Yb < 2 + >-doped scandate green fluorescent powder and preparation method thereof

Abstract

The invention provides Yb < + > doped scandate green fluorescent powder and a preparation method and application thereof, the chemical general formula of the fluorescent powder is A1-mSc2-x-nBxO4: m < + > nYb < 2 + >, A is at least one element of magnesium, calcium, strontium and barium, and B is at least one element of yttrium, aluminum, gallium, indium, antimony, bismuth and lanthanide; according to the invention, a raw material mixture is subjected to high-temperature calcination in a strong reducing atmosphere, and efficient doping and stable luminescence of Yb < 2 + > are successfully realized in an ASc2O4 scandate matrix for the first time. The fluorescent powder can be effectively excited by 300-400 nm ultraviolet light, green light with the main peak being about 530 nm, narrow full width at half maximum and high color purity is emitted, the preparation process is simple, the thermal stability of the product is good, and the fluorescent powder can be widely applied to the fields of high-color-rendering white light LEDs, display backlight, laser illumination, X-ray scintillators and the like.

Description

Technical Field

[0001] This application relates to the field of luminescent materials technology, and more specifically, to a Yb 2+ Doped scandium green phosphor and its preparation method. Background Technology

[0002] Phosphor-converting LEDs (pc-LEDs) are a core technology in the current lighting and display fields. To achieve healthy white light with high color rendering and low blue light hazard, the industry is shifting towards solutions that use ultraviolet chips to excite red, green, and blue phosphors. Combining ultraviolet chips with these phosphors can create a healthy, sunlight-like lighting source with high color rendering and adjustable color temperature. Green phosphor is a crucial component of the three-color phosphor system, and its performance directly determines the light quality, luminous efficacy, and lifespan of the phosphor-converting LED device.

[0003] In current inorganic phosphor systems, Ce 3+ and Eu 2+ These are two of the most mature and efficient light-emitting centers. Their luminescence originates from parity-allowed 5... d -4 f Dipole transitions inherently possess the advantage of high internal quantum efficiency; simultaneously, its 5 d Energy levels are extremely sensitive to the crystal field environment and can be effectively controlled through matrix composition, thus forming a mature matrix and luminescent center adaptation design system. Yb has a similar electronic configuration. 2+ Ions, also capable of generating 5 d -4 f The theoretical basis for the transition is clear, but in practical applications, especially in oxide matrices, two key bottlenecks are encountered: First, the Yb in the precursor... 3+ Ions are extremely difficult to reduce to Yb, which is required for luminescence, in oxide lattices. 2+ Second, even if successfully introduced, Yb 2+ The luminescent energy level is also highly susceptible to nonradiative quenching in oxide environments; this leads to high efficiency Yb 2+ Research and development of oxide-doped phosphors has been stagnant for a long time, and related reports are extremely rare.

[0004] ASc₂O₄ (where A is a divalent alkaline earth metal such as Ca, Sr, or Ba) type scandate matrices are considered a class of highly promising luminescent material carriers due to their high structural rigidity, excellent chemical and thermal stability, and low lattice vibration frequencies. Their crystal structure allows for fine-tuning of the lattice environment and crystal field strength through elemental substitution at the A and Sc sites, thereby providing optimized luminescent sites for dopant ions. Yb 2+ When Yb is introduced into the system as a luminescent center, 2+ 5 d -4f The emission peak position of the transition is extremely sensitive to the crystal field intensity. The ASc2O4 matrix can achieve precise and continuous control of the crystal field intensity through flexible substitution of A-sites and Sc-sites. This provides an ideal platform for directionally obtaining emission spectra in the green light band with narrower half-widths (HWHM), potentially achieving color purity superior to existing commercially available green phosphors. Secondly, regarding material stability, Yb... 2+ The ionic radius of Yb is a better match for the divalent A-site ions in the matrix, and its charge is also consistent with the matrix. This matching is beneficial to Yb. 2+ Stable occupancy in the crystal lattice can reduce lattice defects introduced by doping, thereby potentially improving the thermal quenching properties and long-term stability of the material.

