HK1110832B - New process for large-scale production of monodisperse nanoparticles - Google Patents

Description

Novel method for large-scale production of monodisperse nanoparticles

Technical Field

The present invention relates to a novel method for large-scale production of monodisperse nanoparticles. More particularly, the present invention relates to a method for preparing metal, metal alloy, metal oxide and multi-metal oxide nanoparticles, comprising the steps of: metal salts dissolved in aqueous solution and salts dissolved in a solvent selected from the group consisting of C_5-10Aliphatic hydrocarbons and C_6-10Alkali metal C of the first solvent of aromatic hydrocarbons_4-25Carboxylate salt transForming a metal carboxylate complex, and b) heating said metal carboxylate complex dissolved in a second solvent selected from C to obtain nanoparticles_6-25Aromatic compound, C_6-25Ethers, C_6-25Aliphatic hydrocarbons and C_6-25An amine.

Background

Murray et al, in U.S. Pat. No. 6,262,129B 1, disclose a method for synthesizing transition metal nanoparticles by reaction of high temperature metal precursors (metal precursors), in which the cost of size selection methods to control desired properties to obtain uniform size is high and difficult to use for large scale production of monodisperse nanoparticles, and thus, the method is not suitable for large scale production of base materials.

Monodisperse Gold nanoparticles have been synthesized by digestion Ripening of initially polydisperse nanoparticles (Stoeva, S.et al, "Gram-seal Synthesis of Monochromatic Gold colloid by the Solvaded Metal atomic Dispersion Method and diagnostic thickening and therapeutic organic hybridization in Two-and Three-Dimensional Structures", J.Am.chem.Soc.2002, 124, 2305).

However, the long aging time and the difficulty in controlling the uniformity of the size are unfavorable factors for the mass synthesis of the monodisperse gold nanoparticles.

Hyeon, t. et al discloses a Synthesis process without Size Selection process of monodisperse iron oxide nanoparticles obtained from the thermal decomposition of iron oleate obtained from the reaction of iron pentacarbonyl and oleic acid (Hyeon, t.et al, "Synthesis of Highly-Crystalline and monidosis maize nanocrystalites with out a Size-Selection process," j.am.chem.soc.2001, 123, 12798). However, iron pentacarbonyl as precursor is highly toxic and this method is not suitable for large scale production of monodisperse nanoparticles.

PuntesV. et al report the reaction of cobalt dicarbonyl via octacarbonyl (Co)₂(CO)₈) A method of synthesizing monodisperse cobalt nanoparticles by thermal decomposition in the presence of a surfactant (Puntes, v.f. et., "Colloidal nanocrystalline Shape and Size Control: the Caseoof Cobalt ", Science 2001, 291, 2115). However, the use of expensive and highly toxic cobalt octacarbonyl is a disadvantageous factor for the synthesis of large amounts of monodisperse particles.

Sun, S. et al reported the synthesis of metallic iron salts (MFe) by thermal decomposition of metal acetate in the presence of oleic acid and oleylamine₂O₄Method for Monodisperse nanoparticles of M ═ Fe, Co or Mn) (Sun, s.et al, "monodiscerse MFe₂O₄(M ═ Fe, Co, Mn) nanoparticules ", j.am. chem.soc.2004, 126, 273; sun, S.et., "Size-Controlled Synthesis of magnetic Nanoparticles", J.Am.chem.Soc.2002, 124, 8204). The use of expensive metal acetates prevents the synthesis of large amounts of monodisperse particles.

Jana, N.et al disclose a Simple method for synthesizing metal oxide nanoparticles by pyrolysis of metal fatty acid salts ([ Jana, N.et al, "Size-and shape-Controlled Magnetic (Cr, Mn, Fe, Co, Ni) oxide nanoparticles via Simple and General Approach", chem. Mater.2004, 16, 3931).

Although this synthetic process has some advantages over the prior art cited above, such as being relatively safe and using inexpensive metal fatty acid salts. But the weaknesses of this method are: in order to obtain the metal fatty acid salt, a mixture of the metal salt, the fatty acid and NaOH is required to be put into a reactor for reaction, and then neutralization and purification are performed, which is time-consuming and difficult. Therefore, this disadvantage makes it difficult to synthesize monodisperse nanoparticles in large amounts.

Also, Yu, W. et al reported a method for producing Monodisperse magnetite Nanoparticles by thermal Decomposition of metal fatty acid Salts, similar to the method disclosed in Jana et al above (Yu, W.et al, "Synthesis of Monodissperse Iron Oxide Nanoparticles by thermal Decomposition of Iron carbonate Salts", chem. Comm.2004, 2306).

In order to overcome the disadvantages of the prior art, the present inventors have studied a new method for mass-synthesizing monodisperse nanoparticles using inexpensive and non-toxic metal salts as reactants, which has a single reaction suitable for synthesizing up to 100 g of monodisperse nanoparticles, uses 500ml of a solvent for the single reaction, does not require a size selection process, and has a simple size control of monodisperse nanoparticles by changing synthesis conditions.

The present inventors have realized a new method for preparing nanoparticles of transition metals, metal alloys, metal oxides, multi-metal oxides and other metal compounds.

Accordingly, it is a primary object of the present invention to provide a method for mass production of metal, metal alloy, metal oxide and multi-metal oxide monodisperse nanoparticles using non-toxic and inexpensive metal salts without size selection process.

Disclosure of Invention

Technical problem

Since nanoparticles can be used as a material in the emerging field of nanotechnology, research into various nanoparticles (also referred to as nanocrystals) has been actively conducted. These nanoparticles can be applied to ultra-high density magnetic data storage media, biomedical labels, electronics in the nanometer range, energy materials as highly efficient laser beams, and very transparent optical devices

For these broad applications, the method of synthesizing monodisperse nanoparticles with size differences of less than 5% is a key factor in controlling the properties of these base materials, since the properties of these nanoparticles depend mainly on the size of the nanoparticles.

