In situObservation of Carbon-Nanopillar Tubulization Caused by Liquidlike Iron Particles

Abstract

The tubulization process of amorphous carbon nanopillars was observed in situ by transmission electron microscopy. Amorphous carbon nanopillars were transformed into graphitic tubules by annealing at 650–900 °C in the presence of iron nanoparticles. A molten catalyst nanoparticle penetrated an amorphous carbon nanopillar, dissolving it, and leaving a graphite track behind. An iron nanoparticle moved with its shape changing like an earthworm. We concluded that the tubulization mechanism is a solid-(quasiliquid)-solid mechanism where the carbon phase transformation is a kind of liquid phase graphitization of amorphous carbon catalyzed by liquefied metal-carbon alloy nanoparticles