A borate blue luminescent phosphor suitable for near-ultraviolet light excitation, a preparation method thereof and a warm white LED device

Abstract

The application relates to the field of luminescent materials, and discloses a borate blue luminescent powder suitable for near-ultraviolet light excitation, a preparation method of the luminescent powder, and a warm white light LED device. 8‑x B 12 O 24 F6Cl:xEu 2+ (0<=x<=0.03); the luminescent powder has strong absorption in a 350-400 nm wave band, can be effectively excited by near-ultraviolet light, and emits high-color-purity blue light with a main wavelength of 470 nm. After the luminescent powder is immersed in low-concentration hydrochloric acid for impurity removal, the luminous intensity and quantum efficiency of the luminescent powder are obviously improved. The luminescent powder keeps high-intensity emission under a high-temperature environment, and has excellent thermal stability; the luminescent powder has a low synthesis temperature, a simple process, low cost, and environmental friendliness, and is suitable for industrial production. Excellent comprehensive performance enables the luminescent powder to be mixed with other color luminescent powders, so that a warm white light LED device with high color rendering index and moderate color temperature is obtained under the driving of a near-ultraviolet light chip.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of luminescent materials, and particularly relates to a borate blue luminescent phosphor suitable for near-ultraviolet light excitation, a preparation method thereof and a warm white light LED device. BACKGROUND

[0002] Advanced lighting and backlighting devices are becoming increasingly popular worldwide. Phosphor-converted light emitting diodes (pc-LEDs) are attracting attention due to their low power consumption, long lifetime and low manufacturing cost. In the field of indoor lighting applications, warm white light emitting diodes (WLEDs) are considered to be a more competitive future light source than incandescent lamps and compact fluorescent lamps, and they have many unparalleled advantages such as high efficiency, energy saving, long lifetime and environmental reliability.

[0003] Currently, the mainstream scheme of commercial white light LEDs is to coat yellow phosphor (YAG:Ce 3+ ) on an InGaN blue chip, and white light is obtained by part of the blue light emitted by the blue chip and the yellow light emitted by the yellow phosphor excited by the blue chip. However, due to the lack of green and red components in the white light spectrum obtained by this scheme, the color rendering index is low (Ra<80), and the correlated color temperature is high (CCT>7000), which cannot meet people's pursuit of high-quality LEDs. In order to solve the problems caused by the combination of blue chips and yellow phosphor (YAG:Ce 3+ ) to produce white light, researchers began to use near-ultraviolet chips to combine red, green and blue three-primary-color phosphors to obtain white light. This scheme requires that the red, green and blue three-primary-color phosphors have strong absorption in the ultraviolet region and high-efficiency light emission in the visible region. Therefore, how to realize white light LED by exciting red, green and blue three-primary-color mixed phosphors with near-ultraviolet light has become a hot spot of research at home and abroad. Among them, the development of blue light suitable for near-ultraviolet light excitation is the key to the strategy of combining red, green and blue three-primary-color phosphors with near-ultraviolet chips to obtain white light. Therefore, the development of blue luminescent phosphor with excellent comprehensive performance has become one of the key points to obtain high-efficiency LED devices. SUMMARY

[0004] In order to solve the problems in the prior art, the purpose of the present application is to provide a borate blue luminescent phosphor suitable for near-ultraviolet light excitation, a preparation method thereof and a warm white light LED device. The phosphor has strong absorption in the near-ultraviolet region, excellent thermal stability, and can meet the high color purity blue emission of near-ultraviolet light excitation.

[0005] In order to achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0006] A borate blue luminescent phosphor suitable for near-ultraviolet light excitation has the following chemical formula:

[0007] LiNa2Sr8-x B 12 O 24 F6Cl:xEu 2+ , wherein x is Eu 2+ substituted Sr 2+ , and the molar ratio of x is in the range of 0 < x ≤ 0.03.

