Preparation method and application of sub-micron size cerium-doped yttrium aluminum garnet powder material

Abstract

The application relates to a preparation method and application of a sub-micron-sized cerium-doped yttrium aluminum garnet powder material, and the preparation method comprises the following steps: mixing yttrium salt, aluminum salt, cerium salt and a solvent to obtain a metal ion salt solution; mixing the metal ion salt solution with a high-molecular polymer, and performing heating reaction to obtain a precursor powder material; and performing calcination on the precursor powder material to obtain the sub-micron-sized cerium-doped yttrium aluminum garnet powder material; and the mixed solvent comprises an alcohol organic solvent and water. The application adopts a hydrothermal alcohol solvent synthesis method, uses a mixed solvent formed by mixing an alcohol organic solvent and water, controls the nucleation and growth of a yttrium aluminum garnet precursor, and obtains the sub-micron-sized cerium-doped yttrium aluminum garnet powder material with a near-spherical morphology, a narrow particle size distribution and uniform morphology after high-temperature calcination, the size of the sub-micron-sized cerium-doped yttrium aluminum garnet powder material is adjustable in a wide range from 70nm to 1000nm, and the sub-micron-sized cerium-doped yttrium aluminum garnet powder material has high luminous efficiency.

Description

Technical Field

[0001] This invention relates to the field of fluorescent materials technology, and in particular to a method for preparing and applying submicron-sized cerium-doped yttrium aluminum garnet powder. Background Technology

[0002] Yttrium aluminum garnet (chemical formula Y3Al5O) 12 YAG (Yellow Aggregate) crystals have a cubic crystal structure and excellent physicochemical stability, making them an excellent optical matrix material. 3+ Doped yttrium aluminum garnet phosphors exhibit excellent luminescent properties, with an optimal excitation spectrum peak at 450 nm and an optimal emission spectrum located at a broad yellow peak at 540 nm. Building upon the development of blue LED chips (indium gallium nitride), its 450 nm blue emission spectrum effectively matches the excitation spectrum of YAG, making it the most commonly used combination for white LEDs to form cool white light for lighting. This combination offers advantages such as energy saving, high efficiency, and environmental friendliness.

[0003] Due to the poor thermal conductivity of yttrium aluminum garnet (YAGA) phosphors, heat accumulation occurs under high-power outdoor lighting conditions, severely hindering their further application. YAGA transparent ceramics can compensate for the insufficient thermal conductivity of powder materials, enabling applications in high-power scenarios. 3+ Doped yttrium aluminum garnet (YA garnet) single crystals and transparent ceramics can be used in scintillation luminescence, and are key materials for high-energy X-ray imaging. However, YA garnet single crystals are difficult to grow and expensive, hindering large-scale use. Transparent YA garnet ceramics, prepared from powder, are competitive alternatives to these single crystals, potentially replacing them in high-power luminescence and laser luminescence applications. High-quality powder is essential for the preparation of transparent ceramics. Currently, the preparation of high-quality Ce... 3+ Using doped yttrium aluminum garnet powder to sinter into transparent ceramics is a pain point and a challenge in the industry.

[0004] Currently, high-temperature solid-state synthesis, gas-phase synthesis, and liquid-phase synthesis are the main methods for preparing yttrium aluminum garnet (YAG) powder. High-temperature solid-state synthesis is a traditional method for YAG preparation, using metal oxides or carbonates in a specific ratio, calcined at high temperature to obtain Ce. 3+ Doped YAG powder. High-temperature solid-state synthesis methods require high calcination temperatures, resulting in larger powder sizes, typically above 10 μm, and sometimes reaching 50 μm. Such large-sized YAG:Ce 3+Powder materials are themselves fluorescent materials with excellent luminescence properties, but their sintering performance is low, making them difficult to use as raw materials for further sintering into transparent ceramics. YAG powders prepared by gas-phase synthesis methods are small in size, usually below tens of nanometers, and suffer from severe agglomeration, which is not conducive to the sintering of transparent ceramics.

[0005] Precipitation is a solution-based synthesis method that uses precipitants such as ammonia or carbonates to form a precipitate of metal ions in a stoichiometric ratio, which is then calcined to obtain YAG powder. However, rare earth ions precipitate very quickly under precipitant conditions, rapidly forming small particles. These small particles then aggregate to form larger secondary particles with a loose structure, resulting in inhomogeneous morphology, a wide size distribution, and a tendency to sinter into lumps during subsequent calcination. Therefore, precipitation is difficult to use to obtain uniformly dispersed YAG powder with controllable size.

[0006] Hydrothermal and solvothermal synthesis methods can yield YAG powders with relatively uniform morphology and size. However, current hydrothermal and solvothermal methods often only produce powders of one size, and it is difficult to control the powder size over a wide range by adjusting the synthesis parameters. The literature (Ceramics International 38 (2012) 235–242) reported the synthesis of 500 nm uniform YAG powders using a hydrothermal method under ammonia-assisted conditions. Under alkaline conditions, small particles aggregated to form a uniform cubic morphology. However, by adjusting the reaction conditions, it is not only difficult to obtain powders of other sizes, but also difficult to maintain the original morphology uniformity.

