Method for accurately regulating and controlling morphology of hexagonal-phase NaYF4 up-conversion nanocrystal
By controlling the amount of NaOH and high-temperature treatment, hexagonal NaYF4 nanocrystals were prepared, solving the problem of morphology control and enabling applications in fields such as security anti-counterfeiting, display devices, and solar cells.
Patent Information
- Application Number
- CN202511277769.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-09
- Publication Date
- 2025-12-16
AI Technical Summary
Existing technologies make it difficult to precisely control the morphology of hexagonal NaYF4 upconversion nanocrystals, which limits their application in various fields.
By adding sodium hydroxide aqueous solution and NH4F solution to a mixture of anhydrous ethanol and oleic acid, and then heating with rare earth salts at high temperature, while controlling the amount of NaOH used, hexagonal prism, hexagonal bipyramidal, or hexagonal disk-shaped NaYF4 nanocrystals were prepared.
Precise control of hexagonal NaYF4 nanocrystals was achieved. The preparation method is simple, efficient, and low-cost, and is suitable for fields such as security anti-counterfeiting, display devices, and solar cells.
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Figure CN121134821A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of nanomaterial preparation, and particularly relates to a method for precisely regulating the morphology of hexagonal phase NaYF4 upconversion nanocrystals. BACKGROUND
[0002] Upconversion nanocrystals (such as β-NaYF4:Yb / Er) have important application value in the fields of biological imaging, anti-counterfeiting encryption, solar cells and the like due to their ability to convert low-energy infrared light into high-energy visible / ultraviolet light, and the morphology is one of the core factors affecting the light-emitting efficiency and application performance of the upconversion nanocrystals.
[0003] The surface energy of different crystal faces of the upconversion nanocrystals is significantly different, which leads to a significant difference in the growth rate of different crystal faces, and it is very difficult to accurately control the anisotropy so that it develops in the expected direction. The growth of specific crystal faces needs to be inhibited by ligand or ion adsorption, but the adsorption strength is difficult to quantitatively control, which easily leads to deviation of the morphology from the expectation; at present, hexagonal phase NaYF4 nanocrystals with different morphologies and sizes can be synthesized by different methods, but how to realize the accurate regulation of the morphology of NaYF4 nanocrystals by controlling variables to realize the application in different fields is still a challenge.
[0004] In view of the above limitations and challenges of the morphology regulation technology of upconversion nanomaterials, it is one of the urgent needs in the field to realize high repeatability of the morphology regulation. SUMMARY
[0005] Therefore, some embodiments disclose a method for precisely regulating the morphology of hexagonal phase NaYF4 upconversion nanocrystals, comprising the following steps:
[0006] S1, a first mixed solution of anhydrous ethanol and oleic acid in a volume ratio of 1:1 is added with a 5M sodium hydroxide aqueous solution, and stirred for 40 minutes to obtain a second mixed solution;
[0007] S2, a 2M NH4F solution is added to the second mixed solution, and stirred for 40 minutes to obtain a third mixed solution;
[0008] S3, Y(NO3)3, Yb(NO3)3 and Er(NO3)3 three kinds of rare earth nitrate salts are added to the third mixed solution, and stirred for 40 minutes to obtain a fourth mixed solution; the molar ratio of Y(NO3)3, Yb(NO3)3 and Er(NO3)3 is 80:18:2;
[0009] S4, the fourth mixed solution is heated at 220℃ for 12 hours;
[0010] S5, the heat-treated product is washed and collected to obtain hexagonal phase NaYF4 upconversion nanocrystals.
[0011] Further, the method for precisely controlling morphology of hexagonal phase NaYF4 upconversion nanocrystals disclosed by some embodiments comprises the following steps:
[0012] The method for precisely controlling morphology of hexagonal phase NaYF4 upconversion nanocrystals disclosed by some embodiments comprises the following steps:
[0013] S1, 5mL of anhydrous ethanol and 5mL of oleic acid form a first mixed solution, 1.5mL of 5M sodium hydroxide aqueous solution is added, and stirring is performed for 40min to obtain a second mixed solution;
[0014] S2, 1mL of 2M NH4F solution is added into the second mixed solution, and stirring is performed for 40min to obtain a third mixed solution;
[0015] S3, 0.32mmol of Y(NO3)3, 0.072mmol of Yb(NO3)3, and 0.008mmol of Er(NO3)3 are added into the third mixed solution, and stirring is performed for 40min to obtain a fourth mixed solution;
[0016] S4, the fourth mixed solution is transferred into a 20mL Teflon-lined autoclave and heated at 220℃ for 12h;
[0017] S5, the product after heat treatment is washed and collected to obtain hexagonal phase NaYF4 upconversion nanocrystals with hexagonal prism shape.
