Single-matrix triple-doped white fluorescent material and preparation method thereof

Abstract

The invention relates to the technical field of optoelectronic materials, in particular to a single-matrix triple-doped white fluorescent material and a preparation method thereof, the chemical composition expression of the single-matrix triple-doped white fluorescent material is M1-x-y-zAl2O4: xCe < 3 + >, yTb < 3 + > and zMn < 2 + >, three ions of Mn < 2 + >, Ce < 3 + > and Tb < 3 + > are jointly doped into an MAl2O4 (M = Mg, Ca, Sr and Ba) aluminate matrix, the doping concentrations of Ce < 3 + >, Tb < 3 + > and Mn < 2 + > are accurately regulated and controlled (0.005-0.03, 0.02-0.1 and 0.01-0.1 respectively), and the single-matrix triple-doped white fluorescent material is obtained. According to the method, Mn < 2 + > occupies specific sites in a matrix crystal structure, the peak value of an emission spectrum of the Mn < 2 + > is accurately regulated and controlled at a red light wave band of 620-700nm, and meanwhile, a three-doped system capable of realizing efficient energy cascade transfer in a single matrix is successfully constructed by virtue of efficient absorption of Ce < 3 + > on 350-420nm near ultraviolet light, energy transfer from Ce < 3 + > to Tb < 3 + > and final energy transfer from Tb < 3 + > to Mn < 2 + >. Therefore, the fundamental technical obstacle that in the prior art, it is difficult to achieve efficient synergistic luminescence in a single matrix through multi-ion combination is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optoelectronic materials, and particularly relates to a single-matrix three-doped white fluorescent material and a preparation method thereof. BACKGROUND

[0002] As a new generation of illumination light source, white light emitting diode (LED) has been widely used, and its mainstream technical scheme relies on the combination of LED chip and fluorescent powder. In the current commercial scheme, the combination of blue chip and YAG:Ce3+ yellow fluorescent powder usually has a low color rendering index due to the lack of red light component; and the combination of ultraviolet chip and multi-color fluorescent powder has problems such as spectral reabsorption and inconsistent aging, resulting in light efficiency decline and color drift. Therefore, single-matrix white fluorescent powder has become a research hotspot because it can avoid the defects of multi-phase mixing.

[0003] The existing single-matrix white fluorescent powder system still faces challenges such as insufficient red light component, difficulty in continuous adjustment of color temperature, poor thermal stability, and high cost of rare earth raw materials. As a fluorescent powder matrix, aluminate system (MAl2O4) has the advantages of good stability and mature process, and is an ideal choice. Meanwhile, transition metal ion Mn2+ can be used as a low-cost and tunable red component because its luminescent color (from green to red) is strongly dependent on the crystal field strength.

[0004] However, in the existing single-matrix white fluorescent powder, how to effectively combine Mn2+ ions with the aluminate matrix and rare earth ions Ce3+ and Tb3+ to form a single-matrix three-doped system with high-efficiency luminescence still faces fundamental technical obstacles. SUMMARY

[0005] The present application aims to provide a single-matrix three-doped white fluorescent material and a preparation method thereof, which solves the problem that in the existing single-matrix white fluorescent powder, how to effectively combine Mn2+ ions with the aluminate matrix and rare earth ions Ce3+ and Tb3+ to form a single-matrix three-doped system with high-efficiency luminescence still faces fundamental technical obstacles.

[0006] To achieve the above-mentioned purpose, the present application provides a single-matrix three-doped white fluorescent material, and the chemical composition expression of the single-matrix three-doped white fluorescent material is M1-x-y-zAl2O4:xCe3+,yTb3+,zMn2+. In the formula, x, y, and z are respectively the molar percentage content of doped ions Ce3+, Tb3+, and Mn2+ relative to the substitution of alkali earth metal ions M2+. Wherein: M is at least one element selected from Mg, Ca, Sr, and Ba; The value ranges of x, y, and z are respectively 0.005≤x≤0.03, 0.02≤y≤0.1, and 0.01≤z≤0.1. The emission spectrum peak wavelength of the Mn2+ ion in the single-matrix three-doped white fluorescent material is in the range of 620 nm to 700 nm.

