WO2012164024A1 - Process for continuously preparing rare earth doped fluorescent nanoparticles, their solution and system therefor - Google Patents

Process for continuously preparing rare earth doped fluorescent nanoparticles, their solution and system therefor Download PDF

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Publication number
WO2012164024A1
WO2012164024A1 PCT/EP2012/060258 EP2012060258W WO2012164024A1 WO 2012164024 A1 WO2012164024 A1 WO 2012164024A1 EP 2012060258 W EP2012060258 W EP 2012060258W WO 2012164024 A1 WO2012164024 A1 WO 2012164024A1
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Prior art keywords
rare earth
earth doped
solution
doped fluorescent
microreactor
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PCT/EP2012/060258
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French (fr)
Inventor
Min FU
Ying Ying
Tao Liu
Jianping Liao
Leslaw Mleczko
Frank Rauscher
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Bayer Technology Services Gmbh
Bayer Technology And Engineering (Shanghai) Co. Ltd.
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Publication of WO2012164024A1 publication Critical patent/WO2012164024A1/en

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    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
    • C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
    • C09K11/77—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals
    • C09K11/7766—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals containing two or more rare earth metals
    • C09K11/7777—Phosphates
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
    • C01F17/00—Compounds of rare earth metals
    • C01F17/30—Compounds containing rare earth metals and at least one element other than a rare earth metal, oxygen or hydrogen, e.g. La4S3Br6
    • C01F17/36—Compounds containing rare earth metals and at least one element other than a rare earth metal, oxygen or hydrogen, e.g. La4S3Br6 halogen being the only anion, e.g. NaYF4
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
    • C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
    • C09K11/77—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals
    • C09K11/7766—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals containing two or more rare earth metals
    • C09K11/7772—Halogenides
    • C09K11/7773—Halogenides with alkali or alkaline earth metal
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
    • C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
    • C09K11/77—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals
    • C09K11/7766—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals containing two or more rare earth metals
    • C09K11/778—Borates
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
    • C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
    • C09K11/77—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals
    • C09K11/7783—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals containing two or more rare earth metals one of which being europium
    • C09K11/7795—Phosphates
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2002/00—Crystal-structural characteristics
    • C01P2002/50—Solid solutions
    • C01P2002/52—Solid solutions containing elements as dopants
    • C01P2002/54—Solid solutions containing elements as dopants one element only
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2002/00—Crystal-structural characteristics
    • C01P2002/70—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data
    • C01P2002/72—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data by d-values or two theta-values, e.g. as X-ray diagram
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2002/00—Crystal-structural characteristics
    • C01P2002/80—Crystal-structural characteristics defined by measured data other than those specified in group C01P2002/70
    • C01P2002/84—Crystal-structural characteristics defined by measured data other than those specified in group C01P2002/70 by UV- or VIS- data
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/01—Particle morphology depicted by an image
    • C01P2004/04—Particle morphology depicted by an image obtained by TEM, STEM, STM or AFM
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/60—Particles characterised by their size
    • C01P2004/64—Nanometer sized, i.e. from 1-100 nanometer

Definitions

  • the present invention relates to a process for continuously preparing rare earth doped fluorescent nanoparticles, their solution, and a system therefor.
  • the semiconductor nanoparticles can be divided into two categories: the semiconductor nanoparticles, and the rare earth doped fluorescent nanoparticles.
  • the rare earth doped fluorescent nanoparticles have the features that their absorption and luminescent properties simply depend on the components of nanoparticles, rather than the size and distribution of nanoparticles.
  • the rare earth doped fluorescent nanoparticles have been extensively employed in many fields, such as functional films, biological labelling, solar cells, laser, high density storage, submarine communications, large screen display, detection, light-emitting diodes, etc.
  • a common process for preparing rare earth doped fluorescent nanoparticles is the solvent method.
  • a cation source compound and an anion source compound are reacted at a temperature of normally above 200°C for several hours, with a high boiling point solvent as a reaction medium and surfactant.
  • La(N0 3 )- 7H 2 0 and EUCI 3 H 2 O as cation source compounds phosphoric acid as an anion source compound, 3-ethyl hexyl phosphate as an organic solvent for controlling the crystal growth, with trioctylamine added therein as a chelate to synthesize CePO t: Tb fluorescent nanoparticles over a period of 16 hours of reaction at 200°C. These fluorescent nanoparticles had a particle size of 5 nm. They also synthesized LaPO t: Eu fluorescent nanoparticles by the same process (J. Phys. Chem. B 2000, 104, 2824-2828).
  • US20030032192A1 discloses a solvothermal process for synthesizing rare earth doped fluorescent nanoparticles on the basis of the batch processing.
  • a cation source compound, an anion source compound and at least one organic solvent for controlling the growth of crystal are mixed to form a mixture solution, and reacted at a temperature above 200 °C for more than 4 hours.
  • the rare earth doped fluorescent nanoparticles obtained by this process have a high crystallinity, monodispersion, a small particle size (lower than 20 nm), a high luminous intensity and a high production yield.
  • the present invention provides a process for continuously preparing a rare earth doped fluorescent nanoparticle solution.
  • the process comprises the following steps of:
  • said microreactor comprises a micromixing device and a micro heat exchanging device, with said micromixing device being used for continuously mixing said mixture solution, and said micro heat exchanging device being used for adjusting the temperature of said microreactor to a predetermined temperature.
  • the process further comprises the step of: controlling the pressure of said microreactor, so as to maintain the rare earth doped fluorescent nanoparticle solution in a liquid phase.
  • the pressure in said microreactor is from 1 bar to 100 bar, preferably from 1 bar to 30 bar, and more preferably from 1 bar to 10 bar.
  • Said rare earth doped fluorescent nanoparticles are selected from one of:
  • Ln represents a lantlianide element, Y or Sc
  • D represents Ba, Sr or Ca
  • E represents Cu, Ag, Eu, Bi, Al or Au
  • G represents Pr, Tm, Er, Yb or Ho
  • Q represents Gd, Y, Li or K
  • W represents Tb or Dy
  • A is selected from one or more of Li, Na, K, Rb, Mgo.5, Bao.5, Cao.5 and S10.5
  • B represents a lanthanide element.
  • Said rare earth doped fluorescent nanoparticles are preferably selected from one of:
  • Said rare earth doped fluorescent nanoparticles are preferably selected from one or more of:
  • G represents Pr, Tm, Er or Ho.
  • the predetermined temperature of said microreactor is above 200°C, preferably 250°C to 400°C, and more preferably 250°C to 340°C.
  • the predetermined residence time of said mixture solution in said microreactor is 30s to 7200s, preferably 150s to 3600s, and more preferably 600s to 2400s.
  • At least one pre-micro heat exchanger is installed, and said pre-micro heat exchanger is used for heating said mixture solution.
  • Said mixture solution can be heated by said pre-micro heat exchanger to a temperature higher than or equal to the predetermined temperature of said microreactor, for example, above 200°C, preferably 250°C to 400°C, and more preferably 250°C to 360°C.
  • the residence time of said mixture solution in said pre-micro heat exchanger is 9s to 900s, preferably 0.18s to 72s, and more preferably 0.9 s to 36 s.
  • At least one post-micro heat exchanger is installed, and said post-micro heat exchanger is used for cooling the rare earth doped fluorescent nanoparticle solution to a temperature lower than the predetermined temperature of said microreactor, for example, below 200°C, and preferably below 150°C.
  • the residence time of said rare earth doped fluorescent nanoparticle solution in the post-micro heat exchanger is from 9s to 900s, preferably 0.18s to 72s, and more preferably 0.9s to 36s.
  • Said mixture solution comprises water.
  • the existence of water leads to the formation of rare earth doped fluorescent nanoparticles of rod shape.
  • Said water can be either from the cation source compound containing water, or the one added directly.
  • rare earth doped fluorescent nanoparticles of spherical shape can be produced.
  • Said rare earth doped fluorescent nanoparticles are metal salt nanoparticles, which comprise one matrix nanocrystal carried by at least one dopant.
  • Said matrix crystal is selected from one or more of phosphates, vanadates, borates, silicates and fluorides.
  • Said cation element of said matrix crystal is selected from one or more of IA or IIA main group elements and rare earth elements.
  • Said dopant is selected from one or more of lanthanide elements, Y and Sc.
  • the present invention provides a process for continuously preparing rare earth doped fluorescent nanoparticles.
  • the process comprises the following steps of:
  • Said polar solvent is selected from one or more of methanol, ethanol, isopropanol, butanol, methyl ethyl ketone and acetone.
  • the present invention provides a system for continuously preparing a rare earth doped fluorescent nanoparticle solution.
  • the system comprises:
  • a mixer for mixing a cation source compound, an anion source compound, and at least one solvent for controlling the crystal growth of said rare earth doped fluorescent nanoparticles to form a mixture solution;
  • microreactor for maintaining said mixture solution for a predetermined period of time at a predetermined temperature, so as to obtain said rare earth doped fluorescent nanoparticle solution
  • said microreactor comprises a micromixing device and a micro heat exchanging device, with said micromixing device being used for continuously mixing said mixture solution, and said micro heat exchanging device being used for adjusting the temperature of said microreactor to said predetermined temperature; a post-micro heat exchanger for cooling said rare earth doped fluorescent nanoparticle solution;
  • a pressure controller for controlling the pressure of said system, so as to maintain the mixture solution and said rare earth doped fluorescent nanoparticle solution in a liquid phase.
  • the present invention provides a system for continuously preparing rare earth doped fluorescent nanoparticles.
  • the system comprises:
  • a mixer for mixing a cation source compound, an anion source compound, and at least one solvent for controlling the crystal growth of said rare earth doped fluorescent nanoparticles to form a mixture solution;
  • At least one microreactor for maintaining said mixture solution for a predetermined
  • said microreactor comprises a micromixing device and a micro heat exchanging device, with said micromixing device being used for continuously mixing said mixture solution, and said micro heat exchanging device being used for adjusting the temperature of said microreactor to said predetermined temperature; a post-micro heat exchanger for cooling said rare earth doped fluorescent nanoparticle solution;
  • a pressure controller for controlling the pressure of said system, so as to maintain the mixture solution and said rare earth doped fluorescent nanoparticle solution in a liquid phase
  • a mixing device for mixing said rare earth doped fluorescent nanoparticle solution and a polar solvent to form a suspension
  • a separating device for separating said suspension, so as to obtain said rare earth doped fluorescent nanoparticles.
  • the size of the internal channel of said microreactor is 10 ⁇ to 2000 ⁇ , and preferably 25 ⁇ to 1000 ⁇ .
  • the specific surface area of said microreactor is not less than 800 1/m, preferably not less than 1000 1/m, and further preferably not less than 1200 1/m.
  • the specific surface area of said pre-micro heat exchanger is not less than 20,000 1/m, preferably not less than 25,000 1/m, and more preferably not less than 30,000 1/m.
  • the specific surface area of said post-micro heat exchanger is not less than 20,000 1/m, preferably not less than 25,000 1/m, and more preferably not less than 30,000 1/m.
  • Said pre-micro heat exchanger and post-micro heat exchanger can be identical or different.
  • the system is equipped with at least one pressure controller, said pressure controller is used for controlling the pressure of said system, and the pressure of said system is 1 bar to 100 bar, preferably 1 bar to 30 bar, and more preferably 1 bar to 10 bar.
  • the mixer in said system for continuously preparing rare earth doped fluorescent nanoparticles or their solution is a micromixer, which can be used for mixing more than two streams of fluid.
  • the size of the internal channel of said micromixer is 10 ⁇ to 2000 ⁇ , and preferably 25 ⁇ to 1000 ⁇ .
  • the present invention has the following features:
  • a microreactor is used to realize the continuous preparing of
  • the rare earth doped fluorescent nanoparticles with different morphologies are obtained by way of changing cation source and/or controlling the water content in the mixture solution.
  • the microreactor applied has a micro heat exchanging device and a micro mixing device.
  • the micro heat exchanging device ensures a very large specific surface area, with a very large heat exchange and mixing efficiency; the micro mixing device improves the lateral disturbance of the mixture solution, thus effectively reducing the fluid velocity distribution of the mixture solution within the reaction channel and making the residence time of the mixture solution in the microreactor uniform, so as to ensure the uniform particle size of the fluorescent nanoparticles.
  • a solvent is employed, which is a high temperature resistant solvent for controlling the crystal growth of said rare earth doped fluorescent nanoparticles, and allows the reaction to be carried out at a high reaction temperature. Furthermore, the introduction of a pressure controller allows the reaction to be carried out at a higher reaction temperature, reducing the reaction time and improving the crystallinity of the fluorescent nanoparticles.
  • Fig. 1 is a schematic diagram of the process for preparing rare earth doped fluorescent nanoparticles, using a microreactor according to an embodiment of the present invention.
  • Fig. 2 is a schematic diagram of the process for preparing rare earth doped fluorescent nanoparticles, using a microreactor and a post-micro heat exchanger according to an embodiment of the present invention.
  • Fig. 3 is a schematic diagram of the process for preparing rare earth doped fluorescent nanoparticles, using a microreactor, a pre-micro heat exchanger, a microreactor, a post-micro heat exchanger, and a pressure controller according to an embodiment of the present invention.
  • Fig. 4 is a schematic diagram of the process for preparing rare earth doped fluorescent nanoparticles, through the introduction of a polar solvent according to an embodiment of the present invention.
  • Fig. 5 is a transmission electron microscope photograph of sample 5 CePO Tb fluorescent nanoparticles obtained according to an embodiment of the present invention.
  • Fig. 6 is a transmission electron microscope photograph of sample 8 CePO Tb fluorescent nanoparticles obtained according to an embodiment of the present invention.
  • Fig. 7 is a transmission electron microscope photograph of sample 12 LaPO Eu fluorescent nanoparticles obtained according to an embodiment of the present invention.
  • Fig. 8 is a transmission electron microscope photograph of sample 18 LaPO Eu fluorescent nanoparticles obtained according to an embodiment of the present invention.
