Composite nanomaterial, preparation method and application thereof

Abstract

The application discloses a kind of composite nanomaterial and its preparation method and application, belong to luminescent composite nanomaterial technical field.Composite nanomaterial includes luminescent nanomaterial and carbon quantum dots (CDs);The molecular formula of luminescent nanomaterial is Ca5 (PO4) 3OH:x%Eu 3+ / y%Tb 3+ Wherein, y% is 0%‑90%, x% is 0%‑90%, x and y are not simultaneously 0.The composite nanomaterial provided by the application has red light emission peaks at 590nm and 615nm under the excitation wavelength of 395nm;Under the excitation wavelength of 371nm, it has blue light emission peak at 453nm, green light emission peaks at 490nm and 545nm, and red light emission peaks at 590nm and 615nm, and can be applied in the fields of anti-counterfeiting, white light LED and temperature sensing, and has simple preparation process, low cost and is conducive to realizing industrialized mass production.

Description

Technical Field

[0001] This invention belongs to the field of luminescent composite nanomaterials technology, specifically relating to a composite nanomaterial, its preparation method, and its application. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Currently, the application of nanomaterials in white LEDs, temperature measurement, and anti-counterfeiting fields faces bottlenecks. In temperature measurement, the core challenge lies in the imbalance between signal stability, ease of reading, and cost: the temperature response signals of many materials are easily affected by environmental interference and drift, and complex data often requires sophisticated instruments for analysis, making rapid, portable, real-time measurement difficult. Furthermore, high manufacturing costs limit widespread application. In anti-counterfeiting, a dilemma arises where security and ease of use are difficult to achieve simultaneously: simple and easily identifiable features are easily counterfeited. In white LEDs, most solutions lack sufficient red and green components in their spectra, resulting in poor color rendering, and phosphors are prone to performance degradation over time and temperature, causing color drift and affecting white light stability. These three challenges collectively highlight the difficulties nanomaterials face in achieving stable, easy-to-use, and low-cost practical applications beyond their superior performance. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a composite nanomaterial, its preparation method, and its application. The luminescent composite nanomaterial provided by the present invention can be used in white LEDs, anti-counterfeiting, or temperature sensing, solving the problems of complex preparation processes, high costs, limited temperature measurement range, and easy counterfeiting of anti-counterfeiting technologies in existing technologies. Furthermore, the luminescent composite nanomaterial exhibits good stability.

[0005] The composite nanomaterial provided by this invention is a luminescent composite nanomaterial, comprising Ca5(PO4)3OH:Eu 3+ Ca5(PO4)3OH:Tb 3+ Ca5(PO4)3OH:Eu 3+ / Tb 3+Nanoparticles and carbon quantum dots (CDs, also known as carbon dots). The luminescent composite nanomaterials of this invention exhibit red emission peaks at 590 nm and 615 nm under an excitation wavelength of 395 nm; blue emission peaks at 453 nm under an excitation wavelength of 371 nm; green emission peaks at 490 nm and 545 nm; and red emission peaks at 590 nm and 615 nm. This allows for applications in anti-counterfeiting, white LEDs, and temperature sensing. Furthermore, the fabrication process is simple and low-cost, facilitating large-scale industrial production.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] In a first aspect, the present invention provides a composite nanomaterial, including a luminescent nanomaterial; the molecular formula of the luminescent nanomaterial is Ca5(PO4)3OH:x%Eu. 3+ / y%Tb 3+ Tb 3+ The doping concentration, i.e., y% is 0%~90%, preferably 0.1%~90%, Eu 3+ The doping concentration, i.e., x%, is 0%~90%, preferably 0.1%~90%; x and y cannot be 0 at the same time.

[0008] It also includes carbon quantum dots, carbon quantum dots and luminescent nanomaterials Ca5(PO4)3OH:Eu 3+ / Tb 3+ The mass ratio is 0.1:(1~50).

[0009] Secondly, the present invention provides a method for preparing the above-mentioned composite nanomaterials, comprising:

[0010] The luminescent nanomaterial Ca5(PO4)3OH:x%Eu 3+ / y%Tb 3+ It is obtained by mixing with carbon quantum dots (CDs).

[0011] Thirdly, the present invention provides the application of the above-mentioned composite nanomaterials in white LEDs, anti-counterfeiting and / or temperature sensing.

[0012] Fourthly, the present invention provides a white luminescent composite nanomaterial, wherein the material is the aforementioned composite nanomaterial. The composite nanomaterial comprises a luminescent nanomaterial and carbon quantum dots (CDs); the luminescent nanomaterial is Ca5(PO4)3OH:Eu 3+ / Tb 3+ .

[0013] Fifthly, the present invention provides a white LED comprising the above-mentioned white luminescent composite nanomaterial or the above-mentioned composite nanomaterial composed of luminescent nanomaterial and carbon quantum dots (CDs); wherein the luminescent nanomaterial is Ca5(PO4)3OH:Eu 3+ / Tb 3+ .

[0014] In a sixth aspect, the present invention provides a temperature sensor comprising the aforementioned composite nanomaterial.

[0015] In a seventh aspect, the present invention provides an anti-counterfeiting material, said anti-counterfeiting material comprising the aforementioned carbon quantum dots (CDs) and the aforementioned luminescent nanomaterial Ca5(PO4)3OH:x%Eu. 3+ / y%Tb 3+ And the aforementioned composite nanomaterials. Preferably, the aforementioned composite nanomaterials can achieve multiple anti-counterfeiting measures.

