Red fluorescent material excited by blue light, LED device and fluorescent ceramic

Abstract

The invention relates to a red fluorescent material excited by blue light, an LED device and fluorescent ceramic. The chemical formula of the red fluorescent material is La (2-x) MgNbO6.5: xEu < 3 + >, wherein x is more than or equal to 0.01 and less than or equal to 0.1. The preparation method comprises the following steps: weighing lanthanum oxide, magnesium oxide, niobium oxide and europium oxide raw materials according to a stoichiometric ratio, grinding and uniformly mixing; sintering the uniformly mixed powder in a muffle furnace at high temperature, and cooling to room temperature to obtain the red fluorescent material. Compared with the prior art, the novel oxide-based red fluorescent powder prepared by the invention can emit positive red light of which the central wavelength is 616nm under the excitation of 465nm blue light, and can be used for white light LED (Light Emitting Diode) luminescent devices and fluorescent ceramics.

Description

Technical Field

[0001] The present invention belongs to the technical field of fluorescent materials, and in particular relates to a red fluorescent material excited by blue light, an LED device and a fluorescent ceramic. Background Art

[0002] White light-emitting diodes (W-LEDs) are widely used in the field of solid-state lighting due to their excellent luminous efficiency, long lifespan, environmental friendliness and stability. Currently, commercial white LEDs mainly rely on the combination of blue LED chips and Y3Al5O 12 :Ce 3+ (YAG:Ce 3+ ) yellow phosphor. However, due to the insufficient red component in this system, its emission spectrum is relatively limited in the red wavelength range, resulting in a relatively high correlated color temperature (CCT) (>4500K) and a low color rendering index (Ra) (<75), making it difficult to meet the requirements of high-quality lighting and full-spectrum applications.

[0003] Red phosphors play a significant role in optimizing the spectrum of white LEDs and improving the color rendering performance. Although traditional red phosphors such as nitride phosphors can improve the color rendering property, their preparation requires harsh conditions, such as high pressure (~9atm) and high temperature (~2000℃), which have high requirements for equipment, complex processes and high costs, limiting their large-scale application.

[0004] The luminescence performance of phosphors is largely affected by the crystal structure of the host material and the chemical environment of the doped ions. Although Mn 4+ -doped fluoride phosphors have certain red light emission ability, their chemical stability is poor, and highly corrosive anhydrous HF needs to be used during the preparation process, presenting safety and environmental protection problems. And Eu 3+ , as an important rare earth luminescent ion, due to the transition characteristics of its 4f electron configuration, can produce strong red light emission in a specific crystal field environment, and its main emission peak is usually in the range of 610 - 620nm, which is suitable for compensating for the red light deficiency in the spectrum of blue light-excited LEDs. Compared with the broadband emission characteristics of Eu 2+ , the emission spectrum of Eu 3+ shows a narrowband feature, the emission peak position is stable, and it is closely related to the crystal structure of the host material. However, commercially common Eu 3+ -doped red phosphors such as CaMoO4:Eu 3+ and Y2O3:Eu 3+ have low luminous intensity, and their luminescence performance still needs to be further improved, thus limiting their application in the preparation of white LED devices. Y2O3:Eu 3+ has a high cost due to its pure rare earth composition. In addition, CN102585831A discloses a Eu 3+Activated fluoromolybdate red phosphor, chemical formula is NaR 4-4x Eu 4x [Mo3O 15 ]F, the activation ion of the red phosphor is europium ion Eu 3+ Its excitation spectrum is in the near-ultraviolet region of 350-400nm and the blue light region around 465nm. However, this red phosphor cannot be adapted to the blue light excitation chip to make LED devices; and the sintering temperature is low. 3+ The maximum preparation temperature of the phosphors does not exceed 1200°C, and they cannot be further made into fluorescent ceramics, which limits the application of the above phosphors in the preparation of fluorescent ceramics.

[0005] Therefore, it is necessary to develop a Eu-doped material with stable physical and chemical properties, low cost and high efficiency of blue light excitation. 3+ Oxide-based red phosphors are of great significance in promoting the development of white light LEDs, solar-like LEDs and fluorescent ceramics. Summary of the Invention

[0006] The purpose of this invention is to overcome the existing Eu-doped 3+ The invention provides a blue light excited red light fluorescent material, LED device and fluorescent ceramic in order to overcome the defects of oxide-based red phosphor in that the luminescence performance needs to be improved and it is difficult to be used in the preparation of white light LED devices and fluorescent ceramics.