[0018] The method for precisely controlling morphology of hexagonal phase NaYF4 upconversion nanocrystals disclosed by some embodiments comprises the following steps:
[0019] S1, 5mL of anhydrous ethanol and 5mL of oleic acid form a first mixed solution, 1.0mL of 5M sodium hydroxide aqueous solution is added, and stirring is performed for 40min to obtain a second mixed solution;
[0020] S2, 1mL of 2M NH4F solution is added into the second mixed solution, and stirring is performed for 40min to obtain a third mixed solution;
[0021] S3, 0.32mmol of Y(NO3)3, 0.072mmol of Yb(NO3)3, and 0.008mmol of Er(NO3)3 are added into the third mixed solution, and stirring is performed for 40min to obtain a fourth mixed solution;
[0022] S4, the fourth mixed solution is transferred into a 20mL Teflon-lined autoclave and heated at 220℃ for 12h;
[0023] S5, the heat treated product is washed and collected to obtain hexagonal phase NaYF4 up-conversion nanocrystals in the shape of hexagonal bipyramids.
[0024] Some embodiments disclose a method for precisely controlling the morphology of hexagonal phase NaYF4 up-conversion nanocrystals, comprising the steps of:
[0025] S1, 5mL of anhydrous ethanol is mixed with 5mL of oleic acid to form a first mixed solution, 0.5mL of a 5M sodium hydroxide aqueous solution is added, and stirring is performed for 40min to obtain a second mixed solution;
[0026] S2, 1mL of a 2M NH4F solution is added to the second mixed solution, and stirring is performed for 40min to obtain a third mixed solution;
[0027] S3, 0.32mmol of Y(NO3)3, 0.072mmol of Yb(NO3)3 and 0.008mmol of Er(NO3)3 are added to the third mixed solution, and stirring is performed for 40min to obtain a fourth mixed solution;
[0028] S4, the fourth mixed solution is transferred to a 20mL Teflon-lined autoclave and heated at 220℃ for 12h;
[0029] S5, the heat treated product is washed and collected to obtain hexagonal phase NaYF4 up-conversion nanocrystals in the shape of hexagonal bipyramids.
[0030] In another aspect, some embodiments disclose hexagonal phase NaYF4 up-conversion nanocrystals obtained by the method for precisely controlling the morphology of hexagonal phase NaYF4 up-conversion nanocrystals disclosed by the embodiments of the present application, and the morphology of the nanocrystals is in the shape of hexagonal prisms, hexagonal bipyramids or hexagonal disks.
[0031] In still another aspect, some embodiments disclose the application of hexagonal phase NaYF4 up-conversion nanocrystals, and the nanocrystals are used for security and anti-counterfeiting, display devices or solar cells.
[0032] The method for precisely controlling the morphology of hexagonal phase NaYF4 up-conversion nanocrystals disclosed by the embodiments of the present application uses oleic acid as a surfactant, precisely adjusts the amount of NaOH, and controls the preparation of hexagonal phase NaYF4 up-conversion nanocrystals in the shape of hexagonal prisms, hexagonal bipyramids and hexagonal disks under the condition of heating at 220℃ for 12h. The preparation method has the advantages of simple operation, high efficiency, good repeatability and low cost. The prepared hexagonal phase NaYF4 up-conversion nanocrystals have good application prospects in the fields of security and anti-counterfeiting, display devices or solar cells, etc. BRIEF DESCRIPTION OF DRAWINGS
[0033] Figure 1 SEM image of β-NaYF4:Yb / Er up-conversion nanocrystals in Example 1;
[0034] Figure 2 SEM image of β-NaYF4:Yb / Er upconversion nanocrystals in Example 2;
[0035] Figure 3 SEM image of β-NaYF4:Yb / Er upconversion nanocrystals in Example 3;
[0036] Figure 4 XRD patterns of β-NaYF4:Yb / Er upconversion nanocrystals in Examples 1-3;
[0037] Figure 5 Morphology comparison of β-NaYF4:Yb / Er upconversion nanocrystals in Examples 1-3. Detailed Implementation
[0038] The term "embodiment" used herein, as an example, is not necessarily to be construed as superior to or better than other embodiments. Performance testing in these embodiments of the invention, unless otherwise specified, employs conventional testing methods in the art. It should be understood that the terminology used in these embodiments is merely for describing particular implementations and is not intended to limit the scope of the disclosure of these embodiments.
