In:
Journal of Applied Physics, AIP Publishing, Vol. 124, No. 6 ( 2018-08-14)
Abstract:
A2B3-type 3D topological insulators, Bi2Te3 and Sb2Te3, have been reported to transform into disordered substitutional alloys under high pressure. However, γ → δ phase transition and the local structure changes around Bi during the formation of the disordered Bi-Te binary alloy in Bi2Te3 still remain unclear. Here, high-pressure X-ray absorption fine structure (XAFS) combined with high-pressure X-ray diffraction has been used to explore the local structural transformations in the three structural phase transitions of Bi2Te3. The Bi L3-X-ray absorbing near edge structure (XANES) spectra of δ-Bi2Te3 clearly showed that a new absorption feature at energy of about 13 465 eV would emerge during the γ → δ phase transition. Through simulation of the XANES spectra by varying the cluster size, we confirmed that the new absorption peak arises from the medium-range order in bcc structure. The Bi L3-EXAFS results in δ phase reveal that the Bi atoms in the third shell exhibit abnormal elongations with pressure until merging with the shrinking Te shell. Our findings indicate a two-step structural transition of the disordered substitutional alloys via an ordered bcc intermediate phase.
Type of Medium:
Online Resource
ISSN:
0021-8979
,
1089-7550
Language:
English
Publisher:
AIP Publishing
Publication Date:
2018
detail.hit.zdb_id:
220641-9
detail.hit.zdb_id:
3112-4
detail.hit.zdb_id:
1476463-5
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