A Eu 3+ activated Li2Al4B4O 13 Red luminescent material and preparation method and application thereof

Abstract

The present disclosure provides a Eu 3+ activated Li2Al4B4O 13 :xEu 13 ,yF 3+ , wherein x is the mole number of Eu ‑ substituting Li 3+ , and 0.02≤x≤0.16; y is the mole number of F + , which is a compensating additive of O ‑ , wherein F ‑ is used to substitute O 2‑ to compensate the charge imbalance caused by Eu 3+ doping, and y is 1~4 times of x. The present disclosure combines the charge compensation of F ‑ substituting O 2‑ with the solid phase step sintering process, realizes the synchronous improvement of Eu 3+ high doping (x≤0.16) and red light performance, maximizes the retention of F ‑ through the selection of double fluorine sources and briquetting forming technology, and significantly optimizes the process operability and luminescent performance.

Description

Technical Field

[0001] This disclosure belongs to the field of fluorescent materials technology, specifically relating to an Eu... 3+ Activated Li2Al4B4O 13 Red luminescent materials, their preparation methods, and applications. Background Technology

[0002] Rare-earth ion-activated red luminescent materials are a key component of white LED devices, and their performance directly determines the color gamut and energy efficiency of lighting display equipment. Currently, commercially available Eu... 3+ Doped systems (such as Y2O3:Eu) 3+ Y2WO6:Eu 3+ These technologies generally suffer from significant drawbacks: the demanding high-temperature solid-state synthesis conditions (>1400℃) lead to high production costs and increased lattice defects; the emission spectrum's full width at half maximum (FWHM) is >10nm, and the red light purity cannot meet the NTSC color gamut standard; the luminous intensity decays by more than 30% at 150℃, resulting in severe thermal quenching; and the excitation peak is mostly located around 465nm, causing a spectral mismatch with mainstream near-ultraviolet LED chips (emission band 360-400nm), resulting in device energy loss rates exceeding 25%. These technological bottlenecks restrict the development of high-power LED lighting and wide color gamut display devices. Summary of the Invention

[0003] This disclosure aims to at least address one of the technical problems existing in the prior art, and to provide an Eu 3+ Activated Li2Al4B4O 13 Red luminescent materials, their preparation methods, and applications.

[0004] One aspect of this disclosure is to provide an Eu 3+ Activated Li2Al4B4O 13 The red luminescent material has the general chemical formula Li₂Al₄B₄O₂. 13 :xEu 3+ ,yF - , where x is Eu 3+ Replace Li + The number of moles, and 0.02≤x≤0.16; y is F - The number of moles of the compensation addition, the F - Used to replace O 2- To compensate Eu 3+ The charge imbalance caused by doping, and y is 1 to 4 times that of x.

[0005] Optionally, the Li2Al4B4O 13Red luminescent materials emit red light with a main peak at 610-620 nm when excited by near-ultraviolet light (300-420 nm) or blue light (450-480 nm).

[0006] In another aspect of this disclosure, a method for preparing the Li2Al4B4O described above is proposed. 13 A method for using red luminescent materials, the method comprising: Weigh the lithium source, aluminum source, boron source, europium source, and fluorine source according to their stoichiometric ratios; The raw materials are mixed and pre-sintered in air at 300-700°C for 1-3 hours. The pre-sintered powder is pressed into blocks; The block is heated to 800-900°C in air and held at that temperature for 4-10 hours. After cooling, it is ground to obtain pure-phase Eu. 3+ Activated Li2Al4B4O 13 Red luminescent material.

[0007] Optionally, the lithium source is lithium fluoride.

[0008] Optionally, the aluminum source is aluminum oxide and / or aluminum hydroxide.

[0009] Optionally, the boron source is boron trioxide and / or boric acid.

[0010] Optionally, the europium source is europium oxide.

[0011] Optionally, the fluorine source is ammonium fluoride, and the molar amount of the fluorine source is 1 to 4 times that of the lithium source.

[0012] Optionally, the pressure at which the pre-sintered powder is pressed into a block is 10-30 MPa.

