Electronic absorption by Ti 3+ ions and electron delocalization in synthetic blue rutile

Fluorine- and Niobium-Doped TiO2: Chemical and Spectroscopic Properties of Polycrystalline n-Type-Doped Anatase

“…The presence of the first absorption feature centred at c.a. 1000 nm is in agreement with data reported in the literature 68,69 and becomes much more evident after contacting the sample with oxygen at room temperature ( Fig. 9a').…”

“…Broad optical spectra for reduced TiO 2 are reported in the literature, in particular in the case of rutile 68 , which are attributed to the presence of Ti 3+ centres responsible for the typical blue colour of these reduced systems. Once again, however, the n-type systems analysed in this work show a remarkable difference with respect to the pure material.…”

Optical absorption of polydisperse TiO2: Effect of surface doping by transition metal cations

“…Closely located bands centred at 2.95 eV (420 nm) and 2.75 eV (450 nm) have earlier been observed by Ghosh et al [11] under thermal excitation of the rutile single crystals. Khomenko et al [12] have also observed weak absorption bands between 2.3 eV and 2.9 eV and assigned them to d-d transitions associated with Ti 3+ localised states. These weak optical absorption bands may also be assigned to electron transitions from different trapping levels associated with oxygen vacancies [13].…”

Experimental Validation of the Importance of Thermally Stable Bulk Reduction States in TiO2for Gas Sensor Applications

“…This type of visible-light absorption is related to the reduction states in TiO 2 (e.g., singleelectron-trapped oxygen vacancies (V o • ) and Ti 3 ＋ species). [3][4][5][6][7][8][9][10][11][12][13]16] The stronger visible-light absorption for TiO 2 -500 indicates the larger amount of reduction states in TiO 2 -500. The optical properties are in agreement with the colors (Figure 5b) of TiO 2 -500 (dark gray), TiO 2 -600 (light gray) and R-TiO 2 (white).…”

“…[3][4][5][6][7][8][9][10][11][12][13] The presence of reduction states has been theoretically and/or experimentally confirmed to play an important role in modifying energy band and surface DOI: 10.6023/A12030002 structures of TiO 2 , [9,13] and in varying its magnetic, [7,8] electronic [11] and photocatalytic behavior. [11][12][13] Gas-sensing is a typical property of metal oxide semiconductor materials such as titania, and this property is associated with conductivity variation, which is induced by the interaction between the adsorbed oxygen on the surface of the semiconductor and the gas molecules to be detected.…”