Blue light fluorescent powder with self-activation effect and preparation method thereof

Abstract

The application belongs to the technical field of fluorescent material synthesis, and particularly relates to a blue fluorescent powder with self-activation effect and a preparation method thereof, the chemical formula of the blue fluorescent powder is Li2Mg2W2O9 or Li2Zn2W2O9; the preparation comprises the following steps: 1) according to the chemical proportion of the fluorescent powder, magnesium / zinc source, lithium source and tungsten source are weighed and uniformly ground; 2) the uniformly ground mixed powder is placed into an alumina crucible, sintering is carried out, and the product is fully reacted after heat preservation for a period of time; 3) the product is uniformly ground again after cooling, and the blue fluorescent powder with self-activation effect is obtained. The application utilizes the special lattice structure of the substrate, and obtains the blue fluorescent powder with self-activation effect under an air atmosphere; the generated product has high purity, simple synthesis conditions, low cost and is easy to be prepared on a large scale; the prepared fluorescent powder has a high internal quantum efficiency of 68.7%, high luminous intensity and unique blue light emission characteristics.

Description

Technical Field

[0001] This invention belongs to the field of fluorescent material synthesis technology, specifically relating to a blue phosphor with self-activation effect and its preparation method. Background Technology

[0002] Due to its significant advantages such as high luminous efficiency, long lifespan, and environmental friendliness, LEDs have broken through various limitations of traditional light sources and are widely used in various fields such as indoor and outdoor lighting, plant lighting, and backlight displays. Currently, commercially available WLED phosphors mainly include YAG:Ce. 3+ CaAlSiN3:Eu 2+ and Sr2Si5N8:Eu 2+ Rare earth materials are needed for various processes, including phosphors. However, due to the high costs associated with the separation, refining, and purification of rare earth materials, they are mostly expensive, and rare earth reserves are limited, which is detrimental to sustainable development. Therefore, researchers have conducted extensive research on phosphors without rare earth doping.

[0003] In recent years, the morphology, synthesis, size, and optical and electrical properties of tungstates have been extensively studied. Tungstates are important self-activated luminescent materials, and their luminescence modes mainly include charge-transfer luminescence, defect luminescence, and exciton luminescence. With activation ion doping, energy transfer luminescence also occurs. Charge-transfer transitions are attributed to electron transitions between ligand orbital energy levels and the metal of the complex group, i.e., electron transitions between oxygen and transition metals in anionic groups. Common closed-shell transition metal compounds mainly include the following categories: Group IVB includes titanates ([TiO4)). 4- and [TiO6] 8- ) and zirconate ([ZrO6]) 8- Group VB contains vanadates ([VO4]). 3- ), niobate ([NbO4]) 3- and [NbO6] 7- ), Tantalate ([TaO6]) 7- Group VIB contains chromates ([CrO4]). 2- ), molybdate ([MoO4]) 2- and [MoO6] 6- ), tungstate ([WO4]) 2- and [WO6] 6- Group VIIB contains manganate salts ([MnO4]). 2- Technetium salt ([TcO4]) 2- Group VIII contains ruthenium salts ([RuO4]). 2-In particular, tungstates, molybdates, vanadates, etc., have high photoluminescence quantum yields and excitation and emission characteristics that depend on the external environment and preparation method, making these self-activated materials widely studied.

[0004] The structural chemistry of tungstate materials has been a subject of widespread interest. Three main WO4 anionic groups are present in their crystals: [WO4] 2- [WO5] 4 -and [WO6] 6 These groups are connected in various ways, such as sharing vertices, edges, and faces. These factors collectively contribute to the diversity of tungstate structures and properties. Tungstates have a wide range of applications, primarily as Raman laser crystals, scintillation crystals for determining the fundamental properties of high-energy particles and for medical imaging, component materials for lithium batteries and fuel cells, photocatalysts, and fluxes for the growth of functional single crystals, among others.

[0005] In the current technology, there is a lack of phosphors with high internal quantum efficiency that can emit blue light at an excitation wavelength of 266nm. Summary of the Invention

[0006] The purpose of this invention is to provide a blue phosphor with a self-activating effect and its preparation method. This method uses a traditional high-temperature solid-state method to prepare a phosphor with high internal quantum efficiency that emits blue light at an excitation wavelength of 266 nm under an air atmosphere.

[0007] To achieve the above-mentioned technical objectives and effects, the present invention is implemented through the following technical solution:

[0008] A blue phosphor with a self-activating effect, the chemical formula of which is Li2Mg2W2O9 or Li2Zn2W2O9.