  • Fig. 9 is a transmission electron microscope photograph of sample 19 LaPO Eu fluorescent nanoparticles obtained according to an embodiment of the present invention.
  • Fig. 10 is a transmission electron microscope photograph of sample 20 LaPO Eu fluorescent nanoparticles obtained according to an embodiment of the present invention.
  • Fig. 11 is a transmission electron microscope photograph of sample 31 NaYF Yb: Er fluorescent nanoparticles obtained according to an embodiment of the present invention.
  • Fig. 12 is an absorption spectrum of CePO Tb fluorescent nanoparticles obtained according to an embodiment of the present invention.
  • Fig. 13 is an absorption spectrum of LaPO Eu rare earth doped fluorescent nanoparticles obtained according to an embodiment of the present invention.
  • Fig. 14 is a transmission electron microscope photograph of sample 14 CePO Tb fluorescent nanoparticles obtained according to an embodiment of the present invention.
  • a cation source compound, an anion source compound, and at least one solvent for controlling the crystal growth of said rare earth doped fluorescent nanoparticles are mixed to form a mixture solution, and the mixture solution is maintained in a microreactor for a predetermined period of time at a predetermined temperature, so as to obtain said rare earth doped fluorescent nanoparticle solution, wherein the microreactor comprises a micromixing device and a micro heat exchanging device. At the front end of said microreactor, at least
  • one pre-micro heat exchanger is installed, heating said mixture solution to above 200°C; at the rear end of the microreactor, at least one post-micro heat exchanger is installed, cooling said rare earth doped fluorescent nanoparticle solution to below said predetermined temperature.
  • the above-mentioned rare earth doped fluorescent nanoparticle solution is drawn from the microreactor and collected; a polar solvent is added therein to form a suspension; the suspension is separated by centrifugation and after centrifugal sedimentation the upper layer of the solution is removed; the above procedures are repeated in order to wash the fluorescent nanoparticles, obtaining purified rare earth doped fluorescent nanoparticle precipitates; after drying in a vacuum furnace at a predetermined temperature for several hours, the rare earth doped fluorescent nanoparticles are obtained.
  • Fig. 1 is a process flow diagram according to an embodiment of the present invention.
  • a mixture solution is fed into a microreactor 100 by an injection pump 600, and a solution of rare earth doped fluorescent nanoparticles is obtained.
  • Fig. 2 is a process flow diagram according to an embodiment of the present invention.
  • a cation precursor solution is sent into the micromixer 400 via an injection pump 600a; an anion precursor solution is fed into the micromixer 400 by another injection pump 600b, and the cation precursor solution and the anion precursor solution are mixed in the micromixer 400 to form a mixture solution.
  • the mixture solution flows through the microreactor 100 and is reacted, obtaining a rare earth doped fluorescent nanoparticle solution, and the rare earth doped fluorescent nanoparticle solution flows through a post-micro heat exchanger 300 and is cooled to room temperature.
  • Fig. 3 is a process flow diagram according to an embodiment of the present invention.
  • a cation precursor solution is sent into the micromixer 400 via an injection pump 600a; an anion precursor solution is sent into the micromixer 400 via another injection pump 600b, and the cation precursor solution and the anion precursor solution are mixed in the micromixer 400 to form a mixture solution.
  • the mixture solution is heated to above 200°C by a pre-micro heat exchanger 200, and then sent into a microreactor 100 and reacted, obtaining a rare earth doped nanoparticle solution; the rare earth doped fluorescent nanoparticle solution is sent into a post-micro heat exchanger 300 and cooled to room temperature.
  • a pressure controller 500 is installed at the rear end of the post-micro heat exchanger 300, thus maintaining said mixture solution and rare earth doped nanoparticle solution in a liquid phase.
  • Fig. 4 is a process flow diagram according to an embodiment of the present invention.
  • a polar solvent is sent into the system via an injection pump 600c, and mixed with the cooled rare earth doped fluorescent nanoparticle solution in a micromixer 700 to form a suspension.
  • the rare earth doped fluorescent nanoparticle solution is preferably cooled to a temperature below 100°C, and the rare earth doped fluorescent nanoparticle solution is more preferably below 50°C.
  • the solvent used for controlling the crystal growth of said rare earth doped fluorescent nanoparticles is selected from one or more of alkyl phosphate, dialkyl phosphate, trialkyl phosphate, trialkylphosphine and trialkylphosphine oxide.
  • the solvent used for controlling the crystal growth of said rare earth doped fluorescent nanoparticles is preferably selected from one or more of trialkyl phosphate, trialkylphosphine and trialkylphosphine oxide.
  • the solvent used for controlling the crystal growth of said rare earth doped fluorescent nanoparticles is preferably selected from one or more of trialkyl phosphate, preferably tributyl phosphate, and trioctyl phosphate; trialkylphosphine, preferably triethylphosphine, tripropylphosphine, tributylphosphine, tri-sec-butyl phosphine, triamylphosphine, trihexylphosphine, and trioctylphosphine; trialkylphosphine oxide, triethylphosphine oxide, tripropylphosphine oxide, tributylphosphine oxide, tri-sec-butyl phosphine oxide, triamylphosphine oxide, trihexylphosphine oxide and trioctylphosphine oxide.
  • trialkylphosphine preferably triethylphosphine, tripropylphosphine
  • Said cation source compound is selected from one or more of chloride salts, bromide salts, acetate salts, nitrate salts, fluoride salts, iodide salts, trifluoroacetate salts, chloride salt hydrates, bromide salt hydrates, acetate salt hydrates, nitrate salt hydrates, fluoride salt hydrates, iodide salt hydrates, trifluoroacetate salt hydrates and metal oxides.
  • Said anion source compound is selected from one or more of free acids containing an anion source, and free acids containing the anion source with an organic compound which can release anions at the reaction temperature.
  • Said anion source compound is preferably selected from one or more of phosphoric acid, boric acid, sulphuric acid, silicic acid, sodium fluoride, Ln(CF 3 COO) 3 (Ln is selected from one or more of Li, Na, K, Rb, Mgo.s, Bao.s, Cao.s or Sro.s, a lanthanide element, Y or Sc), NaF, NH4HF2, NH4F and sodium metavanadate.
  • Said mixture solution further contains metal chelates.
  • Said metal chelates are selected from one or more of dihexyl ether, diphenyl ether, dibenzyl ether, dioctyl ether, dibutyl ether, dipentyl ether, diheptyl ether, diisoamyl ether, ethylene glycol dibutyl ether, diethylene glycol dibutyl ether, hexadecane, octadecane, icosane, tetradecane, dihexylamine, trioctylamine, di(2-ethylhexyl)amine and tri(2-ethylhexyl)amine.
  • Said mixture solution can be obtained by directly mixing a cation source compound, an anion source compound, and at least one solvent for controlling the crystal growth of said rare earth doped fluorescent nanoparticles, and can also be obtained by mixing a cation precursor solution and an anion precursor solution.
  • the concentration ranges of each of the component are as follows:
  • the molar concentration of the cation source compound is 0.001 mol/L to 2.5 mol/L, preferably 0.01 mol/L to 0.7 mol/L, and more preferably 0.05 mol/L to 0.4 mol/L.
  • the molar concentration of the anion source compound is 0.001 mol/L to 2.5 mol/L, preferably 0.01 mol/L to 0.7 mol/L, and more preferably 0.05 mol/L to 0.4 mol/L.
  • the molar ratio of the cation source compound to the anion source compound is more than 0.5, preferably 0.5 to 10, and more preferably 0.8 to 5.
  • said cation source compound and/or anion source compound is a solid or a viscous liquid at room temperature
  • the compounds are required to be heated in a heatable container into a liquid, and the range of the heating temperature is from room temperature to 200°C, and preferably from room temperature to 100°C.
  • the cation precursor solution contains a cation source compound and at least one solvent for controlling the crystal growth of the rare earth doped fluorescent nanoparticles; said anion precursor solution contains an anion source compound and at least one solvent for dispersing the anion source compound.
  • the process for preparing said cation precursor solution comprises the following steps of: mixing a cation source compound and at least one solvent for controlling the crystal growth of the rare earth doped fluorescent nanoparticles, and stirring the same until the cation source compound is completely dissolved.
  • a low boiling point polar solvent is added therein, which aids the dissolution of said cation source compound; furthermore, a metal chelate is optionally added therein, which aids the dissolution of the cation source compound, and replaces the crystal water in the cation source compound; the low boiling point solvent is removed by distillation; the crystal water in the above-mentioned solution can either be removed or retained.
  • said cation precursor is a solid or a viscous liquid at room temperature
  • the compounds are required to be heated in a heatable container into a liquid, and the range of the heating temperature is from room temperature to 200°C, and preferably from room temperature to 100°C.
  • Said low boiling point polar solvent is selected from one or more of methanol, ethanol, propanol, isopropanol and butanol.
  • the process for preparing said anion precursor solution comprises the following steps of: mixing an anion source compound and at least one solvent for dispersing or dissolving said anion source compound, heating, and stirring the same until the formation of a transparent and homogeneous solution.
  • the compounds are required to be heated in a heatable container into a liquid, and the range of the heating temperature is from room temperature to 200°C, and preferably from room temperature to 100°C.
  • the solvent for dispersing said anion source compound is selected from one or more of alkyl phosphate, dialkyl phosphate, trialkyl phosphate, trialkylphosphine, trialkylphosphine oxide, dihexyl ether, diphenyl ether, dibenzyl ether, dioctyl ether, dibutyl ether, dipentyl ether, diheptylether, diisoamyl ether, ethylene glycol dibutyl ether, diethylene glycol dibutyl ether, hexadecane, octadecane, icosane, tetradecane, dihexylamine, trioctylamine, di(2-ethylhexyl)amine and tri(2-ethylhexyl)amine.
  • Said cation precursor solution and anion precursor solution can be mixed by either traditional mixing, or mixed after being sent into a micromixer by a constant flow pump.
  • Said constant-flow pump can be selected from HPLC pump, plunger pump, etc.
  • the concentration ranges of each of the substances are as follows:
  • the molar concentration of the cation source compound is 0.001 mol/L to 2.5 mol/L, preferably 0.01 mol/L to 0.7 mol/L, and more preferably 0.05 mol/L to 0.4 mol/L.
  • the molar concentration of the anion source compound is 0.001 mol/L to 2.5 mol/L, preferably 0.01 mol/L to 0.7 mol/L, and more preferably 0.05 mol/L to 0.4 mol/L.
  • the molar ratio of the cation source compound to the anion source compound is more than 0.5, preferably 0.5 to 10, and more preferably 0.8 to 5.
  • the temperature of said mixture solution is lower than the predetermined temperature of the microreactor, preferably below 200°C, and more preferably below 150°C.
  • the rare earth doped fluorescent nanoparticles prepared in the present invention have been extensively used in the fields such as functional films, biological labelling, solar cells, laser, high density storage, submarine communications, large screen display, detecting, and light-emitting diodes, etc.
  • the regular experimental conditions are generally followed, for example the conditions in operation manuals in catalytic chemistry, or the conditions as suggested by the manufacturers.
  • the microreactor is a sandwich micro reactor produced by Ehrfeld Mikrotechnik Bayer Technology Services GmbH, with a volume of V ⁇ 30 ml and an area of A ⁇ 0.03 m 2 .
  • the micromixer is a valve micromixer produced by Ehrfeld Mikrotechnik Bayer Technology Services GmbH or a T mixer made in house.
  • the valve micromixer has a length of 1000 ⁇ and a width of 210 ⁇ .
  • the pressure controller is selected from a pressure controller from Swagelok (USA) or a pressure controller from Ehrfeld Mikrotechnik Bayer Technology Services GmbH.
  • the rare earth doped fluorescent nanoparticles obtained are diluted by chloroform, and then subject to optical tests.
  • a Specord 40 (Analytik Jena) UV-visible Spectrophotometer is used for testing the excitation spectrum of samples; and for the same solution, a Fluorolog 3-22 ( HORIBA Jobin Yvon) fluorescence spectrophotometer is used for fluorescence spectrum testing. During the measurement of fluorescence spectrum, the excitation wavelength is
  • a copper screen is dipped in a solution of rare earth doped fluorescent nanoparticles which have been washed in toluene, and after air drying, the transmission electron microscope photograph obtained by a CM 20 (Philips) field emission transmission electron microscope is used.
  • trioctylphosphine oxide 44 g of trioctylphosphine oxide and 48 ml of trioctylphosphine were mixed, and the mixture was heated in a container under stirring to 80°C until a transparent homogeneous solution was
  • trioctylphosphine 40 ml of trioctylphosphine were mixed, and the mixture was stirred in another container at room temperature until a homogeneous anion precursor solution was formed;
  • the cation precursor solution and anion precursor solution were preheated to 60°C respectively, then sent respectively into a T micromixer by injection pumps at a certain volume flow rate (shown in Table 1) and mixed to form a mixture solution.
  • the mixture solution was successively sent through the pre-micro heat exchanger, the microreactor, the post-micro heat exchanger and the pressure controller, and the rare earth doped fluorescent nanoparticle solution was obtained after the reaction, with the process flowchart shown in Fig. 3.
  • the predetermined temperatures of the pre-micro heat exchanger and microreactor are shown in Table 1.
  • the predetermined temperature of the post-micro heat exchanger was set at room temperature.
  • the predetermined residence time of the mixture solution in the microreactor is shown in Table 1 and the pressure of the system is shown in Table 1.
  • the rare earth doped fluorescent nanoparticle solution was drawn from the system, and collected, to which a mixture solution of methanol and isopropanol (the volume ratio of methanol to isopropanol was 1: 10) of volume 4 times that of the solution containing rare earth doped fluorescent nanoparticles was added and mixed to form a suspension.
  • the suspension was subjected to centrifugal sedimentation; after that the upper layer solution was removed, obtaining the rare earth doped fluorescent nanoparticle precipitates; the above washing procedure was repeated 3 times and the purified rare earth doped fluorescent nanoparticle precipitates were obtained.