[0016] One or more of the above technical solutions have the following advantages or beneficial effects:

[0017] (1) The luminescent nanomaterial provided by this invention is Ca5(PO4)3OH:Eu 3+ At an excitation wavelength of 395 nm, it emits red light, and the doping concentration is related to the emission intensity, thus exhibiting anti-counterfeiting properties; the luminescent nanomaterial is Ca5(PO4)3OH:Tb. 3+ At an excitation wavelength of 371 nm, it emits green and red light, and the doping concentration is related to the emission intensity, thus exhibiting anti-counterfeiting properties; the luminescent nanomaterial is Ca5(PO4)3OH:Eu 3+ / Tb 3+ The light emitted red and green light at a 371nm excitation wavelength, with the doping concentration affecting the emission intensity, thus providing an anti-counterfeiting effect; the carbon dots emitted blue light at a 371nm excitation wavelength, also providing an anti-counterfeiting effect; the carbon dots react with Ca5(PO4)3OH:Eu 3 + / Tb 3+ The mixed composite nanoparticles emit red, green, and blue light at an excitation wavelength of 371 nm, enabling multiple anti-counterfeiting measures.

[0018] (2) The luminescent composite nanomaterials provided by the present invention have small particle size and simple detection method, which can effectively reduce the industrial detection process.

[0019] (3) The luminescent composite nanomaterials provided by the present invention have a simple preparation process and low cost, which is conducive to realizing large-scale industrial production.

[0020] (4) The luminescent composite nanomaterials prepared in this invention can be applied not only to temperature sensing, but also to white LEDs and anti-counterfeiting applications, demonstrating a wide range of applications. When applied to white LEDs, the luminescent nanomaterials Ca5(PO4)3OH:Eu 3+ / Tb 3+ The doping concentrations of terbium and europium in the carbon quantum dots and luminescent nanomaterials Ca5(PO4)3OH:Eu 3+ / Tb 3+ The mass ratio is crucial; it requires specific conditions to emit white light, specifically cool white light. In applications such as temperature sensing, carbon quantum dots (CDs) and luminescent nanomaterials (Ca5(PO4)3OH:Eu) are used. 3+ / Tb 3+ As well as carbon quantum dots (CDs) and luminescent nanomaterials Ca5(PO4)3OH:Eu 3+ / Tb 3+ The resulting composite nanomaterial exhibits temperature sensing properties, with fluorescence emission intensity decreasing as temperature increases.

[0021] (5) The white light emitting composite nanomaterial provided by the present invention emits white light at an excitation wavelength of 371 nm, and the white light emitting effect is obvious. Attached Figure Description

[0022] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0023] Figure 1 The Ca5(PO4)3OH:70%Eu prepared in Example 1 of this invention 3+ Scanning electron microscope image of nanoparticles;

[0024] Figure 2 The Ca5(PO4)3OH:70%Eu prepared in Example 1 of this invention 3+ X-ray diffraction pattern of nanoparticles;

[0025] Figure 3 This is a transmission electron microscope image of carbon quantum dots from Example 4 of the present invention;

[0026] Figure 4 The Ca5(PO4)3OH:70%Eu prepared in Example 1 of this invention 3+ Excitation spectrum of nanoparticles;

[0027] Figure 5 Different Eu values ​​in Embodiment 1 of the present invention 3+ Ca5(PO4)3OH:Eu prepared at different doping concentrations 3+Emission spectrum of nanoparticles under 395 nm excitation;

[0028] Figure 6 The Ca5(PO4)3OH:70%Eu prepared in Example 1 of this invention 3+ Emission spectrum of nanoparticles under 371 nm excitation;

[0029] Figure 7 Preparation of Eu with different doping methods in Example 1 of the present invention 3+ The fluorescence intensity change at 590 nm for Ca5(PO4)3OH nanoparticles of a certain concentration excited at 395 nm.

[0030] Figure 8 The Ca5(PO4)3OH:70%Tb prepared in Example 2 of this invention 3+ Excitation spectrum of nanoparticles;

[0031] Figure 9 Different Tb values ​​in Embodiment 2 of the present invention 3+ Ca5(PO4)3OH:Tb prepared at different doping concentrations 3+ Emission spectrum of nanoparticles excited at 371 nm;

[0032] Figure 10 Preparation of Tb doped with different amounts in Example 2 of the present invention 3+ The fluorescence intensity change at 545 nm for Ca5(PO4)3OH nanoparticles of a certain concentration under 371 nm excitation;

[0033] Figure 11 The Ca5(PO4)3OH:Eu prepared in Example 3 of this invention 3+ / Tb 3+ Excitation spectrum of nanoparticles;

[0034] Figure 12 Eu in Embodiment 3 of the present invention 3+ and Tb 3+ Ca5(PO4)3OH:Eu prepared with different doping amounts 3+ / Tb 3+ Emission spectrum of nanoparticles excited at 371 nm;

[0035] Figure 13 The Ca5(PO4)3(OH):Eu prepared in Example 3 of this invention 3+ / Tb 3+ Colorimetric diagram (CIE diagram) of nanoparticles;

[0036] Figure 14 The Ca5(PO4)3OH:Eu prepared in Example 3 of this invention 3+ / Tb3+ Emission spectrum of nanoparticles excited at 395 nm;

[0037] Figure 15 The emission spectrum of carbon quantum dots prepared in Example 4 of this invention under 371 nm excitation;

[0038] Figure 16 The CIE diagram of the carbon quantum dots prepared in Example 4 of this invention;

[0039] Figure 17 The emission spectrum of the composite nanoparticles prepared in Example 5 of this invention under 371 nm excitation;

[0040] Figure 18 The emission spectrum of the composite nanoparticles prepared in Example 5 of the present invention as a function of temperature under 371 nm excitation;

[0041] Figure 19 The graph shows the linear fit of the fluorescence intensity at 590 nm as a function of temperature for the composite nanoparticles prepared in Example 5 of this invention.

[0042] Figure 20 The graph shows the linear fit of the fluorescence intensity at 615 nm as a function of temperature for the composite nanoparticles prepared in Example 5 of this invention.