[0007] Therefore, given the application of YAG transparent ceramics, it is urgent and much needed by the industry to develop cerium-doped YAG powder with adjustable size and uniform morphology and corresponding synthesis methods. Summary of the Invention

[0008] To address the aforementioned technical problems, the present invention aims to provide a method for preparing and applying submicron-sized cerium-doped yttrium aluminum garnet (YAG) powder materials. This invention utilizes an aldol reaction to precipitate metal ions in a specific ratio, forming a precursor with uniform size and morphology. The precursor is then calcined to obtain the cerium-doped YAG phase powder material. The Ce2-doped YAG powder material prepared by this invention... 3+ The morphology of the doped YAG powder is nearly spherical, and its size can be controlled within the range of 70 nm to 1000 nm, with a narrow size distribution. It also exhibits good luminescence properties, with an excitation peak at 450 nm, an emission peak at 540 nm, and a luminescence quantum efficiency of over 85%.

[0009] To achieve this objective, the present invention adopts the following technical solution:

[0010] In a first aspect, the present invention provides a method for preparing submicron-sized cerium-doped yttrium aluminum garnet powder materials, the preparation method comprising the following steps:

[0011] A metal ion salt solution is obtained by mixing yttrium salt, aluminum salt, cerium salt and solvent; the metal ion salt solution is then mixed with a polymer and reacted by heating to obtain a precursor powder material.

[0012] The precursor powder material is calcined to obtain the submicron-sized cerium-doped yttrium aluminum garnet powder material;

[0013] The mixed solvent includes alcoholic organic solvents and water.

[0014] This invention utilizes alcohols as solvents and reactants. Under heating conditions, alcohols exhibit high reactivity and can control the reaction rate, thereby allowing yttrium and aluminum ions to precipitate in stoichiometric ratio. This achieves uniform dispersion of yttrium and aluminum at the atomic scale, which facilitates the formation of the yttrium aluminum garnet phase through subsequent low-temperature calcination without phase separation.

[0015] In traditional precipitation methods, yttrium and aluminum are typically co-precipitated directly using a precipitant. Because rare earth ions precipitate very rapidly under precipitant conditions, they quickly form small particles. These small particles then aggregate to form larger secondary particles with a loose structure, resulting in uneven morphology and a very wide size distribution. The method of this invention, under aldolothermic conditions, can balance the precipitation reaction of metal ions and the particle growth process, allowing the small particles after the precipitation reaction to continue growing on existing particles, obtaining a product with controllable size. The reaction is similar to the Stobber reaction process, yielding cerium-doped yttrium aluminum garnet powder material with uniform size and morphology and a narrow particle size distribution.

[0016] This invention employs a hydrothermal alcohol-solvent thermal synthesis method, using a mixed solvent formed by mixing alcoholic organic solvents and water. By controlling the alcohol content and reaction temperature, the reaction rate is regulated, thereby controlling the nucleation and growth of yttrium aluminum garnet precursors. Controllable synthesis of precursor particles is achieved by regulating the slow growth of the precursor. The basic principle of this reaction is the in-situ generation of a base (OH-) through an alcoholic thermal reaction. — In this method, the in-situ generated alkali reacts with metal ions to form metal oxide monomers. The formation rate of the monomers is controlled by the reaction rate, which in turn controls the nucleation and growth process. This is significantly different from traditional methods that require the addition of an additional alkali, which cannot control the reaction rate between the alkali and metal ions or the subsequent products. This preparation method solves the problems of difficulty in controlling particle size, poor uniformity of particle size and morphology, and easy agglomeration in existing technologies. In addition, the preparation method provided by this invention has the characteristics of stable process, high yield, and strong operability, and can be mass-produced.

[0017] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. The technical objectives and beneficial effects of the present invention can be better achieved and realized through the following preferred technical solutions.

[0018] Preferably, the volume ratio of alcohol organic solvent to water in the mixed solvent is (0.1-2):1, for example, it can be 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1 or 2:1, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0019] Preferably, the alcoholic organic solvent includes any one or a combination of at least two of methanol, ethanol, ethylene glycol, isopropanol, butanol, diethylene glycol, or glycerol. Typical but non-limiting combinations include combinations of methanol and ethanol, ethylene glycol and isopropanol, butanol and diethylene glycol, isopropanol, butanol, and glycerol, methanol, ethylene glycol, and isopropanol, ethanol, ethylene glycol, and isopropanol, and ethylene glycol, isopropanol, butanol, diethylene glycol, and glycerol. Preferably, it is methanol, ethanol, or ethylene glycol.