[0005] Based on this, the present invention utilizes the unique advantages of scandium crystal structure to construct a structure suitable for Yb 2+ By utilizing the crystal field environment of the luminescent energy level and employing a strong reduction solid-state synthesis process, a novel class of Yb has been successfully developed. 2+ Doped with scandium phosphor. Summary of the Invention

[0006] To solve the above problems, the present invention provides a Yb 2+ The core of this invention lies in the successful overcoming of Yb doped scandate green phosphor and its preparation method, for the first time, through a specific strong reducing atmosphere solid-phase synthesis process in a structurally stable and highly tunable ASc2O4 type scandate matrix. 3+ The precursor is difficult to reduce to luminescent Yb 2+ And Yb 2+ Overcoming the dual technical challenges of easy quenching in oxides, Yb was successfully developed. 2+ The resulting phosphor exhibits highly efficient green luminescence. It can be effectively excited by 300-400 nm ultraviolet light, achieving narrow-band emission at around 530 nm and producing high-purity green light. It also possesses good thermal stability and simple synthesis process, making it promising for applications in white LEDs, display backlights, laser lighting, and X-ray scintillators.

[0007] In a first aspect, the present invention provides a Yb 2+ A doped scandium green phosphor, characterized in that the chemical composition of the phosphor is A. 1-m Sc 2-x-n B x O4: m + n Yb 2+ Wherein, A is at least one element selected from magnesium, calcium, strontium, and barium, and B is at least one element selected from yttrium, aluminum, gallium, indium, antimony, bismuth, and the lanthanides. x, m and n Must satisfy: 0≤ x <2, 0≤m <0.3, 0≤ n <0.3, 0< m + n <0.5.

[0008] As a preferred option x, m and n Must satisfy 0≤ x <1, 0≤ m <0.1, 0≤ n <0.1, 0.001≤ m + n ≤0.2.

[0009] Preferably, the Yb 2+ It occupies lattice sites at Sc sites and / or A sites in the scandium crystal structure.

[0010] Secondly, the present invention provides a Yb 2+ A method for preparing doped scandium green phosphor, characterized by comprising the following steps: S1: According to the stated chemical formula A 1-m Sc 2-x-n B x O4: m + n Yb 2+ According to the stoichiometry, weigh the raw materials containing A, Sc, B and Yb, and mix them to form a precursor; S2: The precursor is calcined in a reducing atmosphere and cooled to obtain phosphor.

[0011] Preferably, the Sc source, A source and B source in S1 are one or more of oxides, hydroxides, carbonates and bicarbonates containing the corresponding elements, mixed in any proportion.

[0012] Preferably, the Yb source in S1 is one or more of the following: oxides, hydroxides, halides, nitrides, carbonates, and bicarbonates containing Yb, mixed in any proportion.

[0013] Preferably, during the S1 mixing process, a flux is also added to the raw materials. The flux is one or more of alkali metal carbonates, alkali metal bicarbonates, alkali metal oxides, alkali metal halides, alkali metal hydroxides, boric acid, or ammonium chloride, mixed in any proportion.

[0014] Preferably, the reducing atmosphere in S2 is selected from at least one of the following atmospheres: (i) Hydrogen or a mixture of hydrogen and an inert gas; (ii) Carbon monoxide or a mixture of carbon monoxide and an inert gas; (iii) A reducing atmosphere of gases produced by the reaction of carbon-containing substances in air, carbon dioxide or an inert atmosphere.

[0015] Preferably, the S2 calcination treatment is carried out at a temperature of 1100~1700℃ for 2~12 h.

[0016] Thirdly, the present invention provides a method using Yb 2+ Application of doped scandium green phosphor in the fabrication of light-emitting devices.

