potential applications of carbon nanotubes
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POTENTIAL APPLICATIONS OF CARBON NANOTUBESBernd Büchner, Institut für Festkörperforschung, IFW DresdenInstitut für Festkörperphysik, TU Dresden
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Bernd BüchnerInstitut für Festkörperforschung, IFW Dresden
Institut für Festkörperphysik, TU Dresden
Potential Applications of Carbon Nanotubes
Magnetism of Carbon Nanotube Based Systems
,,Ferromagnetic Grass‘‘ Biomedical applicationsNovel magnetic
SPM Probes
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Carbon Nanotubes
Graphite
MWNT (multi walled nanotube)
1 graphenelayer
2 +n graphenelayers
SWNT (single wallednanotube)
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Multi-walled Carbon Nanotubes
Multi walled tubes
5nm
Fe
Partially filled MWCNT:
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filled MWNT
Pyrolysis of metallocenes
[ Fe (C5H5)2 , Co (C5H5)2 or Ni (C5H5)2 ]
Fe-, Co- and Ni-filled MWNTAlloy-filled MWNT
10 nm
FeNi
10 nm
40 nm
Co
1 µm
40 60 80 100 120 (degrees)2Θ
Fe3C
(102
)
Fe3C
(112
)
C(0
04)
C(1
10)
γ Fe
(222
)
γ Fe
(311
)α F
e (2
00)
γ Fe
(220
)
γ Fe
(200
)
γ Fe
(111
)
S i
S iC(0
02)
α F
e (2
20)
α F
e (2
11)
α F
e (1
10)
S i
In
tens
ity (a
rb.u
.)
X-ray diffraction: bcc (α-Fe), fcc (γ-Fe) and Fe3C, texture for α-Fe (110) and γ-Fe (111)
Synthesis and characterization of filled carbon nanotubes
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Synthesis and characterization of filled carbon nanotubes
9 µm
Ni
Co-filled CNTs Ni-filled CNTs Fe-Co alloy-filled CNTs
25 µm
Fe-filled CNTs
Ref.: A. Leonhardt et. al, Diamond and Related Materials 12 (2003) 790.T. Mühl et. al, J. Appl. Phys. 93 (10) (2003) 7894. R. Kozhuharova et. al, Journal of Materials Science: Materials in Electronics 14 (2003) 789.C. M. Schneider et. al, Diamond and Related Materials 13 (2004) 215.R. Kozhuharova et. al, submitted to Applied Surface Science.
20 µm
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Magnetic storage
Magnetism of Fe-filled nanotubes
-250 0 250
µ0H / mT
-0.5
0
0.5
m /
msa
tH parallel substrateH perpendicular substrate
Fe22
-1000 0 1000µ0H / mT
-1
0
1m
/ m
sat
uniaxial anisotropy
coercivity of 56 mT at RT (bulk Fe: 0.09 mT)
filled nanotubes(Fe, Co, Ni)
20 µm
Outlook• self-organized growth• well defined diameter (length) • other materials (FePt)• ....
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C- shell -> long-time chemically stable Fe nanowires
-1000 -500 0 500 1000-0,15
-0,10
-0,05
0,00
0,05
0,10
0,15
Ms*m
m-2
/mem
u*m
m-2
µ0H / mT
perpenticularparallel
H28d - orginal14d, 22 °C, wet atmosphere5h, 50 °C, O2-atmosphere
2 months in wet atmosphere, RT
5h in O2– atmos-
phere, 50°C (!)
Fe-filled CNT(d = 30nm)
Fe filled MWCNT: Chemically stable Fe nanomagnets
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Fe filled MWCNT: Bio-compatible nanomagnets
Ferromagnetic nanocontainer for diagnostic and therapy of cancer
10 nmantibodies
cellantigene
functional groupsferromagnetica
drugs
temperature sensor
Idea: ,,Transfer‘‘ of (functionalized) ferromagnetic nanotubes in cells Manipulation by external magnetic fields (e.g. alignement, heating) Detection of magnetic particals by magnetic probes (SQUID, NMR, etc.)