[0013] Another aspect of this disclosure proposes an Eu 3+ Activated Li2Al4B4O 13 The application of red luminescent materials, namely Li2Al4B4O 13 Red luminescent materials are used in near-ultraviolet or blue light-excited light-emitting devices, combined with green or blue phosphors or quantum dots, and encapsulated on the surface of near-ultraviolet or blue light-emitting semiconductor chips.

[0014] This disclosure proposes an Eu 3+ Activated Li2Al4B4O 13 Red luminescent material, its preparation method, and applications. The general chemical formula of this red luminescent material is Li₂Al₄B₄O. 13 :xEu 3+ ,yF - , where x is Eu 3+ Replace Li+ The number of moles, and 0.02≤x≤0.16; y is F - The number of moles of the compensation addition, the F - Used to replace O 2- To compensate Eu 3+ The charge imbalance caused by doping, where y is 1 to 4 times that of x. This disclosure uses F... - Replace O 2- The combination of charge compensation and solid-state stepwise sintering process has enabled Eu 3+ Simultaneous improvement of red light performance with high doping (x≤0.16), while maximizing the retention of F through dual fluorine source selection and compaction technology. - The process is highly operable and the luminescent performance is significantly optimized. Attached Figure Description

[0015] Figure 1 Eu, as a specific embodiment of this disclosure 3+ Activated Li2Al4B4O 13 Flowchart of the preparation method of red luminescent materials; Figure 2 A comparison of the XRD diffraction patterns of the samples prepared in Examples 1, 2, and 3 of this disclosure with the X-ray diffraction standard card PDF#36-1241; Figure 3 The excitation and emission spectra of the sample prepared in Example 1 of this disclosure are shown. Figure 4 The luminescence decay curve of the sample prepared in Example 1 of this disclosure; Figure 5 The excitation and emission spectra of the sample prepared in Example 2 of this disclosure are shown. Figure 6 The luminescence decay curve of the sample prepared in Example 2 of this disclosure; Figure 7 The excitation and emission spectra of the sample prepared in Example 3 of this disclosure are shown. Figure 8 This is the luminescence decay curve of the sample prepared in Example 3 of this disclosure. Detailed Implementation

[0016] To enable those skilled in the art to better understand the technical solutions of this disclosure, the disclosure will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain this disclosure and represent a part of the embodiments of this disclosure, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this disclosure without creative effort are within the protection scope of this disclosure.

[0017] One aspect of this disclosure is the proposal of an Eu3+ Activated Li2Al4B4O 13 The red luminescent material has the general chemical formula Li₂Al₄B₄O₂. 13 :xEu 3+ ,yF - , where x is Eu 3+ Replace Li + The number of moles, and 0.02≤x≤0.16; y is F - The number of moles of the compensation addition, the F - Used to replace O 2- To compensate Eu 3+ The charge imbalance caused by doping, and y is 1 to 4 times that of x.

[0018] In this embodiment, boroaluminate Li2Al4B4O 13 The matrix consists of a three-dimensional rigid framework formed by the connection of [AlO4] and [BO4] tetrahedra, and its low-symmetry lattice environment can be Eu. 3+ Providing a strong crystal field splitting theoretically can effectively suppress luminescence quenching and enhance the probability of electric dipole transitions. It is evident that the crystal lattice of the above material is composed of a rigid framework of [AlO4] and [BO4], giving the luminescence high-temperature stability. Based on this, this embodiment further utilizes Eu... 3+ Doped with Li2Al4B4O 13 Medium volumetric efficiency Li + At the lattice sites, precise charge balance is achieved, making high doping feasible; simultaneously, through the synergistic effect of LiF and NH4F dual fluorine sources: LiF provides stable F - NH4F decomposes to produce NH3, forming a reducing atmosphere that inhibits F. - Oxidation and volatilization, F - Replace O 2- It can not only strengthen the lattice strength, but also reduce the symmetry of the crystal field and enhance electric dipole transitions. 5 D0→ 7 F2) Luminous intensity.

[0019] In this embodiment, Li2Al4B4O 13 Red luminescent materials emit red light with a main peak at 610-620 nm when excited by near-ultraviolet light (300-420 nm) or blue light (450-480 nm), with a half-width of less than 5 nm and color purity close to the NTSC standard.

