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.
Bibliographical noteFunding Information:
The authors would like to acknowledge the Department of Science and Technology, Government of India , for financial support under the Grant no. SR/WOS-A/CS-69/2012 . The authors would also like to acknowledge the Centre for Nano Science and Engineering (CeNSE) and the Advanced Facility for Microscopy and Microanalysis (AFMM) of the Indian Institute of Science for the characterization work done.
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- A1. Growth models
- A1. Nanostructures
- A3. Metalorganic chemical vapor deposition
- B1. Nanomaterials
- B1. Oxides