High-efficiency high-thermal-stability high-color-rendering-index composite fluorescent ceramic for solid-state lighting and preparation method thereof

Abstract

The application discloses a kind of high efficiency high thermal stability high color rendering index composite fluorescent ceramic for solid-state lighting and a preparation method thereof.The composite fluorescent ceramic has a three-layer composite structure, which comprises, from top to bottom, a red fluorescent film, a high light efficiency yellow-green fluorescent ceramic as a substrate, and a copper heat sink.The preparation method comprises the following steps: preparing the high light efficiency yellow-green fluorescent ceramic by batching, tabletting and vacuum sintering; mixing red fluorescent glass powder with an organic binder to obtain a fluorescent glass colloid; spin-coating the fluorescent glass colloid on the surface of the high light efficiency yellow-green fluorescent ceramic, and placing it in an oven for heat preservation to obtain a composite fluorescent glass-ceramic; and fixing the composite fluorescent glass-ceramic on the copper heat sink after sintering.The method can realize good connection and compounding between different ceramic substrates and the copper heat sink, and has the advantages of simple process, low cost and industrial production.The prepared composite fluorescent ceramic has the characteristics of high light efficiency, high thermal stability and high color rendering index.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of inorganic luminescent materials, and particularly relates to a high-efficiency high-thermal-stability high-color-rendering-index composite fluorescent ceramic for solid-state lighting and a preparation method thereof. BACKGROUND

[0002] Under the background of energy shortage and environmental problems becoming increasingly serious, since solid-state lighting has many advantages such as energy saving, high light efficiency, long service life and the like, countries all over the world are developing more energy-saving and efficient green lighting and display technologies. It is well known that the working temperature of the core device in a high-power white light LED / LD can be as high as 200℃, which puts a very high requirement on the thermal performance of the color converter. At present, the main phosphor converter used in commercial white light LEDs is made by mixing YAG:Ce phosphor and silicone. However, due to the low thermal conductivity (0.1-0.4 W / mK) of the traditional packaging material, they have yellowing and aging problems under high excitation power density, resulting in a decrease in light efficiency and color drift. As an increasingly popular alternative to traditional phosphor, glass phosphor (PiG) in which phosphor is dispersed in a glass matrix has been recently reported. PiG has the advantages of low cost, easy manufacturing and spatial construction diversification. Document 1 “Zhu Q Q, Xu X, Wang L, et al. A robust red-emitting phosphor-in-glass (PiG) for use in white lighting sources pumped by blue laser diodes [J]. Journal of Alloys and Compounds, 2017, 702: 193-198.” made CaAlSiN3:Eu PiG, and obtained a maximum luminous flux of 39 lm under an input power density of 0.5 W mm -2 Document “Yu J, Si S, Liu Y, et al. High-power laser-driven phosphor-in-glass for excellently high conversion efficiency white light generation for special illumination or display backlighting [J]. Journal of Materials Chemistry C, 2018, 6(30): 8212-8218.” pointed out that YAG-PiG has better thermal resistance than YAG-PiS (Phosphor-in-silicone), but the luminous flux of 467 lm and the conversion efficiency of 102.4 lm W -1The initial luminous efficiency of the PiG is not ideal. The PiG still has two serious problems: low power density and poor thermal conductivity of the glass matrix (~1 W / mK). SUMMARY

[0003] The present application aims to provide a high-efficiency high-thermal-stability high-color-rendering-index composite fluorescent ceramic for solid-state lighting and a preparation method thereof, which can realize good connection and compounding between different ceramic matrices and copper heat sinks, has simple process, low cost, and can realize industrialized production; the prepared composite fluorescent ceramic can have the characteristics of high light efficiency, high thermal stability and high color rendering index.

