Assembly of tantalum porous films with graded oxidation profile from size-selected nanoparticles

  • Vidyadhar SinghEmail author
  • Panagiotis Grammatikopoulos
  • Cathal Cassidy
  • Maria Benelmekki
  • Murtaza Bohra
  • Zafer Hawash
  • Kenneth W. Baughman
  • Mukhles SowwanEmail author
Research Paper


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.

Graphical Abstract

Design and assembly of tantalum nanoparticle porous films with a graded oxidation profile perpendicular to the substrate surface were fabricated by magnetron-sputter inert-gas aggregation system. At the top-most layers of the film, the larger free-surface areas of nanoparticles enable the formation of thermodynamically stable Ta2O5.


Tantalum 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.

Supplementary material

11051_2014_2373_MOESM1_ESM.doc (448 kb)
Supplementary material 1 (DOC 448 kb)


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Copyright information

© Springer Science+Business Media Dordrecht 2014

Authors and Affiliations

  • Vidyadhar Singh
    • 1
    Email author
  • Panagiotis Grammatikopoulos
    • 1
  • Cathal Cassidy
    • 1
  • Maria Benelmekki
    • 1
  • Murtaza Bohra
    • 1
  • Zafer Hawash
    • 1
  • Kenneth W. Baughman
    • 1
  • Mukhles Sowwan
    • 1
    • 2
    Email author
  1. 1.Nanoparticles by Design Unit Okinawa Institute of Science and Technology (OIST) Graduate University OkinawaJapan
  2. 2.Nanotechnology Research LaboratoryAl-Quds University East JerusalemPalestine

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