CN107880873B - Preparation method of zinc oxide-barium sulfate composite nanomaterial, application of zinc oxide-barium sulfate composite nanomaterial and LED chip - Google Patents
Preparation method of zinc oxide-barium sulfate composite nanomaterial, application of zinc oxide-barium sulfate composite nanomaterial and LED chip Download PDFInfo
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- CN107880873B CN107880873B CN201711076666.5A CN201711076666A CN107880873B CN 107880873 B CN107880873 B CN 107880873B CN 201711076666 A CN201711076666 A CN 201711076666A CN 107880873 B CN107880873 B CN 107880873B
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- 239000002131 composite material Substances 0.000 title claims abstract description 101
- 239000002086 nanomaterial Substances 0.000 title claims abstract description 96
- BLEUEDZLGUTZDW-UHFFFAOYSA-L zinc barium(2+) oxygen(2-) sulfate Chemical compound [O-2].[Zn+2].[Ba+2].[O-]S([O-])(=O)=O BLEUEDZLGUTZDW-UHFFFAOYSA-L 0.000 title claims abstract description 90
- 238000002360 preparation method Methods 0.000 title claims abstract description 28
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 claims abstract description 293
- 239000011787 zinc oxide Substances 0.000 claims abstract description 124
- 239000000243 solution Substances 0.000 claims abstract description 93
- 239000002244 precipitate Substances 0.000 claims abstract description 56
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 41
- 238000000034 method Methods 0.000 claims abstract description 29
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 claims abstract description 19
- 159000000009 barium salts Chemical class 0.000 claims abstract description 15
- 230000004048 modification Effects 0.000 claims abstract description 14
- 238000012986 modification Methods 0.000 claims abstract description 14
- 239000012266 salt solution Substances 0.000 claims abstract description 13
- 239000011258 core-shell material Substances 0.000 claims abstract description 10
- 238000002156 mixing Methods 0.000 claims abstract description 9
- 238000003980 solgel method Methods 0.000 claims abstract description 7
- TZCXTZWJZNENPQ-UHFFFAOYSA-L barium sulfate Inorganic materials [Ba+2].[O-]S([O-])(=O)=O TZCXTZWJZNENPQ-UHFFFAOYSA-L 0.000 claims description 42
- 238000001035 drying Methods 0.000 claims description 26
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 claims description 24
- 239000006087 Silane Coupling Agent Substances 0.000 claims description 22
- WYTZZXDRDKSJID-UHFFFAOYSA-N (3-aminopropyl)triethoxysilane Chemical compound CCO[Si](OCC)(OCC)CCCN WYTZZXDRDKSJID-UHFFFAOYSA-N 0.000 claims description 20
- 229910001422 barium ion Inorganic materials 0.000 claims description 20
- 239000002585 base Substances 0.000 claims description 19
- 239000000463 material Substances 0.000 claims description 17
- 150000003751 zinc Chemical class 0.000 claims description 16
- WMFOQBRAJBCJND-UHFFFAOYSA-M Lithium hydroxide Chemical compound [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 0.000 claims description 15
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 15
- 150000008044 alkali metal hydroxides Chemical class 0.000 claims description 15
- 239000011259 mixed solution Substances 0.000 claims description 12
- WDIHJSXYQDMJHN-UHFFFAOYSA-L barium chloride Chemical compound [Cl-].[Cl-].[Ba+2] WDIHJSXYQDMJHN-UHFFFAOYSA-L 0.000 claims description 11
- 229910001626 barium chloride Inorganic materials 0.000 claims description 11
- CSNNHWWHGAXBCP-UHFFFAOYSA-L Magnesium sulfate Chemical compound [Mg+2].[O-][S+2]([O-])([O-])[O-] CSNNHWWHGAXBCP-UHFFFAOYSA-L 0.000 claims description 10
- ZOIORXHNWRGPMV-UHFFFAOYSA-N acetic acid;zinc Chemical compound [Zn].CC(O)=O.CC(O)=O ZOIORXHNWRGPMV-UHFFFAOYSA-N 0.000 claims description 10
- 239000004246 zinc acetate Substances 0.000 claims description 10
- ONDPHDOFVYQSGI-UHFFFAOYSA-N zinc nitrate Chemical compound [Zn+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O ONDPHDOFVYQSGI-UHFFFAOYSA-N 0.000 claims description 10
- XDFCIPNJCBUZJN-UHFFFAOYSA-N barium(2+) Chemical compound [Ba+2] XDFCIPNJCBUZJN-UHFFFAOYSA-N 0.000 claims description 9
- 239000006185 dispersion Substances 0.000 claims description 9
- 238000005406 washing Methods 0.000 claims description 9
- JIAARYAFYJHUJI-UHFFFAOYSA-L zinc dichloride Chemical compound [Cl-].[Cl-].[Zn+2] JIAARYAFYJHUJI-UHFFFAOYSA-L 0.000 claims description 8
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 claims description 7
- 229910052783 alkali metal Inorganic materials 0.000 claims description 7
- 150000001340 alkali metals Chemical group 0.000 claims description 7
- IDGUHHHQCWSQLU-UHFFFAOYSA-N ethanol;hydrate Chemical compound O.CCO IDGUHHHQCWSQLU-UHFFFAOYSA-N 0.000 claims description 7
- 229910052938 sodium sulfate Inorganic materials 0.000 claims description 7
- 235000011152 sodium sulphate Nutrition 0.000 claims description 7
- IWOUKMZUPDVPGQ-UHFFFAOYSA-N barium nitrate Chemical compound [Ba+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O IWOUKMZUPDVPGQ-UHFFFAOYSA-N 0.000 claims description 6
- 238000010438 heat treatment Methods 0.000 claims description 5
- 229910052943 magnesium sulfate Inorganic materials 0.000 claims description 5
- 235000019341 magnesium sulphate Nutrition 0.000 claims description 5
- OTYBMLCTZGSZBG-UHFFFAOYSA-L potassium sulfate Chemical compound [K+].[K+].[O-]S([O-])(=O)=O OTYBMLCTZGSZBG-UHFFFAOYSA-L 0.000 claims description 5
- 229910052939 potassium sulfate Inorganic materials 0.000 claims description 5
- 235000011151 potassium sulphates Nutrition 0.000 claims description 5
- LMDAGMAWWYVRJZ-UHFFFAOYSA-N ethanol;zinc Chemical compound [Zn].CCO LMDAGMAWWYVRJZ-UHFFFAOYSA-N 0.000 claims description 4
- 239000011592 zinc chloride Substances 0.000 claims description 4
- 235000005074 zinc chloride Nutrition 0.000 claims description 4
- NWONKYPBYAMBJT-UHFFFAOYSA-L zinc sulfate Chemical compound [Zn+2].[O-]S([O-])(=O)=O NWONKYPBYAMBJT-UHFFFAOYSA-L 0.000 claims description 4
- 229960001763 zinc sulfate Drugs 0.000 claims description 4
- 229910000368 zinc sulfate Inorganic materials 0.000 claims description 4
- DIZPMCHEQGEION-UHFFFAOYSA-H aluminium sulfate (anhydrous) Chemical compound [Al+3].[Al+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O DIZPMCHEQGEION-UHFFFAOYSA-H 0.000 claims description 3
- 150000003467 sulfuric acid derivatives Chemical class 0.000 claims description 2
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims 1
- 235000011114 ammonium hydroxide Nutrition 0.000 claims 1
- 239000000843 powder Substances 0.000 abstract description 28
- 239000002253 acid Substances 0.000 abstract description 4
- 239000003513 alkali Substances 0.000 abstract description 3
- 239000003960 organic solvent Substances 0.000 abstract description 3
- 238000003756 stirring Methods 0.000 description 22
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 18
- 230000000052 comparative effect Effects 0.000 description 10
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 9
- 239000007822 coupling agent Substances 0.000 description 8
- 230000008859 change Effects 0.000 description 7
- 239000002105 nanoparticle Substances 0.000 description 7
- 238000012360 testing method Methods 0.000 description 6
- 238000000137 annealing Methods 0.000 description 5
- 239000002245 particle Substances 0.000 description 5
- 239000002994 raw material Substances 0.000 description 5
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical group N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 238000004020 luminiscence type Methods 0.000 description 4
- 239000003607 modifier Substances 0.000 description 4
- 230000002776 aggregation Effects 0.000 description 3