  • the rare earth doped fluorescent nanoparticle precipitates were dried in a vacuum oven at 60°C for 3 hours, and the rare earth doped fluorescent nano fluorescent particles were obtained.
  • Table 1 shows the preparation conditions for rare earth doped fluorescent nanoparticles.
  • Fig. 12 shows the absorption spectrum of the rare earth doped fluorescent nanoparticle sample Yl.
  • trioctylphosphine oxide 44 g was mixed, and the mixture was heated in a container under stirring to 80°C until a transparent homogeneous solution was formed.
  • 22.5 mmol of CeCi 3 -7H20 and 7.5 mmol of TbCi 3 -6H20 were mixed with the above solution, and distilled under vacuum at 50°C to remove water content therein, and a cation precursor solution was formed;
  • the cation precursor solution and anion precursor solution were preheated to 60°C, and then sent respectively into a T micromixer by injection pumps at a certain volume flow rate (shown in Table 2) to form a mixture solution.
  • the mixture solution was successively sent through the pre-micro heat exchanger, the microreactor, the post-micro heat exchanger and the pressure controller, and the rare earth doped fluorescent nanoparticle solution was obtained after the reaction.
  • the predetermined temperatures of the pre-micro heat exchanger and microreactor were 320°C.
  • the predetermined temperature of the post-micro heat exchanger was set at room temperature.
  • the predetermined residence time of the mixture solution in the microreactor is shown in Table 2, with the pressure of the system being 5 bar.
  • the rare earth doped fluorescent nanoparticle solution was drawn from the system, and collected, to which a mixture solution of methanol and isopropanol (the volume ratio of methanol to isopropanol is 1: 10) of volume 4 times that of the solution containing rare earth doped fluorescent nanoparticles was added and mixed to form a suspension.
  • the suspension was subjected to centrifugal sedimentation; after that the upper layer solution was removed, obtaining the rare earth doped fluorescent nanoparticle precipitates; the above washing procedure was repeated 3 times and the purified rare earth doped fluorescent nanoparticle precipitates were obtained.
  • the rare earth doped fluorescent nanoparticle precipitates were dried in a vacuum oven at 60°C for 3 hours, and the rare earth doped fluorescent nanoparticles were obtained.
  • Table 2 shows the preparation conditions for rare earth doped fluorescent nanoparticles.
  • Fig. 5 shows the transmission electron microscope photograph of the rare earth doped fluorescent nanoparticle sample Y5.
  • Fig. 12 shows the absorption spectrum of the rare earth doped fluorescent nanoparticle samples Y4 and Y5.
  • trioctylphosphine oxide 44 g was mixed, and the mixture was heated in a container under stirring to 80°C until a transparent homogeneous solution was formed.
  • 22.5 mmol of CeCh ⁇ EhO and 7.5 mmol of TbCh-eEhO were mixed with the above solution, and distilled under vacuum at 50°C to remove water content therein, and a cation precursor solution was formed;
  • the cation precursor solution and anion precursor solution were preheated to 60°C, and then sent respectively into a T micromixer by injection pumps at a certain volume flow rate (shown in Table 3) to form a mixture solution.
  • the mixture solution was successively sent through the pre-micro heat exchanger, the microreactor, the post-micro heat exchanger and the pressure controller, and the rare earth doped fluorescent nanoparticle solution was obtained after the reaction.
  • the predetermined temperatures of the pre-micro heat exchanger and microreactor were 320°C.
  • the predetermined temperature of the post-micro heat exchanger was set at room temperature.
  • the predetermined residence time of the mixture solution in the microreactor is shown in Table 3, with the pressure of the system being 4 bar.
  • the rare earth doped fluorescent nanoparticle solution was drawn from the system, and collected, to which a mixture solution of methanol and isopropanol (the volume ratio of methanol to isopropanol is 1 : 10) of volume 4 times that of the solution containing rare earth doped fluorescent nanoparticles was added and mixed to form a suspension.
  • the suspension was subjected to centrifugal sedimentation; after that the upper layer solution was removed, obtaining the rare earth doped fluorescent nanoparticle precipitates.
  • the above washing procedure was repeated 3 times, and the purified rare earth doped fluorescent nanoparticle precipitates were obtained; the rare earth doped fluorescent nanoparticle precipitates were dried in a vacuum oven oven at 60°C for 3 hours, and the rare earth doped fluorescent nanoparticles were obtained.
  • Table Table 3 shows the preparation conditions for rare earth doped fluorescent nanoparticles.
  • Fig. Fig. 7 shows the transmission electron microscope photograph of the rare earth doped fluorescent nanoparticle sample Y8.
  • Fig. 12 shows the absorption spectrum of the rare earth doped fluorescent nanoparticle samples Y7 and Y9.
  • trioctylphosphine oxide 60g
  • 100 ml of octadecene 60g
  • 40 mmol of LaCi3-7H20 and 2 mmol of EuCl3 were mixed with the above solution, and distilled under vacuum at 50°C to remove water content therein, and a cation precursor solution was formed;
  • the cation precursor solution and anion precursor solution were preheated to 60°C, and then sent respectively into a T micromixer by injection pumps at a certain volume flow rate (shown in Table 4) to form a mixture solution.
  • the mixture solution was successively sent through the pre-micro heat exchanger, the microreactor, and the post-micro heat exchanger, and the rare earth doped fluorescent nanoparticle solution was obtained after the reaction.
  • the predetermined temperatures of the pre-micro heat exchanger and microreactor are shown in Table 4.
  • the predetermined temperature of the post-micro heat exchanger was set at room temperature.
  • the predetermined residence time of the mixture solution in the microreactor is shown in Table 4.
  • the rare earth doped fluorescent nanoparticle solution was drawn from the system, and collected, to which a mixture solution of methanol and isopropanol (the volume ratio of methanol to isopropanol is 1: 10) of volume 4 times that of the solution containing rare earth doped fluorescent nanoparticles was added and mixed to form a suspension.
  • the suspension was subjected to centrifugal sedimentation; after that the upper layer solution was removed, obtaining the rare earth doped fluorescent nanoparticle precipitates; the above washing procedure was repeated 3 times and the purified rare earth doped fluorescent nanoparticle precipitates were were obtained.
  • the rare earth doped fluorescent nanoparticle precipitates were dried under vacuum at 60°C for 3 hours, and the rare earth doped fluorescent nanoparticles were obtained. Table 4 shows the preparation conditions for rare earth doped fluorescent
  • Fig. 7 shows the transmission electron microscope photograph of the rare earth doped fluorescent nanoparticle sample Y12.
  • Fig. 13 shows the absorption spectrum of the rare earth doped fluorescent nanoparticle samples Y10 and Yl l .
  • the cation precursor solution and anion precursor solution were preheated to 60°C, and sent respectively into a T micromixer by injection pumps at a certain volume flow rate (shown in Table 5) to form a mixture solution.
  • Said mixture solution was made to flow through the microreactor and the post-micro heat exchanger and reacted at 320° C, and the rare earth doped fluorescent nanoparticle solution was obtained, with the process flowchart shown in Fig. 2.
  • the predetermined temperature of the post-micro heat exchanger was set at room temperature, and the predetermined residence time of the mixture solution in the microreactor is shown in Table 5.
  • the rare earth doped fluorescent nanoparticle solution was drawn from the system, and collected, to which a mixture solution of methanol and isopropanol (the volume ratio of methanol to isopropanol is 1: 10) of volume 4 times that of the solution containing rare earth doped fluorescent nanoparticles was added and mixed to form a suspension.
  • the suspension was subjected to centrifugal sedimentation; after that the upper layer solution was removed, obtaining the rare earth doped fluorescent nanoparticle precipitates; the above washing procedure was repeated 3 times and the purified rare earth doped fluorescent nanoparticle precipitates were
  • the rare earth doped fluorescent nanoparticle precipitates were dried under vacuum at 60°C for 3 hours, and the rare earth doped fluorescent nanoparticles were obtained.
  • Table 5 shows the preparation conditions for rare earth doped fluorescent nanoparticles.
  • the cation precursor solution and anion precursor solution were preheated to 60°C, and sent respectively into a T micromixer by injection pumps at a certain volume flow rate (shown in Table 6) to form a mixture solution.
  • Said mixture solution was made to flow through the microreactor and the post-micro heat exchanger and reacted at 300° C, and the rare earth doped fluorescent nanoparticle solution was obtained.
  • the predetermined temperature of the post-micro heat exchanger was set at room temperature.
  • the predetermined residence time of the mixture solution in the microreactor is shown in Table 6.
  • the rare earth doped fluorescent nanoparticle solution was drawn from the system, and collected, to which a mixture solution of methanol and isopropanol (the volume ratio of methanol to isopropanol is 1 : 10) of volume 4 times that of the solution containing rare earth doped fluorescent nanoparticles was added and mixed to form a suspension.
  • the suspension was subjected to centrifugal sedimentation; after that the upper layer solution was removed, obtaining the rare earth doped fluorescent nanoparticle precipitate; the above washing procedure was repeated 3 times and the purified rare earth doped fluorescent nanoparticle precipitates were were obtained.
  • the rare earth doped fluorescent nanoparticle precipitates were dried under vacuum at 60°C for 3 hours, and the rare earth doped fluorescent nanoparticles were obtained. Table 6 shows the preparation conditions for rare earth doped fluorescent
  • the cation precursor solution and anion precursor solution were preheated to 60°C, and sent respectively into a T micromixer by injection pumps at a volume flow rate of 1 ml/min to form a mixture solution.
  • Said mixture solution was made to flow through the microreactor and the post- micro heat exchanger and reacted at 300° C, and the rare earth doped fluorescent nanoparticle solution was obtained.
  • the predetermined temperature of the post-micro heat exchanger was set at room temperature.
  • the predetermined residence time of the mixture solution in the microreactor was 15 min.
  • the rare earth doped fluorescent nanoparticle solution was drawn from the system, and collected, to which a mixture solution of methanol and isopropanol (the volume ratio of methanol to isopropanol is 1 : 10) of 4 times of that of the solution containing rare earth doped fluorescent nanoparticles was added and mixed to form a suspension.
  • the suspension was subjected to centrifugal sedimentation; after that the upper layer solution was removed, obtaining the rare earth doped fluorescent nanoparticle precipitate; the above washing procedure was
  • the rare earth doped fluorescent nanoparticle precipitates were dried under vacuum at 60°C for 3 hours, and the rare earth doped fluorescent nanoparticles were obtained.
  • the cation precursor solution and anion precursor solution were preheated to 80°C, and sent respectively into a T micromixer by injection pumps at a certain volume flow rate (shown in Table 7) to form a mixture solution.
  • Said mixture solution was made to flow through the microreactor and the post-micro heat exchanger and reacted at 320°C, and the rare earth doped fluorescent nanoparticle solution was obtained.
  • the predetermined temperature of the post-micro heat exchanger was set at room temperature, and the predetermined residence time of the mixture solution in the microreactor is shown in Table 7.
  • the rare earth doped fluorescent nanoparticle solution was drawn from the system, and collected, to which a mixture solution of methanol and isopropanol (the volume ratio of methanol to isopropanol is 1: 10) of volume 4 times that of the solution containing rare earth doped fluorescent nanoparticles was added and mixed to form a suspension.
  • the suspension was centrifugal sedimentation; the upper layer solution after centrifuging and settling was removed, and the rare earth doped fluorescent nanoparticle precipitates were obtained; the above washing procedure was repeated 3 times; and the purified rare earth doped fluorescent nanoparticle precipitates were obtained.
  • the rare earth doped fluorescent nanoparticle precipitates were dried under vacuum at 60°C for 4 hours, and the rare earth doped fluorescent nanoparticles were obtained. Table 7 shows the preparation conditions for rare earth doped fluorescent nanoparticles.
  • the cation precursor solution and anion precursor solution were preheated to 80°C, and sent respectively into a T micromixer by injection pumps at a certain volume flow rate (shown in Table 8) to form a mixture solution.
  • Said mixture solution was made to flow through the microreactor and the post-micro heat exchanger and reacted at the predetermined temperature of said micro heat exchanger (shown in Table 8), and the rare earth doped fluorescent nanoparticle solution was obtained.
  • the predetermined temperature of the post-micro heat exchanger was set at room temperature, and the predetermined residence time of the mixture solution in the microreactor is shown in Table 8.
  • the rare earth doped fluorescent nanoparticle solution was drawn from the system, and collected, to which a mixture solution of methanol and isopropanol (the volume ratio of methanol to isopropanol is 1: 10) of volume 4 times that of the solution containing rare earth doped fluorescent nanoparticles was added and mixed to form a suspension.
  • the suspension was subjected to centrifugal sedimentation; after that the upper layer solution was removed, obtaining the rare earth doped fluorescent nanoparticle precipitates; the above washing procedure was repeated 4 times and the purified rare earth doped fluorescent nanoparticle precipitates were were obtained.
  • the rare earth doped fluorescent nanoparticle precipitates were dried under vacuum at 60°C for 4 hours, and the rare earth doped fluorescent nanoparticles were
  • Table 8 shows the preparation conditions for rare earth doped fluorescent nanoparticles.
  • the cation precursor solution and anion precursor solution were preheated to 80°C, and sent into a T micromixer by injection pumps at respective volume flow rates of 0.5 ml/min, and 0.5 ml/min to form a mixture solution.
  • the mixture solution was sent through the pre-micro heat exchanger, the microreactor, the post-micro heat exchanger and the pressure controller, and the rare earth doped fluorescent nanoparticle solution was obtained after the reaction.
  • the predetermined temperature of the pre-micro heat exchanger, the microreactor and the post-micro heat exchanger was set at 320°C, 300°C and 30°C, respectively.
  • the predetermined residence time of the mixture solution in the microreactor was 30 min.
  • the pressure of the system was 3 bar.
