U.S. patent application number 12/342979 was filed with the patent office on 2010-02-11 for method for preparing nickel nanoparticles.
This patent application is currently assigned to SAMSUNG ELECTRO-MECHANICS CO., LTD.. Invention is credited to Ae Sul Im, Kyung Mi Kim, Jae Joon Lee, Hyo Seung Nam, Jung Wook Seo.
Application Number | 20100031775 12/342979 |
Document ID | / |
Family ID | 41651698 |
Filed Date | 2010-02-11 |
United States Patent
Application |
20100031775 |
Kind Code |
A1 |
Seo; Jung Wook ; et
al. |
February 11, 2010 |
METHOD FOR PREPARING NICKEL NANOPARTICLES
Abstract
Provided is a method for preparing nickel nanoparticles capable
of easily controlling particle sizes and shapes of the nickel
nanoparticles and obtaining a high yield of the nickel
nanoparticles using a process that is simpler than methods used to
mass-produce the nickel nanoparticles. The method for preparing
nickel nanoparticles may be useful to prepare nickel nanoparticles
by mixing a nickel precursor and organic amine to prepare a mixture
and heating the mixture.
Inventors: |
Seo; Jung Wook; (Hwaseong,
KR) ; Nam; Hyo Seung; (Yongin, KR) ; Im; Ae
Sul; (Suwon, KR) ; Kim; Kyung Mi; (Suwon,
KR) ; Lee; Jae Joon; (Seoul, KR) |
Correspondence
Address: |
MCDERMOTT WILL & EMERY LLP
600 13TH STREET, N.W.
WASHINGTON
DC
20005-3096
US
|
Assignee: |
SAMSUNG ELECTRO-MECHANICS CO.,
LTD.
|
Family ID: |
41651698 |
Appl. No.: |
12/342979 |
Filed: |
December 23, 2008 |
Current U.S.
Class: |
75/364 ;
75/374 |
Current CPC
Class: |
C30B 7/14 20130101; C30B
29/02 20130101; C30B 29/60 20130101; B22F 2998/00 20130101; B22F
9/24 20130101; B22F 1/0018 20130101; B22F 2998/00 20130101 |
Class at
Publication: |
75/364 ;
75/374 |
International
Class: |
B22F 9/18 20060101
B22F009/18 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 5, 2008 |
KR |
10-2008-0076448 |
Claims
1. A method for preparing nickel nanoparticles, comprising: mixing
a nickel precursor, organic amine and a reducing agent to prepare a
mixture; and heating the mixture.
2. The method of claim 1, wherein an organic solvent is further
mixed with the mixture.
3. The method of claim 1, wherein the nickel precursor is at least
one selected from the group consisting of nickel chloride
(NiCl.sub.2), nickel sulfate (NiSO.sub.4), nickel acetate
(Ni(OCOCH.sub.3).sub.2), nickel acetylacetonate
(Ni(C.sub.5H.sub.7O.sub.2).sub.2), halogenated nickel (NiX.sub.2,
wherein X is F, Br, or I), nickel carbonate (NiCO.sub.3), nickel
cyclohexanebutyrate
([C.sub.6H.sub.11(CH.sub.2).sub.3CO.sub.2].sub.2Ni), nickel nitrate
(Ni(NO.sub.3).sub.2), nickel oxalate (NiC.sub.2O.sub.4), nickel
stearate (Ni(H.sub.3C(CH.sub.2).sub.16CO.sub.2).sub.2), nickel
octanoate ([CH.sub.3(CH.sub.2).sub.6CO.sub.2].sub.2Ni) and hydrates
thereof.
4. The method of claim 1, wherein the organic amine is presented by
C.sub.nNH.sub.2 (wherein, n is an integer of
4.ltoreq.n.ltoreq.30).
5. The method of claim 1, wherein the organic amine comprises at
least one selected from the group consisting of oleyl amine,
dodecyl amine, lauryl amine, octyl amine, trioctyl amine, dioctyl
amine and hexadecyl amine.
