Short range order in Pd and PdO nanoparticles embedded in carbonaceous matrix studied with the XAFS spectroscopy

The short range order around Pd atoms in nanometer-size grains embedded in carbonaceous films deposited with two-step process: physical vapor deposition (PVD) followed by chemical vapour deposition (CVD) was studied. The Pd K-edge X-ray Absorption Fine Structure Spectroscopy was applied. We have found that grains obtained in a sole PVD process contained metallic fcc palladium or amorphous palladium oxide dependently on Pd concentration and duration time of process. In the oxide fraction a short range order around Pd atoms was strongly reduced as compared to a reference PdO powder. Subsequent CVD resulted in pure Pd fcc crystallites. The accompanying annealing was found to predominantly determine the content and structure of formed Pd grains.