Structural stability of a golden semiconducting orthorhombic polymorph of Ti2O3 under high pressures and high temperatures

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Ovsyannikov, Sergey V. ; Wu, Xiang ; Shchennikov, Vladimir V. ; Karkin, Alexander E. ; Dubrovinskaia, Natalia ; Garbarino, Gaston ; Dubrovinsky, Leonid:
Structural stability of a golden semiconducting orthorhombic polymorph of Ti2O3 under high pressures and high temperatures.
In: Journal of Physics: Condensed Matter. Bd. 22 (2010) Heft 37 . - 375402.
ISSN 1361-648X
DOI: https://doi.org/10.1088/0953-8984/22/37/375402

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Abstract

An orthorhombic polymorph of titanium oxide (Ti 2 O 3 ) has been synthesized at high pressure–high temperature (HP–HT) conditions. It has been refined in the Pnma space group and the Th 2 S 3 structural type with the unit cell parameters as follows: a = 7.8248(6) Å, b = 2.8507(4) Å, c = 8.0967(3) Å, V = 180.61(1) Å 3 and Z = 4. The samples of Pnma -Ti 2 O 3 were of a golden colour, in contrast to the conventional black corundum-structured Ti 2 O 3 . The structural stability of this polymorph has been examined by simultaneous Raman and x-ray diffraction studies under high pressure over 70 GPa and high temperature over 2200 K. No phase transformations or chemical reactions have been established. The electrical resistivity of Th 2 S 3 -structured Ti 2 O 3 samples showed a semiconducting behaviour and, at ambient conditions, was equal to0.20–0.46 Ω cm. Conventional near-infrared absorption spectroscopy established the absence of energy gaps above 0.25 eV.