[0008] The application provides a preparation method of a borate blue luminescent powder suitable for near-ultraviolet light excitation, which comprises the following steps:

[0009] Mixing raw material powders of the borate blue luminescent powder suitable for near-ultraviolet light excitation to obtain a raw material mixture;

[0010] Pre-sintering the raw material mixture at 200-500 ℃ for 2-6 h, cooling to room temperature after pre-sintering, grinding into powder, mixing, and obtaining an intermediate;

[0011] Pressing the intermediate into a sheet-shaped forming body;

[0012] Primary calcining the sheet-shaped forming body, naturally cooling after primary calcination, grinding into powder, secondary calcining the obtained powder, naturally cooling after secondary calcination, and grinding into powder; the calcination conditions of the primary calcination and the secondary calcination are the same, the temperature is 650-750 ℃, the time is 4-8 h, and the atmosphere is a reducing atmosphere;

[0013] Soaking the powder obtained by secondary calcination and grinding in a hydrochloric acid solution to remove impurities, separating, washing, and drying after soaking to obtain the borate blue luminescent powder suitable for near-ultraviolet light excitation.

[0014] Preferably, the raw material of the borate blue luminescent powder comprises compounds containing Li, Na, Sr, B, F, Cl and Eu.

[0015] Preferably, the compounds comprise metal oxides, hydroxides or carbonates, and the boron-containing compound is boric acid or boron trioxide.

[0016] Preferably, when the intermediate is pressed into a sheet-shaped forming body, the intermediate is pressed into a round sheet, and the pressing pressure is 14-18 MPa.

[0017] Preferably, the reducing atmosphere is a mixed gas of H2 with a volume fraction of 5%-10% and N2 with a volume fraction of 95%-90%.

[0018] Preferably, the concentration of the hydrochloric acid solution is 0.005-0.03 mol / L.

[0019] Preferably, when the secondary calcined and ground powder is immersed in a hydrochloric acid solution to remove impurities, 3-6 g of the secondary calcined and ground powder is added to 10-20 mL of the solution.

[0020] The application also provides a warm white LED device, comprising a near-ultraviolet LED chip and blue, green and red three-primary-color phosphors arranged on the near-ultraviolet LED chip; wherein the blue phosphor is the borate blue light-emitting phosphor suitable for near-ultraviolet excitation as described above.

[0021] Preferably, the near-ultraviolet LED chip is a GaN semiconductor chip with an emission wavelength of 395 nm, the red phosphor is CaAlSiN3:Eu 2+ , and the green phosphor is (Sr, Ba)2SiO4:Eu 2+ .

[0022] The application has the following beneficial effects:

[0023] The borate blue light-emitting phosphor suitable for near-ultraviolet excitation has a wide excitation spectral range, has a strong absorption in the range of 250-410 nm, and has a strongest absorption peak in the range of 350-400 nm, so that the borate blue light-emitting phosphor can be effectively excited by near-ultraviolet light; under the excitation of near-ultraviolet light, the borate blue light-emitting phosphor suitable for near-ultraviolet excitation emits blue light with high intensity, and the emission spectrum range is 390-550 nm, and the emission main wavelength is 470 nm, so that the borate blue light-emitting phosphor is suitable for near-ultraviolet light conversion; the borate blue light-emitting phosphor suitable for near-ultraviolet excitation has excellent thermal stability (the emission intensity at 150 ℃ is as high as 89% of the emission intensity at room temperature), and is suitable for actual operation of a white LED device.

[0024] In the preparation method, the heat treatment processes of pre-sintering and twice calcination are determined according to the composition of raw materials, the temperature is relatively low, energy can be effectively saved, the process is simple, environmental protection, the product has high phase purity, and is easy for industrial production; the application provides a strategy of removing impurities by immersing the secondary calcined and ground powder in a low-concentration hydrochloric acid solution, so that the luminous intensity of the final phosphor is significantly improved (the luminous intensity is enhanced by 39% after acid treatment), and the quantum efficiency of the phosphor after acid treatment is also significantly enhanced, and the highest quantum efficiency can reach 90%.

