Formation of carbon nano and micro structures on C1+ irradiated copper surfaces

Abstract

A series of experiments has identified mechanisms of carbon nano- and micro-structure formation at room temperature, without catalyst and in the environment of immiscible metallic surroundings. The structures include threaded nano fibres, graphitic sheets and carbon onions. Copper as substrate was used due to its immiscibility with carbon. Energetic carbon ions of 0.2-2.0 MeV irradiated Cu targets. Cu substrates, apertures and 3 mm diameter Transmission Electron Microscope copper grids were implanted with the carbon. We observed wide range of micrometer-size structures formed on Cu grids and along the edges of the irradiated apertures. These are shown to be threaded nano fibers (TNF) of few micrometer thicknesses with lengths varying from 10 to 3000 micrometer. Secondary electron microscopy (SEM) identifies the micrometer-size structures while Confocal microscopy was used to learn about the mechanisms by which C1+ irradiated Cu provides the growth environment. Huge carbon onions of diameters ranging from hundreds of nm to {\mu}m were observed in the as-grown and annealed samples. Transformations of the nanostructures were observed under prolonged electron irradiations of SEM and TEM. One of the immediate outcomes of our present study is relevant for the efforts to fabricate carbon onions with specific properties.