Fluorescent cone embedded hexagonal array composite structure fluorescent ceramic as well as preparation method and application thereof

Abstract

The invention discloses a fluorescent cone embedded hexagonal array composite structure fluorescent ceramic as well as a preparation method and application thereof. According to the composite structure fluorescent ceramic, ceramic with the component being T serves as a base body, cone fluorescent ceramic units which are arranged in order are constructed in the base body through the combination of the gel technology and the photocuring 3D printing technology, and finally the fluorescent cone embedded hexagonal array composite structure fluorescent ceramic is formed. The problem of light spot expansion of the fluorescent ceramic is effectively solved by accurately regulating and controlling the matching relationship between the size of the conical bottom surface and the incident laser light spot and utilizing the synergistic effect generated by the optical characteristic difference between the ceramic matrix and the fluorescent ceramic. In addition, a three-dimensional efficient heat conduction network is formed between the ceramic matrix and the fluorescent ceramic, and heat accumulated under excitation of high-power-density laser can be quickly dissipated. The composite structure fluorescent ceramic with the fluorescent cone embedded into the hexagonal array can realize high-collimation, high-efficiency and high-brightness luminescence, and can be widely applied to the fields of laser illumination and display after being packaged with a laser excitation source.

Description

Technical Field

[0001] The present invention belongs to the technical fields of preparation of fluorescent ceramics and laser lighting and display, and particularly relates to a fluorescent cone-embedded hexagonal array composite structure fluorescent ceramic with a function of spot control and optimized photothermal performance, and further discloses a preparation method and application thereof. Background Art

[0002] Based on blue laser diode (LD) fluorescent conversion type solid-state lighting devices, with their advantages of high luminous efficiency, energy conservation and environmental protection, etc., have been applied on a large scale in the fields of automotive headlights, military lighting, laser projectors and outdoor lighting, etc. Compared with the technically mature LED light sources, blue LD not only avoids the "efficiency decline" phenomenon of traditional LEDs, but also shows unique advantages of an extremely small emission area and a lower beam divergence, so it is recognized as the core light source of the next-generation lighting source. However, the severe heat deposition and periodic thermal shock caused by blue LD during high-power density operation pose new challenges to the intrinsic thermal stability and interface reliability of fluorescent materials. For this reason, fluorescent ceramics with excellent heat resistance, high quantum efficiency and stable physical and chemical properties have emerged. Nevertheless, when facing the demand for high-power laser lighting, fluorescent ceramics expose problems such as spot expansion, serious heat accumulation, and attenuation of light extraction efficiency in practical applications, which greatly limit their applications in the lighting and display fields.

[0003] At present, Literature 1 (Journal of the European Ceramic Society, 2022, 42(2): 608-615.) proposed a porous microstructure YAG:Ce / glass composite film, and realized spot limitation by using the refractive index difference between air and phosphor. However, introducing air holes inside will reduce the heat dissipation performance of the fluorescent material, which is not suitable for high-power and high-brightness laser lighting. Literature 2 (Laser Photonics Rev, 2019, 13(10)1900147-1-10) greatly reduced the size of the spot by introducing uniformly distributed air holes as light scattering centers. The spot diameter was reduced by 46%, and the central brightness was increased by 156%. However, the existence of micro air holes will seriously deteriorate the thermal conductivity and high-temperature luminescence stability of the fluorescent ceramic. Sang et al. (Optics Express, 2022, 30(22): 40951-40964.) introduced Al 2 O 3 -YAG:Ce ceramics with the same size as the incident laser spot size into disk-shaped YAG ceramics to improve their luminous performance. However, the converted light in the ceramic light-emitting area escapes from YAG, resulting in the expansion of its luminous spot.

[0004] Wang et al. (Laser & Photonics Reviews, 18(2024).) constructed a sandwich - structured composite phosphor by covering a layer of Al 2 O 3 film on the YAGG:Ce film of the sapphire substrate. Thanks to the scattering of the Al 2 O 3 film, the luminescence uniformity was significantly improved, but the effect of the Al 2 O 3 film on the light - emitting spot was not demonstrated. Wang et al. (Journal of Alloys and Compounds 1010(2025)177779) proposed introducing ZnO particles with high thermal conductivity and high refractive index into YAG:Ce PiGF, and confirmed that adding ZnO powder could enhance heat dissipation and improve luminescence uniformity. However, this literature was only used to improve the heat dissipation performance and luminescence uniformity of fluorescent materials.

[0005] Chinese Patent CN116768628A proposed a method for preparing an array - cored composite - structure fluorescent ceramic based on gel - casting molding technology. This composite - structure fluorescent ceramic realized effective regulation of the light spot by utilizing the refractive index difference between two ceramics. Although this design has advantages in optical performance, its heat dissipation performance is poor, and the preparation process is complex, making it difficult to meet the requirements of industrial production.

[0006] Chinese Patent CN 118206369 A prepared a composite - structure fluorescent ceramic by combining 3D printing and photocuring technology. This structure utilized the total reflection effect generated by the refractive index difference between the outer skin layer and the phosphor to solve the problem of out - of - control light spots. However, the luminous efficiency and luminescence uniformity of this structure of fluorescent ceramic are not satisfactory.

[0007] Chinese Patent CN 117209275A disclosed a preparation method of a laser - transparent ceramic with concentration - gradient doping, using gel - casting molding technology combined with vacuum sintering of Lu 3 Al 5 O 12 ceramics. By changing the concentration - gradient variation of the doping elements in the transparent ceramic, the light output consistency was improved. However, the ceramics prepared by this method were limited to preparing a small number of concentration - gradient ceramics, which was not conducive to industrial production.

[0008] Chinese Patent CN 110108163 A disclosed a self - constrained ceramic panel structure, which has significant advantages in improving bullet - proof performance and simplifying structural design, especially suitable for the armored protection field that requires high bullet - proof performance. However, it has high requirements for manufacturing precision, maintenance cost, and environmental adaptability.

[0009] Chinese Invention Patent CN 118108495 A proposes a reflective laser illumination composite fluorescent ceramic. By using laser engraving to form a conical structure array at the YAG on the surface of the composite ceramic, the luminous efficiency of the composite fluorescent ceramic is improved. However, the local high temperature during laser engraving may cause too large a temperature difference between the surface and the interior of the ceramic, generating thermal stress. The ceramic itself has high brittleness and is prone to form microcracks, reducing the mechanical strength and durability of the material.

[0010] In summary, there are problems such as spot expansion, serious heat accumulation, attenuation of light extraction efficiency, etc. in the fluorescent ceramics for laser illumination at present, which seriously limit the exertion and development of the advantages of laser illumination. Therefore, it is urgent to develop fluorescent ceramics with controllable spots and excellent photothermal properties. Summary of the Invention

[0011] The technical problem to be solved by the present invention is that the fluorescent ceramic has problems such as spot expansion, serious heat accumulation, attenuation of light extraction efficiency, and poor luminous uniformity. A fluorescent cone-embedded hexagonal array composite structure fluorescent ceramic and its preparation method and application are provided, so as to solve the problems of spot expansion, serious heat accumulation, attenuation of light extraction efficiency, and poor luminous uniformity of the fluorescent ceramic, and achieve high collimation, high efficiency, and high brightness light emission.

[0012] The fluorescent cone-embedded hexagonal array composite structure fluorescent ceramic provided by the present invention effectively solves the problem of spot expansion of the fluorescent ceramic by using the synergistic effect of the size relationship between the bottom surface of the cone and the incident laser spot and the optical property difference between the hexagonal ceramic matrix and the conical fluorescent ceramic.

[0013] The fluorescent cone-embedded hexagonal array composite structure fluorescent ceramic provided by the present invention, by optimizing the geometric matching relationship between the Ce 3+ concentration gradient distribution in the fluorescent ceramic and the laser energy distribution, and combining the total internal reflection suppression characteristics of the conical structure, significantly improves the light extraction efficiency and luminous uniformity of the ceramic.