[0043] Figure 21 These are anti-counterfeiting images of inks prepared from various materials of the present invention under specific excitation wavelengths; wherein, (a) Ca5(PO4)3OH:Eu 3+ (a) Anti-counterfeiting image of luminescent composite nanomaterial ink excited at 395 nm; (b) Anti-counterfeiting image of luminescent composite nanoparticle ink prepared in Example 5 excited at 371 nm; (c) Ca5(PO4)3OH:Eu prepared in Example 3. 3+ / Tb 3+ Anti-counterfeiting image of luminescent composite nanomaterial ink excited at 371nm, (d) Ca5(PO4)3OH:Tb prepared in Example 2 3+ Luminescent composite nanomaterial ink, (e) Anti-counterfeiting image of CDs ink prepared in Example 4 excited at 371 nm;

[0044] Figure 22 The CDs and Ca5(PO4)3OH:Eu prepared in Example 6 of this invention 3+ / Tb 3+ CIE diagram of composite nanoparticles ground and mixed at a mass ratio of 0.1:6.0;

[0045] Figure 23 The CDs and Ca5(PO4)3OH:Eu prepared in Example 6 of this invention 3+ / Tb 3+CIE diagram of composite nanoparticles ground and mixed at a mass ratio of 0.1:5.0;

[0046] Figure 24 The CDs and Ca5(PO4)3OH:Eu prepared in Example 6 of this invention 3+ / Tb 3+ CIE diagram of composite nanoparticles ground and mixed at a mass ratio of 0.1:5.6. Detailed Implementation

[0047] This invention provides a luminescent composite nanomaterial comprising luminescent nanomaterials and carbon quantum dots, solving the problems of complex preparation processes, high costs, low temperature sensitivity, and limited applications in existing technologies. Furthermore, this luminescent composite nanomaterial exhibits good stability and multiple anti-counterfeiting capabilities. The molecular formula of the luminescent nanomaterial is Ca5(PO4)3OH:Eu. 3+ Ca5(PO4)3OH:Tb 3+ Ca5(PO4)3OH:Eu 3+ / Tb 3+ .

[0048] In a first typical embodiment, the present invention provides a composite nanomaterial comprising luminescent nanomaterials and carbon quantum dots (CDs); the molecular formula of the luminescent nanomaterials is Ca5(PO4)3OH:x%Eu. 3+ / y%Tb 3+ Tb 3+ The doping concentration, i.e., y%, is 0%-90%, Eu 3+ The doping concentration, i.e., x% is 0%-90%; x and y cannot be 0 at the same time.

[0049] Tb 3+ The doping concentration can be 0%, 0.1%, 0.5%, 0.7%, 0.9%, 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, etc., preferably 0.1% to 90%.

[0050] Eu 3+ The doping concentration can be 0%, 0.1%, 0.5%, 0.7%, 0.9%, 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, etc., preferably 0.1% to 90%.

[0051] The luminescent nanomaterial is Ca5(PO4)3OH:Eu3+ At that time, in order to obtain better fluorescence effect, Eu 3+ The doping concentration is 60%~80%, preferably 60%~70%.

[0052] The luminescent nanomaterial is Ca5(PO4)3OH:Tb 3+ In order to obtain better fluorescence effect, Tb 3+ The doping concentration is 60%~80%, preferably 60%~70%.

[0053] The luminescent nanomaterial is Ca5(PO4)3OH:Eu 3+ / Tb 3+ At that time, Eu 3+ The doping concentration is 0.1% to 1%, preferably 0.1% to 0.7%, more preferably 0.5% to 0.7%, and even more preferably 0.6% to 0.7%; Tb 3+ The doping concentration is 60%-80%, preferably 60%~70%.

[0054] Carbon quantum dots and luminescent nanomaterials Ca5(PO4)3OH:Eu 3+ / Tb 3+ The mass ratio is 0.1:(1~50). Depending on the application, the mass ratio can be further adjusted.

[0055] Furthermore, when the terbium doping concentration is 0%, the molecular formula of the luminescent nanomaterial is Ca5(PO4)3OH:Eu. 3+ It exhibits a red emission peak at an excitation wavelength of 395 nm. Specifically, the emission peaks are at 590 nm and 615 nm, and the emission color is red.

[0056] Furthermore, when the europium doping concentration is 0%, the molecular formula of the luminescent nanomaterial is Ca5(PO4)3OH:Tb. 3+ At an excitation wavelength of 371 nm, the emission peaks are at 490 nm and 545 nm, with emission colors of green and red. Under these conditions, the presence of green and red emission peaks, coupled with the absence of red light when doped with terbium but not europium, indicates that europium doping is necessary for red light emission.

[0057] Furthermore, the molecular formula of the luminescent nanomaterial is Ca5(PO4)3OH:Eu 3+ / Tb 3+ It exhibits red and green emission peaks at an excitation wavelength of 371 nm.

[0058] Furthermore, carbon quantum dots exhibit a blue light emission peak at an excitation wavelength of 371 nm.

[0059] Furthermore, the luminescent composite nanomaterial, a mixture of europium-terbium co-doped calcium phosphate and carbon quantum dots in a specific ratio, exhibits blue, green, and red emission peaks at an excitation wavelength of 371 nm.

[0060] In a second typical embodiment, the present invention provides a method for preparing the above-mentioned composite nanomaterials, comprising:

[0061] Luminescent nanomaterials Ca5(PO4)3OH:x%Eu were prepared separately. 3+ / y%Tb 3+ Carbon quantum dots (CDs) are mixed together to obtain the product.

[0062] Luminescent nanomaterial Ca5(PO4)3OH:x%Eu 3+ / y%Tb 3+ The preparation method includes the following steps: terbium salt, europium salt, calcium salt and solvent are mixed, and then mixed with Na2HPO4 solution. The pH is adjusted to alkaline, and a hydrothermal reaction is carried out. After centrifugation, washing and drying, the product is obtained.

[0063] The preparation method specifically includes the following steps: terbium salt, europium salt, calcium salt and solvent are mixed to obtain a mixed solution, Na2HPO4 solution is added dropwise to the mixed solution under vigorous stirring, the pH is adjusted to alkaline, and then a hydrothermal synthesis reaction is carried out. After centrifugation, washing and drying, the product is obtained.