- 239000013078 crystal Substances 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 238000000024 high-resolution transmission electron micrograph Methods 0.000 description 3
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 3
- 239000002096 quantum dot Substances 0.000 description 3
- 230000000171 quenching effect Effects 0.000 description 3
- 230000005855 radiation Effects 0.000 description 3
- 229910052761 rare earth metal Inorganic materials 0.000 description 3
- 150000002910 rare earth metals Chemical class 0.000 description 3
- 239000004065 semiconductor Substances 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- 241000219991 Lythraceae Species 0.000 description 2
- 235000014360 Punica granatum Nutrition 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 238000003917 TEM image Methods 0.000 description 2
- 238000004220 aggregation Methods 0.000 description 2
- -1 alkoxide compounds Chemical class 0.000 description 2
- 229910021529 ammonia Inorganic materials 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 2
- 239000007864 aqueous solution Substances 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 238000000635 electron micrograph Methods 0.000 description 2
- 238000002189 fluorescence spectrum Methods 0.000 description 2
- 238000005286 illumination Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 239000002114 nanocomposite Substances 0.000 description 2
- 239000002243 precursor Substances 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 239000011241 protective layer Substances 0.000 description 2
- 238000010791 quenching Methods 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 238000002791 soaking Methods 0.000 description 2
- 238000000527 sonication Methods 0.000 description 2
- 238000001179 sorption measurement Methods 0.000 description 2
- 241000283690 Bos taurus Species 0.000 description 1
- 241001083505 Punica Species 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 150000007513 acids Chemical class 0.000 description 1
- 238000005054 agglomeration Methods 0.000 description 1
- 230000002238 attenuated effect Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
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- 238000004140 cleaning Methods 0.000 description 1
- 239000003086 colorant Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000011049 filling Methods 0.000 description 1
- 229910001385 heavy metal Inorganic materials 0.000 description 1
- 150000002484 inorganic compounds Chemical class 0.000 description 1
- 229910010272 inorganic material Inorganic materials 0.000 description 1
- 238000011031 large-scale manufacturing process Methods 0.000 description 1
- 239000010410 layer Substances 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 238000005065 mining Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 150000007530 organic bases Chemical class 0.000 description 1
- 150000002902 organometallic compounds Chemical class 0.000 description 1
- 239000008188 pellet Substances 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 125000002924 primary amino group Chemical group [H]N([H])* 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
- 239000002689 soil Substances 0.000 description 1
- 238000013112 stability test Methods 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
- DLISVLVFJRCVJM-UHFFFAOYSA-N zinc oxygen(2-) phosphane Chemical compound [O--].P.[Zn++] DLISVLVFJRCVJM-UHFFFAOYSA-N 0.000 description 1
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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
- C09K11/54—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing zinc or cadmium
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- 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
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- C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
- C09K11/02—Use of particular materials as binders, particle coatings or suspension media therefor
- C09K11/025—Use of particular materials as binders, particle coatings or suspension media therefor non-luminescent particle coatings or suspension media
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L33/48—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor body packages
- H01L33/50—Wavelength conversion elements
- H01L33/501—Wavelength conversion elements characterised by the materials, e.g. binder
- H01L33/502—Wavelength conversion materials
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Abstract
The invention discloses a preparation method of a zinc oxide-barium sulfate composite nano material, the zinc oxide-barium sulfate composite nano material, application and an LED chip, and relates to the technical field of zinc oxide fluorescent powder. The method comprises the following steps: (a) preparing nano zinc oxide by adopting a sol-gel method, and carrying out surface modification on the nano zinc oxide to obtain zinc oxide powder; (b) dissolving zinc oxide powder in water to obtain a zinc oxide solution, adding a sulfate solution into the zinc oxide solution, uniformly mixing, adding a barium salt solution, and forming a precipitate to obtain the zinc oxide-barium sulfate composite nano material. The invention relieves the problems of poor stability, serious light decay, poor thermal stability, no acid, alkali and various organic solvents of nano zinc oxide and little application of nano zinc oxide to LED fluorescent powder, and the pomegranate-shaped multi-core-shell ZnO-BaSO obtained by the method of the invention4The composite nano material has high light stability, pH stability and thermal stability.
Description
Technical Field
The invention relates to the technical field of zinc oxide fluorescent powder, and particularly relates to a preparation method of a zinc oxide-barium sulfate composite nano material, the zinc oxide-barium sulfate composite nano material, application and an LED chip.
Background
In recent years, Light Emitting Devices (LEDs) have been widely studied because of their advantages of low power consumption, long life, multiple emission colors, high efficiency, and the like. Up to now, commercial white LEDs are generally implemented by coating a phosphor on a blue LED chip or a luminescent phosphor on an Ultraviolet (UV) chip, and a high-power UV chip generates much heat when it is operated, and the heat causes a decrease in luminous efficiency of the phosphor.
The LED chip and the phosphor determine the performance of the Light Emitting Diode (LED). The conventional fluorescent powder mainly comprises rare earth fluorescent powder, semiconductor quantum dot fluorescent powder or carbon-based fluorescent powder. These phosphors have some limitations and disadvantages:
(1) rare earth fluorescent powder: rare earths are non-renewable resources and the mining and purification of rare earth ores involves complex operations and expensive costs.
(2) Semiconductor quantum dot phosphor: the main semiconductor-based phosphor is Cd2+The basic quantum dots, which are heavy metals, can contaminate water sources and soil, and are harmful to the body.
(3) Carbon-based phosphor: due to the agglomeration quenching effect of the carbon quantum dots, the fluorescence efficiency of the carbon dots is greatly reduced when the carbon dots are prepared into powder. Is not suitable for large-scale production.
Therefore, the development of efficient, environmentally friendly, large-scale-producible and low-cost phosphors remains a challenge and is of great significance for the application of commercial Light Emitting Devices (LEDs).
Zinc oxide is rarely used in LED phosphors because of its poor stability, severe light decay, poor thermal stability, and resistance to acids, bases, and various organic solvents.
