High efficiency Mg<sub>2</sub>(Si,Sn)-based thermoelectric materials: scale-up synthesis, functional homogeneity, and thermal stability

Farahi, Nader; Stiewe, Christian; Truong, Dao Y Nhi; Boor, Johannes de; Müller, Eckhard

doi:10.1039/c9ra04800f

Cited by 33 publications

(51 citation statements)

References 69 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Whether this is due to (local) changes in the composition or is related to defects in the material requires further investigations. However, as such change in TE properties did not happen after annealing non-contacted Mg 2 Si 0.3 Sn 0.7 at 450°C for one month 33 , it can be safely assumed that the observable changes here are due to contacting and continuous inhomogeneous diffusion, and not only annealing.…”

Section: Discussionmentioning

confidence: 90%

See 1 more Smart Citation

Developing Contacting Solutions for Mg₂Si_1–xSn_x-Based Thermoelectric Generators: Cu and Ni₄₅Cu₅₅ as Potential Contacting Electrodes

Ayachi

Hernández

Pham

et al. 2019

ACS Appl. Mater. Interfaces

Self Cite

View full text Add to dashboard Cite

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 Ni 45 Cu 55 as contacting electrodes for their high electrical conductivity, similar coefficient of thermal expansion (CTE) and good adhesion to Mg 2 (Si,Sn). Both electrodes were joined to Mg 2 Si 0.3 Sn 0.7 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 r c was estimated using a travelling potential probe combined with local Seebeck scanning. Good contacting was observed with both electrode materials. Results show low r c with Cu, suitable for application, for both n-type and p-type silicides (< 10 µΩ•cm 2 ), with the occurrence of wide, highly conductive diffusion regions. Ni 45 Cu 55 joining also showed relatively low r c values (~ 30 µΩcm 2 ) 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 one week to investigate the evolution of the contact regions under working temperatures. r c values increased (up to ~ 100 µΩcm 2 ) for annealed n-type samples, but remained low (< 10 µΩcm 2 ) for p-type. Therefore, Cu is a good contacting solution for p-type Mg 2 (Si,Sn), and a potential one for n-type if the diffusion causing contact property degradation can be prevented.

show abstract

Section: Discussionmentioning

confidence: 90%

“…It is also favourable to use similar n-and p-type materials as this simplifies contact development 30 . 33 . N-type samples were initially synthesized with 3% excess Mg to compensate for the Mg evaporation that occurs during the sintering time, which is double the sintering time needed for p-type samples.…”

Section: Introductionmentioning

confidence: 99%

Developing Contacting Solutions for Mg₂Si_1–xSn_x-Based Thermoelectric Generators: Cu and Ni₄₅Cu₅₅ as Potential Contacting Electrodes

Ayachi

Hernández

Pham

et al. 2019

ACS Appl. Mater. Interfaces

Self Cite

View full text Add to dashboard Cite

show abstract

“…The solid solution Mg 2 (Si,Sn) pellets were prepared similarly to what was reported in previously published papers [27,[30][31][32], with the following nominal stoichiometry: Mg 2.06 Si 0.3 Sn 0.665 Bi 0.035 for n-type and Mg 1.98 Li 0.03 Si 0.3 Sn 0.7 for p-type. The n-type composition contains Mg with an excess of 3% in order to compensate for the Mg evaporation occurring during the sintering, due to its longer duration compared to p-type samples.…”

Section: Methodsmentioning

confidence: 99%

Overcoming Asymmetric Contact Resistances in Al-Contacted Mg2(Si,Sn) Thermoelectric Legs

et al. 2021

Self Cite

View full text Add to dashboard Cite

Thermoelectric generators are a reliable and environmentally friendly source of electrical energy. A crucial step for their development is the maximization of their efficiency. The efficiency of a TEG is inversely related to its electrical contact resistance, which it is therefore essential to minimize. In this paper, we investigate the contacting of an Al electrode on Mg2(Si,Sn) thermoelectric material and find that samples can show highly asymmetric electrical contact resistivities on both sides of a leg (e.g., 10 µΩ·cm2 and 200 µΩ·cm2). Differential contacting experiments allow one to identify the oxide layer on the Al foil as well as the dicing of the pellets into legs are identified as the main origins of this behavior. In order to avoid any oxidation of the foil, a thin layer of Zn is sputtered after etching the Al surface; this method proves itself effective in keeping the contact resistivities of both interfaces equally low (<10 µΩ·cm2) after dicing. A slight gradient is observed in the n-type leg’s Seebeck coefficient after the contacting with the Zn-coated electrode and the role of Zn in this change is confirmed by comparing the experimental results to hybrid-density functional calculations of Zn point defects.

