365nm excitation high thermal stability blue-violet phosphor and preparation method thereof

Abstract

The application discloses a 365nm-excited high-stability blue-violet fluorescent powder and a preparation method thereof, and the molecular formula of the fluorescent powder is Ca4MO(BO3)3:xCe 3+ In the formula, M represents Sc or Ga, and 0.25%<=x<=2%. The fluorescent powder is prepared by a high-temperature solid-phase method, and is mixed according to the material ratio, is ground, is placed in a muffle furnace, is pre-calcined at 300-600 DEG C for 2-10 hours under an air atmosphere, is placed in a tube furnace, and is calcined at 900-1100 DEG C for 4-24 hours under a reducing atmosphere. The fluorescent powder has high color purity and high thermal stability, and can be effectively matched with other fluorescent powders and applied to a light-emitting diode (LED) for illumination, so that the color rendering index of the LED is improved, the luminous efficiency is improved, and the fluorescent powder has a wide application prospect.

Description

Technical Field

[0001] This invention belongs to the field of luminescent materials technology, specifically relating to a high-efficiency blue phosphor and its preparation method. Background Technology

[0002] With the continuous improvement of living standards, people have increasingly higher requirements for lighting quality. High-quality, full-spectrum lighting has become a new trend in "healthy and green lighting" worldwide. Full-spectrum white LEDs refer to LEDs with a wide spectral coverage (380–780 nm), close to the visible light spectrum of sunlight, good spectral continuity, no obvious peaks and troughs in the spectral distribution, excellent color rendering index, and strong ability to reproduce the colors of objects. Full-spectrum white LEDs have wide applications in operating rooms, museums, high-end stages, health lighting, plant growth, and other fields.

[0003] Currently, there are two main ways to achieve full-spectrum illumination. One is to use blue light excitation to achieve full-spectrum illumination by adding green and red phosphors to the LED. The advantage of this combination is that it can display the true color of the illuminated object with a high color rendering index. However, the red component is a double-edged sword; it also reduces the luminous efficiency of the device. Some of the emission wavelengths of the red phosphor exceed 650nm. The human eye is very insensitive to light from this region, thus reducing the efficiency of WLED devices. Meanwhile, the blue light component remains relatively strong.

[0004] Secondly, a full-spectrum approach using violet light excitation employs a 365-395nm chip combined with multi-color phosphors such as blue, green, and red. This combination performs better in suppressing blue light and supplementing cyan, with a spectral shape closer to the solar spectrum. It also supplements the short-wave violet portion and even includes a small amount of long-wave ultraviolet light. This approach effectively improves the color rendering index and reduces the harmful effects of blue light, but the photoelectric conversion efficiency is not high, and the reabsorption effect between different phosphors is severe. Recent studies have shown that blue-violet light (380-420nm) is beneficial and has a certain promoting effect on visual development. Therefore, supplementing the visible blue-violet light band of 380-420nm and reducing the harmful blue light peak of 430-455nm is the packaging solution currently used by full-spectrum lighting manufacturers both domestically and internationally. Summary of the Invention

[0005] The purpose of this invention is to provide a high thermal stability blue-violet phosphor excited at 365nm, and to provide a method for preparing the phosphor.

[0006] To achieve the above objectives, the blue-violet phosphor used in this invention has the molecular formula Ca4MO(BO3)3:xCe 3+ In the formula, M represents Sc or Ga, and 0.25% ≤ x ≤ 2%, preferably 0.5% ≤ x ≤ 1.5%.

[0007] The preparation method of the blue-violet phosphor of the present invention is as follows: The calcium source, boron source, cerium oxide source, scandium source or gallium source, boron source, and cerium oxide are added to a mortar and ground until uniformly mixed. The mixture is then placed in a muffle furnace and pre-calcined at 300–600°C for 2–10 hours in air. After further grinding, the mixture is placed in a tube furnace and calcined at 900–1100°C for 8–24 hours in a reducing atmosphere. The calcined product is then ground, washed sequentially with distilled water at 60–80°C and ethanol, and dried to obtain the blue-violet phosphor.

[0008] The calcium source mentioned above is any one of calcium carbonate, calcium chloride, calcium oxide, and calcium sulfate; the scandium source is any one of scandium oxide, scandium acetate, nitric acid, and scandium carbonate; the gallium source is gallium trioxide; and the boron source is any one of boric acid, boron oxide, and ammonium borate.

[0009] In the above preparation method, it is preferable to pre-calcine at 350–500°C for 3–6 hours in an air atmosphere.

[0010] In the above preparation method, it is preferable to calcine at 900–1100°C for 10–24 hours under a reducing atmosphere.

[0011] In the above preparation method, the reducing atmosphere is a mixture of hydrogen and nitrogen or argon, and the volume ratio of hydrogen to nitrogen in the mixture is 1:9.

