Rare earth fluorescent powder as well as preparation method and application thereof

Abstract

The invention provides rare earth fluorescent powder as well as a preparation method and application thereof, and relates to the technical field of rare earth luminescent materials. The chemical formula of the rare earth fluorescent powder provided by the invention is Na2Ti 3O7: xEu < 3 + >, the fluorescent powder has a P21 / m type space group structure. A proper amount of Eu < 3 + > ions are doped in Na2Ti 3O7, so that the prepared rare earth fluorescent powder has higher color rendering index and quantum yield, and further a WLED (White Light Emitting Diode) with high luminescence property is obtained; as Na2Ti 3O7 has good electrochemical performance and relatively high conductivity, the rare earth fluorescent powder provided by the invention can also be used in the fields of illumination, display, photocatalysis, energy storage and the like. And on the other hand, the preparation method provided by the invention is simple in process, mild in condition, convenient for large-scale production and wide in development and application space.

Description

Technical Field

[0001] The invention relates to the technical field of rare earth luminescent materials, and in particular to a rare earth phosphor and a preparation method and application thereof. Background Art

[0002] Luminescent materials, or phosphors, refer to materials that can enter an excited state due to the effects of light, rays, high-energy particles, and electric fields, and convert the excited state energy into visible light, ultraviolet light, or near-infrared light. Luminescent materials are generally composed of a matrix and a luminescent center. Among them, the matrix is ​​the carrier of the luminescent center, providing different crystal field environments for the luminescent center ions, thereby affecting the luminescent properties of the luminescent material; the luminescent center is a specific center that can emit photons after being excited. The luminescent center is generally composed of a small amount of doped ions, namely activators. Common luminescent centers include rare earth ions, transition metal ions, and defect luminescent centers.

[0003] Rare earth ions are the most widely used and most effective activator ions, with advantages such as high emission intensity, high quantum efficiency and low susceptibility to environmental influences.

[0004] The methods for preparing luminescent materials mainly include solution method, coprecipitation method, high temperature solid phase method, sol-gel method, etc. Among them, high temperature solid phase method is a common method for preparing metal oxide luminescent materials. However, in actual use, it is found that most phosphors have problems such as insufficient color purity and color reproduction ability, and high energy consumption. Therefore, it is very necessary to develop a phosphor with high color purity, high color reproduction ability, high quantum efficiency and low energy consumption. Summary of the invention

[0005] The purpose of the present invention is to provide a rare earth phosphor and a preparation method and application thereof, so as to solve the technical problems existing in the prior art that the phosphor has low quantum efficiency, high energy consumption, and insufficient color purity and restoration ability.

[0006] In order to solve the above technical problems, the present invention provides a rare earth phosphor, the chemical formula of which is Na2Ti3O7:xEu 3+ ; The phosphor has a P21 / m type space group structure.

[0007] Furthermore, in the chemical formula of the phosphor, the range of x is 0.025≤x≤0.2.

[0008] The present invention also provides a method for preparing the rare earth phosphor, the specific steps of which are as follows:

[0009] Step 1, according to the molar ratio of sodium element to titanium element being 2.2:3, weighing a compound containing sodium ions and a compound containing titanium ions respectively, and then weighing a compound containing europium ions at a molar ratio of the mixture to europium element being 1:x, and mixing to obtain a first mixture; the range of x is 0.025≤x≤0.2

[0010] Step 2, adding the first mixture into a mortar, and continuously grinding under dry conditions to obtain a second mixture with a moderate particle size;

[0011] Step 3, placing the second mixture in a heating device for calcination, gradually heating it to the reaction temperature, and after the reaction is complete, naturally cooling and keeping it dry, and grinding it to obtain the rare earth phosphor.

[0012] Furthermore, the compound containing sodium ions in step 1 is sodium carbonate and / or sodium bicarbonate;

[0013] The compound containing titanium ions is titanium dioxide and / or titanium tetraoxide;

[0014] The compound containing europium ions is europium oxide.

[0015] Furthermore, the grinding time is 2-3h.

[0016] Furthermore, the calcination temperature in step 3 is 1200K-1300K, preferably 1223K.

[0017] Furthermore, the heating rate in step 3 is 6-8 K / min, preferably 7 K / min.