[0004] The technical scheme adopted by the present application is as follows: the present application provides a high-efficiency high-thermal-stability high-color-rendering-index composite fluorescent ceramic for solid-state lighting, which has a three-layer composite structure and is composed of a red fluorescent film, a high-efficiency yellow-green fluorescent ceramic as a matrix and a copper heat sink from top to bottom. 1.8 Al 4.2 Si 5.1 O 18 :yEu 3+ , wherein y is the mass percentage of Eu 3+ in Mg 1.8 Al 4.2 Si 5.1 O 18 , 0.01≤y≤0.04; the chemical formula of the high-efficiency yellow-green fluorescent ceramic is (Ce 0.003 Lu 0.997 )3(Mg x Al 1-2x Si x )5O 12 , wherein x is the mole percentage of magnesium ions and silicon ions replacing aluminum ions, 0.05≤x≤0.2.

[0005] Preferably, the chemical formula of the red fluorescent glass powder is Mg 1.8 Al 4.2 Si 5.1 O 18 :0.02Eu 3+ .

[0006] To achieve the above-mentioned application purposes, the present application further provides a preparation method of the above-mentioned high-efficiency high-thermal-stability high-color-rendering-index composite fluorescent ceramic for solid-state lighting, which comprises the following steps:

[0007] S1, preparing a high-efficiency yellow-green fluorescent ceramic;

[0008] S1-1, batching: taking lutetium oxide, aluminum oxide and cerium oxide as raw material powders, and according to the chemical formula (Ce0.003 Lu 0.997 )3(Mg x Al 1-2x Si x )5O 12 The stoichiometric ratio of corresponding elements in the formula is used to take each raw material, wherein x is the mole percentage of magnesium ions and silicon ions replacing aluminum ions, 0.05≤x≤0.2; then 0.05-0.20wt% of MgO and 0.4-1.0wt% of TEOS as sintering aids are added to the total mass of the raw material powder, and after ball milling and mixing, drying and sieving, the mixed powder is obtained;

[0009] S1-2, tabletting: the mixed powder after sieving is ball-mixed with dispersant ammonium citrate and anhydrous ethanol, then binder polyvinyl butyral ester and plasticizer glycerol are added and ball-mixed, to obtain slurry, and vacuum defoaming is performed; the slurry after defoaming is subjected to flow casting to obtain ceramic green sheet, and cold isostatic pressing is performed at 200-260MPa to obtain ceramic green body;

[0010] S1-3, vacuum sintering: the ceramic green body is placed in a vacuum sintering furnace and sintered at 1720-1780℃ for 5-8h, and finally double-sided polishing is performed to obtain high light efficiency yellow-green fluorescent ceramic;

[0011] S2, preparation of fluorescent glass colloid: the red fluorescent glass powder is mixed with organic binder, and stirred at 50-65℃ at a speed of 260-290rpm for 1-2.5h to obtain fluorescent glass colloid;

[0012] S3, coating: the fluorescent glass colloid prepared in step S2 is spin-coated on the surface of the high light efficiency yellow-green fluorescent ceramic prepared in step S2 at a speed of 500-800rpm to obtain a coating layer of 30-60um thickness, and then placed in an oven at 50-65℃ for 4-7h to obtain composite fluorescent glass-ceramic;

[0013] S4, sintering: the composite fluorescent glass-ceramic is placed in a muffle furnace and heated at 780-840℃ for 1-2.5h, and then heated at 980-1040℃ for 1-2.5h, and then fixed on a copper heat sink to obtain composite fluorescent ceramic.

[0014] Preferably, in step S1-2, the mass of the dispersant, anhydrous ethanol, binder, and plasticizer is 2-8wt%, 100-160wt%, 0.5-1.0wt%, and 0.05-0.20wt% of the mass of the mixed powder, respectively.

[0015] Preferably, in step S2, the organic binder is a mixture of ethyl cellulose, diethylene glycol monobutyl ether acetate, and terpineol, which is 40-60wt%, 20-40wt%, and 20-50wt% of the mass of the red fluorescent glass powder, respectively.