  • the methanol and isopropanol mixture (the volume ratio of methanol to isopropyl is 1 : 10) was sent by an HPLC pump at a flow rate of 4 ml/min, and mixed with the rare earth doped fluorescent nanoparticle solution in a valve micromixer, and a suspension was formed.
  • the suspension was subjected to centrifugal sedimentation; after that the upper layer solution was removed, obtaining the rare earth doped fluorescent nanoparticle precipitates.
  • the above washing procedure was repeated 3 times, and the purified rare earth doped fluorescent
  • Fig. 14 shows the transmission electron microscope photograph of the rare earth doped fluorescent nanoparticles obtained in this example.
  • the solution was sent into the T micromixer at a certain flow rate (shown in Table 9) by a high performance liquid chromatogram pump, and a mixture solution was formed.
  • the mixture solution was sent through the pre-micro heat exchanger, the microreactor, and the post-micro heat exchanger, and the rare earth doped fluorescent nanoparticle solution was obtained after the reaction.
  • the predetermined temperatures of pre-micro heat exchanger and microreactor are shown in Table 9.
  • the predetermined temperature of the post-micro heat exchanger was set at room temperature.
  • the predetermined residence time of the mixture solution in the microreactor was 15 min.
  • the rare earth doped fluorescent nanoparticle solution was drawn from the system, and collected, to which a mixture solution of methanol and cyclohexane (the volume ratio of methanol to cyclohexane is 9: 1) of volume 4 times that of the solution containing rare earth doped fluorescent nanoparticles was added and mixed to form a suspension.
  • the suspension was subjected to centrifugal sedimentation; after that the upper layer solution was removed, obtaining the rare earth doped fluorescent nanoparticle precipitates.
  • the above mixture solution was subsequently sent through the pre-micro heat exchanger and the microreactor at a volume flow rate of 1 ml/min at common temperature, and the rare earth doped fluorescent nanoparticle solution was obtained after the reaction.
  • the predetermined temperature of the pre-micro heat exchanger was 340°C
  • the predetermined temperature of the microreactor was 300°C.
  • the predetermined residence time of the mixture solution in the microreactor was 30 min.
  • the rare earth doped fluorescent nanoparticle solution was drawn from the system, collected, and cooled naturally, to which a mixture solution of methanol and isopropanol (the volume ratio of methanol to isopropanol is 1 : 10) of volume 4 times that of the solution containing rare earth doped fluorescent nanoparticles was added and mixed to form a suspension.
  • the suspension was subjected to centrifugal sedimentation, the upper layer solution after centrifuging and settling was removed, and the rare earth doped fluorescent nanoparticle precipitates were obtained.
  • the above washing procedure was repeated 4 times, and the purified rare earth doped fluorescent nanoparticle precipitates were obtained.
  • the rare earth doped fluorescent nanoparticle precipitates were dried under vacuum at 60°C for 4 hours, and the rare earth doped fluorescent nanoparticles were obtained.
  • the above mixture solution was subsequently sent through the pre-micro heat exchanger, the microreactor, and the pressure controller at a volume flow rate of 5 ml/min at common temperature, and the rare earth doped fluorescent nanoparticle solution was obtained after the reaction.
  • the predetermined temperature of the pre-micro heat exchanger was 340°C
  • the predetermined temperature of the microreactor was set as 300°C, with the system pressure being 5 bar.
  • the predetermined residence time of the mixture solution in the microreactor was 6 min.
  • the rare earth doped fluorescent nanoparticle solution was drawn from the system, collected, and cooled naturally, to which a mixture solution of methanol and isopropanol (the volume ratio of methanol to isopropanol is 1 : 10) of volume 4 times that of the solution containing rare earth doped fluorescent nanoparticles was added and mixed to form a suspension.
  • the suspension was subjected to centrifugal sedimentation; after that the upper layer solution was removed, obtaining the rare earth doped fluorescent nanoparticle precipitates.
  • the above washing procedure was repeated 4 times, and the purified rare earth doped fluorescent nanoparticle precipitates were obtained.
  • the rare earth doped fluorescent nanoparticle precipitates were dried under vacuum at 60°C for 4 hours, and the rare earth doped fluorescent nanoparticles were obtained.
  • Example 14 Preparation of CePO t: Tb fluorescent nanoparticles
  • the above mixture solution was preheated to 60°C, and subsequently sent through the pre-micro heat exchanger, the microreactor, and the post-micro heat exchanger at a volume flow rate of 1 ml/min, and the rare earth doped fluorescent nanoparticle solution was obtained after the reaction.
  • the predetermined temperature of the pre-micro heat exchanger, the microreactor and the post-micro heat exchanger was set at 300°C, 280°C and 25°C respectively, with the system pressure being 5 bar.
  • the predetermined residence time of the mixture solution in the microreactor was 30 min.
  • the methanol and isopropanol mixture (the volume ratio of methanol to isopropyl is 1 : 10) was sent by a high performance liquid chromatograph pump at a flow rate of 4 ml/min, and mixed with the rare earth doped fluorescent nanoparticle solution in a valve micromixer, and a suspension
  • Fig. 14 shows the transmission electron microscope photograph of the rare earth doped fluorescent nanoparticles obtained in this example.

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Abstract

The present invention provides a process for continuously preparing rare earth doped fluorescent nanoparticles, their solution, and a system therefor. The process for continuously preparing a rare earth doped fluorescent nanoparticle solution provided in the present invention comprises the following steps of: mixing a cation source compound, an anion source compound, and at least one solvent for controlling the crystal growth of said rare earth doped fluorescent nanoparticles to form a mixture solution; and maintaining said mixture solution in a microreactor for a predetermined period of time at a predetermined temperature, so as to obtain said rare earth doped fluorescent nanoparticle solution, wherein said microreactor comprises a micromixing device and a micro heat exchanging device, with said micromixing device being for continuously mixing said mixture solution, and said micro heat exchanging device being for adjusting the temperature of said microreactor to a predetermined temperature. The rare earth doped fluorescent nanoparticles obtained by the present invention have a uniform narrow particle size, a high crystallinity, and a good reproducibility of the product quality.

Description

Description
Process for continuously preparing rare earth doped fluorescent nanoparticles, their solution and system therefor
Technical Field
The present invention relates to a process for continuously preparing rare earth doped fluorescent nanoparticles, their solution, and a system therefor. Background Art
Common inorganic fluorescent nano-materials can be divided into two categories: the semiconductor nanoparticles, and the rare earth doped fluorescent nanoparticles. In contrast to the semiconductor nanoparticles, the rare earth doped fluorescent nanoparticles have the features that their absorption and luminescent properties simply depend on the components of nanoparticles, rather than the size and distribution of nanoparticles.
The rare earth doped fluorescent nanoparticles have been extensively employed in many fields, such as functional films, biological labelling, solar cells, laser, high density storage, submarine communications, large screen display, detection, light-emitting diodes, etc.
A common process for preparing rare earth doped fluorescent nanoparticles is the solvent method. In the solvent method, a cation source compound and an anion source compound are reacted at a temperature of normally above 200°C for several hours, with a high boiling point solvent as a reaction medium and surfactant.
There are reports describing the processes for preparing rare earth doped fluorescent nanoparticles by the solvent method. For example: K. Riwotzki et al. employed
La(N03)- 7H20 and EUCI3 H2O as cation source compounds, phosphoric acid as an anion source compound, 3-ethyl hexyl phosphate as an organic solvent for controlling the crystal growth, with trioctylamine added therein as a chelate to synthesize CePO t: Tb fluorescent nanoparticles over a period of 16 hours of reaction at 200°C. These fluorescent nanoparticles had a particle size of 5 nm. They also synthesized LaPO t: Eu fluorescent nanoparticles by the same process (J. Phys. Chem. B 2000, 104, 2824-2828).
US20030032192A1 discloses a solvothermal process for synthesizing rare earth doped fluorescent nanoparticles on the basis of the batch processing. In this process, a cation source compound, an anion source compound and at least one organic solvent for controlling the growth of crystal are mixed to form a mixture solution, and reacted at a temperature above 200 °C for more than 4 hours. The rare earth doped fluorescent nanoparticles obtained by this process have a high crystallinity, monodispersion, a small particle size (lower than 20 nm), a high luminous intensity and a high production yield. Contents of the invention
According to one embodiment of the present invention, the present invention provides a process for continuously preparing a rare earth doped fluorescent nanoparticle solution. The process comprises the following steps of:
mixing a cation source compound, an anion source compound, and at least one solvent for controlling the crystal growth of said rare earth doped fluorescent nanoparticles to form a mixture solution; and
maintaining said mixture solution in a microreactor for a predetermined period of time at a predetermined temperature, so as to obtain said rare earth doped fluorescent nanoparticle solution, wherein said microreactor comprises a micromixing device and a micro heat exchanging device, with said micromixing device being used for continuously mixing said mixture solution, and said micro heat exchanging device being used for adjusting the temperature of said microreactor to a predetermined temperature.
The process further comprises the step of: controlling the pressure of said microreactor, so as to maintain the rare earth doped fluorescent nanoparticle solution in a liquid phase.
The pressure in said microreactor is from 1 bar to 100 bar, preferably from 1 bar to 30 bar, and more preferably from 1 bar to 10 bar.
Said rare earth doped fluorescent nanoparticles are selected from one of:
LnP0 : Ce: W,
LnP04: Eu,
LnV04: Ce: W,
LnV04: Eu,
Ln(V04)x(P04)y: B (x + y = 1, wherein 0 < x < 1),
AYF4: G,
AYCU: G,
AYBr4: G,
NaQF4: Yb: B,
NaQCl4: Yb: B,
NaQBr4: Yb: B,
LnB03: Ce: W,
LnB03: Eu,
2 (YGd)B03: Eu,
DS04: B,
DS04: Mn, and
Zn2(Si04): Mn;
wherein Ln represents a lantlianide element, Y or Sc; D represents Ba, Sr or Ca; E represents Cu, Ag, Eu, Bi, Al or Au; G represents Pr, Tm, Er, Yb or Ho; Q represents Gd, Y, Li or K; W represents Tb or Dy; A is selected from one or more of Li, Na, K, Rb, Mgo.5, Bao.5, Cao.5 and S10.5; and B represents a lanthanide element.
Said rare earth doped fluorescent nanoparticles are preferably selected from one of:
LnP04: Ce: W,
LaP04: Eu,
YP04: Eu,
CeP04: Tb,
LnV04: Ce: W,
LnV04: Eu,
LiYF : Yb: G,
NaYF : Yb: G,
LnB03: Ce: W,
LnBCh: Eu, and
(YGd)B03: Eu ; wherein Ln represents a lanthanide element, Y or Sc; G represents Pr, Tm, Er, Ho; and W represents Tb or Dy.
Said rare earth doped fluorescent nanoparticles are preferably selected from one or more of:
LaP04: Ce: Tb,
LaP04: Ce: Dy,
LaP04: Eu,
CeP04: Tb,
YV04: Ce: Tb,
YV04: Ce: Dy,
YV0 : Eu,
LiYF : Yb: G,
NaYF : Yb: G,
LaB03: Ce: Tb,
YB03: Ce: Tb,
LaBC : Eu, and YB03: Eu;
wherein G represents Pr, Tm, Er or Ho.
The predetermined temperature of said microreactor is above 200°C, preferably 250°C to 400°C, and more preferably 250°C to 340°C.
The predetermined residence time of said mixture solution in said microreactor is 30s to 7200s, preferably 150s to 3600s, and more preferably 600s to 2400s.
In the front end of said micoreactor, at least one pre-micro heat exchanger is installed, and said pre-micro heat exchanger is used for heating said mixture solution.
Said mixture solution can be heated by said pre-micro heat exchanger to a temperature higher than or equal to the predetermined temperature of said microreactor, for example, above 200°C, preferably 250°C to 400°C, and more preferably 250°C to 360°C.
The residence time of said mixture solution in said pre-micro heat exchanger is 9s to 900s, preferably 0.18s to 72s, and more preferably 0.9 s to 36 s.
In the rear end of said microreactor, at least one post-micro heat exchanger is installed, and said post-micro heat exchanger is used for cooling the rare earth doped fluorescent nanoparticle solution to a temperature lower than the predetermined temperature of said microreactor, for example, below 200°C, and preferably below 150°C.
The residence time of said rare earth doped fluorescent nanoparticle solution in the post-micro heat exchanger is from 9s to 900s, preferably 0.18s to 72s, and more preferably 0.9s to 36s.
Said mixture solution comprises water. The existence of water leads to the formation of rare earth doped fluorescent nanoparticles of rod shape. Said water can be either from the cation source compound containing water, or the one added directly.
When there is no water in said mixture solution, rare earth doped fluorescent nanoparticles of spherical shape can be produced.
Said rare earth doped fluorescent nanoparticles are metal salt nanoparticles, which comprise one matrix nanocrystal carried by at least one dopant.
Said matrix crystal is selected from one or more of phosphates, vanadates, borates, silicates and fluorides.
Said cation element of said matrix crystal is selected from one or more of IA or IIA main group elements and rare earth elements.
Said dopant is selected from one or more of lanthanide elements, Y and Sc.
According to one embodiment of the present invention, the present invention provides a process for continuously preparing rare earth doped fluorescent nanoparticles. The process comprises the following steps of:
mixing a rare earth doped fluorescent nanoparticle solution prepared by any processes mentioned above with a polar solvent to form a suspension; and separating said suspension so as to obtain said rare earth doped fluorescent nanoparticles.
Said polar solvent is selected from one or more of methanol, ethanol, isopropanol, butanol, methyl ethyl ketone and acetone.
