Characterization of nano-structured W-, Ti-, V-, and Zr-doped carbon films

Abstract

Bonding structure of carbon and metal as well as nanostructural changes of metal-doped amorphous carbon films (a-C:Me) were investigated depending on metal type (W, Ti, V, Zr), concentration (<25 at%) and annealing temperature (<1300 K, except W: <2800 K).Pure C films exhibit ~2 nm distorted aromatic and graphene-like regions. Both increase in size with annealing. After deposition the metals have carbide-like bonding and are mainly distributed atomically disperse in an amorphous environment. Annealing leads to formation of carbide crystallites (TiC, VC, ZrC, WC, W 2 C, WC 1-x ) of several nm. The VC particles reach the largest size up to 1300 K. All metal dopings reduce the erosion rate against oxidation (expect V) and hydrogen impact.

Erosion of tungsten-doped amorphous carbon films exposed to deuterium plasmas

“…One possible explanation is that the remaining carbon originates from the initial tungsten-carbon chemical bonding in the a-C:W film. Although at low deposition temperature no tungsten carbide crystal is formed in asdeposited a-C:W films, carbide bonds were shown to be the dominant chemical bonding structure of tungsten in a-C:W films [13,[24][25]. It is quite probable that not all carbon in the W-rich layer can be removed by chemical erosion under the conditions of our experiment.…”