Novel Cr3+Near-infrared fluorescent powder doped with fluorideAnd method for preparing the same
Technical Field
The invention relates to fluorescent powder applied to the field of luminescence, in particular to a near-infrared luminescent material converted from the fluorescent powder and application thereof in the fields of night vision goggles, biomedicine and food detection.
Background
In recent years, the human society is continuously developing forward, the added value brought by science and technology is far higher than the existing cognition of people, high attention is paid to various countries, the investment of various countries on science and technology is increased day by day, and the rapid development of science and technology is promoted. Meanwhile, with the continuous efforts of scientists, the near infrared technology has been widely applied to various fields such as military affairs, agriculture, food safety, security monitoring, biomedicine, face recognition, unmanned driving and the like. At present, the common near-infrared light sources on the market mainly comprise halogen tungsten lamps, infrared lasers, near-infrared LEDs and the like, however, the common near-infrared light sources have inherent defects: the halogen tungsten lamp has the defects of short service life, slow response, large volume, high energy consumption, low efficiency and the like; the infrared laser has a narrow emission band (< 10 nm) and high cost; however, the infrared light emitting diode has a narrow emission peak (< 50 nm), the emission peak changes, the luminous intensity is seriously reduced at high temperature, and the infrared light emitting diode cannot be widely applied to the near infrared technology.
Since the invention of a blue light chip, a fluorescent powder converted white light LED (pc-LED) is rapidly developed, and at present, the blue light LED is mature in structure and low in production cost, and the like, and the blue light LED is adopted to excite the near-infrared fluorescent powder to construct a near-infrared light source by virtue of the mature structure of the pc-LED, so that a new way for generating near-infrared light is formed. The novel near-infrared light source prepared by the scheme of the blue light LED and the near-infrared fluorescent material has the advantages of low cost, wide and adjustable spectrum, high thermal stability, high power, energy conservation, environmental protection, mature structure, miniaturization, quick response and the like, and becomes the most effective way for solving the problem of lacking of miniaturization, quick response and broadband near-infrared light sources.
In recent years, Cr3+Becomes the main stream of near-infrared luminous ions, and adjusts Cr because the 3d orbit of the near-infrared luminous ions is greatly influenced by a crystal field3+The crystal field environment can effectively adjust the width of the emission peak.Cr3+The doped oxide and other materials show better near-infrared luminescence performance and present potential application prospects. Wherein, M, Erdem, etc. (M, Erdem)J. Am. Ceram. Soc.2020, 103, 5111-3+Doped in Y3Al5O12The luminescent property in the material can be effectively excited by blue light, the emission peak is about 700 nm, and the material can be used as a near infrared light material. However, the fluorescent powder generally has the defects of narrow emission peak, quantum efficiency and the like, so that the comprehensive performance of the near-infrared light source is greatly reduced, and further the commercial application of the fluorescent powder is limited. And Cr3+Ion doping in fluoride can produce a wider emission peak and higher quantum efficiency (Chem. Eng. J.2021, DOI: 10.1016/j.cej.2021.129271.). Based on the above, a novel near-infrared fluorescent powder is developed, and the fluorescent powder has important guiding significance for the development of the near-infrared light-emitting field.
This patent discloses a novel unreported Cr3+The fluoride-doped garnet-structured broadband near-infrared fluorescent powder has the advantages of wider emission peak wavelength, excellent thermal stability, high luminous efficiency and the like, and is expected to solve the problem of Cr3+Doped oxide has the defects of low emission peak, narrow quantum efficiency and the like, and is expected to solve the technical bottleneck of lacking of miniaturization, quick response and broadband near-infrared light sources.
Disclosure of Invention
The invention provides a novel Cr capable of being effectively excited by blue light and ultraviolet light3+The fluoride-doped near-infrared fluorescent powder and the preparation method thereof have the advantages that the preparation raw materials are easy to obtain, the process is simple, and the industrial production is easy to realize; the obtained near-infrared fluorescent powder has the advantages of regular shape, wide half-peak width, high luminous efficiency and excellent thermal stability.