6. The method of claim 1, wherein the reducing agent comprises at
least one selected from the group consisting of sodium borohydride
(NaBH.sub.4), tetrabutylammonium borohydride
((CH.sub.3CH.sub.2CH.sub.2CH.sub.2).sub.4N(BH.sub.4)), lithium
aluminumhydride (LiAlH.sub.4), sodium hydride (NaH),
borane-dimethylamine complex((CH.sub.3).sub.2NH.BH.sub.3) and
alkanediol (HO(CH.sub.2).sub.nOH, wherein n is an integer of
5.ltoreq.n.ltoreq.30).
7. The method of claim 2, wherein the organic solvent comprises at
least one selected from the group consisting of an ether-based
organic solvent (C.sub.nOC.sub.n, wherein n is an integer of
4.ltoreq.n.ltoreq.30), a saturated hydrocarbon-based organic
solvent (C.sub.nH.sub.2n+2, wherein n is an integer of
7.ltoreq.n.ltoreq.30), an unsaturated hydrocarbon-based organic
solvent (C.sub.nH.sub.2n, wherein n is an integer of
7.ltoreq.n.ltoreq.30), and an organic acid-based organic solvent
(C.sub.nCOOH, wherein n is an integer of 5.ltoreq.n.ltoreq.30).
8. The method of claim 7, wherein the ether-based organic solvent
is at least one selected from the group consisting of
trioctylphosphine oxide, alkyl phosphine, octyl ether, benzyl
ether, and phenyl ether.
9. The method of claim 7, wherein the saturated hydrocarbon-based
organic solvent is at least one selected from the group consisting
of hexadecane, heptadecane and octadecane.
10. The method of claim 7, wherein the unsaturated
hydrocarbon-based organic solvent is at least one selected from the
group consisting of octene, heptadecene and octadecene.
11. The method of claim 7, wherein the organic acid-based organic
solvent is at least one selected from the group consisting of oleic
acid, lauric acid, stearic acid, mysteric acid and hexadecanoic
acid.
12. The method of claim 1, wherein the operation of heating the
mixture is performed at a temperature of 50 to 450.degree. C.
13. The method of claim 1, wherein the operation of heating the
mixture is performed for 1 minute to 8 hours.
14. The method of claim 1, further comprising: separating the
nickel nanoparticles from the heated mixture.
15. The method of claim 14, wherein the operation of separating the
nickel nanoparticles from the heated mixture comprises: adding
ethanol or acetone to the heated mixture to precipitate the nickel
nanoparticles.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the priority of Korean Patent
Application No. 2008-76448 filed on Aug. 5, 2008, in the Korean
Intellectual Property Office, the disclosure of which is
incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a method for preparing
nickel nanoparticles, and more particularly, to a method for
preparing nickel nanoparticles capable of easily controlling
particle sizes and shapes of the nickel nanoparticles and obtaining
a high yield of nickel nanoparticles using a process that is
simpler than methods used to mass-produce the nickel
nanoparticles.
[0004] 2. Description of the Related Art
[0005] Nickel may be used as an electrode material, or a catalyst
of a fuel cell, a catalyst in hydrogenation or a catalyst in
various chemical reactions in the field of a variety of
applications. For example, nickel has been used as an internal
electrode material of a multi-layer ceramic capacitor (MLCC), or a
material to improve loading density. Also, nickel has been used as
a catalyst in the field of a fuel cell and organic synthesis, and
there have been ardent attempts to develop nickel particles as an
alternative to noble metals such as platinum. With the recent
tendency toward thin, small and high-capacity multi-layer ceramic
capacitor, there have been attempts to reduce the size of the
nickel particles used inside the multi-layer ceramic capacitor, and
there is also an attempt to prepare nanosized nickel particles.
[0006] Nickel nanoparticles may be prepared using various methods
such as liquid phase deposition, vapor phase deposition, plasma and
laser. Among the various methods, methods for preparing nickel
nanoparticles in a liquid phase have developed to reduce the
manufacturing cost.