[0020] Preferably, the concentration of yttrium salt in the metal ion salt solution is 0.1 mol / L-1.0 mol / L, for example, it can be 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L or 1.0 mol / L, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 0.3 mol / L-0.6 mol / L.

[0021] This invention further controls the concentration of yttrium salt in the metal ion salt solution to 0.1 mol / L-1.0 mol / L, regulates the reaction rate by controlling the reaction temperature, and modulates the nucleation and subsequent growth processes. This ensures that the precursor, after nucleation and growth, forms a near-spherical morphology with good size uniformity, narrow particle size distribution, and no particle agglomeration. The near-spherical morphology of the precursor remains unchanged after calcination. The calcination process controls the internal transformation of the particles into the garnet phase, while preventing particle agglomeration, thus maintaining the dispersed state of the precursor.

[0022] Preferably, the molar ratio of yttrium salt, aluminum salt, and cerium salt in the metal ion salt solution is (3-2.5) mol: 5 mol: (0-0.5) mol, for example, it can be 2.99 mol: 5 mol: 0.01 mol, 2.98 mol: 5 mol: 0.02 mol, 2.97 mol: 5 mol: 0.03 mol, 2.96 mol: 5 mol: 0.04 mol, 2.95 mol: 5 mol: 0.05 mol, 2.94 mol: 5 mol: 0.06 mol, or 2.90 mol: 5 mol The possible values ​​are 0.1 mol, 2.85 mol:5 mol:0.15 mol, 2.8 mol:5 mol:0.2 mol, 2.75 mol:5 mol:0.25 mol, 2.7 mol:5 mol:0.3 mol, 2.65 mol:5 mol:0.35 mol, 2.6 mol:5 mol:0.4 mol, 2.55 mol:5 mol:0.45 mol, or 2.5 mol:5 mol:0.5 mol, but are not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0023] Preferably, the cerium salt comprises any one or a combination of at least two of cerium nitrate, cerium ammonium nitrate, cerium sulfate, or cerium chloride. Typical but non-limiting combinations include combinations of cerium nitrate and cerium ammonium nitrate, combinations of cerium ammonium nitrate and cerium sulfate, combinations of cerium sulfate and cerium chloride, combinations of cerium nitrate, cerium sulfate, and cerium chloride, combinations of cerium ammonium nitrate, cerium sulfate, and cerium chloride, and combinations of cerium nitrate, cerium ammonium nitrate, cerium sulfate, and cerium chloride. Cerium nitrate is preferred.

[0024] Preferably, the aluminum salt includes any one or a combination of at least two of aluminum nitrate, aluminum sulfate, or aluminum chloride. Typical but non-limiting combinations include combinations of aluminum nitrate and aluminum sulfate, combinations of aluminum sulfate and aluminum chloride, combinations of aluminum nitrate and aluminum chloride, and combinations of aluminum nitrate, aluminum sulfate, and aluminum chloride.

[0025] Preferably, the yttrium salt includes any one or a combination of two of yttrium nitrate, yttrium sulfate, or yttrium chloride. Typical but non-limiting combinations include combinations of yttrium nitrate and yttrium sulfate, combinations of yttrium sulfate and yttrium chloride, combinations of yttrium nitrate and yttrium chloride, and combinations of yttrium nitrate, yttrium sulfate, and yttrium chloride.

[0026] Preferably, the polymer comprises any one or a combination of at least two of polyvinylpyrrolidone, polyethylene glycol, hydroxypropyl cellulose, or hydroxypropyl methylcellulose. Typical but non-limiting combinations include combinations of polyvinylpyrrolidone and polyethylene glycol, combinations of polyethylene glycol and hydroxypropyl cellulose, combinations of hydroxypropyl cellulose and hydroxypropyl methylcellulose, combinations of polyvinylpyrrolidone, hydroxypropyl cellulose, and hydroxypropyl methylcellulose, combinations of polyethylene glycol, hydroxypropyl cellulose, and hydroxypropyl methylcellulose, and combinations of polyvinylpyrrolidone, polyethylene glycol, hydroxypropyl cellulose, and hydroxypropyl methylcellulose, with polyvinylpyrrolidone being the most preferred.

[0027] Preferably, the amount of polymer added is 1 g / L-100 g / L based on the total volume of the metal ion salt solution. For example, it can be 1 g / L, 10 g / L, 20 g / L, 30 g / L, 40 g / L, 50 g / L, 60 g / L, 70 g / L, 80 g / L, 90 g / L, or 100 g / L, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0028] Preferably, the temperature of the heating reaction is 120℃-230℃, for example, it can be 120℃, 130℃, 140℃, 150℃, 160℃, 170℃, 180℃, 190℃, 200℃, 210℃, 220℃ or 230℃, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 140℃-190℃.

