Method of treating luminescent nanoparticles

Abstract

The present invention provides a method for providing a composite luminescent particle, comprising: (a) providing (i) a luminescent material comprising (A1-xBx) 3 (C1-yDy) 5O12 nanoparticles or a precursor thereof, A comprising one or more of yttrium, lutetium, gadolinium, lanthanum; b comprises one or more rare earth elements; c comprises one or more of aluminum, gallium and scandium; d comprises one or more transition metal ions; 0 < = x < = 1, 0 < = y < = 1, x + ygt; 0; and (ii) also providing an oxide material precursor, the oxide material having a melting point of at least 850 DEG C; (b) mixing (i) a luminescent material comprising (A1-xBx) 3 (C1-yDy) 5O12 nanoparticles or a precursor thereof with (ii) an oxide material precursor; (c) curing the oxide material precursor to obtain cured particles which comprise a luminescent material and an oxide material coating layer; (d) heating the cured particles at a first temperature of 600 DEG C or more for a first duration of 10 minutes or more; and (c) heating the cured particles at a second temperature of 700 DEG C or more for a second duration of 1 hour or more in a reducing atmosphere including carbon monoxide.

Description

Technical Field

[0001] This invention relates to the treatment of luminescent nanoparticles. It also relates to obtaining luminescent nanoparticles from precursor particles. Furthermore, it relates to treated or obtained luminescent nanoparticles. Finally, it relates to luminescent compositions comprising treated or obtained luminescent nanoparticles, and methods for preparing said luminescent compositions. Finally, it relates to applications and apparatuses comprising the luminescent nanoparticles or luminescent compositions of this invention. Background Technology

[0002] Luminescent downconversion materials play an important role in solid-state lighting devices used in illumination and real-world applications. These materials can also be used as tracers, for example, in security inks.

[0003] Nanomaterials have attracted much attention due to their small size. In theory, nanoparticles could be readily applied to a wide range of applications. However, suitable nanomaterials often suffer from poor quality (chemical, stability, optical, and / or physical) due to their small size and poor crystallinity. WO2021043762A1 teaches annealing nanoparticles to improve lattice compaction (quality), homogeneity, phase purity, and photoluminescence properties. However, further improvements are still needed.

[0004] Cerium-doped yttrium aluminum garnet (YAG:Ce) is the benchmark phosphor for solid-state LED lighting. In microcrystalline form (or as a bulk single crystal / ceramic), YAG:Ce exhibits high efficiency; however, at the nanoscale, it typically suffers from weak emission intensity, low conversion efficiency, and poor stability, primarily due to the high specific surface area of ​​the nanoparticles and the associated poor uniformity of Ce within the nanoparticle lattice.

[0005] Wet chemical synthesis (solvothermal, precipitation, sol-gel, etc.) yields YAG:Ce nanoparticles with sizes as low as 5 nm. These synthesized nano-YAG:Ce may contain impurity phases, have weaker lattices, and exhibit poorer photoluminescence (PL) properties.

[0006] Revaux et al. Nanoscale A solvothermal synthesis of YAG:Ce nanoparticles was disclosed in 2011, 3, and 2015-2022, followed by incorporation into a porous silica matrix, drying, and grinding. The powder was then annealed in air at 1000°C for 12 hours and in Ar / 10% H₂ at 600°C for 12 hours. The photoluminescence quantum yield (PLQY) of the final material was reported to be approximately 60%. PL stability was also improved compared to as-synthesized solvothermal precursor nanoparticles.

[0007] WO2018 / 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 has an emission spectrum that at least partially overlaps with one or more excitation bands of the luminescent material, and wherein the luminescent material and the sensitizer are arranged to allow nonradiative energy transfer from the sensitizer material to the luminescent material. The application also describes a method for its preparation.

[0008] Nonradiative energy transfer from sensitizer to luminescent material (sometimes also called fluorescence resonance energy transfer, FRET) involves the nonradiative transfer of energy from excited sensitizer ions in the sensitizer material to acceptor (or luminescent) ions in the luminescent material. This can be verified by the following: once the sensitizer ions in the sensitizer material are selectively excited, the emission of luminescent ions from the luminescent material increases.

[0009] Nanomaterials have attracted much attention due to their high specific surface area and small size, which allows luminescent materials to be spatially close-packed to utilize interparticle FRET. In order to effectively utilize interparticle FRET, the size of the luminescent particles must be very small (<10 nm).

[0010] Therefore, there remains a need for luminescent nanomaterials with improved quality and stability at small sizes. Furthermore, there is a need for luminescent compositions exhibiting high photoluminescence quantum yield (QY) and improved stability, as well as methods for their preparation. Summary of the Invention

[0011] A method for providing composite luminescent particles is provided, comprising: (a) Provide (i) Includes (A) 1-x B x )3(C 1-y D y )5O 12 The luminescent nanoparticle material, wherein A comprises one or more of yttrium, lutetium, gadolinium, and lanthanum; B comprises one or more rare earth elements; C comprises one or more of aluminum, gallium, and scandium; D comprises one or more transition metal ions; and wherein 0 ≤ x ≤ 1, 0 ≤ y ≤ 1, and x + y > 0; and (ii) further provides a precursor of an oxide material, wherein the oxide material has a melting point of at least 850 °C; (b) including (i) (A) 1-x B x )3(C 1-y D y )5O 12 The luminescent nanoparticles are mixed with the precursor of the oxide material described in (ii); (c) The precursor of the oxide material is cured to obtain cured particles, the cured particles comprising the luminescent material and the coating of the oxide material. (d) Heating the cured particles at a first temperature for a first duration, wherein the first temperature is 600°C or higher, and wherein the first duration is 10 minutes or longer; and (e) The cured particles are heated at a second temperature for a second duration in a reducing atmosphere including carbon monoxide, wherein the second temperature is 700°C or higher, and wherein the second duration is 1 hour or longer. Preferably, the (A) 1-x B x )3(C 1-y D y )5O 12 Nanoparticles are obtained by a solvothermal method, more preferably by a glycothermal method.

[0012] A method for obtaining composite luminescent particles is also provided, comprising: (a) Provide (i) (A 1-x B x )3(C 1-y D y )5O 12 The precursor material for nanoparticles, wherein A comprises one or more of yttrium, lutetium, gadolinium, and lanthanum; B comprises one or more rare earth elements; C comprises one or more of aluminum, gallium, and scandium; D comprises one or more transition metal ions; and wherein 0 ≤ x ≤ 1, 0 ≤ y ≤ 1, and x + y > 0; and (ii) further provides a precursor of an oxide material, wherein the oxide material has a melting point of at least 850 °C; (b) Mix the precursor material described in (i) with the precursor of the oxide material described in (ii); (c) Curing the precursor of the oxide material to obtain cured particles, the cured particles comprising the precursor material and a coating layer of the oxide material; (d) Heating the cured particles at a first temperature for a first duration, wherein the first temperature is 600°C or higher, and the first duration is 10 minutes or longer; and (e) The cured particles are heated at a second temperature for a second duration in a reducing atmosphere including carbon monoxide, wherein the second temperature is 700°C or higher, and wherein the second duration is 1 hour or longer. The precursor material is preferably obtained by precipitation.

[0013] It has been found that the method of the present invention can obtain luminescent particles exhibiting high photoluminescence quantum yield, improved spectral properties, and improved photostability.

[0014] Also provided are composite luminescent particles obtained by the method of the present invention, comprising: (i) (A) 1-x B x )3(C 1-y D y )5O 12 The composite luminescent particles, and (ii) a coating layer of oxide material with a melting point of 850°C or higher, wherein A comprises one or more of yttrium, lutetium, gadolinium, and lanthanum; B comprises one or more rare earth elements; C comprises one or more of aluminum, gallium, and scandium; D comprises one or more transition metal ions; and 0 ≤ x ≤ 1, 0 ≤ y ≤ 1, and x + y > 0, have the following characteristics: - Photoluminescence quantum yield greater than 60%, preferably greater than 80%; - Photostability of the storage medium, such that the photoluminescence intensity after two weeks of storage in a non-inert atmosphere is at least 80% of the initial photoluminescence intensity; - Photostability under illumination allows for >0.1 W / cm² at suitable excitation wavelengths. 2 Under illumination, it retains at least 50% of its initial photoluminescence intensity after 10 hours, preferably at least 50% of its initial photoluminescence intensity after 15 hours; and - When B includes cerium, the peak ratio in the excitation spectrum is greater than 20 (between 455 nm and 380 nm).

[0015] Luminescent compositions are also provided.

[0016] A luminescent composition is provided, comprising a first luminescent material and a second luminescent material, wherein at least one of the first luminescent material and the second luminescent material comprises the composite luminescent particles of the present invention. Preferably, the first luminescent material is capable of emitting light in a first wavelength range, the second luminescent material is capable of absorbing light in a second wavelength range, and has an emission spectrum that at least partially overlaps with one or more excitation bands of the first luminescent material. More preferably, the first luminescent material and the second luminescent material are arranged relative to each other to allow nonradiative energy transfer from the second luminescent material to the first luminescent material. Even more preferably, both the first luminescent material and the second luminescent material comprise the composite luminescent particles of the present invention.

[0017] A luminescent composition is also provided, obtained by the method according to the invention, the luminescent composition comprising: (i) a first luminescent material comprising (A 1-x B x )3(C 1-y D y)5O 12 (ii) a first luminescent material comprising nanoparticles of a phosphor material doped with rare earth, s2-configuration, or transition metal ions, preferably wherein the first luminescent material is capable of emitting light in a first wavelength range, the second luminescent material is capable of absorbing light in a second wavelength range, and has an emission spectrum that at least partially overlaps with one or more excitation bands of the first luminescent material, more preferably wherein the first and second luminescent materials are arranged to allow nonradiative energy transfer from the second luminescent material to the first luminescent material. Attached Figure Description

[0018] Figure 1 The luminescent particles according to the present invention are schematically shown, with A after coating and baking, and B after an additional etching step.

[0019] Figure 2 The image shows a TEM image of nano-YAG:Ce synthesized by co-precipitation method with calcination at 1025 °C according to Comparative Experiment A.

[0020] Figure 3 The image shows a TEM image of nano-YAG:Ce synthesized by a solvothermal method with calcination at 1025 °C according to Comparative Experiment B.

[0021] Figure 4 TEM image of nano-YAG:Ce synthesized by co-precipitation method according to Example 1, which involves encapsulation in silica and calcination at 1025°C.

[0022] Figure 5 The image shows a TEM image of nano-YAG:Ce synthesized by a solvothermal method according to Example 2, which was encapsulated in silica and calcined at 1025°C.

[0023] Figure 6 The reflectance spectra of nano-YAG:Ce are shown according to Comparative Experiment A (thin dashed line) and according to Example 1 (thick solid line).

[0024] Figure 7 The reflectance spectra of nano-YAG:Ce are shown according to Comparative Experiment E (thin dashed line) and Example 1 (thick solid line).

[0025] Figure 8 The reflectance spectra of nano-YAG:Ce are shown according to comparative experiment F (thin dashed line) and Example 2 (thick solid line).

[0026] Figure 9 The image shows a TEM image of nano-YAG:Ce synthesized by a solvothermal method according to Example 3, which involves encapsulation in silica, calcination at 1025°C, and etching with 2M NaOH solution for 24 hours.

[0027] Figure 10 The image shows a TEM image of nano-YAG:Ce synthesized according to Example 4 by a solvothermal method, which involves encapsulation in silica, calcination at 1025°C, etching with 2M NaOH solution for 24 hours, and annealing at 800°C for 8 hours in a reducing atmosphere.

[0028] Figure 11 The emission intensity of YAG:Ce,Tb nanoparticles with 0% Tb, 15% Tb, 20% Tb, 50% Tb, and 65% Tb is shown as a function of time.

[0029] Figure 12 The diagram shows the change in emission intensity of the sample on a medium-power LED over time. Detailed Implementation

[0030] A method for processing luminescent nanoparticles and a method for obtaining luminescent nanoparticles are provided. The difference between these methods lies in the material (i) provided in step (a).

[0031] Both methods include step (a) of providing (i) including (A) 1-x B x )3(C 1-y D y )5O 12 luminescent materials of nanoparticles or (A) 1-x B x )3(C 1-y D y )5O 12 (ii) a precursor material for nanoparticles, and further, a precursor material for an oxide material, wherein the oxide material has a melting point of at least 850°C.

[0032] (i) includes (A 1-x B x ) 3 (C 1-y D y ) 5 O 12 luminescent materials of nanoparticles or (A) 1-x B x ) 3 (C 1-y D y ) 5O 12 Nanoparticles precursor materials Preferably, the luminescent material or precursor material is provided as particles, wherein the minimum size of the particles is D 50 The value is ≥0.5 nm and ≤100 nm. This makes it possible to obtain microdomains within an oxide material matrix.

