Exploring phonon transport in complex thermoelectric materials via diffuse scattering

• Grant number: 24/08497-6
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate (Direct)
• Start date: September 02, 2024
• End date: September 01, 2025
• Field of knowledge: Physical Sciences and Mathematics - Physics - Condensed Matter Physics
• Principal Investigator: Sérgio Luiz Morelhão
• Grantee: Rafaela Felix da Silva Penacchio
• Supervisor: Raquel de Almeida Ribeiro
• Host Institution: Instituto de Física (IF). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Institution abroad: Ames National Laboratory, United States
• Associated to the scholarship: 21/01004-6 - Dynamic X-ray diffraction with advanced synchrotron radiation sources: methodologies for applications in biological and material systems technological, BP.DD

Abstract

In this BEPE project, we propose to investigate the physical properties of complex materials, focusing mainly on those relevant to thermoelectric performance, namely electrical resistivity, heat capacity, thermopower, thermal conductivity, and phonon dispersion relations. The latter, in particular, will be investigated through the thermal diffuse scattering of synchrotron X-rays in reflection geometry. While this technique has been successfully applied to simple material systems, such as MgO buffers, its application to more complex systems poses significant challenges. Here, we will first investigate Ce1´La´Fe4X12 (X = P and Sb) skutterudites, a class of materials with promising thermoelectric applications, chemical stability at high temperatures, and relatively low cost. Recent lattice-dynamics calculations have shown that the vibrational properties of lightweight cage compounds (X = P) are highly dependent on filler R, shedding light on why the CeFe4P12 compound has consistently been observed as more suited for thermoelectric applications. However, given the approximations involved in those calculations, experimental verification of such predictions, as proposed in this project, is essential. This internship is proposed to take place at the ISU-Ames Laboratory, a top-level national laboratory dedicated to interdisciplinary research, where the complex materials will be synthesized and characterized, with diffuse scattering measurements planned to be conducted at synchrotron sources, such as APS (Advanced Photon Source) and SIRIUS (33-BM and EMA beamlines, respectively).