The novel Cr3+The doped fluoride near-infrared fluorescent powder has the following chemical formula: a. the a3-B x3-C2F12:xCr3 +,aRE3+Wherein A is one or the combination of more of Li, Na, K, Ru, Cs and the like; b is one or the combination of more of Li, Na, K, Ru, Cs and the like; c isGa. One or more of Al, In, Sc, Lu, La and the like; RE is one or a combination of Yb, Nd, Ce, Er and Pr.
The novel Cr3+The near infrared fluorescent powder doped with fluoride is characterized in that the anions in the fluorescent powder are all F elements.
The novel Cr3+The near-infrared fluorescent powder doped with fluoride is characterized by 0<x<2, 0≤a≤0.2。
The novel Cr3+The doped fluoride near infrared fluorescent powder is characterized in that raw materials containing A, B, C are oxides or fluorides or nitrates or carbonates corresponding to all elements.
The novel Cr3+The doped fluoride near-infrared fluorescent powder is characterized in that the adding sequence is that the raw material containing C is added firstly, and then the doped Cr is added3+Ionic feed stock and finally A, B containing feed stock. The novel fluoride garnet structure broadband near-infrared fluorescent powder is characterized in that a solvent used for synthesis is a combination of hydrofluoric acid and water.
The novel Cr3+The near infrared fluorescent powder doped with fluoride is characterized in that a reaction device used in synthesis is polytetrafluoroethylene and a reaction kettle.
The novel Cr3+The near infrared fluorescent powder doped with fluoride is characterized in that a reagent used in the washing process is a combination of weak acid, pure water and absolute ethyl alcohol.
The invention also provides the novel Cr3+The preparation method of the doped fluoride near-infrared fluorescent powder adopts a hydrothermal synthesis method and comprises the following specific steps:
(a) according to the formula A a3-B3C x2-F12:xCr3+,aRE3+Weighing A, B, C, RE-containing fluoride or oxide according to stoichiometric ratio, drying, and sieving;
(b) measuring a certain amount of solvent, adding the solvent into a container at one time, putting a magnetic stirrer, and fixing a test tube on the magnetic stirrer;
(c) sequentially adding the dried raw materials in the step (a) into a container, and fully stirring for a period of time;
(d) putting the container in the step (c) into a closed protection device, transferring the container to a heating furnace, preserving the heat for a period of time at a certain temperature, and then cooling the container to room temperature along with the furnace;
(e) washing the reaction product obtained in the step (d) with a solvent for several times, centrifuging, and drying in a drying oven;
(f) grinding and sieving the product dried in the step (e) to obtain novel Cr3+Doped fluoride near-infrared fluorescent powder.
The novel Cr of the invention3+The doped fluoride near-infrared fluorescent powder and the preparation method thereof also comprise the following preferred scheme: preferably, in step (b), the solvent used is a combination of hydrofluoric acid and water; the mass fraction of the hydrofluoric acid is 40%, and the ratio of the hydrofluoric acid to the water is 1: 1-1: 3.
Preferably, in step (c), the vessel used is polytetrafluoroethylene and the stirring time is 2 to 5 hours.
Preferably, in the step (d), the used closed protection device is a reaction kettle, the heating rate of the heating furnace is 3-10 ℃/min, the heat preservation temperature is 80-220 ℃, and the heat preservation time is 2-20 h.
Preferably, in step (e), the washing agent is a combination of solvents such as pure water, absolute ethanol, weak acid, etc., and the number of washing times is 2-6
Preferably, in step (e), the rotation speed of the centrifuge is controlled at 2000-.