[0007] The purpose of the present invention can be achieved by the following technical solutions:

[0008] The present invention first provides a blue light excited red light fluorescent material, characterized in that the chemical formula of the red light fluorescent material is La 2-x MgNbO 6.5 :xEu 3+ , where 0.01≤x≤0.1.

[0009] Furthermore, the excitation spectrum range of the red fluorescent material is 200-550 nm.

[0010] Furthermore, the central excitation wavelength of the red fluorescent material is 465 nm.

[0011] Furthermore, the emission spectrum of the red fluorescent material is in the range of 550-720 nm.

[0012] Furthermore, the central emission wavelength of the red fluorescent material is 616 nm.

[0013] Furthermore, the x is 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09 or 0.1.

[0014] The emission wavelength of the blue-light-excited red fluorescent material of the present invention includes 550 - 720 nm, which can effectively absorb light in the wavelength range of 200 - 550 nm, and can be well matched with the existing blue chips. Under the excitation of 465 nm blue light, it can emit pure red light with a central wavelength of 616 nm. The matrix material of the red fluorescent material is La2MgNbO 6.5 The selection is due to its unique advantages in crystal field regulation and structural stability. By constructing a three-dimensional interpenetrating network of [LaO8] dodecahedra and [NbO6] octahedra (space group Fm-3m), a strong local crystal field is formed, significantly enhancing the f-f transition efficiency of Eu 3+ while suppressing the non-radiative energy loss caused by lattice vibration. The ionic radius matching of La 3+ and Eu 3+ (Δr = 8.1%) follows the Hume-Rothery solid solution rule, realizing equivalent-state substitution (without charge compensation), which not only maintains the lattice symmetry but also improves the doping efficiency. Mg 2+ and Nb 5+ co-occupy the B site to form a stable octahedral coordination, and their synergistic effect optimizes the energy band structure, making the excitation spectrum (465 nm) perfectly match the blue LED chip.

[0015] Furthermore, the red fluorescent material is prepared by the following steps: weighing the raw materials of lanthanum oxide, magnesium oxide, niobium oxide, and europium oxide according to the stoichiometric ratio, grinding and mixing them evenly; subjecting the evenly mixed powder to high-temperature sintering in a muffle furnace, and cooling to room temperature to obtain the red fluorescent material.

[0016] Furthermore, the time for grinding and mixing is 20 - 50 min.

[0017] Furthermore, the high-temperature sintering is carried out in an air atmosphere.

[0018] Furthermore, the temperature of the high-temperature sintering is 1200 - 1600 °C, preferably 1400 - 1500 °C.

[0019] Furthermore, the time for the high-temperature sintering is 6 - 10 h, preferably 8 h.

[0020] Furthermore, the cooling rate is 1 - 5 °C / min, preferably 3 °C / min.

[0021] The present invention also provides an LED device, which includes a blue-light-excited red fluorescent material.

[0022] Furthermore, the LED device is any one of a white light LED device, a solar-like LED device, and a full-spectrum white light LED device.

[0023] Furthermore, the white light LED device is obtained by encapsulating a red fluorescent material and a 465 nm blue LED chip.

[0024] Even further, the color rendering index of the white light LED device is not less than 80. The higher the color rendering index Ra, the stronger the ability of the light source to restore the color of an object. Therefore, the high-Ra white light LED device of the present invention can better restore the true color of an object and is suitable for scenarios requiring high color rendering.

[0025] Even further, the correlated color temperature of the white light LED device is not higher than 4500K, which is suitable for a warm and comfortable lighting environment.

[0026] The present invention also provides a fluorescent ceramic, which contains a red fluorescent material excited by blue light.

[0027] Furthermore, the fluorescent ceramic is prepared from the following raw material components in parts by weight: 90 - 110 parts of red fluorescent material, 2 - 3 parts of monomer, 0.1 - 0.15 parts of crosslinking agent, 1.3 - 3.75 parts of dispersant, 12 - 25 parts of solvent, 0.8 - 2 parts of catalyst, and 0.2 - 1 part of initiator.

[0028] Furthermore, the monomer is N,N-dimethylacrylamide.

[0029] Furthermore, the crosslinking agent is N,N'-methylenebisacrylamide.

[0030] Furthermore, the dispersant is ammonium polyacrylate.

[0031] Furthermore, the catalyst is N,N,N,N,-tetramethylethylenediamine.

[0032] Furthermore, the initiator is ammonium persulfate.

