Microjet reactor-based synthesis of nanophosphors

Abstract

A method for producing luminescent nanoparticles of the A2-xO3:Lnx type [wherein A is one or more of yttrium, scandium, aluminum, gallium, or lanthanide; Ln is at least one lanthanide; and 0 < x < 2], the method comprising: preparing a first mixture containing at least a salt of A, a salt of Ln, and a solvent; preparing a second mixture containing a precipitating agent and a solvent; contacting the first mixture and the second mixture in a microjet reactor to obtain a third mixture containing nanoparticles; and heating the nanoparticles. A composition containing the nanoparticles obtained by this method and its applications are also provided.

Description

[Technical field]

[0001] The present invention provides methods for synthesizing nanophosphor materials using a microjet reactor, and compositions including nanophosphors synthesized using a microjet reactor. [Background technology]

[0002] Luminescent down-conversion materials or phosphors play an important role in solid-state lighting devices, especially for illumination and display applications. For some applications, it is desirable for these phosphors to have particle sizes in the nano-regime.

[0003] Microjet reactors are suitable devices for the production of nanomaterials and include all geometries described in EP 1165224 (B1) and DE 102009008478 (AI).

[0004] WO 2011 / 116763 and US Pat. No. 9,901,893 B2 disclose methods for obtaining nanoparticles using a microjet reactor, but these methods are aimed at pharmaceutical particles, which are generally organic materials.

[0005] US Patent Application Publication No. 2010 / 019201 A1 discloses a method for obtaining nanoparticles using a hydrothermal method, which requires high temperature and pressure.

[0006] Inorganics 2014, 2, 1-15; doi:10.3390 / inorganics2010001 describes the synthesis of various inorganic oxide materials using a precipitation method with a microjet reactor.

[0007] Ceramic Applications 4 (2016) [2] and Keram.Z. 69 (2017) [6] disclose the synthesis of luminescent YVO4:RE and YAG materials. However, the final materials were not nano-sized.

[0008] International Publication No. 2018 / 167266 discloses a composition comprising a luminescent material and a sensitizer material, wherein the luminescent material and the sensitizer material are selected such that the sensitizer material has an emission spectrum that at least partially overlaps with one or more excitation bands of the luminescent material, and the luminescent material and the sensitizer material are arranged relative to each other such that non-radiative energy transfer from the sensitizer material to the luminescent material is enabled.

[0009] Non-radiative energy transfer from the sensitizer material to the luminescent material (also referred to as fluorescence resonance energy transfer, FRET) involves non-radiative transfer of energy from an excited sensitizer ion in the sensitizer material to a receptor (or emitter) ion in the luminescent material. This is evidenced by an increase in the emission from the emitter ions in the luminescent material when the sensitizer ions in the sensitizer material are selectively excited.

[0010] Nanomaterials are of interest due to their large surface area and small volume, which enable the placement of luminescent materials in close proximity in space and the utilization of inter-particle FRET.

[0011] A method for producing luminescent nanomaterials on a large scale in a reproducible manner is desired. SUMMARY OF THE INVENTION

[0012] According to the present invention, a method for producing luminescent nanoparticles of the formula A 2-x O3:Ln x [wherein A is one or more of yttrium, scandium, gallium, aluminum or lanthanide; Ln is at least one lanthanide; and 0 < x < 2], comprising: - preparing a first mixture comprising at least a salt of A, a salt of Ln and a solvent; - Preparing a second mixture comprising a precipitating agent and a solvent; - Contacting the first mixture and the second mixture in a microjet reactor to obtain a third mixture containing nanoparticles; and - Heating the nanoparticles A method is provided which includes the above steps.

[0013] According to the present invention, nanoparticles obtained by the method of the present invention are provided.

[0014] According to the present invention, a luminescent composition is provided, which comprises a first luminescent material capable of emitting light of a first wavelength and a second luminescent material capable of absorbing light of a second wavelength and having an emission spectrum that at least partially overlaps with one or more of the excitation bands of the first luminescent material, wherein at least one of the first luminescent material or the second luminescent material contains the nanoparticles according to the present invention.

[0015] By the method of the present invention, highly crystalline luminescent nanoparticles can be obtained in an efficient and reproducible manner. By this method, nanoparticles with a high quantum yield can be obtained.

[0016] The nanoparticles of the present invention exhibit good light absorption / emission properties and are suitable for mixing into luminescent compositions. They have few crystal defects, are small in size and highly crystalline. They can be advantageously used in compositions where non-radiative energy transfer (also called fluorescence resonance energy transfer, FRET) is desired. Detailed Description of the Invention

[0017] Nanoparticles The nanoparticles according to the present invention are of the A 2-x O3:Ln x type [wherein A is one or more of yttrium, scandium, aluminum, gallium or lanthanide; Ln is at least one lanthanide; and 0 < x < 2] of luminescent nanoparticles.

[0018] The annotation ":Ln" means that the material is doped with Ln. The doping ions are present at the sites where A is present.

[0019] A may be a lanthanide, and Ln is at least one lanthanide. The lanthanide or at least one lanthanide is selected from the lanthanide series, i.e., elements with atomic numbers 57 to 71. Preferably, when A comprises a lanthanide, the lanthanide is selected from the group of lutetium or gadolinium. Preferably, Ln is at least one of europium, terbium or cerium in the trivalent oxidation state. Eu 3+ When suitably excited, Ce emits red light. 3+ is Y3Al5O 12 When embedded in a suitable garnet host lattice such as (YAG), it exhibits strong blue absorption and a broad yellow-green emission band when suitably excited. 3+ When suitably excited, it emits yellow to green light.

[0020] Preferably, the doping concentration is at least 10% for europium doped nanoparticles, more preferably the doping concentration is between 15% and 80%. As used herein, the doping concentration is the percentage of doping ions relative to the sum of doping ions and A atoms in the crystal lattice.

[0021] Preferably, the doping concentration is at least 0.1% for cerium doped nanoparticles, more preferably the doping concentration is 1-3%.

[0022] Preferably, the doping concentration is at least 15% for terbium doped nanoparticles, more preferably the doping concentration is between 20% and 80%.

[0023] Preferably, for europium and terbium co-doped nanoparticles, the doping concentration of europium is between 15% and 50%, and the doping concentration of terbium is at least 15%.

[0024] Preferably, for cerium and terbium co-doped nanoparticles, the doping concentration of cerium is between 0.1% and 3%, and the doping concentration of terbium is at least 15%.

[0025] In a preferred embodiment, A contains yttrium. This form is also known as Y2O3:Ln, i.e., yttrium oxide.

[0026] In a preferred embodiment, A contains scandium. This form is also known as Sc2O3:Ln, or scandium oxide.

[0027] In a preferred embodiment, A contains aluminum. This form is also known as Al2O3:Ln, i.e. aluminum oxide.

[0028] In a preferred embodiment, A contains gallium. This form is also known as Ga2O3:Ln, i.e., gallium oxide.

[0029] In a preferred embodiment, A contains lutetium. This form is also known as Lu2O3:Ln, i.e., lutetium oxide.

[0030] In a preferred embodiment, A contains gadolinium. This form is also known as Gd2O3:Ln, or gadolinium oxide.

[0031] Preferably, the nanoparticles of the present invention are 12 :Ln type [wherein A1 is one or more selected from the group consisting of yttrium, lutetium, and gadolinium; A2 is one or more selected from the group consisting of aluminum, gallium, and scandium; and Ln is at least one lanthanide].

[0032] Thus, the nanoparticles of the present invention are YAlO 12 :Ln(YAG:Ln), Lu3Al5O 12:Ln(LuAG:Ln), (Y x ,Lu (1-x) )3AlO 12 :Ln((Lu,Y)AG:Ln), (Y x ,Lu (1-x) )3(Al 1-y Ga y )5O 12 :Ln, (Y x ,Lu (1-x) )3(Al 1-y Sc y )5O 12 :Ln, (Y x ,Lu (1-x) )3(Sc 1-y Ga y )5O 12 :Ln, (Y x ,Gd (1-x) )3(Al 1-y Ga y )5O 12 :Ln, (Y x ,Gd (1-x) )3(Al 1-y Sc y )5O 12 :Ln, (Y x ,Gd (1-x) )3(Sc 1-y Ga y )5O 12 :Ln, (Lu x ,Gd (1-x) )3(Al 1-y Ga y )5O 12 :Ln, (Lu x ,Gd (1-x) )3(Al 1-y Sc y )5O 12 :Ln or (Lu x ,Gd (1-x) )3(Sc 1-y Ga y )5O 12 :Ln wherein Ln is at least one lanthanide as previously defined and 0≦x≦1 and 0≦y≦1.

