Orientation of carbon Nano-Fiber in carbon/silica composite prepared under high magnetic field

Carbon/silica composite films were prepared from colloidal silica aqueous solution in which vapour grown carbon nano-fibers dispersed. The orientation of nano-fibers was attempted by dip-coating substrates under high magnetic field up to 10 T. The fibers started to align along the direction of magnetic field below 1 T. The degree of orientation was saturated at about 6 T. The anisotropic susceptibility, Δχχ_//-χ_⊥, was estimated to be (3.051.10)×10^-7 cm³/mol from the fitting of numerical simulation. It was smaller than that reported in previous studies. It was deduced that perturbation of fiber orientation in the sol during drawing and drying, and the existence of coupled fibers in the starting materials suppressed the orientation of fibers.