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Nanophase separation in CoSb-based half-Heusler thermoelectrics : A multiscale simulation study

Title data

Miranda Mena, Joaquin ; Schoberth, Heiko G. ; Gruhn, Thomas ; Emmerich, Heike:
Nanophase separation in CoSb-based half-Heusler thermoelectrics : A multiscale simulation study.
In: Physica Status Solidi A. (2015) . - pp. 706-715.
ISSN 1521-396X
DOI: https://doi.org/10.1002/pssa.201532457

Official URL: Volltext

Abstract in another language

If cooled down from high temperatures, some half-Heusler alloys based on CoTiSb show a spontaneous phase separation into coexisting domains. In thermoelectric applications, this domain structure is beneficial for the efficiency because it reduces the lattice thermal conductivity, which increases the figure of merit. For this reason, it is of great relevance to understand the details of the demixing phenomenon. We combine density functional theory, Monte Carlo simulations, and mean field calculations in order to investigate the demixing behavior of CoTi1−xZxSb with Z= Sc, V, Cr, Mn, Fe, Cu. Based on the calculations we present phase diagrams, which provide the coexistence region of the materials. Density functional theory results show that for low temperatures, demixed states are more stable than mixed ones. With the help of an ab initio-based cluster expansion of the configurational energy, we can perform mean field calculations and Monte Carlo simulations to study half-Heusler alloys at higher temperature on a larger scale. With the mean field calculations, the coexistence region and the spinodal can be determined for regions far from the critical point. The Monte Carlo simulations help to improve the coexistence lines and provide insights into structures formed in alloys that are quenched into the coexistence region.

Further data

Item Type: Article in a journal
Refereed: Yes
Keywords: ab initio calculations; Cluster expansion; CoTiSb; domains; half-Heusler alloys; thermoelectric materials
Institutions of the University: Faculties > Faculty of Engineering Science > Chair Material and Process Simulations
Faculties > Faculty of Engineering Science > Former Professors > Chair Material and Process Simulations - Univ.-Prof. Dr.-Ing. Heike Emmerich
Faculties
Faculties > Faculty of Engineering Science
Faculties > Faculty of Engineering Science > Former Professors
Result of work at the UBT: Yes
DDC Subjects: 500 Science > 530 Physics
500 Science > 540 Chemistry
600 Technology, medicine, applied sciences > 620 Engineering
Date Deposited: 14 Mar 2016 09:52
Last Modified: 08 May 2020 09:45
URI: https://eref.uni-bayreuth.de/id/eprint/31724