Effect of annealing temperature and atmosphere on the structural, morphological and luminescent properties of TiO2 nanotubes

Titanium dioxide (TiO2) nanotubes prepared on titanium metal substrate are thermally annealed at various temperatures in nitrogen, air, oxygen and vacuum. In all annealing atmospheres, except in vacuum, the anatase phase becomes less prominent than the rutile phase for annealing temperatures above 6...

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Bibliographic Details
Published in:	Physica. B, Condensed matter Vol. 640; p. 414026
Main Authors:	Talla, A., Suliali, N.J., Goosen, W.E., Urgessa, Z.N., Motloung, S.V., Botha, J.R.
Format:	Journal Article
Language:	English
Published:	Elsevier B.V 01-09-2022
Subjects:	Luminescence Morphology Nanotubes Oxygen vacancies Self-trapped excitons Titanium dioxide Self-trapped excitons Oxygen vacancies Titanium dioxide Morphology Nanotubes Luminescence
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Summary:	Titanium dioxide (TiO2) nanotubes prepared on titanium metal substrate are thermally annealed at various temperatures in nitrogen, air, oxygen and vacuum. In all annealing atmospheres, except in vacuum, the anatase phase becomes less prominent than the rutile phase for annealing temperatures above 600 °C. The anatase phase is stable above 600 °C in vacuum but does not evolve significantly up to 900 °C. The morphologies of the nanotubes tend to deteriorate with increased annealing temperature, particularly in nitrogen, air and oxygen atmospheres. However, the integrity of the nanotubes is maintained up to 900 °C in vacuum. The photoluminescence emissions suggest mainly the presence of oxygen vacancies and self-trapped excitons, with respective emission bands around 2.5 eV and 2.3 eV. The results show that the annealing temperature and atmosphere strongly influence the crystalline and optical properties of the TiO2 nanotubes. •Anatase phase of anodic titanium dioxide nanotubes is stable up to 900 °C in vacuum.•The annealing temperature and atmosphere influence strongly the optical properties of the nanotube.•Passivation of non-radiative recombination centres of samples annealed in vacuum.•PL emissions suggest mainly the presence of oxygen vacancies and self-trapped excitons.
ISSN:	0921-4526 1873-2135
DOI:	10.1016/j.physb.2022.414026