Orange red fluorescent material as well as preparation method and application thereof

Abstract

The invention provides an orange red fluorescent material as well as a preparation method and application thereof, and belongs to the technical field of fluorescent materials. According to the orange red fluorescent material provided by the invention, KSrBP2O8 is taken as a matrix, Sm < 3 + > and M are taken as active ions, and M is Eu < 3 + > or Si < 4 + >. The light color and the luminous intensity of the KSrBP2O8: Sm < 3 + >, Eu < 3 + > / Si < 4 + > orange red fluorescent powder provided by the invention can be regulated and controlled by changing the concentration of rare earth ions, and compared with single-doped Sm < 3 + > fluorescent powder, the double-doped KSrBP2O8: Sm < 3 + >, Eu < 3 + > / Si < 4 + > orange red fluorescent powder has higher luminous intensity and higher red purity.

Description

Technical Field

[0001] The present invention relates to the technical field of fluorescent materials, and particularly relates to an orange-red fluorescent material, a preparation method thereof, and an application thereof. Background Art

[0002] Boron phosphates have rich anion and cation lattice sites, and they contain both phosphate groups and borate groups. Among boron phosphate compounds, there are some compounds with planar triangular coordination of (BO3) groups, but relatively speaking, such compounds are rare. The coordination number of most boron compounds is four, and there are also some boron compounds with the characteristics of both three-coordination and four-coordination. These complexes are like tetrahedrons in the silicate system, and they are connected by sharing vertices to form various shapes. They will also complex with transition metals or main group elements to form polyhedron connections. Generally, these anion groups in boron phosphates will be connected together by common vertices to form ring-shaped, chain-shaped, layered, framework-shaped, island-shaped or cluster-shaped negatively charged ion structures, and then these structures will be connected with some metal-oxygen polyhedrons to form a complex three-dimensional network structure. KSrBP2O8 has a three-dimensional structure, in which borate and phosphate anion groups have strong absorption in the near-ultraviolet / ultraviolet region. At the same time, the metal-oxygen copolymer unit or polyhedron (M x O y ) can provide a variety of cation crystal field coordination environments for rare earth ion doping substitution. These anion and cation groups can be connected to each other, resulting in a rich and diverse coordination environment of the polyhedron (M x O y ) formed by the coordination of metal atoms and oxygen atoms, which is conducive to providing a variety of coordination field environments for the doping of rare earth ions. Since boron phosphates can provide rich doping lattice sites for activator ions, they have become important matrix materials for spectroscopically tunable phosphors.

[0003] Samarium (Sm) is one of the light rare earth elements in the lanthanide series. Sm easily loses three electrons in compounds and transforms into relatively stable trivalent Sm 3+ ions. Since the 4f electrons of Sm 3+ are surrounded by the 5s 2 5p 6 shells, the spectral properties of Sm 3+ are not easily affected by the external lattice. The spectrum of Sm 3+ includes absorption transitions, non-radiative transitions, thermally coupled transitions, and radiative transitions. Sm 3+ is easily excited by near-ultraviolet light and emits orange-red light at 600 nm. However, existing rare earth single-doped borate and phosphate phosphors have problems such as insufficient crystal lattice sites, poor light color tunability, low luminous intensity, low color purity, high preparation temperature, and long reaction time. Summary of the Invention

[0004] In view of the above problems, the object of the present invention is to provide a dual-doped KSrBP2O8:Sm 3+ ,Eu 3 + / Si 4+ orange-red phosphor.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] One of the technical solutions of the present invention is an orange-red fluorescent material, with KSrBP2O8 as the matrix and Sm 3+ and M as the activating ions, where M is Eu 3+ or Si 4+ ;

[0007] When M is Eu 3+ , the chemical formula of the orange-red fluorescent material is KSr 1-x-y BP2O8:xSm 3+ ,yEu 3+ ; where 0.001 ≤ x ≤ 0.016, 0.002 ≤ y ≤ 0.010;

[0008] When M is Si 4+ , the chemical formula of the orange-red fluorescent material is KSr 1-x B 1-z P2O8:xSm 3+ ,zSi 4+ ; where 0.001 ≤ x ≤ 0.016, 0.01 ≤ z ≤ 0.05.

[0009] Another technical solution of the present invention is a preparation method of the above orange-red fluorescent material, including the following steps:

[0010] Step 1. Weigh the raw materials according to the chemical formula, then grind and dry them to obtain powder 1;

[0011] Step 2. Pre-calcine the powder 1 in an air atmosphere, then grind it to obtain powder 2;

[0012] Step 3. Calcinate the powder 2 in an air atmosphere, then grind it to obtain the orange-red fluorescent material.

[0013] Another technical solution of the present invention is the application of the above orange-red fluorescent material in LED luminescent materials.

[0014] The present invention discloses the following technical effects:

[0015] The dual-doped KSrBP2O8:Sm 3+ ,Eu 3+ / Si 4+ Orange - red phosphor, whose light color and luminescence intensity can be regulated by changing the concentration of rare - earth ions. KSrBP2O8:Sm 3+ ,Eu 3+ / Si 4+ The red purity and luminescence intensity of the orange - red phosphor have achieved better effects compared with the existing technologies. When the doping amount of Sm 3+ is 0.005 mol, the peak value of the emission peak of the sample is the largest, presenting obvious orange - red color and having good luminescence performance; with the co - doping of Eu 3+ , the red - light component of the sample is significantly enhanced; when the co - doping amount of Si 4+ is 0.01 mol, the luminescence intensity of the sample increases significantly. The double - doped KSrBP2O8:Sm 3+ ,Eu 3+ / Si 4+ provided by the present invention is a high - brightness red luminescent material that can be effectively excited by near - ultraviolet light.

