Fluorescent ceramics and manufacturing method thereof, light-emitting device and projection device

Abstract

The present application relates to the technical field of fluorescent ceramics, and specifically discloses fluorescent ceramics and their manufacturing methods, light-emitting devices, and projection devices. The fluorescent ceramic includes a matrix, and at least luminescent centers, first scattering units, and second scattering units distributed within the matrix, where the refractive index of the first scattering units is greater than that of the luminescent centers, and the refractive index of the second scattering units is less than that of the luminescent centers. This configuration improves the scattering performance of the fluorescent ceramic with respect to fluorescence, thereby improving the light efficiency of the light source system.

Description

[Technical Field]

[0001] The present application relates to the field of fluorescent ceramics, and in particular to fluorescent ceramics and methods for manufacturing the same, light emitting devices and projection devices. [Background technology]

[0002] Unlike pure YAG ceramics, YAG fluorescent ceramics are made by doping YAG with lanthanide elements such as cerium, substituting trace amounts of the element for some of the yttrium sites, giving the YAG fluorescent ceramics luminescence properties and enabling it to convert incident light into light with a longer wavelength. Summary of the Invention [Problem to be solved by the invention]

[0003] The inventors of the present application have found, through a long period of research and development, that it is important to improve the luminous efficiency of fluorescent ceramics. Because of their structure, pure-phase ceramics in fluorescent ceramics have difficulty achieving high utilization rates for excitation light sources, and when fluorescent ceramics are excited, the number of luminescent centers is relatively small, resulting in low luminous efficiency.

[0004] Therefore, new fluorescent ceramics are needed to improve the luminous efficiency of current transparent fluorescent ceramics. [Means for solving the problem]

[0005] The present application provides a fluorescent ceramic, a manufacturing method thereof, a light emitting device, and a projection device, which can improve the scattering performance of the fluorescent ceramic with respect to fluorescence, thereby improving the light efficiency of a light source system.

[0006] According to one aspect, the present application provides a fluorescent ceramic, the fluorescent ceramic including at least a matrix, a luminescent center, a first scattering unit, and a second scattering unit distributed within the matrix, wherein the refractive index of the first scattering unit is greater than the refractive index of the luminescent center, and the refractive index of the second scattering unit is smaller than the refractive index of the luminescent center.

[0007] According to another aspect, the present application provides a method for manufacturing a fluorescent ceramic, the method comprising: preparing a matrix material, a scattering material, and phosphor particles of the fluorescent ceramic in a predetermined ratio, wherein the scattering material includes at least a pore-forming agent, first scattering particles, and second scattering particles; mixing the matrix material and the scattering material in a first solvent and ball milling the mixture to obtain a first ball-milled slurry; mixing the phosphor particles in a second solvent and ball milling the mixture to obtain a second ball-milled slurry; drying the first ball-milled slurry and the second ball-milled slurry, respectively; and then: crushing and sieving the powder to obtain a first powder and a second powder; mixing the first powder and the second powder and pressing the mixed powder to obtain a preform; and heating the preform at a high temperature. Degreasing The method includes processing the ceramic body to obtain a green body, cold isostatic pressing the green body, and then performing high-temperature sintering and polishing on the green body to obtain a fluorescent ceramic.

[0008] According to another aspect, the present application provides a light emitting device, the light emitting device including an excitation light source and the fluorescent ceramic described above, wherein the excitation light source is an incident laser light source.

[0009] According to yet another aspect, the present application provides a projection device, the projection device including the light emitting device described above. [Effects of the Invention]

[0010] The beneficial effects of the present invention are as follows: Unlike the prior art, the present invention uniformly distributes luminescent centers, first scattering units, and second scattering units with different refractive indices in the matrix of a fluorescent ceramic, with the first scattering units having a higher refractive index than the luminescent centers and the second scattering units having a lower refractive index. Because particle scattering ability depends on the particle dimensions and relative refractive indices, the incident laser light is scattered at the interfaces between the phases, which can enhance the refraction and scattering effects of the incident laser light and fluorescence within the fluorescent ceramic. This lengthens the optical path length of the excitation light in the ceramic and further weakens the lateral conduction of the fluorescence within the fluorescent ceramic. The fluorescence ultimately scatters from a small area near the incident laser light, i.e., the generated fluorescent spot is small, further improving the scattering performance of the fluorescent ceramic for fluorescence. [Brief explanation of the drawings]

[0011] In order to more clearly describe the technical solutions in the embodiments of the present application, the following briefly introduces drawings necessary for describing the embodiments, obviously, the drawings described below are only some embodiments of the present application, and those skilled in the art can obtain other drawings based on these drawings without any creative efforts, wherein: [Figure 1] 1 is a schematic diagram illustrating a configuration of a fluorescent ceramic according to an embodiment of the present invention. [Figure 2] 1 is a flowchart of an embodiment of a method for manufacturing a fluorescent ceramic according to the present invention. [Figure 3] 1 is a photograph of the microstructure of the fluorescent ceramic produced in Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0012] The technical solutions in the embodiments of the present application will be described below clearly and completely with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only some of the embodiments of the present application, not all of the embodiments, and any other embodiments that can be conceived by those skilled in the art based on the embodiments of the present application without any creative efforts are all included in the protection scope of the present application.