[0064] Vigorous stirring conditions can be 1000 r / min-1300 r / min.

[0065] Furthermore, the pH is adjusted to 8-10, preferably 9.0-9.5, and most preferably 9.3. Maintaining a suitable pH value is crucial for the formation of calcium phosphate; low pH prevents formation, while high pH may affect morphology and luminescence.

[0066] Furthermore, terbium salts include Tb(NO3)3, europium salts include EuCl3, and calcium salts include CaCl2.

[0067] Furthermore, the solvent is water, the reaction temperature is 50~70℃, and the reaction time is 0.5~2h. Excessive temperature may affect the morphology.

[0068] In the Na2HPO4 solution, the mass-to-volume ratio of Na2HPO4 to water is (0.1~0.5g):(10~30mL), preferably (0.3~0.4g):(15~25mL).

[0069] Furthermore, the pH is adjusted using an alkali, wherein the alkali includes a sodium hydroxide solution with a concentration of 0.5~2 mol / L, preferably 1 mol / L.

[0070] The mass-volume ratio of calcium salt to solvent is (0.01~1g):(30~50mL), preferably (0.01~0.1g):(35~45mL).

[0071] The mass ratio of calcium salt to Na2HPO4 is (0.01~1):(0.1~0.5), preferably (0.01~0.1):(0.3~0.4).

[0072] Furthermore, the Ca5(PO4)3OH:Eu 3+ In the mixture, the molar ratio of europium salt to calcium salt is (0.1~0.9):(0.1~0.9), preferably (0.6~0.8):(0.2~0.4), and most preferably 0.7:0.3; the Ca5(PO4)3OH:Tb 3+ In the mixture, the molar ratio of terbium salt to calcium salt is (0.1~0.9):(0.1~0.9), preferably (0.6~0.8):(0.2~0.4), and most preferably 0.7:0.3; the Ca5(PO4)3OH:Eu 3+ / Tb 3+ In this process, the molar ratio of terbium salt, europium salt, and calcium salt is 70:(0.1~1):(29~29.9), preferably 70:(0.5~0.7):(29.3~29.5), and most preferably 70:0.7:29.3.

[0073] Furthermore, the preparation method of the carbon quantum dots includes the following steps: mixing citric acid, ethanolamine, and water, stirring until the solution is clear, and then carrying out a hydrothermal reaction. Specifically, the preparation method includes: adding ethanolamine dropwise to an aqueous solution containing citric acid, stirring vigorously until clear, carrying out a hydrothermal synthesis reaction at 170-200℃ for 5-8 hours, and purifying to obtain the final product.

[0074] Vigorous stirring conditions can be 1000 r / min-1300 r / min.

[0075] The present invention further includes centrifugation, washing, drying, and grinding to obtain a solid product after the reaction of calcium chloride, terbium nitrate, europium chloride, and disodium hydrogen phosphate. The present invention does not impose special restrictions on the specific steps of centrifugation, washing, drying, and grinding, and methods commonly used by those skilled in the art can be used.

[0076] In a third typical embodiment, the present invention provides the application of the above-mentioned composite nanomaterials in white LEDs, anti-counterfeiting and / or temperature sensing.

[0077] In a fourth typical embodiment, the present invention provides a white luminescent composite nanomaterial, wherein the material is the aforementioned composite nanomaterial. The composite nanomaterial includes luminescent nanomaterials and carbon quantum dots (CDs); the luminescent nanomaterial is Ca5(PO4)3OH:Eu 3+ / Tb 3+ .

[0078] The excitation wavelength is 365~375nm, preferably 370~375nm, and most preferably 371nm; the power is 1~10W, preferably 2~6W, and most preferably 4W.

[0079] Among them, the luminescent nanomaterial Ca5(PO4)3OH:Eu 3+ / Tb 3+ The doping concentrations of terbium and europium in the carbon quantum dots and luminescent nanomaterials Ca5(PO4)3OH:Eu 3+ / Tb 3+ The mass ratio is crucial. Luminescent nanomaterial Ca5(PO4)3OH:Eu 3+ / Tb 3+ In this process, when the terbium doping concentration is 60%~80% (preferably 65%~75%, more preferably 68%~72%), the europium doping concentration must be 0.5%~0.7%. If the europium doping concentration is 0.1% and 0.3%, the emission intensity of the green light portion is stronger than that of the red light portion, therefore white light cannot be obtained by mixing them in any proportion. Furthermore, under the aforementioned limitations on the terbium and europium doping concentrations, carbon quantum dots and the luminescent nanomaterial Ca5(PO4)3OH:Eu 3+ / Tb 3+ The mass ratio is 0.1:(4~6), preferably 0.1:(5~6), more preferably 0.1:(5.5~5.7), and most preferably 0.1:5.6 to obtain a material that emits white light, which is cold white light. According to the exploration in Example 6, white light can only be obtained at 0.1:5.6, while 0.1:6.0 and 0.1:5.0 do not produce white light.

[0080] In a fifth typical embodiment, the present invention provides a white LED comprising the above-mentioned white luminescent composite nanomaterial or the above-mentioned composite nanomaterial composed of luminescent nanomaterial and carbon quantum dots (CDs); wherein the luminescent nanomaterial is Ca5(PO4)3OH:Eu 3+ / Tb 3+ .

[0081] The white light luminescent composite nanomaterial of the present invention can emit white light under 371nm laser excitation, and the luminescence intensity is high.

