All-spectrum complex-phase fluorescent ceramic and preparation method and application thereof

Abstract

The application provides a full-spectrum complex-phase fluorescent ceramic and a preparation method and application thereof. 1‑x‑y Sr y AlSiN3:xEu (0 1‑x‑a‑b Y a Gd b )3(Al 1‑c Ga c )5O 12 :xCe (0 12 The short-time ceramic sintering and the faster temperature rising and falling rate in the application effectively slow down the grain growth in the ceramic sintering process, and in the short-time sintering process, the nitride powder forms the oxide phase in situ without causing large decomposition or sintering so as to make it invalid. In short, through the short-time high-temperature pulse sintering, the sintering densification of the complex-phase ceramic is promoted, and the nitride phase is avoided from being oxidized in the long-time high-temperature process to cause the sharp drop of the luminous efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of fluorescent materials, and specifically relates to a full-spectrum composite fluorescent ceramic, a preparation method thereof, and an application thereof. Background Art

[0002] White light sources constructed with ultra-high brightness lasers as excitation light sources have good light output directivity and a more compact structure, which have attracted wide attention in the industry and the related technologies have developed rapidly. Shuji Nakamura, the Nobel laureate in physics and the inventor of blue LEDs, pointed out that "in the future, laser lighting may replace LED lighting". High energy density lasers as excitation light sources pose stringent requirements on the structural stability, thermal conductivity, radiation resistance, etc. of fluorescence conversion materials. The traditional technology of encapsulating fluorescent powders with silicone rubber will be phased out (silicone rubber is extremely easy to be carbonized under high energy density laser irradiation), and developing all-inorganic fluorescent bulk materials will be the only choice.

[0003] As shown Figure 3 , the traditional technology of encapsulating fluorescent powders with silicone rubber is prone to carbonization failure under the irradiation of high power density light sources, and there is an urgent need to develop a new generation of all-inorganic fluorescence conversion materials. By sintering fluorescent powders into fluorescent ceramics at high temperature, it has advantages such as high temperature resistance and high reliability. Therefore, all-inorganic fluorescent ceramics have become ideal new generation light conversion materials and are also a new research direction in the field of supporting materials for the semiconductor lighting and display industries.

[0004] If a garnet structure compound ((Lu 1-x-a-b Y a Gd b )3(Al 1-c Ga c )5O 12 :xCe(0 < x ≤ 0.06, 0 ≤ a < 1, 0 ≤ b < 1, 0 ≤ c < 1, 0 ≤ a + b < 1)) and a nitride (Ca 1-x-y Sr y AlSiN3:xEu(0 < x ≤ 0.03, 0 < y ≤ 1)) are used to achieve the sintering preparation of an integrated composite fluorescent ceramic and obtain a full-spectrum fluorescent ceramic with high reliability, then it will meet the development needs of the new generation of semiconductor lighting and display industries. However, in the traditional sintering method, during the high-temperature and long-time sintering process, the nitride will be severely oxidized, resulting in a sharp decline in luminous efficiency. Even when using a faster spark plasma sintering, the sintering time is sufficient for the reaction between the nitride and the oxide. Therefore, a faster sintering method needs to be found to avoid the reaction between the two.

[0005] Patent document CN115490508A discloses a composite fluorescent ceramic for white light LD lighting. The composite fluorescent ceramic is composed of an oxide ceramic layer from bottom to top ((Y3-□x Ce x )3Al5O 12 , 0.001 ≤ x ≤ 0.01), a nitrogen oxide ceramic layer (Si 6-y Al y O y N 8-y :Eu 2+ , 0.2 ≤ y ≤ 2) and a nitride ceramic layer (CaAlSiN3:Eu 2+ ), are formed layer by layer by the tape casting method and further sintered. This solution provides a method for preparing a full-spectrum composite ceramic, but its preparation process is complex, and the laminated structure may be unfavorable for the propagation of the light path.

[0006] Patent document CN111285682A discloses a full-spectrum composite fluorescent ceramic for laser lighting and display and a preparation method thereof, adopting a solution of preparing a full-spectrum composite fluorescent ceramic by combining two phases. In this solution, both phases are garnet-structured oxides, and the spectrum of the composite fluorescent ceramic formed by them is not completely covered in the full-spectrum band due to the limitation of the spectra of the phases of its composition components. Summary of the Invention

[0007] The object of the present invention is to overcome the above deficiencies of the prior art and provide a full-spectrum composite fluorescent ceramic, its preparation method and application.