[0014] The fluorescent cone-embedded hexagonal array composite structure fluorescent ceramic provided by the present invention, the main structure of this structural ceramic is composed of ZnO or Al 2 O 3 or AlN. An efficient heat conduction network with three-dimensional interconnection is formed between the hexagonal ceramic matrix and the fluorescent ceramic through interface optimization, which can greatly reduce the heat accumulation under the excitation of high-power density laser, thereby breaking through the limitation of the thermal quenching effect.

[0015] The present invention also provides a preparation method of the fluorescent cone-embedded hexagonal array composite structure fluorescent ceramic. A variety of slurries are mixed in proportion through a microfluidic chip to achieve continuous change of concentration, and combined with the light-curing 3D printing technology for rapid prototyping. The whole preparation process is simple and controllable.

[0016] To solve the above technical problems, the present invention adopts the following technical solutions: A fluorescent conical body embedded hexagonal array composite structure fluorescent ceramic, the composite structure fluorescent ceramic includes hexagonal prism ceramic substrates arranged in an array, and conical fluorescent ceramics are directionally constructed and orderly arranged in the substrates. The composition of the ceramic substrate is T, and the composition of the fluorescent ceramic is L. Among them, T is one of ZnO, Al 2 O 3 and AlN; L is [(Y 0.99 Gd 0.01 ) 1-x Ce x 3 Al 5 O 12 , 0.001 ≤ x ≤ 0.05. In the fluorescent ceramic, Ce 3+ shows a concentration gradient distribution, and the specific concentration gradient distribution means that the concentration of Ce 3+ gradually increases from the bottom surface of the cone to the top of the cone.

[0017] Furthermore, the cross-sectional area of the ceramic substrate accounts for 40%-55% of the entire ceramic cross-sectional area. The diameter of the bottom surface of the cone of the conical fluorescent ceramic is 60 μm - 300 μm. The overall thickness, length, and width of the composite structure fluorescent ceramic are 1 mm - 2 mm, 1.0 mm - 1.5 mm, and 0.8 mm - 1.0 mm respectively.

[0018] Furthermore, in the fluorescent conical body embedded hexagonal array composite structure fluorescent ceramic, the concentration of Ce 3+ in the conical fluorescent ceramic shows a gradient distribution and satisfies geometric relationships (one) and (two) with the laser Gaussian energy distribution:

[0019]

[0020] Among them, C(r) is the concentration of Ce 3+ at a distance r from the center, C 0 is the central concentration, and σ c is the standard deviation of the concentration distribution;

[0021]

[0022] Among them, I(r) is the laser intensity at a distance r from the center, I 0 is the central intensity, and σ l is the standard deviation of the laser beam;

[0023] In order to make the Ce 3+ concentration distribution match the laser energy distribution, the relationship between the standard deviation σ c of the concentration distribution and the standard deviation σ l of the laser beam is adjusted, and the two satisfy σ c = kσ​l , where, when k = 1, the light conversion efficiency is the highest; when k < 1, the Ce 3+ concentration distribution is more concentrated, suitable for high local light intensity scenarios; when k > 1, the Ce 3+ concentration distribution is wider, suitable for uniform light output scenarios.

[0024] The present invention also provides a preparation method of the fluorescent cone embedded hexagonal array composite structure fluorescent ceramic. The gel technology is combined with the photocuring 3D printing technology to directionally construct orderly arranged cone-shaped fluorescent ceramic units in the hexagonal prism ceramic matrix arranged in an array, and finally form the fluorescent cone embedded hexagonal array composite structure fluorescent ceramic, which specifically includes the following steps:

[0025] (1) Prepare the ceramic green body by using the photocuring 3D printing technology combined with the gel technology: Print the gel slurry with the composition of T into a hexagonal prism ceramic matrix arranged in an array with cone-shaped grooves, introduce the fluorescent ceramic slurry with the composition of L into the cone-shaped grooves, and construct the fluorescent cone embedded hexagonal array composite structure ceramic green body;

[0026] (2) Subject the fluorescent cone embedded hexagonal array composite structure ceramic green body to preliminary sintering and then high-temperature sintering to obtain the fluorescent cone embedded hexagonal array composite structure fluorescent ceramic.

[0027] Furthermore, the method for printing the gel slurry with the composition of T into a hexagonal prism ceramic matrix arranged in an array with cone-shaped grooves in the step (1) is as follows:

[0028] ① Pre-dry the powder T, and then place the powder T, absolute ethanol and the surfactant ammonium oxide together in a ball milling tank, and ball mill for 1.5 - 3.5 h under the condition of a rotation speed of 180 - 260 r / min to prepare a suspension, where the powder T is at least one of ZnO, Al 2 O 3 and AlN. The particle size range of the powder T is 10 - 50 μm, the grinding balls are high-purity alumina balls with an average particle size of 10 - 50 μm, and the mass of the absolute ethanol is 2 - 4 times the mass of the powder T, and the mass of the surfactant ammonium oxide is 1 / 80 - 1 / 120 of the mass of the powder T; Use a rotary evaporator to remove the absolute ethanol in the suspension at a heating temperature of 60 - 80 °C, and then place it in an oven and heat-treat at 90 °C - 110 °C for 4 h - 7 h; After cooling to room temperature, grind the obtained powder and pass through a 150 - 200 mesh sieve to obtain the modified powder T;

[0029] ② Mix pentaerythritol tetraacrylate, 1,6 - hexanediol diacrylate, polyurethane acrylate, n - octanol, and polyethylene glycol to obtain a photocurable material, where the mass ratio of pentaerythritol tetraacrylate:1,6 - hexanediol diacrylate:polyurethane acrylate:n - octanol:polyethylene glycol is 20%:25%:20%:20%:15%. Add the photocurable material to deionized water to prepare a premixed solution. Subsequently, add the modified powder T from step ① and a dispersant BYK 9077 accounting for 3 wt% of the mass of powder T to the premixed solution, and ball - mill for 9 - 13 h under the condition of a rotation speed of 280 - 330 r / min to prepare a ceramic matrix slurry with a solid content of 48 vol% - 52 vol%.

[0030] ③ Add a photoinitiator Irgacure 819 accounting for 1 - 2 wt% of the total mass of the slurry to the ceramic matrix slurry, ball - mill for 12 - 15 min under the condition of a rotation speed of 280 - 330 r / min, and then place it in the material tank of a DLP 3D printer.

[0031] ④ Set the layer thickness of the printing parameters to 20 μm, the exposure energy density to 31.5 mj / cm 2 , and the single - layer curing time to 5 s. Use 3D modeling software to establish a three - dimensional model of the hexagonal ceramic matrix, import it into the printer through CeraRay software, and prepare a hexagonal prism ceramic green body with an array arrangement of conical grooves by layer - by - layer cumulative printing, and perform UV irradiation photocuring throughout the printing process to finally obtain a ceramic matrix.

[0032] Furthermore, in the conical groove in step (1), introduce a fluorescent ceramic slurry with a composition of L. The method for constructing a fluorescent ceramic green body with a composite structure of fluorescent cones embedded in a hexagonal array is as follows:

[0033] ① Mix CeO 2 , Y 2 O 3 , Gd 2 O 3 and Al 2 O 3 according to the chemical formula [(Y 0.99 Gd 0.01 ) 1-x Ce x 3 Al 5 O 12 , where 0.001 ≤ x ≤ 0.05, to obtain a mixed oxide powder. After ball - milling, drying, grinding, and sieving, obtain a fluorescent ceramic powder GdYAG:Ce; where CeO 2 , Y 2 O 3 , Gd 2 O 3 and Al​2 O 3 has a particle size range of 100 - 200 nm;

[0034] ② Prepare a premix by adding 1.0 wt% pH regulator tetramethylammonium hydroxide and 0.5 wt% dispersant ammonium citrate in deionized water. Add the fluorescent ceramic powder into the premix in 4 portions, and perform low-speed ball milling using an alumina ball milling tank. The ball milling speed is 50 r / min, the grinding balls are high-purity alumina balls, and the mass ratio of the fluorescent ceramic powder to the grinding balls is 1:3. After all the fluorescent ceramic powder is added to the premix, ball mill for 12 h to obtain a slurry. Among them, when adding the fluorescent ceramic powder to the premix in 4 portions for ball milling, the first addition amount is 25% of the mass of the fluorescent ceramic powder, the second to third addition amounts are 45% of the mass of the fluorescent ceramic powder, and the fourth addition amount is 30% of the mass of the fluorescent ceramic powder;

