecting the mixture to a precipitation stage, wherein a precipitate forms, said precipitation stage preferably comprising allowing the mixture to cool and/or adding an antisolvent to the mixture; and e) heating the precipitate at a temperature between 600° C. and 900° C. and/or at a temperature such that a cubic Y 2 O 3 crystal structure forms, preferably for at least 10 minutes.
1 . A luminescent composition comprising Y 2 O 3 :RE nanoparticles having a cubic crystal structure, wherein RE is a trivalent rare earth metal ion, wherein the nanoparticles are in the form of nanoplatelets, wherein at least one dimension is ≥50 nm and ≤500 nm, and wherein the D50 value of the smallest dimension of the nanoparticles is ≥0.5 nm and ≤10 nm.
2 . The composition according to claim 1 , wherein RE is europium (III) or terbium (III) or a combination thereof.
3 . The composition according to claim 1 , wherein one dimension is ≥0.5 nm and ≤10 nm.
4 . The composition according to claim 1 , capable of emitting in the red, green and/or yellow spectral range.
5 . The luminescent composition according to claim 1 , comprising a first luminescent material capable of emitting light in a first wavelength range and a second luminescent material being capable of absorbing light in a second wavelength range, and having an emission spectrum which overlaps at least partly with one or more of the excitation bands of said first luminescent material, wherein at least one of said first luminescent material or said second luminescent material comprises the Y 2 O 3 :RE nanoparticles of claim 1 .
6 . The luminescent composition according to claim 5 , wherein the first luminescent material and second luminescent material are so arranged to each other to allow non-radiative energy transfer from the second luminescent material to the first luminescent material.
7 . The luminescent composition according to claim 1 , comprising a first luminescent material capable of emitting light in a first wavelength range and a second luminescent material being capable of absorbing light in a second wavelength range, and having an emission spectrum which overlaps at least partly with one or more of the excitation bands of said first luminescent material, wherein the first material comprises the Y 2 O 3 :RE nanoparticles of claim 1 , and the second material comprises Y 3 Al 5 O 12 (“YAG”), Lu 3 Al 5 O 12 (“LuAG”), or a combination thereof and the dopant includes Ce 3+ , Tb 3+ , or a combination of Ce 3+ and Tb 3+ .
8 . The luminescent composition according to claim 1 , comprising a first luminescent material capable of emitting light in a first wavelength range and a second luminescent material being capable of absorbing light in a second wavelength range, and having an emission spectrum which overlaps at least partly with one or more of the excitation bands of said first luminescent material, wherein the first material comprises the Y 2 O 3 :RE nanoparticles of claim 1 , and the second material comprises a semiconductor nanoparticle material.
9 . The luminescent composition according to claim 1 , comprising a first luminescent material capable of emitting light in a first wavelength range and a second luminescent material being capable of absorbing light in a second wavelength range, and having an emission spectrum which overlaps at least partly with one or more of the excitation bands of said first luminescent material, wherein the first material comprises the Y 2 O 3 :RE nanoparticles of claim 1 , wherein RE is Eu, and the second material comprises nanoparticles of Y 3 Al 5 O 12 :Ce, Lu 3 Al 5 O 12 :Ce or a combination thereof, or nanoparticles of Y 3 Al 5 O 12 :Ce,Tb, Lu 3 Al 5 O 12 :Ce,Tb or a combination thereof.
10 . The luminescent composition according to claim 1 , comprising a first luminescent material capable of emitting light in a first wavelength range and a second luminescent material being capable of absorbing light in a second wavelength range, and having an emission spectrum which overlaps at least partly with one or more of the excitation bands of said first luminescent material, wherein the first material comprises the Y 2 O 3 :RE nanoparticles of claim 1 , wherein RE is Tb, and the second material comprises nanoparticles of Y 3 Al 5 O 12 :Ce, Lu 3 Al 5 O 12 :Ce or a combination thereof, or nanoparticles of Y 3 Al 5 O 12 :Ce,Tb, Lu 3 Al 5 O 12 :Ce,Tb or a combination thereof.
11 . The luminescent composition according to claim 1 , comprising a first luminescent material capable of emitting light in a first wavelength range and a second luminescent material being capable of absorbing light in a second wavelength range, and having an emission spectrum which overlaps at least partly with one or more of the excitation bands of said first luminescent material, wherein the first material comprises the Y 2 O 3 :RE nanoparticles of claim 1 , wherein RE is Tb and Eu, and the second material comprises nanoparticles of Y 3 Al 5 O 12 :Ce, Lu 3 Al 5 O 12 :Ce or a combination thereof, or nanoparticles of Y 3 Al 5 O 12 :Ce,Tb, Lu 3 Al 5 O 12 :Ce,Tb or a combination thereof.
12 . A method of preparing Y 2 O 3 :RE nanoparticles, comprising:
a) providing a mixture comprising (i) an yttrium salt and/or yttrium alkoxide, (ii) a rare earth metal salt and/or rare earth metal alkoxide, and (iii) an organic solvent;
b) optionally, subjecting the mixture to a pre-treatment step which comprises heating the mixture at a temperature of at least 80° C. and/or at a temperature such that crystal water and/or organic impurities are removed,
c) heating the mixture at a temperature between 220° C. and 320° C. and/or at a temperature such that a precursor complex forms;
d) subjecting the mixture to a precipitation stage, wherein a precipitate forms; and
e) heating the precipitate at a temperature between 600° C. and 900° C. and/or at a temperature such that a cubic Y 2 O 3 crystal structure forms.
13 . The method according to claim 12 , wherein;
the yttrium salt is chosen from the group consisting of halides, acetates, acetylacetonates, sulfates, and nitrates, or a mixture thereof, and/or the hydrated versions thereof;
the yttrium alkoxide has the formula Y(OR) 3 , wherein RO − is the alkoxide and R is a C1-C4 group;
the rare earth metal salt is chosen from the group consisting of halides, acetates, acetylacetonates, sulfates, and nitrates, or a mixture thereof, and/or the hydrated versions thereof; and/or
the rare earth metal alkoxide has the formula RE(OR) 3 , wherein RO − is the alkoxide and R is a C1-C4 group.
14 . The method according to claim 12 , wherein the organic solvent has a boiling point of at least 280° C. at a pressure of 10 5 Pa and/or is chosen from the group of 1-octadecene, oleylamine, octadecylamine, oleic acid, or a mixture thereof.
15 . The method according to claim 12 , wherein, in stage b), the mixture is heated at least about 100° C. and at most about 180° C. under atmospheric pressure, or at least 80° C. at most about 130° C. under vacuum, and/or the mixture is heated for at least 10 minutes.
16 . The method according to claim 12 , wherein, in stage c), the mixture is heated for at least 15 minutes.
17 . The method according to claim 12 , wherein the antisolvent is a polar organic solvent.
18 . The method according to claim 12 , wherein the precipitate is heated for 10-60 minutes.
19 . The method according to claim 12 , wherein in stage c), the precipitation stage comprises allowing the mixture to cool and/or adding an antisolvent to the mixture.
20 . A composition comprising Y 2 O 3 :RE nanoparticles obtained by the method according to claim 12 , wherein said Y 2 O 3 :RE nanoparticles have a cubic crystal structure, wherein RE is a trivalent rare earth metal, wherein the nanoparticles are in the form of nanoplatelets, wherein at least one dimension is ≥50 nm and ≤500 nm, and wherein the D50 value of the smallest dimension of the nanoparticles is ≥0.5 nm and ≤10 nm.