GraphITA,graphita.bo.imm.cnr.it/graphita2011/GraphITA_PDF_Talks/... · 2011-05-27 · Dr A.Dinescu,...
Transcript of GraphITA,graphita.bo.imm.cnr.it/graphita2011/GraphITA_PDF_Talks/... · 2011-05-27 · Dr A.Dinescu,...
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Effect of the synthesis parameters on the dc resistance of
graphite nanoplatelets thick films G. De Bellis*, F. Ruggeri, A. Broggi, A.Tamburrano, M.L. Santarelli, and M.S. Sarto
GraphITA, Laboratori Nazionali del Gran Sasso, Assergi (AQ)
May 15, 2011
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Outline
Synthesis of GNPs via Thermal Exfoliation
Fabrication of GNPs thick films
SEM and AFM characterizations
FTIR spectroscopy of GNP-based foils
DC conducivity measurements
Conclusions
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Graphite intercalation compounds (GIC)
1841 GICs first synthesized (with Potassium as the intercalant) [1]
1859 Brodie prepared the first graphitic acid (graphite oxide)
1898 Staudenmeier improved the Brodie process using sulfuric acid
1957 Hummers and Offemann further enhanced the technique
efficiency, considerably reducing the time required for the whole
process
[1] Schafhautl, 1841
Graphite intercalation compounds are formed by the insertion of atomic or molecular layers of a different chemical species called the intercalant between layers n a graphite host material
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GIC structure GraphITA 2011
Ic
Intercalant species
Graphene layer
The stage index n can be extracted from the relation Ic=(n-1)c0+ds
c0 ds
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Thermo-chemical Exfoliation
+ thermal shock
GIC flake +
Ultrasonication
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TEMPERATURE EXPANSION TIME
250°C 15s 30s 60s
500°C 5s 15s 30s 60s
750°C 5s 15s 30s 60s
1050°C 5s 15s 30s 50s
1150°C 5s 15s 30s 60s
1250°C 5s 15s 30s
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Expansion conditions
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SEM imaging GraphITA 2011
SEM Images courtesy of Dr A.Dinescu, IMT Bucharest
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AFM imaging 750°C-30s GraphITA 2011
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AFM imaging 1250°C-30s GraphITA 2011
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C-H stretching C=O stretching
C-O epoxy and alkoxy stretching
FTIR spectroscopy on GICs before and after thermal expansion
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GNP films preparation GraphITA 2011
Worm-like graphite Ultrasonication
Vacuum filtration
GNP film
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FTIR spectroscopy GraphITA 2011
Wavenumber (cm-‐1)
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Effect of the expansion temperature
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Wavenumber (cm-‐1)
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Effect of the expansion time
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Wavenumber (cm-‐1)
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High temperature expansion
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Wavenumber (cm-‐1)
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DC measurements experimental setup
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Source meter
Nano Voltmeter Four probe station
"↓$ = &/()(#) */+ [Ω/)*+,-.] ,= 0/"↓$ - [.//]
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DC measurements results
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Expansion conditions
Resistance (V/I) [Ω]
Conductivity* [S/m]
T 750° t 15s 0.194 5808
T 750° t 30s 0.191 5919
T 1050° t 15s 0.138 8063
T 1050° t 30s 0.120 9273
T 1150° t 5s 0.125 9627
T 1150° t 30s 0.121 9196
T 1250° t 5s 0.090 12393
*Extimated assuming an average film thickness of 200 µm
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Resistance vs expansion temperature
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Effect of the synthesis conditions on the EM performance of GNP-based nanocomposites
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Electrical conductivity of nanocomposites loaded with 0.5% wt GNPs
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Concluding remarks
The morphological and physical properties of GNPs produced
by TCE of GICs are strongly affected by expansion
temperature (T) and time (t)
FTIR spectra are nearly independent from those parameters
for T>1000°C
Proper choice of the processing conditions enables tailoring
of the electrical properties
GNP-filled composites with tailored EM properties can be
realized by properly choosing the process parameters for the
GNP synthesis
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Thanks for your attention
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