Regensburg 2025 – wissenschaftliches Programm
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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur
KFM 14: Poster
KFM 14.20: Poster
Mittwoch, 19. März 2025, 17:00–18:30, P1
Characterizing Domains in GeTe using Atom Probe Tomography — •Jan Köttgen1, Maria Häser1, Lina Jäckering1, Julian Pries1, Carl-Friedrich Schön1, Pengfei Cao3, Yuan Yu1, and Matthias Wuttig1,2 — 1I. Institute of Physics (IA), RWTH Aachen University, Germany — 2Peter Grünberg Institute - JARA-Institute Energy Efficient Information Technology (PGI-10), Jülich, Germany — 3Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons ER-C, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
The thermoelectric GeTe undergoes a solid-state phase transition from its cubic to its rhombohedral crystal structure when cooled from the melt to room temperature. This phase transformation results in domains. In this study a polycrystalline GeTe bulk sample was investigated using atom probe tomography (APT), which enables the determination of the sample*s stoichiometry with atomic resolution. The APT analysis revealed that different domains evaporate with different probabilities of multiple events (PME). Metavalent solids such as GeTe are known generally to exhibit a high PME in APT. Our experiments additionally show an anisotropy between different grains as observed in the PME. Using a correlative approach involving TEM, EBSD, AFM, SNOM, and DFT calculations, this effect can be attributed to an expansion of the unit cell and a concomitant change of the dielectric function. Our experiments open new avenues for atom probe tomography as a tool to investigate domains and the atomic distribution simultaneously crucial to improve the performance of thermoelectrics.
Keywords: Thermoelectic; GeTe; Atom Probe Tomography; Domains; Metavalent