High-thermal-stability dark red light fluorescent material, preparation method and LED light source

Abstract

The invention relates to a high-thermal-stability dark red light fluorescent material, a preparation method and an LED light source. The fluorescent material is a La2O3-MgO-A2O5-Sm2O3 system, wherein A is selected from one or a combination of more of Nb, Ta or Sb; in the La2O3-MgO-A2O5-Sm2O3 system, the molar ratio of La to Mg to A to Sm is (1.9 to 1.99) to 1 to 1 to (0.01 to 0.1). The preparation method comprises the following steps: weighing a La source compound, a Mg source compound, an A source compound and a samarium source compound in proportion, grinding and mixing the raw materials, and performing primary sintering to obtain a precursor; grinding and mixing the precursor for the second time, and sintering for the second time to obtain the dark red light fluorescent material. Compared with the prior art, the dark red light fluorescent material can effectively absorb purple light with the wavelength of 400-410 nm, emits intense red light with the central wavelength of 650 nm, and can be well matched with a purple light chip to package and prepare an LED light-emitting device.

Description

Technical Field

[0001] The present invention belongs to the technical field of fluorescent materials, and particularly relates to a deep red fluorescent material with high thermal stability, a preparation method thereof, and an LED light source. Background Art

[0002] With the development of the LED industry, people's demand for white light has shifted to full-spectrum healthy white light similar to sunlight. However, in the current mainstream white light solution combining blue chips and multicolor phosphors, the obtained white light lacks violet components, cannot well simulate sunlight, and the chips will emit excessive blue light, which is harmful to humans. Compared with the above solution, the white light solution combining violet (400 - 420 nm) InGaN chips and multicolor phosphors is more likely to generate full-spectrum white light similar to the solar spectrum, while avoiding blue light hazards and can provide a healthier WLED. Therefore, multicolor phosphors excited by violet LED chips have gradually become a research hotspot.

[0003] Compared with phosphors excited by blue light, phosphors excited by violet light are relatively scarce, and there are few reports on long-wavelength emission (orange-red, red) phosphors that can be excited by violet light, most of which are nitrides or fluorides. As is well known, nitride phosphors are usually prepared under harsh conditions such as high temperature and high pressure, with high costs; while fluoride phosphors have unstable chemical properties and generally poor thermal stability. Therefore, there is still an urgent need for oxide-based violet-excited long-wavelength emission phosphors with high thermal stability.

[0004] In addition, the thermal quenching (TQ) characteristic is a common characteristic of phosphors, and this negative characteristic can directly affect the quality of the light source (because a large amount of heat is generated when the chip is working, about 150 °C). Therefore, researchers have been committed to developing phosphors with better thermal stability to reduce the negative impact of the thermal effect on the continuous lighting of LEDs. CN116751590A discloses a fluorescent material capable of stably and efficiently emitting far red light, by doping Bi 3+ and rare earth ions in a scandate matrix and substituting Sc 3 + with Mn 4+ , solving the problems of low luminous efficiency and poor thermal stability of existing Mn 4+ -doped red fluorescent phosphors, and realizing efficient emission of far red light under near-ultraviolet light. However, this far red fluorescent material still cannot be adapted to violet LED chips and is not suitable for preparing violet-excited white LED devices.

[0005] Therefore, there is still a need to develop a new type of oxide-based deep red fluorescent phosphor with strong absorption in the violet region and high thermal stability to meet the market demand for violet-excited white LED light source devices. Summary of the Invention

[0006] The object of the present invention is to provide a deep red light fluorescent material with high thermal stability, a preparation method and an LED light source, so as to develop a new oxide-based deep red phosphor with strong absorption in the ultraviolet region and high thermal stability, so as to meet the market demand of white LED light source devices excited by ultraviolet light.

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

[0008] The present invention provides a deep red light fluorescent material with high thermal stability, and the fluorescent material is a La2O3-MgO-A2O5-Sm2O3 system, where A is selected from Nb, Ta or Sb;

[0009] In the La2O3-MgO-A2O5-Sm2O3 system, the molar ratio of La:Mg:A:Sm is (1.9-1.99):1:1:(0.01-0.1).