In view of the above, the present invention is particularly proposed.
Disclosure of Invention
The invention aims to provide a preparation method of a zinc oxide-barium sulfate composite nano material, which comprises the steps of firstly obtaining surface modified nano ZnO, dissolving the ZnO in water, keeping electrostatic balance, adding SO4 2-Then, the electrostatic balance is broken, ZnO is gathered into multi-ZnO nuclear luminescent centers, and then Ba is added2+Then, BaSO4The shell grows around the surface of the luminescent center to form pomegranate-shaped multi-core-shell ZnO-BaSO4Composite nanomaterial of BaSO4The protection of the shell gives the inner ZnO excellent photostability and thermal stability.
The second purpose of the invention is to provide the zinc oxide-barium sulfate composite nano material prepared by the preparation method of the zinc oxide-barium sulfate composite nano material, the structure of the composite material is similar to a pomegranate-shaped structure, ZnO is used as an internal seed, and BaSO is used as an internal seed4As seed coat, due to BaSO4The protection of the shell enables the ZnO in the shell to have excellent light stability and thermal stability, and the mixed fluorescent powder with high light stability, high pH stability and high thermal stability is realized.
The invention also aims to provide application of the zinc oxide-barium sulfate composite nano material in preparation of a light-emitting device.
The fourth purpose of the invention is to provide an LED chip coated with the zinc oxide-barium sulfate composite nano material.
In order to achieve the above purpose of the present invention, the following technical solutions are adopted:
in a first aspect, a method for preparing a zinc oxide-barium sulfate composite nano material is provided, which comprises the following steps:
(a) preparing nano zinc oxide by adopting a sol-gel method, and carrying out surface modification on the nano zinc oxide to obtain zinc oxide powder;
(b) dissolving zinc oxide powder in water to obtain a zinc oxide solution, adding a sulfate solution into the zinc oxide solution, uniformly mixing, adding a barium salt solution, and forming a precipitate to obtain the zinc oxide-barium sulfate composite nano material.
Preferably, on the basis of the technical scheme of the invention, the molar ratio of sulfate radicals in the sulfate salt solution and barium ions in the barium salt solution added in the step (b) to zinc oxide in the zinc oxide solution is SO4 2-：Ba2+：ZnO＝1：1：(0.4～0.8)；
Preferably, the molar ratio of the sulfate in the sulfate solution, the barium ions in the barium salt solution and the zinc oxide in the zinc oxide solution added in step (b) is SO4 2-：Ba2+：ZnO＝1：1：(0.4～0.6)。
Preferably, on the basis of the technical scheme of the invention, the sulfate in the step (b) is selected from one or more of sodium sulfate, potassium sulfate, magnesium sulfate or aluminum sulfate; preferably sodium sulfate;
and/or the barium salt is selected from one or more of barium chloride or barium nitrate; barium chloride is preferred;
preferably, after the precipitate is formed in the step (b), separating, washing, re-separating and drying the precipitate to obtain the zinc oxide-barium sulfate composite nanomaterial;
preferably, washing with water for 3-4 times;
preferably, the drying temperature is 50-80 ℃, and the drying time is 8-12 h.
Preferably, on the basis of the technical scheme of the invention, silane coupling agent is adopted to carry out surface modification on the nano zinc oxide in the step (a) to obtain zinc oxide powder;
preferably, the silane coupling agent is one or more selected from APTES, KH550, KH560, KH-570 or LM-N308, and APTES is preferred.
Further, on the basis of the technical scheme of the invention, the step (a) comprises the following steps:
(a1) adding the solution B into the solution A, fully mixing to obtain a mixed solution, and heating the mixed solution to 50-70 ℃ to form nano zinc oxide;
wherein the solution A is a zinc salt-ethanol solution; the solution B is alkali metal hydroxide-ethanol dispersion or weak base;
(a2) adding a silane coupling agent into the mixed solution obtained in the step (a1) to obtain zinc oxide precipitate, separating, drying and washing the precipitate, and then placing the precipitate into an environment with the temperature of 50-70 ℃ for keeping the temperature for 4-6 hours to obtain zinc oxide powder;
preferably, the temperature of the alkali metal hydroxide-ethanol dispersion is 2 to 5 ℃.
Preferably, on the basis of the technical scheme of the invention, the molar ratio of the zinc salt, the alkali metal hydroxide/weak base and the silane coupling agent is 1: (1.4-2): (0.01 to 0.05), preferably 1: (1.4-1.8): (0.01 to 0.03), and more preferably 1: (1.4-1.5): (0.01-0.02).
Preferably, on the basis of the technical scheme of the invention, the zinc salt in the step (a1) is selected from one or more of zinc acetate, zinc chloride, zinc sulfate and zinc nitrate, and preferably zinc acetate;
and/or, the alkali metal hydroxide is selected from one or more of sodium hydroxide, potassium hydroxide or lithium hydroxide;
preferably, the weak base is ammonia.
In a second aspect, the zinc oxide-barium sulfate composite nanomaterial prepared by the preparation method of the zinc oxide-barium sulfate composite nanomaterial is pomegranate-shaped multi-core-shell ZnO-BaSO4A composite nanomaterial.
In a third aspect, an application of the zinc oxide-barium sulfate composite nanomaterial in preparation of a light-emitting device is provided.
In a fourth aspect, there is provided an LED chip coated with the above zinc oxide-barium sulfate composite nanomaterial.
Compared with the prior art, the invention has the following beneficial effects:
(1) the preparation method of the zinc oxide-barium sulfate composite nano material firstly obtains the nano ZnO with modified surface by a sol-gel method, and then adds SO in the nano ZnO through a non-equilibrium adsorption process4 2-Previously, ZnO with a positive charge remained in solution in electrostatic equilibrium when SO was added4 2-When the electrostatic balance is broken, ZnO is gathered into multi-ZnO nuclear luminescent centers, and Ba is added2+When ionic, BaSO4The shell grows around the surface of the luminescent center to form pomegranate-shaped multi-ZnO @ single BaSO4A nanocomposite material of a multi-core-shell structure. In this structure, ZnO serves as an "internal seed" and the surface modifier serves as a "separator", and crystal grains can be separated, thereby effectively realizing ZnO having a strong luminescence. BaSO4As the 'peel' protects ZnO from the influence of external environment, ZnO in the luminescence center has excellent light stability and thermal stability, and the mixed fluorescent powder with high light stability, pH stability and high thermal stability is realized.
(2) The zinc oxide-barium sulfate composite nano material obtained by the method is a pomegranate-shaped multi-core-shell ZnO-BaSO4The composite nanometer material has less fluorescence efficiency reduction of the fluorescent powder after being irradiated by ultraviolet rays for 10 hours, the temperature is increased to 160 ℃, the luminous intensity of the fluorescent powder is basically unchanged, and the fluorescent powder can resist acid and alkali.
(3) The zinc oxide-barium sulfate composite nano material is coated on the UV chip to manufacture the white LED with the adjustable CIE coordinate, the luminous efficiency is high, and the white LED is suitable for daily illumination.
