A cyan phosphate fluorescent material and its preparation method and application

Abstract

The invention discloses a cyan phosphate fluorescent material and a preparation method and application thereof, which belongs to the technical field of fluorescent materials. The chemical general formula of the cyan phosphate fluorescent material is Ba 5‑ 5x Eu 5x P6O 20 , wherein 0.5%≤x≤1.5%; the preparation method of the cyan phosphate fluorescent material comprises the following steps: weighing raw materials according to the molar ratio of each element in the chemical formula Ba:Eu:P=(5‑5x):5x:6; wherein the raw materials include a Ba-containing compound, an Eu-containing compound and a P-containing compound; adding the weighed raw materials to a dispersant for full grinding, grinding until the dispersant volatilizes, and obtaining a uniform white powder; in a reducing atmosphere, calcining the ground white powder, and then cooling to obtain the cyan phosphate fluorescent material. The cyan phosphate fluorescent material provided by the present invention emits cyan light with a central wavelength of 459nm, has high luminous intensity, and has a wide cyan light emission spectrum range compared with the prior art, which has significant advantages in improving spectral continuity and color rendering index.

Description

Technical Field

[0001] The invention relates to the technical field of fluorescent materials, in particular to a cyan phosphate fluorescent material and a preparation method and application thereof. Background Art

[0002] At the end of the 19th century, Edison invented the electric light, which changed the history of human lighting for the first time. Although the luminous efficiency of incandescent lamps can reach 15-25 lumens / watt, its energy conversion efficiency is only 5%, and the remaining 95% of energy is lost in the form of heat. In the mid-20th century, fluorescent lamps, halogen lamps and other lighting equipment came out one after another, raising the luminous efficiency to 61-100 lumens / watt, but its energy conversion efficiency is still only 25%. With the increasing prominence of global warming, energy crisis and environmental pollution, more efficient, energy-saving, environmentally friendly and long-life lighting sources have become the goal that people are constantly pursuing. In the early 1990s, Isamu Akasaki, Hiroshi Amano and Shuji Nakamura obtained the first blue light from semiconductors, making white light-emitting diodes (WLEDs) possible, and at the same time opening a new revolution in the history of human lighting. The efficiency of WLEDs is 4 times that of traditional fluorescent lamps and nearly 20 times that of incandescent lamps, and the life span can reach 100,000 hours, while that of fluorescent lamps is one-tenth and that of incandescent lamps is one-hundredth. The emergence of WLEDs is a common need for the world to advocate and participate in the development of energy conservation and environmental protection. It is an inevitable trend for WLEDs, which have unique advantages in energy conservation, environmental protection, and long life, to replace incandescent and fluorescent lamps with high energy consumption.

[0003] At present, the most widely used WLED technology in the world is the yellow fluorescent material (such as the patented technology of Nichia Chemical Company of Japan (Y 1-a G a )3(Al 1-b Ga b )5O 12 :Ce 3+ , referred to as YAG:Ce 3+) is achieved by combining a blue LED chip. Although this method can obtain an efficient WLED light source, the light source lacks red (600nm or longer wavelength) components, so it has disadvantages such as low color rendering index, high color temperature (>5500K) and severe light decay at high temperature, which makes it difficult to meet the needs of "warm white light" for general lighting. The three-primary color fluorescent material excited by the (near) ultraviolet chip can effectively solve this problem and obtain WLEDs with high color rendering index and low color temperature. It is considered to be the most promising solid-state light source device for achieving "healthy lighting". However, this combination also has its limitations, that is, there is a so-called "cyan gap" in the emission spectrum, which hinders the further improvement of the color rendering index (CRI). Therefore, in order to achieve full-spectrum WLEDs with high color rendering index, it is necessary to explore new broadband cyan luminescent materials to fill the cyan gap. As one of the components of full-spectrum WLEDs, broadband cyan fluorescent materials with high efficiency and excellent thermal stability are one of the guarantees for obtaining "full-spectrum lighting". Therefore, the development of high-performance broadband cyan fluorescent materials will help to achieve substantial progress in the healthy lighting of WLEDs.