For example, the determining factor for the color sharpness of nanocrystalline optical devices in semiconductors is mainly the uniformity of nanoparticle size, where these monodisperse magnetic nanoparticles are the key base material for ultra-high density magnetic data storage media.

Since these monodisperse nanoparticles can be used in a variety of applications as described above, there is a real need for a method for large-scale production of the base nanoparticle material.

Unfortunately, until now, the synthesis of monodisperse nanoparticles has been limited to levels of the sub-gram order.

Technical scheme

The above-mentioned main object of the present invention is achieved by a method comprising the steps of: i) metal salts dissolved in aqueous solution and salts dissolved in a solvent selected from the group consisting of C_5-10Aliphatic hydrocarbons and C_6-10Alkali metal C of the first solvent of aromatic hydrocarbons_4-25Carboxylate reacting to form a metal carboxylate complex, and ii) heating said metal carboxylate complex dissolved in a second solvent selected from C to obtain nanoparticles_6-25Aromatic compound, C_6-25Ethers, C_6-25Aliphatic hydrocarbons and C_6-25An amine.

According to the invention, the metal salt of the synthetic metal carboxylate complex consists of metal ions and anions, wherein the metal ions are selected from the group consisting of Fe, Co, Ti, V, Cr, Mn, Ni, Cu, Zn, Y, Zr, Mo, Ru, Rh, Pd, Ag, Cd, Ce, Pt, Au, Ba, Sr, Pb, Hg, Al, Ga, In, Sn or Ge; the anion is selected from C_4-25A carboxylic acid.

The metal salt used to prepare the metal carboxylate complex is selected from: hydrated iron chloride (FeCl)₃·6H₂O), ferrous chloride hydrate (FeCl)₂·4H₂O), cobalt chloride hydrate (CoCl)₃·6H₂O), cobalt (II) chloride hydrate (CoCl)₂·4H₂O), chromium chloride hydrate (CrCl)₃·6H₂O), manganese chloride hydrate (MnCl)₂·4H₂O), ferric chloride (FeCl)₃) Ferrous chloride (FeCl)₂) Ferrous bromide (FeBr)₂) Ferrous sulfate (FeSO)₄) Iron nitrate (Fe (NO)₃)₃) Ferrous stearate (Fe (O)₂C₁₈H₃₅)₂) Ferrous acetate (Fe (OOCCH)₃)₂) Cobalt chloride (CoCl)₃) Cobalt (II) chloride (CoCl)₂) Cobalt nitrate (Co (NO)₃)₃) Nickel sulfate (NiSO)₄) Nickel chloride (NiCl)₂) Nickel nitrate (Ni (NO))₃)₂) Titanium tetrachloride (TiCl)₄) Zirconium tetrachloride (ZrCl)₄) Platinum (H) hydrogen hexachloride₂PtCl₆) Palladium (H) hydrogen hexachloride₂PdCl₆) Barium chloride (BaCl)₂) Barium sulfate (BaSO)₄) Strontium chloride (SrCl)₂) Strontium sulfate (SrSO)₄) Zinc acetate (Zn (OOCH)₃)₂) Manganese acetate (Mn (OOCH)₃)₂) Cerium acetate hydrate ((CH)₃COO)₃Ce·xH₂O), cerium bromide hydrate (CeBr)₃·xH₂O), cerium chloride heptahydrate (CeCl)₃·7H₂O), cerium carbonate hydrate (Ce (CO)₃)₃·xH₂O), cerium fluoride hydrate (CeF)₃·xH₂O), Cerium (CH) CH (CH) CO) Ce 2-ethylhexanoate, cerium iodide (CeI)₃) Cerium nitrate hexahydrate (Ce (NO)₃)₃·6H₂O), cerium oxalate hydrate (Ce)₂(C₂O₄)₃·xH₂O), cerium perchlorate (Ce (ClO)₄)₃) Cerium sulfate hydrate (Ce)₂(SO4)₃·xH₂O), iron acetylacetonate (Fe (acac)₃) Cobalt acetylacetonate (Co (acac)₃) Nickel acetylacetonate (Ni (acac)₂) Copper acetylacetonate (Cu (acac)₂) Barium acetylacetonate (Ba (acac)₂) Strontium acetylacetonate (Sr (acac))₂) Acetylacetonato cerium hydrate ((acac)₃Ce·xH₂O), platinum acetylacetonate (Pt (acac)₂) Palladium acetylacetonate (Pd (acac)₂) Titanium tetraisopropoxide (Ti: (a) (b))ⁱOC₃H₇))₄) And zirconium tetrabutyrate (Zr (OC)₄H₉))₄)。

Two or more of the metal salt compounds of the present invention described above are used in the synthesis of monodisperse nanoparticles of multi-metal oxides and alloys.

To form a metal carboxylate complex solution in the second step of the present invention, the metal carboxylate complex is dissolved using the following solvents: ethers, i.e., octyl ether, butyl ether, hexyl ether, benzyl ether, phenyl ether and decyl ether; and aromatic compounds such as toluene, xylene, trimethylbenzene and benzene; and alcohols such as octanol, decanol, n-decanol, ethylene glycol, 1, 2-octanediol, 1, 2-dodecanediol, and 1, 2-hexadecanol; hydrocarbons such as heptane, octane, decane, dodecane, tetradecane, eicosene, octadecene, hexadecene, dimethyl sulfide (DMSO), and dimethyl fluoride (DMF); and alkylamines such as oleylamine, hexadecylamine, trioctylamine, and octylamine.