According to one embodiment of the present invention, the present invention provides a system for continuously preparing a rare earth doped fluorescent nanoparticle solution. The system comprises:
a mixer for mixing a cation source compound, an anion source compound, and at least one solvent for controlling the crystal growth of said rare earth doped fluorescent nanoparticles to form a mixture solution;
a pre-micro heat exchanger for heating said mixture solution;
at least one microreactor for maintaining said mixture solution for a predetermined period of time at a predetermined temperature, so as to obtain said rare earth doped fluorescent nanoparticle solution, wherein said microreactor comprises a micromixing device and a micro heat exchanging device, with said micromixing device being used for continuously mixing said mixture solution, and said micro heat exchanging device being used for adjusting the temperature of said microreactor to said predetermined temperature; a post-micro heat exchanger for cooling said rare earth doped fluorescent nanoparticle solution; and
a pressure controller for controlling the pressure of said system, so as to maintain the mixture solution and said rare earth doped fluorescent nanoparticle solution in a liquid phase.
According to one embodiment of the present invention, the present invention provides a system for continuously preparing rare earth doped fluorescent nanoparticles. The system comprises:
a mixer for mixing a cation source compound, an anion source compound, and at least one solvent for controlling the crystal growth of said rare earth doped fluorescent nanoparticles to form a mixture solution;
a pre-micro heat exchanger for heating said mixture solution;
at least one microreactor for maintaining said mixture solution for a predetermined
5 period of time at a predetermined temperature, so as to obtain a rare earth doped fluorescent nanoparticle solution, wherein said microreactor comprises a micromixing device and a micro heat exchanging device, with said micromixing device being used for continuously mixing said mixture solution, and said micro heat exchanging device being used for adjusting the temperature of said microreactor to said predetermined temperature; a post-micro heat exchanger for cooling said rare earth doped fluorescent nanoparticle solution;
a pressure controller for controlling the pressure of said system, so as to maintain the mixture solution and said rare earth doped fluorescent nanoparticle solution in a liquid phase;
a mixing device for mixing said rare earth doped fluorescent nanoparticle solution and a polar solvent to form a suspension; and
a separating device for separating said suspension, so as to obtain said rare earth doped fluorescent nanoparticles.
The size of the internal channel of said microreactor is 10 μιη to 2000 μηι, and preferably 25 μηι to 1000 μηι.
The specific surface area of said microreactor is not less than 800 1/m, preferably not less than 1000 1/m, and further preferably not less than 1200 1/m.
The specific surface area of said pre-micro heat exchanger is not less than 20,000 1/m, preferably not less than 25,000 1/m, and more preferably not less than 30,000 1/m.
The specific surface area of said post-micro heat exchanger is not less than 20,000 1/m, preferably not less than 25,000 1/m, and more preferably not less than 30,000 1/m.
Said pre-micro heat exchanger and post-micro heat exchanger can be identical or different.
The system is equipped with at least one pressure controller, said pressure controller is used for controlling the pressure of said system, and the pressure of said system is 1 bar to 100 bar, preferably 1 bar to 30 bar, and more preferably 1 bar to 10 bar.
The mixer in said system for continuously preparing rare earth doped fluorescent nanoparticles or their solution is a micromixer, which can be used for mixing more than two streams of fluid. The size of the internal channel of said micromixer is 10 μηι to 2000 μηι, and preferably 25 μηι to 1000 μηι.
Compared with the prior art, the present invention has the following features:
In the present invention, a microreactor is used to realize the continuous preparing of
6 rare earth doped fluorescent nanoparticles and their solution. By using the microreactor, the reaction temperature and residence time are precisely controlled, the materials are mixed exactly in accurate proportions, the reaction time is shortened without any scale effect, and the product quality has good reproducibility.
In the present invention, the rare earth doped fluorescent nanoparticles with different morphologies are obtained by way of changing cation source and/or controlling the water content in the mixture solution.
In the present invention, the microreactor applied has a micro heat exchanging device and a micro mixing device. The micro heat exchanging device ensures a very large specific surface area, with a very large heat exchange and mixing efficiency; the micro mixing device improves the lateral disturbance of the mixture solution, thus effectively reducing the fluid velocity distribution of the mixture solution within the reaction channel and making the residence time of the mixture solution in the microreactor uniform, so as to ensure the uniform particle size of the fluorescent nanoparticles.
In the present invention, a solvent is employed, which is a high temperature resistant solvent for controlling the crystal growth of said rare earth doped fluorescent nanoparticles, and allows the reaction to be carried out at a high reaction temperature. Furthermore, the introduction of a pressure controller allows the reaction to be carried out at a higher reaction temperature, reducing the reaction time and improving the crystallinity of the fluorescent nanoparticles.
Description of Drawings
Fig. 1 is a schematic diagram of the process for preparing rare earth doped fluorescent nanoparticles, using a microreactor according to an embodiment of the present invention.
Fig. 2 is a schematic diagram of the process for preparing rare earth doped fluorescent nanoparticles, using a microreactor and a post-micro heat exchanger according to an embodiment of the present invention.
Fig. 3 is a schematic diagram of the process for preparing rare earth doped fluorescent nanoparticles, using a microreactor, a pre-micro heat exchanger, a microreactor, a post-micro heat exchanger, and a pressure controller according to an embodiment of the present invention.
Fig. 4 is a schematic diagram of the process for preparing rare earth doped fluorescent nanoparticles, through the introduction of a polar solvent according to an embodiment of the present invention.
Fig. 5 is a transmission electron microscope photograph of sample 5 CePO Tb fluorescent nanoparticles obtained according to an embodiment of the present invention.
Fig. 6 is a transmission electron microscope photograph of sample 8 CePO Tb fluorescent nanoparticles obtained according to an embodiment of the present invention.
Fig. 7 is a transmission electron microscope photograph of sample 12 LaPO Eu fluorescent nanoparticles obtained according to an embodiment of the present invention.
Fig. 8 is a transmission electron microscope photograph of sample 18 LaPO Eu fluorescent nanoparticles obtained according to an embodiment of the present invention.
Fig. 9 is a transmission electron microscope photograph of sample 19 LaPO Eu fluorescent nanoparticles obtained according to an embodiment of the present invention.
Fig. 10 is a transmission electron microscope photograph of sample 20 LaPO Eu fluorescent nanoparticles obtained according to an embodiment of the present invention.
Fig. 11 is a transmission electron microscope photograph of sample 31 NaYF Yb: Er fluorescent nanoparticles obtained according to an embodiment of the present invention.
Fig. 12 is an absorption spectrum of CePO Tb fluorescent nanoparticles obtained according to an embodiment of the present invention.
Fig. 13 is an absorption spectrum of LaPO Eu rare earth doped fluorescent nanoparticles obtained according to an embodiment of the present invention.
Fig. 14 is a transmission electron microscope photograph of sample 14 CePO Tb fluorescent nanoparticles obtained according to an embodiment of the present invention.
These figures listed herein are used to further describe the particular embodiments and processes disclosed in the present invention, and the figures and the descriptions are exemplary instead of restrictive.
Particular embodiments
Hereinbelow, the present invention is further illustrated in conjunction with particular embodiments. It should be understood that these embodiments are simply used for illustrating the scope of the present invention rather than limiting the scope of the present invention. Furthermore, it should be understood that those skilled in the art can make any variation or modification after reading the teachings of the present invention, and such equivalents also fall into the scope defined in the appended claims.
A cation source compound, an anion source compound, and at least one solvent for controlling the crystal growth of said rare earth doped fluorescent nanoparticles are mixed to form a mixture solution, and the mixture solution is maintained in a microreactor for a predetermined period of time at a predetermined temperature, so as to obtain said rare earth doped fluorescent nanoparticle solution, wherein the microreactor comprises a micromixing device and a micro heat exchanging device. At the front end of said microreactor, at least
8 one pre-micro heat exchanger is installed, heating said mixture solution to above 200°C; at the rear end of the microreactor, at least one post-micro heat exchanger is installed, cooling said rare earth doped fluorescent nanoparticle solution to below said predetermined temperature.
The above-mentioned rare earth doped fluorescent nanoparticle solution is drawn from the microreactor and collected; a polar solvent is added therein to form a suspension; the suspension is separated by centrifugation and after centrifugal sedimentation the upper layer of the solution is removed; the above procedures are repeated in order to wash the fluorescent nanoparticles, obtaining purified rare earth doped fluorescent nanoparticle precipitates; after drying in a vacuum furnace at a predetermined temperature for several hours, the rare earth doped fluorescent nanoparticles are obtained.
Fig. 1 is a process flow diagram according to an embodiment of the present invention. A mixture solution is fed into a microreactor 100 by an injection pump 600, and a solution of rare earth doped fluorescent nanoparticles is obtained.
Fig. 2 is a process flow diagram according to an embodiment of the present invention.
A cation precursor solution is sent into the micromixer 400 via an injection pump 600a; an anion precursor solution is fed into the micromixer 400 by another injection pump 600b, and the cation precursor solution and the anion precursor solution are mixed in the micromixer 400 to form a mixture solution. The mixture solution flows through the microreactor 100 and is reacted, obtaining a rare earth doped fluorescent nanoparticle solution, and the rare earth doped fluorescent nanoparticle solution flows through a post-micro heat exchanger 300 and is cooled to room temperature.
Fig. 3 is a process flow diagram according to an embodiment of the present invention. A cation precursor solution is sent into the micromixer 400 via an injection pump 600a; an anion precursor solution is sent into the micromixer 400 via another injection pump 600b, and the cation precursor solution and the anion precursor solution are mixed in the micromixer 400 to form a mixture solution. The mixture solution is heated to above 200°C by a pre-micro heat exchanger 200, and then sent into a microreactor 100 and reacted, obtaining a rare earth doped nanoparticle solution; the rare earth doped fluorescent nanoparticle solution is sent into a post-micro heat exchanger 300 and cooled to room temperature. A pressure controller 500 is installed at the rear end of the post-micro heat exchanger 300, thus maintaining said mixture solution and rare earth doped nanoparticle solution in a liquid phase.
Fig. 4 is a process flow diagram according to an embodiment of the present invention. On the basis of the process flow diagram shown in figure 3, a polar solvent is sent into the system via an injection pump 600c, and mixed with the cooled rare earth doped fluorescent nanoparticle solution in a micromixer 700 to form a suspension.
The rare earth doped fluorescent nanoparticle solution is preferably cooled to a temperature below 100°C, and the rare earth doped fluorescent nanoparticle solution is more preferably below 50°C.
The solvent used for controlling the crystal growth of said rare earth doped fluorescent nanoparticles is selected from one or more of alkyl phosphate, dialkyl phosphate, trialkyl phosphate, trialkylphosphine and trialkylphosphine oxide.
The solvent used for controlling the crystal growth of said rare earth doped fluorescent nanoparticles is preferably selected from one or more of trialkyl phosphate, trialkylphosphine and trialkylphosphine oxide.
The solvent used for controlling the crystal growth of said rare earth doped fluorescent nanoparticles is preferably selected from one or more of trialkyl phosphate, preferably tributyl phosphate, and trioctyl phosphate; trialkylphosphine, preferably triethylphosphine, tripropylphosphine, tributylphosphine, tri-sec-butyl phosphine, triamylphosphine, trihexylphosphine, and trioctylphosphine; trialkylphosphine oxide, triethylphosphine oxide, tripropylphosphine oxide, tributylphosphine oxide, tri-sec-butyl phosphine oxide, triamylphosphine oxide, trihexylphosphine oxide and trioctylphosphine oxide.
Said cation source compound is selected from one or more of chloride salts, bromide salts, acetate salts, nitrate salts, fluoride salts, iodide salts, trifluoroacetate salts, chloride salt hydrates, bromide salt hydrates, acetate salt hydrates, nitrate salt hydrates, fluoride salt hydrates, iodide salt hydrates, trifluoroacetate salt hydrates and metal oxides.
Said anion source compound is selected from one or more of free acids containing an anion source, and free acids containing the anion source with an organic compound which can release anions at the reaction temperature.
Said anion source compound is preferably selected from one or more of phosphoric acid, boric acid, sulphuric acid, silicic acid, sodium fluoride, Ln(CF3COO) 3 (Ln is selected from one or more of Li, Na, K, Rb, Mgo.s, Bao.s, Cao.s or Sro.s, a lanthanide element, Y or Sc), NaF, NH4HF2, NH4F and sodium metavanadate.
Said mixture solution further contains metal chelates.
Said metal chelates are selected from one or more of dihexyl ether, diphenyl ether, dibenzyl ether, dioctyl ether, dibutyl ether, dipentyl ether, diheptyl ether, diisoamyl ether, ethylene glycol dibutyl ether, diethylene glycol dibutyl ether, hexadecane, octadecane, icosane, tetradecane, dihexylamine, trioctylamine, di(2-ethylhexyl)amine and tri(2-ethylhexyl)amine.
10 Said mixture solution can be obtained by directly mixing a cation source compound, an anion source compound, and at least one solvent for controlling the crystal growth of said rare earth doped fluorescent nanoparticles, and can also be obtained by mixing a cation precursor solution and an anion precursor solution.
When the mixture solution is obtained by directly mixing a cation source compound, an anion source compound, and at least one solvent for controlling the growth of rare earth doped fluorescent nanoparticles, the concentration ranges of each of the component are as follows:
The molar concentration of the cation source compound is 0.001 mol/L to 2.5 mol/L, preferably 0.01 mol/L to 0.7 mol/L, and more preferably 0.05 mol/L to 0.4 mol/L.
The molar concentration of the anion source compound is 0.001 mol/L to 2.5 mol/L, preferably 0.01 mol/L to 0.7 mol/L, and more preferably 0.05 mol/L to 0.4 mol/L.
In said mixture solution, the molar ratio of the cation source compound to the anion source compound is more than 0.5, preferably 0.5 to 10, and more preferably 0.8 to 5.
When said cation source compound and/or anion source compound is a solid or a viscous liquid at room temperature, the compounds are required to be heated in a heatable container into a liquid, and the range of the heating temperature is from room temperature to 200°C, and preferably from room temperature to 100°C.
When the mixture solution is obtained by mixing the cation precursor solution and the anion precursor solution, the cation precursor solution contains a cation source compound and at least one solvent for controlling the crystal growth of the rare earth doped fluorescent nanoparticles; said anion precursor solution contains an anion source compound and at least one solvent for dispersing the anion source compound.