[0020] In this embodiment, the red emission coordinates of the above-mentioned material are close to the NTSC color gamut standard, the [AlO4]-[BO4] rigid framework effectively suppresses high-temperature luminescence quenching, and the excitation spectrum overlaps with the emission peak of the InGaN LED chip. These performance advantages make Li2Al4B4O13 Eu 3+ It has become a red fluorescent material that combines narrowband emission, high thermal stability and high near-ultraviolet excitation, and is suitable for cutting-edge fields such as light-emitting illumination, display, and high color rendering index lighting.

[0021] like Figure 1 As shown, in another aspect of this disclosure, a method for preparing the Li2Al4B4O described above is proposed. 13 Method S100 for red luminescent materials, the method includes the following specific steps S110-S140: S110. Raw material mixing: Weigh the lithium source, aluminum source, boron source, europium source and fluorine source according to the stoichiometric ratio.

[0022] In step S110, the lithium source is lithium fluoride (LiF); the aluminum source is aluminum oxide (Al2O3) and / or aluminum hydroxide (Al(OH)3); the boron source is boron trioxide (B2O3) and / or boric acid (H3BO3); the europium source is europium oxide (Eu2O3); and the fluorine source is ammonium fluoride (NH4F).

[0023] In step S110, the molar amount of fluorine source is 1-4 times that of lithium source. For example, the molar amount of NH4F is 1-4 times that of LiF.

[0024] S120, Pre-sintering: Mix the raw materials and heat them to 300-700℃ in an air atmosphere for pre-sintering, and hold for 1-3 hours.

[0025] In step S120, the pre-sintering temperature can preferably be 300℃, 400℃, 500℃, 600℃, 700℃, etc., and the holding time can preferably be 1 hour, 2 hours, 3 hours, etc.

[0026] S130, Compression molding: Compressing the pre-sintered powder into blocks.

[0027] In step S130, the pressure at which the pre-sintered powder is pressed into a block is 10-30 MPa, for example, preferably 10 MPa, 20 MPa, 30 MPa, etc.

[0028] S140. Heat the block to 800-900℃ in air, hold for 4-10 hours, cool, and then grind to obtain pure phase Eu. 3+ Activated Li2Al4B4O 13 Red luminescent material.

[0029] In step S140, the sintering temperature can preferably be 800℃, 850℃, 900℃, etc., and the holding time can preferably be 4h, 5h, 6h, 7h, 8h, 9h, 10h, etc.

[0030] In the preparation process of this embodiment, F- Replace O 2- The combination of charge compensation and solid-state stepwise sintering process has enabled Eu 3+ Simultaneous improvement of red light performance with high doping (x≤0.16), while maximizing the retention of F through dual fluorine source selection and compaction technology. - A simple sintering process can be used to obtain single-phase products at temperatures below 900℃. This process is energy-efficient, cost-effective, and requires no protective atmosphere, making it suitable for large-scale production. The process is highly operable and its luminescent performance is significantly optimized.

[0031] Another aspect of this disclosure proposes an Eu 3+ Activated Li2Al4B4O 13 Application of red luminescent materials, such as Li2Al4B4O 13 Red luminescent materials are used in near-ultraviolet or blue light-excited light-emitting devices, combined with green or blue phosphors or quantum dots, and encapsulated on the surface of near-ultraviolet or blue light-emitting semiconductor chips.

[0032] Among them, the wavelength of the near-ultraviolet light is 300-420 nm, and the wavelength of the blue light is 450-480 nm.

[0033] In some preferred embodiments, the above-mentioned red luminescent material can be applied to LED phosphors excited by InGaN semiconductor chips under near-ultraviolet radiation (350-410nm).

[0034] The red luminescent material in this embodiment can be combined with green / blue phosphors (or quantum dots) to achieve white light illumination with a high color rendering index under near-ultraviolet light (300-420 nm) or blue light (450-480 nm) excitation, which is especially suitable for indoor lighting and commercial lighting with high color rendering requirements.

[0035] The red luminescent material of this embodiment can also be combined with blue / green luminescent units to serve as the red light source for LED backlighting in displays, achieving a wider color gamut coverage and improving display color saturation. It is suitable for backlight modules of devices such as LCD monitors, televisions, and tablets.