[0035] ③ Add a total of 0.8 wt% monomer acrylamide AM and crosslinking agent N,N'-methylenebisacrylamide to the slurry obtained in ②. The mass ratio of AM to N,N'-methylenebisacrylamide is 1 / 10, continue ball milling for 3 h, and perform degassing treatment on the ball-milled slurry to obtain a ceramic slurry with a solid content of 50 vol% - 55 vol%;

[0036] ④ Add 0.4 wt% photoinitiator Irgacure 819 to the ceramic slurry obtained in ③, and ball mill for 8 min under the condition of a rotation speed of 350 r / min to obtain a fluorescent ceramic slurry defined as slurry A, and then place it in the trough A of a DLP 3D printer;

[0037] ⑤ Prepare the ceramic powder GdYAG without Ce according to steps ① - ④, obtain a GdYAG ceramic slurry defined as slurry B, and then place it in the trough B of a DLP 3D printer; 3+ has a particle size range of 100 - 200 nm;

[0038] ⑥ Use 3D modeling software to establish a model of an array of conical fluorescent ceramics, define the gradient distribution of the Ce 3+ concentration in the model. Specifically, it means that the Ce 3+ concentration gradually increases from the bottom to the top of the cone. Slice the 3D model into n layers and assign a slurry to each layer. Subsequently, convey slurry A in trough A and slurry B in trough B to a microfluidic mixer. The microfluidic mixer dynamically adjusts the flow ratio between slurry A and slurry B according to a preset curve, outputs a mixed slurry with a target concentration, and finally the mixed slurry is conveyed to a print head, printed layer by layer on a ceramic substrate, and cured layer by layer to obtain a fluorescent conical body embedded in a hexagonal array composite structure fluorescent ceramic green body; the thickness of the slice is 10 - 20 μm; the layer thickness in the 3D printing parameters is the thickness of the slice, and the exposure energy density is 31.5 mj / cm 2, the single-layer curing time is 2 - 5 s. Among them, the concentration of slurry A is 100% C o , the concentration of slurry B is 0% C o , the concentration at the top of the cone is 100% C o , and it decreases layer by layer with a concentration gradient of . By controlling the volume flow ratio between slurry A and slurry B, a mixed slurry with the target concentration is output, such as 50% C o which is formed by uniformly mixing 1 / 2 of slurry A and 1 / 2 of slurry B.

[0039] Further, the specific operation of the biscuit firing in step (2) is as follows: Embed the fluorescent cone into the hexagonal array composite structure fluorescent ceramic green body and place it in an alumina crucible. Heat it at a heating rate of 0.5 °C / min - 1 °C / min to 360 °C - 380 °C and keep it warm for 13 h - 15 h, then heat it at a heating rate of 1.5 °C / min - 2 °C / min to 700 °C - 800 °C and keep it warm for 8 h - 10 h. Biscuit fire in a muffle furnace to remove the organic matter in the green body.

[0040] Further, the specific operation of the high-temperature sintering in step (2) is as follows: Heat the biscuit-fired composite structure fluorescent ceramic green body in an argon / nitrogen atmosphere at a heating rate of 0.5 °C / min - 1 °C / min to 1550 °C - 1650 °C and keep it warm for 10 - 12 h. After the heat preservation is completed, cool it to room temperature at a cooling rate of 0.5 °C / min - 1.0 °C / min to obtain the fluorescent cone embedded hexagonal array composite structure fluorescent ceramic.

[0041] Further, for the fluorescent cone embedded hexagonal array composite structure fluorescent ceramic of the present invention, the thermal conductivity is 20 - 200 Wm -1 K -1 , the Vickers hardness is as high as 1200 - 2000 HV, and the fracture toughness is as high as 1.5 - 3.5 MPa m 1 / 2 .

[0042] The present invention also provides the application of the fluorescent cone embedded hexagonal array composite structure fluorescent ceramic in the field of laser lighting. It is characterized in that under the excitation of a 450 nm blue laser with an emission peak, the beam expansion rate of the light-emitting spot is 15% - 64%, the beam expansion value is 30 - 128 μm, and the luminous efficiency is 228 - 321 lm / W.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] (1) The fluorescent conical-embedded hexagonal array composite structure fluorescent ceramic proposed by the present invention realizes the total reflection effect by precisely regulating the matching relationship between the bottom surface size of the cone and the incident laser spot, and utilizing the synergistic effect generated by the optical property difference between the hexagonal ceramic matrix and the fluorescent ceramic. Thereby, the light-gathering ability of the ceramic material is enhanced, the directivity of the laser light source is improved, and the problem of spot expansion is solved, realizing high-brightness, high-light-flux, and high-collimation white light emission.

[0045] (2) The fluorescent conical-embedded hexagonal array composite structure fluorescent ceramic proposed by the present invention enables the excitation beam to achieve multiple orderly optical path regulations inside the fluorescent ceramic through the optical property matching between the hexagonal ceramic matrix material and the fluorescent materials dispersed in the ceramic block. It effectively avoids the "yellow ring effect" caused by the un-scattered and un-converted incident blue light directly passing through the fluorescent ceramic, which affects the light output consistency. Thereby, the light extraction efficiency of the fluorescent ceramic is greatly improved, and the luminescence uniformity is improved.

[0046] (3) The fluorescent conical-embedded hexagonal array composite structure fluorescent ceramic proposed by the present invention controls the Ce 3+ concentration gradient distribution and the laser energy distribution by adjusting the constant k to enable light to be efficiently absorbed and converted in the central region, reduce the energy loss in the edge region, and improve the light extraction efficiency. The Gaussian distribution enables the light intensity to smoothly transition from the center to the edge, reduces the sudden drop in brightness at the edge of the spot, and improves the luminescence uniformity. It helps to regulate the light field distribution, reduce scattering and stray light, and improve the collimation and directivity of the light beam. In addition, the central region with a high rare earth ion concentration absorbs more light energy and generates heat, and the Gaussian distribution helps the heat to diffuse from the center to the outside, reducing the risk of local overheating and extending the material life. The Gaussian gradient distribution can reduce the stress concentration inside the material and improve the mechanical strength and stability.

[0047] (4) The unique conical structure of the fluorescent ceramic in the fluorescent conical-embedded hexagonal array composite structure fluorescent ceramic proposed by the present invention can, on the one hand, effectively reduce the total internal reflection, enhance the light output, and thus improve the light extraction efficiency. On the other hand, the conical structure helps to control the beam divergence angle and improve the beam quality, which is suitable for laser illumination applications that require high collimation. In addition, the conical structure significantly increases the surface area of the fluorescent ceramic compared to the traditional structure, which is beneficial to heat dissipation, thereby reducing the temperature of the ceramic during operation, improving the thermal stability and life. Finally, the conical design helps to form a smooth transition at the interface, thereby reducing the interface stress generated by the sudden change in shape and improving the overall mechanical strength and stability.

[0048] (5) The fluorescent vertebral body embedded hexagonal array composite structure fluorescent ceramic proposed by the present invention constructs a heterogeneous interface at the microscopic scale by adopting a T-component main structure with a thermal expansion coefficient matching that of the fluorescent ceramic, significantly reducing the stress concentration problem inside the ceramic block induced by temperature changes, effectively preventing structural damage, and thus greatly improving the reliability, durability, and thermal fracture resistance of the ceramic block during the thermal cycling process. In addition, the fluorescent vertebral body embedded hexagonal array composite structure fluorescent ceramic proposed by the present invention realizes a significant improvement in the overall heat dissipation performance of the material by virtue of the microscopic and highly interconnected heat conduction channels inside the ceramic, and its thermal conductivity is as high as 20 - 200 Wm -1 K -1 , which is much higher than the thermal conductivity of traditional fluorescent ceramics, providing a solid thermal management foundation for the application of fluorescent ceramics under high power density and high heat load conditions.