The novel Cr3+The preparation method of the near-infrared fluorescent powder doped with fluoride is characterized in that the obtained novel Cr3+The near-infrared fluorescent powder doped with fluoride has an emission peak of 650-1000 nm under the excitation of 440 nm, a half-peak width of 100-140 nm, an internal quantum efficiency of 50-90%, and a luminous intensity of the fluorescent powder maintained above 60% of a room temperature at 473K, and can be widely applied to the fields of biomedicine, food detection, security monitoring and the like.
In conclusion, compared with the prior art, the method has the beneficial effects that:
(1) the fluorescent powder provided by the invention has the advantages of larger composition selection and adjustment scope, regular appearance, high quantum efficiency and high thermal stability.
(2) The fluorescent powder has a wider excitation range and has the strongest excitation peak around 440, so the fluorescent powder is very suitable for excitation of a blue LED.
(3) The method for manufacturing the fluorescent powder is feasible, simple in production flow and convenient for large-scale production.
(4) The fluorescent powder can realize near-infrared emission with a wide band (the half-peak width is 100-200 nm), high efficiency (the internal quantum efficiency is 50-90%) and high thermal stability (the luminous intensity of the fluorescent powder is kept more than 60% of the room temperature at 473K) under the excitation of blue light.
Drawings
FIG. 1 shows novel Cr3+Excitation spectrum of the doped fluoride near-infrared fluorescent powder.
FIG. 2 shows novel Cr3+Emission spectrum of the doped fluoride near-infrared fluorescent powder.
FIG. 3 shows novel Cr3+And (3) a morphology graph of the doped fluoride near-infrared fluorescent powder.
FIG. 4 shows novel Cr3+And (3) a morphology graph of the doped fluoride near-infrared fluorescent powder.
FIG. 5 shows Cr3+And the emission spectrum of the rare earth doped broadband near-infrared fluorescent powder.
FIG. 6 shows Cr3+And the emission spectrum of the rare earth doped broadband near-infrared fluorescent powder.
Detailed description of the preferred embodiments
Embodiment 1
Novel Cr3+The near infrared fluorescent powder doped with fluoride is made of solid powder and has the molecular formula of Li3Na3Al0.95F12:0.05Cr3+. The preparation method comprises the following steps:
(1) weighing according to stoichiometric ratioAl2O3:0.204g,Cr(NO3)3·9H2O: 0.048g, LiF: 0.1556g, NaF: 0.2519 g. The raw materials are sequentially added into a polytetrafluoroethylene container and fully stirred for 3 hours.
(2) Putting the polytetrafluoroethylene container into a reaction kettle, putting the reaction kettle into a heating furnace for heating, heating to 180 ℃ at the heating rate of 5 ℃/min, preserving heat for 12 hours, and then cooling to room temperature along with the furnace;
(3) washing the product obtained in the step (2) with acetic acid, pure water and absolute ethyl alcohol twice respectively, centrifuging in a centrifuge with the rotating speed of 3000r/min, drying at 90 ℃, and sieving to obtain novel Cr3+Doped fluoride near-infrared fluorescent powder.
The near-infrared fluorescent powder obtained in the embodiment is excited under 460 nm blue light and a fluorescence spectrum is tested, and the result shows that the emission peak of the obtained fluorescent powder is between 650 and 900 nm, and the half-peak width is 105 nm.
Embodiment 2
Novel Cr3+The near infrared fluorescent powder doped with fluoride is made of solid powder and has the molecular formula of Li3Na3Ga0.95F12:0.05Cr3+. The preparation method comprises the following steps:
(1) weighing Ga according to stoichiometric ratio2O3:0.3749g,Cr(NO3)3·9H2O: 0.048g, LiF: 0.2490g, NaF: 0.2519 g. The raw materials are sequentially added into a polytetrafluoroethylene container and fully stirred for 2 hours.