Drawings
FIG. 1 is a schematic diagram of a method for preparing a zinc oxide-barium sulfate composite nanomaterial of the present invention;
FIG. 2 is an electron micrograph of the zinc oxide-barium sulfate composite nanomaterial obtained in example 1 (a) is a TEM image of the zinc oxide-barium sulfate composite nanomaterial obtained in example 1, and (b) is a HRTEM image of the zinc oxide-barium sulfate composite nanomaterial obtained in example 1);
FIG. 3 shows the change of the luminous intensity of the zinc oxide-barium sulfate composite nanomaterial obtained in example 1 and the nano zinc oxide obtained in comparative example 1 under the continuous irradiation of ultraviolet radiation;
FIG. 4 shows the change of luminescence intensity of the zinc oxide-barium sulfate composite nanomaterial obtained in example 1 and the nano zinc oxide obtained in comparative example 1 after annealing in air for 30 min.
Detailed Description
Embodiments of the present invention will be described in detail below with reference to examples, but it will be understood by those skilled in the art that the following examples are only illustrative of the present invention and should not be construed as limiting the scope of the present invention. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.
According to a first aspect of the present invention, there is provided a method for preparing a zinc oxide-barium sulfate composite nanomaterial, comprising the steps of:
(a) preparing nano zinc oxide by adopting a sol-gel method, and carrying out surface modification on the nano zinc oxide to obtain zinc oxide powder;
(b) dissolving zinc oxide powder in water to obtain a zinc oxide solution, adding a sulfate solution into the zinc oxide solution, uniformly mixing, adding a barium salt solution, and forming a precipitate to obtain the zinc oxide-barium sulfate composite nano material.
The sol-gel method for preparing nanoparticles refers to a method for obtaining nanoparticles of oxides or other compounds from metal organic or inorganic compounds by solidifying the particles through the processes of solution, sol, gel, etc., and then performing heat treatment.
The invention utilizes the sol-gel method to prepare the nano zinc oxide, the specific preparation method is not limited, the conventional method in the field can be adopted, the precursor can adopt metal alkoxide compounds, and the zinc salt can also be adopted as the raw material to prepare the nano zinc oxide powder.
The surface energy of the nano zinc oxide particles is high, and the nano zinc oxide particles are in a thermodynamic unstable state and are easy to aggregate, so that the actual application effect of the nano particles is influenced; the zinc oxide shows that the nano zinc oxide is hydrophilic and oleophobic, is strong in polarity, is difficult to uniformly disperse in an organic medium, has no binding force with a base material, easily causes interface defects, and causes the performance reduction of the material, so that the nano zinc oxide is subjected to surface modification to eliminate the surface high energy potential, adjust the hydrophobicity, and improve the wettability and the binding force with the organic base material, thereby improving the performance and the filling amount of the material to the maximum extent, and reducing the cost of the raw material.
The surface modification of the nano zinc oxide is usually carried out by adopting a coupling agent treatment method, wherein the coupling agent has an amphoteric structure, one end of the coupling agent is hydrophilic to the nano particles, the other end of the coupling agent is hydrophilic to organic matters, one end of the hydrophilic to nano particles is combined with the nano particles so as to reduce the surface energy of the nano particles, and the other end of the hydrophilic to organic matters can improve the compatibility with a polymer matrix. Commonly used coupling agents include titanate coupling agents or silane coupling agents.
In the step (b), the zinc oxide-barium sulfate composite nanomaterial is prepared through a non-equilibrium adsorption process, as shown in fig. 1, the zinc oxide is positively charged on the surface in a water environment, and SO is added4 2-Previously, ZnO with a positive charge was kept in electrostatic equilibrium when SO was added4 2-When the electrostatic equilibrium is broken, and ZnO collects as multi-ZnO nuclear luminescent centers. Then adding Ba2+When ionic, BaSO4The shell grows around the surface of the luminescent center to form pomegranate-shaped multi-ZnO @ single BaSO4A nanocomposite material of a multi-core-shell structure. In this structure, ZnO corresponds to a seed (pomegranate seed) and forms a luminescence center, BaSO4The shell is equivalent to seed coat (pomegranate rind), ZnO in the luminescent center can separate crystal grains through surface modification by a surface modifier, the surface modifier is equivalent to a diaphragm, the insulating effect is achieved, quenching caused by aggregation is avoided, and BaSO4The shell is a protective layer and provides a protective effect for the internal luminescence center, so that the luminescence center ZnO has excellent light stability and thermal stability, and high light stability and high pH stability are realizedAnd mixed fluorescent powder with high thermal stability.
In a preferred embodiment, the molar ratio of sulfate in the sulfate solution, barium ions in the barium salt solution and zinc oxide in the zinc oxide solution added in step (b) is SO4 2-：Ba2+：ZnO＝1：1：(0.4～0.8)。
The amount of sulfate, barium ion and zinc oxide is typically, but not limited to, in a molar ratio such as SO4 2-：Ba2+: 1-ZnO: 1: 0.4, 1: 1: 0.5, 1: 1: 0.6, 1: 1: 0.7 or 1: 1: 0.8.
the molar ratio of sulfate radical to barium ion is 1: 1, ensuring that sulfate radical and barium ions can completely form barium sulfate.
The ZnO content is too low, redundant barium sulfate exists, the barium sulfate does not emit light, the overall performance of the composite material is reduced, and the ZnO content is too high, so that a part of zinc oxide can not be coated with the barium sulfate, and the performance of the zinc oxide fluorescent powder coated with the barium sulfate is not as good as that of the zinc oxide fluorescent powder coated with the barium sulfate completely.
In a preferred embodiment, the molar ratio of sulfate in the sulfate solution, barium ions in the barium salt solution and zinc oxide in the zinc oxide solution added in step (b) is SO4 2-：Ba2+：ZnO＝1：1：(0.4～0.6)。
By further optimizing the proportion of sulfate radicals, barium ions and zinc oxide, the zinc oxide-barium sulfate composite material with better performance can be obtained.
In a preferred embodiment, the sulfate in step (b) is selected from one or more of sodium sulfate, potassium sulfate, magnesium sulfate or aluminum sulfate; sodium sulfate is preferred.
The sulfate provides sulfate.
In a preferred embodiment, the barium salt is selected from one or more of barium chloride or barium nitrate; barium chloride is preferred.
The barium salt provides barium ions.
In a preferred embodiment, after the precipitate is formed in step (b), the precipitate is separated, washed, re-separated and dried to obtain the zinc oxide-barium sulfate composite nanomaterial.
Separating, preferably centrifuging the precipitate; washing is preferably carried out for 3-4 times by using water; the washed precipitate is then preferably centrifuged.
Preferably, the drying temperature is 50-80 ℃, and the drying time is 8-12 h.
Drying temperatures are typically, but not limited to, for example, 50 ℃, 60 ℃, 70 ℃ or 80 ℃; typical but non-limiting drying times are for example 8h, 9h, 10h, 11h or 12 h.
In a preferred embodiment, in the step (a), the nano zinc oxide is subjected to surface modification by using a silane coupling agent to obtain zinc oxide powder;
preferably, the silane coupling agent is one or more selected from APTES, KH550, KH560, KH-570 or LM-N308, and APTES is preferred.