[0033] Furthermore, the fluorescent ceramic is prepared by the following preparation method:

[0034] S1: Add the monomer, dispersant, and crosslinking agent to the solvent for mixing to obtain a premixed solution; then add the red fluorescent material to the premixed solution in batches and perform ball milling to obtain a precursor slurry;

[0035] S2: Add the catalyst to the precursor slurry and perform ball milling to obtain a slurry for injection molding; add the initiator to the slurry for injection molding and then perform injection molding and gelation to obtain a green body;

[0036] S3: Dry the green body, and then sinter it at 1200 - 1700 °C for 12 - 24 h. After sintering, cool it to room temperature to obtain the fluorescent ceramic.

[0037] Further, in step S1, the red fluorescent material is added in three portions, and ball milling is performed for 4 - 12 h after each addition.

[0038] Further, in step S2, the ball milling time is 0.5 - 1.5 h.

[0039] Further, in step S2, an initiator is dropped into the slurry for injection molding, and after rapid stirring for 0.5 - 3 min, immediately use a pre - prepared mold for injection molding, and complete the injection molding operation within 0.5 - 4 min according to the amount of the initiator and the catalyst.

[0040] Further, in step S3, the mold containing the green body is first placed at room temperature to remove part of the water and then solidified and shaped, and then the green body is put into an oven for drying. After 90% of the water is removed, the drying is completed.

[0041] Further, in step S3, the drying temperature is 60 - 90 °C, and the drying time is 24 - 72 h.

[0042] Further, in step S3, the cooling rate is 1 - 5 °C / min.

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

[0044] (1) The novel oxide - based red phosphor La 2-x MgNbO 6.5 :xEu 3+ prepared by the present invention can emit positive red light with a central wavelength located at 616 nm under 465 nm blue - light excitation. Compared with the existing Eu 3+ - doped red phosphor, it has higher fluorescence intensity and stability, and can be well - matched with the existing blue - light chips to package and prepare white LED light - emitting devices.

[0045] (2) The emission wavelength of the blue - light - excited fluorescent material of the present invention includes 550 - 720 nm, which can effectively absorb light in the wavelength range of 200 - 550 nm, and can be well - matched with the existing blue - light chips to meet the commercial market demand, and is suitable for applications in white LEDs, solar - like LEDs, full - spectrum LEDs, etc., providing a new solution for improving the spectral continuity and color rendering performance of LEDs.

[0046] (3) The red fluorescent material excited by blue light prepared in this invention has the advantage of stable physical and chemical properties. It can be prepared by the high-temperature solid-state reaction method, featuring simple preparation process and high purity of the prepared samples. It can be used as a good candidate material for wide applications of white LEDs and has broad application prospects.

[0047] (4) Compared with the similar CaMoO4:Eu 3+ red fluorescent powder, the synthesis temperature of the red fluorescent material of this invention is 1450 °C, which is more suitable for preparing fluorescent ceramics or fluorescent transparent ceramics at high temperature; compared with Y2O3:Eu 3+ with pure rare-earth components, it has more cost advantages. In addition, the red fluorescent material of this invention has higher spectral intensity and a broader spectrum under blue light excitation, higher quantum efficiency, and better luminescence performance, durability and stability than traditional Eu 3+ doped red fluorescent powder.

[0048] (5) The white LED device prepared by encapsulating the red fluorescent powder of this invention with a 465 nm blue light LED chip has a higher color rendering index and a lower correlated color temperature compared with the LED device encapsulated with commercial yellow fluorescent powder (YAG:Ce 3+ ). Its excellent luminescence performance can better restore the true color of objects and is suitable for scenarios requiring high color rendering and warm, comfortable lighting environments.

[0049] (6) Compared with the prior art, for the fluorescent ceramics prepared from the blue light excited red fluorescent material provided by this invention, the traditional resin and silica gel encapsulation materials have low thermal conductivity and are prone to thermal decay of the fluorescent powder due to high temperature under high-energy excitation. However, this invention uses La 2-x MgNbO 6.5 :xEu 3+ as the powder and combines the gel casting molding technology to prepare highly dense fluorescent ceramics, which significantly improves the thermal conductivity and thermal stability. This design effectively enhances the heat dissipation performance, reduces the temperature rise caused by high-energy excitation, slows down the performance decay of the fluorescent powder, and thus significantly extends the service life of the device. This advantage is particularly prominent in high-power lighting and display applications and provides strong support for high-reliability devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 is the photoexcitation-emission spectrum diagram of the red fluorescent materials prepared in Example 1 and Comparative Examples 1 and 2;

[0051] Figure 2 is the XRD diffraction pattern of the red fluorescent material prepared in Example 1;