[0049] (6) The fluorescent vertebral body embedded hexagonal array composite structure fluorescent ceramic proposed by the present invention significantly improves the hardness and impact resistance of the ceramic block by coating a ceramic matrix with the composition of T on the fluorescent ceramic. The Vickers hardness of the composite structure ceramic is as high as 1200 - 2000 HV, and the fracture toughness is as high as 1.5 - 3.5 MPa m 1 / 2 , which is much higher than that of traditional single ceramics.

[0050] (7) The present invention provides a preparation method for an array honeycomb conical composite structure fluorescent ceramic prepared by photocuring 3D printing. By changing the 3D printing parameters, the size and quantity of the conical fluorescence can be changed to achieve a balance between the light emission performance and heat dissipation level of the device. In addition, the thickness of the fluorescent ceramic prepared by this method is controllable, the process is simple, and it is applicable to large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 is a schematic diagram of a single unit of the fluorescent vertebral body embedded hexagonal array composite structure fluorescent ceramic of the present invention.

[0052] Figure 2 is a schematic diagram of the fluorescent vertebral body embedded hexagonal array composite structure fluorescent ceramic of the present invention.

[0053] Figure 3 is the electroluminescence spectrum of the fluorescent vertebral body embedded hexagonal array composite structure fluorescent ceramic of the present invention.

[0054] Figure 4 is the two-dimensional and three-dimensional diagram of the light-emitting spot of the fluorescent vertebral body embedded hexagonal array composite structure fluorescent ceramic of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0055] The technical solutions of the present invention will be further described in detail below in conjunction with specific embodiments. In the following embodiments, Ce 3+oxide powder CeO 2 The mass percentage purity of the raw material is ≥99.9%; Y 2 O 3 The mass percentage purity of the raw material is ≥99.9%; Gd 2 O 3 The mass percentage purity of the raw material is ≥99.9%; alumina powder Al 2 O 3 The mass percentage purity of the raw material is ≥99.9%. The particle size range of T is 10 - 50 μm, and the particle size range of each component in L is 100 - 200 nm.

[0056] Example 1

[0057] As Figure 2 shown, a preparation method of a fluorescent cone - embedded hexagonal array composite - structure fluorescent ceramic is as follows:

[0058] (1) Prepare a hexagonal ceramic matrix green body by using a photocuring 3D printing technology combined with a gel technology: Print a gel - state slurry of composition T into a plurality of orderly - arranged hexagonal ceramic matrices with conical grooves. The specific steps are as follows:

[0059] ① Pre - dry the powder T, and then place the powder T, absolute ethanol, and surfactant ammonium oxide together in a ball - milling tank. Ball - mill for 3.5 h at a rotation speed of 180 r / min to prepare a suspension. The powder T is at least one of ZnO, Al 2 O 3 and AlN. The grinding balls are high - purity alumina balls with an average particle size of 10 μm. The mass of absolute ethanol is 2 times the mass of the powder T, and the mass of the surfactant ammonium oxide is 1 / 80 of the mass of the powder T. Use a rotary evaporator to remove the absolute ethanol in the suspension at a heating temperature of 60 °C, and then place it in an oven for heat treatment at 90 °C for 7 h. After cooling to room temperature, grind the obtained powder and pass through a 150 - mesh sieve to obtain the modified powder T;

[0060] ② Mix pentaerythritol tetraacrylate, 1,6 - hexanediol diacrylate, polyurethane acrylate, n - octanol, and polyethylene glycol to obtain a photocuring material, where pentaerythritol tetraacrylate:1,6 - hexanediol diacrylate:polyurethane acrylate:n - octanol:polyethylene glycol = 4:5:4:4:3. Add the photocuring material to deionized water to prepare a premix. Then add the modified powder T in step ① and a dispersant BYK 9077 accounting for 3 wt% of the mass of the modified powder T to the premix, and ball - mill for 13 h at a rotation speed of 280 r / min to prepare a ceramic matrix slurry with a solid content of 48 vol%;

[0061] ③ Add 1 wt% photoinitiator Irgacure 819 based on the total mass of the ceramic matrix slurry. After ball milling for 15 min under the condition of a rotation speed of 280 - 330 r / min, place it in the material tank of the DLP 3D printer.

[0062] ④ Set the layer thickness of the printing parameters to 20 μm, the exposure energy density to 31.5 mj / cm 2 , and the single - layer curing time to 5 s. As Figure 1 shown, use 3D modeling software to establish a 3D model of the hexagonal ceramic matrix, import it into the printer through CeraRay software, and prepare a hexagonal ceramic matrix blank by layer - by - layer cumulative printing. During the printing process, perform UV irradiation photocuring throughout to obtain a hexagonal ceramic matrix with conical grooves.

[0063] (2) Introduce a fluorescent ceramic slurry with the composition of L into the conical grooves of the ceramic matrix obtained in (1). After gel curing, construct a fluorescent vertebral body embedded hexagonal array composite - structure fluorescent ceramic. The method is as follows:

[0064] ① Mix CeO 2 , Y 2 O 3 , Gd 2 O 3 and Al 2 O 3 according to the chemical formula [(Y 0.99 Gd 0.01 ) 0.999 Ce 0.001 3 Al 5 O 12 to obtain an oxide mixed powder. After ball milling, drying, grinding, and sieving, obtain a fluorescent ceramic powder GdYAG:Ce, defined as powder L.

[0065] ② Prepare a premixed solution by adding 1.0 wt% pH regulator tetramethylammonium hydroxide and 0.5 wt% dispersant ammonium citrate in deionized water. Add the pre - dried fluorescent ceramic powder, i.e., powder L, to the premixed solution in 4 portions, and perform low - speed ball milling using an alumina ball milling tank. The ball milling speed is 50 r / min, the grinding balls are high - purity alumina balls, and the mass ratio of powder L to the grinding balls is 1:3. After all the ceramic powder is added to the premixed solution, ball mill for 12 h to obtain a ceramic slurry. Among them, when adding powder L to the premixed solution in 4 portions for ball milling, the first addition amount is 25% of the mass of powder L, the second - third addition amounts are 45% of the mass of powder L, and the fourth addition amount is 30% of the mass of powder L.

[0066] ​③ Add monomer acrylamide AM and crosslinking agent N,N'-methylenebisacrylamide to the ceramic slurry obtained in ②. Among them, the total mass of AM and N,N'-methylenebisacrylamide accounts for 0.8 wt% of the ceramic slurry, and the mass ratio of AM to N,N'-methylenebisacrylamide is 1 / 10. Continue ball milling for 3 h, and perform defoaming treatment on the ball-milled slurry to obtain ceramic slurries with different concentrations and a solid content of 50 vol%;

[0067] ④ Add photoinitiator Irgacure 819, which accounts for 0.4 wt% of the total mass of the ceramic slurry, to the fluorescent ceramic slurry obtained in ③, and ball mill for 8 min under the condition of a rotation speed of 350 r / min to obtain a fluorescent ceramic slurry, defined as slurry A, and place it in the material tank A of the DLP 3D printer;

[0068] ⑤ Prepare the ceramic powder GdYAG without Ce according to steps ① - ④, obtain the GdYAG ceramic slurry defined as slurry B, and then place it in the material tank B of the DLP 3D printer; 3+

[0069] ⑥ Use 3D modeling software to establish a model of an array of conical fluorescent ceramics, define the gradient distribution of the Ce concentration in the model. Specifically, it means that the Ce concentration gradually increases from the bottom of the cone to the top of the cone. Slice the 3D model into 100 layers, and assign a slurry to each layer; Subsequently, convey slurry A in the material tank A and slurry B in the material tank B to the microfluidic mixer. The microfluidic mixer dynamically adjusts the flow rate ratio between slurry A and slurry B according to a preset curve, outputs a mixed slurry with the target concentration, and finally the mixed slurry is conveyed to the print head, printed layer by layer on the ceramic substrate, and cured layer by layer to obtain a fluorescent conical body embedded hexagonal array composite structure fluorescent ceramic green body; The thickness of the slice is 20 μm; In the 3D printing parameters, the layer thickness is the thickness of the slice, the exposure energy density is 31.5 mj / cm, and the single-layer curing time is 5 s. Among them, the concentration of slurry A is 100% C, the concentration of slurry B is 0% C, the concentration at the top of the cone is 100% C, and it gradually decreases layer by layer with a concentration gradient of 1% C. By controlling the volume flow rate ratio between slurry A and slurry B, a mixed slurry with the target concentration is output. For example, 50% C is formed by mixing slurry A and slurry B evenly at a volume ratio of 1:1. 3+ 3+ 2 o o o o o