APTES is 3-aminopropyl triethoxysilane, APTES is adopted to carry out surface modification on zinc oxide, zinc oxide with amino on the surface is obtained, and meanwhile, the zinc oxide at the luminescence center is insulated by a silicon dioxide layer to avoid quenching caused by aggregation.
In a preferred embodiment, step (a) comprises the steps of:
(a1) adding the solution B into the solution A, fully mixing to obtain a mixed solution, and heating the mixed solution to 50-70 ℃ to form nano zinc oxide;
wherein the solution A is a zinc salt-ethanol solution; the solution B is alkali metal hydroxide-ethanol dispersion or weak base;
(a2) adding a silane coupling agent into the mixed solution obtained in the step (a1) to obtain zinc oxide precipitate, separating, drying and washing the precipitate, and then placing the precipitate into an environment with the temperature of 50-70 ℃ for keeping the temperature for 4-6 hours to obtain zinc oxide powder.
The zinc salt is used as a raw material in the step (a), the nano zinc oxide powder is prepared in an alkaline environment, the preparation method is simple, the particle size of the obtained nano zinc oxide powder is uniform, and the problem of high cost of preparing the nano zinc oxide by using a metal alkoxide compound as a precursor is solved.
The temperature of the mixture in step (a1) is typically, but not limited to, 50 ℃, 60 ℃ or 70 ℃.
The separation in step (a2) is preferably performed by centrifugation of the pellet; washing is preferably carried out for 3-4 times by using water; the temperature of the drying environment after washing is typically, but not limited to, 50 ℃, 60 ℃ or 70 ℃, for example; drying times are typically, but not limited to, 4h, 5h or 6h, for example.
Preferably, the temperature of the alkali metal hydroxide-ethanol dispersion is 2 to 5 ℃, for example 2 ℃, 3 ℃, 4 ℃ or 54 ℃.
In a preferred embodiment, the zinc salt, alkali metal hydroxide/weak base and silane coupling agent are used in a molar ratio of 1: (1.4-2): (0.01 to 0.05), preferably 1: (1.4-1.8): (0.01 to 0.03), and more preferably 1: (1.4-1.5): (0.01-0.02).
"alkali metal hydroxide/weak base" refers to an alkali metal hydroxide or a weak base. The "molar ratio of zinc salt, alkali metal hydroxide/weak base and silane coupling agent used" means the molar ratio of zinc salt, alkali metal hydroxide and silane coupling agent used or the molar ratio of zinc salt, weak base and silane coupling agent used.
The molar ratio of the amounts of zinc salt, alkali metal hydroxide/weak base and silane coupling agent used is typically, but not limited to, for example, 1: 1.4: 0.01, 1: 1.4: 0.013, 1: 1.4: 0.015, 1: 1.4: 0.02, 1: 1.4: 0.03, 1: 1.4: 0.04, 1: 1.4: 0.05, 1: 1.5: 0.01, 1: 1.5: 0.013, 1: 1.5: 0.015, 1: 1.6: 0.01, 1: 1.6: 0.013, 1: 1.6: 0.015, 1: 1.8: 0.01, 1: 1.8: 0.013, 1: 1.8: 0.015, 1: 2: 0.01, 1: 2: 0.013 or 1: 2: 0.015.
by optimizing the proportion of zinc salt, alkali metal hydroxide/weak base and silane coupling agent, better modification effect can be obtained, and nano zinc oxide powder with positively charged surface can be obtained.
In the step (a1), the zinc salt is preferably selected from one or more of zinc acetate, zinc chloride, zinc sulfate or zinc nitrate, and is preferably zinc acetate.
The alkali metal hydroxide is preferably selected from one or more of sodium hydroxide, potassium hydroxide or lithium hydroxide; the weak base is preferably ammonia.
A preparation method of a typical zinc oxide-barium sulfate composite nano material comprises the following steps:
(a) adding the solution B into the solution A, fully mixing to obtain a mixed solution, and heating the mixed solution to 50-70 ℃ to form nano zinc oxide;
wherein the solution A is a zinc salt-ethanol solution; the solution B is alkali metal hydroxide-ethanol dispersion;
(b) adding a silane coupling agent into the mixed solution obtained in the step (a) to obtain zinc oxide precipitate, centrifugally drying the precipitate, cleaning for three or four times to remove unreacted raw materials, and keeping the remained precipitate in an environment at 50-70 ℃ for 4-6 hours to obtain zinc oxide powder;
wherein the molar ratio of the zinc salt to the alkali metal hydroxide to the silane coupling agent is 1: (1.4-1.5): (0.01-0.02);
(c) dissolving a certain amount of zinc oxide powder in water to obtain a zinc oxide solution, and performing a molar ratio SO4 2-：Ba2+: 1-ZnO: 1: (0.4-0.6) adding a sulfate solution into the zinc oxide solution, uniformly mixing, adding a barium salt solution to form a precipitate, centrifuging the precipitate, washing with water for three times, centrifuging the precipitate, and drying at 50-80 ℃ for 8-12 hours to obtain the zinc oxide-barium sulfate composite nano material.
According to a second aspect of the present invention, there is provided a zinc oxide-barium sulfate composite nanomaterial prepared by the above preparation method of the zinc oxide-barium sulfate composite nanomaterial, wherein the zinc oxide-barium sulfate composite nanomaterial is pomegranate-shaped multi-core-shell ZnO-BaSO4A composite nanomaterial.
The zinc oxide-barium sulfate composite nano material obtained by the method is ZnO-BaSO with a pomegranate-shaped multi-core-shell structure4Composite nanomaterial, punica granatum-like "ZnO-seed-BaSO4The seed coat' nano structure can improve the stability of ZnO. In this structure, ZnO serves as an "internal seed" and a surface modifier (coupling agent) serves as a separator, so that crystal grains can be separated, and ZnO having a strong light-emitting property can be effectively realized. BaSO4As a 'peel', ZnO is protected from the influence of external environment, and the mixed fluorescent powder with high light, pH and thermal stability is realized.
According to a third aspect of the present invention, there is provided a use of the above zinc oxide-barium sulfate composite nanomaterial in the preparation of a light emitting device.
A typical but non-limiting light emitting device is for example an LED.
The zinc oxide-barium sulfate composite nano material is used as fluorescent powder in a light-emitting device, for example, the fluorescent powder is coated on a UV chip to manufacture a white LED with an adjustable CIE coordinate, the luminous efficiency is high, the fluorescent powder is suitable for daily illumination, and the service life of the fluorescent powder is prolonged.
According to a fourth aspect of the present invention, there is provided an LED chip coated with the above zinc oxide-barium sulfate composite nanomaterial.
Typical but non-limiting LED chips are UV pumped LEDs.
The LED chip can still keep higher luminous efficiency after long-time work by coating the zinc oxide-barium sulfate composite nano material.
The invention is further illustrated by the following specific examples and comparative examples, but it should be understood that these examples are for purposes of illustration only and are not to be construed as limiting the invention in any way. All the raw materials related to the invention can be obtained commercially.
Example 1
A preparation method of a zinc oxide-barium sulfate composite nano material comprises the following steps:
(1) 11g of zinc acetate was weighed, dissolved in alcohol and stirred continuously.