[0016] The double - doped KSrBP2O8:Sm 3+ ,Eu 3+ / Si 4+ orange - red phosphor with adjustable spectrum provided by the present invention is obtained by using the high - temperature solid - state method and sintering twice to obtain a phosphor with uniform doping and good crystallization. The phosphor co - doped with Sm 3+ ,Eu 3+ or Si 4+ has a higher overall luminescence intensity compared with the phosphor singly doped with Sm 3+ . More importantly, for the phosphor co - doped with Sm 3+ ,Eu 3+ , its color coordinates change with the increase of the Eu 3+ concentration, and its light color gradually changes from the orange - light region to the orange - red - light region, increasing the proportion of the red - light emission of the phosphor.

[0017] Compared with the existing technologies, the preparation method provided by the present invention selects Eu 3+ and Sm 3+ to be double - doped into the KSrBP2O8 lattice. By using the energy transfer interaction between Eu 3+ and Sm 3+ , the continuous tunability of its light color and luminescence intensity is realized. Eu2O3 is a common rare - earth activator raw material, which can improve the luminescence performance of Sm 3+ . In addition, Si 4+ and Sm 3+Double doping in the lattice of KSrBP2O8 can significantly increase the absorption of ultraviolet light by the crystal matrix, thereby increasing the energy transfer efficiency with rare earth ions and achieving a significant improvement in luminescence intensity. Select KSrBP2O8 with a rich lattice and a relatively low synthesis temperature as the matrix, prepare it by a simple high-temperature solid-phase method, optimize its process conditions, and reduce its reaction temperature to reduce energy consumption, obtaining double-doped KSrBP2O8:Sm 3+ ,Eu 3+ / Si 4+ The orange-red phosphor has a higher luminescence intensity and a higher red purity. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0019] Figure 1 In (a) and (b) of FIG., are the X-ray diffraction (XRD) patterns of KSr 3+ doped with different concentrations of Sm in Example 1 1-x BP2O8:xSm 3+ .

[0020] Figure 2 In FIG., are the emission spectra of KSr 3+ doped with different concentrations of Sm in Example 1 1-x BP2O8:xSm 3+ (λ ex = 400 nm) (a) (c) and their luminescence intensities at 600 nm (b) (d).

[0021] Figure 3 In FIG., is the excitation spectrum (λ 0.995 = 600 nm) (a) and the emission spectrum of KSrBP2O8:0.005Sm in Example 1 3+ (λ ex = 400 nm) (b). em

[0022] Figure 4 In FIG., are the chromaticity coordinate (CIE) diagrams of KSr 3+ doped with different concentrations of Sm in Example 1 1-x BP2O8:xSm 3+ .

[0023] Figure 5 In FIG., are the different concentrations of Eu in Example 2 3+ double-doped KSr0.995-y BP2O8: 0.005Sm 3+ , yEu 3+ X-ray diffraction (XRD) pattern.

[0024] Figure 6 For different concentrations of Eu in Example 2 3+ Double-doped KSr 0.995-y BP2O8: 0.005Sm 3+ , yEu 3+ Emission spectrum (λ ex = 400 nm) (a) and its luminescence intensities at 600 nm and 614 nm (b).

[0025] Figure 7 For KSr in Example 2 0.987 BP2O8: 0.005Sm 3+ , 0.008Eu 3+ Excitation spectrum (λ ex = 600 nm) (a) and emission spectrum (b) (λ em = 400 nm).

[0026] Figure 8 For Sm in Example 2 3+ , Eu 3+ Energy level diagram during the energy transfer process.

[0027] Figure 9 For different concentrations of Eu in Example 2 3+ Double-doped KSr 0.995-y BP2O8: 0.005Sm 3+ , yEu 3+ Chromaticity coordinate (CIE) diagram.

[0028] Figure 10 For KSr in Example 2 0.987 BP2O8: 0.005Sm 3+ , 0.008Eu 3+ Scanning electron microscope (SEM) photograph of the phosphor and the corresponding energy-dispersive spectroscopy and its elemental mapping (EDS-mapping) diagram.

[0029] Figure 11 For different concentrations of Si in Example 3 4+ Double-doped KSr 0.995 B 1-z P2O8: 0.005Sm 3+ , zSi 4+ X-ray diffraction (XRD) pattern.

[0030] Figure 12 For different concentrations of Si in Example 34+ Double-doped KSr 0.995 B 1-z P2O8:0.005Sm 3+ ,zSi 4+ emission spectrum diagram (λ ex = 400 nm) (a) and its luminescence intensities at 600 nm and 614 nm (b).

[0031] Figure 13 For KSr 0.995 B 0.96 P2O8:0.005Sm 3+ ,0.04Si 4+ scanning electron microscope (SEM) photograph of the phosphor and the corresponding energy spectrum and its elemental distribution (EDS-mapping) diagram.

[0032] Figure 14 For different concentrations of Si in Example 3 4+ double-doped KSr 0.995 B 1-z P2O8:0.005Sm 3+ ,zSi 4+ chromaticity coordinate (CIE) diagram.

[0033] Figure 15 Schematic diagram of the crystal structure of the KSrBP2O8 matrix.

[0034] Figure 16 For Sm 3+ doped KSr 0.96 BP2O8:0.04Sm 3+ X-ray diffraction (XRD) pattern at different calcination temperatures in Comparative Example 1. Detailed implementation manners

[0035] Now, various exemplary implementation manners of the present invention will be described in detail. This detailed description should not be considered as a limitation of the present invention, but should be understood as a more detailed description of certain aspects, characteristics, and implementation schemes of the present invention.

