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Anodised TiO 2 nano‐tubes: voltage ramp influence on the nano‐structured oxide and investigation of phase changes promoted by thermal treatments
Author(s) -
Regonini D.,
Bowen C. R.,
Stevens R.,
Allsopp D.,
Jaroenworaluck A.
Publication year - 2007
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.200675326
Subject(s) - nano , anodizing , materials science , oxide , phase (matter) , nanotechnology , thermal , composite material , chemistry , metallurgy , physics , thermodynamics , aluminium , organic chemistry
TiO 2 nano‐tubes have been generated by anodising commercially pure (99.6%) titanium in a 1 M solution of Na 2 SO 4 which contains a small amount of NaF (0.1–1 wt%). The use of an initial voltage ramp, prior to the application of a constant voltage to the cell, led to an increase in the thickness of the nano‐tube layer. The thermal stability of the nano‐tube layer has also been evaluated by annealing at a variety of temperatures, from 200 to 600 °C. Scanning Electron Microscopy (SEM) of the annealed nano‐tubes indicate that they are stable up to 500 °C. Raman spectroscopy was performed to monitor and evaluate the changes in the crystal structure promoted by the thermal treatments. The as‐prepared nano‐tubes are amorphous, while anatase begins to form at 300 °C and rutile is found at 550 °C, a temperature at which the nano‐tubes begin to collapse. Initial results obtained by characterising the as‐prepared nano‐tubes with Transmission Electron Microscopy (TEM) are also discussed. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)