Light-emitting ceramic, preparation method, wavelength conversion device, and light-emitting device

Abstract

The present application discloses a light-emitting ceramic, a preparation method, a wavelength conversion device, and a light-emitting device. The light-emitting ceramic comprises fluorescent powder crystal grains, matrix ceramic crystal grains, and fluorescent grain boundary phases, and the fluorescent grain boundary phases are located between the matrix ceramic crystal grains or / and between the matrix ceramic crystal grains and the fluorescent powder crystal grains. By providing the fluorescent powder crystal grains, the matrix ceramic crystal grains, and the grain boundary phases, the present application can improve the sintering compactness of fluorescent ceramics, and can effectively improve the thermal diffusion of the fluorescent ceramics, obtain a relatively high saturation threshold, keep a relatively high thermal conductivity, and improve the light-emitting efficiency.

Description

Luminescent ceramic, preparation method, wavelength conversion device and luminescent device Technical Field

[0001] The present application relates to the technical field of luminescent ceramic material preparation, and in particular to a luminescent ceramic, a preparation method, a wavelength conversion device and a light-emitting device. Background Art

[0002] Laser lighting technology has the advantages of high brightness, long irradiation distance, higher conversion efficiency and longer service life. In the near future, laser lighting may replace the current LED lighting and set off a new round of lighting technology revolution.

[0003] At present, the mainstream technology in the field of laser light sources has gradually developed into blue laser excitation of fluorescent materials to achieve wavelength conversion and obtain white light, but traditional yellow, green and red phosphors are difficult to achieve stable luminescence under continuous irradiation of high-intensity lasers. In recent years, with the rapid development of luminescent ceramics, luminescent ceramics are regarded as one of the most suitable fluorescent materials for high-power laser lighting due to their excellent luminescence and thermal shock resistance. However, as the laser power becomes higher and higher, luminescent ceramics not only have to withstand the thermal shock of high power density, but also have to withstand irradiation with high optical power density. Therefore, luminescent ceramics are required to have not only excellent luminous efficiency, but also excellent light extraction efficiency, thermal saturation performance and light saturation performance. This puts higher requirements on the luminous efficiency, light extraction efficiency, thermal saturation performance and light saturation performance of luminescent ceramics.

[0004] Summary of the Invention

[0005] In view of this, the present application provides a luminescent ceramic and a preparation method to solve the problem that luminescent ceramic modules have difficulty in balancing luminous efficiency, light extraction efficiency, thermal saturation performance and light saturation performance.

[0006] The present application provides a luminescent ceramic comprising phosphor grains, matrix ceramic grains and a phosphor grain boundary phase, wherein the phosphor grain boundary phase is located between the matrix ceramic grains or / and between the matrix ceramic grains and the phosphor grains.

[0007] Optionally, the fluorescent grain boundary phase includes at least one of a first fluorescent grain boundary phase, a second fluorescent grain boundary phase, and a third fluorescent grain boundary phase;

[0008] The first fluorescent grain boundary phase is located between the matrix ceramic grains, the second fluorescent grain boundary phase is arranged between the matrix ceramic grains and the fluorescent powder grains, and the third fluorescent grain boundary phase is enclosed at the periphery of the fluorescent powder grains.

[0009] Optionally, the fluorescent grain boundary phase accounts for 5% to 20% of the total volume of the luminescent ceramic.

[0010] Optionally, the first fluorescent grain boundary phase accounts for 5% to 40% of the total volume of the grain boundary phase;

[0011] or / and the second fluorescent grain boundary phase accounts for 5% to 40% of the total volume of the grain boundary phase;

[0012] Or / and the third fluorescent grain boundary phase accounts for 5% to 40% of the total volume of the grain boundary phase.

[0013] Optionally, the fluorescent grain boundary phase includes a first matrix phase doped with a first luminescent ion;

[0014] The phosphor crystal particles include a second matrix phase doped with a second luminescent ion;

[0015] The first luminescent ion is the same as or different from the second luminescent ion;

[0016] Or / and the first matrix phase is the same as or different from the second matrix phase.

[0017] Optionally, the first matrix phase and the second matrix phase are oxide garnet phases; the first luminescent ions and the second luminescent ions are cerium ions.

[0018] Optionally, the molar doping concentration of the first luminescent ion is 0.02% to 5%; or / and the molar doping concentration of the second luminescent ion is 0.01% to 10%;

[0019] Optionally, the molar doping concentration of the first light-emitting ions is less than the molar doping concentration of the second light-emitting ions.

[0020] Optionally, the volume content of the phosphor particles is 10% to 90%;

[0021] Or / and the size of phosphor particles is 5 to 20 μm.

[0022] This application also proposes a method for preparing a luminescent ceramic, the preparation method comprising:

[0023] preparing fluorescent grain boundary phase raw materials, mixing, sintering and crushing the fluorescent grain boundary phase raw materials to obtain fluorescent grain boundary phase powder;

[0024] preparing phosphor particles, matrix ceramic powder and sintering aids, mixing, calcining and molding the phosphor grain boundary phase powder, phosphor particles, matrix ceramic powder and sintering aids to obtain a ceramic body;

[0025] sintering the ceramic body to obtain a luminescent ceramic block;

[0026] The luminescent ceramic block is annealed and surface treated to obtain the luminescent ceramic.