[0036] It should be understood that the terms described in the present invention are only for describing specific implementation manners and are not used to limit the present invention. Additionally, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded from the range.

[0037] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Although this invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of this invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0038] Without departing from the scope or spirit of the present invention, various modifications and variations can be made to the specific embodiments of the description of the present invention, which will be apparent to those skilled in the art. Other embodiments obtained from the description of the present invention will be apparent to those skilled in the art. The description and examples of the present invention are merely illustrative.

[0039] Regarding the use of "comprising", "including", "having", "containing", etc. herein, they are all open-ended terms, meaning including but not limited to.

[0040] The common luminescence characteristics of rare earth elements are f-f transitions, which mainly occur in the 4f shell transitions of the elements. Under the excitation of ultraviolet light, rare earth ions usually release visible light, which is generated by 4f-4f transitions. Trivalent europium ions (Eu 3+ ) are a common 4f-4f transition doping ion, and its radiation energy can effectively activate the host compound to release orange or red light, corresponding to Eu 3+ in the characteristic transition 5 D0→ 7 F1 magnetic dipole transition and 5 D0→ 7 F2 electric dipole transition. When Eu 3+ is mainly in a non-inversion symmetry center in the lattice, strong red fluorescence emission can be achieved at lattice sites with lower symmetry. Eu 3+ doped red phosphors generally have limited absorption of near-ultraviolet light, so they usually need to be co-doped with sensitizer ions or other rare earth ions to enhance their absorption and achieve spectral tunability, such as Sm 3+ , Eu 3+ mutual energy transfer can enhance its red light emission intensity. SiO2 has a strong ability to absorb excitation energy in the ultraviolet and near-ultraviolet regions, and the incorporation of Si 4+ can effectively enhance the absorption of the material in the near-ultraviolet and blue regions. In order to significantly improve the luminescence intensity of the phosphor, different concentrations of Si 4+ are doped into the KSrBP2O8 matrix.

[0041] The present invention utilizes double rare earth doping of KSrBP2O8:Sm 3+, Eu 3+ / Si 4+ Phosphors are used to achieve continuous tunability of their luminescence intensity and color. By utilizing energy transfer or sensitization between doped ions, the luminescence performance of the phosphors is improved. The luminescent materials prepared by the high-temperature solid-state method have the advantages of simple process and high luminescence intensity, so they are adopted in this invention. The obtained KSrBP2O8:Sm 3+ , Eu 3+ / Si 4+ phosphors can be effectively excited by near-ultraviolet light at 400 nm and can achieve wide regulation of the orange and red light color and luminescence intensity through codoping. Therefore, KSrBP2O8:Sm 3+ , Eu 3+ / Si 4+ phosphors are excellent candidates for luminescent materials for LEDs.

[0042] There are relatively abundant cation lattice sites in KSrBP2O8 and the structure of a special polyanionic dodecagonal ring, which is very conducive to the co-doping of multiple cations. The anionic group of borophosphate has strong absorption in the near-ultraviolet / ultraviolet region, and the metal-oxygen copolymer unit or polyhedron can provide a variety of cation crystal field coordination environments for rare-earth ion doping and substitution. Therefore, the lattice structure and color of KSrBP2O8 phosphors can be designed more diversely. In addition, by using the high-temperature solid-state reaction, a complex borophosphate luminescence system can be obtained only through two-step calcination. The synthesis temperature of the borophosphate system is relatively low, and the product has good crystallinity. This process can be carried out under normal pressure and in an air atmosphere, with simple operation, easily available raw materials, and is suitable for popularization.

[0043] In the first aspect of this invention, an orange-red fluorescent material is provided, with KSrBP2O8 as the matrix and Sm 3+ and M as the activator ions, where M is Eu 3+ or Si 4+ ;

[0044] When M is Eu 3+ , the chemical formula of the orange-red fluorescent material is KSr 1-x-y BP2O8:xSm 3+ ,yEu 3+ ; where 0.001 ≤ x ≤ 0.016, 0.002 ≤ y ≤ 0.010;

[0045] When M is Si 4+ , the chemical formula of the orange-red fluorescent material is KSr 1-x B 1-z P2O8:xSm 3+ ,zSi 4+; wherein, 0.001 ≤ x ≤ 0.016, 0.01 ≤ z ≤ 0.05.

[0046] KSrBP2O8:Sm 3+ ,Eu 3+ / Si 4+ The phosphor is a typical inorganic rare earth luminescent material of borophosphate. After the carbonate, boric acid, phosphate, and rare earth oxide are uniformly mixed, a borophosphate matrix crystal is formed through a high-temperature solid-phase reaction process. Rare earth or other cations are doped into the matrix lattice through their oxides to form a rare earth luminescent material with good crystallization and excellent luminescence performance. Its emission intensity and light color can be adjusted within a wide range by the type and concentration of the doped ions.

[0047] The KSrBP2O8:Sm 3+ ,Eu 3+ / Si 4+ phosphor provided by the present invention contains two activator ions as luminescence centers at the same time, and can improve each other's luminescence brightness and light color purity through energy transfer.

[0048] The rare earth double-doped KSrBP2O8:Sm 3+ ,Eu 3+ phosphor with adjustable spectrum provided by the present invention can be effectively excited by near-ultraviolet light at 400 nm, and exhibits high luminescence intensity and red light purity, and improves the designability of the luminescence performance of the material through double-doped ions.