[0016] Compared with the prior art, the present application has the following beneficial effects:

[0017] 1、 the present application adopts yellow-green light emitting LuAG: Ce ceramic material as the substrate, has high luminous efficiency and excellent thermal stability; at the same time, the introduction of red fluorescent glass powder supplements the red light component, through the regulation of the thickness of different fluorescent glass powder coating layer, the accurate control of the luminous color and brightness can be realized, thereby improving the overall color rendering index. When the laser excitation power density is 10-40W / mm 2 , the maximum luminous efficiency is 170-180lm / W, and the color rendering index is 84-90; the luminous intensity at 473K temperature still maintains 98.95% of that at room temperature.

[0018] 2、 the present application adopts copper plate as the heat sink, the high thermal conductivity of copper enables it to quickly conduct the heat generated by the composite fluorescent ceramic to the surrounding air, avoids the damage to the device caused by excessively high temperature, thereby improving the performance of the device and prolonging its service life.

[0019] 3、 the present application adopts flow casting, glass spin coating and glass crystallization technologies, can realize the good connection and composite between different ceramic substrates and heat sinks, and the process is simple and low in cost; not only can improve the controllability and repeatability of the preparation process, but also can effectively control the density and structural stability of the material, thereby realizing large-scale industrialization. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 It is the SEM diagram of the composite fluorescent ceramic prepared in example 1 of the present application;

[0021] Figure 2 It is the luminous efficiency diagram of the composite fluorescent ceramic prepared in examples 1-4 of the present application;

[0022] Figure 3 It is the temperature spectrum data diagram of the composite fluorescent ceramic prepared in example 3 of the present application;

[0023] Figure 4 It is the color coordinate diagram of the composite fluorescent ceramic prepared in examples 1-4 of the present application. DETAILED DESCRIPTION

[0024] The present application will be further described in detail below in combination with the drawings and specific examples.

[0025] Example 1

[0026] The application discloses a high-efficiency high-thermal-stability high-color-rendering-index composite fluorescent ceramic for solid-state lighting, which has a three-layer composite structure from top to bottom, namely a red fluorescent film, a high-efficiency yellow-green fluorescent ceramic as a base and a heat sink. 1.8 Al 4.2 Si 5.1 O 18 :0.01Eu 2+ ; and a chemical formula of the high-efficiency yellow-green fluorescent ceramic is (Ce 0.003 Lu 0.997 )3(Mg 0.05 Al 0.9 Si 0.05 )5O 12 .

[0027] The application further discloses a preparation method of the high-efficiency high-thermal-stability high-color-rendering-index composite fluorescent ceramic for solid-state lighting.

[0028] S1, preparing the high-efficiency yellow-green fluorescent ceramic;

[0029] S1-1, dosing: taking lutetium oxide, aluminum oxide and cerium oxide as raw material powders, and taking each raw material according to a stoichiometric ratio of corresponding elements in a chemical formula (Ce 0.003 Lu 0.997 )3(Mg 0.05 Al 0.9 Si 0.05 )5O 12 ; then adding 0.05wt% of MgO and 0.4wt% of TEOS as sintering aids, ball-milling, drying, sieving and obtaining a mixed powder;

[0030] S1-2, tabletting: ball-milling the sieved mixed powder with 2wt% of a dispersant ammonium citrate and 100wt% of anhydrous ethanol, then adding 0.5wt% of a binder polyvinyl butyral ester and 0.05wt% of a plasticizer glycerol, continuously ball-milling to obtain a slurry, and performing vacuum degassing; performing flow casting on the slurry after degassing to obtain a ceramic green sheet, and performing cold isostatic pressing on the ceramic green sheet under 200MPa to obtain a ceramic green body;

[0031] S1-3, vacuum sintering: placing the ceramic green body into a vacuum sintering furnace and vacuum sintering at 1720℃ for 5h, and finally performing double-side polishing on the high-efficiency yellow-green fluorescent ceramic;

[0032] S2, preparing fluorescent glass colloid: 1 g of fluorescent glass powder is mixed with 40 wt% ethyl cellulose, 20 wt% diethylene glycol monobutyl ether acetate and 50 wt% terpineol, and then stirred at 55°C for 1 h at a speed of 260 rpm to obtain fluorescent glass colloid;

[0033] S3, coating: the fluorescent glass colloid prepared in step S2 is spin-coated on the high light efficiency yellow-green fluorescent ceramic surface prepared in step S2 at a rotation speed of 500 rpm to obtain a coating layer with a thickness of 60 um, and then placed in an oven for 4 h at 50°C to obtain a composite fluorescent glass-ceramic;

[0034] S4, sintering: the composite fluorescent glass-ceramic is placed in a muffle furnace and heated at 780°C for 1 h to make the glass fully bond to the fluorescent ceramic, and then heated at 980°C for 1 h to make the glass fully crystallize, and finally fixed on a copper heat sink to obtain a composite fluorescent ceramic.