[0039] Unless otherwise stated, the technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the embodiments of this invention pertain; other experimental methods and technical means not specifically noted in the embodiments of this invention refer to experimental methods and technical means commonly used by one of ordinary skill in the art.
[0040] The terms “basic” and “approximately” used in this document are to describe small fluctuations. For example, they can mean less than or equal to ±5%, such as less than or equal to ±2%, such as less than or equal to ±1%, such as less than or equal to ±0.5%, such as less than or equal to ±0.2%, such as less than or equal to ±0.1%, such as less than or equal to ±0.05%. Numerical data presented or expressed in range format in this document are used for convenience and brevity only, and should therefore be flexibly interpreted to include not only the explicitly listed values that define the range, but also all independent values or subranges contained within that range. For example, a numerical range of “1–5%” should be interpreted to include not only the explicitly listed values from 1% to 5%, but also the independent values and subranges within the indicated range. Thus, this numerical range includes independent values such as 2%, 3.5%, and 4%, and subranges such as 1%–3%, 2%–4%, and 3%–5%, etc. This principle also applies to ranges that list only one value. Furthermore, this interpretation applies regardless of the width of the range or the characteristics described.
[0041] In this document, including in the claims, the conjunctions, such as "comprise", "include", "have", "contain", "involve", "accommodate" and the like are to be understood as open-ended, i.e. as meaning "including but not limited to". Only the conjunctions "consist of" and "consist only of" are closed conjunctions.
[0042] For better illustrating the content of the present application, numerous specific details are given in the following specific embodiments. Those skilled in the art should understand that the present application can be implemented without some specific details. In the embodiments, some methods, means, instruments, devices and the like which are well known to those skilled in the art are not described in detail, so as to highlight the main idea of the present application.
[0043] The technical features disclosed in the embodiments of the present application can be combined arbitrarily without conflict, and the technical solutions obtained by the combination belong to the content disclosed by the embodiments of the present application.
[0044] In some embodiments, the method for precisely regulating the morphology of hexagonal phase NaYF4 upconversion nanocrystals comprises the following steps:
[0045] S1, in a first mixed solution of anhydrous ethanol and oleic acid with a volume ratio of 1:1, a 5M sodium hydroxide aqueous solution is added and stirred for 40 min to obtain a second mixed solution; generally, NaOH and the surfactant oleic acid undergo an acid-base neutralization reaction to generate the surfactant sodium oleate, and the oleic acid / sodium oleate has selective adsorption performance on different crystal faces of NaYF4. Under the combined action of the surfactant oleic acid and the surfactant sodium oleate, the morphology of the upconversion nanocrystals can be regulated by controlling the amount of a single variable NaOH, and NaYF4 upconversion nanocrystals with different morphologies, such as hexagonal prism, hexagonal bipyramid or hexagonal disc, can be synthesized;
[0046] S2, a 2M NH4F solution is added to the second mixed solution and stirred for 40 min to obtain a third mixed solution; generally, the third mixed solution is a translucent milky white liquid;
[0047] S3, Y(NO3)3, Yb(NO3)3 and Er(NO3)3 three kinds of rare earth nitrate are added to the third mixed solution and stirred for 40 min to obtain a fourth mixed solution; the molar ratio of Y(NO3)3, Yb(NO3)3 and Er(NO3)3 is 80:18:2;
[0048] S4, the fourth mixed solution is heated at 220℃ for 12h;
[0049] S5, the product of the heat treatment is washed and collected to obtain hexagonal phase NaYF4 up-conversion nanocrystals. Generally, centrifugal collection can be used, the centrifugal collection speed is 8000 rpm, and the time is 10 min. The product of the heat treatment is washed with deionized water and ethanol for multiple times in succession, and further centrifugal collection is performed. The collected product is stored in cyclohexane.