[0049] In some embodiments of the present invention, when M is Eu 3+ , the chemical formula of the orange-red fluorescent material is KSr 1-x- y BP2O8:xSm 3+ ,yEu 3+ ; wherein, x = 0.001, 0.002, 0.003, 0.004, 0.005, 0.010, 0.04, 0.06, 0.08, 0.10, 0.12, 0.14, 0.16, y = 0.002, 0.004, 0.006, 0.008, 0.010;

[0050] When M is Si 4+ , the chemical formula of the orange-red fluorescent material is KSr 1-x B 1-z P2O8:xSm 3+ ,zSi 4+; wherein, x = 0.001, 0.002, 0.003, 0.004, 0.005, 0.010, 0.04, 0.06, 0.08, 0.10, 0.12, 0.14, 0.16, and z = 0.01, 0.02, 0.03, 0.04, 0.05.

[0051] In some embodiments of the present invention, when M is Eu 3+ the chemical formula of the orange-red fluorescent material is KSr 0.995-y BP2O8:0.005Sm 3+ , yEu 3+ ; wherein, y = 0.002, 0.004, 0.006, 0.008, 0.010;

[0052] When M is Si 4+ the chemical formula of the orange-red fluorescent material is KSr 0.995 B 1-z P2O8:0.005Sm 3+ , zSi 4+ ; wherein, z = 0.01, 0.02, 0.03, 0.04, 0.05.

[0053] In some embodiments of the present invention, when M is Eu 3+ the chemical formula of the orange-red fluorescent material is KSr 0.987 BP2O8:0.005Sm 3+ , 0.008Eu 3+ ;

[0054] When M is Si 4+ the chemical formula of the orange-red fluorescent material is KSr 0.995 B 0.99 P2O8:0.005Sm 3+ , 0.01Si 4+ .

[0055] The second aspect of the present invention provides a method for preparing the above orange-red fluorescent material, comprising the following steps:

[0056] Step 1. Weigh the raw materials according to the chemical formula, then grind and dry them to obtain Powder 1;

[0057] Step 2. Pre-calcine Powder 1 in an air atmosphere, then grind it to obtain Powder 2;

[0058] Step 3. Calcinate Powder 2 in an air atmosphere, then grind it to obtain the orange-red fluorescent material.

[0059] In some embodiments of the present invention, the raw materials are boric acid, ammonium hydrogen phosphate, oxides of doping elements, potassium carbonate, and strontium oxide or strontium carbonate; the ammonium hydrogen phosphate is ammonium dihydrogen phosphate or diammonium hydrogen phosphate; the oxides of doping elements are samarium oxide, europium oxide, and silicon dioxide. In the present invention, boric acid serves as one of the components of the matrix and also as a flux, and the oxides of doping elements serve as activators or sensitizers. When weighing the raw materials, due to the volatility of phosphates, an appropriate overdosage strategy is adopted, such as an overdosage of 5% - 30%, preferably 10%.

[0060] In some embodiments of the present invention, the drying temperature is 40 - 60°C, preferably 60°C. The present invention does not limit the drying time, and it is sufficient to dry the ground powder, for example, drying for 0.5 - 1 h.

[0061] In some embodiments of the present invention, the heating rate of pre - calcination is 1 - 15°C / min, the pre - calcination temperature is 400 - 700°C, and the holding time is 0.5 - 6 h; after the pre - calcination, it is cooled to room temperature; the way of cooling to room temperature is natural cooling or quenching. The present invention pre - calcines in an air atmosphere to remove volatile components such as ammonia and crystal water, so as to better form matrix anions using its phosphorus element.

[0062] In some embodiments of the present invention, the heating rate of pre - calcination is 10°C / min, the pre - calcination temperature is 400°C, and the holding time is 1 - 3 h; after the pre - calcination, it is cooled to room temperature; the way of cooling to room temperature is natural cooling or quenching.

[0063] In some embodiments of the present invention, the heating rate of pre - calcination is 10°C / min, the pre - calcination temperature is 400°C, and the holding time is 2 h; after the pre - calcination, it is cooled to room temperature; the way of cooling to room temperature is natural cooling or quenching.

[0064] In some embodiments of the present invention, the heating rate of calcination is 1 - 15°C / min, the calcination temperature is 700 - 900°C, and the holding time is 1 - 12 h; after the calcination, it is cooled to room temperature; the way of cooling to room temperature is natural cooling or quenching.

[0065] In some embodiments of the present invention, the heating rate of calcination is 10°C / min, the calcination temperature is 700 - 800°C, and the holding time is 1 - 10 h; after the calcination, it is cooled to room temperature; the way of cooling to room temperature is natural cooling or quenching.

[0066] In some embodiments of the present invention, the heating rate of calcination is 10°C / min, the calcination temperature is 800°C, and the holding time is 3 h; after the calcination, it is cooled to room temperature; the way of cooling to room temperature is natural cooling or quenching.

[0067] The present invention obtains the phosphor by sintering the solid mixed powder in two stages, which makes its crystallinity better and is conducive to the effective doping of cations into the matrix lattice.

[0068] The reasons for setting the above reaction temperature, time, and reaction method in the present invention are as follows:

[0069] Appropriate calcination temperature and shorter holding time can save energy consumption as much as possible on the premise of ensuring good crystallinity. High-temperature solid-phase reaction can ensure the full formation and integrity of the lattice to the greatest extent, achieve high brightness and adjustable light color, and the defect situation caused by doping can be qualitatively analyzed, thus facilitating the optimization of process conditions. If not within the above condition range, it will lead to poor crystallinity of the product or even the inability to form the main-phase matrix. For example, when the temperature is lower than 700 °C, the KSrBP2O8 crystal phase cannot be formed or there are obvious impurity peaks in the crystal phase. When the temperature is higher than 950 °C, the sample will show a vitrified state, become a hard block and fuse with the crucible, which is not conducive to grinding into powder for application, and the sample matrix is completely transformed into other phases (Sr2P2O7); similarly, too short or too long reaction time is not conducive to the crystallization of the main-phase matrix.

