Magnetic Properties of Fe-Co Catalysts for Carbon Nanofiber Synthesis
POSTER
Abstract
The magnetic properties of Fe-Co alloys used as catalysts for vertically-aligned carbon nanofiber (VACNF) growth are presented. 10 nm thick layers of Fe$_x$Co$_{100-x}$ of varying composition ($10 \le x \le 75$) are deposited on Si wafers by a co-sputtering technique. VACNFs are then grown by Plasma-Enhanced Chemical Vapor Deposition (PECVD) in an atmosphere of NH$_3$ and C$_2$H$_2$ at a temperature of $\sim 570^{\circ}$C. The catalyst particles on the tips of the VACNFs are 30--80 nm in size after growth. The magnetic properties are investigated at various stages of the fabrication process by SQUID magnetometry in a field range of $|H|\le 10$ kOe and temperatures of $T = 5$--300 K. The particles are ferromagnetic with moderate coercivity and remanence. The magnetization, however, is lower than expected at each stage.
*This work was supported by the Material Sciences and Engineering Division Program of the U.S. DOE Office of Science. A portion of this research was conducted at the CNMS.