[0035] The SEM of the composite fluorescent ceramic prepared in this example is shown in Figure 1 , the upper layer is the crystallized red fluorescent film layer, and the lower layer is the yellow-green LuAG:Ce ceramic layer, which are tightly connected together; the luminous efficiency diagram is shown in Figure 2 , the maximum luminous efficiency is 172 lm / W when the laser excitation power density is 20 W / mm 2 ; as shown in Figure 4 , the color rendering index of the composite fluorescent ceramic is 84.

[0036] Example 2

[0037] A high-efficiency high-thermal-stability high-color-rendering-index composite fluorescent ceramic for solid-state lighting, which has a three-layer composite structure from top to bottom, i.e., a red fluorescent film, a high light efficiency yellow-green fluorescent ceramic as a substrate, and a heat sink; the raw material of the red fluorescent film is red fluorescent glass powder, and the chemical formula of the red fluorescent glass powder is Mg 1.8 Al 4.2 Si 5.1 O 18 :0.02Eu 3+ ; the chemical formula of the high light efficiency yellow-green fluorescent ceramic is (Ce 0.003 Lu 0.997 )3(Mg 0.1 Al 0.8 Si 0.1 )5O 12 .

[0038] The preparation method of the above-mentioned high-efficiency high-thermal-stability high-color-rendering-index composite fluorescent ceramic for solid-state lighting comprises the following steps:

[0039] S1, preparing a high light efficiency yellow-green fluorescent ceramic;

[0040] S1-1, Ingredients: Lutene oxide, aluminum oxide, and cerium oxide are used as raw material powders, according to the chemical formula (Ce... 0.003 Lu 0.997 )3(Mg 0.1 Al 0.8 Si 0.1 )5O 12 Weigh each raw material according to the stoichiometric ratio of the corresponding elements; then add 0.1 wt% MgO and 0.6 wt% TEOS as sintering aids, ball mill and mix, dry and sieve to obtain mixed powder;

[0041] S1-2, Compressing: The sieved mixed powder is ball-milled with 4 wt% ammonium citrate dispersant and 120 wt% anhydrous ethanol, then 0.6 wt% polyvinyl butyral binder and 0.1 wt% glycerol plasticizer are added, and ball milling continues to obtain a slurry, which is then degassed under vacuum. The degassed slurry is then cast into ceramic blanks, which are then cold isostatically pressed at 220 MPa to obtain ceramic blanks.

[0042] S1-3, Vacuum sintering: Place the ceramic blank into a vacuum sintering furnace and sinter it at 1740℃ for 6 hours. Finally, perform double-sided polishing to produce high-gloss yellow-green fluorescent ceramic.

[0043] S2. Preparation of fluorescent glass colloid: 2g of fluorescent glass powder was mixed with 45wt% ethyl cellulose, 25wt% diethylene glycol monobutyl ether acetate and 40wt% terpineol by weight of fluorescent glass powder, and stirred at 270rpm for 1.5h at 55℃ to obtain fluorescent glass colloid.

[0044] S3. Coating: The fluorescent glass colloid prepared in step S2 is spin-coated onto the surface of the high-efficiency yellow-green fluorescent ceramic prepared in step S2 at a speed of 600 rpm to obtain a coating layer with a thickness of 50 μm. Then, it is placed in an oven and kept at 55°C for 5 h to obtain a composite fluorescent glass-ceramic.