[0082] In a sixth typical embodiment, the present invention provides a temperature sensor comprising the aforementioned composite nanomaterials: carbon quantum dots (CDs) and luminescent nanomaterials Ca5(PO4)3OH:Eu. 3+ / Tb 3+ As well as carbon quantum dots (CDs) and luminescent nanomaterials Ca5(PO4)3OH:Eu 3+ / Tb 3+ The resulting composite nanomaterials all exhibit temperature-sensing properties, with fluorescence emission intensity decreasing as temperature increases. The excitation wavelength is 365-375 nm, preferably 370-375 nm, and most preferably 371 nm, or 590-620 nm; the power is 1-10 W, preferably 2-6 W, and most preferably 4 W. The temperature is 25-300℃.

[0083] In this invention, the luminescent nanomaterial Ca5(PO4)3OH:Eu mainly plays a temperature sensing role. 3+ / Tb 3+ Therefore, carbon quantum dots and luminescent nanomaterials Ca5(PO4)3OH:Eu in composite nanomaterials 3+ / Tb 3+ The mass ratio can be further limited to 0.1:(10~40), or it can be left unrestricted.

[0084] The luminescent composite nanomaterials prepared by this invention can emit fluorescence of different colors under excitation light of different wavelengths (395nm, 371nm), thereby achieving multiple anti-counterfeiting functions. Under 371nm excitation, the composite nanoparticles prepared in Example 5 are heated (30-300℃), and the fluorescence intensity of the material decreases as the temperature increases, thus enabling temperature measurement.

[0085] In a seventh typical embodiment, the present invention provides an anti-counterfeiting material, the anti-counterfeiting material comprising the above-mentioned carbon quantum dots (CDs) and the above-mentioned luminescent nanomaterial Ca5(PO4)3OH:x%Eu 3+ / y%Tb 3+ And the aforementioned composite nanomaterials.

[0086] When applied to anti-counterfeiting materials, in order to better achieve multiple anti-counterfeiting effects, carbon quantum dots and luminescent nanomaterials Ca5(PO4)3OH:Eu 3+ / Tb 3+ The mass ratio is 0.1:(10~40), preferably 0.1:(10~20), and even more preferably 0.1:(14~16). The specific ratio can also be adjusted according to the desired anti-counterfeiting effect.

[0087] To achieve multiple anti-counterfeiting effects, the above-mentioned combination of carbon quantum dots and luminescent nanomaterial Ca5(PO4)3OH:Eu is preferred. 3+ / Tb 3+ The composite nanomaterial is used as the functional component of the anti-counterfeiting material. The anti-counterfeiting material comprises the functional component (such as the composite nanomaterial described above), polyvinyl alcohol, and water. The specific preparation method includes: mixing the functional component (such as the composite nanomaterial described above), polyvinyl alcohol, and water; coating the mixture onto the surface of the anti-counterfeiting material; and drying. The ratio of polyvinyl alcohol, water, and the functional component (such as the composite nanomaterial described above) is (0.05~0.15g):(1~5mL):(0.1~0.2g), preferably (0.08~0.12g):(2.5~3.5mL):(0.12~0.18g).

[0088] Ca5(PO4)3OH:Eu 3+ It emits red light at an excitation wavelength of 390~400nm (preferably 395nm).

[0089] Ca5(PO4)3OH:Tb 3+ It emits green and red light at an excitation wavelength of 365~375nm (preferably 370~375nm, most preferably 371nm).

[0090] Ca5(PO4)3OH:Eu 3+ / Tb 3+ It emits red and green light at an excitation wavelength of 365~375nm (preferably 370~375nm, most preferably 371nm).

[0091] The carbon dots emit blue light at an excitation wavelength of 365~375nm (preferably 370~375nm, most preferably 371nm).

[0092] Preferably, it is composed of luminescent nanomaterials Ca5(PO4)3OH:Eu 3+ / Tb 3+ The composite nanomaterial obtained by mixing with carbon quantum dots (CDs) can be used as an anti-counterfeiting material. When excited at a wavelength of 365~375nm (preferably 370~375nm, most preferably 371nm), it emits red, green and blue light, which can achieve multiple anti-counterfeiting measures.

[0093] The luminescent nanomaterial Ca5(PO4)3OH:Eu provided by this invention 3+ It emits red light at an excitation wavelength of 395 nm. (Ca5(PO4)3OH:Tb) 3+ It emits green and red light at an excitation wavelength of 371 nm. (Ca5(PO4)3OH:Eu) 3+ / Tb 3+The carbon dots emit red and green light under a 371 nm excitation wavelength, while the carbon dots emit blue light under the same excitation wavelength. The carbon dots mixed with Ca5(PO4)3OH:Eu... 3+ / Tb 3+ Composite nanomaterials emit red, green, and blue light at an excitation wavelength of 371 nm, enabling multiple anti-counterfeiting measures.

[0094] In this invention, unless otherwise specified, all other test materials and instruments are conventional test materials in the field and can be purchased through commercial channels.

[0095] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0096] Example 1

[0097] This embodiment provides Ca5(PO4)3OH:70%Eu 3+ The preparation of [the substance] includes the following steps:

[0098] (1) Weigh 0.0441g of calcium chloride and 0.3847g of europium chloride into a beaker, add 40mL of water and stir until the solution is clear.

[0099] (2) Weigh 0.3223g of Na2HPO4 and add it to a beaker, then add 20mL of water.

[0100] (3) While stirring vigorously, add the solution in (2) dropwise into the solution in (1) and adjust the pH to 9.3 with 1 mol / L sodium hydroxide solution.

[0101] (4) Transfer the solution from (3) into a hydrothermal reactor and react at 60°C for 1 hour. Then centrifuge the reaction solution at 13000 r / min for 15 min, wash with water, dry, and grind to obtain Ca5(PO4)3OH:70%Eu 3+ Nanoparticles.

[0102] The Ca5(PO4)3OH:70%Eu obtained by determination 3+ Scanning electron microscope images of nanoparticles, such as Figure 1 As shown. From Figure 1 As can be seen from this, Ca5(PO4)3OH:70%Eu 3+ It is in the form of short rods. Ca5(PO4)3OH:70%Eu 3+ The XRD pattern of the nanoparticles is consistent with the standard card (PDF#86-0740), as shown below. Figure 2 As shown, the prepared Ca5(PO4)3OH:70%Eu 3+ Nanoparticles are a pure phase.