[0010] Further, in the La2O3-MgO-A2O5-Sm2O3 system, the molar ratio of La:Mg:A:Sm is (1.9-1.99):1:1:(0.01-0.1). When Sm is not doped, this system will not emit light; when the doping of Sm is excessive, concentration quenching will occur and the luminescence intensity will instead decrease.

[0011] Further, in the La2O3-MgO-A2O5-Sm2O3 system, the molar ratio of La:Mg:A:Sm is 1.99:1:1:0.01 or 1.98:1:1:0.02 or 1.97:1:1:0.03.

[0012] Further, in the La2O3-MgO-A2O5-Sm2O3 system, the components are calculated by mass percentage of oxides as follows: 52.62% ≤ La2O3 ≤ 64.95%, 6.85% ≤ MgO ≤ 8.07%, 26.57% ≤ A2O5 ≤ 37.63%, 0.30% ≤ Sm2O3 ≤ 3.49%.

[0013] Further, the excitation spectrum range of the fluorescent material is 365-385 nm, 400-410 nm and 475-500 nm.

[0014] Furthermore, the best excitation spectrum range of the fluorescent material is 400-410 nm, preferably 405-410 nm, and the best excitation is at 407 nm, which can be adapted to commercially available 410 nm ultraviolet excitation chips.

[0015] Further, the emission center wavelength of the fluorescent material is 650 nm, accompanied by multi-peak narrow band emissions at 550-625 nm and 675-750 nm.

[0016] Furthermore, the color coordinates of the fluorescent material are (0.627, 0.369).

[0017] The phosphor of the present invention is an Sm 3+ -doped oxide-based red light-emitting fluorescent material. In the La2O3-MgO-A2O5-Sm2O3 system of the present invention, the oxide matrix composed of La2O3, MgO and A2O5 has the advantages of good stability and easy preparation. Sm 3+ Ion doping can obtain luminescence properties with the best excitation value in the ultraviolet region.

[0018] The present invention also provides a preparation method of the deep red light fluorescent material with high thermal stability, which specifically includes the following steps:

[0019] S1: Weigh the La source compound, Mg source compound, A source compound and samarium source compound according to the proportion, and grind and mix the raw materials to obtain a mixture;

[0020] S2: Sinter the mixture obtained in S1 for the first time to obtain a precursor;

[0021] S3: After secondary grinding and mixing of the precursor obtained in S2, perform secondary sintering to obtain the deep red light fluorescent material.

[0022] Furthermore, in step S1, the La source compound, Mg source compound, A source compound and samarium source compound are each independently selected from one or more of the corresponding metal element's simple substance, oxide, chloride, sulfide, carbonate, sulfate, phosphate, nitrate.

[0023] Furthermore, in step S1, the grinding time is 5 - 120 min, preferably 20 - 50 min.

[0024] Furthermore, in step S2, the first sintering is carried out in an air atmosphere.

[0025] Furthermore, in step S2, the temperature of the first sintering is 200 - 800 °C, preferably 300 - 650 °C.

[0026] Furthermore, in step S2, the time of the first sintering is 5 - 24 h, preferably 5 - 12 h.

[0027] Furthermore, in step S3, the secondary grinding time is 5 - 120 min, preferably 20 - 50 min.

[0028] Furthermore, in step S3, the secondary sintering is carried out in an inert atmosphere.

[0029] Furthermore, the inert atmosphere is selected from one or more of nitrogen, helium, and argon.

[0030] Further, in step S3, the temperature of the secondary sintering is 1000 - 1700 °C, preferably 1200 - 1550 °C.

[0031] Further, in step S3, the time of the secondary sintering is 1 - 24 h, preferably 4 - 18 h.

[0032] Further, the system pressure during the primary sintering and the secondary sintering is maintained at 1 standard atmosphere.