[0033] Preferably, as measured using a transmission electron microscope (TEM), the minimum size D of the particles of the luminescent material or the precursor material is... 50 The value is ≥0.5 nm and ≤50 nm, more preferably ≥0.5 nm and ≤20 nm.

[0034] Preferably, the D of the particles of the luminescent material or the precursor material is... 50 Value ≥ 0.5 nm and ≤ 100 nm. In the case of discrete particles, the D of the particles... 50 More preferably, the value is ≥0.5 nm and ≤50 nm, even more preferably ≤20 nm. In the case of aggregated particles, the BET specific surface area is preferably ≥10 m², as measured by the BET physical adsorption method. 2 / g, more preferably ≥15 m 2 / g, and the aggregates are preferably D 50 ≤100 nm. Smaller particles allow for smaller microregions, which in turn allow for better FRET.

[0035] Including (A) 1-x B x ) 3 (C 1-y D y ) 5 O 12 Luminescent materials of nanoparticles In the first embodiment, step (a) includes providing (i) including (A) 1-x B x )3(C 1-y D y )5O 12 The luminescent material is composed of nanoparticles. A includes one or more of yttrium, lutetium, gadolinium, and lanthanum; B includes one or more other rare earth elements; C includes one or more of aluminum, gallium, and scandium; D includes one or more transition metal ions; and 0 ≤ x ≤ 1, 0 ≤ y ≤ 1, and x + y > 0.

[0036] Rare earth elements are defined in this paper as yttrium, scandium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium. Transition metal ions are defined in this paper as any element having a partially filled d subshell, or an element capable of forming a stable cation with unfilled d orbitals.

[0037] Preferably, B includes one or more of cerium, terbium, and europium. These ions exhibit strong emission in the visible spectrum.

[0038] More preferably, B includes cerium and C includes aluminum. These are cerium-doped aluminum garnet type nanoparticles, such as yttrium aluminum garnet (YAG:Ce), lutetium aluminum garnet (LuAG:Ce), gadolinium aluminum garnet (GdAG:Ce), lanthanum aluminum garnet (LaAG:Ce), terbium aluminum garnet (TbAG:Ce), or combinations thereof, such as (Y,Lu)AG:Ce.

[0039] Preferably, D includes Mn 2+ Mn 4+ and / or Cr 3+ One or more of these ions. These ions exhibit strong emission in the visible spectrum.

[0040] Preferably, the luminescent nanoparticles are obtained via a solvothermal method. Solvothermal synthesis involves heating a metal salt suspended in a solvent to generate a colloidal solution of ultrafine metal oxide particles. The particles obtained via solvothermal synthesis are typically discrete particles. Preferably, the luminescent nanoparticles have a D... 50 The value is ≥0.5 nm and ≤50 nm, more preferably ≥0.5 nm and ≤20 nm.

[0041] Preferably, the solvothermal method is the glycothermal method. In glycothermal synthesis, a diol is used as the solvent. Such glycothermal methods are described, for example, in J. Mater. Chem. C, 2017, 5, 12561. The diol is an aliphatic diol. Suitable diols for glycothermal synthesis include ethylene glycol, 1,2-propanediol, 1,2-butanediol, 1,3-propanediol, and 1,4-butanediol. More preferably, the luminescent nanoparticles are obtained by the glycothermal method, wherein 1,4-butanediol is the diol solvent.

[0042] Preferably, a co-solvent is used in the alcoholothermic process. The co-solvent allows for a reduction in the size and aggregation of the nanoparticles. More preferably, the luminescent nanoparticles are obtained by the alcoholothermic process, wherein 1,4-butanediol is the diol solvent, and the process further includes a co-solvent, which is at least one selected from ethylene glycol, diethylene glycol, and polyethylene glycol 200.

[0043] (A1-x B x ) 3 (C 1-y D y ) 5 O 12 precursor materials of nanoparticles In the second embodiment, step (a) includes providing (A) 1-x B x )3(C 1-y D y )5O 12 Precursor materials for nanoparticles. A includes one or more of yttrium, lutetium, gadolinium, and lanthanum; B includes one or more rare earth elements; C includes one or more of aluminum, gallium, and scandium; D includes one or more transition metal ions; and 0≤x≤1, 0≤y≤1, and x+y>0.

[0044] The preferences of A, B, C, and D can be followed (A) 1-x B x )3(C 1-y D y )5O 12 Preferred properties of nanoparticles.

[0045] Preferably, the precursor material is obtained by precipitation. Examples of precipitation are described in PCT / EP2022 / 086309 (incorporated herein by reference) or PCT / EP2022 / 087966 (incorporated herein by reference). More preferably, the precursor material is obtained by precipitation reaction in a microjet reactor. Preferably, the precipitation process comprises contacting a first mixture comprising a solvent and salts (as applicable) comprising A, B, C and / or D with a second mixture comprising a precipitant and a solvent. The salts are preferably selected from halides, acetates, acetylacetone salts, sulfates, nitrates and / or hydrates of these substances. The solvent is preferably a polar solvent. The precipitant is preferably a base. The precursor particles obtained by precipitation can form an aggregated network. As measured by BET physisorption, the BET specific surface area of ​​the precursor particles is preferably ≥10 m². 2 / g, more preferably ≥15 m 2 / g, as measured by TEM, the D of the total aggregate particles 50 ≤100 nm.

[0046] (ii) Further providing a precursor of an oxide material, wherein the oxide material has a melting point of at least 850°C. Preferably, the oxide precursor is selected from organosilicones, silicates, aluminum salts, magnesium salts, and phosphates.

[0047] More preferably, the oxide precursor is selected from silicon salts, aluminum salts, magnesium salts, and phosphates, and the salt is selected from nitride salts or chloride salts. More preferably, the precursor is an orthosilicate, preferably tetraethyl orthosilicate (TEOS).

[0048] The oxide material has a melting point of 850°C or higher. Preferably, it has a melting point of 900°C or higher, more preferably 1200°C or higher. A high melting point allows luminescent materials or precursors containing nanoparticles to be processed, for example, by annealing, without the nanoparticles melting, sintering, or clumping together. Therefore, the melting point of the oxide material is preferably higher than the annealing temperature.

[0049] Preferably, the oxide material is selected from silicon dioxide, alumina, or phosphate. More preferably, the oxide material is selected from silicon dioxide, alumina, magnesium oxide, and phosphate. These materials exhibit good physical, chemical, and thermal stability. Preferably, the second material is silicon dioxide because it exhibits good stability. Silicon dioxide can also be easily dispersed in water and other hydrophilic solvents, making the composite luminescent particles suitable for a variety of applications. In some embodiments, the oxide material may be doped with luminescent ions.

[0050] The amount of oxide precursor used can depend on the type of luminescent particles or luminescent particle precursor, and also on the type of oxide precursor used. Typically, when using TEOS, approximately 5 μL to approximately 1 ml is used per 100 mg of particles.

[0051] (iii) Other luminescent materials In a preferred embodiment, step (a) further provides (iii) other luminescent materials, or precursors thereof, including rare-earth, s²-configuration ions, or transition metal-doped phosphor materials. This allows for the production of phosphors including (A) 1-x B x )3(C 1-y D y )5O 12 Composite particles of nanoparticles and other luminescent materials.

[0052] In this disclosure, phosphorescent materials doped with rare earth elements, s²-configured ions, or transition metals are luminescent materials, i.e., materials that emit light when exposed to certain types of radiation energy, and are doped with rare earth metals, s²-configured ions, or transition metal ions. As those skilled in the art know, doped phosphorescent materials comprise a main lattice doped with optically active ions. Rare earth metal ions are defined as described above. Transition metal ions are defined as described above, and s²-configured ions are defined as any ion having an s² electronic configuration. An example of an s²-configured ion is Ge. 2+ Pb 2+and Bi 3+ .

[0053] Preferably, the other luminescent material is doped with trivalent ions of at least one of cerium, europium, or terbium. These ions are capable of emitting light in the visible spectrum under appropriate excitation, thus making them attractive for illumination.

[0054] Preferably, the other luminescent materials are selected from oxides, fluorides, nitrides, borates, garnets, molybdates, phosphates, vanadates, chlorides, sulfides, selenides, silicates, aluminates, oxyfluorides, oxychlorides, oxynitrides, oxysulfides, oxyselenides, fluorochlorides, fluorosilicates, and fluorobromines, or combinations thereof. These materials form a lattice in which rare earth metal ions can be doped.

[0055] More preferably, the other luminescent material is selected from oxides, garnets, phosphates, vanadates, or combinations thereof. Even more preferably, the luminescent material is selected from rare earth elements, s² configuration ions, or transition metal-doped Y₃Al₅O₂. 12 Lu3Al5O 12 Tb3Al5O 12 Y₂O₃, YVPO₄, YVO₄, or LaPO₄, or combinations thereof. These luminescent materials have been found to exhibit desirable optical properties.

[0056] Preferably, (i) includes (A) 1-x B x )3(C 1-y D y )5O 12 (iii) luminescent materials or precursor materials of nanoparticles, and other luminescent materials or precursor materials including rare-earth, s²-configuration ions or transition metal-doped phosphor materials, forming individual microregions in an oxide material, wherein said microregions have a size, as measured using transmission electron microscopy (TEM), of the minimum size D of said microregions. 50 The value is ≥0.5 nm and ≤100 nm, more preferably ≥0.5 nm and ≤50 nm, and most preferably ≥0.5 nm and ≤20 nm. Preferably, the Do of the micro-region... 50 Value ≥ 0.5 nm and ≤ 100 nm. For discrete micro-regions, the D of the micro-region... 50 The preferred value is ≥0.5 nm and ≤50 nm, and the most preferred value is ≥0.5 nm and ≤20 nm. For network-like microregions, the BET specific surface area is more preferably ≥10 m². 2 / g, more preferably ≥15 m 2 / g. Therefore, the micro-region size does not include the oxide material coating. Micro-regions of this size are suitable for FRET. Such small micro-regions are desirable because they have a high specific surface area. The oxide material forms a stable matrix around the micro-regions, thereby preventing or at least greatly limiting ion exchange or quenching. Furthermore, the oxide material keeps the micro-regions in place, so that the distance between the micro-regions remains unchanged and is unaffected by post-processing.

[0057] Step (b) includes (i) (A) 1-x B x ) 3 (C 1-y D y ) 5 O 12 The luminescent material of nanoparticles and the oxide described in (ii) Precursor mixing of materials Step (b) includes mixing the luminescent material or the precursor material of (i) with the precursor of the oxide material of (ii).

[0058] In one embodiment, the mixing in step (b) is carried out by simply adding the precursor of the oxide material to the luminescent material or a dispersion of the precursor material. Preferably, the dispersion medium is a water / ethanol mixture. Preferably, the method is based on the Stöber reaction.

[0059] In another embodiment, the mixing is achieved by first preparing a water-in-oil microemulsion (in which the luminescent material is located at the core of the droplets) and then adding TEOS to the microemulsion. Examples of this method are described in Koole, R.; vanSchooneveld, MM; Hilhorst, J.; de Mello Donegá, C.; 't Hart, DC; vanBlaaderen, A.; Vanmaekelbergh, D.; Meijerink, A. Chem. Mater 2008, 20, 2503-2512.

[0060] Preferably, step b) includes stirring. This allows the luminescent material or precursor material to remain in the dispersion and ensures that the precursor of the oxide material is uniformly distributed.

[0061] Preferably, after step b) but before step c), the mixture is further stirred, for example by ultrasonic treatment. This further ensures a uniform distribution of the oxide material precursor and a good dispersion of the luminescent material.

[0062] When (iii) other luminescent materials or their precursors, including phosphor materials doped with rare earth elements, s² configuration ions, or transition metals, are provided, the distance between the luminescent micro-regions within the oxide material can be adjusted by changing method steps b) and c). This allows for adjustment depending on the material. Precise control of the interparticle spacing between the first luminescent material and other luminescent materials in the final composite luminescent particles provides control over energy transfer efficiency, thereby providing good control over the final emission spectrum color.

[0063] In one embodiment, method step (b) is performed in a single step, resulting in the formation of a single mixture. This leads to a minimum amount of distance between the micro-regions. Adjusting the distance between the different micro-regions is important because it not only allows control over the desired energy transfer (smaller distances provide higher energy transfer efficiency) but also over quenching effects (e.g., charge transfer quenching, for which greater distances result in less quenching).

[0064] In one embodiment, method step (b) includes: - The first container will contain (i) including (A) 1-x B x )3(C 1-y D y )5O 12 luminescent materials of nanoparticles or the aforementioned (A) 1-x B x )3(C 1-y D y )5O 12 The precursor material of the nanoparticles is mixed with the precursor of the oxide material described in (ii), and the other luminescent material or its precursor material described in (iii) is mixed with the precursor of the oxide material described in (ii) in a second container, and - Mix the mixture.

[0065] Mixing the luminescent material separately from the precursor of the oxide material allows for adjustment of the distance between the luminescent materials in the final particles. Therefore, this embodiment provides a moderate distance between micro-regions.