[0036] The Eu will be further explained below with reference to specific embodiments. 3+ Activated Li2Al4B4O 13 Red luminescent materials and their preparation methods: Example 1 According to the chemical formula Li 1.98 Eu 0.02 Al4B4O 13 0.08F -The molar ratios of each element were determined by weighing out 3.54 g of LiF, 0.24 g of Eu₂O₃, 21.5 g of Al(OH)₃, 17.1 g of H₃BO₃, and 0.2 g of NH₄F, which were used as the synthesis raw materials. The mixed raw materials were placed in a corundum crucible and heated to 700°C at 5°C / min in air, holding for 1 hour. The pre-sintered powder was pressed into discs with a diameter of 10 mm under a pressure of 10 MPa. The blocks were then heated to 800°C at 5°C / min in air, holding for 10 hours, and then ball-milled after furnace cooling until the particle size was <10 μm to obtain pure phase Eu. 3+ Activated Li2Al4B4O 13 Red luminescent material.

[0037] See appendix Figure 2 The X-ray powder diffraction pattern of the sample prepared according to Example 1 was compared with that of the standard card PDF#36-1241, and the results showed that the sample was a pure phase material.

[0038] See appendix Figure 3 The images show the excitation and emission spectra of the sample prepared according to Example 1. It can be seen that the sample exhibits excellent excitation in the ultraviolet-blue light range. The strongest emission peak is located at 615 nm, and the emission peak is sharp with pure chromaticity. See appendix Figure 4 The figure shows the luminescence decay curve of the sample prepared according to Example 1. Its luminescence lifetime is 1.75 milliseconds, which is Eu. 3+ The characteristic luminescence decay of ions can meet the needs of luminescent displays without the appearance of afterglow.

[0039] Example 2 According to the chemical formula Li 1.88 Eu 0.12 Al4B4O 13 0.48F - The molar ratios of each element were determined by weighing out 3.07 g of LiF, 1.33 g of Eu₂O₃, 19.7 g of Al(OH)₃, 15.6 g of H₃BO₃, and 0.56 g of NH₄F, which were used as the synthesis raw materials. The mixed raw materials were placed in a corundum crucible and heated to 300 °C at 5 °C / min in air, and held for 3 hours. The pre-sintered powder was pressed into discs with a diameter of 10 mm under a pressure of 30 MPa. The blocks were then heated to 900 °C at 5 °C / min in air, held for 4 hours, cooled in the furnace, and ball-milled until the particle size was <10 μm to obtain pure phase Eu. 3+ Activated Li2Al4B4O 13 Red luminescent material.

[0040] See appendix Figure 2The X-ray powder diffraction pattern of the sample prepared according to Example 2 was compared with that of the standard card PDF#36-1241, and the results showed that the sample was a pure phase material.

[0041] See appendix Figure 5 The images show the excitation and emission spectra of the sample prepared according to Example 2. It can be seen that the sample exhibits excellent excitation in the ultraviolet-blue light range. The strongest emission peak is located at 615 nm, and the emission peak is sharp with pure chromaticity. See appendix Figure 6 The figure shows the luminescence decay curve of the sample prepared according to Example 2 of this paper. Its luminescence lifetime is 1.43 milliseconds, which is Eu. 3+ The characteristic luminescence decay of ions can meet the needs of luminescent displays without the appearance of afterglow.

[0042] Example 3 According to the chemical formula Li 1.84 Eu 0.16 Al4B4O 13 0.16F - The molar ratios of each element were determined by weighing out 3.02 g of LiF, 1.69 g of Eu₂O₃, 12.2 g of Al₂O₃, and 8.35 g of B₂O₃, which were used as the synthesis raw materials. The mixed raw materials were placed in a corundum crucible and heated to 430 °C at 5 °C / min in air, and held for 3 hours. The pre-sintered powder was pressed into discs with a diameter of 10 mm under a pressure of 15 MPa. The blocks were then heated to 820 °C at 5 °C / min in air, held for 5 hours, and then ball-milled after furnace cooling until the particle size was <10 μm to obtain pure phase Eu. 3+ Activated Li2Al4B4O 13 Red luminescent material.

[0043] See appendix Figure 2 The X-ray powder diffraction pattern of the sample prepared according to Example 3 was compared with that of the standard card PDF#36-1241, and the results showed that the sample was a pure phase material.