[0070] ​​​​​​​​​(3)Embed the fluorescent cones into the hexagonal array composite structure fluorescent ceramic green body and place it in an alumina crucible. Heat it to 360 °C at a heating rate of 0.5 °C / min and hold for 15 h, then heat it to 800 °C at a heating rate of 1.5 °C / min and hold for 8 h. Sinter the green body in a muffle furnace to remove the organic matter in the green body. Subsequently, heat the sintered composite structure fluorescent ceramic green body to 1550 °C at a heating rate of 0.5 °C / min in an argon atmosphere and hold for 12 h. After the holding is completed, cool it to room temperature at a cooling rate of 0.5 °C / min to obtain the fluorescent cone-embedded hexagonal array composite structure fluorescent ceramic. Among them, 127 conical fluorescent ceramics are designed, the ceramic matrix accounts for 55% of the cross-section of the whole material, the bottom diameter of a single conical fluorescent ceramic is 30 μm, and the thickness, length and width of the whole ceramic are 2.0 mm, 1.0 mm and 0.8 mm respectively.

[0071] The thermal conductivity of the fluorescent cone-embedded hexagonal array composite structure fluorescent ceramic prepared in this example is 25 Wm - 1 K -1 , the Vickers hardness is 1200 HV, and the fracture toughness is as high as 1.5 MPa m 1 / 2 .

[0072] As Figure 3 shown, use a blue laser with an emission peak of 450 nm and a spot diameter of 200 μm as the excitation source, and its power density is 10.19 W / mm 2 . Package it with the fluorescent ceramic prepared in this example. As Figure 4 shown, when the proportionality constant k between the laser energy distribution and the Ce 3+ concentration distribution is 1, the beam expansion rate of the light-emitting spot of the fluorescent cone-embedded hexagonal array composite structure fluorescent ceramic is 18%, the beam expansion value is 36 μm, and the luminous efficiency is 321 lm / W; when the proportionality constant k between the laser energy distribution and the Ce 3+ concentration distribution is < 1, the beam expansion rate of the light-emitting spot of the fluorescent cone-embedded hexagonal array composite structure fluorescent ceramic is 15%, the beam expansion value is 30 μm, and the luminous efficiency is 273 lm / W; when the proportionality constant k between the laser energy distribution and the Ce 3+ concentration distribution is > 1, the beam expansion rate of the light-emitting spot of the fluorescent cone-embedded hexagonal array composite structure fluorescent ceramic is 32%, the beam expansion value is 64 μm, and the luminous efficiency is 257 lm / W.

[0073] Example 2

[0074] As Figure 2 shown, a preparation method of an array honeycomb conical composite structure fluorescent ceramic, the specific steps are:

[0075] (1) Prepare a green body of a hexagonal ceramic matrix by using stereolithography 3D printing technology combined with gel technology: Print a gel-state slurry with the composition of T into a hexagonal ceramic matrix with a plurality of orderly arranged conical grooves. The specific steps are as follows:

[0076] ① Pre-dry the powder T, and then place the powder T, absolute ethanol, and surfactant ammonium oxide together in a ball mill jar. Ball mill for 1.5 h at a rotation speed of 260 r / min to prepare a suspension. The powder T is at least one of ZnO, Al 2 O 3 and AlN. The grinding balls are high-purity alumina balls with an average particle size of 50 μm. The mass of absolute ethanol is 4 times that of the powder T, and the mass of the surfactant ammonium oxide is 1 / 120 of the mass of the powder T. Use a rotary evaporator to remove the absolute ethanol in the suspension at a heating temperature of 80 °C, and then place it in an oven and heat-treat at 110 °C for 7 h. After cooling to room temperature, grind the obtained powder and pass through a 200-mesh sieve to obtain the modified powder T;

[0077] ② Mix pentaerythritol tetraacrylate, 1,6-hexanediol diacrylate, polyurethane acrylate, n-octanol, and polyethylene glycol to obtain a photocurable material. Among them, pentaerythritol tetraacrylate: 1,6-hexanediol diacrylate: polyurethane acrylate: n-octanol: polyethylene glycol = 20%: 25%: 20%: 20%: 15%. Add the photocurable material to deionized water to prepare a premixed solution. Then add the modified powder T in step ① and a dispersant BYK9077 accounting for 3 wt% of the mass of the modified powder T to the premixed solution, and ball mill for 9 h at a rotation speed of 330 r / min to prepare a ceramic matrix slurry with a solid content of 52 vol%;

[0078] ③ Add a photoinitiator Irgacure 819 accounting for 2 wt% of the total mass of the slurry to the ceramic matrix slurry. After ball milling for 12 min at a rotation speed of 330 r / min, place it in the material tank of a DLP 3D printer;

[0079] ④ Set the layer thickness of the printing parameters to 20 μm, the exposure energy density to 31.5 mj / cm 2 , and the single-layer curing time to 5 s. Use 3D modeling software to establish a three-dimensional model of the hexagonal ceramic matrix, import it into the printer through CeraRay software, and prepare a ceramic matrix green body by layer-by-layer cumulative printing. During the printing process, UV irradiation photocuring is carried out throughout, and finally a hexagonal ceramic matrix with conical grooves is obtained.

[0080] (2) Introduce a fluorescent ceramic slurry with the composition of L into the conical grooves of the ceramic matrix obtained in (1). After gel curing, construct a fluorescent vertebral body embedded in a hexagonal array composite structure fluorescent ceramic. The method is as follows:

[0081] ① Mix CeO 2 , Y 2 O 3 , Gd 2 O 3 and Al 2 O 3 according to the stoichiometric formula [(Y 0.99 Gd 0.01 ) 0.995 Ce 0.05 3 Al 5 O 12 to obtain a mixed oxide powder. After ball milling, drying, grinding and sieving, the fluorescent ceramic powder GdYAG:Ce is obtained, which is defined as powder L;

[0082] ② Add 1.0 wt% pH regulator tetramethylammonium hydroxide and 0.5 wt% dispersant ammonium citrate to deionized water to prepare a premixed solution. Add the pre-dried fluorescent ceramic powder to the premixed solution in 4 portions and perform low-speed ball milling using an alumina ball milling tank. The ball milling speed is 50 r / min, the grinding balls are high-purity alumina balls, and the mass ratio of powder L to the grinding balls is 1:3. After all the ceramic powder is added to the premixed solution, ball mill for 12 h to obtain a ceramic slurry. Among them, when adding powder L to the premixed solution in 4 portions for ball milling, the first addition amount is 25% of the mass of powder L, the second to third addition amounts are 45% of the mass of powder L, and the fourth addition amount is 30% of the mass of powder L;

[0083] ③ Add a total of 0.8 wt% monomer acrylamide AM and crosslinking agent N,N'-methylenebisacrylamide to the ceramic slurry obtained in ②. The mass ratio of AM to N,N'-methylenebisacrylamide is 1 / 10, continue ball milling for 3 h, and perform degassing treatment on the ball-milled slurry to obtain a ceramic slurry with a solid content of 55 vol%;

[0084] ④ Add 0.4 wt% photoinitiator Irgacure 819 based on the total mass of the ceramic slurry to the ceramic slurry obtained in ③, and ball mill for 8 min under the condition of a rotation speed of 350 r / min to obtain a fluorescent ceramic slurry, which is defined as slurry A and placed in the trough A of a DLP 3D printer;

[0085] ⑤ Prepare a Ce 3+ -free ceramic powder GdYAG according to steps ①-④ to obtain a GdYAG ceramic slurry defined as slurry B, and then place it in the trough B of a DLP 3D printer;

[0086] ⑥ Use 3D modeling software to establish a model of an array of conical fluorescent ceramics, and define the gradient distribution of the Ce 3+ concentration in the model. Specifically, it refers to the Ce 3+ ​The concentration gradually increases. The 3D model is sliced into 150 layers, and a slurry is specified for each layer. Subsequently, slurry A in trough A and slurry B in trough B are transported to a microfluidic mixer. The microfluidic mixer dynamically adjusts the flow rate ratio between slurry A and slurry B according to a preset curve, outputs a mixed slurry with a target concentration. Finally, the mixed slurry is transported to a print head, printed layer by layer on a ceramic substrate, and cured layer by layer to obtain a fluorescent cone-embedded hexagonal array composite structure fluorescent ceramic green body. The thickness of the slice is 10 μm. The layer thickness in the 3D printing parameters is the thickness of the slice, and the exposure energy density is 31.5 mj / cm 2 and the single-layer curing time is 4 s. Among them, the concentration of slurry A is 100% C o , and the concentration of slurry B is 0% C o , and the concentration at the top of the cone is 100% C o , and decreases layer by layer with a concentration gradient of 0.666% C o . By controlling the volume flow rate ratio between slurry A and slurry B, a mixed slurry with a target concentration is output.