[0033] Nanoparticles according to the invention include particles having at least one dimension on the nanometer scale, preferably 100 nm or less, as measured using a transmission electron microscope (TEM), a high-resolution scanning electron microscope (HR-SEM), a scanning transmission electron microscope (STEM) or an atomic force microscope (AFM). 50 is defined as the median value of the smallest dimension of the nanoparticles measured from a population of at least 50 representative particles. Preferably, the nanoparticles have a D of 10 nm or less. 50 It has a value.

[0034] Nanoparticles are D of 1 nm or more. 50 Preferably, the nanoparticles have a D value of 2 nm or more. 50 It has a value.

[0035] Preferably, the nanoparticles according to the invention are capable of luminescence.

[0036] Preferably, the Ln-doped nanoparticles according to the present invention can emit in the red and / or green spectrum. As used herein, the term red emitting material refers to a material that has one or more emission bands between 600 nm and 700 nm upon suitable excitation. As used herein, the term green emitting material refers to a material that has one or more emission bands between 510 nm and 560 nm upon suitable excitation.

[0037] Manufacturing method The present invention provides a method for producing luminescent rare earth doped nanoparticles using a microjet reactor.

[0038] The method according to the invention makes it possible to obtain nanoparticles according to the invention.

[0039] Step a) Providing a first mixture comprising at least a salt of A, a salt of Ln, and a solvent. A first mixture is prepared that includes at least a salt of A, a salt of Ln, and a solvent.

[0040] A is one or more of yttrium, scandium, gallium, aluminum or a lanthanide; Ln is at least one lanthanide; <x<2である。

[0041] Preferably, the salt of A is selected from the group consisting of the halide salts, acetate salts, acetylacetonate salts, sulfate salts, nitrate salts and / or hydrated forms of these substances.

[0042] When A comprises yttrium, the yttrium salt is preferably selected from the nitrate, acetate or hydrated forms thereof.

[0043] When A comprises a lanthanide, the lanthanide salt is preferably selected from acetate or a hydrated form thereof.

[0044] In some embodiments, mixtures of yttrium, lutetium and / or gadolinium salts may be used. Such mixtures provide a 12 It is possible to obtain nanoparticles of the Ln type, in which A1 is one or more selected from the group consisting of yttrium, lutetium and gadolinium; A2 is one or more selected from the group consisting of aluminum, gallium and scandium; and Ln is at least one lanthanide.

[0045] One skilled in the art can determine the relative amounts of salts to achieve the desired ratio of ions in the nanoparticles. 12 A1 (one or more selected from the group of yttrium, lutetium, and gadolinium) to A2 (one or more selected from the group of aluminum, gallium, and scandium) can be determined to obtain a :Ln ratio. A person skilled in the art can also determine the amount of Ln relative to A1 (one or more selected from the group of yttrium, lutetium, and gadolinium) to obtain a desired doping concentration. The stoichiometric A13A25O 12 In :Ln garnet, the ratio of (A1+Ln):(A2) is 3:5.

[0046] In one embodiment, a mixture of yttrium and lutetium salts is used, which allows obtaining yttrium lutetium aluminum garnet ((Y,Lu)AG) type nanoparticles.

[0047] Those skilled in the art can determine the relative amounts of salts to obtain the desired ratio of ions in the nanoparticles. Thus, those skilled in the art can determine the amount of yttrium and / or lutetium relative to aluminum to obtain the desired YAG:Ln or LuAG:Ln ratio. Those skilled in the art can also determine the amount of rare earth relative to yttrium and / or lutetium to obtain the desired doping concentration. In stoichiometric aluminum garnet, the ratio of (Ln+yttrium+lutetium):Al is 3:5.

[0048] When A is one or more of aluminum, scandium or gallium, the salt is selected from the group consisting of halide salts, acetate salts, acetylacetonate salts, sulfate salts, nitrate salts and / or hydrated forms of these materials.

[0049] More preferably, when A comprises aluminum, aluminum nitrate is used.

[0050] Preferably, at least some of the aluminum salts are replaced by gallium salts and / or scandium salts. This may result in gallium and / or scandium substitution at least some of the aluminum sites in the garnet lattice, which can result in a shift in the excitation / emission spectrum. Thus, the replacement of aluminum salts by gallium salts and / or scandium salts can be used to tune the excitation / emission spectrum of the product.

[0051] In some embodiments, a mixture of aluminum, gallium and / or scandium may be used, thereby forming A13A25O 12Nanoparticles of the Ln type can be obtained, in which A1 is one or more selected from the group consisting of yttrium, lutetium and gadolinium; A2 is one or more selected from the group consisting of aluminum, gallium and scandium; and Ln is at least one lanthanide.

[0052] Preferably, the Ln salt is selected from the group consisting of halide salts, acetate salts, acetylacetonate salts, sulfate salts, nitrate salts and / or hydrated forms of these substances. More preferably, Ln is selected from acetate salts or hydrated forms thereof.

[0053] Preferably, Ln is europium, cerium and / or terbium. 3+ When suitably excited, Tb emits yellow to green light. 3+ Eu emits green light when suitably excited. 3+ exhibits red emission when suitably excited. More preferably, Ln is a combination of cerium and terbium or a combination of europium and terbium.

[0054] Ln is present as a dopant. Preferably, the doping concentration is between 0.01% and 3% for cerium-doped nanoparticles, more preferably the doping concentration is 2.5%. As used herein, the doping concentration is the percentage of doping ions relative to the sum of doping ions and yttrium or lutetium atoms in the crystal lattice.

[0055] Preferably, for cerium and terbium co-doped nanoparticles, the doping concentration of cerium is from about 0.01% to about 2.5%, and the doping concentration of terbium is at least about 30%.

[0056] Preferably, the doping concentration is at least 10% for europium doped nanoparticles, more preferably the doping concentration is between 15% and 80%.

[0057] Preferably, for europium and terbium co-doped nanoparticles, the doping concentration of europium is from about 15% to about 50%, and the doping concentration of terbium is at least about 15%.

[0058] Preferably, the Ln salt is present in the mixture such that the desired doping concentration is achieved.

[0059] Preferably, the pH of the first mixture is such that the metal salt dissolves in the solvent without precipitating, and more preferably, the pH of the first mixture is 4 to 5.

[0060] The first mixture preferably comprises an acid or a base. More preferably, the first mixture comprises an acid. The acid can be selected from HCl or HNO3. The base can be selected from NH3, NaOH, KOH, NH4HCO3 or CH4N2O.

[0061] The mixture comprises a solvent, which is preferably a polar solvent, more preferably selected from the group of water or short chain alcohols.

[0062] Step b) providing a second mixture comprising a precipitant and a solvent. The second mixture includes a precipitant and a solvent.

[0063] The precipitating agent is preferably a base, more preferably the precipitating agent is urea or ammonium bicarbonate.

[0064] Preferably, the second mixture contains the precipitant ammonium bicarbonate in a concentration of 1M to 2M.

[0065] The pH of the second mixture is preferably greater than 7. The pH can be adjusted using the same base or a different base. Preferably, the pH is adjusted using ammonia (NH3).

[0066] It has been found that the pH of the second mixture can be adjusted depending on the desired crystal lattice type.

[0067] In a preferred embodiment, the nanoparticles are of the Y2O3:Ln, Sc2O3:Ln, Lu2O3:Ln or Gd2O3:Ln type and the pH of the second mixture is 8 or higher.

[0068] In a preferred embodiment, the nanoparticles are 12 :Ln type [wherein A1 is one or more selected from the group consisting of yttrium, lutetium and gadolinium; A2 is one or more selected from the group consisting of aluminum, gallium and scandium; and Ln is at least one lanthanide], and the pH of the second mixture is 7 to 8.

[0069] Step c) contacting the first mixture with the second mixture in a microjet reactor to obtain a third mixture comprising nanoparticles. The first mixture and the second mixture are contacted in a microjet reactor to obtain a third mixture comprising nanoparticles.