[0008] To achieve the above object of the invention, in the first aspect, the present invention provides a full-spectrum composite fluorescent ceramic, which is composed of a nitride phase and an oxide phase. The chemical composition of the nitride phase is Ca 1-x- y Sr y AlSiN3:xEu(0 < x ≤ 0.03, 0 < y ≤ 1), and its crystal structure is the same as that of CaAlSiN3; the chemical composition of the oxide phase is (Lu 1-x-a-b Y a Gd b )3(Al 1-c Ga c )5O 12 :xCe(0 < x ≤ 0.06, 0 ≤ a < 1, 0 ≤ b < 1, 0 ≤ c < 1, 0 ≤ a + b < 1), and its crystal structure is the same as that of Lu3Al5O 12 the same.

[0009] In one embodiment, the weight ratio of the nitride phase to the oxide phase in the composite fluorescent ceramic is 1:5 to 1:15.

[0010] In one embodiment, in the nitride phase, x = 0.008 and y = 0; in the oxide phase, x = 0.01, a = b = c = 0.

[0011] In one embodiment, the composite fluorescent ceramic can emit fluorescence with wavelengths covering the range of 480 - 780 nanometers under the excitation of a blue light source.

[0012] Second, the present invention provides a method for preparing a full-spectrum composite fluorescent ceramic, including:

[0013] Preparing nitride-phase powder;

[0014] Weigh and mix high-purity Lu2O3 powder, Y2O3 powder, Gd2O3 powder, Al2O3 powder, Ga2O3 powder, CeO2 powder and nitride-phase powder according to the weight ratios of different nitride phases and oxide phases to obtain a raw material mixture; put the raw material mixture into a mortar, and sequentially add a dispersant, a flux, and alcohol thereto, and grind to make the raw materials evenly mixed to obtain a raw material mixture;

[0015] Dry-press the raw material mixture into a block-shaped green body of the composite fluorescent ceramic;

[0016] Put the obtained block-shaped green body of the composite fluorescent ceramic into a muffle furnace for debinding, then after cold isostatic pressing, perform in-situ rapid sintering in a vacuum Joule-heating furnace to obtain the full-spectrum composite fluorescent ceramic.

[0017] In one embodiment, preparing the nitride-phase powder includes:

[0018] Using high-purity Ca3N2, Sr3N2, AlN, Si3N4 and EuN as raw material powders, according to the composition general formula Ca 1-x-y Sr y AlSiN3:xEu (0 < x ≤ 0.03, 0 < y ≤ 1), weigh and mix in a glove box to obtain a raw material mixed powder, put the obtained raw material mixed powder into a high-purity boron nitride crucible, then put it into a gas pressure furnace, the sintering temperature is 1600 - 1800 degrees Celsius, the nitrogen pressure is 0.9 MPa, the heat preservation time is 4 - 10 hours, and after cooling, obtain Ca 1-x-y Sr y AlSiN3:xEu red phosphor, that is, the nitride-phase powder.

[0019] In one embodiment, the preparation method of Lu2O3 powder includes:

[0020] Dissolve 6 - 10 grams of Lu2O3 micron powder in 20 milliliters of nitric acid, react in a reaction kettle at 80 degrees Celsius for 24 hours, then add 8 - 12 milliliters of supersaturated ammonium bicarbonate solution, react for 4 hours with stirring, take it out and centrifuge 3 - 5 times with ionized water or ethanol, then put it into an oven at 80 degrees Celsius to dry, take it out and grind, then transfer it into a muffle furnace and calcine at 900 degrees Celsius for 2 hours to obtain Lu2O3 powder.

[0021] In one embodiment, the dispersant is ammonium citrate, with an addition amount of 1-5 wt.%, the flux is tetraethyl orthosilicate, with an addition amount of 0.1-1 wt.%, and the amount of alcohol added is 5-6 ml; the pressure for dry pressing is 20-60 kN, and the holding time is 2-6 minutes.