(2) Putting the polytetrafluoroethylene container into a reaction kettle, putting the reaction kettle into a heating furnace for heating, heating to 150 ℃ at the heating rate of 3 ℃/min, preserving heat for 6 hours, and then cooling to room temperature along with the furnace;
(3) washing the product obtained in the step (2) with acetic acid, pure water and absolute ethyl alcohol twice respectively, centrifuging in a centrifuge with the rotating speed of 3000r/min, drying at 80 ℃, and sieving to obtain the novel Cr3+Doped fluoride near-infrared fluorescent powder.
The near-infrared fluorescent powder obtained in the embodiment is excited under 460 nm blue light and a fluorescence spectrum is tested, and the result shows that the emission peak of the obtained fluorescent powder is between 650 and 900 nm, and the half-peak width is 100 nm.
Embodiment 3
Novel Cr3+The near infrared fluorescent powder doped with fluoride is made of solid powder and has the molecular formula of Li3Na3Ga0.975In0.975F12:0.05Cr3+. The preparation method comprises the following steps:
(1) weighing Ga according to stoichiometric ratio2O3:0.1874g,In2O3:0.2776g,Cr(NO3)3·9H2O: 0.048g, LiF: 0.1556g, NaF: 0.4199 g. The raw materials are sequentially added into a polytetrafluoroethylene container and fully stirred for 4 hours.
(2) Putting the polytetrafluoroethylene container into a reaction kettle, putting the reaction kettle into a heating furnace for heating, heating to 220 ℃ at a heating rate of 3.5 ℃/min, preserving heat for 15 h, and then cooling to room temperature along with the furnace;
(3) washing the product obtained in the step (2) with acetic acid, pure water and absolute ethyl alcohol twice respectively, centrifuging in a centrifuge with the rotating speed of 3600r/min, drying at 80 ℃, and sieving to obtain the novel Cr3+Doped fluoride near-infrared fluorescent powder.
The near-infrared fluorescent powder obtained in the embodiment is excited under 460 nm blue light and a fluorescence spectrum is tested, and the result shows that the emission peak of the obtained fluorescent powder is between 650 and 900 nm, and the half-peak width is 110 nm.
Embodiment 4
Novel Cr3+The near infrared fluorescent powder doped with fluoride is made of solid powder and has the molecular formula of Li3Na3Al0.6Ga0.6In0.6F12:0.02Cr3+. The preparation method comprises the following steps:
(1) weighing Al according to stoichiometric ratio2O3:0.0956g,Ga2O3:0.1274g,In2O3:0.1895g,Cr(NO3)3·9H2O: 0.192g, LiF: 0.2556g, NaF: 0.3582 g. Sequentially adding the raw materials into polytetrafluoroethyleneThe vessel was stirred well for 4 h.
(2) Putting the polytetrafluoroethylene container into a reaction kettle, putting the reaction kettle into a heating furnace for heating, heating to 200 ℃ at the heating rate of 2.5 ℃/min, preserving the heat for 10 hours, and then cooling to room temperature along with the furnace;
(3) washing the product obtained in the step (2) with acetic acid, pure water and absolute ethyl alcohol twice respectively, centrifuging in a centrifuge with the rotating speed of 3400r/min, drying at 80 ℃, and sieving to obtain the novel Cr3+Doped fluoride near-infrared fluorescent powder.
The near-infrared fluorescent powder obtained in the embodiment is excited under 460 nm blue light and a fluorescence spectrum is tested, and the result shows that the emission peak of the obtained fluorescent powder is between 650 and 900 nm and the half-peak width is 120 nm.
Embodiment 5
Novel Cr3+The near infrared fluorescent powder doped with fluoride is made of solid powder and has the molecular formula of Li3K2.97Ga1.95F12:0.05Cr3+,0.03Nd3+. The preparation method comprises the following steps:
(1) weighing Ga according to stoichiometric ratio2O3:0.3749g, Cr(NO3)3·9H2O:0.048g,LiF:0.3256g,KF:0.2584g,Nd2O30.057 g. The raw materials are sequentially added into a polytetrafluoroethylene container and fully stirred for 4 hours.