[0017] In summary, the present invention has at least one of the following beneficial technical effects: 1. This invention overcomes the limitations of Yb 2+ Reduction in oxide matrices is difficult. By utilizing the structural characteristics of scandium systems, a suitable crystal field environment can be constructed to stabilize Yb. 2+ 5 d Energy levels were successfully realized for the first time in an ASc2O4 scandium matrix, yielding Yb 2+ The Yb exhibits high-efficiency luminescence. 2+ The doped scandium phosphor can be excited by ultraviolet light of 300~400 nm to achieve high color purity green light emission with an emission peak of ~530 nm and a half-width of only 72 nm.

[0018] 2. The Yb prepared by this invention 2+ Scandium-doped green phosphors can be synthesized using a conventional solid-state reaction method, achieving a pure-phase product through a single sintering process in a strongly reducing atmosphere. The synthesis temperature is moderate, requiring no high pressure or specialized equipment. The process is simple, conditions are easily controlled, and reproducibility is high, making it particularly suitable for large-scale production. The resulting phosphors exhibit high crystallinity, uniform particle size, and good dispersibility, demonstrating excellent physicochemical and thermal stability. They show minimal luminous intensity decay under high-temperature operating conditions and a long lifespan, fully meeting the stringent reliability requirements of high-power LEDs, laser lighting, and other devices. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 The X-ray diffraction pattern of the phosphor provided in Example 1 of this application is shown; Figure 2 The excitation and emission spectra of the phosphor provided in Example 1 of this application are shown; Figure 3The fluorescence lifetime diagram of the phosphor provided in Example 1 of this application at an excitation wavelength of 360 nm and a monitoring wavelength of 530 nm is shown. Figure 4 The normalized emission spectrum of the phosphor provided in Example 2 of this application under 360 nm excitation is shown. Figure 5 The emission spectrum of the phosphor provided in Example 3 of this application under 360 nm excitation is shown. Figure 6 The emission spectrum of the phosphor provided in Example 4 of this application under 360 nm excitation is shown. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention 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 for illustrative purposes only and are not intended to limit the invention. Based on the content disclosed in this invention, all other embodiments obtained by those skilled in the art without creative effort, as well as any technical solutions obtained by combining the technical features of this invention with existing technology, fall within the protection scope of this invention.

[0022] In the description of the embodiments of the present invention, it should be noted that the terms "first," "second," etc., are used only for distinguishing descriptions and should not be construed as indicating or implying relative importance or the number of indicated technical features. Unless otherwise expressly specified and limited, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art.

[0023] For any techniques or conditions not specified in the embodiments, conventional techniques or conditions known in the art or relevant product instructions may be followed. Reagents or instruments whose manufacturers are not specified can be obtained through legitimate commercial channels. The accompanying drawings are for illustrative purposes only and may not be drawn to scale; they are intended to aid understanding and are not intended to limit the actual form or structure of the product. Identical or similar reference numerals in the drawings represent identical or similar elements or elements with identical or similar functions; redundant descriptions will be omitted.

[0024] Techniques, methods, devices, or materials known in the relevant fields may not be discussed in detail, but should be considered part of this specification where appropriate. Without causing conflict, the technical features involved in different embodiments and examples of this invention can be combined with each other.

[0025] To enable those skilled in the art to better understand the present invention, specific embodiments will be used to illustrate the Yb provided in this application. 2+ The doped scandium green phosphor and its preparation method are further elaborated.

[0026] Example Example 1 In this embodiment, the chemical composition of the prepared material is SrSc2O4:0.01Yb. 2+ The green fluorescent powder is produced through the following steps: Accurately weigh the high-purity raw materials according to stoichiometric ratio: strontium carbonate (SrCO3, 99.9%), scandium oxide (Sc2O3, 99.9%), and ytterbium oxide (Yb2O3, 99.99%). Grind and mix these raw materials thoroughly in a mortar to obtain a precursor mixture. Place this mixture into an open alumina crucible, then place the crucible inside a ceramic boat lined with carbon powder, and cover the boat. Place the assembled ceramic boat into a box furnace and calcine it under static air atmosphere at 1400℃ for 6 hours. After calcine, allow the sample to cool naturally to room temperature with the furnace. Remove the sample and lightly grind it to obtain the desired phosphor powder.