[0007] The single-matrix three-doped white fluorescent material has a MAl2O4 main crystal phase of an orthorhombic system or a tetragonal system, wherein the Mn2+ ion occupies an octahedral site, and the crystal field strength parameter 10Dq value of the octahedral site is in the range of 7500 cm-1 to 8500 cm-1.

[0008] The average particle size D50 of the single-matrix three-doped white fluorescent material is 5-30 μm, the particle size distribution satisfies (D90-D10) / D50≤2.0, and the tap density is 1.8-3.2 g / cm3.

[0009] The surface of the single-matrix three-doped white fluorescent material is coated with a composite protective layer, and the composite protective layer comprises, from inside to outside, an inorganic oxide layer with a thickness of 5-40 nm and an organic modification layer with a thickness of 1-8 nm.

[0010] The application further provides a preparation method of the single-matrix three-doped white fluorescent material. The precursor preparation step comprises the following steps: according to the stoichiometric ratio of the chemical formula M1-x-y-zAl2O4:xCe3+,yTb3+,zMn2+, M source compounds, aluminum sources, cerium sources, terbium sources and manganese sources are weighed, and are blended in an aqueous solution in the presence of an organic complexing agent to obtain a precursor mixture. The precursor treatment step comprises the following steps: the obtained precursor mixture is dried and pre-fired at a pre-firing temperature of 600-900 ℃ for a pre-firing time of 2-6 hours to obtain a pre-fired intermediate. The step of segmented high-temperature sintering comprises the following steps: the obtained pre-fired intermediate is sequentially subjected to a first-stage temperature rising sintering, a second-stage high-temperature pulse treatment and a third-stage temperature reduction treatment under the protection of a reducing atmosphere to obtain a sintered product. The post-treatment and classification step comprises the following steps: the sintered product is crushed and ground, and the fluorescent powder with a target particle size is obtained through classification. The surface coating step comprises the following steps: at least one of atomic layer deposition, sol-gel method or chemical precipitation method is used to form a composite protective layer on the surface of the fluorescent powder.

[0011] In the precursor preparation step, the organic complexing agent is at least one of citric acid, tartaric acid, ethylenediaminetetraacetic acid or gluconic acid, and the amount of the organic complexing agent is 1-3 times the total molar amount of metal ions.

[0012] The specific content of the step of segmented high-temperature sintering is as follows: First stage: the pre-sintered intermediate is heated to 1250-1400℃ in a N2 / H2 mixed atmosphere containing 3-8% H2, and is kept at the temperature for 2-5 hours; Second stage: the atmosphere is switched to a N2 / H2 mixed atmosphere containing 10-20% H2, and the heating is continued to 1400-1600℃, and a pulse heat treatment is performed at the temperature, which includes at least 2 temperature fluctuations within the range of ±30℃ of the target temperature, and each fluctuation lasts for 10-60 minutes; Third stage: the sintered product is obtained by programming the temperature to 700-1000℃ at a rate of 0.5-3℃ / min under the protection of a reducing atmosphere, and then cooling to room temperature with the furnace.

[0013] In the precursor preparation step, the M source compound is an oxalate or an alkali carbonate of M; The aluminum source is boehmite, pseudo-boehmite, aluminum isopropoxide or aluminum nitrate; The cerium source is cerous nitrate, cerous acetate or cerous oxalate; The terbium source is terbium nitrate, terbium acetate or terbium chloride; The manganese source is manganese acetate, manganese nitrate or manganese sulfate.