[0066] In one embodiment, method step (b) includes: b1) The first container contains (i) comprising (A) 1-x B x )3(C 1-y D y )5O 12 luminescent materials of nanoparticles or the aforementioned (A) 1-x B x )3(C 1-y Dy )5O 12 The precursor material of the nanoparticles is mixed with the precursor of the oxide material described in (ii), and the other luminescent material or its precursor material described in (iii) is mixed with the precursor of the oxide material described in (ii) in a second container. b2) To solidify at least one of the resulting mixtures at least partially. b3) Mix the at least partially cured mixture.

[0067] This results in greater distances between micro-regions.

[0068] (c) Curing the precursor of the oxide material to obtain cured particles, the cured particles comprising the... The luminescent material and the coating layer of the oxide material Step (c) includes curing the precursor of the oxide material to obtain cured particles, the cured particles comprising (i) the components comprising (A) 1-x B x )3(C 1-y D y )5O 12 luminescent materials of nanoparticles or the aforementioned (A) 1-x B x )3(C 1-y D y )5O 12 The precursor material of the nanoparticles and the coating layer of the oxide material.

[0069] Such curing can be achieved, for example, through condensation or hydrolysis. Preferably, the curing is a hydrolysis reaction. More preferably, the curing is achieved by adding an ammonia solution.

[0070] Preferably, the curing process is carried out slowly and / or under stirring. This prevents the particles from agglomerating. For example, an ammonia solution can be added dropwise under continuous stirring.

[0071] Preferably, the method further includes drying the cured particles. More preferably, the method includes drying the cured particles at a temperature of 80°C to 125°C.

[0072] Preferably, the method further includes drying the cured particles at a temperature of 80°C to 125°C, grinding the dried particles after curing step c), and / or grinding the particles after heating step (d) or (e).

[0073] Step (d) involves heating the cured particles at a first temperature for a first duration, wherein the first temperature is 800°C. or longer, wherein the first duration is 10 minutes or longer. The solidified particles are heated at a first temperature for a first duration. Heating the precursor nanoparticles can form a luminescent material. Heating the luminescent nanoparticles can eliminate crystal defects in the crystal lattice, induce and / or promote crystallinity, and remove any volatile / organic trace substances and impurities.

[0074] The first temperature is 600°C or higher. Preferably, the first temperature is 800°C or higher, more preferably 900°C or higher. Preferably, the first temperature is 1500°C or lower, more preferably 1250°C or lower. Lower temperatures are ineffective for eliminating crystal defects. Higher temperatures are impractical because oxide materials may melt or react, and require high energy consumption.

[0075] The first duration is 10 minutes or longer. Preferably, the first duration is 30 minutes or longer, more preferably 1 hour or longer. Preferably, the first duration is 8 hours or shorter, more preferably 5 hours or shorter, and most preferably 3 hours or shorter. A shorter duration may not effectively eliminate crystal defects.

[0076] Higher temperatures allow for shorter heating times, while longer heating times allow for lower temperatures.

[0077] The solidified particles are heated at a first temperature for a first duration in an atmosphere. Preferably, the atmosphere is air or an inert gas. When the mixture is heated in air, no special measures are required. The inert gas can be N2 or Ar.

[0078] (e) The cured particles are heated at a second temperature for a second time under a reducing atmosphere including carbon monoxide. The duration is long, wherein the second temperature is 500°C or higher, and wherein the second duration is 1 hour or longer. The solidified particles are heated at a second temperature for a second time in a reducing atmosphere. This step has been found to yield luminescent nanoparticles exhibiting excellent photoluminescence quantum yield and luminescence properties, as well as improved stability.

[0079] The second temperature is 700°C or higher. Preferably, the second temperature is 800°C or higher, more preferably 1000°C or higher. Preferably, the second temperature is 1400°C or lower, more preferably 1200°C or lower. In a reducing atmosphere, higher temperatures may cause the luminescent material or oxide coating to melt or react. Temperatures that are too low may be ineffective.

[0080] The second duration is 1 hour or longer. Preferably, the second duration is 8 hours or longer, more preferably 16 hours or longer, and even more preferably 24 hours or longer. Preferably, the second duration is 40 hours or shorter, more preferably 30 hours or shorter. Dividing the duration of the heating step into multiple segments may be more practical. For example, the second duration could be a total of 26 hours, heating the cured particles for 10 hours, cooling them, heating for 8 hours, cooling them, and then heating them again for 8 hours. If the carbon source in the dual-crucible apparatus is exhausted before reaching the total second duration, it may also be necessary to divide the duration of the second heating step into multiple segments.

[0081] Higher temperatures allow for shorter heating times, while longer heating times allow for lower temperatures.

[0082] Reducing atmospheres include carbon monoxide.

[0083] Heating can be performed in a reducing atmosphere using any method known to those skilled in the art. Preferably, heating in a reducing atmosphere is performed by placing the coated sample / mixture in a first crucible contained within a second crucible, which also contains a carbon source. This is also known as the "double crucible method." When the double crucible is heated, the carbon is partially oxidized to carbon monoxide.

[0084] At least partially remove the oxide material In a preferred embodiment, the method further includes at least partial removal of the oxide material. At least partial removal of the oxide material can reduce the size of the solidified particles, making them more suitable for mixing. The at least partial removal of the oxide material is preferably achieved by milling or etching, wherein the etching is preferably NaOH, NaF, or HF etching, more preferably NaOH.

[0085] Removing at least some of the oxide material can result in more separated particles and smaller particle sizes. This helps improve mixing performance.

[0086] In one embodiment, the step of at least partially removing the oxide material is performed after step (d) heating the cured particles at a first temperature for a first duration, and before step (e) heating the cured particles at a second temperature for a second duration in a reducing atmosphere.

[0087] In another embodiment, the step of at least partially removing the oxide material is performed after step (e) heating the cured particles in a reducing atmosphere at a second temperature for a second duration.

[0088] Preferably, after at least partial removal of the oxide material, the particles are heated in a reducing atmosphere at a third temperature for a third duration, wherein the third temperature is 500°C or higher, and wherein the third duration is 1 hour or longer. The reducing atmosphere is an atmosphere that prevents oxidation and contains an active reducing gas (e.g., hydrogen and carbon monoxide). Preferably, the reducing atmosphere includes carbon monoxide. Preferably, the third temperature is 700°C or higher, more preferably 800°C or higher, and even more preferably 1000°C or higher. Preferably, the third temperature is 1400°C or lower, more preferably 1200°C or lower. Preferably, the third duration is 8 hours or longer, more preferably 16 hours or longer, and even more preferably 24 hours or longer. Preferably, the third duration is 40 hours or shorter, more preferably 30 hours or shorter. Dividing the heating step into multiple segments may be more practical. For example, the third duration could be a total of 26 hours, with the cured particles heated for 10 hours, cooled, heated for 8 hours, cooled, and then heated again for 8 hours. If the carbon source in the double crucible apparatus is exhausted before the total third heating time is reached, it may be necessary to divide the duration of the third heating step into multiple segments.

[0089] Heating in a reducing atmosphere after at least partial removal of the oxide material increases the quantum yield, which may be adversely affected by the (partial) removal step.

[0090] Figure 1 B shows the particles after at least partial removal of the oxide material.

[0091] Composite luminescent particles A composite luminescent particle obtained by the method of the present invention is provided, comprising: (i) (A) 1-x B x )3(C 1-y D y )5O 12 Nanoparticles, wherein A includes one or more of yttrium, lutetium, gadolinium, and lanthanum; B includes one or more rare earth elements; C includes one or more of aluminum, gallium, and scandium; D includes one or more transition metal ions; and 0 ≤ x ≤ 1, 0 ≤ y ≤ 1, and x + y > 0; and (ii) a coating of oxide material with a melting point of 850 °C or higher.

[0092] Composite luminescent particles can also be characterized by the following features: - Photoluminescence quantum yield greater than 60%, preferably greater than 80%; - Photostability of the storage medium, such that the photoluminescence intensity after two weeks of storage in a non-inert atmosphere is at least 80% of the initial photoluminescence intensity; - Photostable, allowing operation at >0.1 W / cm².2 Under illumination, it retains at least 50% of the initial photoluminescence intensity after 10 hours, preferably at least 50% of the initial photoluminescence intensity after 15 hours.

[0093] Composite luminescent particles include (A) 1-x B x )3(C 1-y D y )5O 12 Nanoparticles, wherein A includes one or more of yttrium, lutetium, gadolinium, and lanthanum; B includes one or more rare earth elements; C includes one or more of aluminum, gallium, and scandium; D includes one or more transition metal ions; and 0≤x≤1, 0≤y≤1, and x+y>0.

[0094] Preferably, A comprises at least one selected from yttrium, lutetium, gadolinium, and lanthanum, and B comprises at least one selected from cerium, terbium, and europium. More preferably, C is aluminum, and B is cerium, europium, terbium, or a combination of terbium and europium.

[0095] The doping concentration depends on the ion type. Preferably, when B includes cerium, the molar concentration of cerium is 0.05-5% based on the combined total of A and B. Preferably, when B includes europium, the molar concentration of europium is 0.1-20% based on the combined total of A and B. Preferably, when B includes terbium, the molar concentration of terbium is 20-100% based on the combined total of A and B. Combinations of preferred doping ranges can also be applied, for example, when B includes both terbium and europium.

[0096] (A) within the composite luminescent particles 1-x B x )3(C 1-y D y )5O 12 Nanoparticles form microregions of a specific size. As measured using transmission electron microscopy (TEM), the longest diameter D of these microregions... 50 The preferred value is ≥0.5 nm and ≤100 nm, more preferably ≥0.5 nm and ≤50 nm, and most preferably ≥0.5 nm and ≤20 nm. Preferably, the Do value of the micro-region is... 50 Value ≥ 0.5 nm and ≤ 100 nm. For discrete micro-regions, the D of the micro-region... 50 The preferred value is ≥0.5 nm and ≤50 nm, and the most preferred value is ≥0.5 nm and ≤20 nm. For network-like microregions, the BET specific surface area is more preferably ≥10 m². 2 / g, more preferably ≥15 m 2 / g. Microdomains of this size are suitable for FRET. Such small microdomains are desirable because they have a high specific surface area. The oxide material forms a stable matrix around the microdomains, thereby preventing ion exchange or quenching. Furthermore, the oxide material keeps the microdomains in place, ensuring that the distance between the microdomains remains constant and is unaffected by post-processing.

[0097] The composite luminescent particles also include a coating layer of oxide material with a melting point of 850°C or higher. The oxide material forms a coating layer around the first and second luminescent materials. This protects the luminescent materials from degradation caused by factors such as humidity or high temperatures.

[0098] The oxide material has a melting point of 850°C or higher. Preferably, the melting point is 1000°C or higher, more preferably 1200°C or higher. A high melting point allows the composite luminescent particles to be treated, for example, by annealing the luminescent material, without melting or agglomeration. Therefore, the melting point of the oxide material is preferably higher than the annealing temperature.

[0099] Preferably, the oxide material is selected from silicon oxide, aluminum oxide, or phosphate. More preferably, the oxide material is selected from silicon dioxide, aluminum oxide, magnesium oxide, and phosphate. These materials have good physical, chemical, and thermal stability. Preferably, the second material is silicon dioxide because it has good stability. Silicon dioxide can also be easily dispersed in water and other hydrophilic solvents, making the composite luminescent particles suitable for a variety of applications. In some embodiments, the oxide material may be doped with luminescent ions.

[0100] Composite luminescent particles have improved properties.

[0101] The photoluminescence quantum yield of the composite luminescent particles is greater than 60%, preferably greater than 80%. The photoluminescence quantum yield is determined using the integrating sphere method, in which the number of photons absorbed and emitted by the sample relative to a reference is measured. The quantum yield is defined as the ratio of the number of photons emitted by the sample to the number of photons absorbed.

[0102] When Ce is used as a dopant, the excitation spectrum of Ce-doped luminescent nanoparticles in garnet preferably shows a peak ratio (455:380) greater than 20, measured at 455 nm and 380 nm. This differs from untreated cerium-doped aluminum garnet nanoparticles, which have a much higher excitation probability at 380 nm than annealed or bulk cerium aluminum garnet, and therefore a peak ratio much lower than 20.

[0103] Composite luminescent particles exhibit improved storage stability. This storage photostable stability ensures that the photoluminescence intensity remains at least 80% of its initial intensity after two weeks of storage in a non-inert atmosphere. Many luminescent nanoparticle materials exhibit poor storage photostable stability.

[0104] The composite luminescent particles exhibit improved photostability. Their photostability under illumination allows for a minimum of 0.1 W / cm² at a suitable excitation wavelength. 2 Under illumination, the light retains at least 50% of the initial photoluminescence intensity after 10 hours, preferably at least 50% after 15 hours. A suitable excitation wavelength refers to any wavelength that can be used to effectively excite the luminescent material.