[0018] Furthermore, the reaction time in step 3 is 10-12 hours.

[0019] On the other hand, the present invention also provides an application of the above rare earth phosphor, wherein the application field is selected from lighting, display, photocatalysis, and energy storage.

[0020] Furthermore, the application is a light emitting device;

[0021] The light-emitting device comprises a semiconductor light-emitting chip and a fluorescent material composition;

[0022] The fluorescent material composition contains the rare earth fluorescent powder or the rare earth fluorescent powder obtained according to the above preparation method.

[0023] By adopting the above technical solution, the present invention has the following beneficial effects:

[0024] The present invention provides a rare earth phosphor, which is prepared by doping an appropriate amount of Eu into Na2Ti3O7. 3+ions, so that the prepared rare earth phosphor has a higher color rendering index and quantum yield, thereby obtaining a WLED with high luminous performance; since Na2Ti3O7 has good electrochemical properties and high electrical conductivity, the rare earth phosphor provided by the present invention can be used in the fields of lighting, display, photocatalysis and energy storage. On the other hand, the preparation method provided by the present invention has a simple process, mild conditions, is easy to mass produce, and has a broad development and application space. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0026] Figure 1 A scanning electron microscope (SEM) image of the rare earth phosphor provided by the present invention;

[0027] FIG2( a) is a transmission electron microscope (TEM) image of the rare earth phosphor obtained in Example 2;

[0028] FIG2( b ) is a schematic diagram showing the measurement of the lattice spacing of the rare earth phosphor obtained in Example 2;

[0029] FIG2(c) is a transmission electron microscope diffraction pattern of the rare earth phosphor obtained in Example 2;

[0030] FIG3( a ) is a schematic diagram of the assembly structure of the rare earth phosphor obtained in Example 4 in a white light device;

[0031] FIG3( b ) is a diagram showing the effect of the rare earth phosphor obtained in Example 4 in the packaging test of a white light device;

[0032] Figure 4 The CIE chromaticity diagram obtained in Example 4;

[0033] Figure 5 The rare earth phosphor Na2Ti3O7:xEu obtained in Example 1-4 3+ XRD pattern of

[0034] Figure 6 The rare earth phosphor Na2Ti3O7:xEu obtained in Example 5 and Comparative Examples 1-2 3+ XRD pattern of

[0035] Figure 7 The excitation spectra of each group of rare earth phosphors measured in Experimental Example 1;

[0036] Figure 8 The emission spectra of each group of rare earth phosphors measured in Experimental Example 1 are shown. DETAILED DESCRIPTION

[0037] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. 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.

[0038] The present invention is further explained below in conjunction with specific implementation modes.

[0039] Step 1, weighing a compound containing sodium ions and a compound containing titanium ions respectively according to a molar ratio of sodium element to titanium element of 2.2:3, and then weighing a compound containing europium ions according to a molar ratio of the mixture to europium element of 1:x, and mixing to obtain a first mixture;

[0040] The range of x is 0.025≤x≤0.2;

[0041] Step 2, adding the first mixture into a mortar, and grinding continuously for 2-3 hours under dry conditions to obtain a second mixture with a moderate particle size;

[0042] Step 3, placing the second mixture in a heating device and raising the temperature to 1200K-1300K at a rate of 6-8K / min for calcination for 10-12h. After the reaction is complete, naturally cool and keep dry, and grind to obtain the rare earth phosphor.

[0043] Example 1

[0044] like Figure 1 As shown, rare earth phosphor is obtained according to the preparation method provided by the present invention.

[0045] Step 1, weighing 0.1166 g of sodium carbonate, 0.2397 g of titanium dioxide, and 0.018 g of europium oxide respectively, and mixing them evenly to obtain a first mixture;

[0046] Step 2, adding the first mixture into a mortar and grinding for 2.5 hours to obtain a second mixture with a moderate particle size;

[0047] Step 3, placing the second mixture in a heating device and heating it at a rate of 7K / min, maintaining the temperature for 11 hours when the temperature reaches 1223K, cooling it naturally to obtain a block product, and grinding the block product to obtain the rare earth phosphor Na2Ti3O7:xEu 3+ , where x = 0.025. Figure 1As shown, under a scanning electron microscope, it can be clearly seen that the rare earth phosphor particles obtained in this embodiment are evenly distributed, and the grains are irregular rod-shaped structures.