[0087] (3) Place the composite structure fluorescent ceramic green body in an alumina crucible, heat it to 380 °C at a heating rate of 1 °C / min and hold for 13 h, then heat it to 800 °C at a heating rate of 2 °C / min and hold for 8 h, and perform biscuit firing in a muffle furnace to remove the organic matter in the green body. Heat the biscuit-fired composite structure fluorescent ceramic green body to 1650 °C at a heating rate of 1 °C / min in an argon atmosphere and hold for 10 h. After the holding is completed, cool it to room temperature at a cooling rate of 1.0 °C / min to obtain a fluorescent cone-embedded hexagonal array composite structure fluorescent ceramic. Among them, 10 designed conical fluorescent ceramics are provided. The hexagonal ceramic substrate accounts for 40% of the cross-section of the entire material. The bottom diameter of a single conical fluorescent ceramic is 150 μm, and the thickness, length, and width of the overall ceramic are 1.5 mm, 1.5 mm, and 1.0 mm respectively.

[0088] The thermal conductivity of the fluorescent cone-embedded hexagonal array composite structure fluorescent ceramic prepared in this example is 200 Wm -1 K -1 , the Vickers hardness is 2000 HV, and the fracture toughness is as high as 3.5 MPa m 1 / 2 .

[0089] Use a blue laser with an emission peak of 450 nm and a spot diameter of 200 μm as the excitation source, and its power density is 10.19 W / mm 2 , encapsulate it with the fluorescent ceramic prepared in this example. When the laser energy distribution is the same as that of Ce 3+When the proportionality constant k of the concentration distribution is 1, the beam expansion rate of the light-emitting spot of the fluorescent cone embedded in the hexagonal array composite structure fluorescent ceramic is 40%, the beam expansion value is 80 μm, and the luminous efficiency is 284 lm / W; when the laser energy distribution and Ce 3+ When the proportionality constant k of the concentration distribution is < 1, the beam expansion rate of the light-emitting spot of the fluorescent cone embedded in the hexagonal array composite structure fluorescent ceramic is 29%, the beam expansion value is 58 μm, and the luminous efficiency is 242 lm / W; when the laser energy distribution and Ce 3+ When the proportionality constant k of the concentration distribution is > 1, the beam expansion rate of the light-emitting spot of the fluorescent cone embedded in the hexagonal array composite structure fluorescent ceramic is 64%, the beam expansion value is 128 μm, and the luminous efficiency is 228 lm / W.

[0090] Example 3

[0091] As Figure 2 shown, a preparation method of an array honeycomb conical composite structure fluorescent ceramic, the specific steps are as follows:

[0092] (1) Prepare a hexagonal ceramic matrix green body by using a photocuring 3D printing technology combined with a gel technology: print a gel-state slurry with the composition of T into a hexagonal ceramic matrix with a plurality of orderly arranged conical grooves, and the specific steps are as follows:

[0093] ① Pre-dry the powder T, and then place the powder T, anhydrous ethanol and the surfactant ammonium oxide together in a ball mill jar, and ball mill for 2 h at a rotation speed of 200 r / min to prepare a suspension. The powder T is at least one of ZnO, Al 2 O 3 and AlN, the grinding balls are high-purity alumina balls with an average particle size of 30 μm, the mass of anhydrous ethanol is 3 times the mass of the powder T, and the mass of the surfactant ammonium oxide is 1 / 100 of the mass of the powder T; use a rotary evaporator to remove the anhydrous ethanol in the suspension at a heating temperature of 70 °C, and then place it in an oven and heat-treat at 100 °C for 5 h; after cooling to room temperature, grind the obtained powder and pass through a 1200-mesh sieve to obtain the modified powder T;

[0094] ② Mix pentaerythritol tetraacrylate, 1,6-hexanediol diacrylate, polyurethane acrylate, n-octanol, and polyethylene glycol to obtain a photocuring material, wherein, pentaerythritol tetraacrylate: 1,6-hexanediol diacrylate: polyurethane acrylate: n-octanol: polyethylene glycol = 20%: 25%: 20%: 20%: 15%. Add the photocuring material into deionized water to prepare a premixed solution, and then add the modified powder T in step ① and a dispersant BYK9077 accounting for 3 wt% of the mass of the modified powder T into the premixed solution, and ball mill for 11 h at a rotation speed of 280 - 330 r / min to prepare a ceramic matrix slurry with a solid content of 50 vol%;

[0095] ③ Add photoinitiator Irgacure 819 accounting for 1.5 wt% of the total mass of the ceramic matrix slurry. After ball milling for 13 min under the condition of a rotation speed of 300 r / min, place it in the material tank of a DLP 3D printer;

[0096] ④ Set the layer thickness of the printing parameters to 20 μm, the exposure energy density to 31.5 mj / cm 2 , the single-layer curing time to 5 s. Use 3D modeling software to establish a 3D model of the hexagonal ceramic matrix, import it into the printer through CeraRay software, and prepare a hexagonal ceramic matrix blank by layer-by-layer cumulative printing. During the printing process, perform UV irradiation photocuring throughout, and finally obtain a hexagonal ceramic matrix with a conical groove.

[0097] (2) Introduce a fluorescent ceramic slurry with the composition of L into the conical groove of the ceramic matrix obtained in (1). After gel curing, construct a fluorescent vertebral body embedded hexagonal array composite structure fluorescent ceramic; the method is as follows:

[0098] ① Mix CeO 2 , Y 2 O 3 , Gd 2 O 3 and Al 2 O 3 according to the chemical formula [(Y 0.99 Gd 0.01 ) 0.997 Ce 0.003 3 Al 5 O 12 to obtain an oxide mixed powder. After ball milling, drying, grinding and sieving, obtain a fluorescent ceramic powder GdYAG:Ce, defined as powder L;

[0099] ② Add 1.0 wt% pH regulator tetramethylammonium hydroxide and 0.5 wt% dispersant ammonium citrate to deionized water to prepare a premixed solution. Add the pre-dried fluorescent ceramic powder to the premixed solution in 4 portions, and perform low-speed ball milling using an alumina ball milling tank. The ball milling speed is 50 r / min, and the grinding balls are high-purity alumina balls. The mass ratio of powder L to the grinding balls is 1:3; after all the ceramic powder is added to the premixed solution, ball mill for 12 h to obtain a ceramic slurry; among them, add powder L to the premixed solution in 4 portions for ball milling. The addition amount for the first time is 25% of the mass of powder L, the addition amounts for the second to third times are 45% of the mass of powder L, and the addition amount for the fourth time is 30% of the mass of powder L; the concentration of the fluorescent ceramic slurry A is 100% C o , and the concentration of the slurry B is 0% C o .

[0100] ​③ Add monomer acrylamide AM and crosslinking agent N,N'-methylenebisacrylamide with a total proportion of 0.8 wt% to the ceramic slurry obtained in ②. The mass ratio of AM to N,N'-methylenebisacrylamide is 1 / 10. Continue ball milling for 3 h, and defoam the ball-milled slurry to obtain a ceramic slurry with a solid content of 52 vol%.

[0101] ④ Add photoinitiator Irgacure 819, which accounts for 0.4 wt% of the total mass of the ceramic slurry, to the ceramic slurry obtained in ③. Ball mill for 8 min under the condition of a rotation speed of 350 r / min, define it as slurry A, and place it in the material tank A of the DLP 3D printer.