[0052] Figure 3Photoluminescence excitation-emission spectra of the red fluorescent materials prepared in Example 1, Example 5 and Example 10;

[0053] Figure 4 Electroluminescence spectra of the white light LED devices encapsulated in Example 1 (a) and Comparative Example 3 (b) respectively;

[0054] Figure 5 Photoluminescence excitation-emission spectra of the fluorescent ceramics prepared from the red fluorescent material of Example 9 and the red light fluorescent material of Application Example 2. Detailed implementation manners

[0055] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. These embodiments are implemented on the premise of the technical solutions of the present invention, and detailed implementation manners and specific operation procedures are given. However, the protection scope of the present invention is not limited to the following embodiments.

[0056] Unless otherwise specified, the reagents, methods, instruments and equipment used in the present invention are conventional reagents, methods, instruments and equipment in the art. Unless otherwise specified, the reagents and materials used in the following examples are all commercially available.

[0057] Example 1:

[0058] This example provides a blue light-excited Eu 3+ -doped red fluorescent material, the general formula of which is La 2-x MgNbO 6.5 :xEu 3+ , where x is 0.01. The specific preparation method is as follows:

[0059] (1) Weigh 1 g of raw material powders of La2O3, MgO, Nb2O5, and Eu2O3 according to the stoichiometric ratio (the mass ratio of each raw material is La2O3:MgO:Nb2O5:Eu2O3 = 0.6494:0.0807:0.2662:0.0035).

[0060] (2) Place the obtained raw material mixture in an agate mortar and grind it for 20 - 50 minutes. After the materials are mixed evenly, load the mixture into an alumina crucible, place it in a muffle furnace, and carry out high-temperature calcination at 1200 °C for 6 h in an air atmosphere. Then cool it to room temperature at a rate of 3 °C / min to obtain the blue light-excited red fluorescent material.

[0061] Example 2:

[0062] This example provides a blue light-excited Eu 3+ -doped red fluorescent material, the general formula of which is La 2-x MgNbO 6.5 :xEu 3+, where x is 0.02. The specific preparation method is as follows:

[0063] (1) Weigh 1 g of the raw material powder of La2O3, MgO, Nb2O5, and Eu2O3 according to the stoichiometric ratio (the mass ratio of each raw material is La2O3:MgO:Nb2O5:Eu2O3 = 0.6460:0.0807:0.2661:0.0070).

[0064] (2) Place the obtained raw material mixture in an agate mortar and grind it for 20 - 50 minutes. After the materials are mixed evenly, load the mixture into an alumina crucible, place it in a muffle furnace, and carry out high-temperature calcination at 1250 °C for 6 h in an air atmosphere. Then cool it to room temperature at a rate of 3 °C / min to obtain the red fluorescent material excited by blue light.

[0065] Example 3:

[0066] This example provides a red fluorescent material doped with Eu excited by blue light, and its general formula is La 3+ MgNbO 2-x MgNbO 6.5 :xEu 3+ , where x is 0.03. The specific preparation method is as follows:

[0067] (1) Weigh 1 g of the raw material powder of La2O3, MgO, Nb2O5, and Eu2O3 according to the stoichiometric ratio (the mass ratio of each raw material is La2O3:MgO:Nb2O5:Eu2O3 = 0.6426:0.0807:0.2661:0.0105).

[0068] (2) Place the obtained raw material mixture in an agate mortar and grind it for 20 - 50 minutes. After the materials are mixed evenly, load the mixture into an alumina crucible, place it in a muffle furnace, and carry out high-temperature calcination at 1300 °C for 7 h in an air atmosphere. Then cool it to room temperature at a rate of 3 °C / min to obtain the red fluorescent material excited by blue light.

[0069] Example 4:

[0070] This example provides a red fluorescent material doped with Eu excited by blue light, and its general formula is La 3+ MgNbO 2-x MgNbO 6.5 :xEu 3+ , where x is 0.04. The specific preparation method is as follows:

[0071] (1) Weigh 1 g of the raw material powder of La2O3, MgO, Nb2O5, and Eu2O3 according to the stoichiometric ratio (the mass ratio of each raw material is La2O3:MgO:Nb2O5:Eu2O3 = 0.6391:0.0806:0.2660:0.0140).

[0072] (2) Place the obtained raw material mixture in an agate mortar and grind it for 20 - 50 minutes. After the materials are mixed evenly, load the mixture into an alumina crucible, place it in a muffle furnace, and carry out high-temperature calcination at 1350 °C for 7 h in an air atmosphere. Then cool it to room temperature at a rate of 3 °C / min to obtain a red fluorescent material excited by blue light.