[0022] In one embodiment, the debinding conditions in the muffle furnace are 550 degrees Celsius and the debinding time is 12 to 16 hours; the cold isostatic pressing pressure is 250 MPa and the holding time is 180 seconds; in-situ rapid sintering is performed, with the ceramic green body fixed by the sintering medium, the sintering temperature is 1500 to 1700 degrees Celsius, the sintering time is 8 to 20 seconds, and the environment is a nitrogen protective atmosphere or a vacuum environment with a vacuum degree not exceeding 0.001 Pa.

[0023] Thirdly, this invention provides an application of full-spectrum multiphase fluorescent ceramics in the field of laser lighting.

[0024] The advantages and beneficial effects of this invention compared to the prior art are as follows:

[0025] (1) In this invention, the short ceramic sintering time and the rapid heating and cooling rates effectively slow down grain growth during the ceramic sintering process. Furthermore, during the short sintering process, the nitride powder forms an oxide phase in situ without undergoing significant decomposition or sintering, thus preventing its failure. In short, short-duration high-temperature pulse sintering promotes the dense sintering of the multiphase ceramic while avoiding the sharp drop in luminous efficiency caused by the oxidation of the nitride phase during prolonged high-temperature processes.

[0026] (2) By adjusting the ratio of red luminescent material to green luminescent material, a multiphase fluorescent ceramic with a full-spectrum tunable fluorescence range of 480–780 nm is achieved, thereby realizing a multiphase fluorescent ceramic with a high color rendering index (CRI), with a maximum CRI exceeding 90 and reaching 92. The prepared nano-fluorescent ceramic has many advantages, such as being effectively excited by ultraviolet or blue light sources, having tunable color, and long lifespan. It is expected that the integrated full-spectrum fluorescent ceramic and its preparation method of this invention will be widely used and developed in the field of laser lighting.

[0027] (3) In this invention, a Joule heating device is used to prepare full-spectrum multiphase fluorescent ceramics, and the oxide phase of this part is sintered in situ, which is simple to operate and fast to prepare. The sintering time of this method is reduced from tens of hours in the traditional method to seconds, which successfully saves energy consumption in the preparation process and reduces the time and energy costs of multiphase fluorescent ceramic production. Attached Figure Description

[0028] Figure 1 This is a schematic diagram illustrating the Joule heating sintering principle of ceramics according to the present invention;

[0029] Figure 2 is Ca 0.992 Schematic diagram of the coating of CaAlSiN3:0.008Eu powder

[0030] Figure 3 Schematic diagram of the encapsulation of traditional light conversion materials and the structure diagram and optical path diagram of the prepared composite fluorescent ceramics

[0031] Figure 4 Spectral diagram of the composite fluorescent ceramics prepared at different sintering temperatures in Example 1

[0032] Figure 5 SEM image of the composite fluorescent ceramics prepared in Example 2 under the conditions of a sintering temperature of 1625 °C and a time of 9 - 13 s

[0033] Figure 6 XRD pattern of the composite fluorescent ceramics prepared in Example 3 under the conditions of a sintering temperature of 1625 °C, a sintering time of 10 s, and a weight ratio of nitride phase to oxide phase of 1:5 - 1:15

[0034] Figure 7 Spectral diagram of the composite fluorescent ceramics prepared in Example 3 under the conditions of a sintering temperature of 1625 °C, a sintering time of 10 s, and a weight ratio of nitride phase to oxide phase of 1:5 - 1:15

[0035] Figure 8 Chromaticity coordinate diagram of the composite fluorescent ceramics prepared in Example 3 under the conditions of a sintering temperature of 1625 °C, a sintering time of 10 s, and a weight ratio of nitride phase to oxide phase of 1:5 - 1:15 Detailed implementation manners

[0036] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention

[0037] In the first aspect, the present invention provides a full - spectrum composite fluorescent ceramic, which is composed of a nitride phase and an oxide phase. The chemical composition of the nitride phase is Ca 1-x-y Sr y AlSiN3:xEu(0 < x ≤ 0.03, 0 < y ≤ 1), and its crystal structure is the same as that of CaAlSiN3; the chemical composition of the oxide phase is (Lu 1-x-a-b Y a Gd b )3(Al 1-c Ga c )5O12 : xCe (0 < x ≤ 0.06, 0 ≤ a < 1, 0 ≤ b < 1, 0 ≤ c < 1, 0 ≤ a + b < 1), and its crystal structure is the same as that of Lu3Al5O 12 .