According to the invention, the metal carboxylate complex solution is heated to between 200 ℃ and the boiling temperature of the second solvent, while the heating rate of the metal carboxylate complex solution is between 1 ℃/minute and 200 ℃/minute.

According to the invention, the metal carboxylate complex solution is aged between 200 ℃ and the boiling temperature of the second solvent, preferably between 300 ℃ and the boiling temperature of the second solvent; the duration is from 1 minute to 24 hours, preferably from 1 minute to 1 hour.

According to the present invention, the size and shape of metal, metal alloy, metal oxide and polymetallic oxide monodisperse nanoparticles are stably controlled by varying reaction parameters such as the amount of reactants, variation of solvent, aging temperature and heating rate.

Furthermore, according to the present invention, the size of the metal, metal alloy, metal oxide and polymetal oxide monodisperse nanoparticles can also be controlled by the ratio of the metal carboxylate complex and the surfactant, wherein the ratio of the metal carboxylate complex and the surfactant ranges from 1: 0.1 to 1: 100, preferably from 1: 0.1 to 1: 20.

According to the present invention, the size of the metal, metal alloy, metal oxide and polymetal oxide monodisperse nanoparticles is further controlled by variation of the second solvent with different boiling point (b.p.). For example, when iron oleate complexes are aged in 1-hexadecene (b.p. ═ 274 ℃), octyl ether (b.p. ═ 287 ℃), 1-octene (b.p. ═ 317 ℃), 1-eicosene (b.p. ═ 330 ℃) and trioctylamine (b.p. ═ 365 ℃) solvents, respectively, monodisperse iron oxide nanoparticles are produced with diameters of approximately 5, 9, 12, 16 and 22nm, respectively.

According to the present invention, metal alloy, metal oxide and polymetallic oxide monodisperse nanoparticles are recovered by adding a flocculant to the solution to precipitate and then centrifuging, wherein the flocculant does not effectively disperse the nanoparticles and does not precipitate the nanoparticles from the solution.

Among the synthesized nanoparticles of the present invention, the magnetic nanoparticles of iron oxide and the nanoparticles of iron have typical superparamagnetic characteristics as shown in fig. 18.

Furthermore, magnetic nanoparticles larger than 16nm in diameter have ferromagnetism or ferrimagnetism at room temperature with a magnetic moment sufficient for magnetic data storage media, and thus have many potential uses in industrial applications.

Advantageous effects

The present invention discloses a method for large scale production of uniform metal, metal alloy, metal oxide and polymetallic oxide monodisperse nanoparticles without size selection process, wherein the nanoparticles are substantially uniform in size and shape, such that the uniform nanoparticles obtained have the properties required for the aforementioned applications.

The main object of the present invention is to provide a simple and environmentally friendly method for producing monodisperse nanoparticles of metals, metal alloys, metal oxides and multimetal oxides, wherein the production scale of the nanoparticles is about 100 grams.

The nanoparticles prepared by the method of the present invention are redispersed in different solvents without aggregation; moreover, since the uniformity of size and shape allows the nanoparticles to form a superlattice by self-assembly, the nanoparticles can be assembled in a wide range of ordered 2-or 3-dimensional superlattices by slow evaporation.

Nanoparticles synthesized according to the present invention can be used in the terabit/in range²High density magnetic storage devices may also be used in biomedical applications, such as contrast agents for Magnetic Resonance Imaging (MRI), and in Drug Delivery Systems (DDS).

Drawings

The advantages and objects of the present invention will become more apparent from the following description of the embodiments and the accompanying drawings. The drawings are illustrated as follows:

figure 1 is a FT-IR spectrum of an iron oleate complex according to the invention (solid curve) and of this complex after heating at 380 ℃ (dashed curve), the spectrum showing the formation of iron oxide.

Fig. 2 is a TEM picture of a mass synthesized spherical iron oxide nanoparticle with a diameter of 12nm according to example 2. The upper right panel shows a photograph of 40 grams of monodisperse iron oxide nanoparticles on a Petri dish.

Fig. 3a, 3b, 3c, 3d, 3e are high resolution tem (hrtem) pictures of iron oxide nanoparticles of different diameters (a)5nm, (b)9nm, (c)12nm, (d)16nm and (e)22nm synthesized according to examples 3, 4, 2, 5 and 6, respectively.

The two diagrams in FIG. 4 show the L of Fe_2，3Side X-ray absorption spectrum (XAS) (left side) and X-ray magnetic circular dichroism (XMCD) spectra (right side) of iron oxide nanoparticles synthesized according to examples 3, 4, 2, 5 and 6 and having diameters of 5nm, 9nm, 12nm, 16nm and 22nm, respectively; wherein, for comparison, the reference phase material gamma-Fe is shown₂O₃And Fe₃O₄XAS and XMCD spectra of (a). In the small picture of FIG. 4, the enlarged XA of L region is shown respectivelyS spectra and XMCD spectra of nanoparticles with diameters of 5nm and 22 nm.

Figure 5 is a powder X-ray diffraction pattern (XRD) of spherical iron oxide nanoparticles of 12nm diameter synthesized according to example 2.

FIG. 6 is a TEM image of a mass-synthesized spherical iron oxide nanoparticle with a diameter of 5nm according to example 3.

FIG. 7 is a TEM image of a mass-synthesized spherical iron oxide nanoparticle with a diameter of 9nm according to example 4.

FIG. 8 is a TEM image of a mass-synthesized spherical iron oxide nanoparticle with a diameter of 16nm according to example 5.

FIG. 9 is a TEM image of a mass-synthesized spherical iron oxide nanoparticle with a diameter of 22nm according to example 6.

Fig. 10 is a TEM image of cubic manganese oxide nanoparticles having a diameter of 12nm, in which top and bottom side small images respectively show an electron diffraction pattern and a high resolution TEM image of MnO nanoparticles synthesized according to example 7.