[0048] Example 2

[0049] like Figure 2(a)-Figure 2(c) As shown, this example verifies the microscopic lattice structure of the obtained rare earth phosphor under a transmission electron microscope.

[0050] Step 1, weighing 0.1166 g of sodium carbonate, 0.2397 g of titanium dioxide, and 0.0721 g of europium oxide respectively, and mixing them evenly to obtain a first mixture;

[0051] Step 2, adding the first mixture into a mortar and grinding for 3 hours to obtain a second mixture with a moderate particle size;

[0052] Step 3, placing the second mixture in a heating device and heating it at a rate of 6K / min, maintaining the temperature for 10 hours when the temperature reaches 1223K, cooling it naturally to obtain a block product, and grinding the block product to obtain the rare earth phosphor Na2Ti3O7:xEu 3+ , where x=0.1.

[0053] It can be seen from the transmission electron microscope that the lattice stripes of the rare earth phosphor (x=0.1) prepared in this embodiment are clear, as shown in FIG2(a); and the lattice spacing is 0.19003 nm as shown in FIG2(b) measured by microscope. The position of the crystal plane marked in the transmission electron microscope diffraction pattern is shown in FIG2(c), indicating that the unit cell structure of the rare earth phosphor prepared by the method provided by the present invention is consistent with the unit cell structure of P21 / m, further proving that the prepared substance is Na2Ti3O7.

[0054] Example 3

[0055] This example verifies the effect of different europium oxide addition amounts on the structure of the prepared rare earth phosphor

[0056] Step 1, weighing 0.1166 g of sodium carbonate, 0.2397 g of titanium dioxide, and 0.036 g of europium oxide respectively, and mixing them evenly to obtain a first mixture;

[0057] Step 2, adding the first mixture into a mortar and grinding for 2 hours to obtain a second mixture with a moderate particle size;

[0058] Step 3, placing the second mixture in a heating device and heating it at a rate of 6K / min, maintaining the temperature for 10 hours when the temperature reaches 1223K, cooling it naturally to obtain a block product, and grinding the block product to obtain the rare earth phosphor, Na2Ti3O7:xEu 3+, where x=0.05.

[0059] Example 4

[0060] like Figure 3(a)-Figure 4 As shown, this example verifies the color rendering effect and brightness improvement effect of the rare earth phosphor obtained by the preparation method provided by the present invention.

[0061] Step 1, weighing 0.1166 g of sodium carbonate, 0.2397 g of titanium dioxide, and 0.1442 g of europium oxide respectively, and mixing them evenly to obtain a first mixture;

[0062] Step 2, adding the first mixture into a mortar and grinding for 2.5 hours to obtain a second mixture with a moderate particle size;

[0063] Step 3, placing the second mixture in a heating device and heating it at a rate of 6K / min, maintaining the temperature for 10 hours when the temperature reaches 1223K, cooling it naturally to obtain a block product, and grinding the block product to obtain the rare earth phosphor, Na2Ti3O7:xEu 3+ , where x=0.2.

[0064] like Figure 3(a)-Figure 3(b) As shown, the phosphor obtained in this embodiment shows good color rendering effect in the packaging test of white light devices, and emits bright white light under power-on conditions. Figure 4 As shown, the position displayed by the obtained CIE chromaticity diagram coordinates (x=0.3635y=0.3877) is also exactly at the position of white light, indicating that the rare earth phosphor obtained by the present invention can effectively enhance color mixing, improve the overall brightness and color rendering of the light source, and form a more uniform and bright white light effect with high color purity.

[0065] Example 5

[0066] like Figure 5-Figure 6 As shown, this example verifies the influence of different calcination temperatures on the purity of the prepared rare earth phosphor.

[0067] Step 1, weighing 0.1166 g of sodium carbonate, 0.2397 g of titanium dioxide, and 0.018 g of europium oxide respectively, and mixing them evenly to obtain a first mixture;

[0068] Step 2, adding the first mixture into a mortar and grinding for 2 hours to obtain a second mixture with a moderate particle size; repeating steps 1 and 2 to obtain two groups of second mixtures;

[0069] Step 3, placing the two groups of second mixtures in a heating device and heating them at a rate of 7K / min, maintaining the reaction at temperatures of 1323K and 1173K for 11 hours, cooling naturally to obtain block products, and grinding the block products to obtain two groups of rare earth phosphors Na2Ti3O7:xEu 3+ , where X = 0.025.