(2) Putting the polytetrafluoroethylene container into a reaction kettle, putting the reaction kettle into a heating furnace for heating, heating to 180 ℃ at the heating rate of 2 ℃/min, preserving the heat for 12 hours, and then cooling to room temperature along with the furnace;
(3) washing the product obtained in the step (2) with acetic acid, pure water and absolute ethyl alcohol twice respectively, centrifuging in a centrifuge with the rotating speed of 3400r/min, drying at 80 ℃, and sieving to obtain the novel Cr3+Doped fluoride near-infrared fluorescent powder.
The near-infrared fluorescent powder obtained in the embodiment is excited under 460 nm blue light and a fluorescence spectrum is tested, and the result shows that the emission peak of the obtained fluorescent powder is between 650 and 900 nm, and the half-peak width is 115 nm.
Embodiment 6
Novel Cr3+The near infrared fluorescent powder doped with fluoride is made of solid powder and has the molecular formula of Li3Na3Al0.49Ga0.49In0.49Sc0.49F12:0.04Cr3+. The preparation method comprises the following steps:
(1) weighing Al according to stoichiometric ratio2O3:0.0862g,Ga2O3:0.1002g,In2O3:0.1535g,Sc2O3:0.1246g,Cr(NO3)3·9H2O: 0.036g, LiF: 0.3565g, NaF: 0.3882 g. The raw materials are sequentially added into a polytetrafluoroethylene container and fully stirred for 2 hours.
(2) Putting the polytetrafluoroethylene container into a reaction kettle, putting the reaction kettle into a heating furnace for heating, heating to 220 ℃ at the heating rate of 2.5 ℃/min, preserving the heat for 20 h, and then cooling to room temperature along with the furnace;
(3) washing the product obtained in the step (2) with acetic acid, pure water and absolute ethyl alcohol twice respectively, centrifuging in a centrifuge with the rotation speed of 3500r/min, drying at 80 ℃, and sieving to obtain the novel Cr3+Doped fluoride near-infrared fluorescent powder.
The near-infrared fluorescent powder obtained in the embodiment is excited under 460 nm blue light and a fluorescence spectrum is tested, and the result shows that the emission peak of the obtained fluorescent powder is between 650 and 900 nm, and the half-peak width is 110 nm.
Embodiment 7
Novel Cr3+The near infrared fluorescent powder doped with fluoride is made of solid powder and has the molecular formula of Li3Na3Ga0.95F12:0.05Cr3+,0.01Yb3+. The preparation method comprises the following steps:
(1) weighing Al according to stoichiometric ratio2O3:0.204g,Cr(NO3)3·9H2O:0.048g,LiF:0.1556g,NaF:0.2519g,0.038 Yb2O3g. The raw materials are sequentially added into a polytetrafluoroethylene container and fully stirred for 3 hours.
(2) Putting the polytetrafluoroethylene container into a reaction kettle, putting the reaction kettle into a heating furnace for heating, heating to 180 ℃ at the heating rate of 5 ℃/min, preserving heat for 12 hours, and then cooling to room temperature along with the furnace;
(3) washing the product obtained in the step (2) with acetic acid, pure water and absolute ethyl alcohol twice respectively, centrifuging in a centrifuge with the rotation speed of 3500r/min, drying at 90 ℃, and sieving to obtain the novel Cr3+Doped fluoride near-infrared fluorescent powder.
The near-infrared fluorescent powder obtained in the embodiment is excited under 460 nm blue light and a fluorescence spectrum is tested, and the result shows that the emission peak of the obtained fluorescent powder is between 650 and 1100 nm, and the half-peak width is 400 nm.
Finally, it should be noted that: it should be understood that the above examples are only for clearly illustrating the present invention and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications of the invention may be made without departing from the scope of the invention.