[0038] Within these numerical ranges, red and green fluorescent materials with good performance and satisfying the emission band can be prepared.

[0039] Among them, when the oxide phase is Lu3Al5O 12 :Ce 3+ , Lu3Al5O 12 :Ce 3+ is formed in-situ. In Lu3Al5O 12 :Ce 3+ , Ce 3+ acts as the luminescence center and activator, and the doping ratio is 0.6 at.%. The crystallization of Lu3Al5O 12 :Ce 3+ forms in a pure phase, and its crystalline phase is formed in a dense block manner. In the structure of the composite fluorescent ceramic, when the nitride phase is CaAlSiN3:Eu 2 + , the formed Lu3Al5O 12 :Ce 3+ and CaAlSiN3:Eu 2+ powder can contact each other to form a relatively dense structure.

[0040] Among them, the prepared nitride phase is fired at high temperature under high nitrogen pressure in a gas pressure furnace. The oxide phase is formed in-situ during the ceramic sintering process. After crystallization, it can form a pure phase and is formed in a dense block manner. The luminescence center and activator in this luminescent phase are cerium ions (Ce 3+ ), and the doping ratio is 0 - 0.06 (at.).

[0041] Furthermore, in the nitride phase, x = 0.008, y = 0; in the oxide phase, x = 0.01, a = b = c = 0. That is, the preferred value in the nitride is x = 0.008, y = 0. The preferred value in the oxide is x = 0.01, a = b = c = 0. The composite fluorescent ceramic prepared at this time can cover a wider emission band, and its efficiency is high, and the color rendering index can be greater than 90, up to 92 at most. Under the preferred conditions:

[0042] When the weight ratio of the nitride phase to the oxide phase is 1:3 - 1:5 and more than 1:15, the sintering temperature is 1500 - 1700 degrees Celsius, and the sintering time is 8 - 20 seconds, the obtained color rendering index ≤ 70.

[0043] When the weight ratio of nitride phase to oxide phase is 1:7 and 1:13, the sintering temperature is 1500-1700 degrees Celsius, and the sintering time is 8-20 seconds, the obtained color index is 75-78.

[0044] When the weight ratio of nitride phase to oxide phase is 1:9 to 1:11, the sintering temperature is 1500 to 1700 degrees Celsius, and the sintering time is 8 to 20 seconds, the obtained color index is ≥88.

[0045] Furthermore, the weight ratio of the nitride phase to the oxide phase in the multiphase fluorescent ceramic is 1:5 to 1:15. Within this weight ratio range, multiphase fluorescent ceramics with tunable emission colors ranging from red to yellow-green can be prepared. Preferably, when the weight ratio of the nitride phase to the oxide phase is 1:9 to 1:11, the color rendering index of the obtained multiphase fluorescent ceramic reaches its highest value, and the color rendering index of multiphase fluorescent ceramics prepared within this range is ≥88.

[0046] Furthermore, when excited by a blue light source (wavelength 440–470 nm), the multiphase fluorescent ceramic can emit fluorescence with a wavelength range covering 480–780 nm.

[0047] By adjusting the ratio of nitride phase (red fluorescent phase) to oxide phase (green fluorescent phase), a full-spectrum tunable fluorescent ceramic with fluorescence in the range of 480–780 nm can be realized. Furthermore, the emission spectrum can be wide-range tuned in the visible light region, and multiphase fluorescent ceramics with high color rendering index can be further realized.

