Anomalous structural disorder and distortion in metal-to-insulator-transition Ti{sub 2}O{sub 3}

Journal Article · Thu Jan 07 00:00:00 EST 2016 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4939290· OSTI ID:22494866

Hwang, In-Hui; Jin, Zhenlan; Park, Chang-In; Han, Sang-Wook ^[1]; Jiang, Bingzhi ^[2]

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1. Department of Physics Education and Institute of Fusion Science, Jeonbuk(Chonbuk) National University, Jeonju 561-756 (Korea, Republic of)
2. Department of Physics, Yanbian University, Yanji 133002 (China)

Mott proposed that impurity bands in corundum-symmetry Ti{sub 2}O{sub 3} at high temperatures caused a collapse in the bandgap. However, the origin of the impurity bands has not yet been clarified. We examine the local structural properties of metal-to-insulator-transition Ti{sub 2}O{sub 3} using in-situ x-ray absorption fine structure (XAFS) measurements at the Ti K edge in the temperature range from 288 to 739 K. The Ti{sub 2}O{sub 3} powder is synthesized by using a chemical reaction method. X-ray diffraction (XRD) measurements from Ti{sub 2}O{sub 3} with a Rietveld refinement demonstrate a single-phased R-3c symmetry without additional distortion. Extended-XAFS combined with XRD reveals a zigzag patterned Ti position and an anomalous structural disorder in Ti-Ti pairs, accompanied by a bond length expansion of the Ti-Ti pairs along the c-axis for T > 450 K. The local structural distortion and disorder of the Ti atoms would induce impurity levels in the band gap between the Ti 3d a{sub 1g} and e{sub g}{sup π} bands, resulting in a collapse of the band gap for T > 450 K.

• OSTI ID: 22494866
• Journal Information: Journal of Applied Physics, Vol. 119, Issue 1; Other Information: (c) 2016 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ABSORPTION
ABSORPTION SPECTROSCOPY
BOND LENGTHS
CHEMICAL REACTIONS
CORUNDUM
ELECTRONIC STRUCTURE
FINE STRUCTURE
IMPURITIES
METALS
SYMMETRY
TEMPERATURE RANGE 0400-1000 K
TITANIUM OXIDES
X RADIATION
X-RAY DIFFRACTION
X-RAY SPECTROSCOPY