[0105] The photostability is preferably at least 1.5 times higher, and more preferably at least 2 times higher, than that of the composite luminescent particles without the heating step. For example, if the unheated composite luminescent particles retain at least 30% of their initial photoluminescence intensity after 10 hours of illumination, then the heated composite luminescent particles have a photostability of at least 45% under illumination. The illumination is at a suitable excitation wavelength of at least 0.1 W / cm². 2 The illumination is performed at the light intensity specified. The illumination is conducted at the wavelength that excites the composite luminescent particles. For example, when the composite luminescent particles include cerium, the illumination is performed at 450 nm.

[0106] Because of the high initial photoluminescence quantum yield, the photostability under illumination can be lower than that of materials with a lower initial photoluminescence quantum yield, while the final photoluminescence quantum yield remains higher than that of such materials. Therefore, the composite luminescent particles preferably possess photostability under illumination, such that after 10 hours, the photoluminescence quantum yield is higher than 35%, preferably higher than 40%. Illumination is performed at a suitable excitation wavelength of at least 0.1 W / cm². 2 The experiment was conducted under light intensity conditions.

[0107] Preferably, as measured using a transmission electron microscope, the longest diameter D of the composite luminescent particles is... 50 The value is ≥1 nm and ≤50 µm. More preferably, as measured using a transmission electron microscope (TEM), the D 50 The particle size is ≥20 nm and ≤10 µm, with the most preferred value being ≥50 nm and ≤10 µm. Smaller particle size allows for inter-particle FRET (Fluorescence Emission Transmission), and due to the thinner oxide coating, the distance between luminescent materials is smaller. Smaller particles also have a higher specific surface area, which is desirable.

[0108] In one aspect of the invention, the composite luminescent particles include other luminescent materials. Other luminescent materials include phosphors doped with rare earth elements, s² configuration ions, or transition metals.

[0109] Preferably, the other luminescent material is doped with trivalent ions of at least one of cerium, europium, or terbium. These ions are capable of emitting light in the visible spectrum under appropriate excitation, thus making them attractive for illumination.

[0110] Preferably, the other luminescent materials are selected from oxides, fluorides, nitrides, borates, garnets, molybdates, phosphates, vanadates, chlorides, sulfides, selenides, silicates, aluminates, oxyfluorides, oxychlorides, oxynitrides, oxysulfides, oxyselenides, fluorochlorides, fluorosilicates, and fluorobromines, or combinations thereof. These materials form a lattice in which rare earth metal ions can be doped.

[0111] More preferably, the other luminescent material is selected from oxides, garnets, phosphates, vanadates, or combinations thereof. Even more preferably, the luminescent material is selected from Y3Al5O 12 Lu3Al5O 12 Tb3Al5O 12 Y₂O₃, YVPO₄, YVO₄, or LaPO₄, or combinations thereof. These luminescent materials have been found to exhibit desirable optical properties.

[0112] Other luminescent materials also form microregions within the composite luminescent particles. As measured using transmission electron microscopy (TEM), the minimum size of these microregions is D... 50 The preferred value is ≥0.5 nm and ≤100 nm, more preferably ≥0.5 nm and ≤50 nm, and most preferably ≥0.5 nm and ≤20 nm. Preferably, the Do value of the micro-region is... 50 The micro-area size is ≥0.5 nm and ≤100 nm, more preferably ≥0.5 nm and ≤50 nm, and most preferably ≥0.5 nm and ≤20 nm. Therefore, the size of the micro-area does not include the oxide material coating. Micro-areas of this size are suitable for FRET. Such small micro-areas are desirable because they have a high specific surface area.

[0113] Luminescent particles can be obtained by a method including at least partially removing the oxide material. Also provided are luminescent particles that can be obtained by a method including at least partially removing the oxide material.

[0114] The luminescent particles include (i) at least one (A) 1-x B x )3(C 1-y D y )5O 12 Nanoparticles, wherein A includes one or more of yttrium, lutetium, gadolinium, and lanthanum; B includes one or more rare earth elements; C includes one or more of aluminum, gallium, and scandium; D includes one or more transition metal ions, and 0≤x≤1, 0≤y≤1, and x+y>0.

[0115] The composite luminescent particles include (A) 1-x B x )3(C 1-y Dy )5O 12 Nanoparticles, wherein A includes one or more of yttrium, lutetium, gadolinium, and lanthanum; B includes one or more rare earth elements; C includes one or more of aluminum, gallium, and scandium; D includes one or more transition metal ions; and 0≤x≤1, 0≤y≤1, and x+y>0.

[0116] Preferably, A comprises at least one of yttrium, lutetium, gadolinium, and lanthanum, and B comprises at least one of cerium, terbium, and europium. More preferably, C is aluminum, and B is cerium, europium, terbium, or a combination of terbium and europium.

[0117] The doping concentration depends on the ion type. Preferably, when B includes cerium, the molar concentration of cerium is 0.05-5% based on the combined total of A and B. Preferably, when B includes europium, the molar concentration of europium is 0.1-20% based on the combined total of A and B. Preferably, when B includes terbium, the molar concentration of terbium is 20-100% based on the combined total of A and B. Combinations of preferred doping ranges can also be applied, for example, when B includes both terbium and europium.

[0118] The luminescent particles have D 50 Value. Preferably, the longest diameter D 50 The wavelength is ≥0.5 nm and ≤100 nm, more preferably ≥0.5 nm and ≤50 nm, and most preferably ≥0.5 nm and ≤20 nm. For network-like luminescent particles, the BET specific surface area is preferably ≥10 m². 2 / g, more preferably ≥15 m 2 / g. Microdomains of this size are suitable for FRET. Such small microdomains are desirable because they have a high specific surface area.

[0119] Preferably, the luminescent particles include (ii) a coating layer of oxide material with a melting point of 850°C or higher, wherein the thickness of the coating layer is greater than 0 nm and less than 5 nm. This thickness of coating layer allows the luminescent particles to have physical and chemical stability associated with the coating layer while maintaining a small size.

[0120] The oxide material has a melting point of 850°C or higher. Preferably, the melting point is 1000°C or higher, more preferably 1200°C or higher. A high melting point allows the luminescent material to be treated, for example, by annealing, without the luminescent particles melting or agglomerating. Therefore, the melting point of the oxide material is preferably higher than the annealing temperature.

[0121] Preferably, the oxide material is selected from silica, alumina, or phosphate. More preferably, the oxide material is selected from silica, alumina, magnesia, and phosphate. These materials have good physical, chemical, and thermal stability. Preferably, the second material is silica because this material exhibits good stability. Silica can also be easily dispersed in water and other hydrophilic solvents, making the composite luminescent particles suitable for various applications. In certain embodiments, the oxide material may be doped with luminescent ions.

[0122] Preferably, the luminescent particles can be characterized by the following features: - A photoluminescence quantum yield greater than 60%, preferably greater than 80%; - Storage photo stability such that the photoluminescence intensity after storage for two weeks in a non-inert atmosphere is at least 80% of the initial photoluminescence intensity; and - Photo stability under illumination such that at an excitation wavelength of >0.1 W / cm 2 under illumination, at least 50% of the initial photoluminescence intensity is retained after 10 hours, preferably at least 50% of the initial photoluminescence intensity is retained after 15 hours.

[0123] These improved properties are the same as those of the composite luminescent particles.

[0124] In another embodiment, a luminescent particle is provided, which is preferably obtained by a method including at least partially removing the oxide material, wherein the luminescent particle comprises the following materials: (i) at least one (A 1-x B x )3(C 1-y D y )5O 12 nanoparticle, wherein A comprises yttrium, preferably consisting of yttrium; B comprises cerium and terbium, preferably consisting of cerium and terbium; C comprises aluminum, preferably consisting of aluminum; D comprises one or more transition metal ions; and 0 < x ≤ 1, 0 ≤ y ≤ 1, and x + y > 0.

[0125] This defines a material of the YAG:Ce,Tb type. The molar concentration of cerium is 0.05 - 5% based on the combined total of A and B. The molar concentration of terbium is 20 - 100% based on the combined total of A and B, preferably 55 - 95%, more preferably 60 - 90%.

[0126] The particle size of the luminescent particles of this preferred embodiment is such that the D 50 value of the longest diameter ≥0.5 nm and ≤50 nm, more preferably ≥0.5 nm and ≤30 nm, even more preferably ≥0.5 nm and ≤20 nm.

[0127] Surprisingly, it has been found that the luminescent particles of a further preferred embodiment exhibit increased photostability compared to YAG:Ce particles of similar size that do not contain Tb or contain Tb but at concentrations outside the range. Stabilization is absent when the Tb doping concentration is below 20%. Thermal quenching may result in lower overall quantum yield when the Tb doping concentration is above the preferred concentrations of 95% and 90%.

[0128] Preferably, the luminescent particles described herein can also be characterized by the following features: - Photoluminescence quantum yield greater than 60%, preferably greater than 80%; - Storage photostability, such that the photoluminescence intensity after two weeks of storage in a non-inert atmosphere is at least 80% of the initial photoluminescence intensity; and - Photostability under illumination, allowing for >0.1 W / cm² at appropriate excitation wavelengths. 2 Under illumination, it retains at least 50% of the initial photoluminescence intensity after 10 hours, preferably at least 50% of the initial photoluminescence intensity after 15 hours.

[0129] Luminescent Composition The present invention provides a luminescent composition. The luminescent composition includes a first luminescent material and a second luminescent material, wherein at least one of the first luminescent material and the second luminescent material includes composite luminescent particles according to the present invention.

[0130] Preferably, the first luminescent material is capable of emitting light within a first wavelength range, the second luminescent material is capable of absorbing light within a second wavelength range, and has an emission spectrum that at least partially overlaps with one or more excitation bands of the first luminescent material.

[0131] More preferably, the first luminescent material and the second luminescent material are arranged to allow nonradiative energy transfer from the second luminescent material to the first luminescent material.

[0132] In one embodiment, the luminescent composition includes a first luminescent material coated with an oxide material as particles, and a second luminescent material coated with an oxide material as particles. Because of the oxide materials coating the first and second luminescent materials, the luminescent particles can be better mixed, resulting in a more uniform luminescent composition. This composition, as... Figure 1 As shown in “c”.

[0133] In one embodiment, the particles coated with the oxide material include only one of the first luminescent material or the second luminescent material. In this case, preferably, as measured using a transmission electron microscope (TEM), the minimum size D of the other luminescent material is... 50The preferred wavelength value is ≥0.5 nm and ≤100 nm, more preferably ≥0.5 nm and ≤50 nm, and most preferably ≥0.5 nm and ≤20 nm. Preferably, the D of another luminescent material... 50 The value is ≥0.5 nm and ≤100 nm, more preferably ≥0.5 nm and ≤50 nm, and most preferably ≥0.5 nm and ≤20 nm. In another embodiment, another luminescent material is provided as the bulk material, and the coated particles are disposed on the bulk luminescent material. In the context of this document, the term "bulk" specifically refers to and / or includes sizes larger than nanometers, such as diameters greater than 100 nm, which include micrometer-scale dimensions.

[0134] In one embodiment, both the first luminescent material and the second luminescent material are included in the composite particles of the present invention.

[0135] First luminescent material and second luminescent material Preferably, the first luminescent material is capable of emitting light within a first wavelength range, the second luminescent material is capable of absorbing light within a second wavelength range, and has an emission spectrum that at least partially overlaps with one or more excitation bands of the first luminescent material. The following applies to all embodiments conforming to the above description.

[0136] The first luminescent material is capable of emitting light within a first wavelength range. Those skilled in the art will understand that the first luminescent material functions as an emitting material in the luminescent composition according to the invention. The first wavelength range can be any wavelength range of interest. Preferred wavelength ranges will be described below.

[0137] The second luminescent material is capable of absorbing light within a second wavelength range. Those skilled in the art will understand that the second luminescent material acts as a sensitizer in the luminescent composition according to the invention. The second wavelength range can be any wavelength range of interest. Preferred wavelength ranges will be described below.

[0138] When the second luminescent material is excited by light within a second wavelength range, its emission spectrum at least partially overlaps with one or more excitation bands of the first luminescent material. Those skilled in the art are fully capable of determining this spectral overlap based on spectra known in the art or through conventional experiments (e.g., disclosed in WO2020 / 053429).

[0139] Preferably, the emission spectrum of the second material overlaps with one or more excitation bands of the first material in the wavelength range of blue (440 to 510 nm), green (510 to 560 nm), or yellow (560 to 580 nm).