[0027] The obtained samples were characterized for phase and luminescence properties, and the X-ray diffraction (XRD) patterns are shown below. Figure 1 As shown, all diffraction peaks are in agreement with the SrSc2O4 standard card, indicating the successful synthesis of a pure-phase scandium matrix, Yb 2+ The doping did not introduce any impurity phase. The fluorescence spectrum is as follows: Figure 2 As shown, this phosphor can be effectively excited by ultraviolet light in the 300–400 nm range. Under 360 nm excitation, it exhibits bright green emission, with an emission spectrum covering a narrow band from 450 to 650 nm. The strongest emission peak is located at 530 nm, with a full width at half maximum (FWHM) of 72 nm and CIE 1931 color coordinates of (0.286, 0.599). Its fluorescence decay curve under 360 nm excitation and 530 nm emission wavelength monitoring is shown below. Figure 3 As shown, the fluorescence lifetime calculated by fitting is 9.20 μs.

[0028] Example 2 This embodiment modulates Yb 2+ Doping concentration was used to prepare a series of SrSc2O4 with the following chemical composition: x Yb 2+ ( xGreen phosphors with concentrations of 0.002, 0.005, 0.01, 0.02, and 0.05 were used to investigate the effect of doping concentration on their luminescence properties. SrCO3 (99.9%), Sc2O3 (99.9%), and Yb2O3 (99.99%) were accurately weighed according to the stoichiometric ratios of the five chemical formulas. For each ratio, the weighed raw materials were thoroughly ground and mixed evenly to obtain their respective precursors. Each precursor was placed in an open alumina crucible, which was then placed in a ceramic boat filled with carbon powder and sealed. The ceramic boats were placed in a box furnace and calcined in air at a temperature of 1400℃ for 6 hours, followed by natural cooling to room temperature. The cooled samples were then ground to obtain five different Yb2O3 precursors. 2+ Phosphor samples with varying doping concentrations.

[0029] The samples were tested using a fluorescence spectrometer, and their normalized emission spectra under 360 nm ultraviolet light excitation are as follows: Figure 4 As shown. All samples emitted bright green light under 360 nm excitation, and the emission spectra were all narrow bands covering 450–650 nm. With Yb 2+ As the doping concentration x increases from 0.002 to 0.05, the emission spectrum exhibits a regular change; the position of the main emission peak shows a slight redshift with increasing doping concentration. This is because at higher concentrations, Yb²⁺… + The enhanced interionic interactions alter the surrounding crystal field environment.

[0030] This embodiment demonstrates that by adjusting Yb 2+ The doping amount can effectively control the emission peak position and intensity of the phosphor within a certain range, providing an important basis for optimizing material performance for specific applications.

[0031] Example 3 The chemical composition of the luminescent material in this embodiment is SrSc2O4:0.01Yb. 2+ Boric acid was added as a sintering aid. According to the stoichiometric ratio, raw materials SrCO3 (99.9%), Sc2O3 (99.9%), and Yb2O3 (99.99%) were accurately weighed, and 3 wt.% boric acid was added as a flux. The above raw materials were ground and mixed evenly, placed in an alumina crucible (without a lid), and then placed into a porcelain boat filled with carbon powder. The porcelain boat was then covered and calcined in air at 1400℃ for 6 hours. After cooling in the furnace, the mixture was ground to obtain the desired phosphor. The phosphor obtained in Example 3 was analyzed using a fluorescence spectrometer. Its emission spectrum under 360 nm excitation was compared with the emission spectrum in Example 1. Figure 5 As shown, adding boric acid as a sintering aid can significantly improve the luminescence intensity of this phosphor.

