Electronic Structure, Optical and Magnetic Properties of Oxygen-Deficient Gray TiO[sub.2–δ]

• Published in: Inorganics 2022-10, Vol.10 (11)
• Main Authors: Opra, Denis P, Sokolov, Alexander A, Sinebryukhov, Sergey L, Tkachenko, Ivan A, Ziatdinov, Albert M, Gnedenkov, Sergey V
• Format: Article
• Language: English
• Subjects: Analysis; Chemical synthesis; Magnetic properties; Methods; Optical properties; Structure; Titanium dioxide
• ISSN: 2304-6740
• DOI: 10.3390/inorganics10110184

The gray-colored oxygen-deficient TiO[sub.2–δ] (B) nanobelts have been synthesized through a combination of the hydrothermal method followed by an ion exchange process and vacuum annealing. Electron paramagnetic resonance reveals an existence of F-centers in the form of electron-trapped oxygen vacancies within the anionic sublattice of the gray bronze TiO[sub.2] that induces its colouration. The diffuse reflectance spectroscopy showed that the formation of oxygen vacancies into TiO[sub.2] (B) significantly increases its absorption intensity in both visible and near infrared ranges. The band gap of TiO[sub.2] (B) with anionic defects is equal to 3.03 eV (against 3.24 eV for white TiO[sub.2] (B) treated in air). Room temperature ferromagnetism associated with the defects was detected in gray TiO[sub.2–δ] (B), thus indicating it belongs it to the class of dilute magnetic oxide semiconductors. It was found that in the low-temperature range (4 K), the magnetic properties of vacuum annealed TiO[sub.2] (B) do not differ from those for TiO[sub.2] (B) treated in air. We hope that the findings are defined here make a contribution to further progress in fabrication and manufacturing of defective TiO[sub.2] -based nanomaterials for catalysis, magnetic applications, batteries, etc.