[0045] S4. Sintering: The composite fluorescent glass-ceramic is placed in a muffle furnace and held at 800℃ for 1.5h to allow the glass to fully bond to the fluorescent ceramic. Then, it is held at 1000℃ for 1.5h to allow the glass to fully crystallize. Finally, it is fixed on a copper heat sink to obtain the composite fluorescent ceramic.

[0046] The luminescence efficiency of the composite fluorescent ceramic prepared in this embodiment is shown in the figure below. Figure 2 As shown, the laser excitation power density is 20 W / mm². 2 At that time, the maximum luminous efficiency was 175 lm / W. For example... Figure 3 As shown, the luminescence intensity remains 98.95% of its room temperature value at 473K.Figure 4 The color rendering index is 86.

[0047] Embodiment 3

[0048] A high-efficiency high-thermal-stability high-color-rendering-index composite fluorescent ceramic for solid-state lighting, which has a three-layer composite structure from top to bottom of a red fluorescent film, a high-efficiency yellow-green fluorescent ceramic as a base, and a heat sink; the red fluorescent film is made of red fluorescent glass powder, and the chemical formula of the red fluorescent glass powder is Mg 1.8 Al 4.2 Si 5.1 O 18 :0.03Eu 3+ ; the high-efficiency yellow-green fluorescent ceramic has a chemical formula of (Ce 0.003 Lu 0.997 )3(Mg 0.15 Al 0.7 Si 0.15 )5O 12 .

[0049] The preparation method of the high-efficiency high-thermal-stability high-color-rendering-index composite fluorescent ceramic for solid-state lighting, which comprises the following steps:

[0050] S1, preparing a high-efficiency yellow-green fluorescent ceramic;

[0051] S1-1, batching: taking lanthanum oxide, aluminum oxide, and cerium oxide as raw material powders, and taking each raw material according to the stoichiometric ratio of the corresponding elements in the chemical formula (Ce 0.003 Lu 0.997 )3(Mg 0.15 Al 0.7 Si 0.15 )5O 12 ; then adding 0.15wt% of MgO and 0.8wt% of TEOS as sintering aids, ball-milling, drying, and sieving to obtain a mixed powder;

[0052] S1-2, tabletting: ball-milling the sieved mixed powder with 6wt% of a dispersant ammonium citrate and 140wt% of anhydrous ethanol, then adding 0.8wt% of a binder polyvinyl butyral ester and 0.15wt% of a plasticizer glycerol, continuing to ball-mill to obtain a slurry, and performing vacuum debubbling; performing flow casting of the slurry after debubbling to obtain ceramic green sheet, and performing cold isostatic pressing at 240MPa to obtain a ceramic green body;

[0053] S1-3, vacuum sintering: placing the ceramic green body into a vacuum sintering furnace and sintering at 1760℃ for 7h, and finally polishing the high-efficiency yellow-green fluorescent ceramic on both sides;

[0054] S2, preparing fluorescent glass colloid: 3 g of fluorescent glass powder is mixed with 50 wt% ethyl cellulose, 30 wt% diethylene glycol monobutyl ether acetate and 30 wt% terpineol, and then stirred at 60°C for 2 h at a speed of 280 rpm to obtain fluorescent glass colloid;

[0055] S3, coating: the fluorescent glass colloid prepared in step S2 is spin-coated on the high light efficiency yellow-green fluorescent ceramic surface prepared in step S2 at a rotation speed of 700 rpm to obtain a coating layer with a thickness of 40 um, and then placed in an oven for 6 h at 60°C to obtain a composite fluorescent glass-ceramic;

[0056] S4, sintering: the composite fluorescent glass-ceramic is placed in a muffle furnace for 2 h at 820°C to make the glass fully bonded on the fluorescent ceramic, and then sintered at 1020°C for 2 h to make the glass fully crystallized, and finally fixed on a copper heat sink to obtain a composite fluorescent ceramic.

[0057] The light emitting efficiency diagram of the composite fluorescent ceramic prepared in this embodiment is shown in Figure 2 , and the maximum light emitting efficiency is 178 lm / W when the laser excitation power density is 20 W / mm 2 . As shown in Figure 4 , the color rendering index is 90.

