Anomalous structural disorder and distortion in metal-to-insulator-transition Ti2O3
作者： In-Hui Hwang , Bingzhi Jiang , Zhenlan Jin , Chang-In Park , Sang-Wook Han
DOI: 10.1063/1.4939290
关键词: Extended X-ray absorption fine structure 、 Band gap 、 Condensed matter physics 、 X-ray absorption fine structure 、 Metal–insulator transition 、 Rietveld refinement 、 Bond length 、 Impurity 、 X-ray crystallography 、 Materials science
摘要: Mott proposed that impurity bands in corundum-symmetry Ti2O3 at high temperatures caused a collapse the bandgap. However, origin of has not yet been clarified. We examine local structural properties metal-to-insulator-transition using in-situ x-ray absorption fine structure (XAFS) measurements Ti K edge temperature range from 288 to 739 K. The powder is synthesized by chemical reaction method. X-ray diffraction (XRD) with Rietveld refinement demonstrate single-phased R-3c symmetry without additional distortion. Extended-XAFS combined XRD reveals zigzag patterned position and an anomalous disorder Ti-Ti pairs, accompanied bond length expansion pairs along c-axis for T > 450 K. distortion atoms would induce levels band gap between 3d a1g egπ bands, resulting
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