[0027] The present application also proposes a wavelength conversion device, comprising a luminescent ceramic layer, wherein the luminescent ceramic layer is made of the above luminescent ceramic.

[0028] The present application also proposes a light-emitting device, comprising an excitation light source and the wavelength conversion device as described above.

[0029] The beneficial effects of the present application are as follows: Different from the prior art, the luminescent ceramic of the present application includes phosphor grains, matrix ceramic grains and grain boundary phases, and the grain boundary phases are located between the matrix ceramic grains or / and between the matrix ceramic grains and the phosphor grains. The present application can improve the sintering density of the phosphor ceramic by introducing the grain boundary phase phosphor grains, thereby improving the thermal conductivity of the luminescent ceramic and improving the thermal saturation performance. At the same time, the grain boundary phase can enhance the scattering of the excitation light incident on the phosphor ceramic, thereby improving the light extraction efficiency of the luminescent ceramic. The grain boundary phase can also emit light and can serve as a luminescence efficiency enhancement phase or color complementary phase of the phosphor grains, thereby improving the luminescence efficiency and achieving spectral diversity. Secondly, the present application can improve the light extraction efficiency by setting the matrix ceramic grains to form light scattering centers, and the high thermal conductivity matrix ceramic grains can also effectively enhance the thermal diffusion of the luminescent ceramic, obtain a higher thermal saturation threshold, and show higher reliability under high power density excitation light excitation. At the same time, due to the improvement of the thermal saturation threshold and the improvement of the luminescence efficiency, the luminescent ceramic of the present application can obtain a better light saturation threshold. Therefore, the luminescent ceramic of the present application takes into account luminous efficiency, light extraction efficiency, thermal saturation performance and light saturation performance.

[0030] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0032] FIG1 is a schematic structural diagram of an embodiment of the luminescent ceramic of the present application;

[0033] FIG2 is a magnified microscope view of an embodiment of the luminescent ceramic of the present application;

[0034] FIG3 is a magnified microscope view of an embodiment of the luminescent ceramic of the present application;

[0035] FIG4 is a flow chart of an embodiment of the preparation method of the present application;

[0036] FIG5 is a specific flow chart of step S100 in FIG4 ;

[0037] FIG6 is a specific flow chart of step S200 in FIG4 . DETAILED DESCRIPTION

[0038] To help those skilled in the art better understand the technical solutions of this application, the luminescent ceramics and preparation methods provided by this application are further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the embodiments described are only some of the embodiments of this application, and not all of them. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without inventive effort are within the scope of protection of this application.

[0039] The terms "first," "second," and the like in this application are used to distinguish between different objects, not to describe a particular order. Furthermore, the terms "including," "having," and any variations thereof, are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus comprising a series of steps or elements is not limited to the listed steps or elements, but may optionally include steps or elements not listed, or may optionally include other steps or elements inherent to the process, method, product, or apparatus.

[0040] The present application provides a luminescent ceramic, a preparation method, a wavelength conversion device and a luminescent device to solve the problem that the luminescent ceramic module has a high fluorescence efficiency and a high light saturation power density and a high thermal conductivity.

[0041] Please refer to Figures 1 to 6, Figure 1 is a structural schematic diagram of an embodiment of the luminescent ceramic of the present application; Figure 2 is a microscopic magnified view of an embodiment of the luminescent ceramic of the present application; Figure 3 is a microscopic magnified view of an embodiment of the luminescent ceramic of the present application; Figure 4 is a flow chart of an embodiment of the preparation method of the present application; Figure 5 is a specific flow chart of step S100 in Figure 4; Figure 6 is a specific flow chart of step S200 in Figure 4.

[0042] The present application provides a luminescent ceramic. In one embodiment, as shown in FIG1 , the luminescent ceramic includes phosphor grains 10, matrix ceramic grains 20, and phosphor grain boundary phases 30. The phosphor grain boundary phases 30 may be located between two matrix ceramic grains 20 or / and between a matrix ceramic grain 20 and a phosphor grain 10.

[0043] It can be understood that the luminescent ceramic of the present application includes phosphor grains 10, matrix ceramic grains 20 and fluorescent grain boundary phases 30. At the same time, the fluorescent grain boundary phase 30 is located between two matrix ceramic grains 20; or the fluorescent grain boundary phase 30 is located between the matrix ceramic grains 20 and the phosphor grains 10 to form the structure of the luminescent ceramic. The fluorescent grain boundary phase 30 can improve the sintering density of the fluorescent ceramic, while improving the light extraction efficiency of the ceramic and increasing the spectral diversity. The matrix ceramic grains 20 form light scattering centers, which can limit the diffusion of the fluorescent spot, maintain a high thermal conductivity, and ultimately improve the light extraction efficiency. It can also effectively improve the thermal diffusion of the fluorescent ceramic, obtain a higher thermal saturation threshold, and show higher reliability under high power density excitation light excitation. At the same time, due to the improvement of the thermal saturation threshold and the improvement of the luminous efficiency, the luminescent ceramic of the present application can obtain a better light saturation threshold.