[0007] Among the methods for preparing nickel nanoparticles in a
liquid phase, there is a method for preparing nickel particles by
adding sodium hydroxide to a mixture solution of nickel chloride
hydrate and hydrazine as a reducing agent (Choi. J.-Y. et al, J.
Am. Ceram. Soc. 2005, vol. 88, p. 3020). The method includes:
reacting hydrazine with nickel chloride to form a complex compound
and adding sodium hydroxide to the complex compound to form nickel
particles. In particular, it is possible to adjust the size of the
nickel particles to a size of 87 to 203 nm according to the ratio
of nickel chloride/hydrazine/sodium hydroxide. However, the nickel
particles prepared according to the method have problems in that it
is difficult to disperse the nickel particles since they are necked
to each other, and surfaces of the nickel particles are also not
smooth but rough.
[0008] Also among the methods for preparing nickel particles in a
liquid phase using hydrazine as the reducing agent, there is a
method for controlling the size of nickel particles by adding a
trace of cobalt (Kim, K.-M. et al, J. Electroceram. 2006, vol. 17,
p. 339.). In this method, nickel chloride or acetic acid nickel
hydrate was used as the nickel precursor. Here, the nickel
particles were prepared by mixing hydrazine with a nickel precursor
to form a mixture solution and adding sodium hydroxide to the
mixture solution. In this case, it is possible to control the size
of the nickel particles by adding a trace of cobalt chloride to the
mixture solution of nickel precursor and hydrazine. The nickel
particles prepared according to the method are in a range of 150 to
450 nm, and reduced in size with an increasing content of the added
cobalt. The addition of cobalt causes an increase in the number of
formed nucleus to control the size of the nickel particles, but
rough surfaces of the resulting nickel particles and their necking
behavior are still similar to those of the nickel particles
prepared by the previous methods.
[0009] As an alternative to control the size of nickel particles
under the control of nucleation in the art, there is a method for
preparing nickel particles by adding palladium or silver ions,
which facilitate the nucleation, to a solution including a nickel
precursor and a surfactant and incorporating reducing agents
hydrazine and ammonia (Chou, K.-S. et al, J. Nanoparticle Res.
2001, vol. 3, p. 127.). The size of the nickel particles prepared
according to this method is in a range of 10 to 25 nm, which is
significantly reduced, compared to the convention methods. However,
the synthesized nickel particles have problems in that some nickel
hydroxide, in addition to pure nickel, is present in the nickel
particles, and it is impossible to mass-produce the nickel
particles due to the very low reaction concentration.
[0010] In addition to the method for preparing nickel particles
using the nickel precursor and the reducing agent hydrazine, there
is also a known method for preparing nickel particles by thermally
cracking a nickel alkoxide precursor. In this method, the nickel
particles are prepared by synthesizing a nickel-aminoalkoxy metal
complex compound, dissolving the complex compound in an organic
solvent such as toluene and heating the resulting mixture to
thermally crack the complex compound. Here, synthesized nickel
particles is very small in size with diameters ranging from 3 to 5
nm, but the nickel particles having various shapes such as rod as
well as the spherical shape are present in a mixed form, and also
entangled with each other. This preparation method has problems in
that an additional process of preparing a metal complex compound is
required, it is difficult to mass-produce the metal complex
compound, and the nickel particles are too small in size to use the
metal complex compound as an internal electrode material of the
multi-layer ceramic capacitor.
[0011] Therefore, there is a continuous demand for developing
methods that may more easily control the sizes and shapes of the
nickel nanoparticles, as well as mass-producing the nickel
nanoparticles with lower expense.
SUMMARY OF THE INVENTION
[0012] The present invention is designed to solve the problems of
the prior art, and therefore it is an object of the present
invention to provide a method for preparing nickel nanoparticles
capable of easily controlling particle sizes and shapes of nickel
nanoparticles and obtaining a high yield of nickel nanoparticles
using a process that is simpler than methods used to mass-produce
the nickel nanoparticles.
