title: Structural stability of a golden semiconducting orthorhombic polymorph of Ti2O3 under high pressures and high temperatures.
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 to 0.20-0.46 Ω cm. Conventional near-infrared absorption spectroscopy established the absence of energy gaps above 0.25 eV.
authors.affiliation: Bayerisches Geoinstitut, Universität Bayreuth, Bayreuth, Germany. sergey.ovsyannikov@uni-bayreuth.de
authors.forename: Sergey V
authors.initials: SV
authors.lastname: Ovsyannikov
authors.forename: Xiang
authors.initials: X
authors.lastname: Wu
authors.forename: Vladimir V
authors.initials: VV
authors.lastname: Shchennikov
authors.forename: Alexander E
authors.initials: AE
authors.lastname: Karkin
authors.forename: Natalia
authors.initials: N
authors.lastname: Dubrovinskaia
authors.forename: Gaston
authors.initials: G
authors.lastname: Garbarino
authors.forename: Leonid
authors.initials: L
authors.lastname: Dubrovinsky
mesh_terms: D003198:Computer Simulation; D003460:Crystallization / Q000379:methods*; D006358:Hot Temperature; D008956:Models, Chemical; D010087:Oxides / Q000138:chemical synthesis / Q000737:chemistry*; D011312:Pressure; D012666:Semiconductors; D013059:Spectrum Analysis, Raman / Q000379:methods; D014025:Titanium / Q000737:chemistry*; D014961:X-Ray Diffraction / Q000379:methods
chemical_list: D010087:Oxides; D014025:Titanium