[0033] The present invention also provides an application of a deep red light fluorescent material with high thermal stability in the preparation of an LED light source.

[0034] Further, the LED light source includes a near - ultraviolet light - excited white LED light source, a near - ultraviolet light - excited solar - like LED light source, a near - ultraviolet light - excited full - spectrum LED light source, or a near - ultraviolet light - excited high - quality white LED light source.

[0035] The present invention also provides one of the LED light sources, which is prepared by encapsulating a deep red light fluorescent material, a blue phosphor, a green phosphor, and a near - ultraviolet chip.

[0036] Further, the color rendering index of the LED light source is not less than 90, having a relatively high color rendering index.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] (1) The deep red light fluorescent material of the present invention can be excited by near - ultraviolet light, violet light, and blue light, can effectively absorb violet light with a wavelength of 400 - 410 nm, and emit strong red light with a central wavelength located at 650 nm. It has good luminescence performance and thermal stability, and can be well - matched with a near - ultraviolet chip for encapsulating and preparing an LED light - emitting device.

[0039] (2) The optimal excitation wavelength of the deep red light phosphor of the present invention is located in the violet light region, which can be well - matched with the existing near - ultraviolet chips. It has excellent luminescence performance, meets the requirements of the commercial market, and has great development potential in the field of healthy lighting such as near - ultraviolet light - excited white LEDs, near - ultraviolet light - excited solar - like LEDs, and near - ultraviolet light - excited full - spectrum LEDs.

[0040] (3) The deep red light phosphor of the present invention is a Sm 3+ doped oxide - based red - light - emitting fluorescent material, which has the advantage of stable physical and chemical properties; at the same time, the phosphor of the present invention can be prepared by a solid - phase reaction method, and has the characteristics of simple preparation process, low cost, and being conducive to industrial production.

[0041] (4) The deep red phosphor of the present invention has excellent thermal quenching resistance and can still maintain more than 90% of the luminescence intensity at 150 °C, which can ensure that it still has excellent luminescence performance when the LED chip is working, so as to reduce the negative impact of the thermal effect on the continuous illumination of the LED.

[0042] (5) The deep red phosphor of the present invention can be encapsulated with commercial blue phosphors and green phosphors to prepare LED devices, and shows a higher color rendering index and a lower color temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is the photoluminescence excitation-emission spectrum diagram of the deep red fluorescent materials in Examples 1-3 of the present invention.

[0044] Figure 2 It is the XRD spectrum diagram of the deep red fluorescent materials in Examples 1-3 of the present invention.

[0045] Figure 3 It is the test result of the thermal stability of the deep red fluorescent material in Example 1 of the present invention.

[0046] Figure 4 It is the electroluminescence spectrum diagram of the LED device prepared by encapsulating the red phosphor in Example 1 with commercial blue and green phosphors. DETAILED DESCRIPTION OF THE INVENTION

[0047] The present invention will be described in detail below with reference to the drawings and specific embodiments. This embodiment is implemented on the premise of the technical solution of the present invention, and the detailed implementation manners and specific operation processes are given, but the protection scope of the present invention is not limited to the following embodiments.

[0048] Unless otherwise specified, the equipment used in the following embodiments represents conventional equipment in the art; unless otherwise specified, the reagents used represent commercially available products or are prepared by conventional methods in the art. Those not described in detail in the following embodiments can be achieved by conventional experimental means in the art.

[0049] Example 1:

[0050] This example provides a deep red fluorescent material with ultraviolet excitation and high thermal stability, which is applied to the preparation of LED light sources. The specific steps are as follows:

[0051] (1) Lanthanum oxide (La2O3), magnesium oxide (MgO), niobium pentoxide (Nb2O5), and samarium oxide (Sm2O3) were selected as starting materials, with La:Mg:Nb:Sm = 1.99:1:1:0.01 (molar ratio). The four raw material powders were weighed respectively according to the stoichiometric ratio, and the total mass of the raw material powders was controlled to be 10 g. Each raw material powder was placed in an agate mortar and ground thoroughly for 20 min to be mixed evenly, obtaining a mixture.