[0070] Microjet reactors are suitable devices for the production of nanomaterials and include all the shapes described in EP 1165224 B1 and DE 102009008478 A1. Preferably, a microjet reactor of the type described in EP 1165224 B1 is used, which operates without the use of gas. Mixing in conventional microreactors, for example developed as T-mixers, takes a substantially long time, since these reactors customarily operate in the laminar flow range. To carry out the method of the invention, the microjet reactor may be designed so that the liquid jets collide at angles other than 180° or the jets mix at a common impingement surface. In these cases, the size and shape of the particles may be different.

[0071] The first mixture and the second mixture are fed into a microjet reactor, preferably at substantially the same flow rates for the two solutions.

[0072] Preferably, the first and second mixtures are fed separately to the microjet reactor, which avoids premature precipitation.

[0073] Preferably, the microjet reactor has a nozzle size of 200-300 μm, which provides the correct impingement velocity and pressure of the jet.

[0074] Preferably, the first and second mixtures are fed to the microjet reactor at a pump pressure of about 50 bar, so that the jet has an appropriate flow rate to obtain nanosized particles. The flow rate may be adjusted by adjusting the pump pressure.

[0075] Preferably, the contact is carried out at a temperature below 50° C. More preferably, the contact is carried out at room temperature or at a temperature between 15° C. and 30° C.

[0076] Preferably, the contacting is carried out at less than 5 bar, more preferably at atmospheric pressure or at 0.5 to 5 bar.

[0077] More preferably, the contacting occurs at ambient conditions.

[0078] A third mixture is obtained in step c. The third mixture comprises precipitated nanoparticles.

[0079] The pH of the third mixture is preferably 6-11.

[0080] In a preferred embodiment, the nanoparticles are of the Y2O3:Ln, Sc2O3:Ln, Lu2O3:Ln or Gd2O3:Ln type and the pH of the third mixture is 7.5-11, more preferably 8-10.

[0081] In a preferred embodiment, the nanoparticles are 12:Ln type [wherein A1 is one or more selected from the group consisting of yttrium, lutetium and gadolinium; A2 is one or more selected from the group consisting of aluminum, gallium and scandium; and Ln is at least one lanthanide], and the pH of the third mixture is 6 to 9, more preferably 7 to 7.5.

[0082] The pH of the third mixture may be adjusted with a suitable base or acid, for example, using a solution of HNO3 in water.

[0083] After precipitation, the precipitate may be separated by means known in the art, such as settling, centrifugation, filtration, and the like.

[0084] The separated precipitate is preferably washed. Washing can remove ions. If nitrates are used, washing is preferably performed to prevent the formation of explosive ammonium nitrate.

[0085] Preferably, the separated precipitate is dried, preferably by freeze-drying, which allows the desired temperature to be reached in step d) more quickly and in a more controlled manner.

[0086] Step d) Heating the nanoparticles The nanoparticles obtained in step c are subjected to a heating step.

[0087] The heating step can cause the precipitate to crystallize or improve the crystallinity.

[0088] Preferably, the heating reduces the D 50 value and 100 nm or less, more preferably 20 nm or less 50 The method includes heating a particle having a value.

[0089] Preferably, said heating comprises heating the nanoparticles at 200°C or higher; 200-1500°C or 500-1600°C, preferably 300-1200°C or 500-1300°C, preferably at least 500°C.

[0090] Preferably, the heating is carried out for at least 30 seconds, more preferably at least 1 minute, more preferably from 1.5 minutes to 3 hours.

[0091] Heating can be carried out, for example, under air or under an inert gas such as, for example, N2 or argon.

[0092] In a preferred embodiment, the heating step comprises heating a mixture comprising the nanoparticles and a protective matrix. The protective matrix may be a salt. Preferably, the nanoparticles are 12 :Ln type [wherein A1 is one or more selected from the group consisting of yttrium, lutetium and gadolinium; A2 is one or more selected from the group consisting of aluminum, gallium and scandium; and Ln is at least one lanthanide].

[0093] The mixture can be prepared according to WO 2021 / 043762.

[0094] Preferably, the mixture comprises: - dry mixing the nanoparticles with a protective matrix; - mixing the nanoparticles and the protective matrix in a liquid to obtain a dispersion, and preferably separating the liquid from the dispersion; and / or - preparing an emulsion comprising a dispersed phase comprising the nanoparticles and a protective matrix and a continuous phase, and preferably demulsifying said emulsion and separating liquid from said demulsified emulsion. Manufactured by.

[0095] Luminescent Composition Further provided are luminescent compositions comprising nanoparticles obtainable by the method of the invention or nanoparticles of the invention.

[0096] Preferably, the luminescent composition comprises a first luminescent material and a second luminescent material, and at least one of the first luminescent material or the second luminescent material comprises nanoparticles according to the invention or obtainable by the method of the invention.

[0097] Preferably, the luminescent composition comprises a first luminescent material capable of emitting light at a first wavelength and a second luminescent material capable of absorbing light at a second wavelength and having an emission spectrum at least partially overlapping 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 nanoparticles according to the invention or obtainable by the method of the invention.

[0098] Preferably, the first luminescent material and the second luminescent material are arranged relative to one another such that non-radiative energy transfer is possible from the second luminescent material to the first luminescent material.

[0099] The first luminescent material can emit light at a first wavelength. Those skilled in the art will understand that in the luminescent composition according to the present invention, the first luminescent material functions as a light-emitting material. The first wavelength can be any wavelength range of interest. Preferred wavelengths are described below.

[0100] The second luminescent material can absorb light at a second wavelength. Those skilled in the art will understand that in the luminescent composition according to the present invention, the second luminescent material functions as a sensitizer material. The second wavelength can be any wavelength range of interest. Preferred wavelengths are described below.

[0101] The second luminescent material has an emission spectrum that at least partially overlaps with one or more excitation bands of the first luminescent material when excited by light of a second wavelength. A person skilled in the art can satisfactorily determine the spectral overlap by determining the spectrum based on spectra known in the art or by routine experimentation, for example as disclosed in WO2020 / 053429.

[0102] Preferably, the overlap between the emission spectrum of the second material and one or more excitation bands of the first material is in the blue (440-480 nm), green (510-560 nm) or yellow (560-580 nm) wavelengths.

[0103] Preferably, the first luminescent material and the second luminescent material are positioned relative to each other such that non-radiative energy transfer (also called fluorescence resonance energy transfer, FRET) is possible from the second luminescent material (sensitizer material) to the first luminescent material (emitter material). Typically, this involves close proximity between the first luminescent material and the second luminescent material, for example at a distance of about 0.5 nm to about 20 nm. The skilled artisan is well aware of how non-radiative energy transfer may be achieved. This is described, for example, in WO 2018 / 167266, the contents of which are incorporated herein by reference. The skilled artisan will appreciate that non-radiative energy transfer involves the non-radiative transfer of energy from an excited sensitizer material to an acceptor (or emitter) ion in the emitter material. This is evidenced by the increased emission from the emitter ion in the emitter material upon increasing selective excitation of the sensitizer material. The non-radiative energy transfer of interest may result from either Foerster-type or Dexter-type energy transfer. Because resonance energy transfer is inversely proportional to the sixth power of the inter-ion distance (in Foerster-type energy transfer) or exponentially proportional to the distance (in Dexter-type energy transfer), those skilled in the art recognize that the configuration that allows non-radiative energy transfer can be influenced by appropriate design of the effective distance between the sensitizer material and the emitter ion in the luminescent material.

[0104] Preferably, the first luminescent material and / or the second luminescent material is A 2-x O3:Ln xType [wherein A is one or more of yttrium, scandium, gallium, aluminum or lanthanide; Ln is at least one kind of lanthanide; 0 < x < 2] comprising luminescent nanoparticles. Thereby, the interaction surface between the first and second materials is increased, and (further) non-radiative energy transfer can occur. The luminescent nanoparticles have desirable luminescent properties. Examples of luminescent nanoparticles suitable for the first luminescent material and / or the second luminescent material are YAG:Ln nanoparticles, LuAG:Ln nanoparticles, Y2O3:Ln nanoparticles, and / or other luminescent nanoparticles obtained by the method of the present invention.

[0105] Preferably, the first luminescent material comprises the luminescent nanoparticles of the present invention, and Ln is europium, or europium and terbium. These ions have the desired absorption / emission properties. More preferably, the first luminescent material comprises the nanoparticles of the present invention of the type Y2O3:Ln, Sc2O3:Ln, Lu2O3:Ln or Gd2O3:Ln; and / or the first luminescent material is A13A25O 12 :Ln type [wherein A1 is one or more selected from the group consisting of yttrium, lutetium and gadolinium, and A2 is one or more selected from the group consisting of aluminum, gallium and scandium] of the nanoparticles of the present invention. Even more preferably, the first luminescent material comprises the Y2O3:Ln nanoparticles of the present invention [wherein Ln is europium, or europium and terbium].