(2) 2g of potassium hydroxide is weighed, dissolved in alcohol, dispersed by ultrasonic, and then cooled to 4 ℃.
(3) Add (2) to (1) and continue stirring, whereupon the solution in (1) is cloudy and then clear, and the temperature is raised to 60 ℃ whereupon zinc oxide forms.
(4) 800. mu.L of APTES was added to 3mL of water and added to the solution in (3), whereupon the solution became cloudy and zinc oxide precipitated.
(5) The precipitate was centrifuged and dried, and washed three or four times to remove unreacted materials.
(6) The remaining precipitate was put into a drying oven and heated to 60 ℃ for 5 hours to obtain zinc oxide powder.
(7) 0.324g of the above zinc oxide powder was weighed out and dissolved in 30mL of water to form a clear and transparent solution.
(8) Sodium sulfate 1.42g was weighed and added to the above solution with continuous stirring for five minutes.
(9) 2.44g of barium chloride was weighed out and dissolved in 10mL of water, and the above solution was added to (8) and stirring was continued for 5 minutes, at which time a precipitate formed.
(10) The precipitate was centrifuged, washed three times with water, centrifuged and dried at 60 ℃ for 10 hours.
(11) Obtaining the fluorescent powder.
Example 2
A preparation method of a zinc oxide-barium sulfate composite nano material comprises the following steps:
(1) 14.875g of zinc nitrate was weighed, dissolved in alcohol, and stirred continuously.
(2) 1.43g of sodium hydroxide was weighed, dissolved in alcohol, dispersed by ultrasonic, and then cooled to 2 ℃.
(3) Add (2) to (1) and continue stirring, whereupon the solution in (1) is cloudy and then clear, and the temperature is raised to 60 ℃ whereupon zinc oxide forms.
(4) 800. mu.L of APTES was added to 3mL of water and added to the solution in (3), whereupon the solution became cloudy and zinc oxide precipitated.
(5) The precipitate was centrifuged and dried, and washed three or four times to remove unreacted materials.
(6) The remaining precipitate was put into a drying oven and heated to 50 ℃ for 6 hours to obtain zinc oxide powder.
(7) 0.648g of the above zinc oxide powder was weighed out and dissolved in 30mL of water to form a clear and transparent solution.
(8) Potassium sulfate, 1.74g, was weighed and added to the above solution with continuous stirring for five minutes.
(9) 2.44g of barium chloride was weighed out and dissolved in 10mL of water, and the above solution was added to (8) and stirring was continued for 5 minutes, at which time a precipitate formed.
(10) The precipitate was centrifuged, washed three times with water, centrifuged and dried at 50 ℃ for 12 hours.
(11) Obtaining the fluorescent powder.
Example 3
A preparation method of a zinc oxide-barium sulfate composite nano material comprises the following steps:
(1) 11g of zinc acetate was weighed, dissolved in alcohol and stirred continuously.
(2) 2g of potassium hydroxide is weighed, dissolved in alcohol, dispersed by ultrasonic, and then cooled to 5 ℃.
(3) Add (2) to (1) and continue stirring, whereupon the solution in (1) is cloudy and then clear, and the temperature is raised to 60 ℃ whereupon zinc oxide forms.
(4) 700 μ L of APTES was added to 2mL of water and added to the solution in (3) where the solution was cloudy and zinc oxide precipitated.
(5) The precipitate was centrifuged and dried, and washed three or four times to remove unreacted materials.
(6) The remaining precipitate was put into a drying oven and heated to 70 ℃ for 4 hours to obtain zinc oxide powder.
(7) 0.4g of the above zinc oxide powder was weighed out and dissolved in 30mL of water to form a clear and transparent solution.
(8) Magnesium sulfate, 1.20g, was weighed and added to the above solution with continuous stirring for five minutes.
(9) 2.44g of barium chloride was weighed out and dissolved in 10mL of water, and the above solution was added to (8) and stirring was continued for 5 minutes, at which time a precipitate formed.
(10) The precipitate was centrifuged, washed three times with water, centrifuged and dried at 80 ℃ for 8 hours.
(11) Obtaining the fluorescent powder.
Example 4
A preparation method of a zinc oxide-barium sulfate composite nano material comprises the following steps:
(1) 6.8g of zinc chloride was weighed, dissolved in alcohol and stirred continuously.
(2) 1.6758g of lithium hydroxide was weighed, dissolved in alcohol, dispersed by sonication, and the temperature was lowered to 4 ℃ after dispersion.
(3) Add (2) to (1) and continue stirring, whereupon the solution in (1) is cloudy and then clear, and the temperature is raised to 60 ℃ whereupon zinc oxide forms.
(4) 800. mu.L of APTES was added to 3mL of water and added to the solution in (3), whereupon the solution became cloudy and zinc oxide precipitated.
(5) The precipitate was centrifuged and dried, and washed three or four times to remove unreacted materials.
(6) The remaining precipitate was put into a drying oven and heated to 60 ℃ for 5 hours to obtain zinc oxide powder.
(7) 0.5g of the above zinc oxide powder was weighed out and dissolved in 30mL of water to form a clear and transparent solution.
(8) Potassium sulfate, 1.74g, was weighed and added to the above solution with continuous stirring for five minutes.
(9) 2.44g of barium chloride was weighed out and dissolved in 10mL of water, and the above solution was added to (8) and stirring was continued for 5 minutes, at which time a precipitate formed.
(10) The precipitate was centrifuged, washed three times with water, centrifuged and dried at 70 ℃ for 10 hours.
(11) Obtaining the fluorescent powder.
Example 5
A preparation method of a zinc oxide-barium sulfate composite nano material comprises the following steps:
(1) weighing 8.05g of zinc sulfate, dissolving in alcohol and continuously stirring.
(2) 2g of potassium hydroxide is weighed, dissolved in alcohol, dispersed by ultrasonic, and then cooled to 4 ℃.
(3) Add (2) to (1) and continue stirring, whereupon the solution in (1) is cloudy and then clear, and the temperature is raised to 60 ℃ whereupon zinc oxide forms.
(4) 750 μ L of APTES was added to 2.5mL of water and added to the solution in (3) where the solution was cloudy and zinc oxide precipitated.
(5) The precipitate was centrifuged and dried, and washed three or four times to remove unreacted materials.
(6) The remaining precipitate was put into a drying oven and heated to 60 ℃ for 5 hours to obtain zinc oxide powder.
(7) 0.35g of the above zinc oxide powder was weighed out and dissolved in 30mL of water to form a clear and transparent solution.
(8) Magnesium sulfate, 1.20g, was weighed and added to the above solution with continuous stirring for five minutes.
(9) 2.44g of barium chloride was weighed out and dissolved in 10mL of water, and the above solution was added to (8) and stirring was continued for 5 minutes, at which time a precipitate formed.
(10) The precipitate was centrifuged, washed three times with water, centrifuged and dried at 60 ℃ for 10 hours.
(11) Obtaining the fluorescent powder.
Example 6
A preparation method of a zinc oxide-barium sulfate composite nano material comprises the following steps:
(1) 11g of zinc acetate was weighed, dissolved in alcohol and stirred continuously.