[0052] (2) The mixture was placed in an alumina crucible, and the alumina crucible containing the mixture was placed in a muffle furnace. It was calcined at 300 °C for 5 h in an air atmosphere, with the pressure maintained at 1 atm, and then cooled naturally to room temperature to obtain a precursor.

[0053] (3) The precursor was placed in an agate mortar again and ground thoroughly for 20 min to be mixed evenly. The precursor was placed in an alumina crucible, and the alumina crucible containing the precursor was placed in a vacuum tube furnace. After evacuation, it was sintered at 1200 °C for 4 h in an inert atmosphere of nitrogen, with the pressure maintained at 1 atm, and then cooled naturally to room temperature to obtain a powdery deep red light fluorescent material with high thermal stability excited by violet light.

[0054] Example 2:

[0055] This example provides a deep red light fluorescent material with violet light excitation and high thermal stability, and its preparation method is basically the same as that of Example 1. The differences are that in step S1, La:Mg:Nb:Sm = 1.98:1:1:0.02 (molar ratio), in step S2, it was calcined at 350 °C for 6 h in an air atmosphere, and in step S3, it was sintered at 1250 °C for 6 h in an inert atmosphere of nitrogen (N2). The specific steps are as follows:

[0056] (1) Lanthanum oxide, magnesium oxide, niobium pentoxide, and samarium oxide were selected as starting materials, with La:Mg:Nb:Sm = 1.98:1:1:0.02 (molar ratio). The four raw material powders were weighed respectively according to the stoichiometric ratio, and the total mass of the raw material powders was controlled to be 10 g. Each raw material powder was placed in an agate mortar and ground thoroughly for 20 min to be mixed evenly, obtaining a mixture.

[0057] (2) The mixture was placed in an alumina crucible, and the alumina crucible containing the mixture was placed in a muffle furnace. It was calcined at 350 °C for 6 h in an air atmosphere and then cooled naturally to room temperature to obtain a precursor.

[0058] (3) Place the precursor in an agate mortar again and grind it thoroughly for 20 min to mix evenly. Place the precursor in an alumina crucible, and then place the alumina crucible containing the precursor in a vacuum tube furnace. Evacuate the air, maintain it in an inert atmosphere of nitrogen, sinter at 1250 °C for 6 h, keep the pressure at 1 atm, and cool it naturally to room temperature to obtain a powdery deep red light fluorescent material with high thermal stability excited by violet light.

[0059] Example 3:

[0060] This example provides a deep red light fluorescent material with high thermal stability excited by violet light, and its preparation method is basically the same as that of Example 1. The differences are as follows: in step S1, La:Mg:Nb:Sm = 1.97:1:1:0.03 (molar ratio); in step S2, calcine at 400 °C in an air atmosphere for 7 h; in step S3, sinter at 1300 °C in an inert atmosphere of nitrogen (N2) for 8 h. The specific steps are as follows:

[0061] (1) Select lanthanum oxide, magnesium oxide, niobium pentoxide, and samarium oxide as starting materials, with La:Mg:Nb:Sm = 1.97:1:1:0.03 (molar ratio). Weigh the four raw material powders according to the stoichiometric ratio respectively, control the total mass of the raw material powders to be 10 g, place the raw material powders in an agate mortar and grind them thoroughly for 20 min to mix evenly to obtain a mixture.

[0062] (2) Place the mixture in an alumina crucible, and then place the alumina crucible containing the mixture in a muffle furnace. Calcine at 400 °C in an air atmosphere for 7 h and cool it naturally to room temperature to obtain a precursor.

[0063] (3) Place the precursor in an agate mortar again and grind it thoroughly for 20 min to mix evenly. Place the precursor in an alumina crucible, and then place the alumina crucible containing the precursor in a vacuum tube furnace. Evacuate the air, maintain it in an inert atmosphere of nitrogen, sinter at 1300 °C for 8 h, keep the pressure at 1 atm, and cool it naturally to room temperature to obtain a powdery deep red light fluorescent material with high thermal stability excited by violet light.