[0013] 1, which is a schematic diagram of one embodiment of the fluorescent ceramic of the present invention, includes at least a matrix 101, a luminescent center 102, a first scattering unit 103, and a second scattering unit 104. The luminescent center 102, the first scattering unit 103, and the second scattering unit 104 are distributed in the matrix 101.

[0014] Here, the matrix 101 may be made of a ceramic raw material, which may include one of aluminum oxide, aluminum nitride, silicon carbide, silicon nitride, and zirconium oxide, and which are characterized by a low refractive index, high thermal conductivity, high optical transparency, and the ability to withstand the temperatures during subsequent sintering. In another embodiment, the matrix 101 may be a cubic transparent ceramic with a garnet structure, and the luminescent center 102 may be a fluorescent powder with a garnet structure. When the luminescent center 102 and the matrix 101 both have a garnet structure, the luminescent performance and mechanical performance of the fluorescent ceramic can be optimized.

[0015] Preferably, the matrix 101 is an aluminum oxide matrix, and the luminescent centers 102 are fluorescent powders. Here, aluminum oxide belongs to a trigonal crystal system and exhibits birefringence, so that grain boundary birefringence occurs in the aluminum oxide matrix. The incident laser light is scattered by the grain boundary birefringence in the fluorescent ceramic, and the scattered incident laser light can excite more luminescent centers in its vicinity, further improving the luminous efficiency.

[0016] Furthermore, the inventors of the present application have found through long-term research and development that the refractive indexes of the aluminum oxide matrix and the fluorescent powder are both very close, between 1.7 and 1.8, which means that the incident laser light and fluorescent light inside the fluorescent ceramic are weakly refracted or scattered, and are easily transmitted laterally to the surroundings of the ceramic. This ultimately results in a large fluorescent spot in the fluorescent ceramic. If the light spot is highly diffused, the collection efficiency of the collecting lens will be low, which will affect the light utilization efficiency of the light source system.

[0017] Considering that particle scattering ability depends on particle dimensions and relative refractive index, the present inventors have developed a two-phase fluorescent ceramic based on aluminum oxide-phosphor powder, in which at least first and second scattering units, whose refractive indices are significantly different from those of the luminescent centers, are distributed in the matrix, and the refractive index of the first scattering unit is greater than that of the luminescent centers, while the refractive index of the second scattering unit is smaller than that of the luminescent centers. Due to the large difference in refractive index between the first scattering unit, the luminescent centers, and the second scattering unit in the fluorescent ceramic (obviously, the refractive index of the matrix is ​​close to that of the luminescent centers, and the refractive index differences between the first and second scattering units and the matrix are also large), the scattering of incident laser light at the interfaces between each phase is enhanced. By strengthening the refraction and scattering effects of the fluorescent ceramic on the incident laser light and fluorescence inside it, the optical path length of the excitation light in the ceramic is lengthened, and the lateral conduction of the fluorescence inside the fluorescent ceramic is weakened, so that the fluorescence is ultimately scattered from a small area near the incident laser light, i.e., the generated fluorescent spot is small, and the scattering performance of the fluorescent ceramic for fluorescence is further improved, thereby improving the light efficiency utilization rate of the light source system.

[0018] Furthermore, when different materials are selected for the luminescent center 102, first scattering unit 103, and second scattering unit 104, the refractive index difference between the first scattering unit 103 and the luminescent center 102 and the refractive index difference between the second scattering unit 104 and the luminescent center 102 are different and are not specifically limited. Here, the refractive index difference between the first scattering unit 103 and the luminescent center 102 may be 0.01 to 2.0, for example, 0.01, 0.4, 0.6, 0.8, or 2.0. The refractive index difference between the second scattering unit 104 and the luminescent center 102 may be 0.01 to 2.0, for example, 0.01, 0.4, 0.6, 0.8, or 2.0.

[0019] Unlike the prior art, the present invention provides a fluorescent ceramic matrix in which luminescent centers, first scattering units, and second scattering units with different refractive indices are uniformly distributed, with the first scattering units having a higher refractive index than the luminescent centers and the second scattering units having a lower refractive index than the luminescent centers. The particle scattering ability depends on the particle dimensions and relative refractive indices. The incident laser light is scattered at the interfaces between the phases, which enhances the refraction and scattering effects of the incident laser light and fluorescence within the fluorescent ceramic. This lengthens the optical path length of the excitation light within the ceramic and weakens the lateral conduction of the fluorescence within the fluorescent ceramic. The fluorescence ultimately scatters from a small area near the incident laser light, i.e., the generated fluorescent spot is small. This further improves the scattering performance of the fluorescent ceramic for fluorescence and improves the light utilization efficiency of the light source system.

