Assembly of tantalum porous films with graded oxidation profile from size-selected nanoparticles
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Functionally graded materials offer a way to improve the physical and chemical properties of thin films and coatings for different applications in the nanotechnology and biomedical fields. In this work, design and assembly of nanoporous tantalum films with a graded oxidation profile perpendicular to the substrate surface are reported. These nanoporous films are composed of size-selected, amorphous tantalum nanoparticles, deposited using a gas-aggregated magnetron sputtering system, and oxidized after coalescence, as samples evolve from mono- to multi-layered structures. Molecular dynamics computer simulations shed light on atomistic mechanisms of nanoparticle coalescence, which govern the films porosity. Aberration-corrected (S) TEM, GIXRD, AFM, SEM, and XPS were employed to study the morphology, phase and oxidation profiles of the tantalum nanoparticles, and the resultant films.
KeywordsTantalum Nanoparticles Coalescence Nanoporous film Graded oxidation XPS
We thank Adam Roberts (Kratos Analytical, UK) for the XPS experiments, and Dr. Chhagan Lal for helpful discussion on XPS results and Dr. Steven Aird for editing the manuscript.
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