FIG. 11 is a powder X-ray diffraction pattern (XRD) of cubic manganese oxide nanoparticles of 12nm diameter synthesized according to example 7.

The upper left side of fig. 12 shows a TEM image of pencil-shaped cobalt oxide (CoO) nanoparticles synthesized according to example 8; the upper right and middle panels show the electron diffraction pattern and schematic model of the same nanoparticles, respectively. The lower left and lower right sides show high resolution TEM images of the <002> and <100> directions, respectively.

FIG. 13 shows a powder X-ray diffraction pattern (XRD) of pencil-shaped cobalt oxide (CoO) nanoparticles synthesized according to example 8.

Fig. 14 is a TEM image of a cubic iron (Fe) nanoparticle synthesized according to example 9 with a diameter of 20nm, and upper right and lower right minigrams are an electron diffraction pattern and a high resolution TEM image, respectively, of the same iron nanoparticle.

FIG. 15 is a powder X-ray diffraction pattern (XRD) of 20nm diameter cubic iron (Fe) nanoparticles synthesized according to example 9.

FIG. 16 shows spherical 8nm diameter cobalt ferrite (CoFe) synthesized according to example 10₂O₄) TEM images of nanoparticles.

FIG. 17 shows spherical manganese ferrite (MnFe) of 9nm in diameter synthesized according to example 11₂O₄) TEM images of nanoparticles.

Fig. 18 is a graph of magnetic properties versus temperature for spherical iron oxide nanoparticles 5, 9, 12, 16 and 22nm in diameter after a zero field cooling process, wherein spherical iron oxide nanoparticles 5, 9, 12, 16 and 22nm in diameter were synthesized according to examples 3, 4, 2, 5, 6, respectively.

Fig. 19 is a TEM image of spherical zinc oxide (ZnO) nanoparticles of 5nm diameter synthesized according to example 13.

FIG. 20 is a 2nm diameter spherical cerium oxide (CeO) synthesized according to example 14₂) TEM images of nanoparticles.

Detailed Description

The following describes the implementation of the present invention and the corresponding preferred embodiments. However, the implementations and methods described herein are merely specific illustrations of the invention. The following examples and specific embodiments are not intended to limit the present invention. Any obvious changes or modifications which are obvious to those skilled in the art are included in the technical solution of the present invention and the protection of the claims.

Example 1: synthesis of iron oleate complexes

A method of synthesizing monodisperse nanoparticles is demonstrated as a first embodiment of the invention. 10.8 grams of ferric chloride (FeCl)₃-6H₂O, 40mmol) and 36.5 g of sodium oleate (120mmol) are dissolved in 60ml of distilled water containing 80ml of ethanolWater and 140ml hexane, the mixture was heated to 70 ℃ and held for 4 hours to give iron-oleate complex. During this process, the scarlet liquid phase became clear and the transparent organic phase changed to scarlet, indicating the successful synthesis of the iron-oleate complex. When the reaction was completed, the upper organic layer containing the metal-oleate complex was separated, and then hexane was evaporated to give a waxy solid. In FIG. 1, the FT-IR spectrum of the iron-oleate complex obtained shows a stretching peak (stretching peak) at 1700cm for C ═ O^-1This is a unique feature of metal-oleate complexes.

Example 2: mass synthesis of monodisperse and spherical iron oxide nanoparticles- (A)

This example discloses the bulk synthesis of monodisperse and spherical iron oxide nanoparticles of the present invention. 36 g of iron oleate complex synthesized according to example 1 were added to a mixture containing 200 g of dehydrated octene and 5.7 g of oleic acid at room temperature under an inert atmosphere.

The resulting mixture was heated to 320 ℃ and then held at that temperature for 30 minutes of aging during which time a strong reaction occurred and the initially clear solution turned brownish black, indicating complete decomposition of the iron oleate complex and formation of iron oxide nanoparticles.

The solution containing the nanoparticles was cooled to room temperature, and an excess of ethanol was added to produce a black precipitate, which was then separated by centrifugation.

Then, the supernatant was removed. This washing process was performed at least three times, and then ethanol was removed from the residue by vacuum drying.

The resulting product is easily redispersed again in ethane to form the desired iron nanoparticles. The observations and data analysis of iron nanoparticles 12nm in diameter are listed below

Fig. 2 shows a TEM (transmission electron microscope) picture of the obtained iron nanoparticles, which is a TEM picture of spherical iron oxide nanoparticles having a diameter of 12nm, wherein the picture shows that the obtained nanoparticles are spherical and the particle size is monodisperse.

FIG. 3c shows a High Resolution Transmission Electron Microscope (HRTEM) of monodisperse spherical iron oxide (magnetite) nanoparticles with a diameter of 12nm, indicating that the resulting nanoparticles are highly crystallized.

FIG. 4 shows XAS (left) and XMCD (right) spectra of iron oxide 12nm in diameter, and two reference phase materials γ -Fe for comparison₂O₃And Fe₃O₄XAS and XMCD spectra of (a); it is almost identical to the spinel lattice structure of the reference material in terms of lattice constant, with a difference of about 1%. Results from XAS and XMCD data for (gamma-Fe)₂O₃)1-x(Fe₃O₄)_xQuantitative calculations were made for the composition of the iron oxide nanoparticles in the form in which the diameter of the nanoparticles was 12nm when x is 0.68.

FIG. 5 shows the powder X-ray diffraction pattern (XRD) of spherical iron oxide nanoparticles of 12nm diameter synthesized according to example 2, in which magnetite (Fe) is obtained₃O₄) The XRD pattern of the nanoparticles indicates that the nanoparticles are highly crystallized.