[0044] In some embodiments, as shown in Figures 1 to 3, the fluorescent grain boundary phase 30 includes at least one of a first fluorescent grain boundary phase 31, a second fluorescent grain boundary phase 32, and a third fluorescent grain boundary phase 33. The first fluorescent grain boundary phase 31 is located between two host ceramic grains 20, the second fluorescent grain boundary phase 32 is located between a phosphor grain 10 and a host ceramic grain 20, and the third fluorescent grain boundary phase 33 is located around the outer periphery of the phosphor grain 10, i.e., around the outer circumference of the phosphor grain 10. It is understood that a fluorescent grain boundary phase 30 that completely envelops or covers a phosphor grain 10 is categorized as the third fluorescent grain boundary phase 33. A fluorescent grain boundary phase 30 that does not completely envelop or cover a phosphor grain 10 but is located between the phosphor grain 10 and the host ceramic grain 20 is categorized as the second fluorescent grain boundary phase 32. The luminescent ceramic may include only one of the first fluorescent grain boundary phase 31, the second fluorescent grain boundary phase 32, and the third fluorescent grain boundary phase 33, or may include two types of fluorescent grain boundary phases 30. Preferably, the first fluorescent grain boundary phase 31, the second fluorescent grain boundary phase 32, and the third fluorescent grain boundary phase 33 coexist in the luminescent ceramic. In addition, the luminescent ceramic may also include a fourth fluorescent grain boundary phase located between two phosphor grains 10. The fluorescent grain boundary phase 30 that does not completely envelop or cover the phosphor grains 10 but is located between the phosphor grains 10 is classified as the fourth fluorescent grain boundary phase. This phase may exist alone in the luminescent ceramic or coexist with at least one of the first fluorescent grain boundary phase 31, the second fluorescent grain boundary phase 32, and the third fluorescent grain boundary phase 33.

[0045] Since the fluorescent grain boundary phase 30 is formed between the matrix ceramic grains 20, between the phosphor grains 10, or between the matrix ceramic grains 20 and the phosphor grains 10, when sintering to manufacture the luminescent ceramic, the fluorescent grain boundary phase 30 can effectively fill the pores between the matrix ceramic grains 20, between the phosphor grains 10, or between the matrix ceramic grains 20 and the phosphor grains 10, thereby improving the sintering density of the luminescent ceramic. If the volume fraction of the fluorescent grain boundary phase 30 is too small, the effect is not obvious. If the volume fraction of the fluorescent grain boundary phase 30 is too large and the matrix ceramic grains 20 are relatively small, it is not conducive to the heat dissipation of the luminescent ceramic, and may also have an adverse effect on the overall mechanical strength of the luminescent ceramic; the fluorescent grain boundary phase 30 can emit light under the excitation of the excitation light, and thus can also adjust the spectrum of the luminescent ceramic, improve the diversity of the spectrum, and can serve as a fluorescence efficiency enhancement phase or a color complementary phase; in addition, considering that the fluorescent grain boundary phase 30 is only an auxiliary luminescent phase, the main luminescent phase in the luminescent ceramic is the phosphor grains 10, if the fluorescent grain boundary phase 30 is too much and the phosphor grains 10 are relatively small, it will affect the overall luminescent efficiency of the luminescent ceramic; when the fluorescent grain boundary phase 30 and the matrix ceramic grains 20 are made of different materials, due to the different refractive indices of the fluorescent grain boundary phase 30 and the matrix ceramic grains 20, the scattering of the excitation light can be enhanced and the light extraction efficiency can be improved. Therefore, the fluorescent grain boundary phase 30 preferably accounts for 5% to 20% of the total volume of the luminescent ceramic, for example, 5%, 6%, 7%, 8%, 9%, 10%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, or any range therebetween. It should be noted that the volume ratio of the fluorescent grain boundary phase 30 can be determined by classifying and counting the proportion of the fluorescent grain boundary phase 30 in the observed area using software such as ImageJ, as shown in FIG3 . The volume ratio of the phosphor grains 10 and the matrix ceramic grains 20 in the luminescent ceramic can also be determined in a similar manner.

[0046] In some embodiments, the first fluorescent grain boundary phase 31 may be located between two matrix ceramic grains 20 and may be formed by aggregation of independently dispersed particles of the fluorescent grain boundary phase 30. The first fluorescent grain boundary phase 31 may account for 5-40% of the total volume of the fluorescent grain boundary phase 30. Alternatively, the first fluorescent grain boundary phase 31 may account for 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, or any range therebetween. If the volume fraction of the first fluorescent grain boundary phase 31 is too high, it may hinder heat conduction between the matrix ceramic grains 20, thereby hindering heat dissipation of the luminescent ceramic and may also adversely affect the overall mechanical strength of the luminescent ceramic. If the volume fraction is too low, the effects of increasing sintering density, enhancing spectral diversity, and improving light scattering, thereby improving light extraction efficiency, may not be significant.

[0047] In some embodiments, the second fluorescent grain boundary phase 32 may be disposed between the matrix ceramic grains 20 and the phosphor grains 10, and the second fluorescent grain boundary phase 32 may be formed by the aggregation of fluorescent grain boundary phase 30 particles around the phosphor grains 10. The second fluorescent grain boundary phase 32 may comprise 5% to 40% of the total volume of the fluorescent grain boundary phase 30. Alternatively, the second fluorescent grain boundary phase 32 may comprise 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, or any range therebetween. If the volume fraction of the second fluorescent grain boundary phase 32 is too high, it may hinder the excitation light from passing through the second fluorescent grain boundary phase 32 and entering the phosphor grains 10, which are the primary luminescent phase, to excite and emit light, thereby hindering the improvement of overall luminous efficiency. If the volume fraction is too low, the effects of improving sintering density, spectral diversity, and light scattering, thereby improving light extraction efficiency, may not be significant.