[0073] Example 5:

[0074] This example provides a red fluorescent material doped with Eu excited by blue light, and its general formula is La 3+ MgNbO 2-x MgNbO 6.5 :xEu 3+ , where x is 0.05. The specific preparation method is as follows:

[0075] (1) Weigh 1 g of the raw material powder of La2O3, MgO, Nb2O5, and Eu2O3 according to the stoichiometric ratio (the mass ratio of each raw material is La2O3:MgO:Nb2O5:Eu2O3 = 0.6357:0.0806:0.2659:0.0176).

[0076] (2) Place the obtained raw material mixture in an agate mortar and grind it for 20 - 50 minutes. After the materials are mixed evenly, load the mixture into an alumina crucible, place it in a muffle furnace, and carry out high-temperature calcination at 1400 °C for 8 h in an air atmosphere. Then cool it to room temperature at a rate of 3 °C / min to obtain a red fluorescent material excited by blue light.

[0077] Example 6:

[0078] This example provides a red fluorescent material doped with Eu excited by blue light, and its general formula is La 3+ MgNbO 2-x MgNbO 6.5 :xEu 3+ , where x is 0.06. The specific preparation method is as follows:

[0079] (1) Weigh 1 g of the raw material powder of La2O3, MgO, Nb2O5, and Eu2O3 according to the stoichiometric ratio (the mass ratio of each raw material is La2O3:MgO:Nb2O5:Eu2O3 = 0.6323:0.0806:0.2659:0.0211).

[0080] (2) Place the obtained raw material mixture in an agate mortar and grind it for 20 - 50 minutes. After the materials are evenly mixed, load the mixture into an alumina crucible, place it in a muffle furnace, and perform high-temperature calcination at 1450 °C for 8 h in an air atmosphere. Then cool it to room temperature at a rate of 3 °C / min to obtain a red fluorescent material excited by blue light.

[0081] Example 7:

[0082] This example provides a red fluorescent material doped with Eu 3+ and having a general formula of La 2-x MgNbO 6.5 :xEu 3+ , where x is 0.07. The specific preparation method is as follows:

[0083] (1) Weigh 1 g of raw material powders of La2O3, MgO, Nb2O5, and Eu2O3 according to the stoichiometric ratio (the mass ratio of each raw material is La2O3:MgO:Nb2O5:Eu2O3 = 0.6288:0.0806:0.2658:0.0246).

[0084] (2) Place the obtained raw material mixture in an agate mortar and grind it for 20 - 50 minutes. After the materials are evenly mixed, load the mixture into an alumina crucible, place it in a muffle furnace, and perform high-temperature calcination at 1500 °C for 9 h in an air atmosphere. Then cool it to room temperature at a rate of 3 °C / min to obtain a red fluorescent material excited by blue light.

[0085] Example 8:

[0086] This example provides a red fluorescent material doped with Eu 3+ and having a general formula of La 2-x MgNbO 6.5 :xEu 3+ , where x is 0.08. The specific preparation method is as follows:

[0087] (1) Weigh 1 g of raw material powders of La2O3, MgO, Nb2O5, and Eu2O3 according to the stoichiometric ratio (the mass ratio of each raw material is La2O3:MgO:Nb2O5:Eu2O3 = 0.6254:0.0805:0.2657:0.0281).

[0088] (2) Place the obtained raw material mixture in an agate mortar and grind it for 20 - 50 minutes. After the materials are evenly mixed, load the mixture into an alumina crucible, place it in a muffle furnace, and perform high-temperature calcination at 1550 °C for 9 h in an air atmosphere. Then cool it to room temperature at a rate of 3 °C / min to obtain a red fluorescent material excited by blue light.

[0089] Example 9:

[0090] This example provides a blue-light-excited Eu 3+ -doped red fluorescent material with the general formula La 2-x MgNbO 6.5 :xEu 3+ , where x is 0.09. The specific preparation method is as follows:

[0091] (1) Weigh 1 g of the raw material powder of La2O3, MgO, Nb2O5, and Eu2O3 according to the stoichiometric ratio (the mass ratio of each raw material is La2O3:MgO:Nb2O5:Eu2O3 = 0.6220:0.0805:0.2657:0.0316).

[0092] (2) Place the obtained raw material mixture in an agate mortar and grind it for 20 - 50 minutes. After the materials are mixed evenly, load the mixture into an alumina crucible, place it in a muffle furnace, and carry out high-temperature calcination at 1600 °C for 10 h in an air atmosphere. Then cool it to room temperature at a rate of 3 °C / min to obtain the blue-light-excited red fluorescent material.

