TY - JOUR
T1 - Reconciling results of MOCVD of a CNT composite with equilibrium thermodynamics
AU - Dhar, Sukanya
AU - Arod, Pallavi
AU - Shivashankar, S. A.
PY - 2016/5/15
Y1 - 2016/5/15
N2 - Composition and microstructure of the composite films can be tailored by controlling the CVD process parameters if an appropriate model can be suggested for quantitative prediction of growth. This is possible by applying equilibrium thermodynamics. A modification of such standard modeling procedure was required to account for the deposition of a hybrid film comprised of carbon nanotubes (CNTs), metallic iron (Fe0), and magnetite (Fe3O4), a composite useful for energy storage. In contrast with such composite nature of the deposits obtained by inert-ambient CVD using Fe(acac)3 as precursor, equilibrium thermodynamic modeling with standard procedure predicts the deposition of only Fe3C and carbon, without any co-deposition of Fe and Fe3O4. A modification of the procedure comprising chemical reasoning is therefore proposed herein, which predicts simultaneous deposition of FeO1-x, Fe3C, Fe3O4 and C. At high temperatures and in a carbon-rich atmosphere, these convert to Fe3O4, Fe and C, in agreement with experimental CVD. Close quantitative agreement between the modified thermodynamic modeling and experiment validates the reliability of the modified procedure. Understanding of the chemical process through thermodynamic modeling provides potential for control of CVD process parameters to achieve desired hybrid growth.
AB - Composition and microstructure of the composite films can be tailored by controlling the CVD process parameters if an appropriate model can be suggested for quantitative prediction of growth. This is possible by applying equilibrium thermodynamics. A modification of such standard modeling procedure was required to account for the deposition of a hybrid film comprised of carbon nanotubes (CNTs), metallic iron (Fe0), and magnetite (Fe3O4), a composite useful for energy storage. In contrast with such composite nature of the deposits obtained by inert-ambient CVD using Fe(acac)3 as precursor, equilibrium thermodynamic modeling with standard procedure predicts the deposition of only Fe3C and carbon, without any co-deposition of Fe and Fe3O4. A modification of the procedure comprising chemical reasoning is therefore proposed herein, which predicts simultaneous deposition of FeO1-x, Fe3C, Fe3O4 and C. At high temperatures and in a carbon-rich atmosphere, these convert to Fe3O4, Fe and C, in agreement with experimental CVD. Close quantitative agreement between the modified thermodynamic modeling and experiment validates the reliability of the modified procedure. Understanding of the chemical process through thermodynamic modeling provides potential for control of CVD process parameters to achieve desired hybrid growth.
KW - A1. Growth models
KW - A1. Nanostructures
KW - A3. Metalorganic chemical vapor deposition
KW - B1. Nanomaterials
KW - B1. Oxides
UR - http://www.scopus.com/inward/record.url?scp=84960841961&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84960841961&partnerID=8YFLogxK
U2 - 10.1016/j.jcrysgro.2016.02.019
DO - 10.1016/j.jcrysgro.2016.02.019
M3 - Article
AN - SCOPUS:84960841961
VL - 442
SP - 41
EP - 46
JO - Journal of Crystal Growth
JF - Journal of Crystal Growth
SN - 0022-0248
ER -