Atomic ordering in cubic bismuth telluride alloy phases at high pressure

DOI: 10.1103/PhysRevB.93.224109

Authors: I. Loa (University of Edinburgh) , J.-w. Bos (Heriot-Watt University) , R. A. Downie (Heriot-Watt University) , K. Syassen (Max-Planck-Institut für Festkörperforschung)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Physical Review B , VOL 93

State: Published (Approved)
Published: June 2016
Diamond Proposal Number(s): 8105

Abstract: Pressure-induced transitions from ordered intermetallic phases to substitutional alloys to semi-ordered phases were studied in a series of bismuth tellurides. By using angle-dispersive x-ray diffraction, the compounds Bi 4 Te 5 , BiTe, and Bi 2 Te were observed to form alloys with the disordered body-centered cubic (bcc) crystal structure upon compression to above 14–19 GPa at room temperature. The BiTe and Bi 2 Te alloys and the previously discovered high-pressure alloys of Bi 2 Te 3 and Bi 4 Te 3 were all found to show atomic ordering after gentle annealing at very moderate temperatures of ∼100 ∘ C . Upon annealing, BiTe transforms from bcc to the B2 (CsCl) crystal-structure type, and the other phases adopt semi-disordered variants thereof, featuring substitutional disorder on one of the two crystallographic sites. The transition pressures and atomic volumes of the alloy phases show systematic variations across the Bi m Te n series including the end members Bi and Te. First-principles calculations were performed to characterize the electronic structure and chemical bonding properties of B2-type BiTe and to identify the driving forces of the ordering transition. The calculated Fermi surface of B2-type BiTe has an intricate structure and is predicted to undergo three topological changes between 20 and 60 GPa.

Subject Areas: Materials


Instruments: I15-Extreme Conditions

Other Facilities: ESRF

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