[0020] In one embodiment, the first scattering units 103 are at least one of pores or first scattering particles.

[0021] Here, when the refractive index of the pores is 1 and the particle size of the pores is 0.2 to 2 μm, the scattering effect on the excitation light source is high. The particle size of the pores may be 0.2 μm, 0.8 μm, 1.0 μm, or 2.0 μm.

[0022] In this example, the pore diameter refers to the diameter of the pore when the pore is spherical, and when the pore is non-spherical, the pore diameter refers to the diameter of the smallest circumscribing sphere of the pore.

[0023] In order to avoid the light transmittance of the fluorescent ceramic being affected by too many or too few pores, in this embodiment, the volume fraction of pores in the fluorescent ceramic is 0.01% to 10%, for example, 0.01%, 0.1%, 1%, 5%, or 10%.

[0024] In one embodiment, the refractive index of the first scattering particles is 1.2 to 3.5, for example, 1.2, 1.7, 2.1, 2.5, or 3.5. The first scattering particles account for 0.1% to 1% of the total mass of the fluorescent ceramic, for example, 0.1%, 0.5%, 0.8%, or 1%.

[0025] Here, the first scattering particles may be at least one of titanium dioxide, zirconium oxide, yttrium oxide, calcium fluoride, and magnesium fluoride.

[0026] Furthermore, the second scattering units 104 may be at least one of pores or second scattering particles.

[0027] Here, when the refractive index of the pores is 1 and the particle size of the pores is 0.2 to 2 μm, the scattering effect on the excitation light source is high. The particle size of the pores may be 0.2 μm, 0.8 μm, 1.0 μm, or 2.0 μm.

[0028] In this example, the pore diameter refers to the diameter of the pore when the pore is spherical, and when the pore is non-spherical, the pore diameter refers to the diameter of the smallest circumscribing sphere of the pore.

[0029] In order to avoid the light transmittance of the fluorescent ceramic being affected by too many or too few pores, in this embodiment, the volume fraction of pores in the fluorescent ceramic is 0.01% to 10%, for example, 0.01%, 0.1%, 1%, 5%, or 10%.

[0030] In one embodiment, the refractive index of the second scattering particles is 1.2 to 2.5, for example, 1.2, 1.4, 1.6, 1.8, or 2.5. The second scattering particles account for 0.1% to 1% of the total mass of the fluorescent ceramic, for example, 0.1%, 0.5%, 0.8%, or 1%.

[0031] Here, the second scattering particles are at least one of calcium fluoride, magnesium fluoride, yttrium oxide, and zirconium oxide.

[0032] In one embodiment, in order to further improve the scattering effect of the fluorescent ceramic, the fluorescent ceramic further includes a third scattering unit (not shown) distributed in the matrix 101; Here, the refractive index of the third scattering unit is between the refractive index of the first scattering unit 103 and the refractive index of the second scattering unit 104 .

[0033] Furthermore, when different materials are selected for the luminescent center 102, first scattering unit 103, second scattering unit 104, and third scattering unit, the refractive index difference between the first scattering unit 103 and the third scattering unit, the refractive index difference between the second scattering unit 104 and the third scattering unit, and the refractive index difference between the luminescent center and the third scattering unit are different and are not specifically limited. Here, the absolute difference between the refractive index of the third scattering unit and the refractive index of the first scattering unit 103 is 0.6 to 1.5, for example, 0.6, 0.8, 1.0, or 1.5. The absolute difference between the refractive index of the third scattering unit and the refractive index of the second scattering unit 104 is 0.6 to 1.5, for example, 0.6, 0.8, 1.0, or 1.5.

[0034] Specifically, the third scattering units are at least one of pores and third scattering particles. The refractive index of the third scattering particles is 1.2 to 2.5, for example, 1.2, 1.4, 1.6, 1.8, or 2.5. The third scattering particles account for 0.1% to 1% of the total mass of the fluorescent ceramic, for example, 0.1%, 0.5%, 0.8%, or 1%.

[0035] In one embodiment, the luminescent centers 102 are lanthanoid-doped YAG phosphor particles with a particle size of 5 μm to 30 μm, for example, 5 μm, 10 μm, 20 μm, or 30 μm. The doping amount is 1% to 5%, for example, 1%, 2%, 3%, or 5%. The lanthanoid-doped YAG phosphor particles account for 40% to 50% of the total mass of the fluorescent ceramic, for example, 40%, 42%, 45%, or 50%.

[0036] Specifically, it can be understood that the luminescence intensity of the fluorescent ceramic cannot be guaranteed unless there is a sufficient amount of fluorescent powder as the luminescent centers 102. When the lanthanide-doped YAG phosphor particles account for 40% to 50% of the total mass of the fluorescent ceramic, the luminescent centers 102 have large crystal grain sizes, which improves the luminous efficiency, and the fluorescent ceramic has no impurity phases, pure grain boundaries, and high light uniformity, which can meet the needs of high-power light sources such as incident laser light. Furthermore, because scattering particles are added, when the incident laser light is irradiated on the scattering particles, the excitation light source is scattered, and after the scattering of the excitation light source, the optical path length of the excitation light in the ceramic is lengthened, thereby improving the light conversion efficiency.

