Dual behavior of excess electrons in rutile TiO2

Abstract

The behavior of electrons in the conduction band of TiO2 and other transition-metal oxides is key to the many applications of these materials. Experiments seem to produce conflicting results: optical and spin-resonance techniques reveal strongly localized small polarons, while electrical measurements show high mobilities that can only be explained by delocalized free electrons. By means of hybrid functional calculations we resolve this apparent contradiction and show that small polarons can actually coexist with delocalized electrons in the conduction band of TiO2, the former being energetically only slightly more favorable. We also find that small polarons can form complexes with oxygen vacancies and ionized shallow-donor impurities, explaining the rich spectrum of Ti${}^{3+}$ species observed in electron spin resonance experiments.

References in corpus (1)

• Polaronic hole-trapping in doped $\mathrm{BaBi}{\mathrm{O}}_3$

Cited by in corpus (20)

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• Coexistence of trapped and free excess electrons in SrTiO3
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• First-principles DFT+GW study of oxygen vacancies in rutile TiO2
• First-Principles Supercell Calculations of Small Polarons with Proper Account for Long-Range Polarization Effects
• Interplay between Ferroelectricity and Metallicity in BaTiO${}_3$
• Small Polarons in Transition Metal Oxides
• Disorder-induced electron and hole trapping in amorphous TiO2
• First-principles embedded-cluster calculations of the neutral and charged oxygen vacancy at the rutile TiO${}_2$(110) surface
• On the accuracy of the HSE hybrid functional to describe many-electron interactions and charge localization in semiconductors
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• Polaron-induced phonon localization and stiffening in rutile TiO${}_2$
• The color center singlet state of oxygen vacancies in TiO${}_2$
• Investigating the high-temperature thermoelectric properties of n-type rutile TiO${}_2$
• Ambipolar Property of Isolated Hydrogen in Oxide Materials Revealed by Muon
• Polaronic nature of a muonium-related paramagnetic center in SrTiO${}_3$