[0106] Preferably, the second luminescent material comprises the luminescent nanoparticles according to the present invention. The luminescent nanoparticles according to the present invention are well-suited for use in luminescent compositions. More preferably, Ln is cerium, or cerium and terbium. These ions have the desired absorption / emission properties. More preferably, the second luminescent material is A13A25O 12More preferably, the second luminescent material comprises (Lu,Y)3AlO 3 :Ln nanoparticles, where A1 is one or more selected from the group of yttrium, lutetium and gadolinium, A2 is one or more selected from the group of aluminum, gallium and scandium, and Ln is cerium, or cerium and terbium. 15 The nanoparticles include those of the present invention of the type: Ln, where Ln is cerium, or cerium and terbium.

[0107] Preferably, the first luminescent material and the second luminescent material are in the form of nanoparticles. Suitable nanoparticles include particles with at least one dimension on the nanometer scale, preferably 100 nm or less. The small size allows for a smaller distance between the surfaces of the first and second materials, which can (further) allow interparticle non-radiative energy transfer to occur. Providing the two materials in the form of nanoparticles allows for more efficient particle mixing and uniform distribution of the particles, which further facilitates the occurrence of interparticle non-radiative energy transfer.

[0108] As discussed, the minimum dimension of the nanoparticles, D 50 The value is preferably 1 nm or more and 100 nm or less, more preferably 1 nm or more and 50 nm or less, and most preferably 2 nm or more and 20 nm or less, as measured using a transmission electron microscope (TEM), a high-resolution scanning electron microscope (HR-SEM), a scanning transmission electron microscope (STEM) or an atomic force microscope (AFM). 50 is defined as the median value of the smallest dimension of the nanoparticles measured from a population of at least 50 representative particles.

[0109] In another preferred embodiment, the first luminescent material is provided as a bulk material and the second luminescent material is provided on the first luminescent material, where the term "bulk" as used herein means and / or includes, among other things, larger than the nanoscale, e.g., greater than 100 nm in diameter, and also includes the micro-size scale.

[0110] One skilled in the art will understand that for FRET to occur, the first and second materials must be in close proximity. Nanoparticles according to the present invention may be processed as described in WO2020 / 053429 and / or WO2021 / 043762, both of which are incorporated herein by reference.

[0111] First Luminescent Material As discussed, the second luminescent material may include nanoparticles according to the present invention.

[0112] In a preferred embodiment, the second luminescent material comprises nanoparticles according to the invention and the first luminescent material comprises nanoparticles according to the invention. Preferably, the first luminescent material comprises luminescent nanoparticles according to the invention, where Ln is europium, terbium, or europium and terbium. These ions have the desired absorption / emission properties. More preferably, the first luminescent material comprises nanoparticles according to the invention of the Y2O3:Ln, Sc2O3:Ln, Lu2O3:Ln or Gd2O3:Ln type; and / or the first luminescent material comprises nanoparticles according to the invention of the A13A25O 12 More preferably, the first luminescent material comprises nanoparticles of the present invention of the Y2O3:Ln type, where A1 is one or more selected from the group of yttrium, lutetium and gadolinium, and A2 is one or more selected from the group of aluminum, gallium and scandium. Even more preferably, the first luminescent material comprises nanoparticles of the present invention of the Y2O3:Ln type, where Ln is europium or europium and terbium.

[0113] In a preferred embodiment, the second luminescent material comprises nanoparticles according to the present invention and the first luminescent material is preferably as described below.

[0114] The first luminescent material is capable of emitting light at a first wavelength, which may be in any wavelength range of interest.

[0115] Preferably, the first luminescent material comprises a red or green luminescent material. As used herein, the term red luminescent material refers to a material having one or more emission bands between 600 nm and 700 nm upon suitable excitation, and the term green luminescent material refers to a material having one or more emission bands between 510 and 560 nm upon suitable excitation. Providing a red or green luminescent material may be desirable for color-imparting purposes. According to another aspect of the invention, the first luminescent material is a material having one or more emission bands between 700 and 1400 nm (IR-A), 580 and 600 nm (amber and / or orange), 560 and 580 nm (yellow), 480 and 510 nm (cyan), 440 and 480 nm (blue), 400 and 440 nm (violet), 315 and 400 nm (UV-A) and / or 280 and 315 nm (UV-B) upon suitable excitation.

[0116] In a preferred embodiment, the first luminescent material comprises a rare earth doped phosphor material. The phosphor material may be a divalent or trivalent rare earth doped phosphor. Examples of suitable rare earth doped phosphor materials include, but are not limited to, LaPO4:Eu 3+ (and / or Tb 3+ ), CaAlSiN3:Eu 2+ , Y2O3:Eu 3+ (and / or Tb 3+ ), Y(V,P)O4:Eu 3+ (and / or Tb 3+ ), Lu3Al5O 12 :Ce 3+( or EU 3+ and / or Tb 3+ ), Y3Al5O 12 :Ce 3+(or EU 3+ and / or Tb 3+ ), BaMgAl 14 O 23 :Mn 2+ , Mg(Al,Ga)2O4:Mn 2+ , Zn2SiO4:Mn 2+ , K2SiF6:Mn 4+ , MgF2.GeO2:Mn 4+ , as well as combinations thereof.

[0117] Phosphor materials may be obtained today on the open market or may be synthesized, for example, as described in Riwotzki, K.; Meyssamy, H.; Kornowski, A.; Haase, MJ Phys. Chem. B. 2000, 104, 2824-2828, or according to the methods of the present invention.

[0118] As known to those skilled in the art, rare earth doped phosphor materials include a host lattice doped with optically active ions.

[0119] The first luminescent material may have a suitable host lattice, which may be selected from the group consisting of, for example, oxides, fluorides, nitrides, borates, garnets, molybdates, phosphates, vanadates, chlorides, sulfides, selenides, silicates, aluminates, oxyfluorides, oxychlorides, oxynitrides, oxysulfides, oxyselenides, fluorochlorides, fluorosilicates and fluorobromides, or combinations thereof, or another inorganic host material capable of incorporating optically active ions.

[0120] Preferably, the host lattice of the first luminescent material is an oxide, phosphate, vanadate or combination thereof, more preferably YAlO 12 (YAG), Lu3Al5O 12 (LuAG), Y2O3, YVPO4, YVO4 or LaPO4, or combinations thereof. Preferably, the preferred host lattice of the first luminescent material is selected from the group consisting of Eu3+ , Tb 3+ , Mn 2+ and Mn 4+ These ions provide strong and / or good luminescence properties, such as emission bands in the red or green portion of the visible spectrum.

[0121] EU 3+ In the case of doping, the first luminescent material may have a doped host lattice, for example having a doping concentration of at least about 10%, more preferably from about 15% to about 80%. 3+ When doped, the first luminescent material may be, for example, at least about 15%, more preferably at least about 30% Tb 3+ ~ approx. 80%Tb 3+ The doped host lattice may have a doping concentration of Mn 4+ In the case of doping, the first luminescent material may have a doped host lattice, for example with a doping concentration of about 0.1 to 30%, most preferably about 1 to 10%. 2+ If doped, the first luminescent material may comprise a doped host lattice, for example with a doping concentration of about 0.1-30%, most preferably about 1-10%.

