Original Article Thermal transport properties for unveiling the mechanism of BiSbTe alloys in thermoelectric generation: A glance from synchrotron radiation Bi L 3 -XAFS Shaimaa Elyamny a,* , N.G. Imam b , Giuliana Aquilanti c , Humberto Cabrera d , Abd El-Hady B. Kashyout a a Electronic Materials Research Department, Advanced Technology and New Materials Research Institute, City of Scientific Research and Technological Applications (SRTA-City), New Borg El-Arab City, P.O. Box 21934, Alexandria, Egypt b Experimental Physics Department (Solid State Lab.), Nuclear Research Center, Egyptian Atomic Energy Authority, Cairo, 13759, Egypt c Elettra - Sincrotrone Trieste, Strada Statale 14 e Km 163,5 in AREA Science Park, 34149, Basovizza, Trieste, Italy d Optics Lab, STI Unit, The Abdus Salam International Centre for Theoretical Physics, Trieste, 34151, Italy article info Article history: Received 28 December 2021 Accepted 15 March 2022 Available online 26 March 2022 Keywords: Antimony doped bismuth telluride Thermoelectric Twin boundary Synchrotron radiation (XANES, EXAFS) Thermal conductivity Local structure abstract For thermal to electric energy conversion, designing a high efficiency thermoelectric ma- terial entails simultaneously optimizing multiple properties of the material. Although it may appear simple to increase electrical power while minimizing thermal losses, the complicated link between these parameters makes optimization difficult, necessitating a more sophisticated approach. The one-pot zone melting method was used to fabricate undoped and Sb doped Bi 2 Te 3 (Bi 2x Sb x Te 3 ; x ¼ 0.0, 0.2, 0.6, and 1.0) in pellets form. X-ray diffraction (XRD), Raman and selected area electron diffraction (SAED) revealed rhombo- hedral polycrystalline nature and a unique high intensity of the E g 2 optical mode according to the nanosheet nature of the alloys as observed in the scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images. Besides, High Resolution TEM (HRTEM) micrographs depicted twin boundary effect with an angle of 120  for Bi 1.8 Sb 0.2 Te 3 alloys, which may enhance the electronic transport and the thermoelectric properties of the fabricated compounds. To obtain selective and detailed local structural information of Bi 2x Sb x Te 3 matrix, synchrotron radiation-based X-ray absorption spectroscopy (XAS) measurements were performed at around Bi L 3 -edge. A significant influence of the Sb/Bi substitution on the local/atomic structure was observed through the gradual elongation of the average in-plane BieSb bond distance. The combination of different off-line structural characterization techniques such as XRD, Raman, SEM, and HRTEM with synchrotron based XAS technique and Laser-Beam Deflection Spectroscopy (BDS) is necessary to fully * Corresponding author. E-mail address: selyamny@srtacity.sci.eg (S. Elyamny). Available online at www.sciencedirect.com journal homepage: www.elsevier.com/locate/jmrt journal of materials research and technology 2022;18:2261 e2272 https://doi.org/10.1016/j.jmrt.2022.03.101 2238-7854/© 2022 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http:// creativecommons.org/licenses/by-nc-nd/4.0/).