Example 3: mass synthesis of monodisperse and spherical iron oxide nanoparticles- (B)

According to the invention, a method analogous to example 2 above was carried out in order to synthesize monodisperse and spherical iron oxide nanoparticles having a diameter of 5 nm: 18 g of iron oleate complex are added to a mixture containing 100 g of dehydrated octene and 5.7 g of oleic acid under an inert atmosphere; the resulting mixture was heated to 280 ℃ and then aged at reflux temperature for 1 hour, thereby forming colloidal iron oxide nanoparticles having a diameter of 5 nm. The resulting solution was cooled to room temperature.

Then, ethanol was added to wash the precipitate to obtain a black precipitate, followed by centrifugation at 2000 rpm to recover the precipitated nanoparticles. Thereafter, this washing was repeated at least three times, and vacuum drying was performed to remove ethanol, to obtain desired spherical iron oxide nanoparticles. The resulting nanoparticles are readily re-dispersed in non-polar organic solvents such as ethane or toluene.

Fig. 6 shows TEM images of the obtained nanoparticles, confirming that spherical iron oxide nanoparticles having a diameter of 5nm synthesized in large quantities according to example 3 are monodisperse according to particle size.

The High Resolution Transmission Electron Microscopy (HRTEM) picture of a 5nm diameter monodisperse iron oxide (iron ore) nanoparticle shown in fig. 3a shows that the nanoparticle is highly crystalline.

FIG. 4 shows XAS (left) and XMCD (right) spectra of iron oxide with a diameter of 5nm, and two reference phase materials γ -Fe for comparison₂O₃And Fe₃O₄XAS and XMCD spectra of (a); from the lattice constants, the curve shows that the spinel lattice structures of the resulting nanoparticles and the reference material therein are almost identical, with a difference of about 1%.

XAS and XMCD spectra of nanoparticles 5nm in diameter and Fe-only³⁺gamma-Fe of₂O₃Similarly. (γ -Fe) obtained according to XAS and XMCD data₂O₃)_1-x(Fe₃O₄)_xQuantitative calculations were made for the composition of the iron oxide nanoparticles in the form in which the diameter of the nanoparticles was 5nm when x is 0.20. It can therefore be concluded that gamma-Fe₂O₃The phase is the main phase of iron oxide nanoparticles with a diameter of 5 nm.

Example 4: mass synthesis of monodisperse and spherical iron oxide nanoparticles- (C)

Monodisperse spherical iron oxide nanoparticles with a diameter of 9nm were synthesized using the reaction conditions described above in example 3, except that the solvent was replaced with octyl ether and the final aging temperature was 300 ℃.

A TEM picture of the resulting monodisperse spherical iron oxide nanoparticles with a diameter of 9nm is shown in fig. 7, which shows that the particle size of the spherical iron oxide nanoparticles is monodisperse.

The High Resolution Transmission Electron Microscopy (HRTEM) picture of 9nm diameter monodisperse spherical iron oxide (iron ore) nanoparticles shown in fig. 3b indicates that the nanoparticles are highly crystalline.

FIG. 4 shows XAS (left) and XMCD (right) spectra of iron oxide nanoparticles 9nm in diameter, and two reference phase materials γ -Fe for comparison₂O₃And Fe₃O₄XAS and XMCD spectra of (a); the curve shows that the spinel lattice structures of the resulting nanoparticles and the reference material therein are almost identical, differing by about 1%, in terms of the cubic lattice constant. (γ -Fe) obtained according to XAS and XMCD data₂O₃)_1-x(Fe₃O₄)_xQuantitative calculations were made for the composition of the iron oxide nanoparticles in the form in which the diameter of the nanoparticles was 9nm when x is 0.57.

Example 5: mass synthesis of monodisperse and spherical iron oxide nanoparticles- (D)

Monodisperse spherical iron oxide nanoparticles of 16nm diameter were synthesized using the reaction conditions described above in example 3, except that the solvent was replaced with eicosene and the final aging temperature was 330 ℃.

A TEM picture of the resulting monodisperse spherical iron oxide nanoparticles with a diameter of 16nm is shown in fig. 8, which shows that the particle size of the spherical iron oxide nanoparticles with a diameter of 16nm is monodisperse.

The High Resolution Transmission Electron Microscopy (HRTEM) picture of monodisperse spherical iron oxide (iron ore) nanoparticles with a diameter of 16nm shown in fig. 3d shows that the nanoparticles are highly cross-crystalline in the nanostructure.

FIG. 4 shows XAS (left) and XMCD (right) spectra of iron oxide nanoparticles 16nm in diameter, and two reference phase materials γ -Fe for comparison₂O₃And Fe₃O₄XAS and XMCD spectra of (a); the curve shows the resulting spinel of nanoparticles and reference material therein in terms of cubic lattice constantThe stone lattice structures are almost identical, with a difference of about 1%. (γ -Fe) obtained according to XAS and XMCD data₂O₃)_1-x(Fe₃O₄)_xQuantitative calculations were made for the composition of the iron oxide nanoparticles in the form in which the synthesized nanoparticles had a diameter of 16nm when x was 0.86.

Example 6: mass synthesis of monodisperse and spherical iron oxide nanoparticles- (E)

Monodisperse spherical iron oxide nanoparticles 22nm in diameter were synthesized using the reaction conditions described above in example 3, except that the solvent was replaced with trioctylamine and the final aging temperature was 360 ℃.

A TEM picture of the resulting monodisperse spherical iron oxide nanoparticles with a diameter of 22nm is shown in fig. 9, which shows that the particle size of the spherical iron oxide nanoparticles with a diameter of 22nm is monodisperse.