[0009] Furthermore, the preparation of Li2Mg2W2O9 includes the following steps:

[0010] 1) Weigh the magnesium source, lithium source, and tungsten source according to the chemical ratio of the phosphor, and grind them evenly;

[0011] 2) Place the evenly ground mixed powder into an alumina crucible, sinter it, and keep it at the temperature for a period of time to allow it to react fully;

[0012] 3) After cooling, the product is ground again to obtain a blue phosphor with a self-activation effect.

[0013] Furthermore, in step 1), the magnesium source is basic magnesium carbonate, the lithium source is lithium carbonate, and the tungsten source is tungsten oxide. The purity of basic magnesium carbonate, lithium carbonate, and tungsten oxide is ≥99.5%.

[0014] Furthermore, in step 1), the magnesium source is magnesium nitrate, the lithium source is lithium nitrate, and the tungsten source is ammonium paratungstate.

[0015] Furthermore, the preparation of Li2Zn2W2O9 includes the following steps:

[0016] 1) Weigh the zinc source, lithium source, and tungsten source according to the chemical ratio of the phosphor, and grind them evenly;

[0017] 2) Place the evenly ground mixed powder into an alumina crucible, sinter it, and keep it at the temperature for a period of time to allow it to react fully;

[0018] 3) After cooling, the product is ground again to obtain a blue phosphor with a self-activation effect.

[0019] Furthermore, in step 1), the zinc source is zinc oxide, the lithium source is lithium carbonate, and the tungsten source is tungsten oxide.

[0020] Furthermore, in step 2), the sintering reaction temperature is 750-950℃, and the reaction holding time is 3-8h.

[0021] Furthermore, the reaction apparatus for step 3) sintering is a muffle furnace or a tube furnace.

[0022] The beneficial effects of this invention are:

[0023] 1. This invention utilizes the special lattice structure of the matrix to obtain a blue phosphor with a self-activation effect in an air atmosphere.

[0024] 2. The method of the present invention produces products with high purity, simple synthesis conditions, low cost, and is easy to prepare on a large scale.

[0025] 3. The phosphor prepared by this invention has an internal quantum efficiency of up to 68.7%, high luminescence intensity, and unique blue light emission characteristics.

[0026] Of course, any product implementing this invention does not necessarily need to achieve all of the above advantages at the same time. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 The XRD pattern of the phosphor prepared in Example 1;

[0029] Figure 2 The emission spectrum of the phosphor prepared in Example 1;

[0030] Figure 3 The excitation spectrum of the phosphor prepared in Example 1;

[0031] Figure 4 The internal quantum efficiency spectrum of the phosphor prepared in Example 1;

[0032] Figure 5 The XRD pattern of the phosphor prepared in Example 2;

[0033] Figure 6 The emission spectrum of the phosphor prepared in Example 2;

[0034] Figure 7 The XRD pattern of the phosphor prepared in Example 3;

[0035] Figure 8 The emission spectrum of the phosphor prepared in Example 3 is shown. Detailed Implementation

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] Example 1

[0038] Weigh out 0.00112 mol of basic magnesium carbonate (MgCO3)4·Mg(OH)2·5H2O with a purity of 99.8%, 0.0028 mol of Li2CO3 with a purity of 99.9%, and 0.0056 mol of WO3 with a purity of 99.99%.

[0039] The above raw materials were thoroughly ground in an agate mortar and pestle, then placed in a corundum crucible and sintered in a muffle furnace. The temperature was increased from room temperature to 750°C at a rate of 10°C / min, and held at 750°C for 3 hours. After the experimental system cooled naturally, the crucible was removed. After grinding again until homogeneous, the target product Li2Mg2W2O9 was obtained, which appeared as a white powder.

[0040] Figure 1 The image shows the XRD pattern of the final target product powder obtained in Example 1. The data indicates that the prepared sample has good phase formation and high crystallinity.

[0041] Figure 2The figure shows the emission spectrum of the final target product powder obtained in Example 1. As can be seen from the figure, the sample obtained an emission peak with a center wavelength of 456 nm under deep ultraviolet light excitation at 266 nm, which is an effective and bright blue light emission.

[0042] Figure 3 The excitation spectrum of the final target product powder obtained in Example 1 shows that, based on the emission intensity, the blue light excitation efficiency at 256 nm is the highest in the excitation spectrum at a monitoring wavelength of 450 nm.