[0048] In some embodiments, the third fluorescent grain boundary phase 33 may be disposed around the outer circumference of the phosphor grain 10. The third fluorescent grain boundary phase 33 may be formed by a certain degree of mutual fusion of the fluorescent grain boundary phase 30 particles around the phosphor grain 10. The third fluorescent grain boundary phase 33 may account for 5-40% of the total volume of the fluorescent grain boundary phase 30. The third fluorescent grain boundary phase 33 may also account for 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, or any range therebetween of the total volume of the fluorescent grain boundary phase 30. If the volume proportion of the third fluorescent grain boundary phase 33 is too high, it may be difficult for the excitation light to pass through the third fluorescent grain boundary phase 33 and enter the phosphor grain 10, which is the main luminescent phase, to excite and emit light, thereby hindering the improvement of the overall luminous efficiency. If the volume proportion is too small, the effect of improving the sintering density or increasing the spectral diversity may not be significant.

[0049] In some embodiments, the fluorescent grain boundary phase 30 includes a first matrix phase doped with a first luminescent ion, and the phosphor grains 10 include a second matrix phase doped with a second luminescent ion, and the first luminescent ions and the second luminescent ions can be the same or different, or / and the first matrix phase and the second matrix phase can be the same or different. For example, in one embodiment, the materials of the first matrix phase and the second matrix phase, the first luminescent ions and the second luminescent ions can be exactly the same. In this case, the phosphor grains 10 and the fluorescent grain boundary phase 30 produce the same color of excitation light under the excitation of the excitation light. The fluorescent grain boundary phase 30 can serve as a fluorescence efficiency enhancement phase for the phosphor grains 10, so that the fluorescent grain boundary phase 30 and the phosphor grains 10 in the luminescent ceramic simultaneously emit light under the excitation of the excitation light, which can improve the overall luminescence efficiency of the luminescent ceramic. In other embodiments, the first matrix phase and the second matrix phase may be the same, and the types of the first luminescent ion and the second luminescent ion may be different, or the first matrix phase and the second matrix phase may be different, and the types of the first luminescent ion and the second luminescent ion may be the same, or the first matrix phase and the second matrix phase, the types of the first luminescent ion and the second luminescent ion are all different. At this time, the phosphor grains 10 and the phosphor grain boundary phases 30 generate excitation light with different colors or different spectra under the excitation of the excitation light. The phosphor grain boundary phase 30 can serve as the color complementary phase of the phosphor grains 10. The phosphor grain boundary phase 30 can adjust the spectrum of the phosphor grains 10, which can enhance the diversity of the luminescence spectrum of the luminescent ceramic. In one embodiment, the first luminescent ions and the second luminescent ions can be rare earth ions or transition metal ions, such as Mn (manganese), Ce (cerium), Eu (europium), Yb (ytterbium), Nd (neodymium), Gd (gadolinium), Sm (samarium), Tb (terbium), Dy (dysprosium), Ho (holmium), Er (erbium), Tm (thulium), etc.; the first matrix phase and the second matrix phase can be aluminates, silicates, tungstates, phosphates, nitrides, etc.

[0050] Optionally, the first luminescent ion includes a cerium ion, and the first matrix phase includes an oxide garnet phase. The cerium ion may be doped in the oxide garnet phase, and the oxide garnet phase may be Y3Al5O 12 (yttrium aluminate, abbreviated as YAG), Lu3Al5O 12 (lutetium aluminum garnet, abbreviated as LuAG), Gd3(Al,Ga)5O 12 (cerium-doped gadolinium gallium aluminate, abbreviated as GAGG), etc., the oxide garnet phase can be one or more of them, as the fluorescence efficiency enhancement phase or color complementary phase of the phosphor crystal grain 10.

[0051] Optionally, the second luminescent ion includes a cerium ion, and the second matrix phase includes an oxide garnet phase. The cerium ion may be doped in the oxide garnet phase, and the oxide garnet phase may be Y3Al5O 12 (yttrium aluminate, abbreviated as YAG), Lu3Al5O12 (lutetium aluminum garnet, abbreviated as LuAG), Gd3(Al,Ga)5O 12 (cerium-doped gadolinium gallium aluminate, abbreviated as GAGG), etc., and the oxide garnet phase can be one or more of them.

[0052] In some embodiments, the molar doping concentration of the first luminescent ion is 0.01% to 10%, preferably 0.02% to 5%, which can serve as a fluorescence efficiency enhancement phase of the phosphor grain 10 or a color complementary phase of the phosphor grain 10; or / and the molar doping concentration of the second luminescent ion is 0.01% to 10%.

[0053] In some embodiments, the molar doping concentration of the first luminescent ion is less than the molar doping concentration of the second luminescent ion. Since the phosphor grains 10 are the main material for luminescence or light conversion, part of the excitation light needs to pass through the fluorescent grain boundary phase 30 to enter the phosphor grains 10. The doping concentration of the fluorescent grain boundary phase 30 generally cannot be higher than the doping concentration of the phosphor grains 10. If the molar doping concentration of the first luminescent ion is greater than or equal to the molar doping concentration of the second luminescent ion, it may be detrimental to the improvement of the overall luminous efficiency. The fluorescent grain boundary phase 30 only plays a role in supplementing or enhancing the luminescence of the phosphor grains 10.