[0037] The material of the matrix 101 is aluminum oxide having a particle size of 0.05 μm to 1 μm, for example, 0.05 μm, 0.1 μm, 0.5 μm, or 1.0 μm. The aluminum oxide accounts for 40% to 60% of the total mass of the fluorescent ceramic, for example, 40%, 50%, 55%, or 60%.

[0038] In one embodiment, the lanthanide element-doped YAG phosphor particles are YAG phosphor particles doped with Ce or Lu.

[0039] Specifically, in this embodiment, the YAG matrix 101 is doped with 1% to 5% Ce. In other embodiments, Lu may be doped, allowing the YAG matrix 101 to emit light and supplement the fluorescent ceramic. In this embodiment, the YAG matrix 101 is used as an adhesive medium to bond large-grain YAG phosphor particles. Adjusting the Ce or Lu content in the adhesive medium allows for the color coordinates of the fluorescent ceramic to be adjusted within a certain range. The doping contents of the YAG matrix 101 and the large-grain YAG phosphor particles are different, resulting in different fluorescent spectral ranges. The two complement each other, improving the color development with incident laser light. Furthermore, the fluorescent ceramic contains scattering particles with high refractive indexes, which are uniformly distributed in the fluorescent ceramic. When the incident laser light is irradiated onto the scattering particles, the excitation light is scattered. After scattering, the optical path length of the excitation light in the ceramic is lengthened, improving the light conversion efficiency.

[0040] 2 is a flowchart of an embodiment of a method for manufacturing a fluorescent ceramic according to the present invention. The present invention further provides a method for manufacturing a fluorescent ceramic, the method comprising the steps of: In S10, a matrix material of a fluorescent ceramic, a scattering material, and phosphor particles are prepared in a predetermined ratio.

[0041] Specifically, the matrix material can be aluminum oxide with a purity of 99.0% and a particle size of 0.05 μm to 1 μm, and the phosphor particles can be lanthanide-doped YAG phosphor particles with a purity of 99.0% and a particle size of 5 μm to 30 μm.

[0042] Here, the scattering material includes at least a pore-forming agent, first scattering particles, and second scattering particles.

[0043] The pore-forming agent is starch (particle size 0.1 μm to 10 μm, for example, 0.1 μm, 1 μm, or 10 μm) or PMMA microspheres (particle size 0.1 μm to 10 μm, for example, 0.1 μm, 1 μm, or 10 μm). The first scattering particles can be selected from at least one of titanium dioxide, zirconium oxide, yttrium oxide, calcium fluoride, or magnesium fluoride, all of which have a purity of 99.0%. The second scattering particles can be selected from at least one of calcium fluoride, magnesium fluoride, yttrium oxide, or zirconium oxide, all of which have a purity of 99.0%.

[0044] In S20, the matrix material and the scattering material are mixed in a first solvent and ball milled to obtain a first ball milled slurry.

[0045] Specifically, the matrix material and the scattering material are mixed in a predetermined ratio, and the mixture is placed in a ball milling tank using a first solvent as a liquid phase medium. The mixture is then mixed by ball milling at a rotation speed of 120 to 300 r / min for 1 to 4 hours to obtain a first ball milled slurry. The first solvent may be a mixture containing one or more of silicone oils such as phenyl and methyl groups, ethanol, ethylene glycol, xylene, ethyl cellulose, terpineol, butyl carbitol, PVA, PVB, PAA, and PEG.

[0046] In S30, the phosphor particles are mixed with a second solvent and ball milled to obtain a second ball milled slurry.

[0047] Specifically, 2The phosphor particles are placed in a ball milling tank using a solvent as a liquid phase medium, and ball milling mixing is performed at a rotation speed of 120 to 300 r / min for 0.5 to 4 hours to obtain a second ball mill slurry. The second solvent may be a mixture containing one or more of silicone oils such as phenyl and methyl groups, ethanol, ethylene glycol, xylene, ethyl cellulose, terpineol, butyl carbitol, PVA, PVB, PAA, and PEG.

[0048] In S40, the first ball mill slurry and the second ball mill slurry are dried, and after drying, crushing The mixture is then sieved to obtain a first powder and a second powder.

[0049] Specifically, before drying, the first and second ball mill slurries are vacuum degassed to obtain low-bubble, or even bubble-free, first and second ball mill slurries suitable for casting. The first and second ball mill slurries are then vacuum dried at a constant temperature to obtain dry powders, which are then calcined in a muffle furnace to remove organic components, and the powders are then sieved and granulated to obtain first and second powders.