[0070] In some embodiments of the present invention, in step 1, a grinding aid is further added during the grinding process; the grinding aid is anhydrous ethanol or anhydrous methanol.

[0071] In the present invention, the crucibles used in step 2 pre-sintering and step 3 calcining are ceramic crucibles or corundum crucibles. During pre-sintering and calcining, the crucibles are sintered with or without lids. When grinding in steps 1 to 3, the mortar is a ceramic mortar or an agate mortar.

[0072] The third aspect of the present invention provides an application of the above orange-red fluorescent material in LED luminescent materials.

[0073] The technical solutions of the present invention, unless otherwise specified, are all conventional solutions in the art. The reagents or raw materials used, unless otherwise specified, are all purchased from commercial channels or are publicly available.

[0074] The raw materials, reagents, and equipment used in the examples can all be obtained through commercial channels. All raw materials and reagents can be used directly without additional treatment.

[0075] To better understand the present invention, the content of the present invention will be further clarified below in conjunction with examples, but the content of the present invention is not limited to the following examples.

[0076] Example 1

[0077] KSr 1-x BP2O8:xSm 3+ The preparation steps are as follows:

[0078] Step 1: Weigh potassium carbonate, strontium carbonate, boric acid, ammonium dihydrogen phosphate (add 10% extra according to the stoichiometric ratio to make up for its decomposition loss), and samarium oxide. Among them, strontium carbonate, potassium carbonate, boric acid, and ammonium dihydrogen phosphate are all of analytical purity (purity greater than 99%), and samarium oxide is of 4N high purity (purity of 99.99%). Place the mixed raw materials in a mortar, add a little anhydrous ethanol, mix and grind them evenly. When the powder is ground into a viscous state (the state when anhydrous ethanol is nearly dry), put it into a constant-temperature oven for drying. The drying temperature is 60 °C. After drying for half an hour, take out the mixed powder and place it in a crucible, cover the crucible lid, and pre-burn it in a muffle furnace under an air atmosphere. The pre-burning temperature is 400 °C, the pre-burning time is 2 h, with programmed heating and a heating rate of 10 °C / min. After natural cooling with the furnace, take out the powder from the crucible and grind it thoroughly in a mortar to a fine powder state, that is, obtain the pre-burned precursor powder 2.

[0079] Step 2: Place the precursor powder 2 in a crucible, cover the crucible lid, and calcine it in a muffle furnace under an air atmosphere. The calcination temperature is 800 °C, the calcination time is 3 h, with programmed heating and a heating rate of 10 °C / min. After natural cooling with the furnace, take out the powder from the crucible and grind it thoroughly in a mortar to a fine powder state. The obtained white powder is KSr 1-x BP2O8:xSm 3+ phosphor. The phosphor can emit orange fluorescence when excited by near-ultraviolet light at 400 nm.

[0080] Figure 1 For KSr 3+ BP2O8:xSm 1-x doped with different concentrations of Sm 3+ (x = 0.001, 0.002, 0.003, 0.004, 0.005, 0.010, 0.04, 0.06, 0.08, 0.10, 0.12, 0.14, 0.16), the X-ray diffraction (XRD) patterns are shown. It can be seen from the figure that the main phase of the obtained phosphor is tetragonal KSrBP2O8, and the shapes and positions of the diffraction peaks are basically the same as those of the standard card COD#96-430-2703. The incorporation of Sm 3+ has almost no effect on the crystal structure of KSrBP2O8.

[0081] Figure 2 are the emission spectra of KSr 3+ BP2O8:xSm 1-x doped with different concentrations of Sm 3+ (x = 0.001, 0.002, 0.003, 0.004, 0.005, 0.010, 0.04, 0.06, 0.08, 0.10, 0.12, 0.14, 0.16) (λ ex=(a) and (c) at 400 nm and its luminescence intensity at 600 nm (b) and (d). As can be seen from the figure, its maximum emission is orange light at 600 nm, attributed to Sm 3+ 's electric dipole transition ( 4 G 5 / 2 → 6 H 7 / 2 ), indicating that Sm 3+ doped in the KSrBP2O8 matrix mainly occupies the lattice sites of the non-inversion symmetry center. When the Sm 3+ doping concentration is x = 0.005, its emission intensity reaches the maximum.

[0082] Figure 3 is the excitation spectrum (λ 0.995 BP2O8:0.005Sm 3+ ) of (λ ex = 600 nm) (a) and the emission spectrum (b) (λ em = 400 nm). In the excitation spectrum, the 3+ of Sm 6 H 5 / 2 → 4 F 7 / 2 excitation transition is the strongest, indicating that excitation at 400 nm is the most effective. Under the excitation of 400 nm, the emission spectrum of KSr 0.995 BP2O8:0.005Sm 3+ is located in the range of 500 - 750 nm and consists of four obvious peaks at 565 nm, 600 nm, 650 nm, and 710 nm respectively. These characteristic peaks can be attributed to Sm 3+ from the excited state 4 G 5 / 2 to 6 H J (J = 5 / 2, 7 / 2, 9 / 2, 11 / 2) transitions. According to the selection rules of electric dipole and magnetic dipole transitions 4 G 5 / 2 → 6 H 7 / 2 the transitions at satisfy the selection rule of ΔJ = ±1, so they are caused by electric dipole transitions, 4 G 5 / 2 → 6 H 5 / 2 transitions are caused by magnetic dipole transitions.