[0032] Example 4 The luminescent material in this embodiment has the chemical formula SrSc. 1.5 Y 0.5 O4:0.01Yb 2+ According to the stoichiometric ratio, accurately weigh the raw materials SrCO3 (99.9%), Sc2O3 (99.9%), Y2O3 (99.9%), and Yb2O3 (99.99%). Grind and mix the above raw materials evenly, place them into an alumina crucible without a lid, and then place them into a porcelain boat filled with carbon powder. Cover the porcelain boat with a lid and calcine it in air at a temperature of 1400℃ for 6 hours. After cooling with the furnace, grind to obtain the desired phosphor. Analyze the phosphor obtained in Example 4 using a fluorescence spectrometer. Its emission spectrum under 360 nm excitation is as follows: Figure 5 As shown.

[0033] Example 5 The chemical formula of the luminescent material in this embodiment is Sr. 0.8 Ca 0.2 Sc2O4:0.01Yb 2+ According to the stoichiometric ratio, accurately weigh the raw materials SrCO3 (99.9%), CaCO3 (99.9%), Sc2O3 (99.9%), and Yb2O3 (99.99%). Grind and mix the above raw materials evenly, place them into an alumina crucible without a lid, and then place them into a porcelain boat filled with carbon powder. Cover the porcelain boat with a lid and calcine it in air at a temperature of 1400℃ for 6 hours. After cooling with the furnace, grind to obtain the desired phosphor. The emission spectrum shape of this embodiment is similar to that of Example 1, with a slight redshift of the strongest emission peak.

[0034] Example 6 The chemical formula of the luminescent material in this embodiment is Sr. 0.5 Ba 0.5 Sc2O4:0.01Yb 2+ According to the stoichiometric ratio, accurately weigh the raw materials SrCO3 (99.9%), BaCO3 (99.9%), Sc2O3 (99.9%), and Yb2O3 (99.99%). Grind and mix the above raw materials evenly, place them into an alumina crucible without a lid, and then place them into a porcelain boat filled with carbon powder. Cover the porcelain boat with a lid and calcine it in air at a temperature of 1400℃ for 6 hours. After cooling with the furnace, grind to obtain the desired phosphor. The emission spectrum shape of this embodiment is similar to that of Example 1, with the strongest emission peak red-shifted.

[0035] Example 7 The luminescent material in this embodiment has the chemical formula SrSc. 1.5 Lu 0.5O4:0.01Yb 2+ According to the stoichiometric ratio, accurately weigh the raw materials SrCO3 (99.9%), Sc2O3 (99.9%), Lu2O3 (99.9%), and Yb2O3 (99.99%). Grind and mix the above raw materials evenly, place them into an alumina crucible without a lid, and then place them into a porcelain boat filled with carbon powder. Cover the porcelain boat with a lid and calcine it in air at a temperature of 1400°C for 6 hours. After cooling with the furnace, grind to obtain the desired phosphor. The emission spectrum of this embodiment is similar to that in Example 1.

[0036] Example 8 The luminescent material in this embodiment has the chemical formula SrSc. 1.8 Al 0.2 O4:0.01Yb 2+ According to the stoichiometric ratio, accurately weigh the raw materials SrCO3 (99.9%), Sc2O3 (99.9%), Al2O3 (99.9%), and Yb2O3 (99.99%). Grind and mix the above raw materials evenly, place them into an alumina crucible without a lid, and then place them into a porcelain boat filled with carbon powder. Cover the porcelain boat with a lid and calcine it in air at a temperature of 1400°C for 6 hours. After cooling with the furnace, grind to obtain the desired phosphor. The emission spectrum of this embodiment is similar to that in Example 1.