[0029] Preferably, the heating reaction time is 2h-30h, for example, it can be 2h, 6h, 10h, 15h, 20h, 25h or 30h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0030] Preferably, after the reaction, before obtaining submicron-sized cerium-doped yttrium aluminum garnet powder material, the process further includes solid-liquid separation, washing, and drying.

[0031] Preferably, the drying temperature is 80℃-110℃, for example, it can be 80℃, 85℃, 90℃, 95℃, 100℃, 105℃ or 110℃, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0032] Preferably, the drying time is 2h-30h, for example, it can be 2h, 6h, 10h, 15h, 20h, 25h or 30h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0033] Preferably, the calcination includes oxidative calcination and reducing calcination.

[0034] Preferably, the oxidative calcination atmosphere includes an air atmosphere.

[0035] Preferably, the reducing calcination atmosphere includes any one or at least a combination of two of the following: a hydrogen atmosphere, an ammonia atmosphere, or a carbon reducing atmosphere.

[0036] Preferably, the calcination temperature is 1000℃-1600℃, for example, it can be 1000℃, 1050℃, 1100℃, 1150℃, 1200℃, 1250℃, 1300℃, 1350℃, 1400℃, 1450℃, 1500℃, 1550℃ or 1600℃, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0037] Preferably, the calcination time is 0.5h-5h, for example, it can be 0.5h, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h or 5h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 2h-3h.

[0038] Preferably, during the calcination process, the heating rate is 5°C / min during the process of heating from room temperature to 600°C, the heating rate is 2°C / min during the process of heating from 600°C to the target calcination temperature, and the holding time at the calcination temperature is 0.5-5h, preferably 2h.

[0039] As a preferred embodiment of the preparation method of the present invention, the preparation method includes the following steps:

[0040] A metal ion salt solution with a concentration of 0.1 mol / L to 1.0 mol / L is obtained by mixing yttrium salt, aluminum salt, cerium salt, and ethylene glycol and water in a volume ratio of (0.1-2):1 according to a molar ratio of (3-2.5) mol: 5 mol: (0-0.5) mol.

[0041] A mixed metal ion salt solution and a polymer were heated and reacted at 120℃-230℃ for 2h-30h. After solid-liquid separation and washing, the mixture was dried at 80℃-110℃ for 2h-30h to obtain the precursor powder material.

[0042] The precursor powder material is first calcined in air at 1000℃-1600℃ for 2-3 hours, and then calcined in a reducing atmosphere at 1000℃-1600℃ for 2-3 hours to obtain the submicron-sized cerium-doped yttrium aluminum garnet powder material.

[0043] In a second aspect, the present invention provides a submicron-sized cerium-doped yttrium aluminum garnet powder material prepared by the preparation method described in the first aspect.

[0044] The general chemical formula of the submicron-sized cerium-doped yttrium aluminum garnet powder material is: Y 3-x Ce x Al5O 12 , where 0 < x < 0.5, for example, it can be 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45 or 0.5, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0045] The average particle size of the submicron-sized cerium-doped yttrium aluminum garnet powder material is 70nm-1000nm, for example, it can be 70nm, 100nm, 200nm, 300nm, 400nm, 500nm, 600nm, 700nm, 800nm, 900nm or 1000nm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0046] Thirdly, the present invention provides an application of the submicron-sized cerium-doped yttrium aluminum garnet powder material as described in the second aspect, wherein the submicron-sized cerium-doped yttrium aluminum garnet powder material is used in the field of white LED or transparent ceramic powder fluorescence luminescence.

[0047] The submicron-sized cerium-doped yttrium aluminum garnet powder material provided by this invention is used in the fields of fluorescence conversion and white light LEDs. The excitation spectrum peak is located at 458nm, which can be well matched with blue light chips. The emission spectrum peak is located at 542nm, and the internal quantum efficiency can reach 88.3%.

[0048] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0049] Compared with the prior art, the present invention has at least the following beneficial effects:

[0050] (1) This invention employs a hydrothermal alcohol solvothermal synthesis method, using a mixed solvent formed by mixing a single alcohol organic solvent with water. By controlling the nucleation and growth of yttrium aluminum garnet precursors, Ce can be prepared with high sphericity, uniform morphology, narrow particle size distribution, and a wide adjustable size range. 3+ The cerium-doped yttrium aluminum garnet powder precursor powder, after being calcined at high temperature, yields a cerium-doped yttrium aluminum garnet powder material with a near-spherical morphology, narrow particle size distribution, and uniform morphology in the submicron size.

[0051] (2) The size-tunable submicron cerium-doped yttrium aluminum garnet powder material provided by the present invention has a wide range of adjustable size from 70nm to 1000nm, and the powder most suitable for transparent ceramic sintering can be freely selected.