The process for preparing said cation precursor solution comprises the following steps of: mixing a cation source compound and at least one solvent for controlling the crystal growth of the rare earth doped fluorescent nanoparticles, and stirring the same until the cation source compound is completely dissolved. Optionally, a low boiling point polar solvent is added therein, which aids the dissolution of said cation source compound; furthermore, a metal chelate is optionally added therein, which aids the dissolution of the cation source compound, and replaces the crystal water in the cation source compound; the low boiling point solvent is removed by distillation; the crystal water in the above-mentioned solution can either be removed or retained.
When said cation precursor is a solid or a viscous liquid at room temperature, the compounds are required to be heated in a heatable container into a liquid, and the range of the heating temperature is from room temperature to 200°C, and preferably from room temperature to 100°C. Said low boiling point polar solvent is selected from one or more of methanol, ethanol, propanol, isopropanol and butanol.
The process for preparing said anion precursor solution comprises the following steps of: mixing an anion source compound and at least one solvent for dispersing or dissolving said anion source compound, heating, and stirring the same until the formation of a transparent and homogeneous solution.
When said anion precursor is a solid or a viscous liquid at room temperature, the compounds are required to be heated in a heatable container into a liquid, and the range of the heating temperature is from room temperature to 200°C, and preferably from room temperature to 100°C.
The solvent for dispersing said anion source compound is selected from one or more of alkyl phosphate, dialkyl phosphate, trialkyl phosphate, trialkylphosphine, trialkylphosphine oxide, dihexyl ether, diphenyl ether, dibenzyl ether, dioctyl ether, dibutyl ether, dipentyl ether, diheptylether, diisoamyl ether, ethylene glycol dibutyl ether, diethylene glycol dibutyl ether, hexadecane, octadecane, icosane, tetradecane, dihexylamine, trioctylamine, di(2-ethylhexyl)amine and tri(2-ethylhexyl)amine.
Said cation precursor solution and anion precursor solution can be mixed by either traditional mixing, or mixed after being sent into a micromixer by a constant flow pump. Said constant-flow pump can be selected from HPLC pump, plunger pump, etc.
The concentration ranges of each of the substances are as follows:
In the cation precursor solution, the molar concentration of the cation source compound is 0.001 mol/L to 2.5 mol/L, preferably 0.01 mol/L to 0.7 mol/L, and more preferably 0.05 mol/L to 0.4 mol/L.
In the anion precursor solution, the molar concentration of the anion source compound is 0.001 mol/L to 2.5 mol/L, preferably 0.01 mol/L to 0.7 mol/L, and more preferably 0.05 mol/L to 0.4 mol/L.
In the mixture solution, the molar ratio of the cation source compound to the anion source compound is more than 0.5, preferably 0.5 to 10, and more preferably 0.8 to 5.
The temperature of said mixture solution is lower than the predetermined temperature of the microreactor, preferably below 200°C, and more preferably below 150°C.
The rare earth doped fluorescent nanoparticles prepared in the present invention have been extensively used in the fields such as functional films, biological labelling, solar cells, laser, high density storage, submarine communications, large screen display, detecting, and light-emitting diodes, etc.
For experimental processes that are not specified by particular conditions in the
12 following examples, the regular experimental conditions are generally followed, for example the conditions in operation manuals in catalytic chemistry, or the conditions as suggested by the manufacturers.
The pre-micro heat exchanger is a coaxial micro heat exchanger produced by Ehrfeld Mikrotechnik Bayer Technology Services GmbH, with a volume of V ~ 0.3 ml and an area of A = 0.0076 m2.
The microreactor is a sandwich micro reactor produced by Ehrfeld Mikrotechnik Bayer Technology Services GmbH, with a volume of V ~ 30 ml and an area of A ~ 0.03 m2.
The post-micro heat exchanger is a coaxial micro heat exchanger produced by Ehrfeld Mikrotechnik Bayer Technology Services GmbH, with a volume of V ~ 0.3 ml and an area of A = 0.0076 m2.
The micromixer is a valve micromixer produced by Ehrfeld Mikrotechnik Bayer Technology Services GmbH or a T mixer made in house. The valve micromixer has a length of 1000 μηι and a width of 210 μηι.
The pressure controller is selected from a pressure controller from Swagelok (USA) or a pressure controller from Ehrfeld Mikrotechnik Bayer Technology Services GmbH.
The following processes are used to characterize the rare earth doped fluorescent nanoparticles:
1) UV-vis and excitation spectrum and fluorescence spectrum
The rare earth doped fluorescent nanoparticles obtained are diluted by chloroform, and then subject to optical tests. A Specord 40 (Analytik Jena) UV-visible Spectrophotometer is used for testing the excitation spectrum of samples; and for the same solution, a Fluorolog 3-22 ( HORIBA Jobin Yvon) fluorescence spectrophotometer is used for fluorescence spectrum testing. During the measurement of fluorescence spectrum, the excitation wavelength is
277 nm.
2) Transmission electron microscopy (TEM )
A copper screen is dipped in a solution of rare earth doped fluorescent nanoparticles which have been washed in toluene, and after air drying, the transmission electron microscope photograph obtained by a CM 20 (Philips) field emission transmission electron microscope is used.
Example 1. Preparation of CePO t: Tb fluorescent nanoparticles
44 g of trioctylphosphine oxide and 48 ml of trioctylphosphine were mixed, and the mixture was heated in a container under stirring to 80°C until a transparent homogeneous solution was
13 formed. Into the above container, 22.5 mmol of CeCl3-7H20 and 7.5 mmol of TbCl3-6H20 were added, and they were stirred at 80°C until the powders were dissolved completely. At 50°C, the above solution was distilled under vacuum so as to remove water content therein; and the cation precursor solution was formed;
36 mmol of phosphoric acid, 36 ml of trioctylamine, 45 ml of 3,3' -dimethyl diphenyl ether and
40 ml of trioctylphosphine were mixed, and the mixture was stirred in another container at room temperature until a homogeneous anion precursor solution was formed;
The cation precursor solution and anion precursor solution were preheated to 60°C respectively, then sent respectively into a T micromixer by injection pumps at a certain volume flow rate (shown in Table 1) and mixed to form a mixture solution. The mixture solution was successively sent through the pre-micro heat exchanger, the microreactor, the post-micro heat exchanger and the pressure controller, and the rare earth doped fluorescent nanoparticle solution was obtained after the reaction, with the process flowchart shown in Fig. 3. The predetermined temperatures of the pre-micro heat exchanger and microreactor are shown in Table 1. The predetermined temperature of the post-micro heat exchanger was set at room temperature. The predetermined residence time of the mixture solution in the microreactor is shown in Table 1 and the pressure of the system is shown in Table 1.
The rare earth doped fluorescent nanoparticle solution was drawn from the system, and collected, to which a mixture solution of methanol and isopropanol (the volume ratio of methanol to isopropanol was 1: 10) of volume 4 times that of the solution containing rare earth doped fluorescent nanoparticles was added and mixed to form a suspension. The suspension was subjected to centrifugal sedimentation; after that the upper layer solution was removed, obtaining the rare earth doped fluorescent nanoparticle precipitates; the above washing procedure was repeated 3 times and the purified rare earth doped fluorescent nanoparticle precipitates were obtained. The rare earth doped fluorescent nanoparticle precipitates were dried in a vacuum oven at 60°C for 3 hours, and the rare earth doped fluorescent nano fluorescent particles were obtained. Table 1 shows the preparation conditions for rare earth doped fluorescent nanoparticles. Fig. 12 shows the absorption spectrum of the rare earth doped fluorescent nanoparticle sample Yl.
Table 1: Preparation conditions for CePOtiTb fluorescent nanoparticles
Figure imgf000016_0001
14 Y3 2 2 328 328 7.5 3.5
Example 2. Preparation of CePO t: Tb fluorescent nanoparticles
44 g of trioctylphosphine oxide and 73 ml of octadecene were mixed, and the mixture was heated in a container under stirring to 80°C until a transparent homogeneous solution was formed. 22.5 mmol of CeCi3-7H20 and 7.5 mmol of TbCi3-6H20 were mixed with the above solution, and distilled under vacuum at 50°C to remove water content therein, and a cation precursor solution was formed;
36 mmol of phosphoric acid, 36 ml of trioctylamine, 45 ml of 3,3' -dimethyl diphenyl ether and 60 ml of octadecene were mixed, and the mixture was stirred in another container at common temperature until a homogeneous anion precursor solution was formed;
The cation precursor solution and anion precursor solution were preheated to 60°C, and then sent respectively into a T micromixer by injection pumps at a certain volume flow rate (shown in Table 2) to form a mixture solution. The mixture solution was successively sent through the pre-micro heat exchanger, the microreactor, the post-micro heat exchanger and the pressure controller, and the rare earth doped fluorescent nanoparticle solution was obtained after the reaction. The predetermined temperatures of the pre-micro heat exchanger and microreactor were 320°C. The predetermined temperature of the post-micro heat exchanger was set at room temperature. The predetermined residence time of the mixture solution in the microreactor is shown in Table 2, with the pressure of the system being 5 bar.
The rare earth doped fluorescent nanoparticle solution was drawn from the system, and collected, to which a mixture solution of methanol and isopropanol (the volume ratio of methanol to isopropanol is 1: 10) of volume 4 times that of the solution containing rare earth doped fluorescent nanoparticles was added and mixed to form a suspension. The suspension was subjected to centrifugal sedimentation; after that the upper layer solution was removed, obtaining the rare earth doped fluorescent nanoparticle precipitates; the above washing procedure was repeated 3 times and the purified rare earth doped fluorescent nanoparticle precipitates were obtained. The rare earth doped fluorescent nanoparticle precipitates were dried in a vacuum oven at 60°C for 3 hours, and the rare earth doped fluorescent nanoparticles were obtained. Table 2 shows the preparation conditions for rare earth doped fluorescent nanoparticles. Fig. 5 shows the transmission electron microscope photograph of the rare earth doped fluorescent nanoparticle sample Y5. Fig. 12 shows the absorption spectrum of the rare earth doped fluorescent nanoparticle samples Y4 and Y5.
Table 2. Preparation conditions for CePO t:Tb fluorescent nanoparticles
Figure imgf000017_0001
15
Figure imgf000018_0001
Example 3. Preparation of CePO t: Tb fluorescent nanoparticles
44 g of trioctylphosphine oxide and 73 ml of 3,3'-dimethyl diphenyl ether were mixed, and the mixture was heated in a container under stirring to 80°C until a transparent homogeneous solution was formed. 22.5 mmol of CeCh^EhO and 7.5 mmol of TbCh-eEhO were mixed with the above solution, and distilled under vacuum at 50°C to remove water content therein, and a cation precursor solution was formed;
36 mmol of phosphoric acid, 36 ml of trioctylamine, and 72ml of 3,3' -dimethyl diphenyl ether were mixed, and the mixture was stirred in another container at common temperature until a homogeneous anion precursor solution was formed;
The cation precursor solution and anion precursor solution were preheated to 60°C, and then sent respectively into a T micromixer by injection pumps at a certain volume flow rate (shown in Table 3) to form a mixture solution. The mixture solution was successively sent through the pre-micro heat exchanger, the microreactor, the post-micro heat exchanger and the pressure controller, and the rare earth doped fluorescent nanoparticle solution was obtained after the reaction. The predetermined temperatures of the pre-micro heat exchanger and microreactor were 320°C. The predetermined temperature of the post-micro heat exchanger was set at room temperature. The predetermined residence time of the mixture solution in the microreactor is shown in Table 3, with the pressure of the system being 4 bar.
The rare earth doped fluorescent nanoparticle solution was drawn from the system, and collected, to which a mixture solution of methanol and isopropanol (the volume ratio of methanol to isopropanol is 1 : 10) of volume 4 times that of the solution containing rare earth doped fluorescent nanoparticles was added and mixed to form a suspension. The suspension was subjected to centrifugal sedimentation; after that the upper layer solution was removed, obtaining the rare earth doped fluorescent nanoparticle precipitates. The above washing procedure was repeated 3 times, and the purified rare earth doped fluorescent nanoparticle precipitates were obtained; the rare earth doped fluorescent nanoparticle precipitates were dried in a vacuum oven oven at 60°C for 3 hours, and the rare earth doped fluorescent nanoparticles were obtained. Table Table 3 shows the preparation conditions for rare earth doped fluorescent nanoparticles. Fig. Fig. 7 shows the transmission electron microscope photograph of the rare earth doped fluorescent nanoparticle sample Y8. Fig. 12 shows the absorption spectrum of the rare earth doped fluorescent nanoparticle samples Y7 and Y9.
16 Table 3. Preparation conditions for CePO tiTb fluorescent nanoparticles
Figure imgf000019_0001
Example 4. Preparation of LaPOt: Eu fluorescent nanoparticles
60g of trioctylphosphine oxide and 100 ml of octadecene were mixed, and the mixture was heated in a container under stirring to 80°C until a transparent homogeneous solution was formed. 40 mmol of LaCi3-7H20 and 2 mmol of EuCl3 were mixed with the above solution, and distilled under vacuum at 50°C to remove water content therein, and a cation precursor solution was formed;
48 mmol of phosphoric acid, 50 ml of trioctylamine, 60 ml of 3,3' -dimethyl diphenyl ether and 100 ml of octadecene were mixed, and the mixture was stirred in another container at common temperature until a homogeneous anion precursor solution was formed;
The cation precursor solution and anion precursor solution were preheated to 60°C, and then sent respectively into a T micromixer by injection pumps at a certain volume flow rate (shown in Table 4) to form a mixture solution. The mixture solution was successively sent through the pre-micro heat exchanger, the microreactor, and the post-micro heat exchanger, and the rare earth doped fluorescent nanoparticle solution was obtained after the reaction. The predetermined temperatures of the pre-micro heat exchanger and microreactor are shown in Table 4. The predetermined temperature of the post-micro heat exchanger was set at room temperature. The predetermined residence time of the mixture solution in the microreactor is shown in Table 4.