[0102] ⑤ Prepare the Ce-free 3+ ceramic powder GdYAG according to steps ① - ④, obtain the GdYAG ceramic slurry defined as slurry B, and then place it in the material tank B of the DLP 3D printer.

[0103] ⑥ Use 3D modeling software to establish a model of the array conical fluorescent ceramic, and define the gradient distribution of the Ce 3+ concentration in the model. Specifically, it means that the Ce 3+ concentration gradually increases from the bottom of the cone to the top of the cone. Slice the 3D model into 100 layers, and assign a slurry to each layer; Subsequently, convey slurry A in the material tank A and slurry B in the material tank B to the microfluidic mixer. The microfluidic mixer dynamically adjusts the flow ratio between slurry A and slurry B according to the preset curve, outputs the mixed slurry with the target concentration, and finally the mixed slurry is conveyed to the print head, printed layer by layer on the ceramic substrate, and cured layer by layer to obtain a fluorescent cone-embedded hexagonal array composite structure fluorescent ceramic green body; the thickness of the slice is 10 μm; the layer thickness in the 3D printing parameters is the thickness of the slice, the exposure energy density is 31.5 mj / cm 2 and the single-layer curing time is 2 s. Among them, the concentration of slurry A is 100% C o and the concentration of slurry B is 0% C o and the concentration at the top of the cone is 100% C o and decreases layer by layer with a concentration gradient of 1% C o By controlling the volume flow ratio between slurry A and slurry B, the mixed slurry with the target concentration is output.

[0104] (3) Place the composite - structured fluorescent ceramic green body in an alumina crucible, heat it at a heating rate of 0.8 °C / min to 370 °C and hold for 14 h, then heat it at a heating rate of 2 °C / min to 750 °C and hold for 9 h, and perform biscuit firing in a muffle furnace to remove the organic matter in the green body. Subsequently, heat the biscuit - fired composite - structured fluorescent ceramic green body in a nitrogen atmosphere at a heating rate of 0.8 °C / min to 1600 °C and hold for 11 h. After the holding is completed, cool it to room temperature at a cooling rate of 0.8 °C / min to obtain the fluorescent cone - embedded hexagonal array composite - structured fluorescent ceramic. Among them, 18 designed conical fluorescent ceramics are used, the hexagonal ceramic matrix accounts for 50% of the cross - section of the whole material, the bottom diameter of a single conical fluorescent ceramic is 30 μm, and the thickness, length, and width of the whole ceramic are 1.0 mm, 1.3 mm, and 0.9 mm, respectively.

[0105] The thermal conductivity of the fluorescent cone - embedded hexagonal array composite - structured fluorescent ceramic prepared in this example is 60 Wm - 1 K -1 , the Vickers hardness is 1600 HV, and the fracture toughness is as high as 2.5 MPa m 1 / 2 .

[0106] Use a blue laser with an emission peak of 450 nm and a spot diameter of 200 μm as the excitation source, and its power density is 10.19 W / mm 2 , encapsulate it with the fluorescent ceramic prepared in this example. When the proportionality constant k between the laser energy distribution and the Ce 3+ concentration distribution is 1, the beam expansion rate of the light - emitting spot of the fluorescent cone - embedded hexagonal array composite - structured fluorescent ceramic is 30%, the beam expansion value is 60 μm, and the luminous efficiency is 298 lm / W. When the proportionality constant k between the laser energy distribution and the Ce 3+ concentration distribution is < 1, the beam expansion rate of the light - emitting spot of the fluorescent cone - embedded hexagonal array composite - structured fluorescent ceramic is 24%, the beam expansion value is 48 μm, and the luminous efficiency is 254 lm / W; when the proportionality constant k between the laser energy distribution and the Ce 3+ concentration distribution is > 1, the beam expansion rate of the light - emitting spot of the fluorescent cone - embedded hexagonal array composite - structured fluorescent ceramic is 46%, the beam expansion value is 92 μm, and the luminous efficiency is 239 lm / W.

[0107] The present invention effectively solves the problem of light - spot expansion of the fluorescent ceramic by precisely regulating the matching relationship between the cone bottom size and the incident laser spot, and utilizing the synergistic effect generated by the optical property difference between the hexagonal ceramic matrix and the fluorescent ceramic. Further, by optimizing the Ce in the fluorescent ceramic 3+The geometric matching relationship between the concentration gradient distribution and the laser energy distribution, combined with the total internal reflection suppression characteristics of the conical structure, significantly improves the light extraction efficiency and luminescence uniformity of the ceramic. The proposed composite structure of fluorescent cones embedded in a hexagonal array can achieve highly collimated, efficient, and high-brightness luminescence. After encapsulating this fluorescent ceramic with a laser excitation source, it can be widely applied to the fields of laser lighting and display.

[0108] The above shows and describes the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and the descriptions in the specification only illustrate the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. A fluorescent ceramic with a composite structure of fluorescent cones embedded in a hexagonal array, characterized in that: The composite structure fluorescent ceramic comprises an array-arranged hexagonal prism ceramic matrix, in which orderly arranged conical fluorescent ceramics are oriented and constructed, the ceramic matrix has a composition of T, and the fluorescent ceramic has a composition of L, wherein T is one of ZnO, Al2O3 and AlN; L is [(Y 0.99 G 0.01 ) 1-x Ce x ]3Al5O 12 , 0.001≤x≤0.05, Ce in cone fluorescent ceramics 3+ The concentration gradient distribution refers to the concentration gradient distribution from the bottom of the cone to the top of the cone. 3+ The concentration gradually increases.

2. The fluorescent cone embedded hexagonal array composite structure fluorescent ceramic according to claim 1, characterized in that: The cross-sectional area of ​​the ceramic matrix accounts for 40%-55% of the entire ceramic cross-sectional area, the diameter of the cone bottom of the conical fluorescent ceramic is 60μm-300μm, and the overall thickness, length and width of the composite structure fluorescent ceramic are 1mm-2mm, 1.0mm-1.5mm, and 0.8mm-1.0mm respectively.

3. The fluorescent cone embedded hexagonal array composite structure fluorescent ceramic according to claim 1, characterized in that: Ce in Conical Fluorescent Ceramics 3+ The concentration is distributed in a gradient and satisfies the geometric relationship (I) and (II) with the laser Gaussian energy distribution: Where C(r) is the Ce at a distance r from the center 3+ concentration, C0 is the central concentration, σ c is the standard deviation of the concentration distribution; Where I(r) is the laser intensity at a distance r from the center, I0 is the center intensity, and σ l is the standard deviation of the laser beam; In order to make Ce 3+ The concentration distribution matches the laser energy distribution and adjusts the standard deviation σ of the concentration distribution c The standard deviation of the laser beam σ l The relationship between them satisfies σ c = kσ l , where k = 1, the light conversion efficiency is the highest; when k < 1, Ce 3+ The concentration distribution is more concentrated, which is suitable for scenes with high local light intensity. When k>1, Ce 3+ The concentration distribution is wider, suitable for uniform light output scenarios.

4. The method for preparing the fluorescent ceramic with a composite structure of fluorescent cones embedded in a hexagonal array according to any one of claims 1 to 3, characterized in that: The gel technology combined with the light-curing 3D printing technology is used to construct orderly arranged cone fluorescent ceramic units in the arrayed hexagonal ceramic matrix, and finally form a fluorescent cone embedded in the hexagonal array composite structure fluorescent ceramic, which specifically includes the following steps: (1) A ceramic blank is prepared by using a light-curing 3D printing technology combined with a gel technology: a gel slurry with a component T is printed into a hexagonal prism ceramic matrix with an array arrangement of conical grooves, and a fluorescent ceramic slurry with a component L is introduced into the conical grooves to construct a fluorescent ceramic blank with a composite structure of fluorescent cones embedded in a hexagonal array; (2) The fluorescent cone is embedded in the hexagonal array composite structure fluorescent ceramic blank, and then the blank is fired at high temperature to obtain the fluorescent cone embedded in the hexagonal array composite structure fluorescent ceramic.