[0052] (3) The submicron-sized cerium-doped yttrium aluminum garnet powder material provided by the present invention is used in the fields of fluorescence conversion and white light LED. The excitation spectrum peak is located at 458nm, which can be well matched with blue light chips. The emission spectrum peak is located at 542nm, and the internal quantum efficiency can reach 88.3%. Attached Figure Description

[0053] Figure 1 This is a SEM image of the precursor powder material in Embodiment 1 of the present invention;

[0054] Figure 2 The Ce obtained in Embodiment 1 of the present invention 3+ XRD pattern of yttrium aluminum garnet powder material;

[0055] Figure 3 Ce obtained in Embodiment 1 of the present invention 3+ SEM image of yttrium aluminum garnet powder material;

[0056] Figure 4 Ce obtained in Embodiment 1 of the present invention 3+ Excitation and emission spectra of yttrium aluminum garnet powder materials;

[0057] Figure 5 Ce obtained in Example 4 of the present invention 3+ SEM image of yttrium aluminum garnet powder material;

[0058] Figure 6 Ce obtained in Example 5 of the present invention 3+ SEM image of yttrium aluminum garnet powder material;

[0059] Figure 7 Ce obtained in Example 6 of the present invention 3+ SEM image of yttrium aluminum garnet powder material;

[0060] Figure 8 Ce obtained in Example 7 of the present invention 3+ SEM image of yttrium aluminum garnet powder material;

[0061] Figure 9 Ce obtained in Example 8 of the present invention 3+ SEM image of yttrium aluminum garnet powder material;

[0062] Figure 10 Ce obtained in Example 9 of the present invention 3+ SEM image of yttrium aluminum garnet powder material;

[0063] Figure 11 Ce obtained in Embodiment 1 of the present invention 3+ Spectral distribution of yttrium aluminum garnet powder material in LED emission. Detailed Implementation

[0064] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments. However, the following examples are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims.

[0065] Unless otherwise specified, all reagents and consumables used in the following examples and comparative examples were purchased from conventional reagent manufacturers in the art; unless otherwise specified, the experimental methods and techniques used were conventional methods and techniques in the art.

[0066] Example 1

[0067] This embodiment provides a method for preparing submicron-sized cerium-doped yttrium aluminum garnet powder, the method comprising the following steps:

[0068] (1) Yttrium nitrate, aluminum nitrate, cerium nitrate, and ethylene glycol and water in a volume ratio of 1:1 were mixed in a molar ratio of 2.95:5:0.05 to obtain a metal ion salt solution with a concentration of 0.6 mol / L of yttrium nitrate; the metal ion salt solution was mixed with polyvinylpyrrolidone (K30) with a concentration of 1 wt%, and the reaction solution was transferred to a polytetrafluoroethylene reactor and heated at 180 °C for 15 h. After solid-liquid separation and washing, the mixture was dried at 80 °C for 12 h to obtain the precursor powder material.

[0069] (2) The precursor powder material was first calcined at 1350°C for 2 hours in an air atmosphere, and then naturally cooled to room temperature before being calcined at 1350°C for 2 hours in a hydrogen and nitrogen atmosphere to obtain Ce. 3+ Doped YAG powder material.

[0070] Figure 1 The image shows a scanning electron microscope (SEM) image of the precursor powder material. The results show that the powder is composed of approximately spherical particles, exhibits monodispersity, has a uniform particle size distribution, and an average size of 640 nm.

[0071] Figure 2 For Ce 3+X-ray diffraction (XRD) analysis of the doped YAG powder material showed that the prepared powder was a pure garnet phase. The diffraction patterns of the (321), (400), (420), and (422) crystal planes of the YAG powder were clearly visible in the XRD pattern, with sharp peaks, indicating that the prepared Ce... 3+ The doped YAG powder has good crystallinity.

[0072] Figure 3 For Ce 3+ Scanning electron microscope (SEM) images of the doped YAG powder show that the powder consists of approximately spherical particles with monodisperse characteristics, uniform particle size distribution, and an average size of 580 nm. After calcination, the size decreases to some extent.

[0073] Figure 4 For Ce 3+ The excitation and emission spectra of the doped YAG powder are shown in the image. The results show that the excitation peak of the phosphor is located at 458 nm, which can be well matched with the blue light chip. The emission peak is located at 542 nm, and its internal quantum efficiency can reach 88.3%.

[0074] Example 2

[0075] This embodiment provides a method for preparing submicron-sized cerium-doped yttrium aluminum garnet powder, the method comprising the following steps:

[0076] (1) Yttrium sulfate, aluminum sulfate, cerium sulfate and methanol and water with a volume ratio of 0.5:1 were mixed in a molar ratio of 2.99:5:0.01 to obtain a metal ion salt solution with a concentration of 0.5 mol / L; the mixed metal ion salt solution was then mixed with polyvinylpyrrolidone (K30) with a concentration of 5 wt%, and the reaction solution was transferred to a polytetrafluoroethylene reactor and heated at 140 °C for 16 h. After solid-liquid separation and washing, the mixture was dried at 100 °C for 10 h to obtain the precursor powder material.