[0048] Secondly, this invention also proposes a method for preparing full-spectrum multiphase fluorescent ceramics, which can synthesize multiphase fluorescent ceramics in situ. Using a Joule-heated pulsed Joule heating device, the temperature is raised to 1500–1700 degrees Celsius in a very short time by utilizing the Joule effect, as shown in the schematic diagram below. Figure 1 As shown. The multiphase fluorescent ceramics prepared by this method do not require further heat treatment or other processes. Through 10... 5 A heating / cooling rate of degrees Celsius per second, at 1500–1700 degrees Celsius, with pulse heating for less than 20 seconds, under a nitrogen protective atmosphere or a vacuum environment with a vacuum degree not exceeding 0.001 Pa, allows for the direct one-step synthesis of full-spectrum multiphase fluorescent ceramics consisting of nitrides and oxides. Specific steps include:

[0049] Step S1: Prepare nitride phase powder;

[0050] Step S2: Weigh and mix high-purity Lu2O3 powder, Y2O3 powder, Gd2O3 powder, Al2O3 powder, Ga2O3 powder, CeO2 powder and nitride-phase powder according to the weight ratios of different nitride phases and oxide phases to obtain a raw material mixture. Put the raw material mixture into a mortar, and successively add a dispersant, a flux and alcohol thereto, and grind to make the raw materials evenly mixed to obtain the raw material mixture.

[0051] Among them, high purity means a purity of more than 99.99%; meanwhile, the Lu2O3 powder is prepared by oneself, and in addition, the Y2O3 powder, Gd2O3 powder, Al2O3 powder, Ga2O3 powder and CeO2 powder are all commercial powders.

[0052] Step S3: Carry out dry pressing on the raw material mixture to obtain a bulk ceramic green body of a composite-phase fluorescent ceramic.

[0053] Step S4: Put the obtained bulk ceramic green body of the composite-phase fluorescent ceramic into a muffle furnace for degumming, then after cold isostatic pressing, carry out in-situ rapid sintering in a vacuum Joule-heating furnace to prepare a full-spectrum composite-phase fluorescent ceramic.

[0054] Further, the preparation of the nitride-phase powder includes:

[0055] Using high-purity Ca3N2, Sr3N2, AlN, Si3N4 and EuN as raw material powders, according to the composition general formula Ca 1-x-y Sr y AlSiN3:xEu (0 < x ≤ 0.03, 0 < y ≤ 1), carry out weighing and mixing in a glove box to obtain a raw material mixed powder. Put the obtained raw material mixed powder into a high-purity boron nitride crucible, and then put it into a gas pressure furnace. The sintering temperature is 1600 - 1800 °C, the nitrogen pressure is 0.9 MPa, and the heat preservation time is 4 - 10 hours. After cooling, obtain Ca 1-x-y Sr y AlSiN3:xEu red phosphor, that is, the nitride-phase powder.

[0056] Further, the preparation method of the Lu2O3 powder includes:

[0057] Dissolve 6 - 10 g of Lu2O3 fine powder in 20 ml of nitric acid, react in a reaction kettle at 80 °C for 24 hours, then add 8 - 12 ml of supersaturated ammonium bicarbonate solution, react for 4 hours with stirring, take out and centrifuge 3 - 5 times with ionized water or ethanol, then put it into an oven at 80 °C for drying, take out and grind, and then transfer it into a muffle furnace and calcine at 900 °C for 2 hours to obtain Lu2O3 powder. Among them, the preferred addition amount of Lu2O3 is 8 g, and the preferred addition amount of the supersaturated ammonium bicarbonate solution is 10 ml.

[0058] Furthermore, the dispersant is ammonium citrate, with an addition dosage of 1–5 wt.%, the flux is tetraethyl orthosilicate, with an addition dosage of 0.1–1 wt.%, and the amount of alcohol added is 5–6 ml; the pressure for dry pressing is 20–60 kN, and the holding time is 2–6 minutes.

[0059] Furthermore, the debinding conditions in the muffle furnace are 550 degrees Celsius for 12–16 hours; cold isostatic pressing pressure is 250 MPa for 180 seconds; in-situ rapid sintering is performed, with the ceramic green body fixed by carbon cloth as the sintering medium, at a sintering temperature of 1500–1700 degrees Celsius for 8–20 seconds, under a nitrogen protective atmosphere or a vacuum environment with a vacuum degree not exceeding 0.001 Pa. Under these conditions, ceramics with good density and high luminous efficiency can be synthesized.

[0060] Preferably, the dispersant dosage is 2 wt.% and the flux dosage is 1 wt.%; the dry pressing pressure is 40 kN and the holding time is 3 minutes; the glue removal time is 12 hours; the sintering temperature is 1650 degrees Celsius and the sintering time in a nitrogen atmosphere is 10 seconds.