[0122] In an exemplary embodiment, the first luminescent material is (Ca,Sr)Ga2O6:Eu 3+ (or T.B. 3+ ), (Ca,Sr,Ba)La2Bi2(SiO4)3O:Eu 3+ (or Tb 3+ ), (Ca,Sr,Ba)SnO3:Eu 3+ (and / or Tb 3+ ), (Ca,Y,Gd)MoO4:Eu 3+ (or Tb 3+ ), (Y,Gd)BO3 (pseudo-vaterite):Eu 3+ (or Tb 3+ ), (Y,Tb)SiO5:Eu 3+ (or Tb 3+), A-La2O3:Eu 3+ (or Tb 3+ ), Ba2(SiO4):O 2- :EU 3+ (or Tb 3+ ), Ba2MgSi2O7:Eu 3+ (or Tb 3+ ), Ba2Y(BO3)2Cl:Eu 3+ (or Tb 3+ ), Ba3(PO4)2:Eu 3+ (or Tb 3+ ), Ba3Ca3(PO4)4:Eu 3+ (or Tb 3+ ), Ba3Gd(BO3)3:Eu 3+ (or Tb 3+ ), Ba3Gd2(BO3)4:Eu 3+ (or Tb 3+ ), Ba3La2(BO3)4:Eu 3+ (or Tb 3+ ), Ba3V2O8:Eu 3+ (or Tb 3+ ), Ba3Y2(BO3)4:Eu 3+ (or Tb 3+ ), BaB8O 13 :EU 3+ (or Tb 3+ ), BaBPO5:Eu 3+ (or Tb 3+ ), BaFCl:Eu 3+ (or Tb 3+ ), BaGd2O4:Eu 3+ (or Tb 3+ ), BaGd4Si5O 17 :Sm:Eu 3+ (or Tb 3+ ), BaGdB9O 16 :EU 3+ (or Tb 3+ ), BaLaB9O 16 :EU 3+ (or Tb 3+ ), BaSO4:Eu 3+ (or Tb 3+ ), BaY2F8:Yb:Eu 3+ (or Tb 3+ ), BaY2Si3O 10 :EU 3+(or Tb 3+ ), BaYB9O 16 :EU 3+ (or Tb 3+ ), BaZr(BO3)2:Eu 3+ (or Tb 3+ ), BaZrO3:Eu 3+ (or Tb 3+ ), BaZrO3:Eu 3+ (or Tb 3+ ), b-BaB2O4:Eu 3+ (or Tb 3+ ), B-Gd2O3:Eu 3+ (or Tb 3+ ), Ca2Al(AlSiO7):Eu 3+ (or Tb 3+ ), Ca2Gd2(GeO4)2O:Eu 3+ (or Tb 3+ ), Ca2Gd8(SiO4)6O2:Eu 3+ (or Tb 3+ ), Ca2Gd8Si6O 26 :EU 3+ (or Tb 3+ ), Ca2La8(SiO4)6O2:Eu 3+ (or Tb 3+ ), Ca3(BO3)2:Eu 3+ (or Tb 3+ ), Ca3Al2O6:Eu 3+ (or Tb 3+ ), Ca3Gd2(BO3)4:Eu 3+ (or Tb 3+ ), Ca3La2(BO3)4:Eu 3+ (or Tb 3+ ), Ca3Y2(BO3)4:Eu 3+ (or Tb 3+ ), Ca4GdO(BO3)3:Eu 3+ (or Tb 3+ ), Ca5(PO 11 )3F:Eu 3+ (or Tb 3+ ), Ca5(PO4)3Br:Eu 3+ (or Tb 3+ ), Ca5(PO4)3F:(4f site):Eu 3+ (or Tb 3+), Ca5(PO4)3F:(6h site):Eu 3+ (or Tb 3+ ), Ca5(PO4)3OH:Eu 3+ (or Tb 3+ ), CaBPO5:Eu 3+ (or Tb 3+ ), CaF2:Eu 3+ (or Tb 3+ ), CaLaB7O 13 :EU 3+ (or Tb 3+ ), Calcite-CaCO3:Eu 3+ (or Tb 3+ ), CaO:Eu 3+ (or Tb 3+ ), CaSO4:Eu 3+ (or Tb 3+ ), CaYO(BO3):Eu 3+ (or Tb 3+ ), C-Gd2O3:Eu 3+ (or Tb 3+ ), C-Lu2O3:(C2):Eu 3+ (or Tb 3+ ), C-Lu2O3:(C3i):Eu 3+ (or Tb 3+ ), Cs2NaYF6:Tm:Eu 3+ (or Tb 3+ ), C-Sc2O3:Yb:Eu 3+ (or Tb 3+ ), C-Y2O3:Eu 3+ (or Tb 3+ ),EU 3+ (or Tb 3+ )[(ttfa)3(phen)]0:Eu 3+ (or Tb 3+ ), Gd 17.33 (BO3)4(B2O5)2O 16 :EU 3+ (or Tb 3+ ), Gd2BaZnO5:Eu 3+ (or Tb 3+ ), Gd2O2(SO4):Eu 3+ (or Tb 3+ ), Gd2P4O 13 :EU 3+ (or Tb 3+), Gd3O4Br:Eu 3+ (or Tb 3+ ), Gd3PO7:Eu 3+ (or Tb 3+ ), Gd3Te2Li3O 12 :EU 3+ (or Tb 3+ ), Gd8P2O 17 :EU 3+ (or Tb 3+ ), GdA l3 (BO3) 4:Eu 3+ (or Tb 3+ ), GdAlO3:Eu 3+ (or Tb 3+ ), GdAlO3:Eu 3+ (or Tb 3+ ), GdB3O6:Eu 3+ (or Tb 3+ ), GdBO3:Eu 3+ (or Tb 3+ ), GdGaO3:Eu 3+ (or Tb 3+ ), GdOBr:Eu 3+ (or Tb 3+ ), GdOCl:Eu 3+ (or Tb 3+ ), GdP3O9:Eu 3+ (or Tb 3+ ), GdPO4:Eu 3+ (or Tb 3+ ), I-CaB2O4:Eu 3+ (or Tb 3+ ), InBO3:Eu 3+ (or Tb 3+ ), I-SrB2O4:Eu 3+ (or Tb 3+ ), KCaGd(PO4)2:Eu 3+ (or Tb 3+ ), La 26 O 27 (BO3) 8:Eu 3+ (or Tb 3+ ), La2BaZnO5:Eu 3+ (or Tb 3+ ), La2Hf2O7:Eu 3+ (or Tb 3+ ), La2O2(SO4):Eu 3+ (or Tb3+ ), La2O2S:Eu 3+ (or Tb 3+ ), La2W3O 12 :EU 3+ (or Tb 3+ ), La2Zr3(MoO4)9:Eu 3+ (or Tb 3+ ), La3TaO4Cl6:Eu 3+ (or Tb 3+ ), La3WO6Cl3:Eu 3+ (or Tb 3+ ), LaAlO3:Eu 3+ (or Tb 3+ ), LaB3O6:Eu 3+ (or Tb 3+ ), LaBO3:Eu 3+ (or Tb 3+ ), LaF3:Eu 3+ (or Tb 3+ ), LaGaO3:Eu 3+ (or Tb 3+ ), LaMgBO 10 :EU 3+ (or Tb 3+ ), LaOBr:Eu 3+ (or Tb 3+ ), LaOCl:Eu 3+ (or Tb 3+ ), LaOF:Eu 3+ (or Tb 3+ ), LaOI:Eu 3+ (or Tb 3+ ), LaP3O9:Eu 3+ (or Tb 3+ ), LaPO4:Eu 3+ (or Tb 3+ ), LaYO3:Eu 3+ (or Tb 3+ ), Li2Lu5O4(BO3)3:Eu 3+ (or Tb 3+ ), Li3Ba2La3(MoO4)8:Eu 3+ (or Tb 3+ ), Li3La2(BO3)3:Eu 3+ (or Tb 3+ ), Li6Gd(BO3)3:Eu 3+ (or Tb3+ ), Li6Y(BO3)3:Eu 3+ (or Tb 3+ ), LiCaAlF6:Eu 3+ (or Tb 3+ ), LiEu 3+ (or Tb 3+ ), Mo2O8:Eu 3+ (or Tb 3+ ), LiGd6O5(BO3)3:Eu 3+ (or Tb 3+ ), LiGdF4:Eu 3+ (or Tb 3+ ), LiGdGeO4:Eu 3+ (or Tb 3+ ), LiGdO2:Eu 3+ (or Tb 3+ ), LiGdSiO4:Eu 3+ (or Tb 3+ ), LiLa2O2BO3:Eu 3+ (or Tb 3+ ), LiLaGeO4:Eu 3+ (or Tb 3+ ), LiLaO2:Eu 3+ (or Tb 3+ ), LiLaP4O 12 :EU 3+ (or Tb 3+ ), LiLaSiO4:Eu 3+ (or Tb 3+ ), LiLuGeO4:Eu 3+ (or Tb 3+ ), LiLuO2:Eu 3+ (or Tb 3+ ), LiLuSiO4:Eu 3+ (or Tb 3+ ), LiScO2:Eu 3+ (or Tb 3+ ), LiSr2YO4:Eu 3+ (or Tb 3+ ), LiSrAlF6:Eu 3+ (or Tb 3+ ), LiY6O5(BO3)3:Eu 3+ (or Tb 3+ ), LiYF4:Eu 3+ (or Tb 3+ ), LiYGeO4:Eu3+ (or Tb 3+ ), LiYO2:Eu 3+ (or Tb 3+ ), LiYSiO4:Eu 3+ (or Tb 3+ ), Lu2O2(SO4):Eu 3+ (or Tb 3+ ), Lu2Si2O7:Eu 3+ (or Tb 3+ ), Lu3Al5O 12 :EU 3+ (or Tb 3+ ), Lu3Al5O 12 :Yb:Eu 3+ (or Tb 3+ ), LuBO3:Eu 3+ (or Tb 3+ ), LuBO3 (calcite): Eu 3+ (or Tb 3+ ), LuOCl:Eu 3+ (or Tb 3+ ), LuPO4:Eu 3+ (or Tb 3+ ), Mg2Gd8(SiO4)6O2:Eu 3+ (or Tb 3+ ), Mg2La8(SiO4)6O2:Eu 3+ (or Tb 3+ ), MgO:Eu 3+ (or Tb 3+ ), MgSiO3:Eu 3+ (or Tb 3+ ), Na3YSi3O9:Eu 3+ (or Tb 3+ ), Na6Gd(BO3)3:Eu 3+ (or Tb 3+ ), NaGdGeO4:Eu 3+ (or Tb 3+ ), NaGdO2:Eu 3+ (or Tb 3+ ), NaGdSiO4:Eu 3+ (or Tb 3+ ), NaLaGeO4:Eu 3+ (or Tb 3+ ), NaLaO2:Eu 3+ (or Tb 3+ ), NaLaSiO4:Eu3+ (or Tb 3+ ), NaLuGeO4:Eu 3+ (or Tb 3+ ), NaLuSiO4:Eu 3+ (or Tb 3+ ), NaScO2:Eu 3+ (or Tb 3+ ), NaSrLa(VO4)2:Eu 3+ (or Tb 3+ ), NaYGeO4:Eu 3+ (or Tb 3+ ), NaYSiO4:Eu 3+ (or Tb 3+ ), ScBO3:Eu 3+ (or Tb 3+ ), ScOCl:Eu 3+ (or Tb 3+ ), ScPO4:Eu 3+ (or Tb 3+ ), Sr2B2O5:Eu 3+ (or Tb 3+ ), Sr2Gd8(SiO4)6O2:Eu 3+ (or Tb 3+ ), Sr2La2Zn2O7:Eu 3+ (or Tb 3+ ), Sr2La2Zn2O7:Eu 3+ (or Tb 3+ ), Sr2LaAlO5:Eu 3+ (or Tb 3+ ), Sr3(BO3)2:Eu 3+ (or Tb 3+ ), Sr3(PO4)2:Eu 3+ (or Tb 3+ ), Sr3(PO4)2:Sm:Eu 3+ (or Tb 3+ ), Sr3Gd2(BO3)4:Eu 3+ (or Tb 3+ ), Sr3La2(BO3)4:Eu 3+ (or Tb 3+ ), Sr3La6(SiO4)6:Eu 3+ (or Tb 3+ ), Sr3Y2(BO3)4:Eu 3+ (or Tb 3+ ), Sr5(PO4)3F:Eu3+ (or Tb 3+ ), Sr9Ln(VO4)7:Eu 3+ (or Tb 3+ ), SrAl2B2O7:Eu 3+ (or Tb 3+ ), SrB4O7:Eu 3+ (or Tb 3+ ), SrBO 10 :EU 3+ (or Tb 3+ ), SrCO3:Eu 3+ (or Tb 3+ ), SrGdAlO4:Eu 3+ (or Tb 3+ ), SrHfO3:Tm:Eu 3+ (or Tb 3+ ), SrLa2BeO5:(4c):Eu 3+ (or Tb 3+ ), SrLa2BeO5:(8d):Eu 3+ (or Tb 3+ ), SrLaAlO4:Eu 3+ (or Tb 3+ ), SrLaGa3O7:Eu 3+ (or Tb 3+ ), SrLaO(BO3):Eu 3+ (or Tb 3+ ), SrO:Eu 3+ (or Tb 3+ ), SrY2O4:(Sr site):Eu 3+ (or Tb 3+ ), SrY2O4:(Y site 1):Eu 3+ (or Tb 3+ ), SrY2O4:(Y site 2):Eu 3+ (or Tb 3+ ), Tb2Mo3O 12 :EU 3+ (or Tb 3+ ), Tb2W3O 12 :EU 3+ (or Tb 3+ ), TbBO3:Eu 3+ (or Tb 3+ ), ThO2:Eu 3+ (or Tb 3+ ), X1-Gd2SiO5:Eu 3+ (or Tb3+ ), X1-Y2SiO5:Eu 3+ (or Tb 3+ ), X2-Y2SiO5:Eu 3+ (or Tb 3+ ), Y 17.33 (BO3)4(B2O5)2O 16 :EU 3+ (or Tb 3+ ), Y2Ge2O7:Eu 3+ (or Tb 3+ ), Y2GeO5:Eu 3+ (or Tb 3+ ), Y2O2(SO4):Eu 3+ (or Tb 3+ ), Y2O2S:Eu 3+ (or Tb 3+ ), Y2O2S:Eu 3+ (or Tb 3+ ), Y2O3:Eu 3+ (or Tb 3+ ), Y2P4O 13 :EU 3+ (or Tb 3+ ), Y2Si2O7:Eu 3+ (or Tb 3+ ), Y2SiO5:Eu 3+ (or Tb 3+ ), Y3Al5O 12 :EU 3+ (or Tb 3+ ), Y3O4Br:Eu 3+ (or Tb 3+ ), Y3O4Cl:Eu 3+ (or Tb 3+ ), Y3PO7:Eu 3+ (or Tb 3+ ), Y4GeO8:Eu 3+ (or Tb 3+ ), Y8P2O 17 :EU 3+ (or Tb 3+ ), YAl3(BO3)4:Eu 3+ (or Tb 3+ ), YAlO3:Eu 3+ (or Tb 3+ ), YBO3:Eu 3+ (or Tb 3+ ), YbOBr:Yb:Eu 3+(or Tb 3+ ), YF3:Eu 3+ (or Tb 3+ ), YOBr:Eu 3+ (or Tb 3+ ), YOCl:Eu 3+ (or Tb 3+ ), YOCl:Eu 3+ (or Tb 3+ ), YOF:Eu 3+ (or Tb 3+ ), YOF:Eu 3+ (or Tb 3+ ), YP3O9:Eu 3+ (or Tb 3+ ), YPO4:Eu 3+ (or Tb 3+ ), YTaO4:Eu 3+ (or Tb 3+ ), YVO4:Eu 3+ (or Tb 3+ ), ZrP2O7:Eu 3+ (or Tb 3+ ), Y3Al5O 12 :Ce 3+ , Lu3Al5O 12 :Ce 3+ or a combination thereof.