[0014] The single-matrix three-doped white fluorescent material and the preparation method thereof, the chemical composition expression of the single-matrix three-doped white fluorescent material is: M1-x-y-zAl2O4: xCe3+, yTb3+, zMn2+, by doping Mn2+, Ce3+ and Tb3+ ions into MAl2O4 (M=Mg, Ca, Sr, Ba) aluminate matrix, and accurately controlling the doping concentration of Ce3+, Tb3+ and Mn2+ (0.005-0.03, 0.02-0.1 and 0.01-0.1 respectively), the Mn2+ occupies a specific lattice site in the crystal structure of the matrix, and the emission spectrum peak is accurately controlled in the red light band of 620-700nm, and by means of the high-efficiency absorption of Ce3+ to 350-420nm near-ultraviolet light, the energy transfer from Ce3+ to Tb3+, and the final energy transfer from Tb3+ to Mn2+, a three-doped system capable of realizing efficient energy cascade transfer in a single matrix is successfully constructed, thereby solving the fundamental technical obstacle that the combination of multiple ions in the prior art is difficult to realize efficient synergistic luminescence in a single matrix. BRIEF DESCRIPTION OF DRAWINGS

[0015] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description only constitute some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained from these drawings without creative labor.

[0016] Fig. 1 is a step flow chart of the preparation method of the single-matrix three-doped white fluorescent material provided by the present application.

[0017] Fig. 2 is a specific step flow chart of the segmented high-temperature sintering step provided by the present application.

[0018] Fig. 3 is a specific step flow chart of the surface coating step provided by the present application. DETAILED DESCRIPTION

[0019] The embodiments of the present application will be described in detail below, and examples of the embodiments are shown in the drawings, wherein the same or similar reference signs represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are intended to explain the present application, and cannot be understood as a limitation of the present application.

[0020] The present application provides a single-matrix three-doped white fluorescent material, and a chemical composition expression of the single-matrix three-doped white fluorescent material and a preparation method thereof is as follows: M1-x-y-zAl2O4:xCe3+,yTb3+,zMn2+. In the formula, x, y, and z are respectively the molar percentage content of the doping ions Ce3+, Tb3+, and Mn2+ relative to the substituted alkali earth metal ions M2+. Wherein: M is at least one element selected from Mg, Ca, Sr, and Ba; The value ranges of x, y, and z are respectively: 0.005≤x≤0.03, 0.02≤y≤0.1, and 0.01≤z≤0.1. The emission spectrum peak wavelength of the Mn2+ ions in the single-matrix three-doped white fluorescent material is located in the range of 620nm to 700nm.

[0021] In the embodiment, by co-doping Mn2+, Ce3+, and Tb3+ ions into a MAl2O4 (M=Mg, Ca, Sr, Ba) aluminate matrix and precisely controlling the doping concentrations of Ce3+, Tb3+, and Mn2+ (0.005-0.03, 0.02-0.1, and 0.01-0.1, respectively), the Mn2+ ions are allowed to occupy specific lattice sites in the crystal structure of the matrix, and the emission spectrum peak of the Mn2+ ions is precisely controlled in the red light band of 620-700 nm. Meanwhile, by means of the high-efficiency absorption of near-ultraviolet light of 350-420 nm by Ce3+, the energy transfer from Ce3+ to Tb3+, and the final energy transfer from Tb3+ to Mn2+, a three-doped system capable of realizing high-efficiency energy cascade transfer in a single matrix is successfully constructed, thereby solving the fundamental technical obstacle that the combination of multiple ions in the prior art is difficult to realize high-efficiency synergistic luminescence in a single matrix.

[0022] Further, the single-matrix three-doped white fluorescent material has a MAl2O4 main crystal phase of an orthorhombic system or a tetragonal system, wherein the Mn2+ ions occupy octahedral lattice sites, and the crystal field strength parameter 10Dq value of the octahedral lattice sites is in the range of 7500 cm-1 to 8500 cm-1.