[0044] See appendix Figure 7 The images show the excitation and emission spectra of the sample prepared according to Example 3. It can be seen that the sample exhibits excellent excitation in the ultraviolet-blue light range. The strongest emission peak is located at 615 nm, and the emission peak is sharp with pure chromaticity. See appendix Figure 8 The figure shows the luminescence decay curve of the sample prepared according to Example 3 of this invention. Its luminescence lifetime is 1.15 milliseconds, which is Eu. 3+ The characteristic luminescence decay of ions can meet the needs of luminescent displays without the appearance of afterglow.

[0045] This disclosure proposes an Eu 3+Activated Li2Al4B4O 13 Red luminescent materials, their preparation methods, and applications have the following advantages compared to existing technologies: First, the boroaluminate matrix disclosed herein has a crystal lattice composed of a rigid framework of [AlO4] and [BO4], with doped Eu... 3 + Ions located in the small Li + At lattice positions, and with precise charge balance achieved, high doping feasibility is realized: Eu in the matrix 3+ The doping concentration is limited (≤5%mol), while this patent uses F - Compensation can increase the doping concentration to 8%mol, breaking through the concentration limit; Second, this disclosure implements a dual-fluorine source strategy: LiF provides stable F - The NH3 gas produced by the decomposition of NH4F forms a local reducing atmosphere, inhibiting the reaction of F. - Oxidation and volatilization; F - Replace O 2- Reduce crystal field symmetry and enhance electric dipole transition ( 5 D0→ 7 F2), enhancing red light intensity and thermal stability; Third, this disclosure uses a simple sintering process to obtain single-phase products at temperatures below 900°C, which is energy-efficient, low-cost, and requires no protective atmosphere, making it suitable for large-scale production.

[0046] It is understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of this disclosure, and this disclosure is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and substance of this disclosure, and these modifications and improvements are also considered to be within the scope of protection of this disclosure.

Claims

1. A Eu 3+ Activated Li2Al4B4O 13 The red luminescent material is characterized by, The chemical formula of the red luminescent material is Li2Al4B4O 13 :xEu 3+ ,yF - , where x is Eu 3+ Replace Li + The number of moles, and 0.02≤x≤0.16; y is F - The number of moles of the compensation addition, the F - Used to replace O 2- To compensate Eu 3+ The charge imbalance caused by doping, and y is 1 to 4 times that of x.

2. The Li2Al4B4O according to claim 1 13 The red luminescent material is characterized by, The Li2Al4B4O 13 Red luminescent materials emit red light with a main peak at 610-620 nm when excited by near-ultraviolet light (300-420 nm) or blue light (450-480 nm).

3. A method for preparing Li2Al4B4O as described in claim 1 or 2 13 The method for using red luminescent materials is characterized by... The method includes: Lithium source, aluminum source, boron source, europium source and fluorine source are weighed according to stoichiometric ratio as raw materials; The raw materials are mixed and pre-sintered in air at 300-700°C for 1-3 hours. The pre-sintered powder is pressed into blocks; The block is heated to 800-900°C in air and held at that temperature for 4-10 hours. After cooling, it is ground to obtain pure-phase Eu. 3+ Activated Li2Al4B4O 13 Red luminescent material.

4. The method according to claim 3, characterized in that, The lithium source is lithium fluoride.

5. The method according to claim 3, characterized in that, The aluminum source is aluminum oxide and / or aluminum hydroxide.

6. The method according to claim 3, characterized in that, The boron source is boron trioxide and / or boric acid.

7. The method according to claim 3, characterized in that, The europium source is europium oxide.

8. The method according to claim 3, characterized in that, The fluorine source is ammonium fluoride, and the molar amount of the fluorine source is 1 to 4 times that of the lithium source.

9. The method according to claim 3, characterized in that, The pressure at which the pre-sintered powder is pressed into a block is 10-30 MPa.

10. An Eu as described in claim 1 or 2 3+ Activated Li2Al4B4O 13 The application of red luminescent materials is characterized by... The Li2Al4B4O 13 Red luminescent materials are used in near-ultraviolet or blue light-excited light-emitting devices, combined with green or blue phosphors or quantum dots, and encapsulated on the surface of near-ultraviolet or blue light-emitting semiconductor chips.

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