(2) 1.6758g of lithium hydroxide was weighed, dissolved in alcohol, dispersed by sonication, and the temperature was lowered to 4 ℃ after dispersion.
(3) Add (2) to (1) and continue stirring, whereupon the solution in (1) is cloudy and then clear, and the temperature is raised to 60 ℃ whereupon zinc oxide forms.
(4) 750 μ L of APTES was added to 2.5mL of water and added to the solution in (3) where the solution was cloudy and zinc oxide precipitated.
(5) The precipitate was centrifuged and dried, and washed three or four times to remove unreacted materials.
(6) The remaining precipitate was put into a drying oven and heated to 60 ℃ for 5 hours to obtain zinc oxide powder.
(7) 0.45g of the above zinc oxide powder was weighed out and dissolved in 30mL of water to form a clear and transparent solution.
(8) Sodium sulfate 1.42g was weighed and added to the above solution with continuous stirring for five minutes.
(9) 2.44g of barium chloride was weighed out and dissolved in 10mL of water, and the above solution was added to (8) and stirring was continued for 5 minutes, at which time a precipitate formed.
(10) The precipitate was centrifuged, washed three times with water, centrifuged and dried at 80 ℃ for 10 hours.
(11) Obtaining the fluorescent powder.
Example 7
A method for preparing a zinc oxide-barium sulfate composite nanomaterial, wherein the mass of the zinc oxide powder in step (7) is 0.1g, and the remaining steps are the same as in example 1.
Example 8
A method for preparing a zinc oxide-barium sulfate composite nanomaterial, wherein the mass of the zinc oxide powder in step (7) is 1g, and the remaining steps are the same as in example 1.
Example 9
A preparation method of zinc oxide-barium sulfate composite nano material is provided, wherein 100 μ L APTES is taken in step (4) and added into 3mL water, and the rest steps are the same as the example 1.
Comparative example 1
A preparation method of nano zinc oxide comprises the following steps:
(1) 11g of zinc acetate was weighed, dissolved in alcohol and stirred continuously.
(2) 2g of potassium hydroxide is weighed, dissolved in alcohol, dispersed by ultrasonic, and then cooled to 4 ℃.
(3) Add (2) to (1) and continue stirring, whereupon the solution in (1) is cloudy and then clear, and the temperature is raised to 60 ℃ whereupon zinc oxide forms.
(4) 800. mu.L of APTES was added to 3mL of water and added to the solution in (3), whereupon the solution became cloudy and zinc oxide precipitated.
(5) The precipitate was centrifuged and dried, and washed three or four times to remove unreacted materials.
(6) The remaining precipitate was put into a drying oven and heated to 60 ℃ for 5 hours to obtain zinc oxide powder.
Comparative example 2
A preparation method of nano zinc oxide comprises the following steps:
(1) 14.875g of zinc nitrate was weighed, dissolved in alcohol, and stirred continuously.
(2) 1.43g of sodium hydroxide was weighed, dissolved in alcohol, dispersed by ultrasonic, and then cooled to 2 ℃.
(3) Add (2) to (1) and continue stirring, whereupon the solution in (1) is cloudy and then clear, and the temperature is raised to 60 ℃ whereupon zinc oxide forms.
(4) 800. mu.L of APTES was added to 3mL of water and added to the solution in (3), whereupon the solution became cloudy and zinc oxide precipitated.
(5) The precipitate was centrifuged and dried, and washed three or four times to remove unreacted materials.
(6) The remaining precipitate was put into a drying oven and heated to 50 ℃ for 6 hours to obtain zinc oxide powder.
Comparative example 3
A preparation method of nano zinc oxide comprises the following steps:
(1) 11g of zinc acetate was weighed, dissolved in alcohol and stirred continuously.
(2) 2g of potassium hydroxide is weighed, dissolved in alcohol, dispersed by ultrasonic, and then cooled to 5 ℃.
(3) Add (2) to (1) and continue stirring, whereupon the solution in (1) is cloudy and then clear, and the temperature is raised to 60 ℃ whereupon zinc oxide forms.
(4) 700 μ L of APTES was added to 2mL of water and added to the solution in (3) where the solution was cloudy and zinc oxide precipitated.
(5) The precipitate was centrifuged and dried, and washed three or four times to remove unreacted materials.
(6) The remaining precipitate was put into a drying oven and heated to 70 ℃ for 4 hours to obtain zinc oxide powder.
Fig. 2 is an electron micrograph of the zinc oxide-barium sulfate composite nanomaterial obtained in example 1, fig. 2 (a) is a TEM image of the zinc oxide-barium sulfate composite nanomaterial obtained in example 1, and fig. 2 (b) is a HRTEM image of the zinc oxide-barium sulfate composite nanomaterial obtained in example 1.
As shown in figure 2, the particle size of the composite is 50-200 nm, a core-shell structure is obviously observed in the figure, the shaded part is a zinc oxide luminescence center, and barium sulfate forms a protective layer outside the zinc oxide core. It is observed from the high-resolution transmission electron micrograph that the lattice spacing of 0.21nm corresponds to the lattice of barium sulfate, and the lattice spacing of 0.26nm corresponds to the lattice of zinc oxide, and the zinc oxide core is wrapped by barium sulfate.
The zinc oxide-barium sulfate composite nano-materials obtained in examples 1 to 9 and the nano-zinc oxide obtained in comparative examples 1 to 3 were subjected to light stability, thermal stability and pH stability tests, the specific test methods were as follows:
(1) and (3) testing the light stability: samples of the same mass were taken, irradiated under the UV lamp for 5 hours, and sampled every 1 hour to measure the fluorescence intensity.
(2) And (3) testing thermal stability: and (3) taking samples with the same mass, annealing the samples in the air of a tubular furnace for 30 minutes at the temperature range of 60-220 ℃ at the temperature interval of 10 ℃, and testing the fluorescence spectrum of the samples after annealing.
(3) And (3) testing the pH stability: and (3) taking samples with the same mass, respectively soaking the samples in aqueous solution with the pH value of 1-12 for half an hour, and drying the fluorescence spectrum of the test sample after half an hour.
The test results are shown in table 1.
TABLE 1
From the results in table 1, it can be seen that the zinc oxide-barium sulfate composite nanomaterial obtained by the method of the present invention has a fluorescence intensity change of less than 15% before and after being continuously irradiated for 5h by ultraviolet radiation, a fluorescence intensity change before and after annealing at a high temperature for 30min, a fluorescence intensity change before and after soaking in an aqueous solution with a pH of 1 for 30min of not more than 10%, and has high light stability, thermal stability and pH stability. The nano zinc oxide obtained in the comparative examples 1 to 3 has poor stability and serious light decay in light and heat environments and is not resistant to acid, alkali and various organic solvents.
