Electrical properties and charge compensation mechanisms of Cr-doped rutile, TiO2

Dang, Y ORCID: 0000-0002-0140-0140, Phuah, XL, Wang, H, Yang, B, Wang, H and West, AR (2021) Electrical properties and charge compensation mechanisms of Cr-doped rutile, TiO2 Physical Chemistry Chemical Physics, 23 (38). pp. 22133-22146. ISSN 1463-9076, 1463-9084

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Abstract

Cr-doped rutile, Ti<inf>1−x</inf>Cr<inf>x</inf>O<inf>2−x/2−δ</inf>, powders and ceramics with 0 ≤x≤ 0.05 were prepared by solid state reaction and sintered at 1350 °C. Cr distribution is homogeneous with no evidence of either segregation or crystallographic shear plane formation. For highxcompositions, >∼0.01, Cr substitution is charge-compensated ionically by oxygen vacancies with two Cr³⁺ions for each vacancy and the materials are electronically insulating. For lowxcompositions, the materials are semiconducting. This is attributed to a new charge compensation mechanism involving Ti³⁺ions created in response to the local electroneutrality requirement for two trivalent cations to be in close proximity to each oxygen vacancy. At very low dopant concentrations, ≪0.01, the dopants are well-separated and instead, some Ti³⁺ions act as a second dopant to preserve local electroneutrality. For intermediatexcompositions, a core-shell structure is proposed consisting of semiconducting grain interiors containing Ti³⁺ions surrounded by a more insulating shell with Cr³⁺ions as the only acceptor dopant. Lattice parameters show unusual, non-linear Vegard's law behaviour characterised by a maximum in cell volume at intermediatex∼ 0.005, that is attributed to the composition-dependent presence of Ti³⁺ions.

Item Type:	Article
Uncontrolled Keywords:	40 Engineering, 34 Chemical Sciences
Divisions:	Faculty of Science & Engineering > School of Physical Sciences
Depositing User:	Symplectic Admin
Date Deposited:	06 Dec 2021 11:43
Last Modified:	01 Mar 2026 10:56
DOI:	10.1039/d1cp01735g
Open Access URL:	https://pubs.rsc.org/en/content/articlelanding/202...
Related Websites:	Author Publisher
URI:	https://livrepository.liverpool.ac.uk/id/eprint/3144759
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