[0123] Those skilled in the art will appreciate that 3+ (or:Tb 3+ or:Ce 3+ , or: Mn 2+ , or: Mn 4+ ) indicates that the host lattice is Eu 3+ (or:Tb 3+ Or:Ce 3+ Or: Mn 2+ Or: Mn 4+ Understand that this refers to being doped.

[0124] Second Luminescent Material As discussed, the first luminescent material may include nanoparticles according to the present invention.

[0125] In a preferred embodiment, the first luminescent material contains the nanoparticles according to the present invention, and the second luminescent material contains the nanoparticles of the present invention. The luminescent nanoparticles according to the present invention are sufficiently suitable for use in a luminescent composition. More preferably, the second luminescent material is A synthesized using the method of the present invention 2-x O3:Ln x type [wherein Ln is cerium, or cerium and terbium] nanoparticles. These ions have the desired light absorption / emission properties. More preferably, the second luminescent material is A13A25O 12 :Ln type [wherein A1 is one or more selected from the group consisting of yttrium, lutetium and gadolinium; A2 is one or more selected from the group consisting of aluminum, gallium and scandium, and Ln is cerium, or cerium and terbium] nanoparticles of the present invention. Even more preferably, the second luminescent material is (Lu,Y)3Al5O 12 :Ln type [wherein Ln is cerium, or cerium and terbium] nanoparticles of the present invention.

