Regensburg 2019 – scientific programme
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MM: Fachverband Metall- und Materialphysik
MM 6: Topical session (Symposium MM): Correlative and in-situ Microscopy in Materials Research
MM 6.4: Talk
Monday, April 1, 2019, 12:45–13:00, H44
Atom Probe Tomography for Thermoelectric Materials — •Yuan Yu1, Oana Cojocaru-Mirédin1, and Matthias Wuttig1, 2 — 1I. Physikalisches Institut (IA), RWTH Aachen Univeristy, Sommerfeldstraße, 52074 Aachen, Germany — 2JARA-Institut Green IT, JARA-FIT, Forschungszentrum Jülich GmbH and RWTH Aachen University, 52056 Aachen, Germany
Both microstructures and chemical composition of defects, including 0D point defects, 1D dislocations, 2D interfaces, and 3D precipitates, significantly influence the electrical and thermal transport properties of thermoelectric materials. However, determining their three-dimensional chemical composition, with a spatial accuracy of sub-nanometer and chemical sensitivity of ~10 ppm was impossible until the emergence of atom probe tomography (APT). In this work, we summarize the existing studies on local composition of various structural defects in thermoelectric materials using APT. With the chemical information at sub-nanometer scale, the corresponding thermoelectric properties can be better understood. Moreover, APT can distinguish a peculiar bonding mechanism, which is called metavalent bonding being responsible for intrinsic low lattice thermal conductivity, between matrix and defects. This provides a novel method to analyze and adjust the tradeoff between intrinsic bonding and extrinsic defects. Thereby, this precious technique is able to extend the concept of defect engineering and adjust the balance between bonding and defects in thermoelectrics and facilitate the rational design of high-performance thermoelectric materials.