[0140] Preferably, the first and second luminescent materials are arranged to allow nonradiative energy transfer (sometimes also called fluorescence resonance energy transfer, FRET) from the second luminescent material (sensitizer) to the first luminescent material (emitter material). Typically, this involves close proximity between the first and second luminescent materials, for example, a distance of approximately 0.5 nm to approximately 20 nm. Those skilled in the art will readily understand how nonradiative energy transfer can be achieved. For example, this is described in WO2018 / 167266, the contents of which are incorporated herein by reference. Those skilled in the art will understand that nonradiative energy transfer involves the nonradiative transfer of energy from an excited sensitizer to acceptor (or emitter) ions in the luminescent material. This is verified by the fact that increased selective excitation of the sensitizer material leads to increased emission of emitter ions from the luminescent material. The nonradiative energy transfer of interest can originate from Förster-type or Dexter-type energy transfer. Those skilled in the art will recognize that, since the resonant energy transfer is inversely proportional to the sixth power of the inter-ion distance (in the case of Förster-type energy transfer) or exponentially proportional to the distance (in the case of Dexter-type energy transfer), arrangements that allow for non-radiative energy transfer can be achieved through the appropriate design of the effective distance between the sensitizer material and the luminescent ions in the luminescent material.

[0141] Those skilled in the art will understand that the first and second materials must be close together for FRET to occur.

[0142] First luminescent material The first luminescent material is capable of emitting light within a first wavelength range. The first wavelength range can be any wavelength range of interest.

[0143] 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 under appropriate excitation, and the term green luminescent material refers to a material having one or more emission bands between 510 nm and 560 nm under appropriate excitation. Providing a red or green luminescent material may be desirable for color rendering purposes. According to another optional aspect of the invention, the first luminescent material is a material having one or more emission bands between 700 and 1400 nm (IR-A), between 580 and 600 nm (amber and / or orange), between 560 and 580 nm (yellow), between 480 and 510 nm (cyan), between 440 and 480 nm (blue), between 400 and 440 nm (violet), between 315 and 400 nm (UV-A), and / or between 280 and 315 nm (UV-B) under appropriate excitation.

[0144] The primary luminescent material preferably comprises a phosphor material doped with rare earth elements, s² configuration ions, or transition metals. The fluorescent material can 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+ ) and their combinations; examples of suitable transition metal-doped phosphor materials include: BaMgAl 14 O 23 :Mn 2+ Mg(Al,Ga)₂O₄:Mn 2+ Zn2SiO4:Mn 2+ K2SiF6:Mn 4+ MgF2.GeO2:Mn 4+ and their combinations.

[0145] As previously stated, the first luminescent material may include composite luminescent particles according to the present invention.

[0146] Phosphor materials are currently available on the open market or can be synthesized, for example, as shown in [Riwotzki, K.; Meyssamy, H.; Kornowski, A.; Haase, MJ Phys. Chem. B]. . As described in 2000, 104, 2824-2828.

[0147] As is known to those skilled in the art, phosphor materials doped with rare earth, s2 configuration ions or transition metals include a main lattice doped with optically active ions.

[0148] The first luminescent material can have any suitable host lattice. For example, the host lattice can be selected from oxides, fluorides, nitrides, borates, garnets, molybdates, phosphates, vanadates, chlorides, sulfides, selenides, silicates, aluminates, oxyfluorides, oxychlorides, oxynitrides, oxysulfides, oxyselenides, fluorochlorides, fluorosilicates, and fluorobromines, or combinations thereof, or other inorganic host materials in which optically active ions can be incorporated.

[0149] Preferably, the main lattice of the first luminescent material is an oxide, phosphate, vanadate, or a combination thereof, more preferably selected from Y3Al5O 12 ("YAG"), Lu3Al5O 12 (“LuAG”), Y2O3, YVPO4, YVO4, or LaPO4, or combinations thereof. Preferably, the preferred main lattice of the first luminescent material is doped with one or more of the following: Eu. 3+ 、Tb 3+ Mn 2+ and Mn 4+ These ions provide good emission characteristics, such as strong emission bands and / or emission bands located in the red or green portions of the visible spectrum.

[0150] In Eu 3+ In the case of doping, the first luminescent material may, for example, have a doped main lattice with a doping ratio of at least about 1%, more preferably about 5% to about 80%. In Tb 3+ In the case of doping, the first luminescent material may, for example, have a Tb doping ratio of at least about 10%, more preferably about 30% to about 80%. 3+ The doped main lattice. In Mn 4+ In the case of doping, the first luminescent material can, for example, have a main lattice with a doping ratio of about 0.1-30%, most preferably about 1-10%. In Mn... 2+ In the case of doping, the first luminescent material may, for example, have a doped main lattice with a doping ratio of about 0.1-30%, most preferably about 1-10%.

[0151] In an exemplary embodiment, the first luminescent material is selected from (Ca,Sr)Ga2O6:Eu 3+ (or Tb) 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 (fake-ball aragonite):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+ Cs3Ge3O9:Eu 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)₂: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:Eu3+ (or Tb) 3+ ), La2O2(SO4):Eu 3+ (or Tb) 3+ ), 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+ ), LaMgB5O 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 Tb) 3+ 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:Eu 3+ (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:Eu 3+ (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+ ), SrB6O 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 Tb) 3+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 mixture thereof.

[0152] Those skilled in the art will understand that the symbol Eu 3+ (or:Tb) 3+ Or:Ce 3+ Or: Mn 2+ Or: Mn 4+ The main lattice is doped with Eu. 3+ (or doped with Tb) 3+ or doped with Ce 3+ or doped with Mn 2+ Or doped with Mn 4+ ).

[0153] Second luminescent material The second luminescent material preferably comprises composite luminescent particles according to the present invention, which include (A) 1-x B x )3(C 1-y D y )5O 12 Nanoparticles. In such compositions, B is preferably cerium and / or terbium.

[0154] As discussed, the first luminescent material may include composite luminescent particles according to the invention. In compositions in which the first luminescent material includes composite luminescent particles according to the invention, the second luminescent material is preferably as described below.

[0155] Any suitable inorganic luminescent material can be used as a secondary luminescent material. The secondary material is capable of absorbing light within a secondary wavelength range. The secondary wavelength can be any wavelength range of interest.

[0156] Preferably, the second luminescent material has one or more excitation bands in the wavelength range of 380 to 580 nm. More preferably, the second luminescent material has one or more excitation bands in the UV-A (315 to 400 nm), violet (400 to 440 nm), blue (440 to 490 nm), or green (510 to 560 nm) wavelength range, most preferably in the blue (440 to 490 nm) wavelength range. (Al,In,Ga)N-based LEDs provide efficient "pump" light generation in the violet to blue wavelength range (approximately 400 nm to approximately 490 nm). An example of a blue excitable material is CaAlSiN3:Eu 2+ and Y3Al5O 12 :Ce 3+ .

[0157] In other aspects of the invention, the second luminescent material is a material having one or more excitation bands between 700 and 1400 nm (IR-A), between 580 and 600 nm (amber and / or orange), between 560 and 580 nm (yellow), between 510 and 560 nm (green), between 480 and 510 nm (cyan), between 440 and 480 nm (blue), between 400 and 440 nm (violet), between 315 and 400 nm (UV-A), and / or between 280 and 315 nm (UV-B).

[0158] In another preferred embodiment, the main lattice of the second luminescent material is garnet, fluoride, silicate, phosphate, or nitride, more preferably selected from Y3Al5O 12 ("YAG"), Lu3Al5O 12 (“LuAG”), LaPO4, MgF2, CaF2, Sr2SiO4, Ba2SiO4, Ca2MgSi2O7, LiSrPO4, CaAlSiN3, or combinations thereof. Preferably, the second luminescent material has a preferred principal lattice doped with a material selected from Eu. 2+ Pb 2+ Bi 3+ and Ce 3+ One or more ions, more preferably Eu 2+or Ce 3+ With Tb 3+ Combination, optimal choice Ce 3+ With Tb 3+ combination.

[0159] Preferably, the main lattice of the second luminescent material or its precursor is garnet, such as Y3Al5O. 12 ("YAG") or Lu3Al5O 12 (“LuAG”) or combinations thereof. Most preferably, the main lattice is selected from Y3Al5O. 12 ("YAG") or Lu3Al5O 12 (“LuAG”) or combinations thereof, with dopants including Ce 3+ Optional with Tb 3+ combination.

[0160] Preferably, in Ce 3+ In the case of doping, the second luminescent material has a main lattice with a doping level of about 0.05-5%, more preferably 0.1-4%.

[0161] Preferably, the first luminescent material comprises Y₂O₃:RE, wherein RE is europium(III), and the second luminescent material comprises composite luminescent particles according to the invention, wherein B is cerium and / or terbium. More preferably, the Y₂O₃:RE material is provided as nanoparticles.

[0162] In a preferred embodiment, the first luminescent material comprises rare-earth metal-doped nanoparticles, wherein the rare-earth metal is europium(III), and the second luminescent material comprises composite luminescent particles according to the present invention, which include (A... 1-x B x )3(C 1-y D y )5O 12 Nanoparticles, wherein B is cerium(III) and / or terbium(III).

[0163] In a preferred embodiment, the luminescent composite particles of the present invention comprise both a first luminescent material and a second luminescent material. Preferably, the first and second luminescent materials form separate microregions within the oxide material, wherein the microregions have a size, as measured using a transmission electron microscope (TEM), where the minimum size of the microregion is D. 50 The value is ≥0.5 nm and ≤100 nm, more preferably ≥0.5 nm and ≤50 nm, and most preferably ≥0.5 nm and ≤20 nm. Preferably, the Do of the micro-region... 50The micro-area size is ≥0.5 nm and ≤100 nm, more preferably ≥0.5 nm and ≤50 nm, and most preferably ≥0.5 nm and ≤20 nm. Therefore, the micro-area size does not include the oxide material coating layer. Micro-areas of this size are suitable for FRET. Such small micro-areas are desirable because they have a high specific surface area. The oxide material forms a stable matrix around the micro-areas, thereby preventing ion exchange or quenching. Furthermore, the oxide material keeps the micro-areas in place, ensuring that the distance between micro-areas remains constant and is unaffected by post-processing.

[0164] The present invention also relates to a light-emitting device comprising the composite light-emitting particles of the present invention or the light-emitting composition of the present invention. Preferably, the light-emitting device further comprises an excitation source for a light-emitting material, such as an excitation source for a second light-emitting material. Preferably, the excitation source is a UV-A, violet, or blue light-emitting material that emits light toward the light-emitting material at wavelengths of 315-400 nm (UV-A), 400-440 nm (violet), or 440-480 nm (blue), more preferably 430-465 nm.

[0165] The light-emitting device can be composed of a blue LED, with composite light-emitting particles or a light-emitting composition according to the invention deposited on top of the LED chip. The composite light-emitting particles according to the invention can be incorporated into a polymer or silicone paste deposited on the blue LED chip and subsequently cured.

[0166] The present invention also relates to a lighting system comprising a light-emitting device according to the invention. Preferably, the lighting system is selected from lamps or illuminators, office lighting systems, home application systems, shop lighting systems, residential lighting systems, accent lighting systems, spotlighting systems, theater lighting systems, fiber optic application systems, projection systems, self-emissive display systems, pixelated display systems, segmented display systems, warning sign systems, medical lighting application systems, indicator sign systems, decorative lighting systems, portable systems, automotive applications, and greenhouse lighting systems.

[0167] This invention also relates to the use of luminescent compositions according to the invention or luminescent materials comprising composite luminescent particles according to the invention as taggants. A taggant is a marker added to a material to allow for testing in various forms. The total excitation / emission spectra of the composite luminescent particles and / or luminescent compositions according to the invention can have unique characteristics compared to conventional methods, making them suitable for use as taggants in anti-counterfeiting applications. For example, US7667828B discloses a tagging system comprising multiple types of taggants that are different from each other.

[0168] The invention is also defined in the following clauses, which are not restrictive and may be combined with the prior descriptive paragraphs: 1. A method for providing composite luminescent particles, comprising: (a) Provide (i) Includes (A) 1-x B x )3(C 1-y D y )5O 12 The luminescent nanoparticle material, wherein A comprises one or more of yttrium, lutetium, gadolinium, and lanthanum; B comprises one or more rare earth elements; C comprises one or more of aluminum, gallium, and scandium; D comprises one or more transition metal ions; and wherein 0 ≤ x ≤ 1, 0 ≤ y ≤ 1, and x + y > 0; and (ii) further provides a precursor of an oxide material, wherein the oxide material has a melting point of at least 850 °C; (b) including (i) (A) 1-x B x )3(C 1-y D y )5O 12 The luminescent nanoparticles are mixed with the precursor of the oxide material described in (ii); (c) Curing the precursor of the oxide material to obtain cured particles, the cured particles comprising the luminescent material and the coating layer of the oxide material; (d) Heating the cured particles at a first temperature for a first duration, wherein the first temperature is 600°C or higher, and wherein the first duration is 10 minutes or longer; and (e) The cured particles are heated at a second temperature for a second duration in a reducing atmosphere including carbon monoxide, wherein the second temperature is 700°C or higher, and wherein the second duration is 1 hour or longer. Preferably, the (A) 1-x B x )3(C 1-y D y )5O 12 Nanoparticles are obtained by a solvothermal method, and more preferably by an alcoholothermal method.