[0083] Figure 4 is KSr doped with different concentrations of Sm 3+ 1-x BP2O8:xSm 3+ ​The chromaticity coordinate (CIE) diagram of (x = 0.001, 0.002, 0.003, 0.004, 0.005, 0.010, 0.04, 0.06, 0.08, 0.10, 0.12, 0.14, 0.16). Table 1 is for KSr 1- x BP2O8:xSm 3+ The CIE coordinate values. Combining Table 1 and Figure 4 It can be seen that as the Sm 3+ concentration increases, the CIE coordinate values of the phosphor gradually shift from the orange light region to the orange-red light region, and the color temperature shows a downward trend.

[0084] Table 1 Different concentrations of Sm in Example 1 3+ doped KSr 1-x BP2O8:xSm 3+ The chromaticity coordinate (CIE) values

[0085]

[0086]

[0087] Example 2

[0088] KSr 0.995-y BP2O8:0.005Sm 3+ ,yEu 3+ The preparation steps are as follows:

[0089] Step 1: Weigh raw materials such as potassium carbonate, strontium carbonate, boric acid, ammonium dihydrogen phosphate (add 10% extra according to the stoichiometric ratio to make up for its decomposition loss), samarium oxide, europium oxide, etc. according to the stoichiometric ratio. Among them, strontium carbonate, potassium carbonate, boric acid, and ammonium dihydrogen phosphate are all of analytical purity (purity greater than 99%), and samarium oxide and europium oxide are of 4N grade high purity (purity of 99.99%). Samarium oxide and europium oxide provide double-doped rare earth ions for the phosphor. Place the mixed raw materials in a mortar, add a little anhydrous ethanol, mix and grind them evenly. When the powder is ground into a viscous state (the state when anhydrous ethanol is almost dry), put it into a constant temperature oven for drying. The drying temperature is 60 °C. After drying for half an hour, take out the mixed powder and place it in a crucible, cover the crucible lid, and pre-burn it in a muffle furnace under an air atmosphere. The pre-burning temperature is 400 °C, and the pre-burning time is 2 h. Programmed heating is carried out with a heating rate of 10 °C / min. After natural cooling with the furnace, take out the powder from the crucible and grind it thoroughly in a mortar to a fine powder state, that is, obtain the pre-burned precursor powder 2.

[0090] Step 2: Place the precursor powder 2 in a crucible, cover the crucible lid, and calcine it in a muffle furnace under an air atmosphere. The calcination temperature is 800 °C, the calcination time is 3 h, with a programmed temperature increase at a rate of 10 °C / min. After natural cooling with the furnace, take out the powder from the crucible and grind it thoroughly in a mortar until it becomes a fine powder state. The resulting white powder is KSr 0.995-y BP2O8:0.005Sm 3+ ,yEu 3+ phosphor. When excited by near-ultraviolet light at 400 nm, this phosphor can be observed to emit bright orange-red fluorescence.

[0091] Figure 5 For KSr 3+ BP2O8:0.005Sm 0.995-y BP2O8:0.005Sm 3+ ,yEu 3+ (y = 0.002, 0.004, 0.006, 0.008, 0.010) X-ray diffraction (XRD) patterns. As the Eu 3+ concentration increases, the structure of the sample shows no obvious change compared with the standard card COD#96 - 430 - 2703. The co-doping of Sm 3+ and Eu 3+ also has no significant effect on the crystal structure of KSrBP2O8.

[0092] Figure 6 Are the emission spectra of KSr 3+ BP2O8:0.005Sm 0.995-y BP2O8:0.005Sm 3+ ,yEu 3+ (y = 0.002, 0.004, 0.006, 0.008, 0.010) (λ ex = 400 nm) (a) and their luminescence intensities at 600 nm and 614 nm (b). It can be seen that its maximum emission is at 600 nm, belonging to 4 G 5 / 2 → 6 H 7 / 2 transition. When the Eu 3+ concentration reaches y = 0.008, its fluorescence value reaches the maximum.

[0093] Figure 7 For KSr 0.987 BP2O8:0.005Sm 3+ ,0.008Eu 3+ excitation spectrum (λ ex = 600 nm) (a) and emission spectrum (b) (λ em= 400 nm). Its main emission peak wavelengths still appear at 565 nm, 600 nm, 650 nm, and 710 nm, corresponding to Sm 3+ from the excited state 4 G 5 / 2 to 6 H J (J = 5 / 2, 7 / 2, 9 / 2, 11 / 2) transitions. In other words, doping with a small amount of Eu 3+ ions does not significantly change the position and shape of the Sm 3+ emission peaks. However, as the amount of Eu 3+ incorporated increases, a gradually distinct peak appears around 612 nm, emitting red fluorescence, corresponding to the 3+ electric dipole transition of Eu 5 D0 → 7 F2.

[0094] Figure 8 is the energy level diagram during the energy transfer process of Sm 3+ , Eu 3+ . When excited at 400 nm, Sm 3+ undergoes non-radiative transitions to the 4 G 5 / 2 energy level, and then 4 G 5 / 2 part of the Sm 3+ on the energy level transitions to 6 H 11 / 2 , 6 H 9 / 2 , 6 H 7 / 2 , 6 H 5 / 2 energy levels, corresponding to the narrow peaks at 710 nm, 650 nm, 600 nm, and 565 nm in the emission spectrum respectively. 4 G 5 / 2 the other Sm 3+ on the energy level transfers energy to Eu 3+ through resonance and transitions to the 3+ D0 energy level of Eu 5 . It can be seen from the figure that the energy transferred from Sm 3+ to Eu 3+ increases continuously, and Eu 3+ constantly transitions from the 5 D0 energy level to the 7 F J (J = 1, 2, 3, 4) energy levels. Since the energy of the 3+ G 4 energy level of Sm 5 / 2 is higher than the energy of the 3+ D0 energy level of Eu 5 , so Eu3+ It is difficult to transfer energy to Sm 3+ , so as Eu 3+ is continuously incorporated, the emission peak intensity of Sm 3+ in 4 G 5 / 2 → 6 H 7 / 2 does not increase, but instead decreases.

