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Microstructural Evolution in Spinodal Half-Heusler Thermoelectrics

  • Spinodal Zr0.4Hf0.6Ni1.15Sn half-Heusler thermoelectrics are synthesized and aged. The complex microstructure due to the spinodal decomposition is investigated by powder X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). By Rietveld refinements, it is confirmed that excess Ni atoms in the arc-melted and spark-plasma-sintered half-Heusler matrix prefer to form nanoscale/ submicron Heusler precipitates via spinodal decomposition and growth during the aging at 1173 K. Such phase separation changes the band gap of semiconductors, reduces the thermal conductivity drastically and improves the performance of thermoelectrics. As a result, a more than 50 % improvement of the ZT value on the unaged specimens was achieved.

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Metadaten
Author:Jian Feng
Referee:Prof. Dr. A. Weidenkaff, Prof. Dr. Dr. h.c. G. Schmitz, Dr. H. Näfe
Document Type:Diploma Thesis
Language:English
Year of Completion:2014
Publishing Institution:Hochschule Heilbronn
Granting Institution:Universität Stuttgart
Date of final exam:2014/12/30
Release Date:2017/05/31
Tag:Thermoelektrik
GND Keyword:Thermoelektrik
Pagenumber:58 Seiten
DDC classes:600 Technik, Medizin, angewandte Wissenschaften
Access Right:Frei zugänglich
Licence (German):License LogoCreative Commons - Namensnennung-Nicht kommerziell-Keine Bearbeitung