[0103] Figure 4 The Ca5(PO4)3OH:70%Eu prepared in this embodiment 3+ The excitation spectrum of nanoparticles shows that when the monitoring wavelength is 590 nm, the optimal excitation wavelength is around 395 nm.

[0104] Figure 5 Ca5(PO4)3OH:Eu prepared with different doping concentrations in this embodiment 3+ The emission spectrum of the nanoparticles was obtained with an excitation wavelength of 395 nm and a power of 4 W. The main emission peaks were around 590 nm and 615 nm.

[0105] Figure 6 The Ca5(PO4)3OH:70%Eu prepared in this embodiment 3+ The emission spectrum of the nanoparticles was obtained with an excitation wavelength of 371 nm and a power of 4 W. The main emission peaks were around 590 nm and 615 nm.

[0106] Figure 7 The fluorescence intensity changes at 590 nm of Ca5(PO4)3OH nanoparticles with different europium doping concentrations were prepared for this embodiment. It was found that the luminescence was strongest when the europium doping concentration was 70%, and there was no green light emission when the terbium doping concentration was 0%.

[0107] Example 2

[0108] This embodiment provides Ca5(PO4)3OH:70%Tb 3+ The preparation of [the substance] includes the following steps:

[0109] (1) Weigh 0.0441g of calcium chloride and 0.4756g of terbium nitrate into a beaker, add 40mL of water and stir until the solution is clear.

[0110] (2) Weigh 0.3223g of Na2HPO4 and add it to a beaker, then add 20mL of water.

[0111] (3) While stirring vigorously, add the solution in (2) dropwise into the solution in (1) and adjust the pH to 9.3 with 1 mol / L sodium hydroxide solution.

[0112] (4) Transfer the solution from (3) into a hydrothermal reactor and react at 60°C for 1 hour. Then centrifuge the reaction solution at 13000 r / min for 15 min, wash with water, dry, and grind to obtain Ca5(PO4)3OH:70%Tb. 3+ Nanoparticles.

[0113] Figure 8 The Ca5(PO4)3OH:70%Tb prepared in this embodiment 3+The excitation spectrum of nanoparticles shows that when the monitoring wavelength is 550 nm, the optimal excitation wavelength is around 371 nm.

[0114] Figure 9 Ca5(PO4)3OH:Tb with different doping concentrations were prepared for this embodiment. 3+ The emission spectrum of the nanoparticles was obtained with an excitation wavelength of 371 nm and a power of 4 W. The main emission peaks were around 490 nm, 545 nm, 587 nm, and 621 nm. The fluorescence intensity at 587 nm and 621 nm was low. The nanoparticles were doped with terbium but not europium and emitted almost no red light, indicating that europium doping is necessary to produce red light.

[0115] Figure 10 The fluorescence intensity changes at 545 nm of Ca5(PO4)3OH nanoparticles with different terbium doping concentrations were prepared for this embodiment. It was found that the luminescence was strongest when the terbium doping concentration was 70%. Therefore, the terbium doping concentration was set to 70% when preparing europium-terbium co-doped calcium phosphate nanoparticles.

[0116] Example 3

[0117] This example provides Ca5(PO4)3OH:0.7%Eu 3+ / 70%Tb 3+ The preparation of [the substance] includes the following steps:

[0118] (1) Weigh 0.0646g CaCl2, 1.05 mL 0.01 mol / L EuCl3, 0.4756g Tb(NO3)3, and 40 mL water, and stir until the solution is clear.

[0119] (2) Weigh 0.3223g of Na2HPO4 and add it to a beaker, then add 20ml of water.

[0120] (3) Under vigorous stirring (1000 r / min-1300 r / min), the solution in (2) is added dropwise to the solution in (1), and the pH is adjusted to 9.3 with 1 mol / L sodium hydroxide solution.

[0121] (4) Transfer the solution from (3) into a hydrothermal reactor and react at 60°C for 1 hour. Then centrifuge the reaction solution at 13000 r / min for 15 min, wash with water, dry, and grind to obtain Ca5(PO4)3OH:0.7%Eu 3+ / 70%Tb 3+ Nanoparticles, abbreviated as Ca5(PO4)3OH:Eu 3+ / Tb 3+ Nanoparticles.

[0122] Figure 11The Ca5(PO4)3OH:Eu prepared in this embodiment 3+ / Tb 3+ The excitation spectrum of nanoparticles shows that when the monitoring wavelength is 590 nm, the optimal excitation wavelength is around 371 nm.

[0123] Figure 12 The Ca5(PO4)3OH:Eu prepared in this embodiment 3+ / Tb 3+ The emission spectrum of the nanoparticles was obtained with an excitation wavelength of 371 nm and a power of 4 W. The main emission peaks were around 490 nm, 545 nm, 590 nm, and 615 nm.

[0124] Figure 13 The Ca5(PO4)3OH:Eu prepared in this embodiment 3+ / Tb 3+ The chromaticity diagram (CIE diagram) is located at coordinates (0.4522, 0.4097).

[0125] Figure 14 The Ca5(PO4)3OH:Eu prepared in this embodiment 3+ / Tb 3+ The emission spectrum of the nanoparticles was obtained with an excitation wavelength of 395 nm and a power of 4 W. The main emission peaks were around 490 nm, 590 nm, and 615 nm.

[0126] Example 4

[0127] The preparation of carbon quantum dots (CDs) includes the following steps:

[0128] (1) Weigh 19.212g of citric acid and add it to a beaker. Add 20mL of water and stir until homogeneous to obtain a citric acid (0.1 mol) aqueous solution. Then add 11.98mL of ethanolamine (0.2mol) aqueous solution to the citric acid aqueous solution and stir vigorously until the solution is clear.