[0095] Table 2 R / O ratios of Eu 3+ double-doped KSr 0.995-y BP2O8:0.005Sm 3+ , yEu 3+ (y = 0.002, 0.004, 0.006, 0.008, 0.010), that is, the ( 3+ ( 4 G 5 / 2 → 6 H 7 / 2 ) orange-red light, ( 4 G 5 / 2 → 6 H 9 / 2 ) red light emission peak intensity values and the corresponding peak ratio R / O. The larger the ratio, the stronger the red light emission.

[0096] Table 2 R / O ratios of Eu 3+ double-doped KSr 0.995-y BP2O8:0.005Sm 3+ , yEu 3+ at λ em = 400 nm

[0097]

[0098] Figure 9 For Eu 3+ double-doped KSr 0.995-y BP2O8:0.005Sm 3+ , yEu 3+ (y = 0.002, 0.004, 0.006, 0.008, 0.010) chromaticity coordinate (CIE) diagram. Table 3 shows the CIE coordinate values of KSr 0.995-y BP2O8:0.005Sm 3+ , yEu 3 . Combining Table 3 and Figure 9 as shown, compared with the CIE coordinate values of the phosphor without doping Eu 3+ , as Eu 3+With the increase of doping amount, the CIE coordinate value of the phosphor gradually changes from the orange light area to the orange-red light area, and the color temperature generally shows a downward trend.

[0099] Table 3 Different concentrations of Eu in Example 2 3+ Double doped KSr 0.995-y BP2O8:0.005Sm 3+ ,yEu 3+ Color coordinates (CIE) value

[0100]

[0101] Figure 10 KSr 0.987 BP2O8:0.005Sm 3+ , 0.008Eu 3+ The scanning electron microscope (SEM) photo of the phosphor and the corresponding energy spectrum and surface distribution (EDS-mapping) diagram. The sample surface is relatively smooth, indicating that the matrix is ​​well crystallized. K, Sr, B, P, and O are evenly distributed in the sample. Combined with the XRD results, it shows that Sm 3+ and Eu 3+ It was successfully doped into KSrBP2O8 and KSr was successfully synthesized 0.987 Sm 0.005 BP2O8:0.08Eu 3+ .

[0102] Example 3

[0103] Kq 0.995 B 1-z P2O8:0.005Sm 3+ ,zSi 4+ The preparation steps are as follows:

[0104] Step 1: Weigh potassium carbonate, strontium carbonate, boric acid, ammonium dihydrogen phosphate (add 10% more than the stoichiometric ratio to make up for its decomposition loss), samarium oxide, silicon dioxide and other raw materials according to the stoichiometric ratio. Samarium oxide and silicon dioxide provide dual-doped cations for the phosphor. Place the mixed raw materials in a mortar, add a little anhydrous ethanol to mix and grind evenly, and put the powder into a constant temperature oven for drying after it is ground into a viscous state (the anhydrous ethanol is nearly dry). The drying temperature is 60°C. After drying for half an hour, take out the mixed powder and place it in a crucible, cover the crucible cover, and pre-sinter in a muffle furnace in an air atmosphere. The pre-sintering temperature is 400°C, the pre-sintering time is 2h, the temperature is programmed, and the heating rate is 10°C / min. After the furnace is naturally cooled, the powder is taken out from the crucible and fully ground in the mortar to a fine powder state, and the pre-sintered precursor powder 2 is obtained.

[0105] Step 2: Place the precursor powder 2 in a crucible, cover the crucible lid, and calcine it in a muffle furnace under an air atmosphere. The calcination temperature is 800 °C, the calcination time is 3 h, with a programmed temperature increase at a rate of 10 °C / min. After natural cooling with the furnace, take out the powder from the crucible and grind it thoroughly in a mortar until it becomes a fine powder state. The resulting white powder is KSr 0.995 B 1-z P2O8:0.005Sm 3+ ,zSi 4+ . The phosphor can emit bright orange fluorescence when excited by near-ultraviolet light at 400 nm.

[0106] Figure 11 are X-ray diffraction (XRD) patterns of KSr 4+ co-doped with different concentrations of Si 0.995 B 1-z P2O8:0.005Sm 3+ ,zSi 4+ (z = 0.01, 0.02, 0.03, 0.04, 0.05). It can be seen from the figure that the characteristic diffraction peaks of the XRD of the sample basically coincide with those of the standard card COD#96-430-2703. The co-doping of Sm 3+ , Si 4+ also has no significant effect on the crystal structure of KSrBP2O8.

[0107] Figure 12 are emission spectra of KSr 4+ co-doped with different concentrations of Si 0.995 B 1-z P2O8:0.005Sm 3+ ,zSi 4+ (z = 0.01, 0.02, 0.03, 0.04, 0.05) (λ ex = 400 nm) (a) and their luminescence intensities at 600 nm and 614 nm (b). It can be seen that its maximum emission is at 600 nm, belonging to 4 G 5 / 2 → 6 H 7 / 2 transition. When the Si 4+ concentration reaches z = 0.01, its luminescence intensity reaches the maximum, and compared with the sample singly doped with Sm 3+ , its maximum emission intensity is increased by 1.32 times. As the Si 4+ concentration increases, the intensity of the Sm 3+ emission peak gradually decreases.