[0013] According to an aspect of the present invention, there is
provided a method for preparing nickel nanoparticles including:
mixing a nickel precursor, organic amine and a reducing agent to
prepare a mixture; and heating the mixture. Here, an organic
solvent may be further mixed with the mixture.
[0014] In this case, the nickel precursor may be at least one
selected from the group consisting of nickel chloride (NiCl.sub.2),
nickel sulfate (NiSO.sub.4), nickel acetate
(Ni(OCOCH.sub.3).sub.2), nickel acetylacetonate
(Ni(C.sub.5H.sub.7O.sub.2).sub.2), halogenated nickel (NiX.sub.2,
wherein X is F, Br, or I), nickel carbonate (NiCO.sub.3), nickel
cyclohexanebutyrate
([C.sub.6H.sub.11(CH.sub.2).sub.3CO.sub.2].sub.2Ni), nickel nitrate
(Ni(NO.sub.3).sub.2), nickel oxalate (NiC.sub.2O.sub.4), nickel
stearate (Ni(H.sub.3C(CH.sub.2).sub.16CO.sub.2).sub.2), nickel
octanoate ([CH.sub.3(CH.sub.2).sub.6CO.sub.2].sub.2Ni) and hydrates
thereof.
[0015] Also, the organic amine may be presented by C.sub.nNH.sub.2
(wherein, n is an integer of 4.ltoreq.n.ltoreq.30). For example,
the organic amine may include at least one selected from the group
consisting of oleyl amine, dodecyl amine, lauryl amine, octyl
amine, trioctyl amine, dioctyl amine and hexadecyl amine.
[0016] In addition, the reducing agent may include, for example, at
least one selected from the group consisting of sodium borohydride
(NaBH.sub.4), tetrabutylammonium borohydride
((CH.sub.3CH.sub.2CH.sub.2CH.sub.2).sub.4N(BH.sub.4)), lithium
aluminumhydride (LiAlH.sub.4), sodium hydride (NaH),
borane-dimethylamine complex((CH.sub.3).sub.2NH.BH.sub.3) and
alkanediol (HO(CH.sub.2).sub.nOH, wherein n is an integer of
5.ltoreq.n.ltoreq.30).
[0017] Additionally, the organic solvent may include at least one
selected from the group consisting of an ether-based organic
solvent (C.sub.nOC.sub.n, wherein n is an integer of
4.ltoreq.n.ltoreq.30), a saturated hydrocarbon-based organic
solvent (C.sub.nH.sub.2n+2, wherein n is an integer of
7.ltoreq.n.ltoreq.30), an unsaturated hydrocarbon-based organic
solvent (C.sub.nH.sub.2n, wherein n is an integer of
7.ltoreq.n.ltoreq.30), and an organic acid-based organic solvent
(C.sub.nCOOH, wherein n is an integer of 5.ltoreq.n.ltoreq.30). For
example, the ether-based organic solvent may be at least one
selected from the group consisting of trioctylphosphine oxide,
alkyl phosphine, octyl ether, benzyl ether, and phenyl ether, and
the saturated hydrocarbon-based organic solvent may be at least one
selected from the group consisting of hexadecane, heptadecane and
octadecane. Also, the unsaturated hydrocarbon-based organic solvent
may be at least one selected from the group consisting of octene,
heptadecene and octadecene, and the organic acid-based organic
solvent may be at least one selected from the group consisting of
oleic acid, lauric acid, stearic acid, mysteric acid and
hexadecanoic acid.
[0018] In the operation of heating the mixture, the mixture may be
heated to a temperature of 50 to 450.degree. C., and the heating
time may be in a range from 1 minute to 8 hours.
[0019] Furthermore, the method for preparing nickel nanoparticles
according to one exemplary embodiment of the present invention may
further include: separating the nickel nanoparticles from the
heated mixture after the operation of heating the mixture. Here,
the operation of separating the nickel nanoparticles from the
heated mixture may include: adding ethanol or acetone to the heated
mixture to precipitate the nickel nanoparticles and separating the
precipitated nickel nanoparticles.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] The above and other aspects, features and other advantages
of the present invention will be more clearly understood from the
following detailed description taken in conjunction with the
accompanying drawings, in which:
[0021] FIG. 1 is a diagram illustrating a result obtained when the
nickel nanoparticles prepared in Example 1 are observed with a
transmission electron microscope.