[0126] In a preferred embodiment, the first luminescent material contains the nanoparticles according to the present invention, and the second luminescent material is preferably as described below. More preferably, the first luminescent is A synthesized using the method of the present invention 2-x O3:Ln x type [wherein A is one or more of yttrium, scandium, aluminum, gallium or lanthanide; Ln is one or more of cerium, europium, terbium; 0 < x < 2] luminescent nanoparticles, and the second luminescent material is as described below.

[0127] A suitable inorganic luminescent material may be used as the second luminescent material. The second material can absorb light of the second wavelength. The second wavelength may be any wavelength range of interest.

[0128] Preferably, the second luminescent material has one or more excitation bands in the wavelengths between 380 and 580 nm, preferably the second luminescent material has one or more excitation bands in the UV-A (315-400 nm), violet (400-440 nm), blue (440-480 nm) or green (510-560 nm) wavelengths, most preferably in the blue (440-480 nm) wavelengths. (Al,In,Ga)N based LEDs provide efficient "pump" light generation in the violet to blue wavelengths (about 400 nm to about 480 nm). An example of a blue excitable material is CaAlSiN3:Eu 2+ , Y3Al5O 12 :Ce 3+ It is.

[0129] In another aspect of the invention, the second luminescent material is a material having one or more excitation bands at 700-1400 nm (IR-A), 580-600 nm (amber and / or orange), 560-580 nm (yellow), 510-560 nm (green), 480-510 nm (cyan), 440-480 nm (blue), 400-440 nm (violet), 315-400 nm (UV-A) and / or 280-315 nm (UV-B).

[0130] In a preferred embodiment, the host lattice of the second luminescent material is a garnet, a fluoride, a silicate, a phosphate or a nitride, more preferably YAlO 12 (YAG), Lu3Al5O 12 (LuAG), MgF2, CaF2, Sr2SiO4, Ba2SiO4, Ca2MgSi2O7, LiSrPO4, CaAlSiN3 or combinations thereof. Preferably, the preferred host lattice of the second luminescent material is selected from the group consisting of Eu 2+ , Pb 2+ , Bi 3+ and Ce 3+ More preferably, the one or more ions selected from the group consisting of Eu 2+ Or Ce 3+ , Tb 3+ In combination with, most preferably, Ce 3+ Tb3+ is doped in combination with

[0131] Preferably, the host lattice of the second luminescent material or its precursor is Y3Al5O 12 (YAG) or Lu3Al5O 12 (LuAG), or a garnet such as a combination thereof. Most preferably, the host lattice is Y3Al5O 12 (YAG) or Lu3Al5O 12 (LuAG) or a combination thereof selected from the group consisting of, and as a dopant, Tb as required 3+ in combination with Ce 3+ is mentioned.

[0132] Preferably, in the case of Ce 3+ doping, the second luminescent material has a host lattice doped at a level of about 0.05 to 5%, more preferably about 0.1 to 4%.

[0133] Preferably, the first material is A 2-x O3:Ln x type [wherein A is one or more of yttrium, scandium, aluminum, gallium or lanthanide; Ln is europium; 0 < x < 2] of the luminescent nanoparticles of the present invention, and the second material is Ce 3+ or Tb 3+ doped Y3Al5O 12 is. More preferably, the Y3Al5O 12 material is provided as nanoparticles.

[0134] In a preferred embodiment, the first material is A 2-x O3:Ln x type [wherein A is one or more of yttrium, scandium, aluminum, gallium or lanthanide; Ln is europium and / or terbium] of the luminescent nanoparticles of the present invention, and the second material is A 2-x O3:Ln xLuminescent nanoparticles synthesized using the method of the present invention are of the type: where A is one or more of yttrium, scandium, aluminum, gallium, or a lanthanide; Ln is cerium and / or terbium.

[0135] The present invention further relates to a light emitting device comprising a luminescent material obtainable by the method according to the present invention. Preferably, the light emitting device further comprises an excitation source for a luminescent material, such as a second luminescent material. Preferably, the excitation source is a UV-A, violet or blue light emitting material, which emits light towards the luminescent material at a wavelength of 315-400 nm (UV-A), 400-440 nm (violet) or 440-480 nm (blue), more preferably 430-465 nm.

[0136] A light emitting device may be constructed from a blue emitting LED having rare earth metal doped garnet nanoparticles or luminescent compositions according to the present invention deposited on the LED chip. The nanoparticles according to the present invention may be bonded to a polymer or silicone slurry deposited on the blue LED chip and subsequently cured.

[0137] The present invention further relates to a lighting system comprising a light emitting device according to the present invention, preferably selected from the group consisting of a lamp or luminaire, an office lighting system, a domestic application system, a shop lighting system, a residential lighting system, an accent lighting system, a spot lighting system, a theatre lighting system, a fiber optic application system, a projection system, a self-illuminated display system, a pixelated display system, a segmented display system, a warning signal system, a medical lighting application system, a sign system and a decorative lighting system, a portable system, an automotive application and a greenhouse lighting system.

[0138] The present invention further relates to the use of the luminescent material comprising the luminescent composition according to the present invention or the nanoparticles synthesized using the method of the present invention as a taggant. A taggant is a marker added to a material to allow various forms of testing. The excitation / emission spectrum of the luminescent material and / or the luminescent composition according to the present invention as a whole may have unique distinguishing characteristics compared to conventional approaches, and may therefore be useful as a taggant in anti-counterfeiting applications. For example, US Patent No. 7,667,828 (B) discloses a tagging system containing multiple types of taggants that are different from each other.

[0139] The present invention will now be further illustrated by the following non-limiting examples. EXAMPLES

[0140] Example 1 Y 2 O 3 :EU 3+ Synthesis of nanoplatelets (15% Eu) Preparation of the First Mixture and the Second Mixture First mixture: - Yttrium acetate (0.2 mol or 0.17 mol for 15 mol% Eu doping): 38.4 g of yttrium oxide was mixed with 1 L of water and 100 ml of acetic acid (100%) and dissolved at approximately 100-150°C. - Europium acetate (0.03 mol): 10.56 g of europium oxide was dissolved in 500 ml of water and 25 ml of acetic acid. Dissolved europium acetate was added to the yttrium acetate solution, which was adjusted to 2 L, corresponding to a doping concentration of 15%.

[0141] Second mixture: - Ammonium bicarbonate (AHC) solution: 316.224 g of AHC was dissolved in 1 L of water with ammonia (NH3) and then adjusted to 2 L. The amount of NH3 was such that the final pH was 10.

[0142] Contacted by MJR The first and second mixtures were introduced separately into a microjet reactor. The nozzle size of the MJR was 200 μm. The pump pressure was 50 bar. The contacting was carried out at room temperature (around 20° C.) and ambient pressure (around 1 bar). The nanosized particles precipitated, yielding a third mixture. The third mixture containing the precipitated particles was centrifuged and freeze-dried.

[0143] heating The washed and dried precipitate was heated under the following conditions: - Heating rate: 5K / min - Temperature: 600℃ - Residence time: 1 hour - Atmosphere: Air

[0144] The nanosized particles were in the form of nanoplatelets with diameters ranging from 50 nm to 5 μm and estimated thicknesses ranging from 2 to 20 nm.

[0145] Example 2 Synthesis of YAG:Ce nanoparticles Preparation of the First Mixture and the Second Mixture First mixture: - Yttrium nitrate (0.3 mol or 0.2955 mol for Ce doping): 33.37 g of yttrium oxide was mixed with 0.5 L of water and 85.9 g of HNO3 (about 55 ml) and dissolved at about 150°C. - Cerium acetate (0.0045 mol): 1.55 g of cerium acetate was dissolved in 100 ml of water. The dissolved cerium acetate was added to the yttrium nitrate solution, which was adjusted to 1 L, corresponding to a doping concentration of 1.5% based on Y. - Aluminum nitrate (0.5 mol): 187.57 g of aluminum nitrate was dissolved in 0.5 L of water and then made up to 1 L. The two solutions were combined to give 2 L of metal salt solution.

[0146] Second mixture: - Ammonium bicarbonate (AHC) solution: 158.12g AHC was dissolved in 1L water with 400ml ammonia (NH3) and then adjusted to 2L. The pH was >9.