[0108] Figure 13 is for KSr in Example 3 0.995 B 0.96 P2O8:0.005Sm3+ , 0.04 Si 4+ Scanning electron microscope (SEM) photographs of the phosphor, and the corresponding energy-dispersive spectroscopy (EDS) and EDS mapping diagrams. Sm 3+ and Si 4+ are evenly distributed in the sample, and the surface of the sample is smooth, indicating good crystallization. Combining with XRD shows that Sm 3+ and Si 4+ have been successfully incorporated into KSrBP2O8 and KSr 0.995 B 0.96 P2O8:0.005Sm 3+ , 0.04 Si 4+ has been successfully synthesized.

[0109] Figure 14 are the chromaticity coordinate (CIE) diagrams of KSr 4+ co-doped with different concentrations of Si 0.995 B 1-z P2O8:0.005Sm 3+ , zSi 4+ (z = 0.01, 0.02, 0.03, 0.04, 0.05). Table 4 shows the 0.995 B 1-z P2O8:0.005Sm 3+ , zSi 4+ . Combining Table 4 and Figure 14 it can be seen that as the doping amount of Si 4+ increases, the change trend of the color temperature of the phosphor is not obvious, and the coordinate values are basically located in the orange light region.

[0110] Table 4 shows the chromaticity coordinate (CIE) values of KSr 4+ co-doped with different concentrations of Si 0.995 B 1-z P2O8:0.005Sm 3+ , zSi 4+ in Example 3.

[0111]

[0112]

[0113] Figure 15 is a schematic diagram of the crystal structure of the KSrBP2O8 matrix. KSrBP2O8 belongs to the tetragonal crystal system, and its space group is I-42d, with α = β = γ = 90°,

[0114] Comparative Example 1

[0115] The difference from Example 1 is only that the calcination temperatures in Step 2 are adjusted to 650°C, 700°C, 750°C, 800°C, 850°C, 900°C, and 950°C respectively, and other steps and parameters are the same as those in Example 1. The obtained KSr 0.995 BP2O8:0.005Sm 3+ shows deteriorated performance and a change in the crystallization of the main phase.

[0116] Figure 16 XRD patterns of Sm 3+ doped KSr 0.96 BP2O8:0.04Sm 3+ at different calcination temperatures are shown. When the calcination temperature is 800°C, a matrix with KSrBP2O8 as the main phase is formed. The diffraction peaks of the sample are strong, the appearance is good, and it is easy to grind. When calcined at 650°C, compared with the standard card, the intensity of the main diffraction peak is lower, and there are impurity peaks (* represents the impurity peak of Sr2P2O7), but a matrix with KSrBP2O8 as the main phase is still formed; when the temperature rises to 700°C and 750°C, compared with the standard card, the synthesis of KSrBP2O8 is still not ideal. The main diffraction peak of the sample is slightly higher than that at 600°C, but the intensity of the impurity peaks also increases; when the temperature is further increased to 850°C and 900°C, although a matrix with KSrBP2O8 as the main phase is obtained and the intensity of the main diffraction peak increases, the sample sinters into a harder lump, adheres to the crucible and is not easy to grind, and the diffraction intensity of the impurity peaks also increases further. When the temperature rises to 950°C, the sample matrix is completely converted into Sr2P2O7. In summary, the optimal calcination temperature of the sample is 800°C.

[0117] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. An orange-red fluorescent material, characterized in that: With KSrBP2O8 as the matrix and Sm 3+ and M are activation ions, where M is Eu 3+ or Si 4+ ; When M is Eu 3+ When the chemical formula of the orange-red fluorescent material is KSr 1-x-y BP2O8:xSm 3+ ,yEu 3+ ; Among them, 0.001≤x≤0.016, 0.002≤y≤0.010; When M is Si 4+ When the chemical formula of the orange-red fluorescent material is KSr 1-x B 1-z P2O8:xSm 3+ ,zSi 4+ ; Among them, 0.001≤x≤0.016, 0.01≤z≤0.

05.

2. A method for preparing the orange-red fluorescent material according to claim 1, characterized in that: The following steps are involved: Step 1. Weigh the raw materials according to the chemical formula, grind and dry them to obtain powder 1; Step 2. pre-calcining the powder 1 in an air atmosphere, and then grinding to obtain powder 2; Step 3: calcining the powder 2 in an air atmosphere, and then grinding it to obtain an orange-red fluorescent material.

3. The method for preparing the orange-red fluorescent material according to claim 2, characterized in that: The drying temperature is 40-60°C.

4. The method for preparing the orange-red fluorescent material according to claim 2, characterized in that: The heating rate of the pre-burning is 1-15°C / min, the pre-burning temperature is 400-700°C, and the holding time is 0.5-6h; after the pre-burning is completed, the temperature is lowered to room temperature; the method of lowering the temperature to room temperature is natural cooling or quenching cooling.

5. The method for preparing the orange-red fluorescent material according to claim 2, characterized in that: The heating rate of the calcination is 1-15°C / min, the calcination temperature is 700-900°C, and the insulation time is 1-12h; after the calcination is completed, the temperature is cooled to room temperature; the method of cooling to room temperature is natural cooling or quenching cooling.

6. The method for preparing the orange-red fluorescent material according to claim 2, characterized in that: In the step 1, the grinding process also includes adding a grinding aid; the grinding aid is anhydrous ethanol or anhydrous methanol.

7. Use of the orange-red fluorescent material according to claim 1 in LED luminescent materials.

Images