[0054] In some embodiments, the volume content of the phosphor particles 10 in the luminescent ceramic is 10% to 90%, and may also be 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or any range between two of the above values. It should be noted that the volume content is the percentage of the phosphor particles 10 in the total volume of the luminescent ceramic. When the volume content of the phosphor particles 10 is within the range of 10% to 90%, high luminous intensity can be maintained. If the volume content of the phosphor particles 10 is less than 10%, fewer phosphor particles 10 are used for light conversion, and the overall luminous intensity of the luminescent ceramic is lower. If the volume content of the phosphor particles 10 is greater than 90%, the content of the matrix ceramic particles 20 used for heat conduction is lower, which is prone to thermal quenching of the luminescence, reducing the thermal saturation performance, and is also not conducive to improving the luminous intensity.

[0055] Optionally, the size of the phosphor particles 10 is 0.2 to 30 μm, and can further be 5 to 20 μm. The size of the phosphor particles 10 can also be set to 0.2 μm, 0.5 μm, 0.8 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 8 μm, 10 μm, 12 μm, 15 μm, 18 μm, 20 μm, 21 μm, 25 μm, 26 μm, 28 μm, 30 μm or a range between any two of the above values.

[0056] In some embodiments, the matrix ceramic grains 20 may be high thermal conductivity matrix ceramic grains 20. For example, the matrix ceramic grains 20 may include aluminum oxide (Al2O3), magnesium oxide (MgO), magnesium aluminate (MgAl2O4), boron nitride (BN), and aluminum nitride (AIN). The matrix ceramic grains 20 may be one or more of these.

[0057] The present application also proposes a method for preparing a luminescent ceramic, as shown in FIG4 , for preparing the luminescent ceramic of any of the above embodiments, the preparation method comprising:

[0058] Step S100: preparing fluorescent grain boundary phase raw materials, mixing, sintering and crushing the fluorescent grain boundary phase raw materials to obtain fluorescent grain boundary phase powder.

[0059] It can be understood that a fluorescent grain boundary phase raw material is prepared, wherein the fluorescent grain boundary phase raw material can be an oxide or nitrate, etc., and a ceramic precursor is synthesized by a solid phase method or a liquid phase method. The liquid phase method can, for example, use a co-precipitation process, a hydrothermal process or a sol-gel process to calcine the ceramic precursor at a low temperature to obtain a fluorescent grain boundary phase powder, and the fluorescent grain boundary phase powder is ground and sieved to obtain a fluorescent grain boundary phase powder with a uniform particle size distribution.

[0060] In one embodiment, as shown in FIG5 , the co-precipitation process includes:

[0061] Step S110: preparing a first mixed solution and a precipitant solution;

[0062] Step S120: adding the first mixed solution dropwise to the precipitant solution under stirring to form a precipitation solution containing precipitates;

[0063] Step S130: Separating a precipitate from the precipitate solution to obtain a ceramic precursor;

[0064] Step S140: calcining the ceramic precursor to obtain fluorescent grain boundary phase powder.

[0065] The first mixed solution can be obtained by dissolving the fluorescent grain boundary phase raw material in an acidic solution. The precipitant solution can contain an alkaline precipitant and a dispersant. The alkaline precipitant can be, for example, one or more of ammonia and ammonium bicarbonate, and the dispersant can be, for example, one or more of PEG, (NH4)2SO4, SDS, SDBS, etc. The calcination temperature can be, for example, 750-1000°C, and the calcination time can be 1-3 hours.

[0066] Step S200: preparing phosphor particles, matrix ceramic powder and sintering aids, mixing, calcining and molding the phosphor grain boundary phase powder, phosphor particles, matrix ceramic powder and sintering aids to obtain a ceramic body.

[0067] As shown in FIG6 , step S200 : preparing phosphor particles, matrix ceramic powder and sintering aids, mixing, calcining and molding the phosphor grain boundary phase powder, phosphor particles, matrix ceramic powder and sintering aids to obtain a ceramic body includes the following steps:

[0068] Step S210: ball-milling and wet-mixing the phosphor grain boundary phase powder, phosphor particles, matrix ceramic powder, and sintering aid to obtain a first slurry;

[0069] Step S220: drying, grinding and sieving the first slurry to obtain a mixed powder;

[0070] Step S230: calcining the mixed powder and pressing it into a shape to obtain a ceramic body.

[0071] It is understood that the ball milling wet mixing in step S100 can be performed using ethanol as the milling medium, using a ball mill. Forming can be performed, for example, by dry pressing or cold isostatic pressing. The dry pressing pressure can be 5-50 MPa, while the cold isostatic pressing pressure can be 50-250 MPa. Sintering aids can include one or more of calcium fluoride, magnesium oxide, calcium oxide, yttrium oxide, and silicon dioxide. Calcination can be performed at 750-1000°C for 1-3 hours.

[0072] Step S300: sintering the ceramic body to obtain a multi-phase luminescent ceramic block.