[0050] Generally, the first mixed solution obtained by mixing and stirring the surfactant oleic acid and anhydrous ethanol in the embodiments of the present application provides a growth environment of microemulsion for the up-conversion nanocrystals, NaOH provides a sodium source, and simultaneously reacts with the oleic acid to generate the surfactant sodium oleate. The oleic acid and the sodium oleate both contain a hydrophilic carboxylate-COO- and a long-chain lipophilic hydrocarbon group C 17 H 33 -, which together with the reaction precursor (such as rare earth oleate RE(OA)3) form a microemulsion. The oleic acid / sodium oleate pair has selective adsorption properties for different crystal faces of NaYF4, and can realize the control of the morphology. Under the joint action of the surfactant oleic acid and the sodium oleate, the up-conversion nanocrystals with hexagonal prism, hexagonal bipyramid or hexagonal disc morphology are controlled to be synthesized.
[0051] Some embodiments disclose the application of the hexagonal phase NaYF4 up-conversion nanocrystals. The nanocrystals are used in security anti-counterfeiting, display devices or solar cells. For example, the up-conversion nanocrystals are added in the ink, printed on the commodity label or package for anti-counterfeiting, and only under the irradiation of specific 980 nm laser, the preset color pattern is displayed. By using the up-conversion process, high-brightness three primary colors are generated for display devices by exciting low-energy infrared light. The up-conversion nanocrystals are coated on the surface of the solar cell. The near-infrared photons with low energy in the sunlight, which cannot be absorbed by the battery, are “up-converted” into visible photons with high energy, which can be efficiently absorbed by the battery, thereby improving the photoelectric conversion efficiency of the solar cell.
[0052] The technical details are further exemplarily described below in combination with the embodiments.
[0053] Embodiment 1
[0054] The method for precisely controlling the morphology of the hexagonal phase NaYF4 up-conversion nanocrystals in Embodiment 1 comprises the following steps:
[0055] S1, 5 mL of anhydrous ethanol and 5 mL of oleic acid form a first mixed solution, 1.5 mL of a 5M sodium hydroxide aqueous solution is added, and stirring is performed for 40 min to obtain a second mixed solution;
[0056] S2, 1 mL of a 2M NH4F solution is added to the second mixed solution, and stirring is performed for 40 min to obtain a third mixed solution;
[0057] S3, 0.32 mmol Y(NO3)3, 0.072 mmol Yb(NO3)3, 0.008 mmol Er(NO3)3 three kinds of rare earth nitrate were added into the third mixed solution, and stirred for 40 min to obtain a fourth mixed solution;
[0058] S4, the fourth mixed solution was transferred into a 20 mL Teflon-lined autoclave and heated at 220°C for 12 h;
[0059] S5, the heat-treated product was washed and collected to obtain hexagonal β-NaYF4: Yb / Er upconversion nanocrystals.
[0060] Figure 1 The SEM image of the β-NaYF4: Yb / Er upconversion nanocrystals obtained in Example 1 is shown in FIG. 1, which shows that the β-NaYF4: Yb / Er upconversion nanocrystals have a clear hexagonal prism morphology. Figure 1
[0061] Example 2
[0062] The method for precisely regulating the morphology of hexagonal NaYF4 upconversion nanocrystals in Example 2 comprises the following steps:
[0063] S1, 5 mL of anhydrous ethanol and 5 mL of oleic acid were mixed to form a first mixed solution, 1.0 mL of a 5M sodium hydroxide aqueous solution was added, and stirred for 40 min to obtain a second mixed solution;
[0064] S2, 1 mL of a 2M NH4F solution was added into the second mixed solution, and stirred for 40 min to obtain a third mixed solution;
[0065] S3, 0.32 mmol Y(NO3)3, 0.072 mmol Yb(NO3)3, 0.008 mmol Er(NO3)3 three kinds of rare earth nitrate were added into the third mixed solution, and stirred for 40 min to obtain a fourth mixed solution;
[0066] S4, the fourth mixed solution was transferred into a 20 mL Teflon-lined autoclave and heated at 220°C for 12 h;
[0067] S5, the heat-treated product was washed and collected to obtain hexagonal β-NaYF4: Yb / Er upconversion nanocrystals.