[0022] FIG. 2 is a diagram illustrating a particle size
distribution of the nickel nanoparticles.
[0023] FIG. 3 is a diagram illustrating an electron diffraction
result of the nickel nanoparticles.
[0024] FIG. 4 is a diagram illustrating an analytic result of X-ray
diffraction pattern of the nickel nanoparticles.
[0025] FIG. 5 is a diagram illustrating a result obtained when the
nickel nanoparticles prepared in Example 2 are observed with a
transmission electron microscope.
[0026] FIG. 6 is a diagram illustrating a result obtained when the
nickel nanoparticles prepared in Example 3 are observed with a
transmission electron microscope.
[0027] FIG. 7 is a diagram illustrating a result obtained when the
nickel nanoparticles prepared in Example 4 are observed with a
transmission electron microscope.
[0028] FIG. 8 is a diagram illustrating a result obtained when the
nickel nanoparticles prepared in Example 5 are observed with a
transmission electron microscope.
[0029] FIG. 9 is a diagram illustrating a result obtained when the
nickel nanoparticles prepared in Example 6 are observed with a
transmission electron microscope.
[0030] FIG. 10 is a diagram illustrating a result obtained when the
nickel nanoparticles prepared in Example 7 are observed with a
transmission electron microscope.
[0031] FIG. 11 is a diagram illustrating a result obtained when the
nickel nanoparticles prepared in Example 8 are observed with a
transmission electron microscope.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0032] Hereinafter, exemplary embodiments of the present invention
will now be described in detail with reference to the accompanying
drawings. However, it is apparent to those skilled in the art that
modifications and variations may be made without departing from the
scope of the invention. Therefore, the exemplary embodiments of the
present invention will be provided for the purpose of better
understanding of the present invention as apparent to those skilled
in the art.
[0033] In the method for preparing nickel nanoparticles according
to one exemplary embodiment of the present invention, first of all,
the nickel nanoparticles are prepared by mixing a nickel precursor
and organic amine to prepare a nickel precursor mixture and heating
the nickel precursor mixture to thermally crack the nickel
precursor mixture.
[0034] The nickel precursor, which may be used in the present
invention, may be at least one selected from the group consisting
of, but is not particularly limited to, nickel chloride
(NiCl.sub.2), nickel sulfate (NiSO.sub.4), nickel acetate
(Ni(OCOCH.sub.3).sub.2), nickel acetylacetonate
(Ni(C.sub.5H.sub.7O.sub.2).sub.2), halogenated nickel (NiX.sub.2,
wherein, X is F, Br, or I), nickel carbonate (NiCO.sub.3), nickel
cyclohexanebutyrate
([C.sub.6H.sub.11(CH.sub.2).sub.3CO.sub.2].sub.2Ni), nickel nitrate
(Ni(NO.sub.3).sub.2), nickel oxalate (NiC.sub.2O.sub.4), nickel
stearate (Ni(H.sub.3C(CH.sub.2).sub.16CO.sub.2).sub.2), nickel
octanoate ([CH.sub.3(CH.sub.2).sub.6CO.sub.2].sub.2Ni) and hydrates
thereof. Here, any of compounds that may be used as a nickel source
may be used as the nickel precursor in the method for preparing
nickel nanoparticles according to one exemplary embodiment of the
present invention.
[0035] Unlike the conventional methods for preparing nickel
nanoparticles, organic amine is used in the method for preparing
nickel nanoparticles according to one exemplary embodiment of the
present invention. The organic amine may function as an organic
solvent, or a reducing agent. When an additional solvent is added
to the mixture of nickel nanoparticles, an organic solvent may be
used instead of an aqueous solvent due to the added organic
amine.