[0023] In the embodiment, by selecting MAl2O4 of an orthorhombic or tetragonal system as the matrix, the introduced Mn2+ ions are allowed to stably occupy the octahedral lattice sites in the crystal structure thereof, and the crystal field strength (10Dq) of the lattice sites is precisely controlled in the specific range of 7500 cm-1 to 8500 cm-1. First, the Mn2+ ions are ensured to produce high-efficiency red light emission at 620-700 nm, filling the red component in the spectrum. Second, the suitable crystal field environment and the specific crystal phase structure together create necessary conditions for high-efficiency and directional energy transfer from Ce3+ to Tb3+ to Mn2+, thereby fundamentally solving the technical obstacle that multiple ions are difficult to synergistically realize high-efficiency white light emission in a single matrix.

[0024] Further, the single-matrix three-doped white fluorescent material has an average particle size D50 of 5-30 μm, a particle size distribution satisfying (D90-D10) / D50≤2.0, and a tap density of 1.8-3.2 g / cm3.

[0025] In the embodiment, the above-mentioned physical property indexes ensure that the fluorescent powder particles have good dispersibility, packing density, and surface properties, which not only directly improves the coating uniformity and light extraction efficiency of the fluorescent powder in applications, but also provides an ideal substrate for subsequent implementation of a high-efficiency, dense, and uniform surface coating protection layer.

[0026] Further, the single-matrix three-doped white fluorescent material is coated with a composite protective layer, which comprises, from inside to outside, an inorganic oxide layer with a thickness of 5-40 nm and an organic modification layer with a thickness of 1-8 nm.

[0027] In the present embodiment, the inorganic oxide layer of the inner layer mainly provides a dense physical barrier to effectively block environmental factors such as moisture and oxygen from eroding and quenching the lattice and luminescent center of the fluorescent powder; the organic modification layer of the outer layer further enhances the environmental stability of the powder through its hydrophobic groups and special functional groups, and significantly improves the interfacial compatibility and dispersibility of the fluorescent powder and downstream application materials such as encapsulating resin.

[0028] Please refer to Figs. 1 to 3 The present application also provides a preparation method of a single-matrix three-doped white fluorescent material, which is used for preparing the single-matrix three-doped white fluorescent material as described above, and comprises the following steps: S1, precursor preparation: according to the stoichiometric ratio of the chemical formula M1-x-y-zAl2O4:xCe3+, yTb3+, zMn2+, M source compounds, aluminum source, cerium source, terbium source and manganese source are weighed, and are blended in an aqueous solution in the presence of an organic complexing agent to obtain a precursor mixture; S2, precursor treatment: the obtained precursor mixture is dried and pre-fired at a pre-firing temperature of 600-900℃ for 2-6 hours to obtain a pre-fired intermediate; S3, segmented high-temperature sintering: the obtained pre-fired intermediate is sequentially subjected to first-stage temperature rising sintering, second-stage high-temperature pulse treatment and third-stage temperature lowering treatment under the protection of a reducing atmosphere to obtain a sintered product; S4, post-treatment and classification: the sintered product is crushed, ground and classified to obtain a fluorescent powder with a target particle size; S5, surface coating: at least one of atomic layer deposition, sol-gel method or chemical precipitation method is used to form a composite protective layer on the surface of the fluorescent powder.

[0029] In the embodiment, by introducing an organic complexing agent and mixing in an aqueous phase, a highly uniform dispersion on the ion scale is achieved, laying a foundation for subsequent formation of a uniform crystal phase; in the segmented high-temperature sintering step, by a segmented high-temperature pulse sintering process, under a precisely controlled reducing atmosphere, not only is it ensured that Ce3+, Tb3+, and Mn2+ enter the lattice at target valence states and specific lattice sites, but also lattice defects are effectively eliminated and crystal perfect growth is promoted, thereby precisely regulating the crystal field environment (10Dq value) in which Mn2+ is located, and finally high-efficiency red light emission and energy transfer are obtained; the post-processing and grading steps precisely control the particle size, distribution, and tap density of the sintered product by crushing, grinding, and grading, and optimize the application performance thereof; and the surface coating step constructs a dense inorganic / organic composite protective layer on the surface of the powder by a selective surface coating technology, thereby fundamentally improving the long-term environmental stability and reliability of the material.

