AVS 58th Annual International Symposium and Exhibition
    Applied Surface Science Division Tuesday Sessions
       Session AS-TuP

Paper AS-TuP19
TiO2 Nanotube Growth Mechanism Studied with Scanning Auger Spectroscopy

Tuesday, November 1, 2011, 6:00 pm, Room East Exhibit Hall

Session: Applied Surface Science Poster Session
Presenter: Dennis Paul, Physical Electronics
Authors: D.F. Paul, Physical Electronics
S. Berger, University of Erlangen-Nürnberg, Germany
F. Schmidt-Stein, University of Erlangen-Nürnberg, Germany
S.P. Albu, University of Erlangen-Nürnberg, Germany
H. Hildebrand, University of Erlangen-Nürnberg, Germany
P. Schmuki, University of Erlangen-Nürnberg, Germany
J.S. Hammond, Physical Electronics
Correspondent: Click to Email
Anodic TiO2 nanotubes offer unique properties for a wide range of applications including energy conversion, photocatalysis and biomedical devices1, 2, 3. It is widely accepted that the initial growth of the nanotubes is based on the formation of a compact anodic oxide followed by the formation of etching grooves and pores in the oxide4, 5. The mechanism of steady state growth of the nanotubes from the embryonic pores has, however, remained a topic of debate. To evaluate a flow model1, 6 for the formation of the tubular structures, high spatial resolution Scanning Auger Spectroscopy data is used to elucidate the compositional variations across TiO2 nanotube layers grown in a fluoride containing ethylene glycol electrolyte. The layers were fractured parallel to the axes of the nanotubes and quantitative spectra, line scans and elemental maps were acquired along the walls of the nanotubes. The Auger data indicates the presence of a fluoride rich layer located between the tube walls, and in particular, the triple points of the hexagonally ordered nanotube arrays. This data supports fluoride dissolution as the reason for a transition from a porous oxide layer to tubular structures. This data also supports a flow model as a mechanism for the formation of the tubular morphology.