  We report a new approach to achieve growth of highly crystalline nickel
nanoparticles over an extended range of sizes (up to 100 nm in diameter) and
time scales (up to several hours) by diffusional transport of constituent
atoms. The experimental procedure presented offers control of the morphology of
the resulting particles and yields base metal nanocrystals suitable for
epitaxial deposition of noble metal shells and the preparation of materials
with improved catalytic properties. The reported precipitation system also
provides a good model for testing a diffusion-driven growth mechanism developed
specifically for the reduction process described.