[0070] like Figure 5 As shown, the rare earth phosphors obtained in Examples 1-4, Na2Ti3O7:xEu 3+ It can be seen from the X-ray diffraction patterns of X=0.025, 0.05, 0.1, and 0.2 that when the calcination temperature is 1223K, the peak positions of the four groups of rare earth phosphors with different europium ion contents are basically consistent with the standard card of Na2Ti3O7 in the crystal library, namely PDF#72-0148, which proves that the rare earth phosphors prepared by the method provided by the present invention have higher purity.

[0071] X-ray diffraction analysis of the two groups of rare earth phosphors obtained in this embodiment shows that Figure 6 As shown, under the premise of adding the same mass of europium ions, when the calcination reaction temperature is lower than 1200K or higher than 1300K, the diffraction peak in the XRD diagram of the obtained rare earth phosphor is significantly different from the peak position of the standard card. It can be proved that when the calcination temperature is lower than 1200K or higher than 1300K, the purity of the obtained rare earth phosphor is significantly reduced. This is because when the calcination temperature is lower than 1200K, part of the raw materials are not fully reacted and are likely to remain in the obtained rare earth phosphor; when the calcination temperature is higher than 1300K, the rare earth phosphor that has been reacted will be over-burned, generating additional impurities such as carbon, thereby affecting the purity of the reaction product. Therefore, the temperature for the calcination reaction in the preparation method provided by the present invention is recommended to be 1200K-1300K, preferably 1223K.

[0072] Comparative Example 1

[0073] like Figure 6 As shown, the influence of different added mass of europium ions on the purity of the prepared rare earth phosphor was verified.

[0074] Step 1, weighing 0.1166 g of sodium carbonate, 0.2397 g of titanium dioxide, and 0.1803 g of europium oxide respectively, and mixing them evenly to obtain a first mixture;

[0075] Step 2, adding the first mixture into a mortar and grinding for 2 hours to obtain a second mixture with a moderate particle size;

[0076] Step 3, placing the second mixture in a heating device and heating it at a rate of 6K / min, maintaining the temperature for 10 hours when the temperature reaches 1223K, cooling it naturally to obtain a block product, and grinding the block product to obtain the rare earth phosphor, Na2Ti3O7:xEu 3+ , where x=0.25.

[0077] like Figure 6 As shown in the figure, when x=0.25, although the calcination temperature is between 1200-1300K, the spectrum of the obtained rare earth phosphor still shows obvious impurity peaks compared with the standard card of Na2Ti3O7, proving that when the doping concentration exceeds 0.2, the purity of the obtained rare earth phosphor will be significantly reduced. Therefore, in the preparation method provided by the present invention, the doping concentration of europium ions in Na2Ti3O7 is preferably 0.025≤x≤0.2.

[0078] Comparative Example 2

[0079] Step 1, weighing 0.1166 g of sodium carbonate, 0.2397 g of titanium dioxide, and 0.01443 g of europium oxide, respectively, mixing them evenly, and obtaining a first mixture;

[0080] Step 2, adding the first mixture into a mortar and grinding for 2.5 hours to obtain a second mixture with a moderate particle size;

[0081] Step 3, placing the second mixture in a heating device and heating it at a rate of 6K / min, maintaining the temperature for 10 hours when the temperature reaches 1223K, cooling it naturally to obtain a block product, and grinding the block product to obtain the rare earth phosphor, Na2Ti3O7:xEu 3+ , where X = 0.0125.

[0082] like Figure 6 As shown, the rare earth phosphor obtained in Comparative Example 2, Na2Ti3O7:xEu 3+ , where X = 0.0125, it can be clearly seen that compared with the standard card of Na2Ti3O7 in the crystal library, PDF#72-0148, there are fewer impurity peaks and the purity is relatively high. Figure 7-8 As shown, the lower doping ratio of europium ions leads to a decrease in the overall luminescence performance of the phosphor.

[0083] Experimental Example 1

[0084] like Figure 7-Figure 8 As shown, the luminescence performance of the rare earth phosphors obtained in Examples 1-4 and Comparative Examples 1-2 was verified.