Cooperation: - Department of Urology, TU Dresden- Systenanix GmbH, Dresden
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Biomedical applications of ferromagnetic filled carbon nanotubes
Insertion of nanotubes in cells and tissue
Slice of muscle tissue containingFe-CNTs
TEM-picture of cellscontaining Fe-CNTs
Macroscopic depot (mm area) of Fe-CNTs
Fe-CNTs
Animal experiments: fm-MWCNT nontoxicinvestigation period 4 months
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-1000 -500 0 500 1000
µ0H (mT)
-300
-200
-100
0
100
200
300
m
(µem
u)-250 0 250
µ0H (mT)
-200
-100
0
100
200
m
(µem
u)
Magnetisation measurements on cellular suspensions doped with Fe-filled nanotubes
-500 0 500
µ0H (mT)
-600
-400
-200
0
200
400
600
m
(µem
u)
cellular suspension on glass substrate 3∗3mm ⇒air dried ⇒ ≅ 1 mg
cellular suspension ≅ 5µl on fleece paper ⇒ air dried
small anisotropy ⇒
nanotubes tend to be parallel to the glass substrate
no detectable anisotropy in the fleece paper
Magnetisation typical for an ensemble ofnanotubes (saturation field, hystereses)
H parallel to thesubstrateH perpendicular to the substrate
HC=45mT HC=52mT
HC=25mT HC=24mT
Magnetisation curves of “cancer cells“
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Biomedical applications of ferromagnetic filled carbon nanotubes
Heating by AC magnetic fields
0
10
20
30
40
50
60
0 2 4 5,5 6 7,5 8 9,5 10 11,5 12 13,5 14,5 15,5
time [min]
tem
pera
ture
[°C
]
without Fe-CNTs
with Fe-CNTs
Fe-CNT/NaCl-suspension 1
Heating of Fe-CNTs inside tissue in a AC magnetic field
f = 231 kHz; H = 25 kA/m
Muscle tissue : before and after AC-heating
40
10
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Magnetometry on individualnanotubes using nano-sized Hall devices.(in cooperation with D. Grundler, HamburgS. Wirth, MPI-CPFS)
Fe-filled Carbonnanotube.
Silicon SPM tip
Magnetism of individual Nanotubes
New MFM probe:
Fe-filled nanotube attached at a conventional SPM probe.
Fe-filled Carbonnanotube.
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Ferromagnetic coating
Magnetic force microscopy
Cantilever spring constant ccant
Frequency drive = Frequency tip
Amplitude tip = f(frequency, mtip, ceff)
Phase tip = f(frequency, mtip, ceff)
ceff = ccant+ csample-tip
csample-tip ~ dFsample-tip / dz
csample-tip ~ Fsample-tip
tip
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Magnetism of individual Nanotubes
MFM on Fe-filled nanotubes:
SEM contrast
BSE contrast
MFM contrast
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Bending of Fe-filled nanotubes by AFM-based nanomanipulation
MFM contrastSEM
Before…
After manipulation
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-Remanent magnetization (Mr) of an individual Fe nanowire
-Length: 420 nm, diameter: 17 nm
-External magnetic field along the MWCNT axis applied prior tothe MFM measurement.
-Two remanent stray field configurations of opposite sign
Mr is normalised to +1/-1.
MFM of Fe-filled Carbon Nanotubes
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New MFM probeFe-filled nanotube attached at a conventional SPM probe
Silicon SPM tip
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Successful use as high resolution MFM probe
Outlook: Evaluation of these new MFM probes, e.g. by determination of the effective moments (dipole/monopole)
Fe filling
Silicon SPM tip
New MFM probeFe-filled nanotube attached at a conventional SPM probe
Topography (3 x 1) µm2
MFM contrast (phase)
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Outlook – Mechanical stability of the CNT MFM probes?
Vibration??
FIB milled hole
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Spin Transport in Carbon NanotubesFM1
FM2
Ferromagnetic contactsSpin injection in CNT
Field dependent transport (MR)Detection of spin direction
Spin transport in CNT
Outlook – Novel spinelectronic devices with f-MWCNT
No influence of the Fe-filling. Idea: Local removal of carbon shells
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Magnetism of Carbon Nanotube Based Systems
,,Ferromagnetic Grass‘‘ Spin transport in carbon nanotubes
-0.5 -0.4 -0.3 -0.2 -0.1 0 0.1
B,T
0
2
4
6
8
10
12
14
16
18
[R(B
)-R(0
.1T)
]/R(0
.1T)
, %
I = 5 nA
R(0.1T) = 2.4 MΩ
Biomedical applications Novel magnetic SPM Probes
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A. Leonhardt, I. Mönch, M. Ritschel, S. Hampel, R. Koshuva,
T. Mühl, A. Winkler, D. Elefant, S. Menzel,
H. Vinzelberg, C.M. Schneider, T. Gemming
IFW Dresden
A. Meye, K. Krämer, A. Wirth
Urologie, Technische Universität Dresden
G. Hammermann
Systenanics GmbH
DFG and BMBF for financial support