Raman spectroscopic study of the influence of voltage-time on titania growth-fast anodized nanostructures

• M. Luna Cervantes ^[1] ; J. Hernández Torres ^[1] ; L. Zamora Peredo ^[1]
  1. [1] Universidad Veracruzana

     Universidad Veracruzana

     México

     
• Localización: Revista Mexicana de Física, ISSN-e 0035-001X, Vol. 65, Nº. 5, 2019, págs. 449-458
• Idioma: inglés
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• Resumen

  • TiO_(2) nanotubes were prepared by the anodization process of a set of titanium foils in order to study the influence of time and voltage on the morphology of them under a 1.2 wt % NH_(4)F salt concentration, taking advantage of this percent and remarking the great importance of the oxide growth-dissolution speed with this electrolyte concentration. The anodization process consists of an organic media of ethylene glycol, a voltage from 5 to 30 V for a time period from 1 to 6 hours, a constant potential of 30 V for a time lapse from 10 to 360 minutes and 5 to 480 seconds. All anodized samples are rinsed and annealed to 400◦C for 3 hours to obtain an anatase crystalline structure. The morphological characterization was carried out by Field Emission Scanning Electron Microscopy (FESEM) to verify the presence of the main nanostructures: nanopores, nanotubes, and nanograss. Raman spectroscopy was used for optical characterization in order to identify the changes in the signal of the E_(g)(v6) vibrational mode. It was observed the Raman E_(g)(v6) vibrational mode suffers a redshift at the initial anodization stage with the contribution of the stress between the substrate-oxide layer and the stoichiometry defects. The diameter and tube length have a strong correlation with the oxide thickness (ascendant slope), moreover, this oxide is compared and related to the Raman intensity of the E_(g)(v6) mode, from this fact, it is easy to define some time periods and a voltage range for each titania nanostructures observed.