[0050] In S50, the first powder and the second powder are mixed, and the mixed powder is pressed to obtain a preform.

[0051] Specifically, appropriate amounts of the first powder and the second powder are weighed and placed in a graphite mold, and the mixed powder is pressed. The pressing method is not particularly limited, and can be performed using a conventional pressing method, such as cold isostatic pressing. The pressing pressure is usually 5 MPa to 200 MPa, and preferably 15 MPa to 100 MPa. If the pressure is too low, pores will be numerous and large, which will affect the density of the final sintered product.

[0052] In S60, the preform is heated at high temperature. Degreasing By processing, the base material is obtained. Specifically, the crucible containing the preform is placed in a muffle furnace at a position adjacent to a thermocouple, Degreasing Begin the process. Degreasing The process is as follows: the temperature is raised to 200°C at a rate of 0.3°C / min to 0.6°C / min and maintained at that temperature for 0 to 2 hours to remove free water, crystal water, and other moisture in the body. The temperature is then raised to 500°C at a rate of 0.4°C / min to 0.7°C / min and maintained at that temperature for 0 to 3 hours to decompose and volatilize the organic matter in the body. The temperature is then raised to the densification temperature at a rate of 0.4°C / min to 0.7°C / min and maintained at that temperature for 2 to 6 hours. This process allows the ceramic body to develop a certain strength and prevent collapse. The densification temperature is generally set 300°C to 1000°C lower than the sintering temperature of the ceramic, preventing the sintering process between the raw material powder and the ceramic body and contributing to the removal of raw material powder. The cooling method is furnace cooling, and the atmosphere is air. Degreasing The process not only removes moisture and organic matter from the body, but also causes the body to shrink uniformly and achieves a certain degree of densification, with a volumetric shrinkage of 4% to 30% and a weight loss of 20% to 50%.

[0053] In S70, the substrate is subjected to cold isostatic pressing. specifically, Degreasing After this, the fluorescent ceramic base is subjected to cold isostatic pressing at a pressure of 150 MPa to 200 MPa to improve the density of the ceramic base.

[0054] In S80, the cold isostatically pressed body is subjected to high-temperature sintering and polishing to obtain fluorescent ceramics.

[0055] Clean Degreasing The ceramic body is placed back into the muffle furnace, heated to the sintering temperature at a rate of 1°C / min to 3°C / min, kept at that temperature for 1 to 12 hours, then cooled to room temperature together with the furnace in an air atmosphere. After polishing, fluorescent ceramics are obtained.

[0056] After the heat treatment, a fluorescent ceramic is obtained, and the manufacturing method further includes a reduction step for the fluorescent ceramic, which is carried out in a reducing atmosphere (e.g., a nitrogen / hydrogen mixed gas) at a temperature slightly lower than the sintering temperature of the heat treatment, i.e., 1200°C to 1650°C. The reduction process can remove impurities that have adhered to the fluorescent ceramic during the heat treatment step, preventing the impurities from becoming heat-generating centers in the operating environment of the fluorescent ceramic and affecting the use of the fluorescent ceramic.

[0057] Preferably, the matrix of the fluorescent ceramic may be an aluminum oxide matrix, and the luminescent center is a fluorescent powder. Aluminum oxide belongs to a trigonal crystal system and exhibits birefringence, so that grain boundary birefringence exists in the fluorescent ceramic with an aluminum oxide matrix. The incident laser light is scattered by the grain boundary birefringence in the fluorescent ceramic, and the scattered incident laser light can excite more luminescent centers in its vicinity, further improving the luminous efficiency.

[0058] Furthermore, the inventors of the present application have found through long-term research and development that the refractive indexes of the aluminum oxide matrix and the fluorescent powder are both very close, between 1.7 and 1.8, which means that the incident laser light and fluorescent light inside the fluorescent ceramic are weakly refracted or scattered, and are easily transmitted laterally to the surroundings of the ceramic. This ultimately results in a large fluorescent spot in the fluorescent ceramic. If the light spot is highly diffused, the collection efficiency of the collecting lens will be low, which will affect the light utilization efficiency of the light source system.

[0059] Considering that particle scattering ability depends on particle dimensions and relative refractive index, the present inventors have developed a two-phase fluorescent ceramic based on aluminum oxide-phosphor powder, in which at least first and second scattering units, whose refractive indices are significantly different from those of the luminescent centers, are distributed in the matrix, and the refractive index of the first scattering unit is greater than that of the luminescent centers, while the refractive index of the second scattering unit is smaller than that of the luminescent centers. Due to the large difference in refractive index between the first scattering unit, the luminescent centers, and the second scattering unit in the fluorescent ceramic (obviously, the refractive indices of the matrix and the luminescent centers are close, and the refractive index differences between the first and second scattering units and the matrix are also large), the scattering of incident laser light at the interfaces between each phase is enhanced. By strengthening the refraction and scattering effects of the fluorescent ceramic on the incident laser light and fluorescence inside it, the optical path length of the excitation light in the ceramic is lengthened, and the lateral conduction of the fluorescence inside the fluorescent ceramic is weakened, so that the fluorescence is ultimately scattered from a small area near the incident laser light, i.e., the generated fluorescent spot is small, and the scattering performance of the fluorescent ceramic for fluorescence is further improved, thereby improving the light efficiency utilization rate of the light source system.