[0025] The warm white LED device provided by the application uses the blue light-emitting phosphor, and the blue light-emitting phosphor can be used for near-ultraviolet excitation white light in the warm white LED device, so that the warm white LED device provided by the application can obtain a series of high-efficiency warm white light under the excitation of near-ultraviolet light with different currents. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1The X-ray diffraction pattern of the phosphor prepared in Example 1 of this invention;

[0027] Figure 2 The phosphor prepared in Example 1 of this invention is excited by (λ) em =470 nm) and emission (λ ex Spectrum at 370 nm (370 nm);

[0028] Figure 3 The graph shows the change in emission intensity of the phosphor prepared in Example 1 of this invention as a function of excitation wavelength.

[0029] Figure 4 The graph shows the quantum efficiency of the phosphor prepared in Example 1 of this invention as a function of excitation wavelength.

[0030] Figure 5 The graph shows the emission intensity of the phosphor prepared in Example 1 of this invention as a function of temperature (λ). ex =370 nm);

[0031] Figure 6 The electroluminescence spectrum of the white LED device fabricated in Embodiment 1 of the present invention;

[0032] Figure 7 The phosphor prepared in Example 2 of this invention is excited by (λ) em =470 nm) and emission (λ ex Spectrum at 370 nm (370 nm);

[0033] Figure 8 The phosphor prepared in Example 3 of this invention is excited by (λ) em =470 nm) and emission (λ ex Spectrum at 370 nm (370 nm);

[0034] Figure 9 The phosphor prepared in Example 4 of this invention is excited by (λ) em =470 nm) and emission (λ ex =370 nm) spectrum. Detailed Implementation

[0035] The present invention will now be described in detail with reference to the embodiments and accompanying drawings. This is merely an explanation of the present invention, and the feasible implementation methods of the present invention are not limited thereto.

[0036] This invention relates to a borate blue luminescent phosphor suitable for near-ultraviolet light excitation, the chemical formula of which is as follows:

[0037] LiNa2Sr 8-x B 12 O 24 F6Cl:xEu 2+ , where x is Eu2+ substituted Sr 2+ The molar ratio of x is in the range of 0 < x < 0.03.

[0038] The preparation method of the borate blue luminescent phosphor suitable for near-ultraviolet excitation as described above comprises the following steps:

[0039] Step (1): Accurately weigh the compounds of general formula LiNa2Sr 8-x B 12 O 24 F6Cl:xEu 2+ The compounds containing Li, Na, Sr, B, F, Cl and Eu are used as raw materials, and the raw materials are ground and mixed uniformly to obtain a raw material mixture; wherein the compounds are metal oxides, hydroxides or carbonates, and the boron-containing compounds are boric acid or diboron trioxide;

[0040] Step (2): Put the raw material mixture obtained in step (1) into a corundum crucible and place it in a box furnace for pre-sintering at 200-500°C for 2-6 hours, then cool to room temperature and grind and mix uniformly to obtain an intermediate;

[0041] Step (3): Grind the intermediate obtained in step (2) into powder and press into a round sheet under a press with a pressure of 14-18 MPa; then place the obtained round sheet in a tube furnace under the protection of a reducing atmosphere and calcine at 650-750°C for 4-8 hours, then naturally cool and grind into powder; then calcine again under the same conditions, naturally cool and grind into powder; wherein the reducing atmosphere is a mixed gas of H2 with a volume fraction of 5-10% and N2 with a volume fraction of 95-90%;

[0042] Step (4): Weigh 3-6 g of the powder obtained in step (3) and place it in a beaker containing 10-20 mL of low-concentration hydrochloric acid with a concentration of 0.005-0.03 mol / L, soak for 12-72 hours, then centrifuge and wash, then dry the moisture at 60-75°C to obtain the borate blue luminescent phosphor suitable for near-ultraviolet excitation. During centrifugal washing, the centrifuge tube size is 50 mL. When separating the soaking liquid from the powder, the centrifugal speed is 10000 r / min and the centrifugal time is 8-10 min;

[0043] The borate blue luminescent phosphor suitable for near-ultraviolet excitation is applied to a warm white LED device, which comprises a near-ultraviolet LED chip and red, green and blue phosphor layers arranged on the near-ultraviolet chip. The blue phosphor is the borate blue luminescent phosphor suitable for near-ultraviolet excitation as described above.

