1. The role of γ-iron nanoparticulates in the growth of carbon nanotubes.
- Author
-
Khasanov, Airat, He, Jian, Gaillard, Jay, Yang, Keqin, Rao, Apparao M., Cameron, C. Michelle, Schmeltzer, J. M., Stevens, John G., and Nath, Amar
- Subjects
NANOPARTICLES ,CARBON nanotubes ,FERROMAGNETISM ,MOSSBAUER spectroscopy ,IRON ,MAGNETIC properties of metals ,NANOTUBES ,CATALYSTS - Abstract
Carbon nanotubes (∼200 nm diameter) are grown by chemical vapor deposition using catalytic iron particles. Mössbauer spectroscopy enables differentiation among relatively large Fe
3 C, α-Fe, and nanosized superparamagnetic fcc γ-Fe particles. The antiferromagnetic configuration of γ-Fe nanoparticles yields a significant fraction of uncompensated spins, producing a weak ferromagnetism that allows estimation of size (2–3 nm) via magnetization in zero field versus variable field cooling. This property of γ-Fe nanoparticles has not been previously employed. We propose that the surfaces of 200 nm iron carbide particles are covered with nanosized γ-Fe and graphitized carbon that participate in the catalytic growth of nanotubes. [ABSTRACT FROM AUTHOR]- Published
- 2008
- Full Text
- View/download PDF