[0077] (2) The precursor powder material was first calcined at 1000°C for 3 hours in an air atmosphere, and then naturally cooled to room temperature before being calcined at 1000°C for 3 hours in a hydrogen and nitrogen atmosphere to obtain Ce. 3+ Doped YAG powder material.

[0078] Example 3

[0079] This embodiment provides a method for preparing submicron-sized cerium-doped yttrium aluminum garnet powder, the method comprising the following steps:

[0080] (1) Yttrium nitrate, aluminum chloride, cerium chloride, and isopropanol and water in a volume ratio of 1.5:1 were mixed in a molar ratio of 2.75:5:0.25 to obtain a metal ion salt solution with a concentration of 0.8 mol / L of yttrium chloride; the metal ion salt solution was mixed with polyvinylpyrrolidone (K30) with a concentration of 20 wt%, and the reaction solution was transferred to a polytetrafluoroethylene reactor and heated at 190 °C for 15 h. After solid-liquid separation and washing, the mixture was dried at 90 °C for 12 h to obtain the precursor powder material.

[0081] (2) The precursor powder material was first calcined at 1500°C for 1.5 h in an air atmosphere, and then naturally cooled to room temperature before being calcined at 1500°C for 1.5 h in a hydrogen and nitrogen atmosphere to obtain Ce. 3+ Doped YAG powder material.

[0082] Example 4

[0083] This embodiment provides a method for preparing submicron-sized cerium-doped yttrium aluminum garnet powder material. The only difference from Embodiment 1 is that in step (1), yttrium nitrate, aluminum nitrate, cerium nitrate, and ethylene glycol and water with a volume ratio of 1:1 are mixed in a molar ratio of 2.95:5:0.05 to obtain a metal ion salt solution with a yttrium salt concentration of 0.1 mol / L.

[0084] Figure 5 The Ce prepared 3+ Scanning electron microscope (SEM) image of the doped YAG powder material. The image results show that the powder is composed of approximately spherical particles, exhibits monodispersity characteristics, has a uniform particle size distribution, and an average size of 80 nm.

[0085] Example 5

[0086] This embodiment provides a method for preparing submicron-sized cerium-doped yttrium aluminum garnet powder material. The only difference from Example 1 is that in step (1), yttrium nitrate, aluminum nitrate, cerium nitrate, and ethylene glycol and water with a volume ratio of 1:1 are mixed in a molar ratio of 2.95:5:0.05 to obtain a metal ion salt solution with a yttrium salt concentration of 0.3 mol / L.

[0087] Figure 6 The Ce prepared 3+ Scanning electron microscope (SEM) image of the doped YAG powder material. The image results show that the powder is composed of approximately spherical particles, exhibits monodispersity characteristics, has a uniform particle size distribution, and an average size of 190 nm.

[0088] Example 6

[0089] This embodiment provides a method for preparing submicron-sized cerium-doped yttrium aluminum garnet powder material. The only difference from Example 1 is that in step (1), yttrium nitrate, aluminum nitrate, cerium nitrate, and ethylene glycol and water with a volume ratio of 1:1 are mixed in a molar ratio of 2.95:5:0.05 to obtain a metal ion salt solution with a yttrium salt concentration of 0.45 mol / L.

[0090] Figure 7 The Ce prepared 3+ Scanning electron microscope (SEM) image of the doped YAG powder material. The image results show that the powder is composed of approximately spherical particles, exhibits monodispersity characteristics, has a uniform particle size distribution, and an average size of 270 nm.

[0091] Example 7

[0092] This embodiment provides a method for preparing submicron-sized cerium-doped yttrium aluminum garnet powder material. The only difference from Example 1 is that in step (1), yttrium nitrate, aluminum nitrate, cerium nitrate, and ethylene glycol and water with a volume ratio of 1:1 are mixed in a molar ratio of 2.95:5:0.05 to obtain a metal ion salt solution with a yttrium salt concentration of 1.2 mol / L.

[0093] Figure 8 The Ce prepared 3+ Scanning electron microscope (SEM) image of the doped YAG powder material. The image results show that the powder is composed of approximately spherical particles, exhibits monodispersity characteristics, has a uniform particle size distribution, and an average size of 1260 nm.

[0094] Example 8

[0095] This embodiment provides a method for preparing submicron-sized cerium-doped yttrium aluminum garnet powder material. The only difference from Example 1 is that the ethylene glycol in step (1) is replaced with an equal volume of ethanol.

[0096] Figure 9 The Ce prepared 3+ Scanning electron microscope (SEM) image of the doped YAG powder material. The image results show that the powder is composed of approximately spherical particles, exhibits monodispersity characteristics, has a uniform particle size distribution, and an average size of 540 nm.

[0097] This embodiment illustrates that ethanol has a similar effect to ethylene glycol, and ethanol can replace ethylene glycol.