[0044] In the above scheme of the present application, the near-ultraviolet LED chip adopts a GaN semiconductor chip with an emission wavelength of 395 nm; typically and non-limitingly, the red phosphor is CaAlSiN3: Eu 2+ , and the green phosphor is (Sr, Ba)2SiO4: Eu 2+ .

[0045] Example 1

[0046] The preparation method of the borate blue luminescent phosphor suitable for near-ultraviolet light excitation in this example includes the following processes:

[0047] According to the stoichiometric ratio of each element in the chemical formula LiNa2Sr 7.995 B 12 O 24 F6Cl: 0.005Eu 2+ , 5 mmol NaHCO3, 24.975 mmol SrCO3, 15 mmol SrF2, 60 mmol H3BO3, and 0.0125 mmol Eu2O3 are accurately weighed. The above raw materials are ground and mixed uniformly, then loaded into a corundum crucible, and then placed in a box furnace for pre-burning. After being heated to 200℃, the temperature is kept for 6 h. After natural cooling to room temperature, the material is discharged, ground into powder, and then pressed into a round sheet under a tablet press (the pressure is set to 16 MPa). The round sheet is loaded into a corundum crucible with a cover, and then placed in a high-temperature tubular furnace in a mixed gas atmosphere of 10% H2-90% N2 (volume ratio). The temperature is raised to 650℃ for calcination, and the holding time is 8 h. After natural cooling to room temperature, the material is discharged, and then ground again. The sheet is pressed again and calcined under the same calcination conditions. After cooling, the powder is obtained. 4 g of the synthesized powder is placed in a beaker containing 15 mL of 0.01 mol / L hydrochloric acid, soaked for 48 h, and then centrifuged and washed. After drying, the near-ultraviolet light-excited blue luminescent phosphor is obtained.

[0048] Figure 1 is the X-ray diffraction pattern of the above-mentioned phosphor of this example. A small amount of impurity diffraction peak is observed in the prepared phosphor, indicating that there is a certain amount of impurity in the prepared phosphor. After treatment with low-concentration acid, the impurity diffraction peak is observed to disappear obviously, which is well matched with the standard card of LiNa2Sr8B 12 O 24 F6Cl, indicating that the treated phosphor has high phase purity. The acid treatment strategy has a good effect on removing impurities. Figure 2 is the excitation (λ em = 470 nm) and emission (λ ex = 370 nm) spectrum of the above-mentioned phosphor. From the excitation spectrum, it can be seen that the excitation wavelength of the phosphor is mainly concentrated in the near-ultraviolet region, which is consistent with the actual use of the phosphor. Figure 2It can be seen from the above that the excitation spectrum of the prepared phosphor is in the range of 250-400 nm, and the strongest absorption peak is at 370 nm, which can be effectively excited by near-ultraviolet light. The emission spectrum wavelength range is 390-550 nm, and the emission main wavelength is at 470 nm, indicating that the phosphor is suitable for near-ultraviolet excitation conversion of blue phosphor. It is also observed that the luminous intensity of the phosphor after acid treatment is significantly improved. Figure 3 is a graph of the emission intensity of the phosphor versus the excitation wavelength. It is observed that the emission intensity of the phosphor after acid treatment is significantly improved at different excitation wavelengths, and the luminous intensity of the phosphor after acid treatment at an excitation wavelength of 370 nm is improved by 39% compared with before treatment. It is indicated that the acid treatment strategy has a good effect on the luminous intensity of the phosphor. Figure 4 is a graph of the quantum efficiency of the phosphor versus the excitation wavelength. It is observed that the quantum efficiency of the phosphor after acid treatment is significantly improved at different excitation wavelengths, and the quantum efficiency of the phosphor after acid treatment at an excitation wavelength of 370 nm is as high as 90%, indicating that the acid treatment strategy has a good effect on the quantum efficiency of the phosphor. Figure 5 is a graph of the emission intensity of the phosphor versus the excitation wavelength. It is observed that the emission intensity of the phosphor after acid treatment is significantly improved at different excitation wavelengths, and the luminous intensity of the phosphor after acid treatment at an excitation wavelength of 370 nm is improved by 39% compared with before treatment. It is indicated that the acid treatment strategy has a good effect on the luminous intensity of the phosphor.

