Structure of metal nanowires in nanoporous alumina membranes studied by EXAFS and X-ray diffraction

The structure of nanowires of different metals grown within nanoporous alum ina membranes has been studied by EXAFS, WAXS and high energy X-ray diffrac tion. Nanowires of gold, silver, copper and iron adopt the lattice structur e and bond distances of the bull, metals, Cobalt nanowires on the other han d were composed of a mixture of hcp phase, stable at room temperature, and fcc phase., which in bulk cobalt is normally stable only at high temperatur es, in a ratio depending on the pore size. The nanowires are non-continuous but are made of nanocrystallites whose shape and size was found to depend strongly on the metal. All the metals except gold showed the presence of a preferred orientation which was slight in the case of Ag and Cu but much st ronger in the case of iron and cobalt nanowires.