[0129] (2) The above clear solution was sealed in a reaction vessel, heated to 180°C and kept for 6 hours, and then naturally cooled to room temperature to obtain a reddish-brown liquid.

[0130] (3) Rotary evaporation: The reddish-brown liquid obtained in step (2) is rotary evaporated, and then dialyzed for 3 days with a dialysis bag to remove unreacted ethanolamine precursors and small molecule products. The liquid is then freeze-dried to obtain carbon quantum dots.

[0131] Transmission electron microscopy (TEM) images of the carbon quantum dots (CDs) obtained in this embodiment are shown below. Figure 3 As shown in the figure, CDs are dot-like and approximately 3 nm in size.

[0132] Determining the emission spectrum of carbon quantum dots, such as Figure 15 As shown, when the wavelength of the excitation source used is 371nm and the power is 4W, its emission peak is near 453nm.

[0133] Figure 16 The figure shows the chromaticity diagram (CIE diagram) of carbon quantum dots. As can be seen from the figure, its coordinate position is (0.1477, 0.1371).

[0134] Example 5

[0135] This embodiment provides a method for preparing luminescent composite nanoparticles, the specific steps of which are as follows:

[0136] First, the CDs from Example 4 and the Ca5(PO4)3OH:Eu from Example 3 were combined. 3+ / Tb 3+ The two are mixed and ground at a mass ratio of 0.1:15.

[0137] Figure 17 The emission spectrum of the composite nanoparticles prepared in this embodiment is shown. The excitation wavelength is 371 nm and the power is 4 W. The main emission peaks are around 490 nm, 545 nm, 590 nm and 615 nm.

[0138] Example 6

[0139] This embodiment uses Ca5(PO4)3OH:x%Eu with different europium doping concentrations. 3+ / 70%Tb 3+ Mixed with carbon dots in different proportions. Using different proportions of Ca5(PO4)3OH:x%Eu 3+ / 70%Tb 3+ Mixing CDs at different quality ratios can produce CIE diagrams of different colors, but not necessarily white light; white light must be produced at the appropriate ratio.

[0140] When the europium doping concentration is 0.1% and 0.3%, the emission intensity of the green portion is stronger than that of the red portion, so white light cannot be obtained by mixing in any proportion; when the europium doping concentration is 0.5% and 0.7%, after mixing with CDs at different mass ratios, the final carbon quantum dots and Ca5(PO4)3OH:0.7%Eu 3+ / 70%Tb 3+ A white light-emitting composite nanomaterial was obtained by grinding and mixing the nanomaterials at a mass ratio of 0.1:5.6. The specific steps are as follows:

[0141] The CDs from Example 4 and the Ca5(PO4)3OH:0.7%Eu from Example 3 were mixed. 3+ / 70%Tb 3+The two materials were mixed and ground at a mass ratio of 0.1:(4~6). The ratio was adjusted according to the CIE diagram, and grinding continued until the composite nanomaterial emitted white light at an excitation wavelength of 371 nm (excitation power of 4 W). At this point, CDs and Ca5(PO4)3OH:Eu 3+ / Tb 3+ The mass ratio of nanoparticles is 0.1:5.6, thus obtaining a white luminescent composite nanomaterial.

[0142] The CDs and Ca5(PO4)3OH:0.7%Eu prepared in this embodiment are provided. 3+ / 70%Tb 3+ Nanoparticles were used in a mass ratio of 0.1:6.0 ( Figure 22 ), 0.1:5.6 ( Figure 24 ) and 0.1:5.0 ( Figure 23 The CIE plot of the ground and mixed composite nanomaterials under 371 nm wavelength excitation (excitation power 4 W) shows that CDs and Ca5(PO4)3OH:Eu 3+ / Tb 3+ When the nanoparticles are ground and mixed at a mass ratio of 0.1:5.6, their coordinate positions are (0.3125, 0.3253), which corresponds to cool white light. Furthermore, CDs and Ca5(PO4)3OH:Eu 3+ / Tb 3+ The composite nanomaterial, with nanoparticles ground and mixed at a mass ratio of 0.1:6.0, has coordinates (0.3362, 0.3401). CDs and Ca5(PO4)3OH:Eu 3+ / Tb 3+ The composite nanomaterial with nanoparticles ground and mixed at a mass ratio of 0.1:5.0 has coordinates (0.2989, 0.2689), which is not within the white light range.

[0143] Application Example 1

[0144] The material from Example 5 was used in a temperature sensing experiment, and the specific steps are as follows:

[0145] (1) Place the composite nanoparticles into a temperature measuring device;

[0146] (2) Heating was performed using a variable-temperature device, and the fluorescence spectrum of the composite nanoparticles was measured using a spectrometer under 371 nm laser irradiation. The fluorescence intensity curve of the red emission portion of europium ions from the europium-terbium co-doped calcium phosphate nanoparticles in the composite nanoparticles was obtained as a function of temperature. This curve can then be used to calculate the temperature of the environment in which the composite nanomaterials are located, such as... Figure 19 , Figure 20As shown, the excitation light source used was 371 nm with a power of 4 W, indicating that the fluorescence emission intensity of the composite nanoparticles decreased with increasing temperature. By observing the changes in fluorescence spectra, the color changes of the material at different temperatures can be correlated, thus providing the emission spectra of the overall material at different temperatures, such as room temperature, 100℃, 200℃, and 300℃. Figure 18 As shown.

[0147] (3) Under 371 nm excitation, temperature sensing can also originate from CDs or from Ca5(PO4)3OH:Eu 3+ / Tb 3+ Nanoparticles, but the emission at 590 and 615 nm can only originate from Ca5(PO4)3OH:Eu 3+ / Tb 3+ Nanoparticles, and the blue light emission of CDs does not include Ca5(PO4)3OH:Eu 3+ / Tb 3+ The nanoparticles emit a distinct red light, making them difficult to distinguish with the naked eye.