[0060] Unlike the prior art, the present invention provides a fluorescent ceramic matrix in which luminescent centers, first scattering units, and second scattering units with different refractive indices are uniformly distributed, with the first scattering units having a higher refractive index than the luminescent centers and the second scattering units having a lower refractive index than the luminescent centers. The particle scattering ability depends on the particle dimensions and relative refractive indices. The incident laser light is scattered at the interfaces between the phases, which enhances the refraction and scattering effects of the fluorescent ceramic on the incident laser light and fluorescence. This lengthens the optical path length of the excitation light in the ceramic and weakens the lateral conduction of the fluorescence within the fluorescent ceramic. The fluorescence ultimately scatters from a small area near the incident laser light, i.e., the generated fluorescent spot is small. This further improves the scattering performance of the fluorescent ceramic for fluorescence, thereby improving the light efficiency of the light source system.

[0061] The present application will be further described in detail below with reference to examples. It is also to be understood that the following examples are merely for the purpose of further illustrating the present application and should not be construed as limiting the scope of protection of the present application, and any non-essential improvements and adjustments made by those skilled in the art based on the above content of the present application are also included in the scope of protection of the present application. The specific process parameters etc. in the following examples are also merely examples of suitable ranges, that is, those skilled in the art can select within the appropriate ranges based on the description in this specification, and are not limited to the specific numerical values ​​in the following examples.

[0062] Example 1 Select aluminum oxide powder, zirconium oxide powder, and magnesium fluoride powder with a purity of 99.0% or more, and weigh out 99.0% aluminum oxide powder, 0.5% zirconium oxide powder, and 0.5% magnesium fluoride powder according to the mass percentage. Then, use a wet ball mill method to mix the powdered raw materials using anhydrous ethanol as a medium. crushing The ball milling time is set to 24 hours to obtain a first ball milled slurry.

[0063] The YAG:Ce fluorescent powder was weighed, where the YAG:Ce fluorescent powder accounted for 50% of the total powder mass of the fluorescent ceramics, and the mixed powder raw material was then mixed with the PVB ethanol solution as a medium by the wet ball mill method. crushing The ball milling time was set to 1 hour to obtain a second ball mill slurry. Here, the mass percentage of PVB in the PVB ethanol solution was 0.5% to 2%. Mass percentage refers to the percentage of the mass of a substance relative to the total mass, and in this case, it refers to the percentage value of the mass of PVB relative to the total mass of the solution consisting of PVB and ethanol.

[0064] Vacuum drying was carried out at 70°C, and immediately afterwards crushing The powder is then processed by sieving and stored for use.

[0065] The mixed fluorescent ceramic powder is pressed at a pressure of 80 MPa to produce a block. The formed ceramic body is then placed in a muffle furnace. Degreasing Process and DegreasingThe process involves holding the temperature at 500°C for 2 hours and then at 900°C for 4 hours. Degreasing After completion, the fluorescent ceramic base is subjected to cold isostatic pressing at a pressure of 200 MPa to improve the density of the ceramic base.

[0066] The ceramic base material is placed in a vacuum furnace and the vacuum level is set to 10 -3 After vacuum sintering, the fluorescent ceramics are annealed in an air atmosphere at 1300°C for 10 hours, and then thinned and polished to obtain usable fluorescent ceramics.

[0067] Example 2 Select aluminum oxide powder with a purity of 99.9% or more, titanium oxide with a purity of 99%, and a pore-forming agent. According to the mass percentage, 98.0% of aluminum oxide powder, 1.0% of titanium oxide powder, and 1.0% of the pore-forming agent are weighed, and mixed powder raw materials are mixed using anhydrous ethanol as a medium. crushing The ball milling time is set to 24 hours to obtain a first ball milled slurry.

[0068] The YAG:Ce fluorescent powder was weighed, where the YAG:Ce fluorescent powder accounted for 40% of the total powder mass of the fluorescent ceramics, and the mixed powder raw material was then mixed with the PVB ethanol solution as a medium by the wet ball mill method. crushing The ball milling time was set to 0.5 hours to obtain a second ball mill slurry. Here, the mass percentage of PVB in the PVB ethanol solution was 0.5% to 2%. Mass percentage refers to the percentage of the mass of a substance relative to the total mass, and in this case, it refers to the percentage value of the mass of PVB relative to the total mass of the solution consisting of PVB and ethanol.

[0069] Vacuum drying was carried out at 60°C, and immediately afterwards crushing The powder is then processed by sieving and stored for use.