[0169] 2. A method for obtaining composite luminescent particles, comprising: (a) Provide (i) (A 1-x B x )3(C 1-y D y )5O 12The precursor material for nanoparticles, wherein A comprises one or more of yttrium, lutetium, gadolinium, and lanthanum; B comprises one or more rare earth elements; C comprises one or more of aluminum, gallium, and scandium; D comprises one or more transition metal ions; and wherein 0 ≤ x ≤ 1, 0 ≤ y ≤ 1, and x + y > 0; and (ii) further provides a precursor of an oxide material, wherein the oxide material has a melting point of at least 850 °C; (b) Mix the precursor material described in (i) with the precursor of the oxide material described in (ii); (c) Curing the precursor of the oxide material to obtain cured particles, the cured particles comprising the precursor material and a coating layer of the oxide material; (d) Heating the cured particles at a first temperature for a first duration, wherein the first temperature is 600°C or higher, and wherein the first duration is 10 minutes or longer; and (e) The cured particles are heated at a second temperature for a second duration in a reducing atmosphere including carbon monoxide, wherein the second temperature is 700°C or higher, and wherein the second duration is 1 hour or longer. The precursor material is preferably obtained by precipitation.

[0170] 3. The method according to Clause 1 or 2, wherein: B includes one or more of cerium, terbium, and europium. Preferably, B includes cerium and C includes aluminum.

[0171] 4. The method according to any one of clauses 1-3, wherein: - The first temperature is 800°C or higher, preferably 900°C or higher, and more preferably 1500°C or lower, more preferably 1250°C or lower; - The first duration is 10 minutes or longer, preferably 1 hour or longer, and more preferably 8 hours or shorter, more preferably 5 hours or shorter, and most preferably 3 hours or shorter; and / or - The mixture is heated at a first temperature for a first duration in an atmosphere, wherein the atmosphere is air or an inert gas.

[0172] 5. The method according to any one of clauses 1-4, wherein: - The reducing atmosphere includes carbon monoxide; - The second temperature is 900°C or higher, and preferably 1150°C or lower; - The second duration is 8 hours or longer, preferably 16 hours or longer, more preferably 24 hours or longer, and preferably 40 hours or shorter, more preferably 30 hours or shorter.

[0173] 6. The method according to Clause 5, wherein heating in a reducing atmosphere is carried out by placing the mixture in a first crucible, the first crucible being contained in a closed second crucible, the second crucible also containing a carbon source.

[0174] 7. The method according to any one of the preceding clauses, wherein the precursor of the oxide material is selected from organosilicones, silicates, aluminum salts, phosphates and magnesium salts, preferably wherein the salt is selected from nitride salts or halide salts, and / or the precursor is an orthosilicate, and / or step c) includes a hydrolysis reaction, preferably wherein the oxide material is silicon dioxide, and step c) includes the addition of ammonia to cure the precursor of the oxide material.

[0175] 8. The method according to any one of the preceding clauses, wherein in step (a), (iii) other luminescent materials or precursors thereof, including rare earth, s2 configuration ion or transition metal doped phosphor materials, are also provided; 9. The method according to Clause 8, wherein the doped phosphor material comprises oxides, fluorides, nitrides, borates, garnets, molybdates, phosphates, vanadates, chlorides, sulfides, selenides, silicates, aluminates, oxyfluorides, oxychlorides, oxynitrides, oxysulfides, oxyselenides, fluorochlorides, fluorosilicates, and fluorobromines, or combinations thereof. Preferably, it is selected from oxides, garnets, phosphates, vanadates, or combinations thereof. More preferably, selected from Y3Al5O 12 Lu3Al5O 12 Y₂O₃, YVPO₄, YVO₄ or LaPO₄ or combinations thereof.

[0176] 10. The method according to Clause 8 or 9, wherein step b) is carried out in a single step, such that a single mixture is formed.

[0177] 11. The method according to clause 8 or 9, wherein method step b) comprises: b1) The first container contains (i) comprising (A) 1-x B x )3(C 1-y D y )5O 12 luminescent materials of nanoparticles or the aforementioned (A) 1-x B x )3(C 1-y D y )5O 12The precursor material of the nanoparticles is mixed with the precursor of the oxide material described in (ii), and the other luminescent material or its precursor material described in (iii) is mixed with the precursor of the oxide material described in (ii) in a second container; b2) Optionally, at least one of the resulting mixtures is at least partially cured; and b3) Mix the mixture, which is optionally at least partially cured.

[0178] 12. The method according to any one of the preceding clauses further includes at least partial removal of the oxide material, preferably by grinding or etching, wherein the etching is preferably NaOH etching; preferably, it further includes heating the particles at a third temperature for a third duration in a reducing atmosphere after at least partial removal of the oxide material, wherein the third temperature is 500°C or higher, and wherein the third duration is 1 hour or longer.

[0179] 13. A composite luminescent particle obtained by any one of the preceding clauses, said composite luminescent particle comprising: (i) (A) 1-x B x )3(C 1-y D y )5O 12 Nanoparticles, wherein A comprises one or more of yttrium, lutetium, gadolinium, and lanthanum; B comprises one or more rare earth elements; C comprises one or more of aluminum, gallium, and scandium; D comprises one or more transition metal ions, and 0 ≤ x ≤ 1, 0 ≤ y ≤ 1, and x + y > 0; and (ii) a coating layer of oxide material with a melting point of 850°C or higher; the composite luminescent particles have: - Photoluminescence quantum yield greater than 60%, preferably greater than 80%; - Photostability of the storage medium, such that the photoluminescence intensity after two weeks of storage in a non-inert atmosphere is at least 80% of the initial photoluminescence intensity; - Photostability under illumination allows for >0.1 W / cm² at suitable excitation wavelengths. 2 Under illumination, it retains at least 50% of its initial photoluminescence intensity after 10 hours, preferably at least 50% of its initial photoluminescence intensity after 15 hours; and - Preferably, when B includes cerium, the peak ratio in the excitation spectrum is greater than 20 (between 455 nm and 380 nm).

[0180] 14. A composite luminescent particle, which can be obtained by means of the method according to Clause 12, The composite luminescent particles include: (i) at least one (A) 1-x B x )3(C1-y D y )5O 12 nanoparticles, wherein A comprises one or more of yttrium, lutetium, gadolinium, and lanthanum; B comprises one or more rare earth elements, C comprises one or more of aluminum, gallium, and scandium, D comprises one or more transition metal ions, and 0 ≤ x ≤ 1, 0 ≤ y ≤ 1, and x + y > 0; preferably, and (ii) a coating layer of an oxide material having a melting point of 850 °C or higher, wherein the thickness of the coating layer is greater than 0 nm and less than 5 nm; Preferably, wherein the composite luminescent particles have: - a photoluminescence quantum yield greater than 60%, preferably greater than 80%; - storage photostability such that the photoluminescence intensity after storage for two weeks in a non-inert atmosphere is at least 80% of the initial photoluminescence intensity; - photostability under illumination such that at >0.1 W / cm 2 under illumination, at least 50% of the initial photoluminescence intensity is retained after 10 hours, preferably at least 50% of the initial photoluminescence intensity is retained after 15 hours; and - Preferably, when B comprises cerium, a peak ratio greater than 20 in the excitation spectrum (between 455 nm and 380 nm).

[0181] 15. The composite luminescent particles according to clause 14 or the luminescent particles according to clause 15, wherein A comprises at least one selected from yttrium and lutetium, B comprises at least one of cerium, terbium, and europium, preferably, wherein C is aluminum and B is cerium, europium, terbium, or a combination of terbium and europium: - When B comprises cerium, the molar concentration of cerium is 0.05 - 5% based on the combined total of A and B; - When B comprises europium, the molar concentration of europium is 0.1 - 20% based on the combined total of A and B; and / or - Preferably, when B comprises terbium, the molar concentration of terbium is 20 - 100% based on the combined total of A and B.

[0182] 16. A luminescent particle, preferably obtainable by the method according to clause 12, wherein the luminescent particle comprises the following materials: (i) at least one (A 1-x B x )3(C 1-y D y )5O 12 nanoparticles, wherein A comprises yttrium, preferably consisting of yttrium; B comprises cerium and terbium, preferably consisting of cerium and terbium; C comprises aluminum, preferably consisting of aluminum; D comprises one or more transition metal ions; and 0 < x ≤ 1, 0 ≤ y ≤ 1, and x + y > 0, wherein: - The molar concentration of cerium is 0.05-5% based on the combined total of A and B; - The molar concentration of terbium is 20-100% based on the combined total amount of A and B, preferably 55-95%, more preferably 60-90%; - The optimal particle size of the luminescent particles ensures that the longest diameter D 50 The value is ≥0.5 nm and ≤50 nm, more preferably ≥0.5 nm and ≤30 nm, and even more preferably ≥0.5 nm and ≤20 nm; and 17. The light-emitting particles according to Clause 16, wherein the light-emitting particles have: - Photoluminescence quantum yield greater than 60%, preferably greater than 80%; - Photostability of the storage medium, such that the photoluminescence intensity after two weeks of storage in a non-inert atmosphere is at least 80% of the initial photoluminescence intensity; - Photostability under illumination allows for >0.1 W / cm² at suitable excitation wavelengths. 2 Under illumination, it retains at least 50% of its initial photoluminescence intensity after 10 hours, preferably at least 50% of its initial photoluminescence intensity after 15 hours; and - Peak ratio greater than 20 in the excitation spectrum (between 455 nm and 380 nm).

[0183] 18. A luminescent composition comprising a first luminescent material and a second luminescent material, wherein at least one of the first luminescent material and the second luminescent material comprises composite luminescent particles according to any one of clauses 13-17. Preferably, the first luminescent material is capable of emitting light in a first wavelength range, the second luminescent material is capable of absorbing light in a second wavelength range, and has an emission spectrum that at least partially overlaps with one or more excitation bands of the first luminescent material. More preferably, the first and second luminescent materials are arranged relative to each other to allow nonradiative energy transfer from the second luminescent material to the first luminescent material. More preferably, both the first luminescent material and the second luminescent material include composite luminescent particles or luminescent particles according to any one of clauses 13-17.

[0184] 19. A luminescent composition obtained by any one of claims 8-12, said luminescent composition comprising: (i) a first luminescent material comprising (A 1-x B x )3(C 1-y D y )5O 12(ii) nanoparticles; and (iii) a second luminescent material comprising nanoparticles of phosphor materials doped with rare earth, s2-configuration ions, or transition metals; Preferably, the first luminescent material is capable of emitting light in a first wavelength range, the second luminescent material is capable of absorbing light in a second wavelength range, and has an emission spectrum that at least partially overlaps with one or more excitation bands of the first luminescent material. More preferably, the first and second luminescent materials are arranged to allow nonradiative energy transfer from the second luminescent material to the first luminescent material.

[0185] 20. The composite luminescent particle or luminescent particle according to any one of Clauses 13-17, or the luminescent composition according to Clauses 18 or 19, characterized in that the composite luminescent particle, luminescent particle, or luminescent composition comprises at least trace amounts of oxide material, preferably wherein the oxide material is selected from silicon oxide, aluminum oxide, phosphate, or magnesium oxide.

[0186] 21. A light-emitting device comprising composite light-emitting particles or light-emitting particles as described in Clauses 13-17, or light-emitting compositions as described in Clauses 18-20, and purple and / or blue light-emitting semiconductor materials.

[0187] 22. A system comprising a light-emitting composition according to any one of clauses 18-20 and / or a light-emitting device according to clause 21, said system being one or more of the following: a. Office lighting system b. Home application systems c. Shop lighting system d. Home lighting systems e. Accent lighting system f. Spotlighting system g. Theater lighting system h. Fiber Optic Application Systems i. Projection system j. Self-emissive display system k. Pixelated display system l. Segmented display system m. Warning sign system n. Medical lighting application system o. Indication and signage system p. Decorative lighting system q. Portable systems r. Automotive applications s. Greenhouse lighting system t. Display backlight u. Transmitting display v. Miniature LED 23. Use of the composite luminescent particles, luminescent particles or luminescent compositions according to any one of Clauses 13-20 as tracers, for example, for anti-counterfeiting applications.

[0188] Example: Nanoparticle Synthesis Methods Co-precipitation synthesis of YAG:Ce precursor: A YAG:Ce (0.5%) precursor was synthesized via coprecipitation. In a container, stoichiometric amounts of the metal nitrate salt hydrate were dissolved in water. For a yield of 20 g, the yttrium and cerium salt precursors (34.5 g and 0.15 g, respectively) were calculated and dissolved in 300 ml of deionized water. In another container, the corresponding stoichiometric amounts of the aluminum salt (56.3 g) were calculated and dissolved in 300 ml of deionized water. The two solutions were mixed and stirred using a magnetic stirrer. A precipitant solution was prepared by dissolving 52.1 g of ammonium bicarbonate (AHC) in 528 ml of deionized water. 132 ml of ammonia solution (32% ammonia) was added to this solution, and the mixture was stirred using a magnetic stirrer. The coprecipitation reaction was carried out using a microjets reactor (MJR), where the metal salt and precipitant were forced to react within a microreactor (300 μm chamber size). The flow rates of both the precursor and precipitant were maintained at 40 ml / min, and the final precipitate was collected. The precipitate was then washed several times with water and dried. The specific surface area of ​​the precursor nanoparticles was measured using the BET physisorption method, and it ranged from 130 to 180 m². 2 / g range.