[0058] Example 4

[0059] A high-efficiency high-thermal-stability high-color-rendering-index composite fluorescent ceramic for solid-state lighting, which has a three-layer composite structure from top to bottom, i.e., a red fluorescent film, a high light efficiency yellow-green fluorescent ceramic as a substrate, and a heat sink; the raw material of the red fluorescent film is red fluorescent glass powder, and the chemical formula of the red fluorescent glass powder is Mg 1.8 Al 4.2 Si 5.1 O 18 :0.04Eu 3+ ; the chemical formula of the high light efficiency yellow-green fluorescent ceramic is (Ce 0.003 Lu 0.997 )3(Mg 0.2 Al 0.3 Si 0.2 )5O 12 .

[0060] The preparation method of the above-mentioned high-efficiency high-thermal-stability high-color-rendering-index composite fluorescent ceramic for solid-state lighting comprises the following steps:

[0061] S1, preparing a high light efficiency yellow-green fluorescent ceramic;

[0062] S1-1, batching: using lutetium oxide, aluminum oxide and cerium oxide as raw material powder, and the chemical formula is (Ce 0.003Lu 0.997 )3(Mg 0.2 Al 0.3 Si 0.2 )5O 12 The stoichiometric ratio of corresponding elements in the middle was taken for each raw material; 0.2wt% of MgO and 1.0wt% of TEOS as sintering aids were added to the total mass of the raw material powder, and after ball milling and mixing, drying and sieving, the mixed powder was obtained;

[0063] S1-2, tabletting: the mixed powder after sieving was ball-mixed with 8wt% of dispersant ammonium citrate and 160wt% of anhydrous ethanol, followed by the addition of 1.0wt% of binder polyvinyl butyral ester and 0.2wt% of plasticizer glycerol, and the ball-mixing was continued to obtain a slurry, and vacuum defoaming was performed; the slurry after defoaming was subjected to flow casting to obtain ceramic green sheet, and cold isostatic pressing was performed at 260MPa to obtain ceramic green body;

[0064] S1-3, vacuum sintering: the ceramic green body was placed in a vacuum sintering furnace and vacuum sintered at 1780℃ for 8h, and finally double-sided polishing was performed to obtain high-efficiency yellow-green fluorescent ceramic;

[0065] S2, preparation of fluorescent glass colloid: 4g of fluorescent glass powder was mixed with 55wt% of ethyl cellulose, 35wt% of diethylene glycol monobutyl ether acetate and 20wt% of terpineol, and stirring was performed at 65℃ for 2.5h at a speed of 290rpm to obtain fluorescent glass colloid;

[0066] S3, coating: the fluorescent glass colloid prepared in step S2 was spin-coated on the surface of the high-efficiency yellow-green fluorescent ceramic prepared in step S2 at a rotation speed of 800rpm to obtain a coating layer of 30um in thickness, and then it was placed in an oven and kept at 65℃ for 7h to obtain composite fluorescent glass-ceramic;

[0067] S4, sintering: the composite fluorescent glass-ceramic was placed in a muffle furnace and kept at 840℃ for 2.5h to make the glass fully bonded on the fluorescent ceramic, and then it was kept at 1040℃ for 2.5h to make the glass fully crystallized, and finally it was fixed on a copper heat sink to obtain composite fluorescent ceramic.

[0068] The luminous efficiency diagram of the composite fluorescent ceramic prepared in this embodiment is shown in Figure 2 , and the maximum luminous efficiency is 177lm / W when the laser excitation power density is 20W / mm 2 . As shown in Figure 4 , the color rendering index is 88.

[0069] The above merely illustrates the specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any modification, equivalent replacement and improvement within the technical range disclosed by the present application and within the spirit and principle of the present application should be covered within the protection scope of the present application.

