Biomedical Engineering Reference
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preparation of this kind of nanostructured titania by electrochemical
techniques has attracted the interest of researchers [25-31]. An early
report [32] demonstrated that the anodization of Ti foils in fluoride-
containing medium leads to porous nanostructured titania. Since
Macklin and Neat [33] reported the high capacity and reversibility of
lithium insertion into titanium oxide electrodes in lithium batteries,
a considerable research effort has been aimed at optimizing and
understanding the titanium oxide anode [23].
The electrochemical performances of self-organized TiO
2
nanotube obtained from Ti foils (references [26, 28] provide
examples of the fabrication process) and Ti thin films deposited
onto Si substrates have been examined according to a procedure
described in reference [34]. Layers of nanotubular titania (ntTiO
2
)
are directly produced by the anodization of Ti in fluoride-
containing medium and without the use of any template. We have
demonstrated that this kind of nanotubular morphology can be
beneficial for an extra lithium accommodation into the structure
apart from the interstitial and octahedral sites and allows the
manufacture of electrodes without the use of additives and binders
[35] in agreement with the study by Liu et al. [36]. The use of TiO
2
reduces the overall cell voltage, but it is reported to provide cells
with enhanced safety, low self-discharge, good capacity retention
on cycling, and high power due to the possibility to be used in the
nanoscale form. In addition, TiO
2
is chemically stable, economically
competitive, nontoxic, and an environmental “White Knight.”
5.3 FABRICATION OF SELF-ASSEMBLED TIO
2
NANOTUBES
5.3.1 Anodizaion of Titanium: Experimental Aspects
The fabrication of self-organized titania nanotube layers (ntTiO
2
)
onto two different substrates is one part of the aim of this chapter
and is presented here. In a typical experiment, Ti thin films with
a thickness of about 2
m were deposited by cathodic sputtering
using a D.C. triode system onto Si substrates engraved from p-type
Si(1 0 0) wafers with a resistivity of 1-10
μ
cm (WaferWorld, Inc.),
following a similar procedure given in reference [34]. The second Ti
Ω
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