[0012] In the above preparation method, it is preferable to control the flow rate of the mixed gas to be 20-40 mL / min, and more preferably to control the flow rate of the mixed gas to be 25-35 mL / min.

[0013] The beneficial effects of this invention are as follows:

[0014] This invention uses Ca4MO(BO3)3 (M = Sc, Ga) as a matrix to prepare a Ce-based... 3+ This novel high-efficiency blue-violet phosphor, which acts as an activator, has high color purity and good thermal stability. It can be effectively combined with other phosphors and applied in light-emitting diodes (LEDs) for lighting, thereby improving the color rendering index of LEDs and showing broad application prospects. Attached Figure Description

[0015] Figure 1 It is the Ca4ScO(BO3):1%Ce prepared in Example 1 3+ XRD pattern of phosphor.

[0016] Figure 2 It is the Ca4ScO(BO3):1%Ce prepared in Example 1 3+Photoluminescence spectrum of phosphor (red line is excitation spectrum, black line is emission spectrum).

[0017] Figure 3 It is the Ca4GaO(BO3):1%Ce prepared in Example 2 3+ XRD pattern of phosphor.

[0018] Figure 4 It is the Ca4GaO(BO3):1%Ce prepared in Example 2 3+ Photoluminescence spectrum of phosphor (red line is excitation spectrum, black line is emission spectrum).

[0019] Figure 5 It is the Ca4GaO(BO3):0.5%Ce prepared in Example 3. 3+ XRD pattern of phosphor.

[0020] Figure 6 It is the Ca4GaO(BO3):0.5%Ce prepared in Example 3. 3+ Photoluminescence spectrum of phosphor (red line is excitation spectrum, black line is emission spectrum). Detailed Implementation

[0021] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments, but the scope of protection of the present invention is not limited to these embodiments.

[0022] Example 1

[0023] Weigh out 0.4003 g (4 mmol) of CaCO3, 0.0689 g (0.5 mmol) of Sc2O3, 0.1855 g (3 mmol) of H3BO3, and 0.0017 g (0.01 mmol) of CeO2. Mix thoroughly and grind in an agate mortar for 30 minutes. Then, place the ground sample into an alumina crucible and place the alumina crucible in a muffle furnace. Pre-calcine at 450°C for 4 hours in air. After pre-calcine, remove the sample, continue grinding, and place it back into the alumina crucible. Then, place the alumina crucible in a tube furnace and calcine at 1100°C for 12 hours in a reducing atmosphere (hydrogen to nitrogen mixture with a volume ratio of 1:9 and a flow rate of 25 mL / min). After calcination, remove the sample and allow it to cool slowly to room temperature. Grind thoroughly in an agate mortar for 20 minutes, wash successively with distilled water at 60°C and ethanol, and dry at 80°C to obtain Ca4ScB3O. 10 1% Ce 3+ Fluorescent powder.

[0024] The prepared phosphor was tested using a DX-2700BH powder X-ray diffractometer from Dandong Haoyuan Instrument Co., Ltd. The test conditions were: CuKα radiation, voltage of 40KV, current of 30mA, scanning range of 5° to 70°, scanning speed of 10° / min, and step size of 0.02°. The luminescence properties were tested using a Hitachi F-7100 fluorescence spectrometer, and the quantum yield was then tested using a Hamamatsu C9920-02G quantum yield measurement system from Japan.

[0025] Depend on Figure 1 It can be seen that the obtained product Ca4ScB3O 10 1% Ce 3+ All diffraction peaks are associated with the isomorphic substance Ca4YB3O 10 The standard diffraction peaks of (PDF#50-0403) correspond one-to-one, indicating that the target product in pure phase has been synthesized.

[0026] Depend on Figure 2 It can be seen that the prepared phosphor emits a peak at 420 nm under 365 nm excitation light, which is blue-violet light, and has a color purity of 90.5%. It also has high thermal stability, with a luminous intensity at 150 °C that is 85.6% of that at room temperature and a quantum yield of 15.9%. It is expected to be applied to full-spectrum lighting LEDs excited by near-ultraviolet light.

[0027] Example 2

[0028] Weigh out 0.4003 g (4 mmol) of CaCO3, 0.0937 g (0.5 mmol) of Ga2O3, 0.1855 g (3 mmol) of H3BO3, and 0.0017 g (0.01 mmol) of CeO2. Mix thoroughly and grind in an agate mortar for 30 minutes. Then, place the ground sample into an alumina crucible and place the alumina crucible in a muffle furnace. Pre-calcine at 450°C for 4 hours in air atmosphere. After pre-calcine, remove the sample, continue grinding, and place it back into the alumina crucible. Then, place the alumina crucible in a tube furnace and calcine at 1000°C for 12 hours in a reducing atmosphere. The reducing atmosphere is a mixture of hydrogen and nitrogen in a volume ratio of 1:9, with a flow rate of 25 mL / min. After calcination, remove the sample and allow it to cool slowly to room temperature. Grind thoroughly in an agate mortar for 20 minutes, wash successively with distilled water at 60°C and ethanol, and dry at 80°C to obtain Ca4GaB3O. 10 1% Ce 3+ Fluorescent powder.