5. The method for preparing fluorescent ceramics with a composite structure of fluorescent cones embedded in hexagonal arrays according to claim 4, characterized in that: The method of printing the gel slurry having the component T into a hexagonal ceramic matrix having an array arrangement of conical grooves in step (1) is as follows: ① Pre-dry the powder T, then place the powder T, anhydrous ethanol and surfactant ammonium oxide in a ball mill, and prepare a suspension by ball milling for 1.5-3.5 hours at a rotation speed of 180-260r / min, wherein the powder T is at least one of ZnO, Al2O3 and AlN, the particle size of the powder T is in the range of 10-50μm, the grinding ball is a high-purity alumina ball with an average particle size of 10-50μm, the mass of anhydrous ethanol is 2-4 times the mass of the powder T, and the mass of surfactant ammonium oxide is 1 / 80-1 / 120 of the mass of the powder T; use a rotary evaporator at a heating temperature of 60-80°C to remove the anhydrous ethanol in the suspension, then place it in an oven and heat treat it at 90°C-110°C for 4h-7h; after cooling to room temperature, grind the obtained powder and pass it through a 150-200 mesh sieve to obtain the modified powder T; ② Pentaerythritol tetraacrylate, 1-6-hexanediol diacrylate, polyurethane acrylate, n-octanol, and polyethylene glycol are mixed to obtain a photocurable material, wherein pentaerythritol tetraacrylate: 1-6-hexanediol diacrylate: polyurethane acrylate: n-octanol: polyethylene glycol = 20%: 25%: 20%: 20%: 15%; the photocurable material is added to deionized water to prepare a premix, and then the modified powder T in step ① and the dispersant BYK 9077 accounting for 3wt% of the mass of the powder T are added to the premix, and ball milled at a rotation speed of 280-330r / min for 9-13h to prepare a ceramic matrix slurry with a solid content of 48vol%-52vol%; ③ Add 1-2wt% of the photoinitiator Irgacure 819 to the ceramic matrix slurry, ball mill for 12-15min at a speed of 280-330r / min, and place it in the material tank of the DLP 3D printer; ④ Set the printing parameters to a layer thickness of 20 μm and an exposure energy density of 31.5 mj / cm 2 , the single-layer curing time is 5s, and the 3D model of the hexagonal ceramic matrix is ​​established by using the 3D modeling software. It is imported into the printer through the CeraRay software, and a hexagonal ceramic body with an array arrangement of conical grooves is prepared by cumulative printing layer by layer. UV irradiation photocuring is carried out throughout the printing process to finally obtain the hexagonal ceramic matrix.

6. The method for preparing fluorescent ceramics with a composite structure of fluorescent cones embedded in hexagonal arrays according to claim 4, characterized in that: The method of introducing a fluorescent ceramic slurry having a component L into the conical groove of the hexagonal ceramic matrix to construct a fluorescent ceramic blank with a composite structure of a fluorescent cone embedded in a hexagonal array is as follows: ① CeO2, Y2O3, Gd2O3 and Al2O3 are mixed according to the stoichiometric formula [(Y 0.99 G 0.01 ) 1-x Ce x ]3Al5O 12 , 0.001≤x≤0.05 are mixed to obtain oxide mixed powder, and after ball milling, drying, grinding and sieving, fluorescent ceramic powder GdYAG:Ce is obtained; wherein the particle size range of CeO2, Y2O3, Gd2O3 and Al2O3 is 100-200nm; ② Add 1.0wt% of pH regulator tetramethylammonium hydroxide and 0.5wt% of dispersant ammonium citrate to deionized water to prepare a premixed solution, add the fluorescent ceramic powder to the premixed solution in 4 times, and use an alumina ball mill to perform low-speed ball milling. The ball milling speed is 50r / min, the grinding balls are high-purity alumina balls, and the mass ratio of the fluorescent ceramic powder to the grinding balls is 1:3; after all the fluorescent ceramic powder is added to the premixed solution, the slurry is obtained by ball milling for 12 hours; wherein, the fluorescent ceramic powder is added to the premixed solution for ball milling in 4 times, the first addition amount is 25% of the mass of the fluorescent ceramic powder, the second-third addition amount is 45% of the mass of the fluorescent ceramic powder, and the fourth addition amount is 30% of the mass of the fluorescent ceramic powder; ③ Add 0.8 wt% of monomer acrylamide AM and crosslinking agent N,N'-methylenebisacrylamide to the slurry obtained in ②, the mass ratio of AM to N,N'-methylenebisacrylamide is 1 / 10, continue ball milling for 3 hours, and defoam the slurry after ball milling to obtain a ceramic slurry with a solid content of 50 vol%-55 vol%; ④ Add 0.4 wt% of the photoinitiator Irgacure 819 to the ceramic slurry obtained in ③, and ball mill for 8 min at a rotation speed of 350 r / min to obtain a fluorescent ceramic slurry defined as slurry A, which is placed in the material tank A of the DLP 3D printer; ⑤ Follow steps ①-④ to prepare Ce-free 3+ The ceramic powder GdYAG is obtained to obtain a GdYAG ceramic slurry defined as slurry B, which is placed in a material tank B of a DLP 3D printer; ⑥ Use 3D modeling software to build a model of the array conical fluorescent ceramics and define Ce in the model 3+ The concentration gradient distribution, specifically from the bottom of the cone to the top of the cone Ce 3+ The concentration gradually increases, the 3D model is sliced ​​into n layers, and a slurry is specified for each layer; then, slurry A in tank A and slurry B in tank B are delivered to the microfluidic mixer, and the microfluidic mixer dynamically adjusts the volume flow ratio between slurry A and slurry B according to the preset curve, outputs the mixed slurry of the target concentration, and finally the mixed slurry is delivered to the print head, where the concentration of slurry A is 100% C o , the concentration of slurry B is 0%C o , the concentration at the top of the cone is 100% C o ,by The fluorescent ceramic is printed layer by layer in the conical groove of the ceramic matrix in a manner of decreasing concentration gradient layer by layer, and solidified layer by layer to obtain a fluorescent cone embedded in a hexagonal array composite structure fluorescent ceramic blank; the thickness of the slice is 10-20 μm; the layer thickness in the 3D printing parameters is the thickness of the slice, and the exposure energy density is 31.5 mj / cm 2 , single layer curing time is 2-5s.

7. The method for preparing fluorescent ceramics with a composite structure of fluorescent cones embedded in hexagonal arrays according to claim 4, characterized in that: The specific operation of bisque firing in step (2) is as follows: embed the fluorescent cone into the hexagonal array composite structure fluorescent ceramic body and place it in an alumina crucible, heat it to 360-380°C at a heating rate of 0.5°C / min-1°C / min and keep it warm for 13h-15h, heat it to 700-800°C at a heating rate of 1.5°C / min-2°C / min and keep it warm for 8h-10h, and bisque fire it in a muffle furnace to remove organic matter in the bisque.

8. The method for preparing fluorescent ceramics with a composite structure of fluorescent cones embedded in hexagonal arrays according to claim 4, characterized in that: The specific operation of high temperature sintering in step (2) is as follows: the bisque-fired composite structure fluorescent ceramic blank is heated to 1550°C-1650°C in an argon / nitrogen atmosphere at a heating rate of 0.5°C / min-1°C / min and kept warm for 10-12h. After the heat preservation, the temperature is cooled to room temperature at a cooling rate of 0.5°C / min-1.0°C / min to obtain a composite structure fluorescent ceramic with fluorescent cones embedded in a hexagonal array.

9. The fluorescent cone embedded hexagonal array composite structure fluorescent ceramic according to any one of claims 1 to 3, characterized in that: Thermal conductivity is 20-200Wm -1 K -1 , Vickers hardness up to 1200-2000HV, fracture toughness up to 1.5-3.5MPa m 1 / 2 .

10. Application of the fluorescent ceramic with a composite structure of fluorescent cones embedded in hexagonal arrays according to any one of claims 1 to 3 in the field of laser lighting, characterized in that: Under the excitation of blue laser with emission peak of 450nm, the beam expansion rate of the luminous spot is 15%-64%, the beam expansion value is 30-128μm, and the luminous efficiency is 228-321lm / W.

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