[0030] Further, in the precursor preparation step, the organic complexing agent is at least one of citric acid, tartaric acid, ethylenediaminetetraacetic acid, or gluconic acid, and the amount of the organic complexing agent is 1-3 times the total molar amount of metal ions.

[0031] In the embodiment, by selecting at least one of citric acid, tartaric acid, ethylenediaminetetraacetic acid (EDTA), or gluconic acid and controlling the amount thereof to be 1-3 times the total molar amount of metal ions, efficient and uniform complexing of alkaline earth metal ions (M2+) and doped ions (Ce3+, Tb3+, Mn2+) is achieved at the molecular level. Different metal ions are effectively prevented from being separated and aggregated due to differences in hydrolysis or precipitation rates in the subsequent solution evaporation and pre-sintering processes, and it is ensured that all components are highly uniformly mixed at the atomic scale. This uniformity is a fundamental prerequisite for subsequent obtaining a single and pure MAl2O4 main crystal phase and accurately and controllably entering three luminescent ions (Ce3+, Tb3+, Mn2+) into predetermined lattice sites.

[0032] Further, the specific content of the segmented high-temperature sintering step is as follows: S101, first stage: in a N2 / H2 mixed atmosphere containing 3-8% H2, the pre-sintered intermediate is heated to 1250-1400°C and held for 2-5 hours; S102, second stage: the atmosphere is switched to a N2 / H2 mixed atmosphere containing 10-20% H2, and heating is continued to 1400-1600°C, and pulse-type heat treatment is performed at this temperature, the pulse-type heat treatment including at least 2 temperature fluctuations within ±30°C of the target temperature, each fluctuation lasting for 10-60 minutes; S103, the third stage: under the protection of reducing atmosphere, the temperature is programmed to decrease to 700-1000℃ at a rate of 0.5-3℃ / min, and then the furnace is cooled to room temperature, to obtain the sintered product.

[0033] In the present embodiment, the first stage is performed under a moderate reducing atmosphere (3-8% H2) and at a relatively low temperature for a long time, aiming to gently and thoroughly decompose the organic residues and inorganic anions in the precursor, and to preliminarily form the skeleton of the target MAl2O4 crystal phase, while ensuring that Ce3+ and Tb3+ are reduced and preliminarily enter the crystal lattice. The second stage is performed by increasing the hydrogen concentration (10-20% H2) to create a stronger reducing environment, to ensure sufficient reduction and stable doping of Mn2+; more importantly, a pulse heat treatment is introduced at a high temperature of 1400-1600℃, by at least two temperature fluctuations within a range of ±30℃, to efficiently promote the migration and annihilation of defects in the crystal lattice, and to optimize the ion arrangement, by using the periodic changes of thermal stress and atomic diffusion, to form a specific crystal field strength (10Dq value of 7500-8500 cm-1) required for the octahedral site where the Mn2+ ions are located, so as to precisely control the red light emission wavelength thereof. The third stage adopts a slow programmed temperature decrease, to effectively release the internal stress accumulated in the high temperature stage, to lock the perfect crystal structure and luminescence center state, and to prevent the introduction of new defects by quenching.

[0034] Further, in the precursor preparation step, the M source compound is an oxalate or basic carbonate of M; The aluminum source is boehmite, pseudo-boehmite, aluminum isopropoxide or aluminum nitrate; The cerium source is cerous nitrate, cerous acetate or cerous oxalate; The terbium source is terbium nitrate, terbium acetate or terbium chloride; The manganese source is manganese acetate, manganese nitrate or manganese sulfate.

