Synthesis of carbon-encapsulated iron carbide nanoparticles on a polyimide thin film

Abstract

A monolayer of 20 nm sized Fe3C nanoparticles encapsulated by graphite was fabricated by heat treating a polyimide/Fe/polyimide thin-film stack. Transmission electron microscopy and Raman spectroscopy confirmed the graphitization of the polyimide film in the vicinity of the Fe3C particles when annealed above 600 degrees C. Carbon-encapsulated Fe3C nanoparticles with a narrow size distribution were produced by introducing two-step annealing to initially produce a monolayer of gamma-Fe2O3 particles which was converted into carbon-encapsulated Fe3C nanoparticles during the second annealing stage. The thus-produced nanoparticles exhibited a saturation magnetization of 55.4 emu g(-1) and coercivity of 360 Oe at room temperature.