[0098] Example 9

[0099] This embodiment provides a method for preparing submicron-sized cerium-doped yttrium aluminum garnet powder material. The only difference from Example 1 is that the heating temperature in step (1) is 200°C.

[0100] Figure 10 The Ce prepared 3+ Scanning electron microscope (SEM) images of the doped YAG powder material show that the powder consists of approximately spherical particles with a certain degree of widening of the particle size distribution, and some particles are agglomerated with an average size of 600 nm.

[0101] This embodiment illustrates that higher hydrothermal solvothermal conditions can also prepare better Ce. 3+ Doped YAG powder, but the higher reaction temperature consumes more energy.

[0102] Example 10

[0103] This embodiment provides a method for preparing submicron-sized cerium-doped yttrium aluminum garnet powder material. The only difference from Embodiment 1 is that the calcination temperature in step (2) is 900°C.

[0104] The Ce prepared in this embodiment 3+ The doped YAG powder material consists of approximately spherical particles, exhibiting monodispersity and uniform particle size distribution with an average size of 580 nm. However, the luminescence intensity of the sample is lower than that of Example 1, being only 65.4% of that of Example 1.

[0105] Example 11

[0106] This embodiment provides a method for preparing submicron-sized cerium-doped yttrium aluminum garnet powder material. The only difference from Example 1 is that the heating temperature in step (1) is 240°C.

[0107] The Ce prepared in this embodiment 3+ The doped YAG powder material is composed of approximately spherical particles with extremely uneven particle size distribution, ranging from 100 nm to 1.5 μm. This indicates that under excessively high temperature conditions, the reaction will cause continuous nucleation and growth, making it impossible to obtain products with uniform size.

[0108] Comparative Example 1

[0109] This comparative example provides a method for preparing cerium-doped yttrium aluminum garnet powder material. The only difference from Example 1 is that polyvinylpyrrolidone (K30) polymer was not added in step (1), while the other steps remained unchanged.

[0110] Ce prepared in this comparative example 3+ The doped YAG powder consists of spherical particles, small particles, and agglomerated solids. The size of the spherical particles ranges from hundreds of nanometers to several micrometers, while the agglomerated solids are particles larger than micrometers.

[0111] Comparative Example 2

[0112] This comparative example provides a method for preparing cerium-doped yttrium aluminum garnet powder material. The only difference from Example 1 is that in step (1), ethylene glycol is replaced with an equal volume of water, while the other steps remain unchanged. After the reaction is completed, no precipitate is produced in the reaction solution, indicating that without the addition of alcohol, the precipitation reaction cannot proceed.

[0113] Application Example 1

[0114] The Ce obtained in Example 1 above 3+ Doped YAG powder was used to encapsulate a white LED with a blue LED chip, and the optical performance of the LED was tested.

[0115] Ce 3+ Doped YAG powder and epoxy resin were mixed uniformly at a mass ratio of 1:4. This mixture was then coated onto a blue LED chip with a main emission peak at 450 nm, encapsulated, and cured at 150°C for 2 hours to obtain a white LED light source with a color rendering index of 87.1. The spectrum of the obtained LED light source was tested using an LED spectrometer, and its spectral distribution is shown below. Figure 11 As shown, the spectrum exhibits good continuity.

[0116] In addition, Ce 3+ Doped YAG powder, (Ca,Sr)AlSiN3:Eu 2+ A mixture of epoxy resin and a white LED light source with a color rendering index of 87.1 was obtained by uniformly mixing the two components at a mass ratio of 2:1:8. This mixture was then coated onto a blue LED chip with a main emission peak at 450nm, encapsulated, and cured at 150℃ for 2 hours. The spectrum of the obtained LED light source was tested using an LED spectrometer, and its spectral distribution is shown below. Figure 11 As shown, the spectrum exhibits good continuity.

[0117] Ce prepared in the embodiments and comparative examples of the present invention 3+ The particle size distribution of the doped YAG powder material is shown in Table 1 below:

[0118] Table 1

[0119]

[0120]

[0121] The test results show that:

[0122] (1) As can be seen from Examples 1-8, the present invention uses a hydrothermal alcohol solvothermal synthesis method, using a mixed solvent formed by mixing a single alcohol organic solvent with water, and controls the nucleation and growth of yttrium aluminum garnet precursors. After high-temperature calcination, cerium-doped yttrium aluminum garnet powder material with a near-spherical morphology, narrow particle size distribution, and uniform morphology with a submicron size can be obtained. Its size can be adjusted in a wide range from 70nm to 1000nm, and the powder most suitable for sintering transparent ceramics can be freely selected.