[0064] Example 4:

[0065] This example provides a deep red light fluorescent material with high thermal stability excited by violet light, and its preparation method is basically the same as that of Example 1. The differences are as follows: in step S1, La:Mg:Ta:Sm = 1.99:1:1:0.01 (molar ratio); in step S2, calcine at 450 °C in an air atmosphere for 8 h; in step S3, sinter at 1350 °C in an inert atmosphere of helium (He) for 10 h. The specific steps are as follows:

[0066] (1) Select lanthanum oxide, magnesium oxide, tantalum pentoxide, and samarium oxide as starting materials, with La:Mg:Ta:Sm = 1.99:1:1:0.01 (molar ratio). Weigh the four raw material powders according to the stoichiometric ratio respectively, control the total mass of the raw material powders to be 10 g, place each raw material powder in an agate mortar and grind thoroughly for 20 min to mix evenly, obtaining a mixture.

[0067] (2) Place the mixture in an alumina crucible, and place the alumina crucible containing the mixture in a muffle furnace. Calcinate it at 450 °C for 8 h in an air atmosphere, and then cool it naturally to room temperature to obtain a precursor.

[0068] (3) Place the precursor in an agate mortar again and grind thoroughly for 20 min to mix evenly. Place the precursor in an alumina crucible, and place the alumina crucible containing the precursor in a vacuum tube furnace. Evacuate the air, sinter it at 1350 °C for 10 h in an inert atmosphere of nitrogen, keep the pressure at 1 atm, and then cool it naturally to room temperature to obtain a powdery deep red light fluorescent material with high thermal stability excited by ultraviolet light.

[0069] Example 5:

[0070] This example provides a deep red light fluorescent material with high thermal stability excited by ultraviolet light, and its preparation method is basically the same as that of Example 1. The differences are as follows: in step S1, La:Mg:Ta:Sm = 1.98:1:1:0.02 (molar ratio); in step S2, calcinate it at 500 °C for 9 h in an air atmosphere; in step S3, sinter it at 1350 °C for 10 h in an inert atmosphere of helium (He). The specific steps are as follows:

[0071] (1) Select lanthanum oxide, magnesium oxide, tantalum pentoxide, and samarium oxide as starting materials, with La:Mg:Ta:Sm = 1.98:1:1:0.02 (molar ratio). Weigh the four raw material powders according to the stoichiometric ratio respectively, control the total mass of the raw material powders to be 10 g, place each raw material powder in an agate mortar and grind thoroughly for 20 min to mix evenly, obtaining a mixture.

[0072] (2) Place the mixture in an alumina crucible, and place the alumina crucible containing the mixture in a muffle furnace. Calcinate it at 500 °C for 9 h in an air atmosphere, and then cool it naturally to room temperature to obtain a precursor.

[0073] (3) Place the precursor in an agate mortar again and grind thoroughly for 20 min to mix evenly. Place the precursor in an alumina crucible, and place the alumina crucible containing the precursor in a vacuum tube furnace. Evacuate the air, sinter it at 1400 °C for 1 * 2 h in an inert atmosphere of nitrogen, keep the pressure at 1 atm, and then cool it naturally to room temperature to obtain a powdery deep red light fluorescent material with high thermal stability excited by ultraviolet light

[0074] Example 6:

[0075] This example provides a deep red light fluorescent material excited by ultraviolet light and having high thermal stability. Its preparation method is basically the same as that of Example 1. The differences are that in step S1, La:Mg:Ta:Sm = 1.97:1:1:0.03 (molar ratio), in step S2, it is calcined at 550 °C for 10 h in an air atmosphere, and in step S3, it is sintered at 1400 °C for 12 h in an inert atmosphere of helium (He). The specific steps are as follows:

[0076] (1) Select lanthanum oxide, magnesium oxide, tantalum pentoxide, and samarium oxide as starting materials, with La:Mg:Ta:Sm = 1.97:1:1:0.03 (molar ratio). Weigh the four raw material powders according to the stoichiometric ratio respectively, control the total mass of the raw material powders to be 10 g, place each raw material powder in an agate mortar and grind it thoroughly for 20 min to mix evenly, obtaining a mixture.

