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MM: Fachverband Metall- und Materialphysik

MM 29: Poster II

MM 29.35: Poster

Dienstag, 19. März 2024, 17:00–19:00, Poster B

Metavalent bonding: A universal strategy to enhance the thermoelectric performance of GeSe alloys — •Xin Zhong, Yuan Yu, and Matthias Wuttig — I. Institute of Physics (IA), RWTH Aachen University, Sommerfeldstraße 14, 52074, Aachen, Germany

Generating electricity in a sustainable and environmentally friendly manner is currently a topic of great concern. Thermoelectric materials, capable of directly converting heat into electricity through temperature differences, provide an effective means to harness waste heat. Doping is a practical approach to enhance thermoelectric properties, even for materials with initially poor thermoelectric performance, such as GeSe. Previous studies have demonstrated that the successful doping effects in GeSe can only be enabled by forming a metavalently bonded phase. Effective dopants such as AgSbSe₂ and AgBiTe₂ that can enable such a chemical bonding transition of GeSe from covalent to metavalent are confined in a special region of a map, where metavalently bonded compounds prevail. Yet, the universality of this concept has to be verified. Here we select PbTe from this metavalent region to alloy with GeSe. We prove that a new metavalently bonded GeSe phase can be formed with proper contents of PbTe alloying using atom probe tomography, optical property measurements, and density functional theory calculations. The resulting metavalently bonded alloy shows greatly improved thermoelectric performance by a factor of more than ten. We prove that such metavalent bonding can be a universal strategy for designing high-performance chalcogenide thermoelectrics.

Keywords: thermoelectrics; atom probe tomography; microstructure; metavalent bonding; GeSe