The High Resolution Transmission Electron Microscopy (HRTEM) picture of monodisperse spherical iron oxide (iron ore) nanoparticles with a diameter of 22nm shown in fig. 3e shows that the nanoparticles are highly cross-crystalline in the nanostructure.

FIG. 4 shows XAS and XMCD spectra of iron oxide nanoparticles 22nm in diameter, and two reference phase materials γ -Fe for comparison₂O₃And Fe₃O₄XAS and XMCD spectra of (a); the curve shows that the spinel lattice structures of the resulting nanoparticles and the reference material therein are almost identical, differing by about 1%, in terms of the cubic lattice constant. (γ -Fe) obtained according to XAS and XMCD data₂O₃)_1-x(Fe₃O₄)_xQuantitative calculations were made for the composition of the form of iron oxide nanoparticles, where the diameter of the synthesized nanoparticles was 22nm when x ═ 1.00, thus indicating that the synthesized nanoparticles of 22nm were of pure magnetite.

Example 7: synthesis of monodisperse manganese oxide nanoparticles

Monodisperse, cubic manganese oxide (MnO) nanoparticles of 12nm diameter were synthesized according to the present invention using a similar method as described in example 2 above; to a solution containing 10 grams of dehydrated 1-octene was added 1.24 grams of manganese oleate under an inert atmosphere, and the resulting mixture was heated to 320 ℃ and aged at reflux temperature for 1 hour to form brownish black colloidal manganese nanoparticles.

Fig. 10 shows TEM pictures of cubic manganese oxide nanoparticles synthesized according to the present invention at 12nm, showing that the diameter of the nanoparticles is very uniform.

FIG. 11 is a powder X-ray diffraction pattern (XRD) of cubic manganese oxide nanoparticles 12nm in diameter illustrating the synthesis of face centered cubic (fcc) MnO nanoparticles using the method of example 7 below.

Example 8: synthesis of monodisperse cobalt oxide (CoO) nanoparticles

According to the present invention, cobalt oxide (CoO) nanoparticles in the form of bullets were synthesized using a method similar to that described above in example 2; 1.25 grams of cobalt oleate were added to a solution containing 10 grams of dehydrated 1-octene under an inert atmosphere, and the resulting mixture was heated to 320 ℃ and aged at reflux temperature for 1 hour to form gray-brown colloidal cobalt oxide nanoparticles. For cobalt oxide, it is known that it has intrinsic crystal anisotropy, and cobalt oxide nanoparticles preferably grow along the c-axis.

A TEM image of the bullet shaped cobalt oxide (CoO) nanoparticles synthesized according to the present invention and their 2-dimensional arrangement are shown in fig. 12. The TEM picture in fig. 12 reveals that the cobalt oxide nanoparticles in bullet form are monodisperse and form a honeycomb and self-assembled superlattice structure. Meanwhile, the upper right panel of fig. 12 shows the crystal structure of wurtzite of the synthesized cobalt oxide nanoparticles in the form of warheads. In addition, a High Resolution Transmission Electron Microscope (HRTEM) image of the bullet-shaped cobalt oxide nanoparticles at the lower side of fig. 12 shows that the nanoparticles are highly crystalline.

FIG. 13 shows the powder X-ray diffraction pattern (XRD) of the pencil-lead cobalt oxide (CoO) nanoparticles, which also show that the cobalt oxide nanoparticles have a wurtzite structure similar to ZnO.

Example 9: synthesis of monodisperse iron nanoparticles

Monodisperse, cuboidal, 20 nm-sized iron nanoparticles according to the invention were synthesized using a method analogous to that described in example 2 above; 1.24 grams of iron oleate complex was added to 50ml of a solution containing 5 grams of dehydrated oleic acid in a round bottom flask under an inert atmosphere, and the resulting mixture was heated to 370 ℃ and aged at the same temperature for 1 hour to form black colloidal iron nanoparticles. It is noted that when thermal decomposition of the iron oleate complex occurs at the higher temperature of 350 ℃, the nanoparticles self-reduce to iron, as is the case in the present invention.

A TEM picture of cubic 20nm iron nanoparticles synthesized according to the invention is illustrated in fig. 14, which shows that the diameter of the nanoparticles is very uniform.

The electron diffraction pattern shown in the upper right hand panel of fig. 14 shows that the synthesized 20nm iron nanoparticles have a body-centered cubic (bcc) crystal structure. In addition, a High Resolution Transmission Electron Microscopy (HRTEM) picture of 20nm iron nanoparticles shown in the lower right panel of fig. 14 shows that the resulting nanoparticles are highly crystalline, with the 20nm size iron nanoparticle surface passivated by a thin layer of FeO.

FIG. 15 is a powder X-ray diffraction (XRD) pattern of 20nm cubic iron nanoparticles showing that the highly crystalline body-centered cubic (bcc) iron core is passivated by a thin layer of FeO on the surface.

Example 10: monodisperse spherical cobalt ferrite (CoFe)₂O₄) Synthesis of nanoparticles

5.4 g of FeCl were synthesized according to the method of example 1 above₃-6H₂O, 2.4 g CoCl₃-6H₂O with 24.36 g of sodium oleate in a mixture comprising 40ml of ethanol, 30ml of water and 70ml of hexane, 1.22 g of iron/cobalt oleate complex synthesized by reaction, is added under inert atmosphere to a solvent comprising 10 g of dehydrated 1-octene, the mixture obtainedThe contents were heated to 320 ℃ and held at this temperature for 30 minutes.

In this process, the precursor is completely pyrolyzed to form the bimetallic ferrite nanoparticles. The solution was then cooled to room temperature. To remove excess surfactant and by-products, anhydrous degassed ethanol was added to produce a brownish black precipitate and the supernatant removed by decantation or centrifugation. This washing was then repeated three or more times to remove the ethanol by vacuum drying. The obtained spherical cobalt ferrite (CoFe) with the diameter of 8nm₂O₄) The nanoparticles were readily re-dispersed in hexane.