[0189] The nano-YAG precursor sample is amorphous and therefore does not exhibit emission.

[0190] Solventothermic synthesis of YAG:Ce YAG:Ce (0.5%) nanoparticles were prepared by an alcoholothermic method according to the method disclosed in (J. Mater. Chem. C, 2017, 5, 12561). This method produces individual nanoparticles with a size <10 nm. Here, a metal acetate hydrate and an alkoxide are used and mixed in 1,4-butanediol and diethylene glycol (volume ratio 85:15). 200 ml of solvent is used for a yield of 10 g. The mixture is then placed in an autoclave and heated to 300-350 °C with stirring for 1-2 hours. After cooling, the sample is removed and washed several times with ethanol and acetone to obtain YAG:Ce nanoparticles.

[0191] Comparative Experiments A and B: Annealing of Nano-YAG:Ce under Unprotected Matrix Conditions In Comparative Experiment A, the nano-YAG precursor obtained using the co-precipitation method described above was annealed in air at 1025°C for 2 hours, and then annealed in a reducing atmosphere at 1025°C for 24 hours. In these experiments, the reducing atmosphere was created by placing the sample crucible inside a larger, covered crucible containing activated carbon. Due to the limited oxygen, this double-crucible setup generates a CO atmosphere at high temperatures and provides the reducing atmosphere.

[0192] In Comparative Experiment B, as described above, the YAG:Ce nanoparticles obtained by the solvothermal method were annealed in the same manner.

[0193] Figure 2 TEM images of nanoparticles obtained by coprecipitation after calcination are shown. The specific surface area of ​​the annealed nanoparticles was measured using the BET physisorption method. For the coprecipitated YAG nanoparticles, the average BET specific surface area is approximately 20 m². 2 / g. Figure 3 TEM images of nanoparticles obtained by a solvothermal method are shown. The nanoparticles are relatively sintered, and an aggregated morphology is observed.

[0194] The PL performance is improved after the heating step. The maximum PLQY for either is approximately 85%. Figure 6 The reflectance spectrum (thin dashed line) of comparative experiment A is shown.

[0195] Comparative Experiment CD: Annealing of nano-YAG:Ce in a matrix The nano-YAG precursor obtained by co-precipitation and the nanoparticles obtained by solvothermal method were subjected to salt encapsulation: a 0.5 M K₂SO₄ aqueous solution was prepared. YAG:Ce nanoparticles or nano-YAG precursor particles were mixed with the K₂SO₄ solution to obtain a dispersion with a YAG (precursor):K₂SO₄ weight ratio of 1:10. Mixing was enhanced by sonication in an ultrasonic bath for 30 minutes. Acetone was added, with a volume ratio of acetone:reaction mixture of 1:8. The mixture was centrifuged, washed with acetone, and the precipitate was dried.

[0196] In comparative experiment C, the nano-YAG precursor particles obtained by the co-precipitation method were salt-encapsulated. One sample was annealed in air at 1025°C for 2 hours, followed by annealing in a reducing atmosphere including carbon monoxide at 800°C for 8 hours. Another sample was annealed in air at 1025°C for 2 hours only. The nanoparticles were washed several times with water to remove K2SO4. The luminescence properties of the samples annealed in single air and those annealed in two steps (air-CO) were measured. The single-annealed sample exhibited a broad yellow emission, while the two-step annealed sample showed improved emission characteristics. The PLQY of the two-step annealed sample increased to approximately 80-85%. Sintering of the matrix was avoided during the heat treatment.

[0197] In comparative experiment D, YAG:Ce nanoparticles obtained by solvothermal method were salt-encapsulated. One sample was annealed in air at 1025°C for 2 hours, followed by annealing at 800°C for 8 hours in a reducing atmosphere containing carbon monoxide. The other sample was annealed in air at 1025°C for 2 hours only. The nanoparticles were washed several times with water to remove K2SO4.

[0198] The luminescence properties of samples annealed in a single air process and those annealed in a two-step air-CO process were measured. The PLQY of the samples annealed in a single air process was approximately 70%, which increased to 75-80% after the two-step annealing. Sintering of the matrix was avoided during the heat treatment process.

[0199] Comparative Experiment EF: Silica Encapsulation, Single Air Annealing The nano-YAG precursor obtained by co-precipitation and the nanoparticles obtained by solvothermal method were encapsulated with silica: In Comparative Experiment E, nano-YAG precursor particles obtained by co-precipitation were encapsulated with silica. Approximately 200 mg of YAG:Ce precursor was dispersed in 10 ml of water and 10 ml of ethanol. The mixture was then sonicated for 10 minutes. 0.020 ml of tetraethyl orthosilicate (TEOS), a silica precursor, was added dropwise with continuous stirring. The mixture was then stirred for 24 hours and cured with ammonia. Finally, the mixture was heated to 105 °C until completely dry.

[0200] In Comparative Experiment F, nano-YAG particles obtained by a solvothermal method were encapsulated with silica. Approximately 200 mg of YAG:Ce nanoparticles were dispersed in 10 mL of water and 10 mL of ethanol. The mixture was sonicated for 10 minutes. Under continuous stirring, 0.320 mL of tetraethyl orthosilicate (TEOS), a silica precursor, was added dropwise. The mixture was then stirred for 24 hours and cured with ammonia. Finally, the mixture was heated to 105 °C until completely dry.

[0201] The sample was annealed in air at 1025°C for 2 hours. The sample was then ground into a fine powder.

[0202] The luminescence properties of samples subjected to single air annealing were measured. Samples obtained by the co-precipitation method exhibited approximately 85% PLQY, and their reflectance spectra are as follows: Figure 7 As shown (thin dashed line). The sample obtained by the solvothermal method has approximately 80% PLQY, and its reflectance spectrum is as follows. Figure 8 As shown (thin dashed line).

[0203] Comparative Experiment G: Silica encapsulation, single CO annealing YAG:Ce nanoparticles obtained by solvothermal method were encapsulated in silica as in Comparative Experiment F. The samples were annealed at 1025 °C for 24 hours in a reducing atmosphere including carbon monoxide. The samples were then ground into fine powder.

[0204] The luminescence properties of the sample annealed with a single CO layer were measured. PLQY < 90%. The sample exhibited aggregated particles within the silica matrix.

[0205] Example 1: Silica encapsulation, two-step annealing, co-precipitation synthesis YAG:Ce precursor particles were obtained using the co-precipitation method detailed above. Following the method described in Comparative Experiment E, the precursor particles were encapsulated in silica.

[0206] The sample was annealed in air at 1025°C for 2 hours, and then annealed at 1025°C for 24 hours in a reducing atmosphere containing carbon monoxide. The annealed sample was then ground into a fine powder.

[0207] Luminescent properties were measured. Compared with comparative experiments A, C, and E, both emission intensity and PLQY were improved. PLQY > 95%.

[0208] Compared to two-step annealed nanoparticles without a protective matrix (Comparative Experiment 1), the sample showed improvement due to Ce. 3+ The resulting increase in absorption, and the decrease in absorption below 400 nm ( Figure 6 This effect can be attributed to the surface coating of silica, which helps reduce surface defects and Ce oxidation. Therefore, overall, silica contributes to surface defect passivation and improves Ce oxidation. 3+ / Ce 4+ balance.

[0209] Comparing the reflectance spectra of Experiment E and Example 1 ( Figure 7 This indicates that, compared to comparative experiment E with air annealing alone, two-step calcination increases Ce in the blue light spectrum. 3+ Absorption. Furthermore, the second annealing step reduces UV absorption below 400 nm, which is due to dangling bonds and Ce... 4+ The combined effect of reducing amorphous silica.

[0210] TEM images show relatively small and few aggregated particles ( Figure 4 The specific surface area of ​​the annealed nanoparticles was measured using the BET physical adsorption method, with an average BET specific surface area of ​​30-50 m². 2 Within the range of / g.

[0211] Example 2: Silica encapsulation, two-step annealing, solvothermal synthesis YAG:Ce nanoparticles were obtained using the solvothermal method detailed above. As in Comparative Experiment F, the nanoparticles were encapsulated in silica.

[0212] The sample was annealed in air at 1025°C for 2 hours, and then annealed at 1025°C for 24 hours in a reducing atmosphere containing carbon monoxide. The annealed sample was then ground to obtain a fine powder.

[0213] Luminescence performance was measured. Compared with comparative experiments B, D, F, and G, both emission intensity and PLQY were improved. PLQY > 95%.

[0214] Comparing the reflectance spectra of Experiment F and Example 2 ( Figure 8 This indicates that, compared to comparative experiment F with air annealing alone, two-step calcination increases Ce in the blue light spectrum. 3+ Absorption. Furthermore, the second annealing step reduces UV absorption below 400 nm, which is due to dangling bonds and Ce... 4+ The combined effect of reducing amorphous silica.

[0215] TEM images show relatively small and few aggregated particles ( Figure 5 ).

[0216] Example 3: Silica encapsulation, two-step annealing and alkaline etching, solvothermal synthesis YAG:Ce nanoparticles were obtained using the solvothermal method detailed above. As in Comparative Experiment F, the nanoparticles were encapsulated in silica.

[0217] The sample was annealed in air at 1025°C for 2 hours, and then annealed at 1025°C for 24 hours in a reducing atmosphere containing carbon monoxide. The annealed sample was then ground to obtain a fine powder.

[0218] The obtained sample was then etched with 2 M NaOH solution. 200 mg of sample was added to 10 mL of 2 M NaOH solution and stirred for 24 hours. The sample was then washed with water and centrifuged; this washing process was repeated twice. The obtained sample was then dried at 105 °C.

[0219] Luminescence properties were measured. Compared to Example 2, emission intensity and PLQY decreased. PLQY < 70%. Specific surface area measurements by nitrogen physisorption showed that after etching with 2 M NaOH solution for 24 hours, the specific surface area decreased from 50 m² / s² of the sample before etching. 2 / g increased to 80 m 2 / g. The increase in specific surface area indicates a decrease in particle size. TEM image ( Figure 9 The image shows a single nanoparticle after etching.

[0220] Example 4: Silica encapsulation, two-step annealing and alkaline etching followed by re-annealing at 800°C, solvothermal process. synthesis YAG:Ce nanoparticles were obtained using the solvothermal method detailed above. As in Comparative Experiment F, the nanoparticles were encapsulated in silica.

[0221] The sample was annealed in air at 1025°C for 2 hours, and then annealed at 1025°C for 24 hours in a reducing atmosphere containing carbon monoxide. The annealed sample was then ground to obtain a fine powder.

[0222] The obtained sample was then etched with 2 M NaOH solution. For this, 200 mg of annealed silica-coated nano-YAG was added to 10 mL of 2 M NaOH solution and stirred for 24 hours. The sample was then washed with water and centrifuged, with the washing process repeated twice. The obtained sample was then dried at 105 °C. The dried powder was then annealed again at 800 °C for 8 hours in a reducing atmosphere.

[0223] Luminescence properties were measured. Compared to Example 3, both emission intensity and PLQY were improved. PLQY > 85%. Specific surface area measurements by nitrogen physical adsorption showed that the specific surface area of ​​the re-annealed sample was 77 m². 2 / g. This value is slightly lower than 80 μg of the etched sample. 2 The specific surface area per g indicates a slight change in densification, but clearly shows that the particle size is smaller than before etching. TEM image ( Figure 10 The image shows the morphology of the nanoparticles after re-annealing. Example 5: Increased photostability of Ce,Tb-co-doped nano-YAG YAG:Ce,Tb nanoparticles with 0.5% Ce and different amounts of Tb doping (0%, 15%, 20%, 50%, and 65%) were prepared according to the same method as in Example 4. All nanoparticles have a density of 20-30 nm. 50 .

[0224] Nanoparticles at 1 W / mm 2 The light was applied, and the change in photoluminescence intensity over time was recorded. The results are as follows: Figure 11 As shown. The top curve corresponds to 65% Tb, the second highest corresponds to 50% Tb, the middle curve corresponds to 20% Tb, the second lowest curve corresponds to 15% Tb, and the bottom curve corresponds to the 0% Tb doped YAG:0.5% Csssse sample.

[0225] It can be observed that compared to 15% Tb, 20% Tb already provides some improvement in photostability, as evidenced by a tendency for intensity to stabilize. However, only at 65% Tb does the intensity remain above 95% of the original intensity.