[0035] In the present embodiment, the oxalate or basic carbonate is selected as the M source because it can stably release basic oxides during thermal decomposition, and produce gas byproducts (such as CO, CO2) which are helpful for forming a loose precursor, facilitating subsequent uniform sintering. High-activity aluminum sources such as boehmite and pseudo-boehmite are selected to ensure that the aluminum component has good reactivity and dispersibility during complexation, which is conducive to the formation of a uniform aluminum-oxygen network. For the doping ions, soluble cerium sources such as cerous nitrate and cerous acetate, soluble terbium sources such as terbium nitrate and terbium acetate, and soluble manganese sources such as manganese acetate and manganese nitrate, have excellent complexing ability and compatibility with the selected organic complexing agent (such as citric acid, EDTA) in an aqueous solution system, and can achieve true homogeneous blending with the M source and aluminum source at the molecular / ion level, avoiding component segregation caused by differences in solubility or reactivity of the raw materials.

[0036] Further, the specific content of the surface coating step is: S201: using atomic layer deposition method, at 200-300℃, with trimethylaluminum and water as precursors, depositing Al2O3 layer with thickness of 5-30nm on the surface of the fluorescent powder; S202: immersing the obtained Al2O3 coated fluorescent powder into alcohol solution of tetraethyl orthosilicate, hydrolyzing and condensing under acidic condition to form SiO2 layer with thickness of 2-15nm; S203: immersing the obtained SiO2 coated fluorescent powder into solution containing silane coupling agent for surface modification treatment, and then drying at 50-120℃ to form organic modification layer on the outermost layer of the powder.

[0037] In the present embodiment, the ALD technology is used to deposit a uniform, dense and non-porous Al2O3 layer (5-30nm) on the surface of the powder, which serves as the first physical barrier to effectively block the penetration of water molecules and corrosive ions, and protect the internal luminescent center. A thin SiO2 layer (2-15nm) is further coated on the Al2O3 layer by sol-gel method. This SiO2 layer not only fills the possible micro defects of the Al2O3 layer, but also provides key chemical active sites with its abundant surface hydroxyl groups. The silane coupling agent reacts with the hydroxyl groups on the surface of the SiO2 layer to form an ultrathin organic molecular layer (1-8nm) through covalent bonding. This organic modification layer, on one hand, its hydrophobic groups arrange outward, greatly enhancing the hydrophobicity of the powder and chemically resisting water erosion; on the other hand, its functional groups (such as vinyl and epoxy groups) can significantly improve the interfacial compatibility and bonding force between the fluorescent powder and the organic encapsulating material (such as silica gel and epoxy resin).

[0038] The above only discloses one preferred embodiment of the present application, and of course cannot limit the scope of the present application. Those skilled in the art can understand that the above-mentioned embodiment can be implemented in whole or in part, and equivalent changes made according to the claims of the present application still fall within the scope of the present application.

Claims

1. A single-matrix three-doped white fluorescent material, characterized in that, The chemical composition expression of the single-matrix three-doped white fluorescent material is: M 1-x-y-z Al2O4: xCe 3+ ,yTb 3+ ,zMn 2 + ; In the formula, x, y, z are respectively doping ions Ce 3+ , Tb 3+ , Mn 2+ , and M 2+ is a mole percentage content of the relative substituted alkali earth metal ion. M is at least one element selected from Mg, Ca, Sr and Ba; x, y and z are in the range of 0.005≤x≤0.03, 0.02≤y≤0.1 and 0.01≤z≤0.1, respectively. Mn in the single host three-doped white fluorescent material 2+ The emission spectrum peak wavelength of the ion is in the range of 620 nm to 700 nm. 2.The single-matrix three-doped white fluorescent material according to claim 1, characterized in that, The single host three-doped white fluorescent material has a MAl204 host crystal phase of orthorhombic or tetragonal system, wherein M represents at least one of Mg, Ca, Sr, Ba, Zn, Mn, Co, Ni, Cu, Fe, Cr, Ti, V, Ga, Ge, In, Sn, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Bi 2+ The ion occupies an octahedral site, and the crystal field strength parameter 10Dq value of the octahedral site is in the range of 7500 cm -1 to 8500 cm -1 . 3.The single-matrix three-doped white fluorescent material according to claim 2, characterized in that, The average particle size D of the single-matrix three-doped white fluorescent material is 5-30 μm 50 The particle size distribution satisfies (D 90 -D 10 ) / D 50 ≤2.0, and the tap density is 1.8-3.2 g / cm 3 . 4.The single-matrix three-doped white fluorescent material according to claim 3, characterized in that, a composite protective layer is coated on the surface of the single-matrix three-doped white fluorescent material, and the composite protective layer comprises, from inside to outside, an inorganic oxide layer with a thickness of 5-40 nm and an organic modification layer with a thickness of 1-8 nm.

