Published January 1, 2016
| Version v1
Journal article
Open
Determination of the local structure of CsBi4-xPbxTe6 (x=0, 0.5) by X-ray absorption spectroscopy
Creators
- 1. Okayama Univ, Res Inst Interdisciplinary Sci, Okayama 7008530, Japan
- 2. Waseda Univ, Dept Appl Phys, Tokyo 1698555, Japan
- 3. Japan Synchrotron Radiat Res Inst, Res & Utilizat Div, Kouto, Hyogo 6795148, Japan
- 4. Elettra Sincrotrone Trieste, Str Statale 16,Km 163-5, Trieste, Italy
- 5. Natl Inst Mat Sci, Tsukuba, Ibaraki 3050047, Japan
- 6. Univ Roma La Sapienza, Dipartimento Fis, Piazzale Aldo Moro 5, I-00185 Rome, Italy
Description
We have studied the local structure and valence electronic unoccupied states of thermoelectric CsBi4Te6 and superconducting CsBi3.5Pb0.5Te6 (T-c similar to 3 K) by extended X-ray absorption fine structure (EXAFS) and X-ray absorption near edge structure (XANES) measurements. The Bi-L-3 edge EXAFS reveals wide Bi-Te distance distribution for both compounds indicating complex atomic arrangements in the studied system. The mean square relative displacements (MSRDs) of the Bi-Te bond distances appear largely increased in Pb substituted system due to larger overall local disorder, however, one of the Bi-Te bonds shows a reduced disorder. On the other hand, the Bi-L-3 edge XANES is hardly affected by Pb substitution while the Te-L-1 edge XANES reveals increased density of unoccupied Te 5p states. This suggests that the carriers introduced by the Pb substitution in CsBi4-xPbxTe6 preferentially goes on Te sites. Similarly, the Cs-L-3 edge XANES also shows small changes due to Pb-substitution and reduced local disorder indicated by the reduced width of the Cs-L3 edge white line. We have also shown that the X-ray photoemission spectroscopy (XPS) measurements on various electronic core levels are in a qualitative agreement with the XANES results. These findings are consistent with carrier doping and a reduced disorder in one direction to be likely factors to drive the thermoelectric CsBi4Te6 into a bulk superconductor by Pb-substitution in CsBi4-xPbxTe6.
Files
bib-1b2214c4-ac95-4798-912a-10469c5c6914.txt
Files
(356 Bytes)
| Name | Size | Download all |
|---|---|---|
|
md5:45e3fc0ab3370322c7e7c6d97cca9ef4
|
356 Bytes | Preview Download |