[0036] In accordance with one exemplary embodiment of the present
invention, since the organic amine is used to prepare the nickel
nanoparticles, the prepared nickel nanoparticles may be coated with
the organic amine. Therefore, the nickel nanoparticles have
excellent dispersing property with respect to other organic
solvents when the nickel nanoparticles will be used later.
Therefore, when the nickel nanoparticles are, for example,
dispersed in the organic solvent so as to apply the nickel
nanoparticles to an internal electrode of a multi-layer ceramic
capacitor, an additional process is not required due to the
dispersion of the nickel nanoparticles.
[0037] The organic amine may be represented by C.sub.nNH.sub.2
(wherein, n is an integer of 4.ltoreq.n.ltoreq.30). The organic
amine that may be used in the present invention, for example,
includes, but is not particularly limited to, oleyl amine, dodecyl
amine, lauryl amine, octyl amine, trioctyl amine, dioctyl amine and
hexadecyl amine.
[0038] In addition to the organic amine, the nickel precursor
mixture may further include an organic solvent when an additional
solvent is used in the nickel precursor mixture.
[0039] The organic solvent used herein includes at least one
selected from the group consisting of, but is not particularly
limited to, an ether-based organic solvent (C.sub.nOC.sub.n,
wherein n is an integer of 4.ltoreq.n.ltoreq.30), a saturated
hydrocarbon-based organic solvent (C.sub.nH.sub.2n+2, wherein n is
an integer of 7.ltoreq.n.ltoreq.30), an unsaturated
hydrocarbon-based organic solvent (C.sub.nH.sub.2n, wherein n is an
integer of 7.ltoreq.n.ltoreq.30) and an organic acid-based organic
solvent (C.sub.nCOOH, wherein n is an integer of
5.ltoreq.n.ltoreq.30).
[0040] The ether-based organic solvent that may be used in the
present invention, for example, includes, but is not particularly
limited to, trioctylphosphine oxide (TOPO), alkyl phosphine, octyl
ether, benzyl ether and phenyl ether.
[0041] The saturated hydrocarbon-based organic solvent that may be
used in the present invention, for example, includes, but is not
particularly limited to, hexadecane, heptadecane and octadecane.
Also, the unsaturated hydrocarbon-based organic solvent that may be
used in the present invention includes, but is not particularly
limited to, octene, heptadecene and octadecene.
[0042] The organic acid-based organic solvent that may be used in
the present invention includes, but is not particularly limited to,
oleic acid, lauric acid, stearic acid, mysteric acid and
hexadecanoic acid.
[0043] A reducing agent is mixed with the nickel precursor mixture.
The reducing agent that may be used in the present invention, for
example, includes, but is not particularly limited to, sodium
borohydride (NaBH.sub.4), tetrabutylammonium borohydride (TBAB,
(CH.sub.3CH.sub.2CH.sub.2CH.sub.2).sub.4N(BH.sub.4)), lithium
aluminumhydride (LiAlH.sub.4), sodium hydride (NaH),
borane-dimethylamine complex((CH.sub.3).sub.2NH.BH.sub.3) and
alkanediol (HO(CH.sub.2).sub.nOH, wherein n is an integer of
5.ltoreq.n.ltoreq.30).
[0044] The nickel precursor mixture is heated and thermally
cracked. A heating temperature of the nickel precursor mixture may
be in a range of 50 to 450.degree. C., preferably 60 to 400.degree.
C., and more preferably 80 to 350.degree. C. And the nickel
precursor mixture may be heated for 1 minute to 8 hours.
[0045] When the nickel precursor mixture is heated and thermally
cracked in the method for preparing nickel nanoparticles according
to one exemplary embodiment of the present invention, the nickel
nanoparticles are prepared. The prepared nickel nanoparticles may
be separated from the nickel precursor mixture, for example, by
adding ethanol or acetone to the heated nickel precursor mixture to
precipitate the nickel nanoparticles and centrifuging the
precipitated nickel nanoparticles.
[0046] In accordance with one exemplary embodiment of the present
invention, sizes of the prepared nickel nanoparticles may be
controlled more effectively according to the reaction conditions.
