Structural Characterization of Nanostructured Nickel Coated Carbon Fibers by X-Ray Line Broadening

Abstract

Average grain size, microstrain and anisotropy factor of dislocation have been estimated from x-ray diffraction patterns of as-produced, annealed and oxidized nickel coated carbon fibers, using modified Williamson and Hall method. The results show a high anisotropy due to diffraction line broadening for both as-received and annealed specimen. Air oxidized fibers show nearly no anisotropy. The anisotropic strain broadening of diffraction profiles was accounted for by dislocation contrast factors. The screw or edge character of dislocations was determined by analysing the dislocation contrast factors. Heat treated specimen at 500°C are formed only by graphite and nickel, while after oxidation, only NiO with cubic (NaCl type) structure (a = 0.417nm), and average grain size about 30nm, is present with graphite. A novel finding that a transparent nickel oxide film can be obtained when a composite material consisting of nickel and carbon is heat-oxidized in air according to a simple treatment involving a heat oxidation temperature of 500°C and a heat oxidation time of 60 minutes. [DOI: 10.1380/ejssnt.2008.258]