[0226] Example 6: Long-term photostability in LEDs compared to bulk YAG YAG:Ce,Tb nanoparticles with 0.5% Ce and 75% Tb doping were prepared using the same method as in Example 4, and they have a density of approximately 20-30 nm. 50 Additionally, using the method of Example 4, a sample with 0.5% Ce and D was prepared. 50 The YAG:Ce nanoparticles are approximately 20-30 nm in size.

[0227] In addition, the commercial ontology YAG:Ce was used as a comparison.

[0228] YAG:Ce(,Tb) samples were applied to a medium-power GaN LED (driven at 240 mA and emitting at approximately 465 nm), and the intensity variation over time was measured (up to 250 hours).

[0229] The results are as follows Figure 12 As shown. The curve below corresponds to nanoparticles with 0% Tb doping. The performance of bulk YAG:Ce and nanoparticles with 75% Tb doping is similar, except that the bulk YAG sample exhibits a more drastic loss of initial strength.

Claims

1. A method for providing composite luminescent particles, comprising: (a) Provide (i) Includes (A) 1-x B x )3(C 1-y D y )5O 12 The luminescent nanoparticle material, wherein A comprises one or more of yttrium, lutetium, gadolinium, and lanthanum; B comprises one or more rare earth elements; C comprises one or more of aluminum, gallium, and scandium; D comprises one or more transition metal ions; and wherein 0 ≤ x ≤ 1, 0 ≤ y ≤ 1, and x + y > 0; and (ii) further provides a precursor of an oxide material, wherein the oxide material has a melting point of at least 850 °C; (b) including (i) (A) 1-x B x )3(C 1-y D y )5O 12 The luminescent nanoparticles are mixed with the precursor of the oxide material described in (ii); (c) Curing the precursor of the oxide material to obtain cured particles, the cured particles comprising the luminescent material and the coating layer of the oxide material; (d) Heating the cured particles at a first temperature for a first duration, wherein the first temperature is 600°C or higher, and wherein the first duration is 10 minutes or longer; and (e) The cured particles are heated at a second temperature for a second duration in a reducing atmosphere including carbon monoxide, wherein the second temperature is 700°C or higher, and wherein the second duration is 1 hour or longer. Preferably, the (A) 1-x B x )3(C 1-y D y )5O 12 Nanoparticles are obtained by a solvothermal method, and more preferably by an alcoholothermal method.

2. A method for obtaining composite luminescent particles, comprising: (a) Provide (i) (A 1-x B x )3(C 1-y D y )5O 12 The precursor material for nanoparticles, wherein A comprises one or more of yttrium, lutetium, gadolinium, and lanthanum; B comprises one or more rare earth elements; C comprises one or more of aluminum, gallium, and scandium; D comprises one or more transition metal ions; and wherein 0 ≤ x ≤ 1, 0 ≤ y ≤ 1, and x + y > 0; and (ii) further provides a precursor of an oxide material, wherein the oxide material has a melting point of at least 850 °C; (b) The (A) mentioned in (i) 1-x B x )3(C 1-y D y )5O 12 The precursor material is mixed with the precursor of the oxide material described in (ii); (c) Curing the precursor of the oxide material to obtain cured particles, the cured particles comprising the (A) 1- x B x )3(C 1-y D y )5O 12 The precursor material, and the coating layer of the oxide material; (d) Heating the cured particles at a first temperature for a first duration, wherein the first temperature is 800°C or higher, and the first duration is 10 minutes or longer; and (e) The cured particles are heated at a second temperature for a second duration in a reducing atmosphere including carbon monoxide, wherein the second temperature is 700°C or higher, and wherein the second duration is 1 hour or longer. The precursor material is preferably obtained by precipitation.

3. The method according to claim 1 or 2, wherein: B includes one or more of cerium, terbium, and europium. Preferably, B includes cerium and C includes aluminum.

4. The method according to any one of claims 1-3, wherein: - The first temperature is 800°C or higher, preferably 900°C or higher, and more preferably 1500°C or lower, more preferably 1250°C or lower; - The first duration is 10 minutes or longer, preferably 1 hour or longer, and more preferably 8 hours or shorter, more preferably 5 hours or shorter, and most preferably 3 hours or shorter; and / or - The mixture is heated at a first temperature for a first duration in an atmosphere, wherein the atmosphere is air or an inert gas.

5. The method according to any one of claims 1-4, wherein: - The second temperature is 750°C or higher, and preferably 1150°C or lower; - The second duration is 8 hours or longer, preferably 16 hours or longer, more preferably 24 hours or longer, and preferably 40 hours or shorter, more preferably 30 hours or shorter.

6. The method of claim 5, wherein heating in a reducing atmosphere is carried out by placing the mixture in a first crucible, the first crucible being contained in a closed second crucible, the second crucible also containing a carbon source.

7. The method according to any one of the preceding claims, wherein the precursor of the oxide material is selected from organosilicones, silicates, aluminum salts, phosphates and magnesium salts, preferably wherein the salt is selected from nitride salts or halide salts, and / or the precursor is an orthosilicate, and / or step c) includes a hydrolysis reaction, preferably wherein the oxide material is silicon dioxide, and step c) includes adding ammonia to cure the precursor of the oxide material.

8. The method according to any one of the preceding claims, wherein in step (a), (iii) other luminescent materials or precursors thereof comprising rare earth, s2 configuration ion or transition metal doped phosphor materials are also provided; Preferably, the doped phosphor material comprises oxides, fluorides, nitrides, borates, garnets, molybdates, phosphates, vanadates, chlorides, sulfides, selenides, silicates, aluminates, oxyfluorides, oxychlorides, oxynitrides, oxysulfides, oxyselenides, fluorochlorides, fluorosilicates, and fluorobromines, or combinations thereof. More preferably, it is selected from oxides, garnets, phosphates, vanadates, or combinations thereof. Most preferably, it is selected from Y3Al5O 12 Lu3Al5O 12 Y₂O₃, YVPO₄, YVO₄ or LaPO₄ or combinations thereof.

9. The method of claim 9, wherein step b) is performed in a single step, such that a single mixture is formed, or wherein method step b) comprises: b1) The first container contains (i) comprising (A) 1-x B x )3(C 1-y D y )5O 12 luminescent materials of nanoparticles or the aforementioned (A) 1- x B x )3(C 1-y D y )5O 12 The precursor material of the nanoparticles is mixed with the precursor of the oxide material described in (ii), and the other luminescent material or its precursor material described in (iii) is mixed with the precursor of the oxide material described in (ii) in a second container; b2) Optionally, at least one of the resulting mixtures is at least partially cured; and b3) Mix the mixture, which is optionally at least partially cured.

10. The method according to any one of the preceding claims further comprises at least partially removing the oxide material, preferably by grinding or etching, wherein the etching is preferably NaOH etching; preferably, it further comprises, after at least partially removing the oxide material, heating the particles at a third temperature for a third duration in a reducing atmosphere, wherein the third temperature is 500°C or higher, and wherein the third duration is 1 hour or longer.

11. A composite luminescent particle, obtained by the method of any one of the preceding claims, the composite luminescent particle comprising: (i) (A) 1-x B x )3(C 1-y D y )5O 12 Nanoparticles, wherein A comprises one or more of yttrium, lutetium, gadolinium, and lanthanum; B comprises one or more rare earth elements; C comprises one or more of aluminum, gallium, and scandium; D comprises one or more transition metal ions, and 0 ≤ x ≤ 1, 0 ≤ y ≤ 1, and x + y > 0; and (ii) a coating layer of oxide material with a melting point of 850°C or higher; the composite luminescent particles have: - Photoluminescence quantum yield greater than 60%, preferably greater than 80%; - Storage photostability, such that the photoluminescence intensity after two weeks of storage in a non-inert atmosphere is at least 80% of the initial photoluminescence intensity; - Photostability under illumination allows for >0.1 W / cm² at suitable excitation wavelengths. 2 Under illumination, it retains at least 50% of the initial photoluminescence intensity after 10 hours, preferably at least 50% of the initial photoluminescence intensity after 15 hours; and - When B includes cerium, the peak ratio in the excitation spectrum is greater than 20 (between 455 nm and 380 nm).

12. A composite luminescent particle, which can be obtained by the method according to claim 10, said composite luminescent particle comprising: (i) (A) 1-x B x )3(C 1-y D y )5O 12 Nanoparticles, wherein A comprises one or more of yttrium, lutetium, gadolinium, and lanthanum; B comprises one or more rare earth elements; C comprises one or more of aluminum, gallium, and scandium; D comprises one or more transition metal ions, and 0 ≤ x ≤ 1, 0 ≤ y ≤ 1, and x + y > 0; preferably, and (ii) a coating layer of oxide material with a melting point of 850°C or higher, wherein the thickness of the coating layer is greater than 0 nm and less than 5 nm; Preferably, the composite luminescent particles have: - Photoluminescence quantum yield greater than 60%, preferably greater than 80%; - Storage photostability, such that the photoluminescence intensity after two weeks of storage in a non-inert atmosphere is at least 80% of the initial photoluminescence intensity; - Photostability under illumination allows for >0.1 W / cm² at suitable excitation wavelengths. 2 Under illumination, it retains at least 50% of its initial photoluminescence intensity after 10 hours, preferably at least 50% of its initial photoluminescence intensity after 15 hours; and - Preferably, when B includes cerium, the peak ratio in the excitation spectrum is greater than 20 (between 455 nm and 380 nm).

13. The composite luminescent particle according to claim 11 or 12, wherein A comprises at least one selected from yttrium and lutetium, and B comprises at least one selected from cerium, terbium, and europium; preferably, wherein C is aluminum, and B is cerium, europium, terbium, or a combination of terbium and europium. - When B includes cerium, the molar concentration of cerium is 0.05-5% based on the combined total of A and B; - When B includes europium, the molar concentration of europium is 0.1-20% based on the combined total of A and B; and / or - Preferably, when B includes terbium, the molar concentration of terbium is 20-100% based on the combined total of A and B.

14. A luminescent particle, preferably obtainable by the method according to claim 10, wherein the luminescent particle comprises the following materials: (i) at least one (A 1-x B x )3(C 1-y D y )5O 12 nanoparticle, wherein A comprises yttrium, preferably consisting of yttrium; B comprises cerium and terbium, preferably consisting of cerium and terbium; C comprises aluminum, preferably consisting of aluminum; D comprises one or more transition metal ions; and 0 < x ≤ 1, 0 ≤ y ≤ 1, and x + y > 0, in: - The molar concentration of cerium is 0.05-5% based on the combined total of A and B; - The molar concentration of terbium is 20-100% based on the combined total amount of A and B, preferably 55-95%, more preferably 60-90%; - The particle size of the luminescent particles is preferably such that the longest diameter D 50 The value is ≥0.5 nm and ≤50 nm, more preferably ≥0.5 nm and ≤30 nm, even more preferably ≥0.5 nm and ≤20 nm; and.

15. The light-emitting particles according to claim 14, wherein the light-emitting particles have: - Photoluminescence quantum yield greater than 60%, preferably greater than 80%; - Storage photostability, such that the photoluminescence intensity after two weeks of storage in a non-inert atmosphere is at least 80% of the initial photoluminescence intensity; - Photostability under illumination allows for >0.1 W / cm² at suitable excitation wavelengths. 2 Under illumination, it retains at least 50% of its initial photoluminescence intensity after 10 hours, preferably at least 50% of its initial photoluminescence intensity after 15 hours; and - Peak ratio greater than 20 in the excitation spectrum (between 455 nm and 380 nm).

16. A luminescent composition comprising a first luminescent material and a second luminescent material, wherein at least one of the first luminescent material and the second luminescent material comprises composite luminescent particles according to any one of claims 11-13, or luminescent particles according to any one of claims 14-15. Preferably, the first luminescent material is capable of emitting light within a first wavelength range, and the second luminescent material is capable of absorbing light within a second wavelength range, and has an emission spectrum that at least partially overlaps with one or more excitation bands of the first luminescent material. More preferably, the first and second luminescent materials are arranged to allow nonradiative energy transfer from the second luminescent material to the first luminescent material. More preferably, both the first luminescent material and the second luminescent material comprise composite luminescent particles selected from any one of claims 11-13, or luminescent particles selected from any one of claims 14-15.

17. A luminescent composition obtained by the method according to any one of claims 9-10, said luminescent composition comprising: (i) A first luminescent material, comprising (A 1-x B x )3(C 1-y D y )5O 12 (ii) nanoparticles; and (iii) a second luminescent material comprising nanoparticles of phosphor materials doped with rare earth, s2-configuration ions, or transition metals; Preferably, the first luminescent material is capable of emitting light in a first wavelength range, the second luminescent material is capable of absorbing light in a second wavelength range, and has an emission spectrum that at least partially overlaps with one or more excitation bands of the first luminescent material. More preferably, the first luminescent material and the second luminescent material are arranged to allow nonradiative energy transfer from the second luminescent material to the first luminescent material.

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