[0004] Among the many luminescent ions, Eu 2+ It is an excellent activator due to its controllable emission color and high quantum yield caused by 4f-5d spin electronic transition. 2+ Active fluorescent materials include commercial blue fluorescent material BaMgAl 10 O 17 :Eu 2+ (BAM:Eu 2+ ), commercial green fluorescent material (Ba, Sr)2SiO4:Eu 2+ , commercial red fluorescent material CaAlSiN3:Eu 2+ Therefore, by designing a suitable crystal field environment, we can obtain 2+ Activated high-efficiency cyan fluorescent materials are feasible.

[0005] However, the existing Eu 2+ The activated cyan fluorescent material has low luminescence efficiency, poor thermal stability, and narrow half-peak width. After repeated use, the luminescence center of the material is easy to shift from Eu to 2+ Oxidized to Eu 3+ , which leads to a sharp drop in the luminous efficiency of the material, which limits its application in light-emitting devices. Therefore, it is urgent to develop broadband cyan fluorescent materials that can be excited by ultraviolet light with high efficiency and excellent thermal stability. Summary of the invention

[0006] The object of the present invention is to provide a method for preparing a cyan phosphate fluorescent material to solve the problems raised in the above background technology.

[0007] To achieve the above objectives, the embodiments of the present invention provide the following technical solutions:

[0008] A cyan phosphate fluorescent material, whose general chemical formula is Ba 5-5x Eu 5x P6O 20 , wherein 0.5%≤x≤1.5%; the preparation method of the cyan phosphate fluorescent material comprises the following steps:

[0009] Weigh the raw materials according to the molar ratio of each element in the chemical formula Ba:Eu:P=(5-5x):5x:6; wherein the raw materials include a Ba-containing compound, a Eu-containing compound and a P-containing compound;

[0010] Add the weighed raw materials to the dispersant and grind them thoroughly until the dispersant evaporates to obtain a uniform white powder;

[0011] The ground white powder is calcined in a reducing atmosphere and then cooled to obtain the cyan phosphate fluorescent material.

[0012] Preferably, the Ba-containing compound is BaO and / or BaCO3.

[0013] Preferably, the Eu-containing compound is one or more of Eu2O3, Eu(OH)3, and Eu2(CO)3.

[0014] Preferably, the P-containing compound is one or more of NH4H2PO4, (NH4)2HPO4.

[0015] Preferably, the dispersant is anhydrous ethanol.

[0016] Preferably, the calcination temperature is 700-800°C.

[0017] Another object of the embodiment of the present invention is to provide a cyan phosphate fluorescent material prepared by the above preparation method.

[0018] Another object of an embodiment of the present invention is to provide an application of the above-mentioned cyan phosphate fluorescent material in a light-emitting device.

[0019] Preferably, the light emitting device is a white light emitting diode lamp.

[0020] The preparation method of the cyan phosphate fluorescent material provided in the embodiment of the present invention adopts abundant raw material resources, the preparation method is simple and easy, the physicochemical stability is good, the fluorescence lifetime is ideal, and it is green and pollution-free. The prepared cyan phosphate fluorescent material can be used as an ultraviolet light chip for excitation in full-spectrum WLEDs devices, which can improve the color rendering index of WLEDs and has strong applicability. In addition, the cyan phosphate fluorescent material has high luminous brightness and is suitable for fluorescent materials for semiconductor lighting.