[0093] Example 10:

[0094] This example provides a blue-light-excited Eu 3+ -doped red fluorescent material with the general formula La 2-x MgNbO 6.5 :xEu 3+ , where x is 0.1. The specific preparation method is as follows:

[0095] (1) Weigh 1 g of the raw material powder of La2O3, MgO, Nb2O5, and Eu2O3 according to the stoichiometric ratio (the mass ratio of each raw material is La2O3:MgO:Nb2O5:Eu2O3 = 0.6186:0.0805:0.2656:0.0351).

[0096] (2) Place the obtained raw material mixture in an agate mortar and grind it for 20 - 50 minutes. After the materials are mixed evenly, load the mixture into an alumina crucible, place it in a muffle furnace, and carry out high-temperature calcination at 1600 °C for 10 h in an air atmosphere. Then cool it to room temperature at a rate of 3 °C / min to obtain the blue-light-excited red fluorescent material.

[0097] Comparative Example 1:

[0098] This comparative example provides a blue-light-excited Eu 3+ -doped red fluorescent powder with the general formula Y 2-x O3:xEu 3+ , where x is 0.05. The specific preparation method is as follows:

[0099] (1) Use Y2O3 and Eu2O3 as starting materials, with Y2O3:Eu2O3 = 0.9615:0.0384, corresponding to x = 0.05. Weigh the two raw materials separately and control the total mass of the raw material mixture to be 1 g of the mixed raw materials.

[0100] (2) Place the obtained raw material mixture in an agate mortar and grind it for 20 - 50 minutes. After the materials are mixed evenly, load the mixture into an alumina crucible. Then, place the alumina crucible containing the raw materials in the air and calcine it at 1200 °C for 4 h, and then cool it to room temperature to obtain the target product.

[0101] Comparative Example 2:

[0102] This comparative example provides a red phosphor doped with Eu excited by blue light, with the general formula Ca 3+ MoO4:xEu 1-x where x is 0.05. The specific preparation method is as follows: 3+

[0103] (1) Use CaCO3, MoO3, and Eu2O3 as starting materials, with CaCO3:MoO3:Eu2O3 = 0.2854:0.5473:0.1672, corresponding to x = 0.25. Weigh the three raw materials separately and control the total mass of the raw material mixture to be 1 g of the mixed raw materials.

[0104] (2) Place the obtained raw material mixture in an agate mortar and grind it for 20 - 50 minutes. After the materials are mixed evenly, load the mixture into an alumina crucible. Then, place the alumina crucible containing the raw materials in the air and calcine it at 1000 °C for 4 h, and then cool it to room temperature to obtain the target product.

[0105] Comparative Example 3:

[0106] This comparative example provides a yellow phosphor doped with Ce excited by blue light, with the general formula Y 3+ Al5O 3-x :xCe 12 where x is 0.05. The specific preparation method is as follows: 3+

[0107] (1) Use Y2O3, Al2O3, and CeO2 as starting materials, with Y2O3:Al2O3:CeO2 = 0.5681:0.4289:0.0028, corresponding to x = 0.01. Weigh the three raw materials separately and control the total mass of the raw material mixture to be 1 g of the mixed raw materials.

[0108] ​​(2) The obtained raw material mixture was ground in an agate mortar for 20 - 50 minutes. After the materials were evenly mixed, the mixture was loaded into an alumina crucible. Then, the alumina crucible containing the raw materials was calcined in air at 1600 °C for 12 h, and then cooled to room temperature to obtain the target product.

[0109] In this invention, the crystal structure of the fluorescent material prepared in Example 1 was tested using X-ray diffraction (Ultima, IV-185). Cu-Kα was used as the target material for the test, and the scanning angle 2θ ranged from 10 to 80°. The obtained XRD diffraction pattern was as Figure 1 shown. It can be seen from Figure 1 that the fluorescent material is consistent with the standard card, indicating that the doping of Eu 3+ ions did not bring obvious influence to the crystal structure, and the obtained fluorescent material is a pure phase material isomorphic with La2MgNbO 6.5 . The fluorescence emission spectrum data of the fluorescent material show that the emission of the fluorescent material is in the red light region, and it can be used as a very good red light-emitting fluorescent material suitable for white LEDs.