The rare earth doped fluorescent nanoparticle solution was drawn from the system, and collected, to which a mixture solution of methanol and isopropanol (the volume ratio of methanol to isopropanol is 1: 10) of volume 4 times that of the solution containing rare earth doped fluorescent nanoparticles was added and mixed to form a suspension. The suspension was subjected to centrifugal sedimentation; after that the upper layer solution was removed, obtaining the rare earth doped fluorescent nanoparticle precipitates; the above washing procedure was repeated 3 times and the purified rare earth doped fluorescent nanoparticle precipitates were were obtained. The rare earth doped fluorescent nanoparticle precipitates were dried under vacuum at 60°C for 3 hours, and the rare earth doped fluorescent nanoparticles were obtained. Table 4 shows the preparation conditions for rare earth doped fluorescent
17 nanoparticles. Fig. 7 shows the transmission electron microscope photograph of the rare earth doped fluorescent nanoparticle sample Y12. Fig. 13 shows the absorption spectrum of the rare earth doped fluorescent nanoparticle samples Y10 and Yl l .
Table 4. Preparation conditions for LaPOt: Eu fluorescent nanoparticles
Figure imgf000020_0001
Example 5. Preparation of LaPOt: Eu fluorescent nanoparticles
20 mmol of LaCi3-7H20, 1 mmol of EuCl3, 30g of trioctylphosphine oxide and 50 ml of trioctylphosphine were mixed, and the mixture was heated in a flask under stirring to 80°C until the powder was dissolved completely. At 50°C, the above solution was distilled under vacuum so as to remove water therein, and a cation precursor solution was formed;
24 mmol of phosphoric acid, 25 ml of trioctylamine, 15 ml of 3,3' -dimethyl diphenyl ether and 45 ml of trioctylphosphine were mixed, and the mixture was stirred in another container at common temperature until a homogeneous anion precursor solution was formed;
The cation precursor solution and anion precursor solution were preheated to 60°C, and sent respectively into a T micromixer by injection pumps at a certain volume flow rate (shown in Table 5) to form a mixture solution. Said mixture solution was made to flow through the microreactor and the post-micro heat exchanger and reacted at 320° C, and the rare earth doped fluorescent nanoparticle solution was obtained, with the process flowchart shown in Fig. 2. The predetermined temperature of the post-micro heat exchanger was set at room temperature, and the predetermined residence time of the mixture solution in the microreactor is shown in Table 5.
The rare earth doped fluorescent nanoparticle solution was drawn from the system, and collected, to which a mixture solution of methanol and isopropanol (the volume ratio of methanol to isopropanol is 1: 10) of volume 4 times that of the solution containing rare earth doped fluorescent nanoparticles was added and mixed to form a suspension. The suspension was subjected to centrifugal sedimentation; after that the upper layer solution was removed, obtaining the rare earth doped fluorescent nanoparticle precipitates; the above washing procedure was repeated 3 times and the purified rare earth doped fluorescent nanoparticle precipitates were
18 were obtained. The rare earth doped fluorescent nanoparticle precipitates were dried under vacuum at 60°C for 3 hours, and the rare earth doped fluorescent nanoparticles were obtained. Table 5 shows the preparation conditions for rare earth doped fluorescent nanoparticles.
Table 5. Preparation conditions for LaPO t: Eu fluorescent nanoparticles
Figure imgf000021_0001
Example 6. Preparation of LaPO t: Eu fluorescent nanoparticles
40 mmol of LaCk-TEhO, 2 mmol of EuCh, 60 g of trioctylphosphine oxide and 100 ml of 3,3' -dimethyl diphenyl ether were mixed, and the mixture was heated in a flask under stirring to 80°C until the powder was dissolved completely. At 50°C, the above solution was distilled under vacuum so as to remove water therein, and a cation precursor solution was formed.
48 mmol of phosphoric acid, 50 ml of trioctylamine, and 120 ml of 3,3' -dimethyl diphenyl ether were mixed, and the mixture was stirred in another container at common temperature until a homogeneous anion precursor solution was formed;
The cation precursor solution and anion precursor solution were preheated to 60°C, and sent respectively into a T micromixer by injection pumps at a certain volume flow rate (shown in Table 6) to form a mixture solution. Said mixture solution was made to flow through the microreactor and the post-micro heat exchanger and reacted at 300° C, and the rare earth doped fluorescent nanoparticle solution was obtained. The predetermined temperature of the post-micro heat exchanger was set at room temperature. The predetermined residence time of the mixture solution in the microreactor is shown in Table 6.
The rare earth doped fluorescent nanoparticle solution was drawn from the system, and collected, to which a mixture solution of methanol and isopropanol (the volume ratio of methanol to isopropanol is 1 : 10) of volume 4 times that of the solution containing rare earth doped fluorescent nanoparticles was added and mixed to form a suspension. The suspension was subjected to centrifugal sedimentation; after that the upper layer solution was removed, obtaining the rare earth doped fluorescent nanoparticle precipitate; the above washing procedure was repeated 3 times and the purified rare earth doped fluorescent nanoparticle precipitates were were obtained. The rare earth doped fluorescent nanoparticle precipitates were dried under vacuum at 60°C for 3 hours, and the rare earth doped fluorescent nanoparticles were obtained. Table 6 shows the preparation conditions for rare earth doped fluorescent
19 nanoparticles. The obtained LaPO t: Eu fluorescent nanoparticles were re-dispersed in chloroform solution and characterized. Figs. 8, 9 and 10 show the transmission electron microscope photographs of the rare earth doped fluorescent nanoparticle samples Y 18, Y 19 and Y20.
Table 6. Preparation conditions for LaPO t: Eu fluorescent nanoparticles
Figure imgf000022_0001
Example 7. Preparation of LaPO t: Eu fluorescent nanoparticles
82 ml of octadecene, 45 g of trioctylphosphine oxide, 30 mmol of LaCh^E O and 1.5 mmol of EuCh, together with 40 mmol of LaCh^EhO, 2 mmol of EuCh, 60 g of trioctyl phosphine oxide, and 100 ml of 3,3'-dimethyl diphenyl ether were mixed, and the mixture was heated in a flask under stirring to 80°C until the powder was dissolved completely. At 50°C, the above solution was distilled under vacuum so as to remove water therein; and a cation precursor solution was formed;
36 mmol of phosphoric acid, 36 ml of trioctylamine, 45 ml of 3,3' -dimethyl diphenyl ether and 90 ml of octadecene were mixed, and the mixture was stirred in another container at common temperature until a homogeneous anion precursor solution was formed;
The cation precursor solution and anion precursor solution were preheated to 60°C, and sent respectively into a T micromixer by injection pumps at a volume flow rate of 1 ml/min to form a mixture solution. Said mixture solution was made to flow through the microreactor and the post- micro heat exchanger and reacted at 300° C, and the rare earth doped fluorescent nanoparticle solution was obtained. The predetermined temperature of the post-micro heat exchanger was set at room temperature. The predetermined residence time of the mixture solution in the microreactor was 15 min.
The rare earth doped fluorescent nanoparticle solution was drawn from the system, and collected, to which a mixture solution of methanol and isopropanol (the volume ratio of methanol to isopropanol is 1 : 10) of 4 times of that of the solution containing rare earth doped fluorescent nanoparticles was added and mixed to form a suspension. The suspension was subjected to centrifugal sedimentation; after that the upper layer solution was removed, obtaining the rare earth doped fluorescent nanoparticle precipitate; the above washing procedure was
20 repeated 3 times and the purified rare earth doped fluorescent nanoparticle precipitates were were obtained. The rare earth doped fluorescent nanoparticle precipitates were dried under vacuum at 60°C for 3 hours, and the rare earth doped fluorescent nanoparticles were obtained.
Example 8. Preparation of CePOt: Tb fluorescent nanoparticles
5 ml of methanol, 3.75 mmol of CeCl3- 7H20 and 1.25 mmol of TbCl3- 6H20 were mixed, and the mixture was heated in a flask under stirring to 80°C, until the powder was dissolved completely. 40 ml trioctylphosphine and 8.5 g trioctylphosphine oxide were mixed with the above solution, heated to 80°C, and stirred for 30 min, until a homogeneous solution was formed. It was distilled at 50°C under vacuum to remove water and methanol therein, then 50 ml of dibenzyl ether was added therein, and the cation precursor solution was formed;
11 mmol of phosphoric acid, 11 ml of trioctylamine, 89 ml of dibenzyl ether and 9 ml of trioctyl phosphine oxide were mixed, and the mixture was stirred in another container at common temperature until a homogeneous anion precursor solution was formed;
The cation precursor solution and anion precursor solution were preheated to 80°C, and sent respectively into a T micromixer by injection pumps at a certain volume flow rate (shown in Table 7) to form a mixture solution. Said mixture solution was made to flow through the microreactor and the post-micro heat exchanger and reacted at 320°C, and the rare earth doped fluorescent nanoparticle solution was obtained. The predetermined temperature of the post-micro heat exchanger was set at room temperature, and the predetermined residence time of the mixture solution in the microreactor is shown in Table 7.
The rare earth doped fluorescent nanoparticle solution was drawn from the system, and collected, to which a mixture solution of methanol and isopropanol (the volume ratio of methanol to isopropanol is 1: 10) of volume 4 times that of the solution containing rare earth doped fluorescent nanoparticles was added and mixed to form a suspension. The suspension was centrifugal sedimentation; the upper layer solution after centrifuging and settling was removed, and the rare earth doped fluorescent nanoparticle precipitates were obtained; the above washing procedure was repeated 3 times; and the purified rare earth doped fluorescent nanoparticle precipitates were obtained. The rare earth doped fluorescent nanoparticle precipitates were dried under vacuum at 60°C for 4 hours, and the rare earth doped fluorescent nanoparticles were obtained. Table 7 shows the preparation conditions for rare earth doped fluorescent nanoparticles.
Table 7. Preparation conditions for CePOt:Tb fluorescent nanoparticles
21 Flow rate of the cation Flow rate of the anion Residence time inside
Sample No. precursor solution precursor solution the microreactor
(ml/min) (ml/min) (min)
Y 22 0.5 0.5 30
Y 23 1 1 15
Y 24 2 2 7.5
Y 25 5 5 3
Example 9. Preparation of LaPOt: Eu fluorescent nanoparticles
20 ml of methanol, 20 mmol of LaCl3- 7H20 and 1 mmol of EuC were mixed, and the mixture was heated in a container under stirring to 60°C, until the powder was dissolved completely. 22 ml of tributyl phosphate, and 60 ml dibenzyl ether were mixed in the above container, stirred at 80°C for 30 min, until a homogeneous solution was formed. At 50°C, the above solution was distilled under vacuum so as to remove water therein; and the cation precursor solution was formed;
22 mmol of phosphoric acid, 20 ml of trioctylamine, and 60 ml of dibenzyl ether were mixed, and the mixture was stirred in another container at common temperature until a homogeneous anion precursor solution was formed;
The cation precursor solution and anion precursor solution were preheated to 80°C, and sent respectively into a T micromixer by injection pumps at a certain volume flow rate (shown in Table 8) to form a mixture solution. Said mixture solution was made to flow through the microreactor and the post-micro heat exchanger and reacted at the predetermined temperature of said micro heat exchanger (shown in Table 8), and the rare earth doped fluorescent nanoparticle solution was obtained. The predetermined temperature of the post-micro heat exchanger was set at room temperature, and the predetermined residence time of the mixture solution in the microreactor is shown in Table 8.
The rare earth doped fluorescent nanoparticle solution was drawn from the system, and collected, to which a mixture solution of methanol and isopropanol (the volume ratio of methanol to isopropanol is 1: 10) of volume 4 times that of the solution containing rare earth doped fluorescent nanoparticles was added and mixed to form a suspension. The suspension was subjected to centrifugal sedimentation; after that the upper layer solution was removed, obtaining the rare earth doped fluorescent nanoparticle precipitates; the above washing procedure was repeated 4 times and the purified rare earth doped fluorescent nanoparticle precipitates were were obtained. The rare earth doped fluorescent nanoparticle precipitates were dried under vacuum at 60°C for 4 hours, and the rare earth doped fluorescent nanoparticles were
22 obtained. Table 8 shows the preparation conditions for rare earth doped fluorescent nanoparticles.
Table 8. Preparation conditions for LaPOt: Eu fluorescent nanoparticles
Figure imgf000025_0001
Example 10. Preparation of LaPOt: Eu fluorescent nanoparticles
10 ml of methanol, 20 mmol of LaCl3-7H20 and 0.5 mmol of EuCl3 were mixed, and the mixture was heated in a flask under stirring to 60°C, until the powder was dissolved completely. 40 ml trioctylphosphine and 10 g trioctylphosphine oxide were mixed with the above solution, heated to 80°C, and stirred for 30 min, until a homogeneous solution was formed. It was distilled at 50°C under vacuum to remove water and methanol therein, and a cation precursor solution was formed;
11 mmol of phosphoric acid, 11 ml of trioctylamine, and 89 ml of dibenzyl ether were mixed, and the mixture was stirred in another container at common temperature until a homogeneous anion precursor solution was formed;
The cation precursor solution and anion precursor solution were preheated to 80°C, and sent into a T micromixer by injection pumps at respective volume flow rates of 0.5 ml/min, and 0.5 ml/min to form a mixture solution. The mixture solution was sent through the pre-micro heat exchanger, the microreactor, the post-micro heat exchanger and the pressure controller, and the rare earth doped fluorescent nanoparticle solution was obtained after the reaction. The predetermined temperature of the pre-micro heat exchanger, the microreactor and the post-micro heat exchanger was set at 320°C, 300°C and 30°C, respectively. The predetermined residence time of the mixture solution in the microreactor was 30 min. The pressure of the system was 3 bar.
