Transcript Hao Yin

Synthesis of carbon-encapsulated metal nanoparticles by a detonation
method
Pengwan Chen*, Hao Yin
State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology,
Beijing, 100081, China
*E-mail address: [email protected]
Introduction
• Carbon-based materials play a major role in today’s science
and technology.
• In the following years, carbon encapsulated metal
nanoparticles have become an active research area around the
world due to their possibility for catalysts, magnetic resonance
imaging, high density magnetic data storage, magnetic inks,
electrode in batteries, photo-catalytic activity.
• Moreover, the carbon coatings can endow these magnetic
particles with the biocompatibility and stability in many
organic and inorganic media.
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Introduction
• Over the past decades, many approaches have been developed to prepare
nanoparticles, mainly including modified arc discharge, CVD, ion-beam
co-sputtering, RF plasma technique, high-temperature heat treatment, the
laser vaporization technique, high pressure synthesis, combustion and
detonation.
• Detonation technology is an effective, convenient and cost-efficient
technology for producing diamond, carbon nanotube, graphene and carbon
encapsulated metal nanoparticles according to its unique characteristics:
quickness, self-heating and easy fabrication of carbon clusters.
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.The starting reactants were prepared in the form of a 20mm in diameter cylindrical grain made of the mixture of fine uniform powders and the cold pressed under pressure of 11
Experimental conditions
•RDX was used as explosive.
•Iron tristearate can provide both iron catalyst and carbon sources for
assembling carbon-encapsulated iron nanoparticles.
•Cobalt/Iron/ Nickel powders were used as catalytic and nano-metal
particles sources.
•Dicyandiamide(DCD) provides additional carbon source for shell
assembling.
•The starting reactants were made of the mixture of fine uniform
powders in the form a cylindrical grain.
•The detonation of explosive was initiated by a non-electric
detonator or heating .
•XRD, HRTEM, Raman, magnetic properties measured
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Apparatus
Protective medium
Explosive
detonator
Explosion vessel
Base
Explosion vessel
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Stainless steel pressure vessel
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Li Xiaojie. Composites science and technology 2009.
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Test No.
Starting mass mixture[wt%]
3
 ( g/cm )
P(GPa)
1
C3 H6 N6O6 (33.7) / C36 H70 FeO4 (66.7)
1.2
4.23
2
C3 H6 N6O6 (50) / C36 H70 FeO4 (50)
1.3
6.87
3
C3 H6 N6O6 (66.7) / C36 H70 FeO4 (33.3)
1.43
10
1.53
13.1
1.65
14.8
4
5
C3 H6 N6O6 (75) / C36 H70 FeO4 (25)
C3 H6 N6O6 (80) / C36 H70 FeO4 (20)
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Results and discussion
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Raman Investigation
NO
1:1
2:1
3:1
4:1
ID/IG
0.7
0.9
1.29
1.44
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HRTEM JEM-2010
Initiated by non-electric detonator
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Iron
carbide
0.34nm
Iron
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carbide
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3:1
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Mr/Ms<0.25 show
superparamagnetism behavior
Test no.
Ms(emu/g)
Mr(emu/g)
Hc (Gs)
Mr/Ms
1:1
10.16
1.46
200.64
0.144
2:1
19.105
1.22
92.838
0.064
3:1
19.11
0.28
110.38
0.015
4:1
25.57
0.54
59.02
0.021
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Initiated by heating
0.14nm
0.21nm
0.34nm
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3:1
0.21nm
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Test No.
Starting
mixture mass
ratio
C:H:N:O:metal
atomic ratio
 ( g/cm3)
P(GPa)
Proudct
a
RDX (10)  C2 N4 H4 (4)  Ni(1)
13.6:27.2:27.2:16:1
1.45
10.22
20-80nm
b
RDX (10)  C2 N4 H4 (5)  Fe(1)
14:28:28:15:1
1.47
9.71
No
19:38:38:16:1
1.43
7.82
10-100nm
c RDX (10)  C2 N4 H4 (8)  Co(1)
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0.35
RDX+DCD+Ni
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RDX+DCD+Co
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Conclusion
• The carbon-encapsulated metal nano-particles with a well
core–shell structure were produced by the detonation method.
• The results show that the diameters of nano-particles are 5100nm,
and
metal/metal
carbide
cores
and
graphitic/amorphous shells are formed in these nano-particles.
The thickness of the carbon shells are 2-10nm with 4-30
layers. The spacing of the carbon shell is about 0.34nm, which
is approximately equal to the spacing of graphite layers.
• It is found that carbon-encapsulated iron nano-particles can be
formed while RDX/ precursor mass ration is from 1:1 to 3:1
and exhibits certain superparamagnetic behavior.
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Thank you for your attention！
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