[0043] Figure 4 This is the internal quantum efficiency spectrum of the final target product powder obtained in Example 1, with the phosphor having an internal quantum efficiency of 68.7%.

[0044] Example 2

[0045] A sol-gel method for preparing a blue phosphor with a self-activating effect, wherein the phosphor also has the chemical formula Li2Mg2W2O9.

[0046] Weigh out 4 ml of 1 mol / L lithium nitrate (LiNO3), 4 ml of 1 mol / L magnesium nitrate (Mg(NO3)2), and 3.36 g of citric acid (C6H8O7H). 20 1.04g of H 40 N 10 O 41 W 12 ·5H2O.

[0047] The above raw materials were first stirred in a constant-temperature magnetic stirrer for 0.5 h, and then placed in an oven at 80 °C for 18 h. Afterwards, the raw materials were kept at 400 °C for 30 min, then thoroughly ground in an agate mortar with a pestle. The resulting powder was then placed in a corundum crucible and sintered in a muffle furnace. The temperature was increased from room temperature to 750 °C at a rate of 10 °C / min, and held at 750 °C for 3 h. After the experimental system cooled naturally, the crucible was removed. After grinding again until homogeneous, the target product Li₂Mg₂W₂O₉ was obtained, which appeared as a white powder.

[0048] Figure 5 The image shows the XRD pattern of the final target product powder obtained in Example 2. The data indicates that the prepared sample has good phase formation and high crystallinity.

[0049] Figure 6 The emission spectrum is the final target product powder obtained in Example 2, and the emission spectrum is similar to that of Example 1.

[0050] Example 3

[0051] A method for preparing a manganese-doped blue phosphor with a self-activating effect, wherein the phosphor has the chemical formula Li₂Zn₂W₂O₉: 0.4 mol% Mn 4+ The preparation steps are basically the same as in Example 1, except that the reaction raw material (MgCO3)4·Mg(OH)2·5H2O is changed to ZnO with a purity of 99.9%, and the molar ratio remains unchanged. The content of reactant WO3 is reduced by 0.4%, and 0.4% of MnCO3 is added.

[0052] Figure 7 The image shows the XRD pattern of the final target product powder obtained in Example 3. The data indicates that the prepared sample has good phase formation and high crystallinity.

[0053] Figure 8 The emission spectrum is the final target product powder obtained in Example 3, and the emission spectrum is similar to that of Example 1.

[0054] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. The application of a blue phosphor with a self-activating effect as a fluorescent material, characterized in that: The chemical formula of this blue phosphor is Li₂Mg₂W₂O₉. The preparation of Li₂Mg₂W₂O₉ includes the following steps: 1) Weigh the magnesium source, lithium source, and tungsten source according to the chemical ratio of the phosphor, and grind them evenly; 2) Place the evenly ground mixed powder into an alumina crucible, sinter it, and keep it at the temperature for a period of time to allow it to react fully; 3) After cooling, the product is ground again to obtain a blue phosphor with self-activation effect. The blue phosphor can obtain an emission peak with a center wavelength of 456nm under deep ultraviolet light excitation at 266nm. The internal quantum efficiency of the blue phosphor is 68.7%.

2. The application according to claim 1, characterized in that: In step 1), the magnesium source is basic magnesium carbonate, the lithium source is lithium carbonate, and the tungsten source is tungsten oxide.

3. The application according to claim 1, characterized in that: In step 1), the magnesium source is magnesium nitrate, the lithium source is lithium nitrate, and the tungsten source is ammonium paratungstate.

4. The application of a blue phosphor with a self-activating effect as a fluorescent material, characterized in that: The chemical formula of this blue phosphor is Li₂Zn₂W₂O₉. The preparation of Li₂Zn₂W₂O₉ includes the following steps: 1) Weigh the zinc source, lithium source, and tungsten source according to the chemical ratio of the phosphor, and grind them evenly; 2) Place the evenly ground mixed powder into an alumina crucible, sinter it, and keep it at the temperature for a period of time to allow it to react fully; 3) After cooling, the product is ground again to obtain a blue phosphor with a self-activation effect.

5. The application according to claim 4, characterized in that, In step 1), the zinc source is zinc oxide, the lithium source is lithium carbonate, and the tungsten source is tungsten oxide.

6. The application according to claim 1 or 4, characterized in that: In step 2), the sintering reaction temperature is 750-950℃, and the reaction holding time is 3-8 h.

7. The application according to claim 1 or 4, characterized in that: Step 3) The sintering reaction apparatus is a muffle furnace or a tube furnace.

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