[0049] The embodiment provides a warm white LED device. The warm white LED device comprises the blue phosphor provided by the application and commercial red and green phosphors capable of being excited by near-ultraviolet light, a packaging substrate and a near-ultraviolet LED chip. The blue phosphor is the blue phosphor described in Embodiment 1, and the red phosphor is CaAlSiN3:Eu 2+ , and the green phosphor is (Sr, Ba)2SiO4:Eu 2+ . A GaN semiconductor LED chip with a light-emitting wavelength of 395 nm is used; the three primary color phosphors are mixed uniformly, and then mixed with an epoxy resin or a silicone adhesive and the like packaging material, which is coated on the LED chip, and the circuit is welded, so that a white LED light-emitting device is obtained.

[0050] Table 1 is the luminous efficiency data of the packaged white LED at different currents in the embodiment.

[0051] Table 1

[0052]

[0053] It can be seen from Table 1 that the assembled LED device has stable color output and correlated color temperature under different driving currents, and can maintain a stable color rendering index. It can be seen from Table 1 that the assembled LED device has stable color output and correlated color temperature under different driving currents, and can maintain a stable color rendering index.

[0054] The EL spectrum of the white LED device obtained in Example 1 is as follows: Figure 6 As shown, the red light region exhibits stronger luminous intensity. Table 1 also presents the luminous efficacy data of the fabricated LED under different currents. The fabricated LED device displays a high color rendering index and a moderate color temperature, meeting the demand for high-quality LEDs.

[0055] Example 2

[0056] The preparation method of borate blue luminescent phosphor suitable for near-ultraviolet light excitation in this embodiment includes the following steps:

[0057] According to the chemical formula LiNa2Sr 7.99 B 12 O 24 F6Cl: 0.01Eu 2+ The stoichiometric ratios of the elements in the sample were accurately measured as follows: 2.5 mmol Li₂CO₃, 5 mmol NaCl, 5 mmol NaHCO₃, 24.95 mmol SrCO₃, 15 mmol SrF₂, 60 mmol H₃BO₃, and 0.025 mmol Eu₂O₃. The above raw materials were ground and mixed thoroughly, then placed in an alumina crucible and pre-fired in a box furnace. The temperature was raised to 500℃ and held for 2 hours. After natural cooling to room temperature, the material was discharged, ground into powder, and pressed into tablets using a tablet press (pressure set to 14 MPa). The tablets were then placed in a covered alumina crucible and placed in a high-temperature tube furnace with a mixed atmosphere of 5% H₂-95% N₂ (volume ratio). The temperature was raised to 750℃ and held for 4 hours. After natural cooling to room temperature, the material was discharged, pressed into tablets again, and calcined again under the same conditions. After cooling, the tablets were ground into powder. Weigh 3 g of the synthesized powder and place it in a beaker containing 18 mL of 0.005 mol / L hydrochloric acid. After soaking for 72 h, centrifuge, wash, and dry to obtain the near-ultraviolet light-excited blue phosphor.

[0058] like Figure 7 As shown, the excitation spectrum of the phosphor sample in this embodiment has a wavelength range of 250–400 nm, with the strongest absorption peak at 370 nm, indicating that it can be effectively excited by near-ultraviolet light. The emission spectrum has a wavelength range of 390–550 nm, with the dominant emission wavelength at 470 nm, indicating that this phosphor is suitable for near-ultraviolet excitation and conversion of blue phosphors.