[0073] It can be understood that sintering can be carried out in a vacuum or inert protective atmosphere such as Ar gas, using a hot pressing sintering furnace or an SPS sintering furnace to sinter the ceramic body. The sintering temperature can be, for example, 1400-1800°C, the pressure can be 20-100 MPa, and the heat and pressure holding time can be 0.2-10 hours to obtain a luminescent ceramic block.

[0074] Step S400: annealing and surface treating the luminescent ceramic block to obtain luminescent ceramic.

[0075] It is understandable that the luminescent ceramic block is annealed and subjected to surface treatments such as grinding, polishing, and cutting in air to obtain the luminescent ceramic, wherein the annealing temperature can be, for example, 1000-1400° C. and the holding time can be 1-50 hours.

[0076] This application also provides a wavelength conversion device comprising a luminescent ceramic layer made of the luminescent ceramic of the above embodiment. The wavelength conversion device can be, for example, a fixed wavelength conversion device or a color wheel. Alternatively, the wavelength conversion device can be a reflective wavelength conversion device or a transmissive wavelength conversion device.

[0077] The present application also provides a light emitting device, comprising an excitation light source and a wavelength conversion device as described in the above embodiment. The light emitting device may include, for example, an illumination device, a projection device, an LD chip, or an LED chip.

[0078] The following describes the solution of this application with reference to specific embodiments:

[0079] Example 1

[0080] According to Y3Al5O 12 Nano-Al2O3, Y2O3, and CeO2 powders are weighed in a stoichiometric ratio of 1:1:Ce, wherein the molar doping concentration of Ce is 0.2%. The Al2O3, Y2O3, and CeO2 powders are dissolved in an acidic solution to obtain a first mixed solution. A precipitant solution containing PEG and ammonia is prepared. Under stirring conditions, the first mixed solution is added dropwise to the precipitant solution to form a precipitate containing a precipitate. The precipitate is filtered and separated from the precipitate, and dried to obtain a ceramic precursor. The ceramic precursor is calcined at 800°C for 2 hours to obtain a fluorescent grain boundary phase powder. Y3Al5O with a particle size of 5 μm is prepared. 12 Ce phosphor powder, with a molar Ce doping concentration of 0.5%, is prepared. Alumina powder with a particle size of 1μm is prepared, and tetraethyl orthosilicate is used as a sintering aid, with the sintering aid accounting for 1% of the total powder weight. The mass ratio of alumina powder to phosphor particles is 9:1, and the mass of the phosphor grain boundary phase powder is 5% of the phosphor particle mass. The phosphor grain boundary phase powder, alumina powder, and sintering aid are ball-milled using ethanol as a medium at 200 rpm for 4 hours to obtain a first slurry. The first slurry is then dried, ground, and sieved to obtain a mixed powder. The mixed powder is calcined at 800°C for 2 hours to remove organic additives and impurities, and then dry-pressed at 20 MPa to obtain a ceramic body. Sintering can be performed in a hot-pressing furnace under vacuum at a sintering temperature of 1400°C, a pressure of 20 MPa, and a holding time of 3 hours to obtain a luminescent ceramic block. The luminescent ceramic block is subjected to annealing and surface treatment such as grinding, polishing, and cutting in air to obtain the luminescent ceramic, wherein the annealing temperature is 1000° C. and the temperature is kept for 30 hours.

[0081] Example 2

[0082] According to Y3Al5O 12Nano-Al2O3, Y2O3, and CeO2 powders are weighed in a stoichiometric ratio of 0.2% Ce:Ce, wherein the molar doping concentration of Ce is 0.2%. The Al2O3, Y2O3, and CeO2 powders are dissolved in an acidic solution to obtain a first mixed solution. A precipitant solution containing PEG and ammonia is prepared. Under stirring conditions, the first mixed solution is added dropwise to the precipitant solution to form a precipitate containing a precipitate. The precipitate is filtered and separated from the precipitate, and dried to obtain a ceramic precursor. The ceramic precursor is calcined at 800°C for 2 hours to obtain a fluorescent grain boundary phase powder. Y3Al5O with a particle size of 10 μm is prepared. 12 Ce phosphor, with a molar Ce doping concentration of 0.5%, is prepared. Alumina powder with a particle size of 1μm is prepared, and tetraethyl orthosilicate is used as a sintering aid, with the sintering aid accounting for 1% of the total powder weight. The mass ratio of alumina powder to phosphor particles is 6:4, and the mass of the phosphor grain boundary phase powder is 10% of the phosphor particle mass. The phosphor grain boundary phase powder, alumina powder, and sintering aid are ball-milled using ethanol as a medium at 200 rpm for 4 hours to obtain a first slurry. The first slurry is dried, ground, and sieved to obtain a mixed powder. The mixed powder is calcined at 800°C for 2 hours to remove organic additives or impurities, and then dry-pressed at 20 MPa to obtain a ceramic body. Sintering can be performed in a hot-pressing furnace under vacuum at a sintering temperature of 1600°C, a pressure of 50 MPa, and a holding time of 3 hours to obtain a luminescent ceramic block. The luminescent ceramic block is subjected to annealing and surface treatment such as grinding, polishing, and cutting in air to obtain the luminescent ceramic, wherein the annealing temperature is 1200° C. and the temperature is kept for 20 hours.