[0147] Contacted by MJR The first and second mixtures were introduced separately into a microjet reactor. The nozzle size of the MJR was 200 μm. The pump pressure was 50 bar. The contacting was carried out at room temperature (around 20 °C) and ambient pressure (around 1 bar). The nanosized particles precipitated to obtain a third mixture. The pH value of the precipitated mixture was adjusted to 7-7.5 using a 1 M HNO3 solution. The third mixture containing the precipitated particles was centrifuged and washed with demineralized water (15 times). The centrifuged particles were mixed with a K2SO4 solution and then freeze-dried.

[0148] heating The freeze-dried particles were heated under the following conditions: - Heating rate: 5K / min - Temperature: 950℃ - Residence time: 3 hours - Atmosphere: N2

[0149] After heating, the particles were washed with demineralized water to remove K2SO4.

[0150] The resulting particles had a size of approximately 50 nm.

[0151] Example 3 LaPO 4 :Tb 3+ +Y 2 O 3 :EU 3+ Energy transfer in mixtures A solution of 100 mg NaOH in 5 ml deionized water was prepared. 100 mg LaPO4:50%Tb nanoparticles were added to the solution and the solution was stirred for 1 h at room temperature. The sample was centrifuged at 2000 rpm for 10 min and washed twice with deionized water. The treated LaPO4:Tb particles were dried at 150 °C on a heating plate.

[0152] The treated LaPO4:Tb particles were mixed with 100 mg of YO3:Eu nanoparticles prepared according to Example 1 and dispersed in 15 mL of deionized water. The dispersion was sonicated for 3 h and then dried at 105 °C with stirring.

[0153] Tb 3+ When irradiated with 486 nm light, which can excite only Eu 3+ Emission was detected in the 670-720 nm region, where only fluorescein emits, thus demonstrating energy transfer.

[0154] Example 4 YAG:Tb 3+ +Y 2 O 3 :EU 3+ Energy transfer in mixtures Y3Al5O 12 :50%Tb was obtained according to the procedure in J. Mater. Chem. C, 2017, 5, 12561.

[0155] 100 mg of YAG:Tb particles were mixed with 100 mg of Y2O3:Eu nanoparticles prepared according to Example 1 and dispersed in 15 mL of deionized water. The dispersion was sonicated for 3 h and then dried at 105 °C with stirring.

[0156] Tb 3+ When irradiated with 486 nm light, which can excite only Eu 3+ Emission was detected in the 670-720 nm region, where only fluorescein emits, thus demonstrating energy transfer.

[0157] Example 5 YAG: Ce, Tb + Y 2 O 3 :EU 3+ Energy transfer in mixtures Y3Al5O 12 : 50% Tb, 0.1% Ce was obtained according to the procedure in J. Mater. Chem. C, 2017, 5, 12561.

[0158] 100 mg of YAG:Tb,Ce particles were mixed with 100 mg of YO:Eu nanoparticles prepared according to Example 1 and dispersed in 15 mL of deionized water. The dispersion was sonicated for 3 h and then dried at 105 °C with stirring.

[0159] Ce 3+ When irradiated with 440 nm light, which can excite only Eu 3+ and Tb 3+ Emission was detected in the 530-720 nm region, where fluorescein is emitted, thus proving the energy transfer.

Claims

1. A ２－ｘ O ３ : Ln ｘ 1. A method for making luminescent nanoparticles of the type wherein A is one or more of yttrium, scandium, aluminum, gallium, or a lanthanide; Ln is at least one lanthanide; and 0<x<2, comprising the steps of: providing a first mixture comprising at least a salt of A, a salt of Ln, and a solvent; providing a second mixture comprising a precipitant and a solvent; contacting the first mixture with the second mixture in a microjet reactor to obtain a third mixture comprising nanoparticles; and heating the nanoparticles; Including, The method, wherein the contacting is carried out at 50° C. or less, and the first mixture and the second mixture are fed separately into the microjet reactor.

2. Ln is selected from the group consisting of europium, terbium or cerium, and / or The nanoparticles are Al ３ A2 ５ O １２ : Ln type [wherein A1 is one or more selected from the group consisting of yttrium, lutetium and gadolinium; A2 is one or more selected from the group consisting of aluminum, gallium and scandium; and Ln is at least one lanthanide], The method of claim 1.

3. The method of claim 1 or 2, wherein the first mixture comprises an acid or a base, and preferably the pH of the first mixture is 4 to 5.

4. 4. The method according to any one of claims 1 to 3, wherein the pH of the second mixture is above 7 and / or the precipitating agent is a base, preferably the precipitating agent is urea or ammonium bicarbonate.

5. The method according to any one of claims 1 to 4, wherein the contacting is carried out at room temperature or at 15°C to 30°C and / or at a pressure of up to 5 bar, preferably 0.5 bar to 5 bar.

6. The nanoparticles are Y ２ O ３ : Ln, Sc ２ O ３ : Ln, Lu ２ O ３ : Ln and / or Gd ２ O ３ :Ln type, and preferably the pH of the second mixture is greater than 8, and / or The pH of the third mixture is 7.5 to 11, more preferably 8 to 10. The method according to any one of claims 1 to 5.

7. The nanoparticles are Al ３ A2 ５ O １２ : Ln type [wherein A1 is one or more selected from the group consisting of yttrium, lutetium and gadolinium; A2 is one or more selected from the group consisting of aluminum, gallium and scandium; and Ln is at least one lanthanide], and the pH of the second mixture is between 7 and 9; and / or The pH of the third mixture is 6 to 9, preferably 7 to 7.

5. The method according to any one of claims 1 to 6.

8. 8. The method of claim 1, wherein the microjet reactor has a nozzle size of 200 to 300 μm, and / or the first mixture and the second mixture are fed to the microjet reactor at a pump pressure of about 50 bar.

9. The heating D ５０ heating particles having a size of 1 nm or more, more preferably 2 nm or more, and 100 nm or less, more preferably 20 nm or less; heating the nanoparticles to above 200°C; preferably at least 500°C, for example 200-1500°C or 500-1600°C, preferably 300-1200°C or 500-1300°C, preferably for at least 30 seconds, more preferably at least 1 minute, more preferably 1.5 minutes to 3 hours; The method according to any one of claims 1 to 8, comprising:

10. The heating comprises heating a mixture comprising the nanoparticles and a protective matrix, and preferably the protective matrix is ​​a salt, and / or The mixture dry blending the nanoparticles with the protective matrix; mixing said nanoparticles and said salt in a liquid to obtain a dispersion, and preferably separating said liquid from said dispersion; and / or preparing an emulsion comprising a continuous phase and a dispersed phase comprising said nanoparticles and said protective matrix, preferably demulsifying said emulsion and separating liquid from said demulsified emulsion; Manufactured by The method according to any one of claims 1 to 9.

11. Nanoparticles obtainable by the method according to any one of claims 1 to 10, preferably The Ln is Tb ３＋ , Eu ３＋ and Ce ３＋ and / or The nanoparticles comprise active ions arranged in a host lattice, the host lattice being more preferably selected from the group of garnets and metal oxides, and even more preferably the host lattice is Al ３ A2 ５ O １２ type wherein A1 is one or more selected from the group consisting of yttrium, lutetium and gadolinium; A2 is one or more selected from the group consisting of aluminum, gallium and scandium; and / or the host lattice is of the type Y ３ Al ５ O １２ , Lu ３ Al ５ O １２ Or Y ２ O ３ Selected from: Nanoparticles.

12. A luminescent composition comprising the nanoparticles of claim 11.

13. 13. The luminescent composition of claim 12, wherein the luminescent composition comprises a first luminescent material and a second luminescent material, the first luminescent material and the second luminescent material being selected such that the second luminescent material has an emission spectrum that at least partially overlaps with one or more excitation bands of the first luminescent material, and the first luminescent material and / or the second luminescent material comprises the nanoparticles of claim 11.

14. 14. A light emitting device comprising nanoparticles according to claim 11 or a luminescent composition according to claim 12 or 13, preferably further comprising an excitation source.

15. 15. A lighting system comprising a light emitting device according to claim 14, preferably selected from the group consisting of lamps or luminaires, office lighting systems, home systems, shop lighting systems, residential lighting systems, accent lighting systems, spot lighting systems, theatre lighting systems, fiber optic systems, projection systems, self-emissive display systems, pixelated display systems, segmented display systems, warning sign systems, medical lighting systems, indicator sign systems and decorative lighting systems, portable systems, automotive and greenhouse lighting systems, and anti-counterfeiting.