[0029] Depend on Figure 3 It can be seen that the obtained product Ca4GaB3O 10 1% Ce 3+ All diffraction peaks are associated with the isomorphic substance Ca4YB3O 10The standard diffraction peaks of (PDF#50-0403) correspond one-to-one, indicating that the target product in pure phase has been synthesized.

[0030] Depend on Figure 4 As can be seen, the prepared phosphor emits a peak at 395 nm under 365 nm excitation light, which is blue-violet light, and the color purity is 97.1%. It has very high thermal stability, with a luminous intensity at 150 °C that is 102.3% of that at room temperature and a quantum yield of 88.5%, making it suitable for use in near-ultraviolet excited full-spectrum LEDs.

[0031] Example 3

[0032] Weigh out 0.4103 g (4.1 mmol) of CaCO3, 0.0937 g (0.5 mmol) of Ga2O3, 0.2164 g (3.5 mmol) of H3BO3, and 0.0008 g (0.005 mmol) of CeO2. Mix thoroughly and grind in an agate mortar for 30 minutes. Then, place the ground sample into an alumina crucible and place the alumina crucible in a muffle furnace. Pre-calcine at 450°C for 4 hours in air atmosphere. After pre-calcination, remove the sample, continue grinding, and place it back into the alumina crucible. Then, place the alumina crucible in a tube furnace and calcine at 1050°C for 12 hours in a reducing atmosphere (hydrogen to nitrogen mixture with a volume ratio of 1:9 and a flow rate of 25 mL / min). After calcination, remove the sample and allow it to cool slowly to room temperature. Grind thoroughly in an agate mortar for 20 minutes, wash successively with 60°C distilled water and ethanol, and dry at 80°C. 10 0.5% Ce 3+ Fluorescent powder.

[0033] Depend on Figure 5 It can be seen that the obtained product Ca4GaB3O 10 0.5% Ce 3+ All diffraction peaks are associated with the isomorphic substance Ca4YB3O 10 The standard diffraction peaks of (PDF#50-0403) correspond one-to-one, indicating that the target product in pure phase has been synthesized.

[0034] Depend on Figure 6 As can be seen, the prepared phosphor emits a peak at 395 nm under 365 nm excitation light, which is blue-violet light, and the color purity is 98.1%. It has very high thermal stability, with a luminous intensity of 100.5% at 150 °C compared to room temperature, and a quantum yield of 80%, making it suitable for use in near-ultraviolet excited full-spectrum LEDs.

Claims

1. A highly stable blue-violet phosphor excited at 365nm, characterized in that: The fluorescent powder has a molecular formula of Ca4MO(BO3)3: x Ce 3+ wherein M represents Sc or Ga, and 0.25%≤x≤2%.

2. The blue-violet phosphor according to claim 1, characterized in that: In the molecular formula, 0.5% ≤ x ≤ 1.5%.

3. A method for preparing the blue-violet phosphor according to claim 1, characterized in that: According to the molar ratio of calcium, scandium or gallium, boron and cerium oxide of 3.9-4.1:1:2.9-3.5:0.0025-0.02, calcium source, boron source, cerium oxide and scandium source or gallium source are added to a mortar, ground and mixed evenly, and then placed in a muffle furnace and pre-calcined at 300-600℃ for 2-10 hours in air atmosphere. Then, it is taken out and ground again, and then placed in a tube furnace and calcined at 900-1100℃ for 8-24 hours in reducing atmosphere. After grinding, the calcined product is washed with distilled water at 60-80℃ and ethanol in sequence, and then dried to obtain blue-purple phosphor. The calcium source is any one of calcium carbonate, calcium oxalate, calcium oxide, and calcium sulfate; The scandium source is any one of scandium oxide, scandium acetate, scandium nitrate, and scandium carbonate; The gallium source is gallium trioxide; The boron source is any one of boric acid, boron oxide, or ammonium borate.

4. The method for preparing blue-violet phosphor according to claim 3, characterized in that: Pre-calcining at 350–500°C for 3–6 hours in air atmosphere.

5. The method for preparing blue-violet phosphor according to claim 3, characterized in that: Calcination at 900–1100℃ for 10–24 hours under a reducing atmosphere.

6. The method for preparing blue-violet phosphor according to claim 3 or 4, characterized in that: The reducing atmosphere is a mixture of hydrogen and nitrogen, wherein the volume ratio of hydrogen to nitrogen in the mixture is 1:

9.

7. The method for preparing the blue-violet phosphor according to claim 6, characterized in that: The flow rate of the mixed gas is controlled at 20–40 mL / min.

8. The method for preparing the blue-violet phosphor according to claim 6, characterized in that: The flow rate of the mixed gas is controlled at 25–35 mL / min.

Images