[0148] Application Example 2

[0149] The materials prepared in Examples 1-5 were used in anti-counterfeiting experiments, with an excitation power of 4W. The specific steps are as follows:

[0150] (1) Prepare four portions of 0.1g polyvinyl alcohol and add 3mL of water. After it becomes a gel, add 0.15g of Ca5(PO4)3OH:Eu to each portion. 3+ Ca5(PO4)3OH:Tb 3+ Ca5(PO4)3OH:Eu 3+ / Tb 3+ The powder of the luminescent composite nanoparticles prepared in Example 5 was stirred evenly; then 0.05g of carbon dots was prepared and stirred evenly.

[0151] (2) Prepare suitable cardstock, cover the starfish cutout pattern with five corners, coat with the ink obtained above, and dry to obtain the corresponding pattern.

[0152] Figure 21 The Ca5(PO4)3OH:Eu prepared in Example 1 of this invention 3+ Excitation at 395 nm, Ca5(PO4)3OH:Tb prepared in Example 2 3+ Example 3: Ca5(PO4)3OH:Eu 3+ / Tb 3+ Anti-counterfeiting images of CDs prepared in Example 4 and composite nanoparticles prepared in Example 5 excited at 371 nm. During coating, Ca5(PO4)3OH:Eu was selected as the top corner for coating. 3+Luminescent composite nanomaterial ink (corresponding to) Figure 21 (a) marked in the text), clockwise, are the luminescent composite nanoparticle inks prepared in Example 5 (corresponding to...) Figure 21 (b) marked angle), Ca5(PO4)3OH:Eu prepared in Example 3 3+ / Tb 3+ Luminescent composite nanomaterial ink (corresponding to) Figure 21 (c) marked angle), Ca5(PO4)3OH:Tb prepared in Example 2 3+ Luminescent composite nanomaterial ink (corresponding to) Figure 21 (d) marks the angle), and the CDs ink prepared in Example 4 (corresponding to) Figure 21 (the corner marked with (e) in the text).

[0153] Application Example 3

[0154] The specific steps for LED lighting experiments are as follows:

[0155] The CDs prepared in Example 4 and the Ca5(PO4)3OH:0.7%Eu prepared in Example 3 were compared. 3+ / 70%Tb 3+ Nanoparticles were ground and mixed at a mass ratio of 0.1:5.6 to obtain white luminescent composite nanomaterials.

[0156] like Figure 24 As shown, the excitation light source used is 371nm and the power is 4W.

[0157] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. The application of composite nanomaterials in white LEDs, anti-counterfeiting and / or temperature sensing, characterized in that, The composite nanomaterials include luminescent nanomaterials and carbon quantum dots. The molecular formula of the luminescent nanomaterial is Ca5(PO4)3OH:x%Eu 3+ / y%Tb 3+ Where y% is 0%~90%, x% is 0%~90%, and x and y cannot be 0 at the same time; The luminescent nanomaterial is Ca5(PO4)3OH:Eu 3+ / Tb 3+ At that time, Eu 3+ The doping concentration is 0.5%~0.7%; Tb 3+ The doping concentration is 60%~80%; In white LED applications, the mass ratio of carbon quantum dots to luminescent nanomaterials is 0.1:5.6; the carbon quantum dots and luminescent nanomaterials are Ca5(PO4)3OH:Eu 3+ / Tb 3+ The composite nanomaterials emitted white light when excited by a 371nm laser. In anti-counterfeiting and / or temperature sensing applications, the mass ratio of carbon quantum dots to luminescent nanomaterials is 0.1:(10~40); The fluorescence emission intensity of the composite nanomaterial decreases with increasing temperature; the temperature is 30~300℃.

2. The application according to claim 1, characterized in that, The preparation method of the composite nanomaterial includes: preparing the luminescent nanomaterial Ca5(PO4)3OH:x%Eu 3+ / y%Tb 3+ It is obtained by mixing with carbon quantum dots.

3. The application according to claim 2, characterized in that, Luminescent nanomaterial Ca5(PO4)3OH:x%Eu 3+ / y%Tb 3+ The preparation method includes the following steps: terbium salt, europium salt, calcium salt and solvent are mixed, then mixed with Na2HPO4 solution, the pH is adjusted to alkaline, and hydrothermal reaction is carried out to obtain the product; Terbium salts include Tb(NO3)3, europium salts include EuCl3, and calcium salts include CaCl2; the solvent includes water, the hydrothermal reaction temperature is 50~70℃, and the hydrothermal reaction time is 0.5~2h; In the Na2HPO4 solution, the mass-volume ratio of Na2HPO4 to water is (0.1~0.5g):(10~30mL); the mass-volume ratio of calcium salt to solvent is (0.01~1g):(30~50mL); and the mass ratio of calcium salt to Na2HPO4 is (0.01~1):(0.1~0.5). Ca5(PO4)3OH:Eu 3+ In this mixture, the molar ratio of europium salt to calcium salt is (0.1~0.9):(0.1~0.9); Ca5(PO4)3OH:Tb 3+ In this mixture, the molar ratio of terbium salt to calcium salt is (0.1~0.9):(0.1~0.9); Ca5(PO4)3OH:Eu 3+ / Tb 3+ In this mixture, the molar ratio of terbium salt, europium salt, and calcium salt is 70:(0.1~1):(29~29.9).

4. A white luminescent composite nanomaterial, characterized in that, The white luminescent composite nanomaterial is the composite nanomaterial used in any one of claims 1 to 3, and the white light is cold white light.

5. A white LED, characterized in that, Includes the composite nanomaterials in any one of the applications described in claims 1 to 3 or the white luminescent composite nanomaterials described in claim 4.

6. A temperature sensor, characterized in that, The temperature sensor comprises the composite nanomaterials used in any one of claims 1 to 3.

7. An anti-counterfeiting material, characterized in that, The anti-counterfeiting material includes the composite nanomaterials described in any one of claims 1 to 3.

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