[0110] Furthermore, in this invention, a fluorescence spectrometer (HITACHI, F-7000) was used to test the spectral properties of the above-mentioned phosphor. As shown in the Figure 2 photoexcitation / emission spectrum diagram, the red light phosphor excited by blue light prepared in Example 1 of this invention shows a narrow-band characteristic, the emission peak position is stable, the peak value is located near 616 nm, and the spectral peak value is relatively high, indicating that it can be effectively excited by a blue light chip and matches well with the blue light chip. Under the excitation of a 465 nm blue light source, the phosphor emits bright positive red light, and the emission spectrum peak value is located at 616 nm. In contrast, the spectral intensity of the Y 2-x O3:xEu 3+ phosphor in Comparative Example 1 and the Ca 1-x MoO4:xEu 3+ phosphor in Comparative Example 2 is significantly lower than the spectral intensity of Example 1, indicating that the red phosphor of this invention has better luminescence effect, and its durability and stability are also significantly higher than those of the existing Eu 3+ doped red phosphors.

[0111] In addition, as shown in the Figure 3 photoexcitation / emission spectrum diagram, the red phosphors in Examples 2 - 10 all have similar photoluminescence properties to those in Example 1, and can all emit bright positive red light under the excitation of a 465 nm blue light source.

[0112] Application Example 1:

[0113] This application example provides an application of a blue light-excited red phosphor in the preparation of LED devices.

[0114] Specifically, in this application example, the red phosphor prepared in Example 1 and the yellow phosphor in Comparative Example 3 were respectively encapsulated with a 465 nm blue LED chip to prepare white LED devices, and an automatic temperature-controlled LED photoelectric analyzer (HAAS-2000) was used to test the luminous performance of the above-mentioned encapsulated white LED devices, obtaining the electroluminescence spectrograms shown in Figure 4 Figures 4a and 4b.

[0115] As can be seen from Figure 4 Figure 4a, the color rendering index Ra of the high-performance white LED encapsulated with the red phosphor prepared by the present invention is as high as 88.3, and the correlated color temperature CCT is as low as 4462K, indicating that the white LED of the present invention can better restore the true color of objects, is suitable for scenarios requiring high color rendering, and is suitable for warm and comfortable lighting environments. While the color rendering index of the white LED encapsulated with the yellow phosphor is only 68.3, and the correlated color temperature is as high as 4940K.

[0116] From the above results, it can be seen that the Eu 3+ doped La2MgNbO 6.5 red phosphor prepared by the present invention has excellent application potential in white LED devices based on blue LED chips, can meet the commercial market demand, and is further adaptable to applications such as white LED, solar-like LED, and full-spectrum LED.

[0117] Application Example 2:

[0118] This application example provides a red fluorescent ceramic prepared from the red fluorescent material of Example 9, and its specific preparation method is as follows:

[0119] (1) Pulp ball milling:

[0120] Take 2.5 g of monomer (N,N-dimethylacrylamide), 0.13 g of cross-linking agent (N,N'-methylenebisacrylamide), and 3.25 g of dispersant (ammonium polyacrylate, 40 wt%) and add them to 15 g of deionized water, stir evenly to obtain a premixed solution. Add 60 g of red fluorescent ceramic precursor powder (i.e., La 1.91 MgNbO 6.5 :0.09Eu 3+ ) to the premix and stir to obtain a slurry. Add the slurry and grinding balls to a ball mill tank (the mass ratio of grinding balls to slurry is 1:1) for the first ball milling, and the ball milling time is 6 h; then add 20 g of red fluorescent ceramic precursor powder (La 1.91 MgNbO 6.5 :0.09Eu 3+ ) for the second ball milling, and the ball milling time is 6 h; then add 20 g of red fluorescent ceramic precursor powder (La 1.91 MgNbO6.5 : 0.09Eu 3+ ) and perform the third ball milling for 6 h to obtain the slurry for injection molding.

[0121] (2) Gelcasting:

[0122] Add 1.5 g of catalyst (N,N,N,N,-tetramethylethylenediamine, 5 wt%) to the slurry for injection molding and perform the fourth ball milling for 0.5 h. Then add 0.5 g of initiator (ammonium persulfate, 1.5 wt%), stir rapidly for 0.5 min, and immediately use the pre-prepared mold for injection molding to obtain a green body.

[0123] (3) Drying and dehydration:

[0124] After the green body is cured and shaped, place it in an oven at 80 °C and dry for 48 h. After 90% of the water is removed, the drying is completed.

[0125] (4) Sintering treatment:

[0126] Transfer the dried blank to a muffle furnace and sinter at 1600 °C for 24 h. After sintering, cool it to room temperature at a rate of 5 °C / min to obtain the red fluorescent ceramic.