[0083] Example 3

[0084] According to Y3Al5O 12 Nano-Al2O3, Y2O3, and CeO2 powders are weighed in a stoichiometric ratio of 1:10, wherein the molar doping concentration of Ce is 0.2%. The Al2O3, Y2O3, and CeO2 powders are dissolved in an acidic solution to obtain a first mixed solution. A precipitant solution containing PEG and ammonia is prepared. Under stirring conditions, the first mixed solution is added dropwise to the precipitant solution to form a precipitate containing a precipitate. The precipitate is filtered and separated from the precipitate, and dried to obtain a ceramic precursor. The ceramic precursor is calcined at 800°C for 2 hours to obtain a fluorescent grain boundary phase powder. Y3Al5O with a particle size of 20 μm is prepared. 12Ce phosphor powder, with a molar Ce doping concentration of 0.5%, is prepared. Alumina powder with a particle size of 1μm is prepared, and tetraethyl orthosilicate is used as a sintering aid, with the sintering aid accounting for 1% of the total powder weight. The mass ratio of alumina powder to phosphor particles is 1:9, and the mass of the phosphor grain boundary phase powder is 20% of the phosphor particle mass. The phosphor grain boundary phase powder, alumina powder, and sintering aid are ball-milled using ethanol as a medium at 200 rpm for 4 hours to obtain a first slurry. The first slurry is dried, ground, and sieved to obtain a mixed powder. The mixed powder is calcined at 800°C for 2 hours to remove organic additives and impurities, and then dry-pressed at 20 MPa to obtain a ceramic body. Sintering can be performed in a hot-pressing furnace under vacuum at a sintering temperature of 1700°C, a pressure of 100 MPa, and a holding time of 10 hours to obtain a luminescent ceramic block. The luminescent ceramic block is subjected to annealing and surface treatment such as grinding, polishing, and cutting in air to obtain the luminescent ceramic, wherein the annealing temperature is 1400° C. and the temperature is kept for 10 hours.

[0085] Example 4

[0086] According to Y3Al5O 12 Nano-Al2O3, Y2O3, and CeO2 powders are weighed in a stoichiometric ratio of 1:10, wherein the molar doping concentration of Ce is 0.5%. The Al2O3, Y2O3, and CeO2 powders are dissolved in an acidic solution to obtain a first mixed solution. A precipitant solution containing PEG and ammonia is prepared. Under stirring conditions, the first mixed solution is added dropwise to the precipitant solution to form a precipitate containing a precipitate. The precipitate is filtered and separated from the precipitate, and dried to obtain a ceramic precursor. The ceramic precursor is calcined at 800°C for 2 hours to obtain a fluorescent grain boundary phase powder. Y3Al5O with a particle size of 10 μm is prepared. 12 Ce phosphor, with a molar Ce doping concentration of 0.5%, is prepared. Alumina powder with a particle size of 1μm is prepared, and tetraethyl orthosilicate is used as a sintering aid, with the sintering aid accounting for 1% of the total powder weight. The mass ratio of alumina powder to phosphor particles is 6:4, and the mass of the phosphor grain boundary phase powder is 10% of the phosphor particle mass. The phosphor grain boundary phase powder, alumina powder, and sintering aid are ball-milled using ethanol as a medium at 200 rpm for 4 hours to obtain a first slurry. The first slurry is dried, ground, and sieved to obtain a mixed powder. The mixed powder is calcined at 800°C for 2 hours to remove organic additives or impurities, and then dry-pressed at 20 MPa to obtain a ceramic body. Sintering can be performed in a hot-pressing furnace under vacuum at a sintering temperature of 1600°C, a pressure of 50 MPa, and a holding time of 3 hours to obtain a luminescent ceramic block. The luminescent ceramic block is subjected to annealing and surface treatment such as grinding, polishing, and cutting in air to obtain the luminescent ceramic, wherein the annealing temperature is 1200° C. and the temperature is kept for 20 hours.

[0087] Example 5

[0088] According to Lu3Al5O 12 Nano-Al2O3, Lu2O3, and CeO2 powders were weighed in a stoichiometric ratio of 1:1:1 Ce, wherein the molar doping concentration of Ce was 0.2%. The Al2O3, Lu2O3, and CeO2 powders were dissolved in an acidic solution to obtain a first mixed solution. A precipitant solution containing PEG and ammonia was prepared. The first mixed solution was added dropwise to the precipitant solution under stirring to form a precipitate containing a precipitate. The precipitate was filtered and separated from the precipitate, and dried to obtain a ceramic precursor. The ceramic precursor was calcined at 800°C for 2 hours to obtain a fluorescent grain boundary phase powder. Y3Al5O with a particle size of 5 μm was prepared. 12 Ce phosphor, with a molar Ce doping concentration of 0.5%, is prepared. Alumina powder with a particle size of 1μm is prepared, and tetraethyl orthosilicate is used as a sintering aid, with the sintering aid accounting for 1% of the total powder weight. The mass ratio of alumina powder to phosphor particles is 6:4, and the mass of the phosphor grain boundary phase powder is 10% of the phosphor particle mass. The phosphor grain boundary phase powder, alumina powder, and sintering aid are ball-milled using ethanol as a medium at 200 rpm for 4 hours to obtain a first slurry. The first slurry is dried, ground, and sieved to obtain a mixed powder. The mixed powder is calcined at 800°C for 2 hours to remove organic additives or impurities, and then dry-pressed at 20 MPa to obtain a ceramic body. Sintering can be performed in a hot-pressing furnace under vacuum at a sintering temperature of 1600°C, a pressure of 50 MPa, and a holding time of 3 hours to obtain a luminescent ceramic block. The luminescent ceramic block is subjected to annealing and surface treatment such as grinding, polishing, and cutting in air to obtain the luminescent ceramic, wherein the annealing temperature is 1200° C. and the temperature is kept for 20 hours.