5. A method for producing a single host three-doped white fluorescent material, for producing the single host three-doped white fluorescent material according to claim 4, characterized by, comprising the following steps: The precursor is prepared according to the general chemical formula M 1-x-y-z Al2O4: xCe 3+ yTb 3+ zMn 2+ The stoichiometric ratio of M source compound, aluminum source, cerium source, terbium source and manganese source is weighed, and the blending is carried out in the aqueous solution in the presence of the organic complexing agent to obtain the precursor mixture. precursor treatment: drying and pre-sintering the obtained precursor mixture, the pre-sintering temperature is 600-900℃, and the pre-sintering time is 2-6 hours, to obtain a pre-sintered intermediate; staged high-temperature sintering: under the protection of a reducing atmosphere, the obtained pre-sintered intermediate is sequentially subjected to first-stage temperature rising sintering, second-stage high-temperature pulse treatment and third-stage temperature reduction treatment to obtain a sintered product; post-treatment and grading: crushing and grinding the sintered product, and obtaining a fluorescent powder with a target particle size through grading; surface coating: at least one of atomic layer deposition, sol-gel method or chemical precipitation method is used to form a composite protective layer on the surface of the fluorescent powder. 6.The preparation method of the single-matrix three-doped white fluorescent material according to claim 5, characterized in that, in the precursor preparation step, the organic complexing agent is at least one of citric acid, tartaric acid, ethylenediaminetetraacetic acid or gluconic acid, and the amount of the organic complexing agent is 1-3 times the total molar amount of metal ions. 7.The preparation method of the single-matrix three-doped white fluorescent material according to claim 6, characterized in that, the specific content of the staged high-temperature sintering step is as follows: first stage: under a N2 / H2 mixed atmosphere containing 3-8% H2, the pre-sintered intermediate is heated to 1250-1400℃ and kept for 2-5 hours; second stage: the atmosphere is switched to a N2 / H2 mixed atmosphere containing 10-20% H2, and the temperature is continuously raised to 1400-1600℃, and pulse-type heat treatment is performed at this temperature, which includes at least 2 temperature fluctuations within ±30℃ of the target temperature, each fluctuation lasting for 10-60 minutes; third stage: under the protection of a reducing atmosphere, the temperature is programmed to decrease to 700-1000℃ at a rate of 0.5-3℃ / min, and then the furnace is cooled to room temperature to obtain the sintered product. 8.The preparation method of the single-matrix three-doped white fluorescent material according to claim 7, characterized in that, in the precursor preparation step, the M source compound is an oxalate or an alkali carbonate of M; the aluminum source is boehmite, pseudo-boehmite, aluminum isopropoxide or aluminum nitrate; the cerium source is cerous nitrate, cerous acetate or cerous oxalate; the terbium source is terbium nitrate, terbium acetate or terbium chloride; The manganese source is manganese acetate, manganese nitrate or manganese sulfate. The manganese source is manganese acetate, manganese nitrate or manganese sulfate.

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