[0070] The mixed fluorescent ceramic powder is pressed at a pressure of 50 MPa to produce a block. The formed ceramic body is then placed in a muffle furnace. DegreasingProcess and Degreasing The process involves holding the temperature at 600°C for 2 hours and then at 1000°C for 6 hours. Degreasing After completion, the fluorescent ceramic base is subjected to cold isostatic pressing at a pressure of 180 MPa to improve the density of the ceramic base.

[0071] The ceramic base material is placed in a vacuum furnace and the vacuum level is set to 10 -3 Pa and sintered at 1600°C for 4 hours. After vacuum sintering, the fluorescent ceramics are annealed in an air atmosphere at 1350°C for 10 hours, and then thinned and polished to obtain usable fluorescent ceramics.

[0072] Referring to Figure 3, Figure 3 is a microstructure photograph of the fluorescent ceramic produced in Example 2. As can be seen from the figure, the phosphor particles uniformly dispersed in the aluminum oxide ceramic matrix have been removed, and a small amount of a low refractive index phase (pores) and a high refractive index phase (titanium oxide) are present.

[0073] Example 3 Aluminum oxide powder, magnesium fluoride, titanium oxide, and zirconium oxide with a purity of 99.9% or more were selected, and 99.0% aluminum oxide powder, 0.30% magnesium fluoride, 0.30% titanium oxide, and 0.40% zirconium oxide were weighed according to the mass percentage. The mixed powder raw materials were then mixed using anhydrous ethanol as a medium by a wet ball mill method. crushing The ball milling time is set to 36 hours to obtain a first ball milled slurry.

[0074] The YAG:Ce fluorescent powder was weighed, where the YAG:Ce fluorescent powder accounted for 60% of the total powder mass of the fluorescent ceramics, and the mixed powder raw material was then mixed with the PVB ethanol solution as a medium by the wet ball mill method. crushingThe ball milling time was set to 0.5 hours to obtain a second ball mill slurry. Here, the mass percentage of PVB in the PVB ethanol solution was 0.5% to 2%. Mass percentage refers to the percentage of the mass of a substance relative to the total mass, and in this case, it refers to the percentage value of the mass of PVB relative to the total mass of the solution consisting of PVB and ethanol.

[0075] Vacuum drying was carried out at 70°C, and immediately afterwards crushing The powder is then processed by sieving and stored for use.

[0076] The ceramic powder is filled into a graphite mold and pre-pressed at a pressure of 5 to 20 MPa. The graphite mold is then placed in an SPS hot press furnace and sintered in a vacuum / argon atmosphere at 1200 to 1600°C for 0.5 to 4 hours, with the sintering pressure being 20 to 150 MPa. After hot press sintering, the fluorescent ceramic is annealed in an air atmosphere at 1300°C for 10 hours, and then thinned and polished to obtain a usable fluorescent ceramic.

[0077] Comparative Example Select aluminum oxide powder and YAG:Ce fluorescent powder with a purity of 99.9% or more, and weigh out 50.0% aluminum oxide powder and 50.0% YAG:Ce fluorescent powder according to the mass percentage. Then, use a wet ball mill method to mix the powdered raw materials using anhydrous ethanol as a medium. crushing The ball milling time is set to 36 hours to obtain a slurry.

[0078] Vacuum drying was carried out at 70°C, and immediately afterwards crushing The powder is then processed by sieving and stored for use.

[0079] The ceramic powder is filled into a graphite mold and pre-pressed at a pressure of 50MPa to 20MPa. The graphite mold is then placed in an SPS hot press furnace and sintered at 1200℃ to 1600℃ in a vacuum / argon atmosphere for 0.5h to 4h. The pressure during sintering is: 20After hot press sintering, the fluorescent ceramic is annealed in an air atmosphere at 1300°C for 10 hours, and then thinned and polished to obtain a usable fluorescent ceramic.

[0080] Example 4 The fluorescent ceramics produced in Examples 1, 2, and 3, as well as the fluorescent ceramics that were not optimized (i.e., the comparative example), were processed into test samples and placed on a test platform for comparative testing. The test results obtained are shown in the table below. The luminous efficiency in the table specifically refers to the optical power conversion efficiency of incident blue laser light.

[0081] [Table 1]

[0082] As can be seen from the above table, in Examples 1 to 3, the luminescent center, first scattering unit, and second scattering unit, which have different refractive indices, are uniformly distributed in the matrix of the fluorescent ceramic, and the refractive indexes of the first scattering unit, luminescent center, and second scattering unit are significantly different within the matrix (as can be seen, the refractive index of the matrix is ​​close to that of the luminescent center, and therefore the refractive indexes of the first scattering unit and second scattering unit are significantly different from that of the matrix). This results in the particle scattering ability depending on the particle dimensions and relative refractive index, and the incident laser light is scattered at the interfaces between the phases, thereby enhancing the refraction and scattering effects of the incident laser light and fluorescence within the fluorescent ceramic. This lengthens the optical path length of the excitation light within the ceramic and further weakens the lateral conduction of the fluorescence within the fluorescent ceramic, resulting in the fluorescence being scattered from a small area near the incident laser light. This means that the generated fluorescent spot is smaller, further improving the scattering performance of the fluorescent ceramic for fluorescence and improving the light efficiency of the light source system.