[0061] Thirdly, this invention provides an application of full-spectrum multiphase fluorescent ceramics in the field of laser lighting.

[0062] This invention has undergone numerous experiments, and some of the experimental results are presented here for reference to further describe the invention in detail. The following is a detailed description in conjunction with specific embodiments.

[0063] Example 1

[0064] A method for preparing full-spectrum multiphase fluorescent ceramics, comprising:

[0065] Step 1: Preparation of nitride phase powder

[0066] Using high-purity Ca3N2, AlN, Si3N4, and EuN as raw material powders, according to the general formula Ca 0.992 AlSiN3:0.008Eu was weighed and mixed in a glove box to obtain a raw material mixture powder. The obtained raw material mixture powder was placed in a high-purity boron nitride crucible, and then placed in a pressure furnace. The sintering temperature was 1750 degrees Celsius, the nitrogen pressure was 0.9 MPa, and the holding time was 8 hours. After cooling, Ca was obtained. 0.992 AlSiN3:0.008Eu red phosphor, i.e. nitride phase powder;

[0067] Step 2: Preparation of Lu2O3 powder

[0068] 8 g of Lu2O3 micron powder was dissolved in 20 mL of nitric acid and reacted in a reactor at 80°C for 24 hours. Then, 10 mL of supersaturated ammonium bicarbonate solution was added, and the reaction was continued for 4 hours with stirring. After removal, the powder was centrifuged 5 times with deionized water and then dried in an oven at 80°C. After grinding, the powder was transferred to a muffle furnace and calcined at 900°C for 2 hours to obtain Lu2O3 powder.

[0069] Step 3: Prepare the raw material mixture

[0070] High-purity Lu2O3 powder, Y2O3 powder, Gd2O3 powder, Al2O3 powder, Ga2O3 powder, CeO2 powder, and nitride phase powder, with a nitride phase to oxide phase weight ratio of 1:9, were weighed and mixed to obtain a raw material mixture. The raw material mixture was then placed in a mortar, and 2 wt.% ammonium citrate, 1 wt.% tetraethyl orthosilicate, and 6 ml of alcohol were added sequentially. The mixture was then ground until homogeneous to obtain the raw material mixture.

[0071] Step 4: Preparation of multiphase fluorescent ceramic bulk green bodies

[0072] Weigh 0.16 g of raw material mixture, put it into a 10 mm diameter mold, and hold it under a pressure of 40 kN for 3 minutes to obtain fluorescent ceramic green body. Then, transfer it to a muffle furnace at 550 degrees Celsius for 12 hours to remove the binder. After the binder is removed, cold isostatic pressing is performed under a pressure of 250 MPa for 3 minutes to finally obtain multiphase fluorescent ceramic block green body.

[0073] Step 5: Sintering

[0074] Multiphase fluorescent ceramic bulk green bodies were sintered in a nitrogen atmosphere using pulsed Joule heating sintering at a temperature of 1600–1675 degrees Celsius for 10 seconds, producing full-spectrum multiphase fluorescent ceramics.

[0075] Its spectrum is as follows Figure 4 It can be seen that when the sintering temperature is around 1650 degrees Celsius, its spectrum can better cover the range of 480 to 780 nanometers, and its green spectrum is better.

[0076] Example 2

[0077] The difference from Example 1 is that the sintering temperature is 1625 degrees Celsius and the time is 9 to 13 seconds.

[0078] Its electron microscope image is as follows Figure 5 As shown, the porosity within the ceramic is minimized when the sintering time is 10 seconds. Among all sintered multiphase fluorescent ceramics, the red-emitting nitride phase is distributed very uniformly.

[0079] Example 3

[0080] The difference from Example 1 is that the sintering temperature is 1625 degrees Celsius, the sintering time is 10 seconds, and the weight ratio of the red luminescent nitride phase to the green luminescent oxide phase is 1:5 to 1:15.

[0081] exist Figure 6 The X-ray diffraction patterns show that all these proportions of multiphase fluorescent ceramics can form pure Lu3Al5O3. 12 The phase, and the presence of peaks in the CaAlSiN3 phase can be observed. Figure 7 The emission spectra show that multiphase fluorescent ceramics with a weight ratio of 1:9 to 1:11 can cover a wider spectral band from 480 to 780 nanometers. The color coordinate diagram is shown below. Figure 8 It can be seen that its color coordinates shift from yellow to red as the weight ratio of the red-emitting nitride phase to the green-emitting oxide phase increases.