In the following Examples, nickel nanoparticles are prepared by
changing concentration of a nickel precursor, concentration and
kinds of reducing agents and/or reaction temperature to control the
sizes of the nickel nanoparticles.
EXAMPLES
[0047] Hereinafter, exemplary embodiments of the present invention
are described in more detail. In the following Examples 1 to 8,
nickel nanoparticles are prepared according to the method of the
present invention.
Example 1
[0048] Preparation of Nickel Nanoparticles
[0049] 13 g of nickel chloride as a nickel precursor, 200 ml of
oleyl amine as organic amine, and 0.5 g of tetrabutylammonium
borohydride (TBAB) as a reducing agent were put into a flask under
an argon atmosphere, mixed, and then heated to a temperature of
100.degree. C. The resulting mixture solution was kept at the
temperature for 1 hour. The mixture solution was heated to a
temperature of 160.degree. C., and kept for 1 hour. Then, the flask
is cooled to a room temperature, and 300 ml of ethanol was added to
the mixture solution to precipitate nanoparticles, and 6.1 g of the
precipitated nanoparticles were recovered using a centrifuge. In
this case, a reaction yield of the nanoparticles was 99% or
more.
[0050] 10 mg of the synthesized nickel nanoparticles were dispersed
in a solvent such as alcohol or toluene. 20 .mu.l of a nickel
nanoparticle-containing solution was dropped onto a TEM grid
(commercially available from Ted Pella Inc.) coated with carbon
film, dried for approximately 20 minutes, and then observed using a
transmission electron microscope (HRTEM, commercially available
from Philips, acceleration voltage: 200 kV). FIG. 1 is a diagram
illustrating a result obtained when the nickel nanoparticles
prepared in Example 1 are observed with a transmission electron
microscope. Referring to FIG. 1, it was revealed that the nickel
nanoparticles prepared in Example 1 have a uniform size and a round
particle shape. The size of the nickel nanoparticles observed with
the transmission electron microscope were measured, and a size
distribution of the nickel nanoparticles was shown in FIG. 2. Here,
an average particle size of the nickel nanoparticles was 50.8.+-.10
nm.
[0051] Also, a crystal structure of the nickel nanoparticles was
observed using an electron diffraction in the transmission electron
microscope. FIG. 3 is a diagram illustrating an electron
diffraction result of the nickel nanoparticles prepared in Example
1. From the electron diffraction result, it was confirmed that the
prepared nickel nanoparticles have a cubic crystal structure. In
addition, an X-ray diffractometer (commercially available from
Rikagu) was used to analyze the crystal structure of the nickel
nanoparticles. FIG. 4 is a diagram illustrating an analytic result
of X-ray diffraction pattern of the nickel nanoparticles prepared
in Example 1. From the analytic result of X-ray diffraction
pattern, it was also confirmed that the nickel nanoparticles have
the same cubic crystal structure as in the electron diffraction
result.
Example 2
[0052] Nickel nanoparticles were prepared in the same manner as in
Example 1, except that 6.5 g of nickel chloride was used to control
an amount of the nickel precursor. FIG. 5 is a diagram illustrating
a result obtained when the nickel nanoparticles prepared in Example
2 are observed with a transmission electron microscope. From the
results, it was revealed that the nickel nanoparticles have a size
of 38.3.+-.11 nm, which is smaller than the nickel nanoparticles
prepared in Example 1.
Example 3
[0053] Nickel nanoparticles were prepared in the same manner as in
Example 1, except that 26 g of nickel chloride was used to control
an amount of the nickel precursor. FIG. 6 is a diagram illustrating
a result obtained when the nickel nanoparticles prepared in Example
3 are observed with a transmission electron microscope. From the
results, it was revealed that the nickel nanoparticles have a size
of 94.+-.22 nm, which is larger than the nickel nanoparticles
prepared in Example 1.