[0123] (2) A comparison between Example 1 and Example 9 shows that when the heating temperature in step (1) is 200°C, higher hydrothermal solvothermal conditions can also prepare better Ce. 3+ Doped YAG powder, but the higher reaction temperature consumes more energy; a comparison between Example 1 and Example 11 shows that when the heating temperature in step (1) is too high, at 240°C, Ce 3+ Doped YAG powder materials are composed of nearly spherical particles with extremely uneven particle size distribution. The particle size ranges from 100nm to 1.5μm, making it impossible to obtain products with uniform size.

[0124] (3) A comparison between Example 1 and Example 10 shows that when the calcination temperature is too low, Ce will... 3+ The luminescence intensity of doped YAG powder materials decreases.

[0125] (4) As can be seen from Example 1, Comparative Example 1 and Comparative Example 2, the present invention uses a mixed solvent formed by mixing alcohol organic solvent and water, and controls the reaction rate by adjusting the alcohol substance and reaction temperature, so as to control the nucleation and growth of yttrium aluminum garnet precursor, and realizes the controllable synthesis of precursor particles by utilizing the slow growth of nanocrystals.

[0126] In summary, this invention employs a hydrothermal solvothermal synthesis method, using a mixed solvent formed by mixing a single alcohol organic solvent with water. By controlling the nucleation and growth of yttrium aluminum garnet precursors and calcining at high temperatures, cerium-doped yttrium aluminum garnet powder materials with near-spherical morphology, narrow particle size distribution, and uniform morphology in submicron sizes are obtained. The size of these powders is adjustable over a wide range from 70 nm to 1000 nm, allowing for the free selection of the powder most suitable for use in transparent ceramic sintering.

[0127] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing submicron-sized cerium-doped yttrium aluminum garnet powder material, characterized in that, The preparation method includes the following steps: A solution of metal ion salts is obtained by mixing yttrium salts, aluminum salts, cerium salts, and solvents; A mixed metal ion salt solution and a polymer were heated and reacted at 120℃-230℃ for 2h-30h. After solid-liquid separation and washing, the mixture was dried at 80℃-110℃ for 2h-30h to obtain the precursor powder material. The precursor powder material is first calcined in air at 1000℃-1600℃ for 2h-3h, and then calcined in a reducing atmosphere at 1000℃-1600℃ for 2h-3h to obtain the submicron-sized cerium-doped yttrium aluminum garnet powder material. The polymer is polyvinylpyrrolidone, and the solvent includes alcoholic organic solvents and water.

2. The preparation method according to claim 1, characterized in that, The volume ratio of alcoholic organic solvent to water in the solvent is (0.1-2):

1.

3. The preparation method according to claim 1, characterized in that, The alcoholic organic solvents include any one or a combination of at least two of methanol, ethanol, ethylene glycol, isopropanol, butanol, diethylene glycol, or glycerol.

4. The preparation method according to claim 3, characterized in that, The alcoholic organic solvent is methanol, ethanol, or ethylene glycol.

5. The preparation method according to claim 1, characterized in that, The concentration of yttrium salt in the metal ion salt solution is 0.1 mol / L to 1.0 mol / L.

6. The preparation method according to claim 1, characterized in that, The molar ratio of yttrium salt, aluminum salt, and cerium salt in the metal ion salt solution is (3-2.5) mol: 5 mol: (0-0.5) mol.

7. The preparation method according to claim 1, characterized in that, The cerium salt includes any one or a combination of at least two of cerium nitrate, cerium ammonium nitrate, cerium sulfate, or cerium chloride.

8. The preparation method according to claim 1, characterized in that, The aluminum salt includes any one or a combination of at least two of aluminum nitrate, aluminum sulfate, or aluminum chloride.

9. The preparation method according to claim 1, characterized in that, The yttrium salt includes any one or a combination of two of yttrium nitrate, yttrium sulfate, or yttrium chloride.

10. The preparation method according to claim 1, characterized in that, The amount of polymer added is 1 g / L to 100 g / L, based on the total volume of the metal ion salt solution.

11. The preparation method according to claim 1, characterized in that, The temperature of the heating reaction is 140℃-190℃.

12. The preparation method according to claim 1, characterized in that, The reducing atmosphere includes any one or at least a combination of two of the following: a hydrogen atmosphere, an ammonia atmosphere, or a carbon reducing atmosphere.

13. A submicron-sized cerium-doped yttrium aluminum garnet powder material, characterized in that, The submicron-sized cerium-doped yttrium aluminum garnet powder material is prepared by the preparation method according to any one of claims 1-12; the general chemical formula of the submicron-sized cerium-doped yttrium aluminum garnet powder material is: Y 3-x Ce x Al5O 12 , where 0 < x < 0.5; The average particle size of the submicron-sized cerium-doped yttrium aluminum garnet powder material is 70 nm-1000 nm.

14. An application of the submicron-sized cerium-doped yttrium aluminum garnet powder material as described in claim 13, characterized in that, The submicron-sized cerium-doped yttrium aluminum garnet powder material is used in the fields of white LEDs or transparent ceramic powder fluorescence luminescence.

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