[0082] Example 4:

[0083] The difference from Example 1 is that the discharge plasma sintering method is used, the sintering temperature is 1625 degrees Celsius, and the sintering holding time is 5 minutes.

[0084] The efficiency of the obtained multiphase fluorescent ceramic is shown in Table 1, with an internal quantum efficiency of 25% and an absorption rate of 0.68.

[0085] Example 5:

[0086] The difference from Example 1 is that the pulse Joule heating sintering method is used, the sintering temperature is 1625 degrees Celsius, and the sintering time is 10 seconds.

[0087] The efficiency of the obtained multiphase fluorescent ceramic is shown in Table 1, with an internal quantum efficiency of 38% and an absorption rate of 0.78.

[0088] Example 6:

[0089] Step 1: Preparation of nitride phase powder

[0090] Using high-purity Ca3N2, AlN, Si3N4, and EuN as raw material powders, according to the general formula Ca 0.992 AlSiN3:0.008Eu was weighed and mixed in a glove box to obtain a raw material mixture powder. The obtained raw material mixture powder was placed in a high-purity boron nitride crucible, and then placed in a pressure furnace. The sintering temperature was 1750 degrees Celsius, the nitrogen pressure was 0.9 MPa, and the holding time was 8 hours. After cooling, Ca was obtained. 0.992 AlSiN3:0.008Eu red phosphor, i.e., nitride phase powder; the prepared nitride phase powder was coated with a 15 nm thick AlN layer using atomic layer deposition equipment to obtain coated nitride phase powder, as shown in the schematic diagram. Figure 2 As shown;

[0091] Step 2: Preparation of Lu2O3 powder

[0092] The preparation of Lu2O3 powder was the same as in Example 1;

[0093] Step 3: Prepare the raw material mixture

[0094] The preparation of the raw material mixture is the same as in Example 1;

[0095] Step 4: Preparation of multiphase fluorescent ceramic bulk green bodies

[0096] The preparation of multiphase fluorescent ceramic bulk green bodies was consistent with that in Example 1;

[0097] Step 5: Sintering

[0098] Multiphase fluorescent ceramic bulk green bodies were sintered in a nitrogen atmosphere using pulsed Joule heating sintering at a temperature of 1625 degrees Celsius for 10 seconds, producing full-spectrum multiphase fluorescent ceramics.

[0099] The efficiency of the obtained multiphase fluorescent ceramic is shown in Table 1. The internal quantum efficiency is 60%, the absorption rate is 0.81, and the color rendering index is 92.

[0100] The full-spectrum multiphase fluorescent ceramics prepared in Examples 4-6 were tested, and the test results are shown in Table 1.

[0101] Table 1:

[0102] Example 4 Example 5 Example 6 Internal quantum efficiency 25％ 38％ 60％ Absorption rate 0.68 0.78 0.81

[0103] In Example 6, compared with Example 5, the prepared multiphase fluorescent ceramic after coating has higher efficiency. The reason is that after coating, the red luminescent nitride phase can be effectively protected during high-temperature sintering, preventing it from reacting, thereby making the sintered multiphase fluorescent ceramic more efficient.

[0104] The preparation method of this invention effectively slows down grain growth during ceramic sintering through short sintering time and rapid heating and cooling rates. Furthermore, during the short sintering process, the nitride powder forms an oxide phase in situ without undergoing significant decomposition or sintering, thus preventing its failure. This promotes dense sintering of both types of ceramics while avoiding the decrease in luminous efficiency caused by oxidation of the nitride phase during prolonged high-temperature processes.

[0105] The full-spectrum multiphase fluorescent ceramic prepared by this invention has promising applications in the field of laser lighting. Through optimized preparation processes and sintering conditions, it exhibits high internal quantum efficiency, and its maximum color rendering index can exceed 90. The integrated full-spectrum multiphase fluorescent ceramic demonstrates significant advantages in heat dissipation and high-power blue laser excitation, making it highly promising for application in the field of full-spectrum laser lighting.