show abstract

“…As the n-type material, we used Mg 2 Si 0.3 Sn 0.675 Bi 0.025 , with the synthesis route and the thermoelectric properties given elsewhere. 41 In an attempt to compensate for the relatively large mismatch in CTE between MGS and HMS, here we used a ductile Pb-based soldering paste, instead of more commonly employed and more high-temperature-resistant thin layer of silver paint. 42 The metallization scheme employed here must be considered as an initial, easily implemented method.…”

Section: Module Characterizationmentioning

confidence: 99%

Fabrication of a Silicide Thermoelectric Module Employing Fractional Factorial Design Principles

Graff

Schuler

Song

et al. 2021

Journal of Elec Materi

Self Cite

View full text Add to dashboard Cite

Thermoelectric modules can be used in waste heat harvesting, sensing, and cooling applications. Here, we report on the fabrication and performance of a four-leg module based on abundant silicide materials. While previously optimized Mg2Si0.3Sn0.675Bi0.025 is used as the n-type leg, we employ a fractional factorial design based on the Taguchi methods mapping out a four-dimensional parameter space among Mnx-εMoεSi1.75−δGeδ higher manganese silicide compositions for the p-type material. The module is assembled using a scalable fabrication process, using a Cu metallization layer and a Pb-based soldering paste. The maximum power output density of 53 μW cm–2 is achieved at a hot-side temperature of 250 °C and a temperature difference of 100 °C. This low thermoelectric output is related to the high contact resistance between the thermoelectric materials and the metallic contacts, underlining the importance of improved metallization schemes for thermoelectric module assembly.

show abstract

High efficiency Mg₂(Si,Sn)-based thermoelectric materials: scale-up synthesis, functional homogeneity, and thermal stability

Abstract: Considering the need for large quantities of high efficiency thermoelectric materials for industrial applications, a scalable synthesis method for high performance magnesium silicide based materials is proposed.

Cited by 33 publications

References 69 publications

Developing Contacting Solutions for Mg₂Si_1–xSn_x-Based Thermoelectric Generators: Cu and Ni₄₅Cu₅₅ as Potential Contacting Electrodes

Developing Contacting Solutions for Mg₂Si_1–xSn_x-Based Thermoelectric Generators: Cu and Ni₄₅Cu₅₅ as Potential Contacting Electrodes

Overcoming Asymmetric Contact Resistances in Al-Contacted Mg2(Si,Sn) Thermoelectric Legs

Fabrication of a Silicide Thermoelectric Module Employing Fractional Factorial Design Principles

Contact Info

Product

Resources

About

High efficiency Mg2(Si,Sn)-based thermoelectric materials: scale-up synthesis, functional homogeneity, and thermal stability

Abstract: Considering the need for large quantities of high efficiency thermoelectric materials for industrial applications, a scalable synthesis method for high performance magnesium silicide based materials is proposed.

Cited by 33 publications

References 69 publications

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

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

Overcoming Asymmetric Contact Resistances in Al-Contacted Mg2(Si,Sn) Thermoelectric Legs

Fabrication of a Silicide Thermoelectric Module Employing Fractional Factorial Design Principles

Contact Info

Product

Resources

About

High efficiency Mg₂(Si,Sn)-based thermoelectric materials: scale-up synthesis, functional homogeneity, and thermal stability

Developing Contacting Solutions for Mg₂Si_1–xSn_x-Based Thermoelectric Generators: Cu and Ni₄₅Cu₅₅ as Potential Contacting Electrodes

Developing Contacting Solutions for Mg₂Si_1–xSn_x-Based Thermoelectric Generators: Cu and Ni₄₅Cu₅₅ as Potential Contacting Electrodes