[0077] (2) Place the mixture in an alumina crucible, place the alumina crucible containing the mixture in a muffle furnace, calcine it at 550 °C for 10 h in an air atmosphere, and cool it naturally to room temperature to obtain a precursor.

[0078] (3) Place the precursor in an agate mortar again and grind it thoroughly for 20 min to mix evenly. Place the precursor in an alumina crucible, place the alumina crucible containing the precursor in a vacuum tube furnace, evacuate it, sinter it at 1450 °C for 14 h in an inert atmosphere of nitrogen, keep the pressure at 1 atm, and cool it naturally to room temperature to obtain a powdery deep red light fluorescent material excited by ultraviolet light and having high thermal stability.

[0079] Example 7:

[0080] This example provides a deep red light fluorescent material excited by ultraviolet light and having high thermal stability. Its preparation method is basically the same as that of Example 1. The differences are that in step S1, La:Mg:Sb:Sm = 1.99:1:1:0.01 (molar ratio), in step S2, it is calcined at 600 °C for 11 h in an air atmosphere, and in step S3, it is sintered at 1500 °C for 16 h in an inert atmosphere of helium (He). The specific steps are as follows:

[0081] (1) Select lanthanum oxide, magnesium oxide, antimony pentoxide, and samarium oxide as starting materials, with La:Mg:Sb:Sm = 1.99:1:1:0.01 (molar ratio). Weigh the four raw material powders according to the stoichiometric ratio respectively, control the total mass of the raw material powders to be 10 g, place each raw material powder in an agate mortar and grind it thoroughly for 20 min to mix evenly, obtaining a mixture.

[0082] (2) Place the mixture in an alumina crucible, and place the alumina crucible containing the mixture in a muffle furnace. Calcinate at 600 °C for 11 h in an air atmosphere, and naturally cool to room temperature to obtain a precursor.

[0083] (3) Place the precursor in an agate mortar and grind it thoroughly for 20 min to mix evenly. Place the precursor in an alumina crucible, and place the alumina crucible containing the precursor in a vacuum tube furnace. Evacuate the air, and sinter at 1500 °C for 16 h in an inert atmosphere of nitrogen. Keep the pressure at 1 atm, and naturally cool to room temperature to obtain a powdery deep red light-emitting phosphor with high thermal stability excited by violet light.

[0084] Example 8:

[0085] This example provides a deep red light-emitting phosphor with high thermal stability excited by violet light, and its preparation method is basically the same as that of Example 1. The differences are as follows: in step S1, La:Mg:Sb:Sm = 1.98:1:1:0.02 (molar ratio); in step S2, calcinate at 650 °C for 12 h in an air atmosphere; in step S3, sinter at 1550 °C for 18 h in an inert atmosphere of helium (He). The specific steps are as follows:

[0086] (1) Select lanthanum oxide, magnesium oxide, antimony pentoxide, and samarium oxide as starting materials, with La:Mg:Sb:Sm = 1.98:1:1:0.02 (molar ratio). Weigh the four raw material powders according to the stoichiometric ratio respectively, control the total mass of the raw material powders to be 10 g, and place each raw material powder in an agate mortar and grind it thoroughly for 20 min to mix evenly to obtain a mixture.

[0087] (2) Place the mixture in an alumina crucible, and place the alumina crucible containing the mixture in a muffle furnace. Calcinate at 650 °C for 12 h in an air atmosphere, and naturally cool to room temperature to obtain a precursor.