[0037] In summary, this application has systematically verified the Yb through a series of embodiments. 2+ The feasibility, performance tunability, and process optimization potential of doped scandate green phosphors. Example 1: SrSc2O4:0.01Yb was successfully synthesized via carbothermal reduction. 2+ Phosphors were used, demonstrating that they could achieve high-purity green emission with a peak at 530 nm and a full width at half maximum (FWHM) of 72 nm under 360 nm UV excitation. Example 2 involved changing Yb... 2+ The doping concentration (x = 0.002~0.05) demonstrated that the emission peak position and intensity are adjustable with concentration, and the optimal doping range was determined. Example 3 further shows that adding an appropriate amount of boric acid flux can significantly improve the luminescence intensity without changing the emission spectrum characteristics. All examples collectively demonstrate that the material system and preparation method provided by this invention have the characteristics of good process repeatability, controllable performance, and ease of optimization, laying a solid experimental foundation for their practical application in fields such as solid-state lighting and displays.

[0038] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0039] Although preferred embodiments of the present application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the embodiments of the present application.

[0040] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or terminal device. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or terminal device that includes said element.

[0041] The above describes a Yb provided in this application. 2+ The doped scandium green phosphor and its preparation method are described in detail. Specific examples are used to illustrate the principles and implementation methods of this application. The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A Yb 2+ Doped scandium green phosphor, characterized in that, The chemical composition of the phosphor is A 1-m Sc 2-x- n B x O4: m + n Yb 2+ Wherein, A is at least one element selected from magnesium, calcium, strontium, and barium, and B is at least one element selected from yttrium, aluminum, gallium, indium, antimony, bismuth, and the lanthanides. x, m and n Must satisfy: 0≤ x <2, 0≤ m <0.3, 0≤ n <0.3, 0< m + n <0.

5.

2. A Yb according to claim 1 2+ Doped scandium green phosphor, characterized in that, The Yb 2+ It occupies lattice sites at Sc sites and / or A sites in the scandium crystal structure.

3. A Yb 2+ A method for preparing doped scandium green phosphor, characterized in that, Includes the following steps: S1: According to the stated chemical formula A 1-m Sc 2-x-n B x O4: m + n Yb 2+ According to the stoichiometry, weigh the raw materials containing A, Sc, B and Yb, and mix them to form a precursor; S2: The precursor is calcined in a reducing atmosphere and cooled to obtain phosphor.

4. A Yb according to claim 3 2+ A method for preparing doped scandium green phosphor, characterized in that, The Sc source, A source, and B source in S1 are composed of one or more of the following: oxides, hydroxides, carbonates, and bicarbonates containing the corresponding elements, mixed in any proportion.

5. A Yb according to claim 3 2+ A method for preparing doped scandium green phosphor, characterized in that, The Yb source in S1 is composed of one or more of the following: oxides, hydroxides, halides, nitrides, carbonates, and bicarbonates containing Yb, mixed in any proportion.

6. A Yb according to claim 3 2+ A method for preparing doped scandium green phosphor, characterized in that, In the S1 mixing process, a flux is also added to the raw materials. The flux is composed of one or more of the following: alkali metal carbonates, alkali metal bicarbonates, alkali metal oxides, alkali metal halides, alkali metal hydroxides, boric acid, or ammonium chloride, mixed in any proportion.

7. A Yb according to claim 3 2+ A method for preparing doped scandium green phosphor, characterized in that, The reducing atmosphere in S2 is selected from at least one of the following atmospheres: (i) Hydrogen or a mixture of hydrogen and an inert gas; (ii) Carbon monoxide or a mixture of carbon monoxide and an inert gas; (iii) A reducing atmosphere of gases produced by the reaction of carbon-containing substances in air, carbon dioxide or an inert atmosphere.

8. A Yb according to claim 3 2+ A method for preparing doped scandium green phosphor, characterized in that, The S2 calcination treatment is carried out at a temperature of 1100~1700℃ for 2~12 h.

9. Using Yb as described in any one of claims 1 or 2 2+ Application of doped scandium green phosphor in the fabrication of light-emitting devices.

Images