The methanol and isopropanol mixture (the volume ratio of methanol to isopropyl is 1 : 10) was sent by an HPLC pump at a flow rate of 4 ml/min, and mixed with the rare earth doped fluorescent nanoparticle solution in a valve micromixer, and a suspension was formed. The suspension was subjected to centrifugal sedimentation; after that the upper layer solution was removed, obtaining the rare earth doped fluorescent nanoparticle precipitates. The above washing procedure was repeated 3 times, and the purified rare earth doped fluorescent
23 nanoparticle precipitates were obtained; the rare earth doped fluorescent nanoparticle precipitates were dried in a vacuum oven at 60°C for 4 hours, and the rod-shaped rare earth doped fluorescent nano fluorescent particle precipitates were obtained. Fig. 14 shows the transmission electron microscope photograph of the rare earth doped fluorescent nanoparticles obtained in this example.
Example 11. Preparation of NaYFt: Yb: Er fluorescent nanoparticles
19.4 mmol of Y2O3, 10 mmol of YI52O3, 1 mmol of ΕΓ2<¾, 80 ml of deionized water and 120 ml of trifluoroacetic acid were mixed, and the mixture was heated in a flask to the refluxing temperature of the solution under stirring, until a homogeneous solution was formed. The excess water and trifluoroacetic acid in the above solution were removed under vacuum by distillation at 100°C, and the dried mixed powder was obtained. Into the above flask, 100 mmol of sodium trifluoroacetate and 240 ml of oleylamine were added and heated to 100°C and stirred for 30 min under vacuum to form a solution; trace amounts of water and oxygen in the solution were removed; and the mixture was stirred in a nitrogen atmosphere until a homogeneous solution was formed.
The solution was sent into the T micromixer at a certain flow rate (shown in Table 9) by a high performance liquid chromatogram pump, and a mixture solution was formed. The mixture solution was sent through the pre-micro heat exchanger, the microreactor, and the post-micro heat exchanger, and the rare earth doped fluorescent nanoparticle solution was obtained after the reaction. The predetermined temperatures of pre-micro heat exchanger and microreactor are shown in Table 9. The predetermined temperature of the post-micro heat exchanger was set at room temperature. The predetermined residence time of the mixture solution in the microreactor was 15 min.
The rare earth doped fluorescent nanoparticle solution was drawn from the system, and collected, to which a mixture solution of methanol and cyclohexane (the volume ratio of methanol to cyclohexane is 9: 1) of volume 4 times that of the solution containing rare earth doped fluorescent nanoparticles was added and mixed to form a suspension. The suspension was subjected to centrifugal sedimentation; after that the upper layer solution was removed, obtaining the rare earth doped fluorescent nanoparticle precipitates. The above precipitates were then washed 3 times with a mixture solution of methanol and isopropanol of 3 times the volume (the volume ratio is 9 : 1), and the purified rare earth doped fluorescent nanoparticle precipitates were obtained; the rare earth doped fluorescent nanoparticle precipitates were dried in a vacuum oven at 60°C for 2 hours, and the rare earth doped fluorescent nanoparticles were obtained. Table 9 shows the preparation conditions for rare earth doped fluorescent nanoparticles. Fig. 1 1 shows the transmission electron microscope photograph of the rare earth doped fluorescent nanoparticle sample Y31.
Table 9. Preparation conditions for NaYFt: Yb: Er fluorescent nanoparticles
24
Figure imgf000027_0001
Example 12. Preparation of LaPO t: Ce: Dy fluorescent nanoparticles
12 ml of methanol, 8.9 mmol of LaCl3- 7H20, 1 mmol of CeCl3-7H20, 10 ml of trioctylphosphine, 8.33 g of trioctylphosphine oxide and 0.1 mmol of DyCl3 were mixed, and the mixture was heated in a flask under stirring to 60°C until the powder was dissolved completely. Water and methanol in the above solution were removed by vacuum distillation at 50°C; 10 mmol phosphoric acid and 82 ml of trioctylphosphine oxide were added into the above solution, and stirred until a homogeneous transparent solution was formed.
The above mixture solution was subsequently sent through the pre-micro heat exchanger and the microreactor at a volume flow rate of 1 ml/min at common temperature, and the rare earth doped fluorescent nanoparticle solution was obtained after the reaction. The predetermined temperature of the pre-micro heat exchanger was 340°C, and the predetermined temperature of the microreactor was 300°C. The predetermined residence time of the mixture solution in the microreactor was 30 min.
The rare earth doped fluorescent nanoparticle solution was drawn from the system, collected, and cooled naturally, to which a mixture solution of methanol and isopropanol (the volume ratio of methanol to isopropanol is 1 : 10) of volume 4 times that of the solution containing rare earth doped fluorescent nanoparticles was added and mixed to form a suspension. The suspension was subjected to centrifugal sedimentation, the upper layer solution after centrifuging and settling was removed, and the rare earth doped fluorescent nanoparticle precipitates were obtained. The above washing procedure was repeated 4 times, and the purified rare earth doped fluorescent nanoparticle precipitates were obtained. The rare earth doped fluorescent nanoparticle precipitates were dried under vacuum at 60°C for 4 hours, and the rare earth doped fluorescent nanoparticles were obtained.
Example 13. Preparation of LaB03: Ce: Dy fluorescent nanoparticles
4 ml of methanol, 35.6 mmol of LaCl3- 7H20, 4 mmol of CeCl3-7H20, 0.4 mmol of DyCl3, 45 ml of trioctyl phosphate and 125 ml of diphenyl ether were mixed, and the mixture was heated in a flask under stirring to 50°C until the powder was dissolved completely. Water and methanol in the above solution were removed by vacuum distillation at 50°C; 40 mmol of
25 phosphoric acid, 30 ml of dihexyl ether and 42 ml of trihexylamine were added into the above solution and stirred, until a homogeneous solution was formed.
The above mixture solution was subsequently sent through the pre-micro heat exchanger, the microreactor, and the pressure controller at a volume flow rate of 5 ml/min at common temperature, and the rare earth doped fluorescent nanoparticle solution was obtained after the reaction. The predetermined temperature of the pre-micro heat exchanger was 340°C, and the predetermined temperature of the microreactor was set as 300°C, with the system pressure being 5 bar. The predetermined residence time of the mixture solution in the microreactor was 6 min.
The rare earth doped fluorescent nanoparticle solution was drawn from the system, collected, and cooled naturally, to which a mixture solution of methanol and isopropanol (the volume ratio of methanol to isopropanol is 1 : 10) of volume 4 times that of the solution containing rare earth doped fluorescent nanoparticles was added and mixed to form a suspension. The suspension was subjected to centrifugal sedimentation; after that the upper layer solution was removed, obtaining the rare earth doped fluorescent nanoparticle precipitates. The above washing procedure was repeated 4 times, and the purified rare earth doped fluorescent nanoparticle precipitates were obtained. The rare earth doped fluorescent nanoparticle precipitates were dried under vacuum at 60°C for 4 hours, and the rare earth doped fluorescent nanoparticles were obtained. Example 14. Preparation of CePO t: Tb fluorescent nanoparticles
10 ml of methanol, 22.5 mmol of CeCl3-7H20, 7.5 mmol of TbCl3-6H20, 30 ml of dimethyl phenyl ether, and 11 ml of trioctyl phosphate were mixed, and the mixture was heated in a flask under stirring to 50°C until the powder was dissolved completely. Methanol in the above solution was removed by vacuum distillation at room temperature; 30 mmol of phosphoric acid and 11 ml of trihexylamine were added into the above solution and stirred, until a homogeneous solution was formed.
The above mixture solution was preheated to 60°C, and subsequently sent through the pre-micro heat exchanger, the microreactor, and the post-micro heat exchanger at a volume flow rate of 1 ml/min, and the rare earth doped fluorescent nanoparticle solution was obtained after the reaction. The predetermined temperature of the pre-micro heat exchanger, the microreactor and the post-micro heat exchanger was set at 300°C, 280°C and 25°C respectively, with the system pressure being 5 bar. The predetermined residence time of the mixture solution in the microreactor was 30 min.
The methanol and isopropanol mixture (the volume ratio of methanol to isopropyl is 1 : 10) was sent by a high performance liquid chromatograph pump at a flow rate of 4 ml/min, and mixed with the rare earth doped fluorescent nanoparticle solution in a valve micromixer, and a suspension
26 was formed. The suspension was subjected to centrifugal sedimentation; after that the upper layer solution was removed, obtaining the rare earth doped fluorescent nanoparticle precipitates. The above washing procedure was repeated 3 times, and the purified rare earth doped fluorescent nanoparticle precipitates were obtained; the rare earth doped fluorescent nanoparticle precipitates were dried in a vacuum oven at 60°C for 3 hours, and the rod-shaped rare earth doped fluorescent nano fluorescent particle precipitates were obtained. Fig. 14 shows the transmission electron microscope photograph of the rare earth doped fluorescent nanoparticles obtained in this example.
27

Claims

Claims
1. Process for continuously preparing a rare earth doped fluorescent nanoparticle solution, comprising the following steps of:
mixing a cation source compound, an anion source compound, and at least one solvent for controlling the crystal growth of said rare earth doped fluorescent nanoparticles to form a mixture solution; and
maintaining said mixture solution in a microreactor for a predetermined period of time at a predetermined temperature, so as to obtain said rare earth doped fluorescent nanoparticle solution, wherein said microreactor comprises a micromixing device and a micro heat exchanging device, with said micromixing device being for continuously mixing said mixture solution, and said micro heat exchanging device being for adjusting the temperature of said microreactor to said predetermined temperature.
2. Preparation process according to Claim 1, further comprising a step of: controlling the pressure of said microreactor, so as to maintain the rare earth doped fluorescent nanoparticle solution in a liquid phase.
3. Preparation process according to Claim 1 or 2, wherein said rare earth doped fluorescent nanoparticles are selected from one of:
LnP04: Ce: W,
LnP04: Eu,
LnV04: Ce: W,
LnV04: Eu,
Ln(V04)x(P04)y: B (x + y = 1, wherein 0 < x < 1),
AYF4: G,
AYCU: G,
AYBr : G,
NaQF4: Yb: B,
NaQCl4: Yb: B,
NaQBr4: Yb: B,
LnB03: Ce: W,
LnB03: Eu,
(YGd)B03: Eu,
DS0 : B,
28 DS04: Mn, and
Zn2(Si04): Mn;
wherein Ln represents a lanthanide element, Y or Sc; D represents Ba, Sr or Ca; E represents Cu, Ag, Eu, Bi, Al or Au; G represents Pr, Tm, Er, Yb or Ho; Q represents Gd, Y, Li or K; W represents Tb or Dy; A is selected from one or more of Li, Na, K, Rb, Mgo.5, Bao.5, Cao.5 and Sro.5; and B represents a lanthanide element.
4. Preparation process according to Claim 1 or 2, wherein the predetermined temperature of said microreactor is above 200°C.
5. Preparation process according to Claim 1 or 2, wherein the predetermined residence time in said microreactor is 30s to 7200s.
6. Preparation process according to Claim 1 or 2, wherein at the front end of said microreactor, at least one pre-micro heat exchanger is installed, and said pre-micro heat exchanger is used for heating said mixture solution.
7. Preparation process according to Claim 1 or 2, wherein at the rear end of said microreactor, at least one post-micro heat exchanger is installed, and said post-micro heat exchanger is used for cooling said rare earth doped fluorescent nanoparticle solution.
8. Preparation process according to Claim 1 or 2, wherein said mixture solution comprises water so as to obtain rod-shaped rare earth doped fluorescent nanoparticles, and said water either comes from the cation source compound or is added therein directly.
9. Process for continuously preparing rare earth doped fluorescent nanoparticles, comprising the following steps of:
mixing the rare earth doped fluorescent nanoparticle solution prepared by the process according to any of Claims 1 to 8 with a polar solvent, so as to form a suspension; and separating said suspension to obtain the rare earth doped fluorescent nanoparticles.
10. System for continuously preparing a rare earth doped fluorescent nanoparticle solution, said system comprising:
a mixer for mixing a cation source compound, an anion source compound, and at least one solvent for controlling the crystal growth of said rare earth doped fluorescent
29 nanoparticles to form a mixture solution;
a pre-micro heat exchanger for heating said mixture solution;
at least one microreactor for maintaining said mixture solution for a predetermined period of time at a predetermined temperature, so as to obtain said rare earth doped fluorescent nanoparticle solution, wherein said microreactor comprises a micromixing device and a micro heat exchanging device, with said micromixing device being used for continuously mixing said mixture solution, and said micro heat exchanging device being used for adjusting the temperature of said microreactor to said predetermined temperature; a post-micro heat exchanger for cooling said rare earth doped fluorescent nanoparticle solution; and
a pressure controller for controlling the pressure of said system, so as to maintain the mixture solution and said rare earth doped fluorescent nanoparticle solution in a liquid phase.
11. System for continuously preparing rare earth doped fluorescent nanoparticles, said system comprising:
a mixer for mixing a cation source compound, an anion source compound, and at least one solvent for controlling the crystal growth of said rare earth doped fluorescent nanoparticles to form a mixture solution;
a pre-micro heat exchanger for heating said mixture solution;
at least one microreactor for maintaining said mixture solution for a predetermined period of time at a predetermined temperature, so as to obtain a rare earth doped fluorescent nanoparticle solution, wherein said microreactor comprises a micromixing device and a micro heat exchanging device, with said micromixing device being used for continuously mixing said mixture solution, and said micro heat exchanging device being used for adjusting the temperature of said microreactor to said predetermined temperature; a post-micro heat exchanger for cooling said rare earth doped fluorescent nanoparticle solution;
a pressure controller for controlling the pressure of said system, so as to maintain the mixture solution and said rare earth doped fluorescent nanoparticle solution in a liquid phase;
a mixing device for mixing said rare earth doped fluorescent nanoparticle solution and a polar solvent to form a suspension; and
a separating device for separating said suspension, so as to obtain said rare earth doped fluorescent nanoparticles.
30
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