[0059] Example 3

[0060] The preparation method of borate blue luminescent phosphor suitable for near-ultraviolet light excitation in this embodiment includes the following steps:

[0061] According to the chemical formula LiNa2Sr 7.985 B12 O 24 F6Cl: 0.015Eu 2+ The stoichiometric ratios of the elements in the sample were accurately measured as follows: 2.5 mmol Li₂CO₃, 5 mmol NaCl, 5 mmol NaHCO₃, 24.925 mmol SrCO₃, 15 mmol SrF₂, 60 mmol H₃BO₃, and 0.0375 mmol Eu₂O₃. The above raw materials were ground and mixed thoroughly, then placed in an alumina crucible and pre-fired in a box furnace. The temperature was raised to 500℃ and held for 6 hours. After natural cooling to room temperature, the material was discharged, ground into powder, and pressed into tablets using a tablet press (pressure set to 16 MPa). The tablets were then placed in an alumina crucible with an alumina boat and placed in a high-temperature tube furnace with a mixed atmosphere of 10% H₂-90% N₂ (volume ratio). The temperature was raised to 700℃ and held for 6 hours. After natural cooling to room temperature, the material was discharged, pressed into tablets again, and calcined again under the same conditions. After cooling, the tablets were ground into powder. Weigh 4g of the synthesized powder and place it in a beaker containing 15mL of 0.02mol / L hydrochloric acid. After soaking for 24h, centrifuge, wash, and dry to obtain the near-ultraviolet light-excited blue phosphor.

[0062] like Figure 8 As shown, the excitation spectrum of the phosphor sample in this embodiment has a wavelength range of 250–400 nm, with the strongest absorption peak at 370 nm, indicating that it can be effectively excited by near-ultraviolet light. The emission spectrum has a wavelength range of 390–550 nm, with the dominant emission wavelength at 470 nm, indicating that this phosphor is suitable for near-ultraviolet excitation and conversion of blue phosphors.

[0063] Example 4

[0064] The preparation method of borate blue luminescent phosphor suitable for near-ultraviolet light excitation in this embodiment includes the following steps:

[0065] According to the chemical formula LiNa2Sr 7.97 B 12 O 24 F6Cl: 0.03Eu 2+The stoichiometric ratios of the elements in the sample were accurately measured as follows: 2.5 mmol Li₂CO₃, 5 mmol NaCl, 5 mmol NaHCO₃, 24.85 mmol SrCO₃, 15 mmol SrF₂, 60 mmol H₃BO₃, and 0.005 mmol Eu₂O₃. The above raw materials were ground and mixed thoroughly, then placed in an alumina crucible and pre-fired in a box furnace. The temperature was raised to 400℃ and held for 4 hours. After natural cooling to room temperature, the material was discharged, ground into powder, and pressed into tablets using a tablet press (pressure set to 18 MPa). The tablets were then placed in an alumina crucible with an alumina boat and placed in a high-temperature tube furnace with a mixed atmosphere of 7% H₂-93% N₂ (volume ratio). The temperature was raised to 700℃ and held for 4 hours. After natural cooling to room temperature, the material was discharged, pressed into tablets again, and calcined under the same conditions. After cooling, the tablets were ground into powder. Weigh 6g of the synthesized powder and place it in a beaker containing 20mL of 0.03 mol / L hydrochloric acid. After soaking for 12h, centrifuge, wash, and dry to obtain the near-ultraviolet light-excited blue phosphor.

[0066] like Figure 9 As shown, the excitation spectrum of the phosphor sample in this embodiment has a wavelength range of 250–400 nm, with the strongest absorption peak at 370 nm, indicating that it can be effectively excited by near-ultraviolet light. The emission spectrum has a wavelength range of 390–550 nm, with the dominant emission wavelength at 470 nm, indicating that this phosphor is suitable for near-ultraviolet excitation and conversion of blue phosphors.