[0068] Figure 2 The SEM image of the β-NaYF4: Yb / Er nanocrystals obtained in Example 2 is shown in FIG. 2, which shows that the β-NaYF4: Yb / Er nanocrystals have a clear hexagonal prism morphology. Figure 2
[0069] Example 3
[0070] The method for precisely regulating the morphology of the hexagonal phase NaYF4 upconversion nanocrystals in Example 3 comprises the steps of:
[0071] S1, 5 mL of anhydrous ethanol is mixed with 5 mL of oleic acid to form a first mixed solution, 0.5 mL of a 5M sodium hydroxide aqueous solution is added, and stirring is performed for 40 min to obtain a second mixed solution;
[0072] S2, 1 mL of a 2M NH4F solution is added to the second mixed solution, and stirring is performed for 40 min to obtain a third mixed solution;
[0073] S3, 0.32 mmol of Y(NO3)3, 0.072 mmol of Yb(NO3)3, and 0.008 mmol of Er(NO3)3 are added to the third mixed solution, and stirring is performed for 40 min to obtain a fourth mixed solution;
[0074] S4, the fourth mixed solution is transferred to a 20 mL Teflon-lined autoclave, and heating treatment is performed at 220°C for 12 h;
[0075] S5, the heat-treated product is washed and collected to obtain hexagonal disc-shaped hexagonal phase NaYF4:Yb / Er upconversion nanocrystals.
[0076] Figure 3 It can be seen from the SEM image of the β-NaYF4:Yb / Er upconversion nanocrystals obtained in Example 3 as shown in Figure 3 that the β-NaYF4:Yb / Er upconversion nanocrystals exhibit a clear hexagonal disc-shaped morphology;
[0077] Figure 4 It can be seen from the SEM image of the β-NaYF4:Yb / Er upconversion nanocrystals obtained in Example 3 as shown in Figure 4 that the β-NaYF4:Yb / Er upconversion nanocrystals exhibit a clear hexagonal disc-shaped morphology;
[0078] Figure 5 It can be seen from the SEM image of the β-NaYF4:Yb / Er upconversion nanocrystals obtained in Example 3 as shown in Figure 5 that the β-NaYF4:Yb / Er upconversion nanocrystals exhibit a clear hexagonal disc-shaped morphology;
[0079] The method for precisely regulating the morphology of hexagonal phase NaYF4 up-conversion nanocrystals disclosed by the embodiment of the application can prepare hexagonal phase NaYF4 nanocrystals with hexagonal prism, hexagonal bipyramid and hexagonal disc morphologies respectively by using oleic acid as a surfactant, precisely regulating the amount of NaOH and heating at 220 DEG C for 12 hours, and has the advantages of simple operation, high efficiency, good repeatability and low cost; and the prepared hexagonal phase NaYF4 up-conversion nanocrystals have good application prospects in the fields of security and anti-counterfeiting, display devices or solar cells and the like.
[0080] The technical solutions disclosed in the embodiments of the application and the technical details disclosed in the embodiments are only exemplary to illustrate the inventive concept of the application, and do not constitute a limitation on the technical solutions of the embodiments of the application, and any conventional change, replacement or combination of the technical details disclosed in the embodiments of the application has the same inventive concept as the application, and is within the protection scope of the claims of the application.