Example 4
[0054] Nickel nanoparticles were prepared in the same manner as in
Example 1, except that the nickel nanoparticles were prepared at
180.degree. C. so as to control a reaction temperature. FIG. 7 is a
diagram illustrating a result obtained when the nickel
nanoparticles prepared in Example 4 are observed with a
transmission electron microscope. From the results, it was revealed
that the nickel nanoparticles are larger in size than the nickel
nanoparticles prepared in Example 1.
Example 5
[0055] Nickel nanoparticles were prepared in the same manner as in
Example 1, except that the nickel nanoparticles were prepared at
200.degree. C. so as to control a reaction temperature. FIG. 8 is a
diagram illustrating a result obtained when the nickel
nanoparticles prepared in Example 5 are observed with a
transmission electron microscope. From the results, it was revealed
that the nickel nanoparticles are larger in size than the nickel
nanoparticles prepared in Example 1.
Example 6
[0056] Nickel nanoparticles were prepared in the same manner as in
Example 1, except that TBAB was not used to control an amount of
the added reducing agent. FIG. 9 is a diagram illustrating a result
obtained when the nickel nanoparticles prepared in Example 6 are
observed with a transmission electron microscope. From the results,
it was revealed that the nickel nanoparticles are larger in size
than the nickel nanoparticles prepared in Example 1, and also that
the nickel nanoparticles with other shapes in addition to the round
shape are prepared.
Example 7
[0057] Nickel nanoparticles were prepared in the same manner as in
Example 1, except that 0.25 g of TBAB was used to control an amount
of the added reducing agent. FIG. 10 is a diagram illustrating a
result obtained when the nickel nanoparticles prepared in Example 7
are observed with a transmission electron microscope. From the
results, it was revealed that the nickel nanoparticles are larger
in size than the nickel nanoparticles prepared in Example 1.
Example 8
[0058] Nickel nanoparticles were prepared in the same manner as in
Example 1, except that 2.6 g of 1,2-hexadecanediol was used instead
of TBAB. FIG. 11 is a diagram illustrating a result obtained when
the nickel nanoparticles prepared in Example 8 are observed with a
transmission electron microscope. From the results, it was revealed
that the nickel nanoparticles are larger in size than the nickel
nanoparticles prepared in Example 1.
[0059] The particle sizes of the nickel nanoparticles prepared in
Examples 1 to 8 were varied according to the conditions such as the
reaction conditions and the presence of the reducing agent.
Therefore, it was revealed that the nickel nanoparticles may be
prepared in a simpler manner under the control of the sizes and
shapes of nanosized nickel particles according to one exemplary
embodiment of the present invention.
[0060] As described above, the method for preparing nickel
nanoparticles according to one exemplary embodiment of the present
invention may be useful to easily control the particle sizes and
shapes of the nickel nanoparticles and mass-produce a high yield of
the nickel nanoparticles that have a uniform size distribution with
a size of 100 nm or less when the nickel nanoparticles are prepared
using the method according to one exemplary embodiment of the
present invention.
[0061] In accordance with the exemplary embodiment of the present
invention, since the organic amine is used to prepare the nickel
nanoparticles, the prepared nickel nanoparticles are coated with
the organic amine. Therefore, the nickel nanoparticles have
excellent dispersing property with respect to other organic
solvents when the nickel nanoparticles will be used later.
Therefore, the method for preparing nickel nanoparticles according
to one exemplary embodiment of the present invention may be useful
to simplify the preparation processes since an additional process
is not required to disperse the nickel nanoparticles in other
solvents.
[0062] Furthermore, the method for preparing nickel nanoparticles
according to one exemplary embodiment of the present invention may
be useful to more effectively prepare the nickel nanoparticles
having a desired particle size since the sizes of the nickel
nanoparticles may be controlled according to the concentration of
the nickel precursor, the concentration and kinds of the reducing
agents and/or the reaction temperature.
[0063] While the present invention has been shown and described in
connection with the exemplary embodiments, it will be apparent to
those skilled in the art that modifications and variations can be
made without departing from the spirit and scope of the invention
as defined by the appended claims.
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