[0085] The excitation and emission spectra were tested using the Edinburgh FL S1000 fluorescence spectrometer from the UK. At an excitation wavelength of 393 nm, the excitation spectrum was tested in the range of 200-500 nm; the emission spectrum was tested in the range of 550-750 nm. Figure 7-Figure 8 As shown, the rare earth phosphors obtained in Examples 1-4 all exhibit narrow-band emission in the test range of 550-750nm. When the doping concentration x=0.025, the luminous intensity is the weakest, because the excitation efficiency is low due to the low doping concentration; when the doping concentration is x=0.05, the luminous effect is optimal, which can effectively enhance energy transfer and luminous efficiency; when the doping concentration x=0.1, the luminous intensity is reduced, mainly because when the doping concentration is too high, energy aggregation or self-absorption occurs, which inhibits the emission of light; when the doping concentration is further increased to x=0.2, the luminous intensity decreases more significantly, because excessive doping will enhance the interaction of fluorescent centers, thereby reducing the overall luminous efficiency. Therefore, in the preparation method of the rare earth phosphor provided by the present invention, the doping concentration is preferably 0.025≤x≤0.2.

[0086] In summary, the rare earth phosphor provided by the present invention creatively doped Eu into Na2Ti3O7. 3+ ions, so that the prepared rare earth phosphor has a higher color rendering index and quantum yield, thereby obtaining a WLED with high luminous performance. The preparation method provided by the present invention controls the key parameters of the addition amount of europium oxide, the calcination temperature, and the reaction time to prepare a rare earth phosphor with high luminous intensity, which can significantly improve the overall brightness and color rendering performance of the light source. Since Na2Ti3O7 has good electrochemical properties and high electrical conductivity, the rare earth phosphor provided by the present invention can be used in the fields of lighting, display, photocatalysis, and energy storage.

[0087] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A rare earth phosphor, characterized in that: The chemical formula of the phosphor is Na2Ti3O7:xEu 3+ ; The phosphor has a P21 / m type space group structure.

2. The rare earth phosphor according to claim 1, characterized in that: In the chemical formula of the phosphor, the range of x is 0.025≤x≤0.

2.

3. A method for preparing the rare earth phosphor according to claim 1, characterized in that: The specific steps are as follows: Step 1, weighing a compound containing sodium ions and a compound containing titanium ions respectively according to a molar ratio of sodium element to titanium element of 2.2:3, and then weighing a compound containing europium ions according to a molar ratio of the mixture to europium element of 1:x, and mixing to obtain a first mixture; Step 2, adding the first mixture into a mortar and continuously grinding under dry conditions; A second mixture with a moderate particle size is obtained; Step 3, placing the second mixture in a heating device for calcination, gradually heating it to the reaction temperature, and after the reaction is complete, naturally cooling and keeping it dry, and grinding it to obtain the rare earth phosphor.

4. The preparation method according to claim 3, characterized in that: The sodium ion-containing compound in step 1 is sodium carbonate and / or sodium bicarbonate; The titanium ion compound is titanium dioxide and / or titanium tetraoxide; The compound containing europium ions is europium oxide; The range of the molar ratio x of the europium element added in step 1 is 0.025≤x≤0.

2.

5. The preparation method according to claim 3, characterized in that: The grinding time is 2-3h.

6. The preparation method according to claim 3, characterized in that: The calcination temperature in step 3 is 1200K-1300K.

7. The preparation method according to claim 3, characterized in that: The heating rate in step 3 is 6-8K / min.

8. The preparation method according to claim 3, characterized in that: The reaction time in step 3 is 10-12 hours.

9. Use of the rare earth phosphor according to any one of claims 1 to 2 or the rare earth phosphor obtained by the preparation method according to any one of claims 3 to 8, characterized in that: The application field is selected from lighting, display, photocatalysis, and energy storage.

10. The use according to claim 9, characterized in that: The application is a light emitting device; The light-emitting device comprises a semiconductor light-emitting chip and a fluorescent material composition; The fluorescent material composition contains the rare earth fluorescent powder according to any one of claims 1 to 2 or the rare earth fluorescent powder obtained by the preparation method according to any one of claims 3 to 8.

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