FIG. 3 is a graph showing the change in luminous intensity of the zinc oxide-barium sulfate composite nanomaterial obtained in example 1 and the nano zinc oxide obtained in comparative example 1 under continuous irradiation of ultraviolet radiation (the luminous intensity values are normalized values). As can be seen from FIG. 3, the fluorescence intensity of the zinc oxide-barium sulfate composite nanomaterial of the invention slowly decreases with the time, the fluorescence efficiency of the phosphor decreases less after 10 hours of ultraviolet irradiation, and the fluorescence of the zinc oxide quantum dots attenuates significantly and rapidly, especially decays more rapidly after 4 hours of continuous ultraviolet irradiation.
FIG. 4 shows the change of luminescence intensity (the value of luminescence intensity is normalized) of the zinc oxide-barium sulfate composite nanomaterial obtained in example 1 and the nano zinc oxide obtained in comparative example 1 after annealing in air for 30 min. As can be seen from FIG. 4, in the environment of over 100 ℃, the zinc oxide-barium sulfate composite nanomaterial of the present invention can still maintain high fluorescence intensity, the temperature rises to 160 ℃, the luminous intensity of the phosphor is basically unchanged, and the fluorescence intensity of the zinc oxide quantum dots is obviously attenuated after the temperature exceeds 140 ℃.
Further analysis revealed that example 7 had too little zinc oxide in step (7) compared to example 1, and example 8 had too much zinc oxide in step (7) compared to example 1, and as a result, it was found that the light stability of the zinc oxide-barium sulfate composite nanomaterial obtained in example 1 was better than that of the zinc oxide-barium sulfate composite nanomaterial obtained in examples 7 and 8, because too little ZnO had excess barium sulfate, and barium sulfate itself did not emit light, reducing the overall performance of the composite material, and too much ZnO had some zinc oxide not coated with barium sulfate, which was not as good as the stability of the zinc oxide phosphor completely coated with barium sulfate.
Further analysis shows that the amount of APTES used in step (4) is different in example 1 compared with example 9, and as a result, the photostability of the zinc oxide-barium sulfate composite nanomaterial obtained in example 1 is better than that of the zinc oxide-barium sulfate composite nanomaterial obtained in example 9, and thus it can be seen that the amount of the coupling agent used has an influence on the surface modification of zinc oxide, and a better effect can be obtained within a preferred amount range.
While particular embodiments of the present invention have been illustrated and described, it would be obvious that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.
Claims (18)
1. A preparation method of a zinc oxide-barium sulfate composite nano material is characterized by comprising the following steps:
(a) preparing nano zinc oxide by adopting a sol-gel method, and carrying out surface modification on the nano zinc oxide to obtain zinc oxide powder;
the step (a) includes the steps of:
(a1) adding the solution B into the solution A, fully mixing to obtain a mixed solution, and heating the mixed solution to 50-70 ℃ to form nano zinc oxide;
wherein the solution A is a zinc salt-ethanol solution; the solution B is alkali metal hydroxide-ethanol dispersion or weak base;
(a2) adding a silane coupling agent into the mixed solution obtained in the step (a1) to obtain zinc oxide precipitate, separating, drying and washing the precipitate, and then placing the precipitate into an environment with the temperature of 50-70 ℃ for keeping the temperature for 4-6 hours to obtain zinc oxide powder;
(b) dissolving zinc oxide powder in water to obtain a zinc oxide solution, adding a sulfate solution into the zinc oxide solution, uniformly mixing, adding a barium salt solution, and forming a precipitate to obtain the zinc oxide-barium sulfate composite nano material.
2. The method for preparing zinc oxide-barium sulfate composite nanomaterial according to claim 1, wherein the molar ratio of sulfate in the sulfate solution, barium ions in the barium salt solution, and zinc oxide in the zinc oxide solution added in step (b) is SO4 2-：Ba2+：ZnO＝1：1：(0.4～0.8)。
3. The zinc oxide-barium sulfate composite nanomaterial of claim 2The preparation method of the material is characterized in that the molar ratio of sulfate radical in the sulfate salt solution added in the step (b), barium ions in the barium salt solution and zinc oxide in the zinc oxide solution is SO4 2-：Ba2+：ZnO＝1：1：(0.4～0.6)。
4. The method for preparing zinc oxide-barium sulfate composite nanomaterial according to claim 1, wherein the sulfate in step (b) is selected from one or more of sodium sulfate, potassium sulfate, magnesium sulfate or aluminum sulfate;
and/or the barium salt is selected from one or more of barium chloride or barium nitrate.
5. The method of preparing a zinc oxide-barium sulfate composite nanomaterial according to claim 1, wherein the precipitate formed in the step (b) is separated, washed, re-separated and dried to obtain the zinc oxide-barium sulfate composite nanomaterial.
6. The method for preparing zinc oxide-barium sulfate composite nanomaterial according to claim 5, wherein the zinc oxide-barium sulfate composite nanomaterial is washed with water 3 to 4 times.
7. The method for preparing zinc oxide-barium sulfate composite nanomaterial according to claim 5, wherein the drying temperature is 50-80 ℃ and the drying time is 8-12 hours.
8. The method for preparing zinc oxide-barium sulfate composite nanomaterial according to any of claims 1 to 4, wherein the silane coupling agent is one or more selected from APTES, KH550, KH560, KH-570 or LM-N308.
9. The method for preparing zinc oxide-barium sulfate composite nanomaterial according to claim 8, wherein the silane coupling agent is selected from APTES.
10. The method for preparing a zinc oxide-barium sulfate composite nanomaterial according to any one of claims 1 to 4, wherein the temperature of the alkali metal hydroxide-ethanol dispersion is 2 to 5 ℃.
11. The method for preparing zinc oxide-barium sulfate composite nanomaterial according to claim 1, wherein the molar ratio of the amounts of zinc salt, alkali metal hydroxide/weak base and silane coupling agent is 1: (1.4-2): (0.01-0.05).
12. The method for preparing zinc oxide-barium sulfate composite nanomaterial according to claim 11, wherein the molar ratio of the amounts of zinc salt, alkali metal hydroxide/weak base and silane coupling agent is 1: (1.4-1.8): (0.01-0.03).
13. The method for preparing zinc oxide-barium sulfate composite nanomaterial according to claim 11, wherein the molar ratio of the amounts of zinc salt, alkali metal hydroxide/weak base and silane coupling agent is 1: (1.4-1.5): (0.01-0.02).
14. The method for preparing zinc oxide-barium sulfate composite nanomaterial of claim 1, wherein the zinc salt in step (a1) is selected from one or more of zinc acetate, zinc chloride, zinc sulfate or zinc nitrate,
and/or, the alkali metal hydroxide is selected from one or more of sodium hydroxide, potassium hydroxide or lithium hydroxide.
15. The method for preparing zinc oxide-barium sulfate composite nanomaterial according to claim 1, wherein the weak base in step (a1) is ammonia water.
16. The zinc oxide-barium sulfate composite nanomaterial prepared by the method for preparing the zinc oxide-barium sulfate composite nanomaterial according to any one of claims 1 to 15, wherein the zinc oxide-barium sulfate composite nanomaterial is pomegranate-shaped multi-core-shell ZnO-BaSO4A composite nanomaterial.
17. Use of the zinc oxide-barium sulfate composite nanomaterial of claim 16 in the preparation of a light-emitting device.
18. An LED chip coated with the zinc oxide-barium sulfate composite nanomaterial of claim 16.
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