[0088] (3) Place the precursor in an agate mortar and grind it thoroughly for 20 min to mix evenly. Place the precursor in an alumina crucible, and place the alumina crucible containing the precursor in a vacuum tube furnace. Evacuate the air, and sinter at 1550 °C for 18 h in an inert atmosphere of nitrogen. Keep the pressure at 1 atm, and naturally cool to room temperature to obtain a powdery deep red light-emitting phosphor with high thermal stability excited by violet light.

[0089] First, the present invention uses a fluorescence spectrometer (HITACHI F-7500) to test the spectral properties of the phosphors in the above examples and comparative examples. As Figure 1As shown, the results indicate that the deep red phosphor in Example 1 can be excited by near-ultraviolet, violet or blue light. The peak of the excitation spectrum is located in the violet region, and the central wavelength of the emission spectrum is 650 nm. Under the excitation of a 410 nm violet light source, the phosphor in Example 1 emits bright red light, and the emission spectrum consists of multiple narrow emission peaks with a peak at 650 nm. This shows that the phosphor in Example 1 can be effectively excited by a violet chip and can be well matched with a commercial violet chip. The deep red phosphors in Example 2 and Example 3 can also emit bright red light under the excitation of a 410 nm violet light source, with a peak at 650 nm. In addition, the La2O3-MgO-TA2O5-Sm2O3 fluorescent materials prepared in Examples 4-6 and the La2O3-MgO-Sb2O5-Sm2O3 fluorescent materials prepared in Examples 7-8 can all emit bright red light under the excitation of a 410 nm violet light source, indicating that the Sm 3+ -doped La2O3-MgO-A2O5-Sm2O3 system deep red fluorescent materials all have good luminescence properties.

[0090] Secondly, the present invention uses X-ray diffraction to test the crystal structure of the fluorescent materials prepared in Examples 1-3. Cu-Kα is used as the target material for the test, and the scanning angle 2θ ranges from 10° to 80°. The obtained XRD diffraction pattern is as Figure 2 shown. It can be seen from Figure 2 that the fluorescent material is consistent with the standard card, indicating that the present invention has prepared a pure-phase phosphor, and the doping of Sm 3+ ions has no obvious effect on the crystal structure.

[0091] Furthermore, the thermal quenching characteristics of the phosphor will directly affect the quality of the light source. Therefore, a phosphor with high thermal stability can effectively reduce the negative impact of the thermal effect on the continuous lighting of the LED. The present invention conducts a thermal stability test on the prepared fluorescent materials (Hitachi F7000). The Figure 3 results show that, taking the deep red fluorescent material in Example 1 as an example, at 120 °C, the luminous intensity is 95.1% of that at room temperature; at 150 °C, the luminous intensity is 92.3% of that at room temperature. Therefore, in the high-temperature environment generated by the operation of the LED chip, the deep red fluorescent material of the present invention can still maintain a high luminous intensity and has excellent anti-thermal quenching performance.

[0092] To verify that the deep red fluorescent material of the present invention can be used to prepare pc-LED devices, the following electroluminescence test is carried out: The deep red phosphor in Example 1 is mixed with commercial BaMgAl 10 O 17 :Eu 2+ blue phosphor (YiXi Electronic Technology (Shanghai) Co., Ltd.) and (Ba,Sr)Si2O4:Eu 2+The green phosphor (YiXi Electronic Technology (Shanghai) Co., Ltd.) is mixed in a mass ratio of 3:1:8 of blue powder, green powder, and red powder, and is encapsulated with a 410 nm violet chip to obtain an LED device. Similarly, the YAG:Ce in Comparative Example 4 3+ The yellow phosphor is encapsulated with a 465 nm blue LED chip to obtain an LED device. The electroluminescence performance of the above LED devices is tested using a high-precision fast spectral radiometer (HAAS-2000, EVERFINE). The results show that the LED device prepared from the phosphor of the present invention has a color rendering index as high as 93.7 and a lower color temperature of 5761K. In comparison, the color rendering index of the LED device prepared by encapsulating the commercially available YAG:Ce 3+ The yellow phosphor is only 80, and the color temperature is >6000K.