[0021] The cyan phosphate fluorescent material Ba provided by the embodiment of the present invention 5-5x Eu 5x P6O 20 , in the chemical formula Ba 2+ Ions can be 2+ ion substitution, and with the Eu 2+ Ions gradually replace Ba 2+ ions in the process of concentration quenching. The cyan phosphate fluorescent material provided in the embodiment of the present invention has ultra-wideband cyan emission under ultraviolet light excitation, with an emission peak at 459nm and a half-width of 174nm, which can cover the cyan gap of the spectrum. The excitation band of the cyan phosphate fluorescent material extends from 250nm to 400nm, reaches maximum excitation at 350nm, can be effectively excited by ultraviolet light, and has an internal quantum efficiency of 54.2%. In addition, this series of fluorescent materials has relatively excellent thermal stability. At 145°C, it can still maintain about 87.5% of the room temperature emission intensity, which meets the needs of practical applications and can be used as a high-efficiency cyan fluorescent material for indoor healthy lighting full-spectrum WLEDs. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 XRD patterns of the materials prepared in Examples 1-5 and Comparative Example 1;

[0023] Figure 2 This is the excitation emission spectrum of the material prepared in Example 3;

[0024] Figure 3 This is the excitation spectrum of the material prepared in Example 1-5 under 459nm monitoring;

[0025] Figure 4 This is the emission spectrum of the material prepared in Example 1-5 under 350nm excitation;

[0026] Figure 5 This is the CIE color coordinate diagram of the material prepared in Example 3;

[0027] Figure 6 This is a graph of the quantum efficiency of the material prepared in Example 3;

[0028] Figure 7 This is the temperature-dependent emission spectrum of the material prepared in Example 3. DETAILED DESCRIPTION

[0029] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] In one embodiment of the present invention, a cyan phosphate fluorescent material is provided, whose chemical formula is Ba 5- 5x Eu 5x P6O 20 , wherein 0.5%≤x≤1.5%; the preparation method of the cyan phosphate fluorescent material comprises the following steps:

[0031] S1. Weigh raw materials according to the molar ratio of each element in the chemical formula Ba:Eu:P=(5-5x):5x:6; wherein the raw materials include a Ba-containing compound, a Eu-containing compound and a P-containing compound;

[0032] S2. Add the weighed raw materials to the dispersant and grind them thoroughly until the dispersant evaporates to obtain a uniform white powder;

[0033] S3. In a reducing atmosphere, calcining the ground white powder, and then cooling it to obtain a cyan phosphate fluorescent material.

[0034] In a preferred embodiment of the present invention, the Ba-containing compound is BaO and / or BaCO3, preferably BaCO3.

[0035] In a preferred embodiment of the present invention, the Eu-containing compound is one or more of Eu2O3, Eu(OH)3, Eu2(CO)3, preferably Eu2O3.

[0036] In a preferred embodiment of the present invention, the P-containing compound is one or more of NH4H2PO4, (NH4)2HPO4, preferably NH4H2PO4.

[0037] In a preferred embodiment of the present invention, the dispersant is anhydrous ethanol.

[0038] In a preferred embodiment of the present invention, the calcination temperature is 700-800° C. and the calcination time is 6-10 h.

[0039] In another embodiment of the present invention, there is provided an application of the above-mentioned cyan phosphate fluorescent material in a light-emitting device; specifically, the light-emitting device is a white light emitting diode lamp (WLEDs).

[0040] The cyan phosphate fluorescent material provided in the embodiment of the present invention is Eu 2+ The quantum efficiency of the activated cyan fluorescent material reaches more than 50%, and the half-peak width reaches 174nm; the cyan phosphate fluorescent material can still maintain about 87.5% of the room temperature emission intensity at 145°C.

[0041] In the embodiment of the present invention, Ba5P6O is selected 20 As the matrix, Eu 2+ As the activator ion, a ultra-wideband cyan light emitting luminescent material is prepared by a traditional high-temperature solid-phase method to eliminate the "cyan gap" phenomenon. The emission peak range of the material covers 250-400nm, and the half-peak width is 174nm, which makes up for the cyan light loss of traditional fluorescent materials at 480-520nm. In addition, the embodiment of the present invention uses a high-temperature solid-phase method to synthesize the above-mentioned material. The prepared material powder has excellent grain growth quality, few surface defects, and the product is loose and easy to crush, easy to expand the proportion of mass production, and will not affect its luminescence performance.