TEM pictures of cobalt ferrite nanoparticles synthesized according to this method, shown in FIG. 16, show spherical cobalt ferrite (CoFe) with a diameter of 8nm₂O₄) The nanoparticles are monodisperse.

Example 11: monodisperse spherical manganese ferrite (MnFe)₂O₄) Synthesis of nanoparticles

Synthesis of monodisperse spherical manganese ferrite (MnFe) under similar conditions to those in example 10₂O₄) A nanoparticle; 1.8 g of iron oleate and 0.62 g of manganese oleate are added under inert atmosphere to a solvent containing 10 g of dehydrated 1-octene, and the resulting mixture is heated to 320 ℃ and maintained at this temperature for 30 minutes. Through the same cleaning process as in example 9, spherical manganese ferrite (MnFe) having a diameter of 9nm was synthesized₂O₄) And (3) nanoparticles.

FIG. 17 shows a manganese ferrite (MnFe) synthesized according to this method₂O₄) TEM pictures of nanoparticles show spherical manganese ferrites (MnFe) with a diameter of 9nm₂O₄) The nanoparticles are monodisperse.

Example 12: magnetic properties of spherical iron oxide nanoparticles

After Zero Field Cooling (ZFC) of spherical iron oxide nanoparticles of 5, 9, 12, 16 and 22nm diameter synthesized according to examples 3, 4, 2, 5, 6 with 1000e between 5 and 380K, the relationship between temperature and magnetism was determined with a superconducting quantum interferometer (SQUID).

Fig. 18 shows the relationship between magnetism and temperature across ZFC, much like that of the spherical iron oxide nanoparticles of 5, 9, 12, 16 and 22 nm. The curves of fig. 18 show that the cut-off Temperatures (TB) of spherical iron oxide nanoparticles with diameters of 5, 9, 12, 16 and 22nm are 30, 80, 125, 230 and 260K, respectively. All iron oxide samples showed superparamagnetism above the cut-off temperature, with the TB increasing continuously with increasing nanoparticles.

Example 13: synthesis of monodisperse spherical zinc oxide (ZnO) nanoparticles

Following the synthesis of example 1 above, 5.45 grams of ZnCl were added₂12 g of a zinc oleate complex synthesized by reaction with 24.36 g of sodium oleate in a mixture comprising 40ml of ethanol, 30ml of water and 70ml of hexane are added to 60 g of TOPO in a stabilizing coordinating solvent (stabilizing coordinating solvent) under an inert atmosphere, and the resulting mixture is heated to 330 ℃ and maintained at this temperature for 1 hour.

In this process, the precursor is completely thermally decomposed to form zinc oxide nanoparticles. The solution was then cooled to room temperature. To remove excess surfactant and by-products, anhydrous degassed ethanol was added to produce a white precipitate and the supernatant removed by decantation or centrifugation. This washing was then repeated three or more times to remove the ethanol by vacuum drying. The obtained zinc oxide nanoparticles with a diameter of 5nm were easily re-dispersed in hexane.

The TEM picture of zinc oxide nanoparticles synthesized according to example 13 shown in fig. 19 shows that spherical ZnO nanoparticles having a diameter of 5nm are monodisperse.

Example 14: monodisperse spherical cerium oxide (CeO)₂) Synthesis of nanoparticles

Following the synthesis of example 1 above, 7.45 g of CeCl were added₃-7H₂20 g of cerium oleate complex synthesized by reaction of O with 18.27 g of sodium oleate in a mixture comprising 40ml of ethanol, 30ml of water and 70ml of hexane, are added under an inert atmosphereInto 200ml of oleylamine stabilizing and adjusting solvent, and the resulting mixture was heated to 320 ℃ and maintained at this temperature for 2 hours.

In this process, the precursor is completely thermally decomposed to form cerium oxide nanoparticles. The solution was then cooled to room temperature. To remove excess surfactant and by-products, anhydrous degassed ethanol was added to produce a white precipitate and the supernatant removed by decantation or centrifugation. This washing was then repeated three or more times to remove the ethanol by vacuum drying. The resulting ceria nanoparticles with a diameter of 2nm were easily re-dispersed in hexane.

The TEM picture of the cerium oxide nanoparticles synthesized according to example 14 shown in fig. 20 indicates that spherical cerium oxide nanoparticles having a diameter of 2nm are monodisperse.

MODE OF THE INVENTION

According to the present invention, metal alloy, metal oxide and polymetallic oxide monodisperse nanoparticles having excellent magnetic properties for magnetic data storage media, which are confirmed by testing the temperature and magnetic relationships of the synthesized metal oxide nanoparticles of different sizes, are synthesized in large quantities.

Industrial applicability

Recently, the development of monodisperse and highly crystalline metal, metal alloy, metal oxide and multi-metal oxide nanoparticles has been of great positive significance not only in scientific research, but also in practical and potential applications in many fields including ultra-high density magnetic data storage media, biomedical marking agents, drug delivery substances, nanoscale electronics, high efficiency laser beam sources, highly transparent optical devices and MRI enhancing agents. The conventional synthesis method is not suitable for large-scale and low-cost production, and thus cannot be well adapted to industrial application.

The synthetic methods disclosed herein have the advantages of simplicity, low cost, non-toxicity, and environmental friendliness, and are unique for the large scale synthesis of the desired monodisperse, highly crystalline nanoparticles. Thus, the synthetic methods disclosed herein are beneficial in the following potential application areas: ultra-high density magnetic data storage media, biomedical identification agents, drug targeting substances, nanoscale electronics, high efficiency laser beam sources, highly transparent optical devices, and MRI enhancement agents.