[0093] In summary, the violet-excited red phosphor prepared by the present invention can be well matched with the existing violet chips. The prepared white LED device has a high color rendering index and a low color temperature, can meet the commercial market demand, and has great development potential in the field of healthy lighting such as violet-excited white LEDs, violet-excited solar-like LEDs, and violet-excited full-spectrum LEDs.

[0094] The above description of the embodiments is for the convenience of those of ordinary skill in the art to understand and use the invention. It is obvious that those skilled in the art can easily make various modifications to these embodiments 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 all improvements and modifications made by those skilled in the art without departing from the scope of the present invention should be within the protection scope of the present invention.

Claims

1. A deep red light fluorescent material with high thermal stability, characterized in that, The fluorescent material is a La2O3-MgO-A2O5-Sm2O3 system, where A is selected from one or more combinations of Nb, Ta, or Sb; In the La2O3-MgO-A2O5-Sm2O3 system, the molar ratio of La:Mg:A:Sm is (1.9-1.99):1:1:(0.01-0.1).

2. The deep red light-emitting fluorescent material with high thermal stability according to claim 1, characterized in that, In the La2O3-MgO-A2O5-Sm2O3 system, the molar ratio of La:Mg:A:Sm is 1.99:1:1:0.01 or 1.98:1:1:0.02 or 1.97:1:1:0.

03.

3. A deep red light-emitting fluorescent material with high thermal stability according to claim 1, characterized in that, In the La2O3-MgO-A2O5-Sm2O3 system, the components in terms of mass percentage of oxides are: 52.62% ≤ La2O3 ≤ 64.95%, 6.85% ≤ MgO ≤ 8.07%, 22.60% ≤ A2O5 ≤ 44.27%, 0.30% ≤ Sm2O3 ≤ 3.49%.

4. The deep red light-emitting fluorescent material with high thermal stability according to claim 1, characterized in that, The excitation spectrum range of the fluorescent material is 365-385 nm, 400-410 nm, and 475-500 nm; Among them, the best excitation spectrum range is 400-410 nm.

5. A deep red light fluorescent material with high thermal stability according to claim 1, characterized in that The emission center wavelength of the fluorescent material is 650 nm, accompanied by multi-peak narrow-band emissions at 550-625 nm and 675-750 nm.

6. A method for preparing the deep red light-emitting fluorescent material with high thermal stability according to any one of claims 1-5, characterized in that, It includes the following steps: S1: Weigh the La source compound, Mg source compound, A source compound, and samarium source compound in proportion, and grind and mix the raw materials to obtain a mixture; S2: Subject the mixture obtained in S1 to primary sintering to obtain a precursor; S3: After secondary grinding and mixing of the precursor obtained in S2, perform secondary sintering to obtain the deep red light fluorescent material.

7. The preparation method of the deep red light fluorescent material with high thermal stability according to claim 6, characterized in that, In step S1, the La source compound, Mg source compound, A source compound, and samarium source compound are each independently selected from one or more of the corresponding metal element's simple substance, oxide, chloride, sulfide, carbonate, sulfate, phosphate, nitrate; The grinding time is 5-120 min.

8. The preparation method of the deep red light fluorescent material with high thermal stability according to claim 6, characterized in that, In step S2, the primary sintering is carried out in an air atmosphere; The temperature of the primary sintering is 200-800 °C, and the time is 5-24 h.

9. The preparation method of the deep red light fluorescent material with high thermal stability according to claim 6, characterized in that, In step S3, the secondary grinding time is 5-120 min; The secondary sintering is carried out in an inert atmosphere, and the inert atmosphere is selected from one or more of nitrogen, helium, and argon; The temperature of the secondary sintering is 1000-1700 °C, and the time is 1-24 h.

10. An LED light source is prepared from the deep red light fluorescent material with high thermal stability according to any one of claims 1-5, and is characterized in that, The LED light source is prepared by encapsulating a deep red light fluorescent material, a blue fluorescent powder, a green fluorescent powder, and a violet chip; The color rendering index of the LED light source is not less than 90.

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