The influence of the mixed phase (Ti–TiO2(A): TiO2(R)) on the optical band gap of TiO2 nanotubes heat treated at different temperatures

• Published in: Journal of materials research Vol. 38; no. 14; pp. 3446 - 3457
• Main Authors: Zalouk, D., Hatem, D., Hocine, D., Belkaid, M. S., Hadjersi, T., Kebbati, Y., Boudinar, S.
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 28.07.2023; Springer Nature B.V; Springer
• Subjects: Annealing; Applied and Technical Physics; Biomaterials; Carrier density; Chemistry and Materials Science; Current carriers; Energy gap; Heat treatment; Inorganic Chemistry; Materials Engineering; Materials research; Materials Science; Nanoparticles; Nanotechnology; Nanotubes; Sciences of the Universe; Substrates; Titanium dioxide; nanotubes; R; Mott-Schottky; Resistivity; Annealing temperature; Band gap; TiO; (A)–TiO; Mixed phase (Ti–TiO; Anodization; Mixed phase (Ti-TiO2(A)-TiO2(R)); TiO2 nanotubes
• ISSN: 0884-2914; 2044-5326
• DOI: 10.1557/s43578-023-01027-4

Highly ordered TiO 2 nanotubes (NTs) were synthesized by electrochemical anodization than annealed at different temperatures between 300 and 900 °C for 3 h. The elaborated NTs adhere well to the Ti substrate over the annealing temperature range of 300–600 °C. The TiO 2 NTs morphology begins to gradually evolve for temperatures up to 700 °C and approaches that of nanoparticles until the latter become predominant at T above 800 °C. Reflection measurements show that the NTs present reflection of 7% at 600 °C, corresponding to the lowest band gap 2.59 eV. This can be related to the presence of the mixed phase (Ti–TiO 2(A) –TiO 2(R)) .The charge carrier density decreases from 2.34 × 10 +21 to 3.61 × 10 +13  cm −3 when the annealing temperature increases, that accompanied by a reduction in the resistivity from 142.23 to 29.56Ω.cm which is adequate to photo anode application. Graphical abstract