[0042] The following embodiments are some specific implementation cases of the present invention in practical applications, but are not limited thereto.

[0043] Example 1: This example provides a cyan phosphate fluorescent material, whose chemical structure is Ba 5- 5x Eu 5x P6O 20 (x=0.5%); Specifically, the preparation method of the material comprises the following steps:

[0044] (1) According to the molar ratio of each element in the above chemical structure, Ba:Eu:P=(5-5x):5x:6, x=0.5%, weigh the raw materials BaCO3, Eu2O3, and NH4H2PO4;

[0045] (2) Put the weighed raw materials into an agate mortar, add an appropriate amount of anhydrous ethanol as a dispersant and grind them thoroughly for 30 minutes until the anhydrous ethanol evaporates completely to obtain a uniform white powder;

[0046] (3) The ground white powder is placed in an alumina crucible, and the alumina crucible is placed in a muffle furnace at 750° C. in a reducing atmosphere for calcination for 8 h, followed by cooling and slowly cooling to room temperature to obtain a cyan phosphate fluorescent material.

[0047] Example 2: This example provides a cyan phosphate fluorescent material, whose chemical structure is Ba5- 5x Eu 5x P6O 20 (x=0.75%); Specifically, the preparation method of the material comprises the following steps:

[0048] (1) According to the molar ratio of each element in the above chemical structure, Ba:Eu:P=(5-5x):5x:6, x=0.75%, weigh the raw materials BaCO3, Eu2O3, and NH4H2PO4;

[0049] (2) Put the weighed raw materials into an agate mortar, add an appropriate amount of anhydrous ethanol as a dispersant and grind them thoroughly for 30 minutes until the anhydrous ethanol evaporates completely to obtain a uniform white powder;

[0050] (3) The ground white powder is placed in an alumina crucible, and the alumina crucible is placed in a muffle furnace at 750° C. in a reducing atmosphere for calcination for 8 h, followed by cooling and slowly cooling to room temperature to obtain a cyan phosphate fluorescent material.

[0051] Example 3: This example provides a cyan phosphate fluorescent material, whose chemical structure is Ba 5- 5x Eu 5x P6O 20 (x=1.0%); Specifically, the preparation method of the material comprises the following steps:

[0052] (1) According to the molar ratio of each element in the above chemical structure, Ba:Eu:P=(5-5x):5x:6, x=1.0%, weigh the raw materials BaCO3, Eu2O3, and NH4H2PO4;

[0053] (2) Put the weighed raw materials into an agate mortar, add an appropriate amount of anhydrous ethanol as a dispersant and grind them thoroughly for 30 minutes until the anhydrous ethanol evaporates completely to obtain a uniform white powder;

[0054] (3) The ground white powder is placed in an alumina crucible, and the alumina crucible is placed in a muffle furnace at 750° C. in a reducing atmosphere for calcination for 8 h, followed by cooling and slowly cooling to room temperature to obtain a cyan phosphate fluorescent material.

[0055] Example 4: This example provides a cyan phosphate fluorescent material, whose chemical structure is Ba 5- 5x Eu 5x P6O 20 (x=1.25%); Specifically, the preparation method of the material comprises the following steps:

[0056] (1) According to the molar ratio of each element in the above chemical structure, Ba:Eu:P=(5-5x):5x:6, x=1.25%, weigh the raw materials BaCO3, Eu2O3, and NH4H2PO4;

[0057] (2) Put the weighed raw materials into an agate mortar, add an appropriate amount of anhydrous ethanol as a dispersant and grind them thoroughly for 30 minutes until the anhydrous ethanol evaporates completely to obtain a uniform white powder;

[0058] (3) The ground white powder is placed in an alumina crucible, and the alumina crucible is placed in a muffle furnace at 750° C. in a reducing atmosphere for calcination for 8 h, followed by cooling and slowly cooling to room temperature to obtain a cyan phosphate fluorescent material.