[0127] The fluorescent ceramic prepared from the blue-light-excited red fluorescent material prepared by the present invention has a Figure 5 photoluminescence excitation-emission spectrum diagram as follows. Under the excitation of a blue-light source at 465 nm, the fluorescent ceramic emits bright pure red light, the peak of the emission spectrum is located at 616 nm, and the luminous intensity is 1.575 times that before sintering, and the luminous intensity is further improved. And compared with traditional fluorescence conversion materials, it has better thermal conductivity, reduces the temperature rise caused by high-energy excitation, slows down the performance decay of the phosphor, and thus significantly extends the service life of the device, and has the application potential as a fluorescence conversion material under the condition of a high-power density excitation source.

[0128] The above description of the embodiments is for the convenience of those of ordinary skill in the art to understand and use the invention. Those skilled in the art can obviously make various modifications to these embodiments easily and apply the general principles described herein to other embodiments without creative labor. Therefore, the present invention is not limited to the above embodiments, and the improvements and modifications made by those skilled in the art without departing from the scope of the present invention according to the disclosure of the present invention should be within the protection scope of the present invention.

Claims

1. A blue light-excited red fluorescent material, characterized in that, The chemical formula of the red fluorescent material is La 2- x MgNbO 6.5 :xEu 3+ , where 0.01 ≤ x ≤ 0.1; The excitation spectrum range of the red fluorescent material is 200 - 550 nm; The emission spectrum range of the red fluorescent material is 550 - 720 nm.

2. The red fluorescent material excited by blue light according to claim 1, characterized in that, The x is 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09 or 0.

1.

3. The red fluorescent material excited by blue light according to claim 1, characterized in that, The central excitation wavelength of the red fluorescent material is 465 nm; The central emission wavelength of the red fluorescent material is 616 nm.

4. A red fluorescent material excited by blue light according to claim 1, characterized in that, The red fluorescent material is prepared by the following steps: Weigh the raw materials of lanthanum oxide, magnesium oxide, niobium oxide and europium oxide according to the stoichiometric ratio, grind and mix them evenly; sinter the evenly mixed powder at high temperature in a muffle furnace, and the red fluorescent material can be obtained after cooling to room temperature.

5. The red fluorescent material excited by blue light according to claim 4, characterized in that, The high-temperature sintering is carried out in an air atmosphere, the temperature of the high-temperature sintering is 1200 - 1600 °C, and the time of the high-temperature sintering is 6 - 10 h; The cooling rate is 1 - 5 °C / min.

6. An LED device, characterized in that, Comprising the red fluorescent material excited by blue light according to any one of claims 1 - 5; the LED device is any one of a white LED device, a solar-like LED device, and a full-spectrum white LED device.

7. An LED device according to claim 6, characterized in that, The white LED device is prepared by encapsulating a red fluorescent material and a 465 nm blue LED chip; The color rendering index of the white LED device is not less than 80; The correlated color temperature of the white LED device is not higher than 4500 K.

8. A fluorescent ceramic, characterized in that, Comprising the red fluorescent material excited by blue light according to any one of claims 1 - 5; The fluorescent ceramic is prepared from the following raw material components in parts by weight: 90 - 110 parts of red fluorescent material, 2 - 3 parts of monomer, 0.1 - 0.15 parts of cross-linking agent, 1.3 - 3.75 parts of dispersant, 12 - 25 parts of solvent, 0.8 - 2 parts of catalyst, and 0.2 - 1 part of initiator.

9. A fluorescent ceramic according to claim 8, wherein, The monomer is N,N-dimethylacrylamide, the cross-linking agent is N,N'-methylenebisacrylamide, the dispersant is ammonium polyacrylate, the catalyst is N,N,N,N-tetramethylethylenediamine, and the initiator is ammonium persulfate.

10. A fluorescent ceramic according to claim 8, wherein, The fluorescent ceramic is prepared by the following preparation method: S1: Add the monomer, dispersant and cross-linking agent into the solvent for mixing to obtain a premixed solution; then add the red fluorescent material to the premixed solution in batches and carry out ball milling to obtain a precursor slurry; S2: Add the catalyst to the precursor slurry and carry out ball milling to obtain a slurry for injection molding; add the initiator to the slurry for injection molding and then carry out injection molding and gelation to obtain a green body; S3: Dry the green body, and then sinter it at 1200 - 1700 °C for 12 - 24 h, and cool it to room temperature after sintering to obtain the fluorescent ceramic.

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