Energy Levels of Iron Group Impurities in TiO<sub>2</sub>

Mizushima, Koichi; Tanaka, Mitsuaki; Iida, Shūichi

doi:10.1143/jpsj.32.1519

Cited by 75 publications

(45 citation statements)

References 5 publications

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“…In the rutile case this brings the Cr 3d level to a position of 0.3 eV above the top of the valence band. This is in agreement with an early electron spin resonance study, backed up by energy level calculations, by Mizushima et al [23,24] that found the Cr 3+ impurity levels in rutile TiO 2 to be about 0.35 eV above the valence band. Those samples were prepared by high-temperature diffusion of Cr into TiO 2 single crystals; the doping levels were much lower (0.001 -0.01 at.%) than in the samples considered here.…”

Section: Electronic Structuresupporting

confidence: 91%

Growth of Cr-doped TiO2 films in the rutile and anatase structures by oxygen plasma assisted molecular beam epitaxy

et al. 2005

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Section: Electronic Structuresupporting

confidence: 91%

Growth of Cr-doped TiO2 films in the rutile and anatase structures by oxygen plasma assisted molecular beam epitaxy

et al. 2005

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“…There is a the valence band and 1 eV below the conduction band. This was suggested by ESR measurements on copper-doped TiO2 (15). In these conditions the 2.2 eV peak would correspond to the transition from 1 tlg of oxygen to the copper state and the higher energy peak to the transition from the copper state to 3eg of titanium.…”

Section: Discussionmentioning

confidence: 80%

Influence of Copper Addition on Optical Properties of TiO2

Blondeau¹,

Froelicher²,

Froment³

et al. 1979

J. Electrochem. Soc.

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Cu-doped TiO~ could be considered as a better absorber of sunlight for solar energy conversion. The Cu-doped TiO2 has been prepared by anodic oxidation of a Ti-2.5% Cu alloy. The structural properties of these anodic oxides are examined by electron microdiffraction, XPS, and nuclear microanalysis. The optical properties of both the Ti-Cu alloy and the anodic films have been determined as functions of the thickness of the oxides. It is concluded that Cu doping o~ TiO2 creates an extra state in the forbidden gap of TiO2 which gives two extra peaks in the absorption spectrum of the oxide. But for solar energy applications, the preparation of the doped oxide by anodic oxidation is not suitable because one does not control the level of impurity.Titanium dioxide electrodes created a great interest in the field of semiconductor-electrolyte interfaces when it was shown by Fijishima and Honda (1). that water photoelectrolysis was possible without degradation or decomposition of the semiconductor electrode. For solar applications, however, TiO2 is not suitable because the bandgap of this oxide is 3 eV (410 nm) too far away in the u.v. region to significantly absorb the solar energy. A great amount of work has been done to find the right semiconductor electrode with a bandgap around 2 eV (620 nm) and stability comparable to the TiO2 electrode; two review articles (2, 3) summarize these works. Among the numerous materials or combinations of materials which have been tested to do this water photoe]ectrolysis, TiO2 remains high in the list since it is the most stable material for a long period of time. So the problem is to decrease the TiO~ bandgap or increase the optical absorption in the visible region by increasing the number of defects (holes, vacancies, etc.). Both approaches have been tested on specific systems; Ghosh and Maruska (4) have reported water photoelectrolysis using visible light on a Cr-doped TiO2 electrode, Augustinski et al. (5) have also reported results for TiO~ doped with 6% A120~.Keeping in mind the possible applications of this study we have chosen Cu to fill the bandgap of TiO2. The preparation of Cu-doped TiO2 was made by anodic oxidation of a Ti-Cu alloy which is commercially available and has good mechanical properties. Our purpose is also to show the importance of the knowledge of the optical indexes of both the substrate and the semiconductor film to determine the bandgap shift and the absorption variations due to the incorporation of copper.

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“…Mizushima et al have reported the energy levels of 3d TM impurities in TiO 2 , which were experimentally determined or theoretically calculated based on the experimental data of crystal field parameters. 4) Experimentally, the formation of localized TM dopant states have been studied by electron spin resonance in TiO 2 crystals where the Fermi level position was adjusted by Li doping. 5) In this paper, we report on a systematic photoemission spectroscopy study of TM-doped (TM = V, Cr, Mn, Fe, Co, and Ni) TiO 2 films grown on Nb-doped TiO 2 single crystal substrates for various film thicknesses and including a non-doped TiO 2 /Nb:TiO 2 sample as a reference.…”

Section: Introductionmentioning

confidence: 99%

Chemical trend of Fermi-level shift in transition metal-doped TiO2 films

Matsumoto¹,

Katayama²,

Abe³

et al. 2010

J. Ceram. Soc. Japan

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The effect of doping a wide range of transition metals (TMs) including V, Cr, Mn, Fe, Co, and Ni into rutile TiO 2 films grown on Nb-doped TiO 2 (110) single-crystal substrates was investigated by photoemission spectroscopy and X-ray absorption spectroscopy. For all TM-doped TiO 2 films, the Ti 2p and O 1s core levels were similarly shifted to lower binding energies with increasing film thickness and the shifts were similarly saturated at a film thickness of about 15 nm. These peak shifts could be interpreted in terms of the Fermi level shift, indicating that dopants trap excess electrons from the Ti 3d band like acceptors. The present systematic data revealed that the magnitude of the saturated Fermi level shift correlates well with the effective charge transfer energy.

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Energy Levels of Iron Group Impurities in TiO₂

Cited by 75 publications

References 5 publications

Growth of Cr-doped TiO2 films in the rutile and anatase structures by oxygen plasma assisted molecular beam epitaxy

Growth of Cr-doped TiO2 films in the rutile and anatase structures by oxygen plasma assisted molecular beam epitaxy

Influence of Copper Addition on Optical Properties of TiO2

Chemical trend of Fermi-level shift in transition metal-doped TiO2 films

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Energy Levels of Iron Group Impurities in TiO2

Cited by 75 publications

References 5 publications

Growth of Cr-doped TiO2 films in the rutile and anatase structures by oxygen plasma assisted molecular beam epitaxy

Growth of Cr-doped TiO2 films in the rutile and anatase structures by oxygen plasma assisted molecular beam epitaxy

Influence of Copper Addition on Optical Properties of TiO2

Chemical trend of Fermi-level shift in transition metal-doped TiO2 films

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Energy Levels of Iron Group Impurities in TiO₂