[0067] The above embodiments are merely illustrative of the present invention and are not intended to limit the present invention. Those skilled in the art can make modifications and improvements based on the technical solutions of the present invention, but such modifications and improvements do not depart from the essential scope of the embodiments of the present invention and all fall within the protection scope of the technical solutions of the present invention.

Claims

1. A borate blue emitting phosphor suitable for near ultraviolet light excitation, characterized in that, The chemical formula is as follows: LiNa2Sr 8-x B 12 O 24 F6Cl:xEu 2+ , wherein x is Eu 2+ substituted Sr 2+ , and the molar ratio of x is in the range of 0 < x ≤ 0.

03.

2. The method for preparing borate blue luminescent phosphor suitable for near-ultraviolet excitation according to claim 1, characterized in that, The process comprises the following steps: Mixing raw material powders of borate blue luminescent phosphor suitable for near-ultraviolet light excitation to obtain a raw material mixture; Pre-sintering the raw material mixture at 200-500 DEG C for 2-6 hours, cooling to room temperature after pre-sintering, grinding into powder, mixing, and obtaining an intermediate; Pressing the intermediate into a sheet-shaped forming body; Once calcining the sheet-shaped forming body, naturally cooling after once calcining, grinding into powder, twice calcining the ground powder, naturally cooling after twice calcining, and grinding into powder; the calcining conditions of once calcining and twice calcining are the same, the temperature during calcining is 650-750 DEG C, the time is 4-8 hours, and the atmosphere is a reducing atmosphere; Soaking the powder obtained by twice calcining and grinding in a hydrochloric acid solution to remove impurities, separating, washing, and drying after soaking to obtain the borate blue luminescent phosphor suitable for near-ultraviolet light excitation.

3. The method for preparing a borate blue luminescent phosphor suitable for near-ultraviolet light excitation as described in claim 2, characterized in that, The raw material of the borate blue luminescent phosphor comprises compounds containing Li, Na, Sr, B, F, Cl, and Eu elements.

4. The method for preparing a borate blue luminescent phosphor suitable for near-ultraviolet light excitation as described in claim 3, characterized in that, The boron-containing compound is boric acid or boron trioxide.

5. The method for preparing a borate blue luminescent phosphor suitable for near-ultraviolet light excitation as described in claim 2, characterized in that, When the intermediate is pressed into a sheet-shaped forming body, the pressing is performed into a round sheet, and the pressing pressure is 14-18 MPa.

6. The method for preparing a borate blue luminescent phosphor suitable for near-ultraviolet light excitation as described in claim 2, characterized in that, The reducing atmosphere is a mixed gas of H2 with a volume fraction of 5%-10% and N2 with a volume fraction of 95%-90%.

7. The method for preparing a borate blue luminescent phosphor suitable for near-ultraviolet light excitation as described in claim 2, characterized in that, The concentration of the hydrochloric acid solution is 0.005-0.03 mol / L.

8. The method for preparing a borate blue luminescent phosphor suitable for near-ultraviolet light excitation as described in claim 7, characterized in that, When the powder obtained by twice calcining and grinding is soaked in a hydrochloric acid solution to remove impurities, 3-6 g of the powder obtained by twice calcining and grinding is added into 10-20 mL of the hydrochloric acid solution.

9. A warm white LED device, characterized in that The near-ultraviolet light LED chip and the blue, green, and red three-primary-color luminescent phosphor arranged on the near-ultraviolet light LED chip; wherein the blue luminescent phosphor is the borate blue luminescent phosphor suitable for near-ultraviolet light excitation according to claim 1.

10. A warm white LED device as defined in claim 9, wherein The near-ultraviolet light LED chip adopts GaN semiconductor chip with an emission wavelength of 395 nm, the red fluorescent powder adopts CaAlSiN3:Eu 2+ , and the green fluorescent powder adopts (Sr, Ba)2SiO4:Eu 2+ .

Images