Claims

1. A high efficiency high thermal stability high color rendering index composite fluorescent ceramic for solid state lighting, characterized in that, The composite fluorescent ceramic has a three-layer composite structure, from top to bottom, a red fluorescent film, a high light efficiency yellow-green fluorescent ceramic as a base and a copper heat sink; the raw material of the red fluorescent film is red fluorescent glass powder, and the chemical formula of the red fluorescent glass powder is Mg 1.8 Al 4.2 Si 5.1 O 18 :yEu 3+ , wherein y is the mass percentage of Eu 3+ in Mg 1.8 Al 4.2 Si 5.1 O 18 , and 0.01≤y≤0.04; the chemical formula of the high light efficiency yellow-green fluorescent ceramic is (Ce 0.003 Lu 0.997 )3(Mg x Al 1-2x Si x )5O 12 , wherein x is the mole percentage of magnesium ions and silicon ions replacing aluminum ions, and 0.05≤x≤0.

2.

2. The high efficiency, high thermal stability, high color rendering index composite fluorescent ceramic for solid state lighting according to claim 1, characterized in that, The chemical formula of the red fluorescent glass powder is Mg 1.8 Al 4.2 Si 5.1 O 18 :0.02Eu 3+ .

3. A method for preparing the high efficiency high thermal stability high color rendering index composite fluorescent ceramic for solid state lighting according to claim 1 or 2, characterized in that, The method comprises the following steps: S1, preparing high light efficiency yellow-green fluorescent ceramic; S1-1, batching: taking Lu2O3, Al2O3 and CeO2 as raw material powders, and taking each raw material according to the stoichiometric ratio of corresponding elements in the chemical formula (Ce 0.003 Lu 0.997 )3(Mg x Al 1-2x Si x )5O 12 , wherein x is the mole percentage of magnesium ions and silicon ions substituting aluminum ions, and 0.05≤x≤0.2; then adding 0.05-0.20wt% of MgO and 0.4-1.0wt% of TEOS as sintering aids to the total mass of the raw material powders, ball-milling, drying and sieving to obtain the mixed powders; S1-2, tabletting: the sieved mixed powder is mixed with dispersant ammonium citrate and anhydrous ethanol by ball milling, then binder polyvinyl butyral ester and plasticizer glycerol are added and continue to be ball milled to obtain slurry, and vacuum defoaming is performed; the defoamed slurry is subjected to flow casting to obtain ceramic green sheet, and cold isostatic pressing is performed at 200-260 MPa to obtain ceramic green body; S1-3, vacuum sintering: the ceramic green body is placed in a vacuum sintering furnace and sintered at 1720-1780℃ for 5-8h, and finally double-sided polishing is performed to obtain high light efficiency yellow-green fluorescent ceramic; S2, preparing fluorescent glass colloid: the red fluorescent glass powder is mixed with an organic binder, and stirred at 50-65℃ at a speed of 260-290rpm for 1-2.5h to obtain fluorescent glass colloid; S3, coating: the fluorescent glass colloid prepared in step S2 is spin-coated on the surface of the high light efficiency yellow-green fluorescent ceramic prepared in step S1 at a speed of 500-800rpm to obtain a coating layer with a thickness of 30-60um, and then placed in an oven and heated at 50-65℃ for 4-7h to obtain composite fluorescent glass-ceramic; S4, sintering: the composite fluorescent glass-ceramic is placed in a muffle furnace and heated at 780-840℃ for 1-2.5h, then heated at 980-1040℃ for 1-2.5h, and then fixed on a copper heat sink to obtain composite fluorescent ceramic.

4. The method for preparing a high efficiency high thermal stability high color rendering index composite fluorescent ceramic for solid state lighting according to claim 3, characterized in that, In step S1-2, the mass of the dispersant, anhydrous ethanol, binder and plasticizer is 2-8wt%, 100-160wt%, 0.5-1.0wt% and 0.05-0.20wt% of the mass of the mixed powder, respectively.

5. The method for preparing a high efficiency high thermal stability high color rendering index composite fluorescent ceramic for solid state lighting according to claim 3 or 4, characterized in that, In step S2, the organic binder is a mixture of ethyl cellulose, diethylene glycol monobutyl ether acetate and terpineol, which is 40-60wt%, 20-40wt% and 20-50wt% of the mass of the red fluorescent glass powder, respectively.

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