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Developing Contacting Solutions for Mg2Si1–xSnx-Based Thermoelectric Generators: Cu and Ni45Cu55 as Potential Contacting Electrodes

Ayachi, Sahar and Castillo Hernandez, Gustavo and Pham, Ngan Hoang and Farahi, Nader and Müller, Eckhard and de Boor, Johannes (2019) Developing Contacting Solutions for Mg2Si1–xSnx-Based Thermoelectric Generators: Cu and Ni45Cu55 as Potential Contacting Electrodes. ACS Applied Materials and Interfaces. American Chemical society (ACS). DOI: 10.1021/acsami.9b12474 ISSN 1944-8244

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Abstract

Magnesium silicides can be used for thermoelectric energy conversion as high values of figure of merit zT were obtained for n-type (1.4 at 500 °C) and p-type (0.55 at 350 °C) materials. This, however, needs to be complemented by low resistive and stable contacting to ensure long-term thermogenerator operation and minimize losses. In this study, we selected Cu and Ni45Cu55 as contacting electrodes for their high electrical conductivity, similar coefficient of thermal expansion (CTE), and good adhesion to Mg2(Si,Sn). Both electrodes were joined to Mg2Si0.3Sn0.7 pellets by hot pressing in a current-assisted press. Microstructural changes near the interface were analyzed using SEM/EDX analysis, and the specific electrical contact resistance rc was estimated using a traveling potential probe combined with local Seebeck scanning. Good contacting was observed with both electrode materials. Results show low rc with Cu, suitable for applications, for both n- and p-type silicides (<10 μΩ·cm2), with the occurrence of wide, highly conductive diffusion regions. Ni45Cu55 joining also showed relatively low rc values (∼30 μΩ·cm2) for n- and p-type but had a less inhomogeneous reaction layer. We also performed annealing experiments with Cu-joined samples at 450 °C for 1 week to investigate the evolution of the contact regions under working temperatures. rc values increased (up to ∼100 μΩ·cm2) for annealed n-type samples but remained low (<10 μΩ·cm2) for p-type. Therefore, Cu is a good contacting solution for p-type Mg2(Si,Sn) and a potential one for n-type if the diffusion causing contact property degradation can be prevented.

Item URL in elib:https://elib.dlr.de/130575/
Document Type:Article
Title:Developing Contacting Solutions for Mg2Si1–xSnx-Based Thermoelectric Generators: Cu and Ni45Cu55 as Potential Contacting Electrodes
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Ayachi, SaharGerman aerospace center, institute of materials research, köln, germanyUNSPECIFIED
Castillo Hernandez, GustavoGerman aerospace center, institute of materials research, köln, germanyUNSPECIFIED
Pham, Ngan HoangGerman aerospace center, institute of materials research, köln, germanyUNSPECIFIED
Farahi, NaderGerman aerospace center, Institute of materials research, Köln, GermanyUNSPECIFIED
Müller, EckhardGerman aerospace center, Institute of materials research, Köln, Germany and Institute for inorganic and analytical chemistry, Justus-Liebig-Universität Gießen, Heinrich-Buff-Ring 58, 35392 Gießen, GermanyUNSPECIFIED
de Boor, Johannesgerman aerospace center, institute of materials research, köln, germanyhttps://orcid.org/0000-0002-1868-3167
Date:17 October 2019
Journal or Publication Title:ACS Applied Materials and Interfaces
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In SCOPUS:Yes
In ISI Web of Science:Yes
DOI :10.1021/acsami.9b12474
Publisher:American Chemical society (ACS)
ISSN:1944-8244
Status:Published
Keywords:Thermoelectrics; contacting; interface; electrical contact resistance; annealing
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Transport
HGF - Program Themes:Road Transport
DLR - Research area:Transport
DLR - Program:V ST Straßenverkehr
DLR - Research theme (Project):V - NGC Antriebssystem und Energiemanagement
Location: Köln-Porz
Institutes and Institutions:Institute of Materials Research > Thermoelectric Materials and Systems
Deposited By: Yasseri, Mohammad
Deposited On:15 Nov 2019 15:18
Last Modified:15 Nov 2019 15:18

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