Abstract
This work reports the structural, morphological and vibrational
properties of titanate nanotubes and nanoribbons obtained from
bidimensional structures by hydrothermal treatment of TiO2 in aqueous
NaOH solutions. The physical properties of these as-synthesized and
heat-treated nanostructures are discussed in comparison with their bulk
(Na2Ti3O7 and Na2Ti6O13) counterparts. The results obtained from several
characterization techniques allowed to conclude that the layers of both
as-synthesized nanotubes and nanoribbons are isostructural to the
Na2Ti3O7 compound. However, in the nanotubes, the chemical bonds are
deformed because of the curvature of walls while in the nanoribbons the
layers present structural disorder due only the size effects. The
thermal behavior of titanate nanoribbons is similar to those observed
for titanate nanotubes. When thermally treated titanate nanoribbons
change to bulk with a phase mixing of Na2Ti3O7 and Na2Ti6O13. We
conclude in this work that the chemical composition of both the titanate
nanotubes and the nanoribbons is the same, Na2-xHxTi3O7 center dot nH(2)O (0 <= x <= 2) and Raman spectroscopy can be used for an easy and
quick identification of both morphology and structure changes of the
nanosized titanates.
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