Claims
1. A method for precisely controlling the morphology of hexagonal NaYF4 upconversion nanocrystals, characterized in that, Including the following steps: S1. Add a 5M sodium hydroxide aqueous solution to the first mixture formed by anhydrous ethanol and oleic acid in a volume ratio of 1:1, and stir for 40 minutes to obtain the second mixture. S2. Add a 2M NH4F solution to the second mixture and stir for 40 minutes to obtain the third mixture. S3. Add the three rare earth nitrate salts Y(NO3)3, Yb(NO3)3, and Er(NO3)3 to the third mixed solution and stir for 40 minutes to obtain the fourth mixed solution; the molar ratio of Y(NO3)3, Yb(NO3)3, and Er(NO3)3 is 80:18:
2. S4 and the fourth mixed solution were heated at 220℃ for 12 hours; S5. The heat-treated product is washed and collected to obtain hexagonal NaYF4 upconversion nanocrystals.
2. The method for precisely controlling the morphology of hexagonal NaYF4 upconversion nanocrystals according to claim 1, characterized in that, In step S5, the centrifugation speed is 8000 rpm and the time is 10 min.
3. The method for precisely controlling the morphology of hexagonal NaYF4 upconversion nanocrystals according to claim 1, characterized in that, Including the following steps: S1. 5 mL of anhydrous ethanol and 5 mL of oleic acid form the first mixture. 1.5 mL of 5 M sodium hydroxide aqueous solution is added and stirred for 40 min to obtain the second mixture. S2. Add 1 mL of 2 M NH4F solution to the second mixture and stir for 40 min to obtain the third mixture; S3. Add 0.32 mmol Y(NO3)3, 0.072 mmol Yb(NO3)3, and 0.008 mmol Er(NO3)3 to the third mixed solution and stir for 40 min to obtain the fourth mixed solution. S4 and the fourth mixed solution were transferred to a 20 mL Teflon-lined autoclave and heated at 220 °C for 12 h. S5. The heat-treated product is washed and collected to obtain hexagonal prism-shaped hexagonal phase NaYF4 upconversion nanocrystals.
4. The method for precisely controlling the morphology of hexagonal NaYF4 upconversion nanocrystals according to claim 1, characterized in that, Including the following steps: S1. 5 mL of anhydrous ethanol and 5 mL of oleic acid form a first mixture. 1.0 mL of 5 M sodium hydroxide aqueous solution is added and stirred for 40 min to obtain a second mixture. S2. Add 1 mL of 2 M NH4F solution to the second mixture and stir for 40 min to obtain the third mixture; S3. Add 0.32 mmol Y(NO3)3, 0.072 mmol Yb(NO3)3, and 0.008 mmol Er(NO3)3 to the third mixed solution and stir for 40 min to obtain the fourth mixed solution. S4 and the fourth mixed solution were transferred to a 20 mL Teflon-lined autoclave and heated at 220 °C for 12 h. S5. The heat-treated product is washed and collected to obtain hexagonal bipyramidal hexagonal phase NaYF4 upconversion nanocrystals.
5. The method for precisely controlling the morphology of hexagonal NaYF4 upconversion nanocrystals according to claim 1, characterized in that, Including the following steps: S1. 5 mL of anhydrous ethanol and 5 mL of oleic acid form a first mixture. 0.5 mL of 5 M sodium hydroxide aqueous solution is added and stirred for 40 min to obtain a second mixture. S2. Add 1 mL of 2 M NH4F solution to the second mixture and stir for 40 min to obtain the third mixture; S3. Add 0.32 mmol Y(NO3)3, 0.072 mmol Yb(NO3)3, and 0.008 mmol Er(NO3)3 to the third mixed solution and stir for 40 min to obtain the fourth mixed solution. S4 and the fourth mixed solution were transferred to a 20 mL Teflon-lined autoclave and heated at 220 °C for 12 h. S5. The heat-treated product is washed and collected to obtain hexagonal disk-shaped hexagonal phase NaYF4 upconversion nanocrystals.
6. Hexagonal NaYF4 upconversion nanocrystals, obtained by the method for precisely controlling the morphology of hexagonal NaYF4 upconversion nanocrystals as described in any one of claims 1 to 5, wherein the morphology of the nanocrystals is hexagonal prism, hexagonal bipyramidal, or hexagonal disc.
7. The application of the hexagonal NaYF4 upconversion nanocrystals according to claim 6, characterized in that, The nanocrystals are used for security and anti-counterfeiting purposes, display devices, or solar cells.