[0059] Example 5: This example provides a cyan phosphate fluorescent material, whose chemical structure is Ba 5- 5x Eu 5x P6O 20 (x=1.5%); Specifically, the preparation method of the material comprises the following steps:

[0060] (1) According to the molar ratio of each element in the above chemical structure, Ba:Eu:P=(5-5x):5x:6, x=1.5%, weigh the raw materials BaCO3, Eu2O3, and NH4H2PO4;

[0061] (2) Put the weighed raw materials into an agate mortar, add an appropriate amount of anhydrous ethanol as a dispersant and grind them thoroughly for 30 minutes until the anhydrous ethanol evaporates completely to obtain a uniform white powder;

[0062] (3) The ground white powder is placed in an alumina crucible, and the alumina crucible is placed in a muffle furnace at 750° C. in a reducing atmosphere for calcination for 8 h, followed by cooling and slowly cooling to room temperature to obtain a cyan phosphate fluorescent material.

[0063] Example 6: This example provides a cyan phosphate fluorescent material, whose chemical structure is Ba 5- 5x Eu 5x P6O 20 (x=1.2%); Specifically, the preparation method of the material comprises the following steps:

[0064] (1) According to the molar ratio of each element in the above chemical structure, Ba:Eu:P=(5-5x):5x:6, x=1.2%, weigh the raw materials BaO, Eu(OH)3, (NH4)2HPO4;

[0065] (2) Put the weighed raw materials into an agate mortar, add an appropriate amount of anhydrous ethanol as a dispersant and grind them thoroughly for 30 minutes until the anhydrous ethanol evaporates completely to obtain a uniform white powder;

[0066] (3) The ground white powder is placed in an alumina crucible, and the alumina crucible is placed in a muffle furnace at 700° C. in a reducing atmosphere for calcination for 10 h, followed by cooling and slowly cooling to room temperature to obtain a cyan phosphate fluorescent material.

[0067] Embodiment 7: This embodiment provides a cyan phosphate fluorescent material, whose chemical structure is Ba 5- 5x Eu 5x P6O 20 (x=1.0%); Specifically, the preparation method of the material comprises the following steps:

[0068] (1) According to the molar ratio of each element in the above chemical structure, Ba:Eu:P=(5-5x):5x:6, x=1.0%, weigh the raw materials BaCO3, Eu2(CO)3, and NH4H2PO4;

[0069] (2) Put the weighed raw materials into an agate mortar, add an appropriate amount of anhydrous ethanol as a dispersant and grind them thoroughly for 30 minutes until the anhydrous ethanol evaporates completely to obtain a uniform white powder;

[0070] (3) The ground white powder is placed in an alumina crucible, and the alumina crucible is placed in a muffle furnace at 800° C. in a reducing atmosphere for calcination for 6 hours, followed by cooling and slowly cooling to room temperature to obtain a cyan phosphate fluorescent material.

[0071] Comparative Example 1: This comparative example provides a fluorescent material, whose chemical structure is Ba5P6O 20 (x=0.5%); Specifically, the preparation method of the material comprises the following steps:

[0072] (1) Weigh the raw materials BaCO3 and NH4H2PO4 according to the molar ratio of each element in the above chemical structure formula Ba:P=5:6;

[0073] (2) Put the weighed raw materials into an agate mortar, add an appropriate amount of anhydrous ethanol as a dispersant and grind them thoroughly for 30 minutes until the anhydrous ethanol evaporates completely to obtain a uniform white powder;

[0074] (3) The ground white powder is placed in an alumina crucible, and the alumina crucible is placed in a muffle furnace at 750° C. in a reducing atmosphere for calcination for 8 h, followed by cooling and slowly cooling to room temperature to obtain a fluorescent material.