[0083] The present application further provides a light-emitting device, comprising an excitation light source and the above-mentioned fluorescent ceramic, wherein the excitation light source is an incident laser light source that irradiates the fluorescent ceramic to generate high-brightness light. The light-emitting device may be applied to projection and display systems, such as liquid crystal display (LCD) or digital light processor (DLP) projectors, lighting systems, such as automotive lighting, and 3D display technology. In the light-emitting device, the fluorescent ceramic may be fabricated as a movable device, such as a color wheel, and the excitation light emitted from the excitation light source is incident on the rotating color wheel to generate incident laser light.

[0084] The present application further provides a projection device, which may be an educational projector, a laser television, a micro-projector, or a broadcasting machine, etc., and which includes the light-emitting device of the above embodiment, and the specific configuration of the light-emitting device shall refer to the above embodiment.

[0085] The above is merely an example of the present application and does not limit the scope of the claims of the present application. Any equivalent configuration or equivalent flow conversion made using the contents of the specification and drawings of the present application, or any direct or indirect application to other related technical fields, is also included within the scope of the claims of the present application.

Claims

1. A fluorescent ceramic, The fluorescent ceramic includes at least a matrix, a luminescent center, a first scattering unit, and a second scattering unit distributed in the matrix, the refractive index of the first scattering unit is greater than the refractive index of the luminescent center; The refractive index of the second scattering unit is smaller than the refractive index of the luminescent center. the matrix is ​​an aluminum oxide matrix, and the luminescent center is a YAG phosphor particle doped with a lanthanoid element; The first scattering unit is a first scattering particle, and the refractive index of the first scattering particle is 2.5 to 3.5; The fluorescent ceramics is characterized in that the second scattering units are second scattering particles, and the refractive index of the second scattering particles is 1.2 to 1.

6.

2. 2. The fluorescent ceramic according to claim 1, wherein the mass of the first scattering particles accounts for 0.1% to 1% of the total mass of the fluorescent ceramic.

3. 2. The fluorescent ceramic of claim 1, wherein the first scattering particles are titanium dioxide.

4. 2. The fluorescent ceramic according to claim 1, wherein the mass of the second scattering particles accounts for 0.1% to 1% of the total mass of the fluorescent ceramic.

5. 2. The fluorescent ceramic according to claim 1, wherein the second scattering particles are calcium fluoride, magnesium fluoride, or a combination of calcium fluoride and magnesium fluoride.

6. 2. The fluorescent ceramic of claim 1, further comprising a third refractive index unit, the third refractive index unit being distributed within the matrix and having a refractive index between the refractive index of the first scattering unit and the refractive index of the second scattering unit.

7. the luminescent center is a lanthanoid-doped YAG phosphor particle having a particle size of 5 μm to 30 μm, the doping amount is 1% to 5%, and the mass of the lanthanoid-doped YAG phosphor particle accounts for 40% to 50% of the total mass of the fluorescent ceramic; 2. The fluorescent ceramic according to claim 1, wherein the matrix material is aluminum oxide having a particle size of 0.05 μm to 1 μm, and the mass of the aluminum oxide accounts for 40% to 60% of the total mass of the fluorescent ceramic.

8. 8. The fluorescent ceramic according to claim 7, wherein the lanthanoid-doped YAG phosphor particles are YAG phosphor particles doped with Ce or Lu.

9. A method for producing a fluorescent ceramic, wherein the fluorescent ceramic is the fluorescent ceramic according to any one of claims 1 to 8, The manufacturing method includes: A fluorescent ceramic matrix material, a scattering material, and phosphor particles are prepared in a predetermined ratio, wherein the scattering material includes at least a pore-forming agent, first scattering particles, and second scattering particles; mixing the matrix material and the scattering material in a first solvent and ball milling the mixture to obtain a first ball milled slurry; mixing the phosphor particles with a second solvent and ball milling the mixture to obtain a second ball milled slurry; drying the first ball mill slurry and the second ball mill slurry, respectively, and then pulverizing and sieving the first and second ball mill slurries to obtain a first powder and a second powder; mixing the first powder and the second powder and pressing the mixed powder to obtain a preform; subjecting the preform to a high-temperature degreasing treatment to obtain a base material; cold isostatically pressing the substrate; and subjecting the cold isostatically pressed base to high-temperature sintering and polishing, and then obtaining the fluorescent ceramic.

10. A light emitting device, comprising: A light emitting device comprising an excitation light source and the fluorescent ceramic according to any one of claims 1 to 8, wherein the excitation light source is an incident laser light source.

11. 1. A projection device, comprising: A projection device comprising the light emitting device according to claim 10.

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