TY - JOUR
T1 - Crystallization of amorphous carbon in carbon-cobalt layered thin films
AU - Konno, T. J.
AU - Sinclair, R.
N1 - Funding Information:
Acknowledgements -We would like to thank J. T. Sizemore and S. Kapoor for their help during Raman spectroscopy. We are grateful to SigneticsC orp. for donation of sputtering equipment and to Kobe Steel U.S.A. for funding its refurbishment. This work was supported by the National Science Foundation (Grant No. DMR 8902232).
PY - 1995/2
Y1 - 1995/2
N2 - We investigated the crystallization behavior of amorphous carbon (a-C) in a-C/Co/a-C trilayer (C: 650 Å: Co: 70-210 Å thick) thin films using in situ transmission electron microscopy (TEM), differential scanning calorimetry (DSC) and Raman spectroscopy. In situ and ex situ TEM showed that a-C, in contact with cobalt, transforms into polycrystalline graphite upon heating above 500°C. The heat of crystallization, as measured by DSC, is 19 ± 2 kJ/mol-C. The Raman spectroscopy also confirmed Stokes scattering peaks at 1580 and 1360 cm-1, indicating the polycrystalline nature of the graphite. We did not observe any metastable cobalt-carbide phase formation during the reaction (as occurs in co-sputtered Co-C film crystallization), but our cross-section TEM revealed the presence of the face centered cubic (f.c.c.) Co phase between the a-C and graphite. This observation suggests that the crystallization or graphitization of the a-C is mediated by the Co phase, similar to the behavior in other eutectic metal-metalloid systems (e.g. Al-Si, Ag-Ge).
AB - We investigated the crystallization behavior of amorphous carbon (a-C) in a-C/Co/a-C trilayer (C: 650 Å: Co: 70-210 Å thick) thin films using in situ transmission electron microscopy (TEM), differential scanning calorimetry (DSC) and Raman spectroscopy. In situ and ex situ TEM showed that a-C, in contact with cobalt, transforms into polycrystalline graphite upon heating above 500°C. The heat of crystallization, as measured by DSC, is 19 ± 2 kJ/mol-C. The Raman spectroscopy also confirmed Stokes scattering peaks at 1580 and 1360 cm-1, indicating the polycrystalline nature of the graphite. We did not observe any metastable cobalt-carbide phase formation during the reaction (as occurs in co-sputtered Co-C film crystallization), but our cross-section TEM revealed the presence of the face centered cubic (f.c.c.) Co phase between the a-C and graphite. This observation suggests that the crystallization or graphitization of the a-C is mediated by the Co phase, similar to the behavior in other eutectic metal-metalloid systems (e.g. Al-Si, Ag-Ge).
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U2 - 10.1016/0956-7151(94)00289-T
DO - 10.1016/0956-7151(94)00289-T
M3 - Article
AN - SCOPUS:0029254277
SN - 0956-7151
VL - 43
SP - 471
EP - 484
JO - Acta Metallurgica et Materialia
JF - Acta Metallurgica et Materialia
IS - 2
ER -