[0089] It should be noted that the various optional implementation methods introduced in the embodiments of the present application can be implemented in combination with each other or can be implemented separately, and the embodiments of the present application do not limit this.

[0090] In the description of this application, it should be understood that the terms "upper", "lower", "left", "right", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, and a specific orientation structure and operation. Therefore, it cannot be understood as a limitation on this application. In addition, "first" and "second" are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise specified, "multiple" means two or more.

[0091] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0092] The above embodiments are described with reference to the accompanying drawings. Other different forms and embodiments are also possible without departing from the principles of the present application, and therefore the present application should not be construed as limiting the embodiments presented herein. Rather, these embodiments are provided so that the present application will be perfect and complete, and will convey the scope of the present application to those skilled in the art. In the accompanying drawings, component sizes and relative sizes may be exaggerated for clarity. The terms used herein are for the purpose of describing specific embodiments only and are not intended to be limiting. The terms "comprising" and / or "including" when used in this specification indicate the presence of the features, integers, components and / or components, but do not exclude the presence or increase of one or more other feature integers, components, components and / or their groups. Unless otherwise indicated, when stated, a numerical range includes the upper and lower limits of the range and any sub-ranges therebetween.

[0093] The above descriptions are only some embodiments of the present application and do not limit the scope of protection of the present application. Any equivalent device or equivalent process transformation made using the contents of the description and drawings of this application, or directly or indirectly applied in other related technical fields, are also included in the scope of patent protection of this application.

Claims

1. A luminescent ceramic, characterized in that: It comprises phosphor crystal grains, matrix ceramic crystal grains and phosphor grain boundary phases, wherein the phosphor grain boundary phases are located between the matrix ceramic crystal grains or / and between the matrix ceramic crystal grains and the phosphor crystal grains.

2. The luminescent ceramic according to claim 1, characterized in that: The fluorescent grain boundary phase includes at least one of a first fluorescent grain boundary phase, a second fluorescent grain boundary phase and a third fluorescent grain boundary phase; The first fluorescent grain boundary phase is located between the matrix ceramic grains, the second fluorescent grain boundary phase is arranged between the matrix ceramic grains and the fluorescent powder grains, and the third fluorescent grain boundary phase is enclosed in the periphery of the fluorescent powder grains.

3. The luminescent ceramic according to claim 1 or 2, characterized in that: The fluorescent grain boundary phase accounts for 5% to 20% of the total volume of the luminescent ceramic.

4. The luminescent ceramic according to claim 3, characterized in that: The first fluorescent grain boundary phase accounts for 5% to 40% of the total volume of the grain boundary phase; or / and the second fluorescent grain boundary phase accounts for 5% to 40% of the total volume of the grain boundary phase; Or / and the third fluorescent grain boundary phase accounts for 5% to 40% of the total volume of the grain boundary phase.

5. The luminescent ceramic according to claim 1, characterized in that: The fluorescent grain boundary phase includes a first matrix phase doped with a first luminescent ion; The phosphor crystal grains include a second matrix phase doped with a second luminescent ion; The first luminescent ion is the same as or different from the second luminescent ion; Or / and the first matrix phase is the same as or different from the second matrix phase.

6. The luminescent ceramic according to claim 5, characterized in that: The first matrix phase and the second matrix phase are oxide garnet phases; the first luminescent ions and the second luminescent ions are cerium ions.

7. The luminescent ceramic according to claim 5 or 6, characterized in that: The molar doping concentration of the first luminescent ions is 0.02% to 5%; or / and the molar doping concentration of the second luminescent ions is 0.01% to 10%.

8. The luminescent ceramic according to claim 7, characterized in that: The molar doping concentration of the first light-emitting ions is less than the molar doping concentration of the second light-emitting ions.

9. The luminescent ceramic according to claim 1, characterized in that: The volume content of the phosphor particles is 10% to 90%; Or / and the size of the phosphor grains is 5-20 μm.

10. A method for preparing a luminescent ceramic, characterized in that: The preparation method comprises: preparing fluorescent grain boundary phase raw materials, mixing, sintering and crushing the fluorescent grain boundary phase raw materials to obtain fluorescent grain boundary phase powder; Preparing phosphor particles, matrix ceramic powder and sintering aid, mixing, calcining and molding the phosphor grain boundary phase powder, phosphor particles, matrix ceramic powder and sintering aid to obtain a ceramic body; Sintering the ceramic body to obtain a luminescent ceramic block; The luminescent ceramic block is annealed and surface treated to obtain the luminescent ceramic.

11. A wavelength conversion device, characterized in that: The invention comprises a luminescent ceramic layer, wherein the luminescent ceramic layer is made of the luminescent ceramic according to any one of claims 1 to 9.

12. A light emitting device, characterized in that: It comprises an excitation light source and the wavelength conversion device as claimed in claim 11.

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