[0106] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A full-spectrum multiphase fluorescent ceramic, characterized in that, Multiphase fluorescent ceramics consist of two phases: a nitride phase and an oxide phase. The chemical composition of the nitride phase is Ca. 1-x-y Sr y AlSiN3: x Eu has the same crystal structure as CaAlSiN3; the chemical composition of the oxide phase is (Lu 1-x-a-b Y a Gd b )3(Al 1-c Ga c )5O 12 : x Ce, whose crystal structure is similar to Lu3Al5O 12 Similarly, in the nitride phase, x=0.008, y=0; in the oxide phase, x=0.01, a=b=c=0. The weight ratio of the nitride phase to the oxide phase in the multiphase fluorescent ceramic is 1:9~1:

11. The full-spectrum multiphase fluorescent ceramic is prepared by the following method: Preparation of nitride phase powder; High-purity Lu2O3 powder, Al2O3 powder, CeO2 powder and nitride phase powder are weighed and mixed according to different weight ratios of nitride phase and oxide phase to obtain a raw material mixture; the raw material mixture is placed in a mortar and a dispersant, flux and alcohol are added to it in sequence, and the mixture is ground to make the raw materials uniformly mixed to obtain a raw material mixture; The raw material mixture is dry-pressed to obtain a multiphase fluorescent ceramic block green body; The obtained multiphase fluorescent ceramic block green body is placed in a muffle furnace for debinding, and then subjected to cold isostatic pressing. It is then subjected to in-situ rapid sintering in a vacuum Joule furnace to obtain full-spectrum multiphase fluorescent ceramic. The in-situ rapid sintering temperature is 1500~1700 degrees Celsius and the sintering time is 8~20 seconds.

2. The full-spectrum multiphase fluorescent ceramic according to claim 1, characterized in that, When excited by a blue light source, multiphase fluorescent ceramics can emit fluorescence with wavelengths covering the range of 480 to 780 nanometers.

3. The full-spectrum multiphase fluorescent ceramic according to claim 1, characterized in that, Preparation of nitride phase powders includes: Using high-purity Ca3N2, Sr3N2, AlN, Si3N4, and EuN as raw material powders, according to the general formula Ca 1-x-y Sr y AlSiN3: x Eu is weighed and mixed in a glove box to obtain a raw material mixture powder. The obtained raw material mixture powder is placed in a high-purity boron nitride crucible, and then placed in a pressure furnace. The sintering temperature is 1600~1800 degrees Celsius, the nitrogen pressure is 0.9 MPa, and the holding time is 4~10 hours. After cooling, Ca is obtained. 1-x-y Sr y AlSiN3: x Eu red phosphor, also known as nitride phase powder.

4. The full-spectrum multiphase fluorescent ceramic according to claim 1, characterized in that, Methods for preparing Lu2O3 powder include: Dissolve 6-10 g of Lu2O3 micron powder in 20 mL of nitric acid and react in a reactor at 80°C for 24 hours. Then add 8-12 mL of supersaturated ammonium bicarbonate solution and react for 4 hours with stirring. After removal, centrifuge with deionized water or ethanol 3-5 times, then dry in an oven at 80°C. After grinding, transfer to a muffle furnace and calcine at 900°C for 2 hours to obtain Lu2O3 powder.

5. The full-spectrum multiphase fluorescent ceramic according to claim 1, characterized in that, The dispersant is ammonium citrate, with an addition dosage of 1~5 wt.%; the flux is tetraethyl orthosilicate, with an addition dosage of 0.1~1 wt.%; and the amount of alcohol added is 5~6 ml. The pressure for dry pressing is 20~60 kN, and the holding time is 2~6 minutes.

6. The full-spectrum multiphase fluorescent ceramic according to claim 1, characterized in that, The debinding conditions in the muffle furnace are 550 degrees Celsius and the debinding time is 12 to 16 hours; the cold isostatic pressing pressure is 250 MPa and the holding time is 180 seconds; in-situ rapid sintering is carried out by fixing the ceramic green body through the sintering medium, under a nitrogen protective atmosphere or a vacuum environment with a vacuum degree not exceeding 0.001 Pa.

7. The application of a full-spectrum multiphase fluorescent ceramic as described in any one of claims 1-6 in the field of laser lighting.

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