[0075] Performance test: The materials prepared in the above examples 1-5 and comparative example 1 were analyzed by powder X-ray diffraction (XRD) technology to obtain XRD patterns as shown in Figure 1 As shown; it can be seen that the material prepared in the embodiment of the present invention has good phase purity.

[0076] In addition, the emission and excitation spectra of the materials prepared in Examples 1-5 are as follows: Figure 2 , Figure 3 and Figure 4 As shown; it can be seen from the figure that the excitation spectrum of the material prepared in the embodiment of the present invention under 459nm monitoring shows a broadband excitation peak in the range of 250 to 400nm with 350nm as the center, indicating that it can be applied to WLEDs excited by ultraviolet chips. Under 350nm excitation, the material exhibits bright ultra-wideband cyan light emission, ranging from 400nm to near 750nm, with a half-peak width of 174nm, and the main peak wavelength of the emission is located near 459nm, which can well cover the cyan gap and is suitable for full-spectrum WLEDs.

[0077] The CIE chromaticity coordinate diagram of the material prepared in Example 3 is as follows Figure 5 As shown; the CIE coordinates of the material prepared in the embodiment of the present invention are calculated to be (0.2461, 0.297), which are close to the cyan CIE coordinates (0.1902, 0.2302), indicating that the material prepared in the embodiment of the present invention has the potential to fill the cyan gap in the spectrum;

[0078] The quantum efficiency of the material prepared in Example 3 is shown in FIG. Figure 6 As shown in the figure, it can be seen that the internal quantum efficiency of the material under 350nm excitation is 54.2%. The results show that the material prepared in the embodiment of the present invention has high internal quantum efficiency and has the potential to be applied to high-efficiency WLEDs.

[0079] The temperature-dependent emission spectrum of the material prepared in Example 3 is as follows Figure 7 As shown, the results show that when the temperature rises to 418K (145°C), its emission intensity still maintains 87.5% of the initial intensity, which has good thermal stability and is suitable for the WLEDs field.

[0080] Based on the above-mentioned ideal embodiments of the present invention, the relevant staff can make various changes and modifications without departing from the technical concept of the present invention through the above-mentioned description. The technical scope of the present invention is not limited to the contents of the specification.

Claims

1. A method for preparing a cyan phosphate fluorescent material, characterized in that: The chemical formula of the cyan phosphate fluorescent material is Ba 5-5x Eu 5x P6O 20 , wherein 0.5%≤x≤1.5%; the preparation method of the cyan phosphate fluorescent material comprises the following steps: Weigh the raw materials according to the molar ratio of each element in the chemical formula Ba:Eu:P=(5-5x):5x:6; wherein the raw materials include a Ba-containing compound, a Eu-containing compound and a P-containing compound; Add the weighed raw materials to the dispersant and grind them thoroughly until the dispersant evaporates to obtain a uniform white powder; In a reducing atmosphere, the ground white powder is calcined and then cooled to obtain the cyan phosphate fluorescent material; The Ba-containing compound is BaO and / or BaCO3; The Eu-containing compound is one or more of Eu2O3, Eu(OH)3, and Eu2(CO)3; The P-containing compound is one or more of NH4H2PO4 and (NH4)2HPO4.

2. The method for preparing the cyan phosphate fluorescent material according to claim 1, characterized in that: The dispersant is anhydrous ethanol.

3. The method for preparing the cyan phosphate fluorescent material according to claim 1, characterized in that: The calcination temperature is 700-800°C.

4. A cyan phosphate fluorescent material prepared by the preparation method according to any one of claims 1 to 3.

5. Use of the cyan phosphate fluorescent material as claimed in claim 4 in a light-emitting device.

6. The use according to claim 5, characterized in that: The light emitting device is a white light emitting diode lamp.

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