Sequence listing

None.

Claims (11)

1. A method of making metal, metal alloy, metal oxide and multi-metal oxide nanoparticles, the method comprising the steps of:

i) metal salts dissolved in aqueous solution and salts dissolved in a solvent selected from the group consisting of C_5-10Aliphatic hydrocarbons and C_6-10Alkali metal C of the first solvent of aromatic hydrocarbon_4-25Carboxylate salt reaction to form a metal carboxylate salt complex, and

ii) heating said metal carboxylate complex dissolved in a second solvent selected from C_6-25Aromatic compound, C_6-25Ethers, C_6-25Aliphatic hydrocarbons and C_6-25An amine at a temperature of from room temperature to a temperature between 200 ℃ and the boiling temperature of the second solvent at a heating rate of from 1 ℃/minute to 200 ℃/minute such that the metal carboxylate complex thermally decomposes to produce nanoparticles.

2. The method of claim 1, wherein the metal is selected from the group consisting of Fe, Co, Ti, V, Cr, Mn, Ni, Cu, Zn, Y, Zr, Mo, Ru, Rh, Pd, Ag, Cd, Ce, Pt, Au, Ba, Sr, Pb, Hg, Al, Ga, In, Sn and Ge; the alkali metal is selected from Li, Na and K.

3. The method of claim 1, wherein the metal salt is selected from the group consisting of ferric chloride (FeCl)₃) Ferrous chloride (FeCl)₂) Ferrous bromide (FeBr)₂) Ferrous sulfate (FeSO)₄) Iron nitrate (Fe (NO)₃)₃) Ferrous stearate (Fe (O)₂C₁₈H₃₅)₂) Ferrous acetate (Fe (OOCCH)₃）₂) Cobalt chloride (CoCl)₃) Cobalt (II) chloride (CoCl)₂) Cobalt nitrate (Co (NO)₃)₃) Nickel sulfate (NiSO)₄) Nickel chloride (NiCl)₂) Nickel nitrate (Ni (NO))₃)₂) Titanium tetrachloride (TiCl)₄) Zirconium tetrachloride (ZrCl)₄) Platinum (H) hydrogen hexachloride₂PtCl₆) Palladium (H) hydrogen hexachloride₂PdCl₆) Barium chloride (BaCl)₂) Barium sulfate (BaSO)₄) Strontium chloride (SrCl)₂) Strontium sulfate (SrSO)₄) Zinc acetate (Zn (OOCH)₃)₂) Manganese acetate (Mn (OOCH)₃)₂) Cerium acetate hydrate ((CH)₃COO)₃Ce·xH₂O), cerium bromide hydrate (CeBr)₃·xH₂O), cerium chloride heptahydrate (CeCl)₃·7H₂O), cerium carbonate hydrate (Ce (CO)₃)₃·xH₂O), cerium fluoride hydrate (CeF)₃·xH₂O), 2-ethylhexylCerium acid (CH) CH (CH) CO) Ce), cerium iodide (CeI)₃) Cerium nitrate hexahydrate (Ce (NO)₃)₃·6H₂O), cerium oxalate hydrate (Ce)₂(C₂O₄)₃·xH₂O), cerium perchlorate (Ce (ClO)₄)₃) Cerium sulfate hydrate (Ce)₂(SO₄)₃·xH₂O), iron acetylacetonate (Fe (acac)₃) Cobalt acetylacetonate (Co (acac)₃) Nickel acetylacetonate (Ni (acac)₂) Copper acetylacetonate (Cu (acac)₂) Barium acetylacetonate (Ba (acac)₂) Strontium acetylacetonate (Sr (acac))₂) Acetylacetonato cerium hydrate ((acac)₃Ce·xH₂O), platinum acetylacetonate (Pt (acac)₂) Palladium acetylacetonate (Pd (acac)₂) Titanium tetraisopropoxide (Ti: (a) (b))ⁱOC₃H₇)）₄) And zirconium tetrabutyrate (Zr (OC)₄H₉)）₄）。

4. The method of claim 1, wherein the metal salt is selected from the group consisting of hydrated iron chloride (FeCl)₃·6H₂O), ferrous chloride hydrate (FeCl)₂·4H₂O), cobalt chloride hydrate (CoCl)₃·6H₂O), cobalt (II) chloride hydrate (CoCl)₂·4H₂O), chromium chloride hydrate (CrCl)₃·6H₂O), manganese chloride hydrate (MnCl)₂·4H₂O）。

5. The method of claim 1, wherein the alkali metal C is_4-25The carboxylate is selected from sodium oleate, sodium stearate, sodium laurate, potassium oleate, potassium stearate, potassium laurate, Sodium Dodecyl Sulfate (SDS), and sodium dodecylbenzene chloride (DBS).

6. The process of claim 1 wherein said first solvent is selected from the group consisting of hexane, heptane, pentane, octane, xylene, toluene, and benzene.

7. The method of claim 1, wherein the second solvent is selected from the group consisting of decane, eicosane, hexadecane, eicosene, phenanthrene, pentacene, anthracene, biphenyl, dimethylbiphenyl, phenylene ether, octyl ether, decyl ether, benzyl ether, trioctylamine, hexadecylamine, and octadecylamine.

8. The method of claim 1, wherein, prior to performing step ii), C_4-25The carboxylic acid is added to the metal carboxylate complex dissolved in a second solvent.

9. The method of claim 8, wherein said C_4-25The carboxylic acid is selected from oleic acid, stearic acid, lauric acid, palmitic acid, caprylic acid and capric acid.

10. The method of claim 1, wherein the aqueous solution further comprises ethanol and/or methanol.

11. The method of claim 1, wherein the temperature is maintained for 1 minute to 24 hours.