Analyzing thermoelectric transport in n-type Mg2Si0.4Sn0.6 and correlation with microstructural effects: An insight on the role of Mg

Sankhla, Aryan; Kamila, Hasbuna; Kelm, Klemens; Mueller, E.; Boor, Johannes de

doi:10.1016/j.actamat.2020.07.045

Cited by 23 publications

(13 citation statements)

References 44 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Nevertheless, a far more important point to ensure long-term TEG performance is the material stability. It has been already shown that the n-type TE properties are very sensitive to Mg evaporation, which greatly alters the carrier concentration [27,30,[55][56][57]. The investigation of suitable coating and annealing conditions should therefore be prioritized for further TEG development, see, e.g., Refs.…”

Section: Discussionmentioning

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

Section: Discussionmentioning

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

show abstract

“…This could be due to grain boundary scattering having an impact at low temperatures. This has been observed for Mg 2 Si [60] and Mg 2 (Si,Sn) [61,62] as well as for other material classes [63,64]. The extent of grain boundary scattering apparently depends sensitively on the synthesis route and the synthesis parameters.…”

Section: Discussionmentioning

confidence: 74%

Developing a two-parabolic band model for thermoelectric transport modelling using Mg₂Sn as an example

2022

Self Cite

View full text Add to dashboard Cite

Thermoelectrics is a field driven by material research aimed at increasing the thermal to electrical conversion efficiency of thermoelectric (TE) materials. Material optimisation is necessary to achieve a high figure of merit (zT) and in turn a high conversion efficiency. Experimental efforts are guided by the theoretical predictions of the optimum carrier concentration for which generally the Single Parabolic Band (SPB) model is used which considers the contribution to electronic transport only from the majority carriers’ band. However, most TE materials reach peak performance (maximum zT) close to their maximum application temperature and when minority carrier effects become relevant. Therefore, single band modelling is insufficient to model the behaviour of TE materials in their most practically relevant temperature range. Inclusion of minority effects requires addition of the minority carrier band and necessitates the use of a two-band model – the simplest and, for most cases, sufficient improvement. In this study, we present a systematic methodology for developing a two-band model using one valence and one conduction band for any TE material. The method utilises the SPB model and a simple cost function-based analysis to extract material parameters like density of states masses, band gap, deformation potential constant etc., based on easily available experimental data. This simple and powerful method is exemplified using Mg2Sn (an end member of the highly popular Mg2(Si,Sn) solid solutions), chosen due to its low band gap and the availability of experimental data in a wide range of dopant concentrations. Using the experimental data for p- and n-type Mg2Sn from literature, a two-band model was obtained and optimum carrier concentration and maximum zT were predicted. At 650 K, pronounced differences between the SPB and the two-band model, which could prevent realisation of maximum zT, were observed demonstrating the practical necessity to model the effect of minority carriers.

show abstract

“…observed for Mg 3 Sb 2 and Mg 2 Si systems, where going from Mg-rich to Mg-poor can change the carrier concentration by $10 20 cm À3 and even switch polarity. 33,35,[51][52][53][54] This indicates that (at least with the employed synthesis approach) the carrier concentration range of single phase MgAg 0.97 Sb 0.995 is relatively narrow and the phase width is hence small or the compensation between different defect types is strong.…”

Section: Synthesis Process Optimization: Reproducible Resultsmentioning

confidence: 99%

Establishing synthesis–composition–property relationships for enhanced and reproducible thermoelectric properties of MgAgSb

et al. 2022

Self Cite

View full text Add to dashboard Cite

show abstract

Analyzing thermoelectric transport in n-type Mg2Si0.4Sn0.6 and correlation with microstructural effects: An insight on the role of Mg

Cited by 23 publications

References 44 publications

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

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

Developing a two-parabolic band model for thermoelectric transport modelling using Mg₂Sn as an example

Establishing synthesis–composition–property relationships for enhanced and reproducible thermoelectric properties of MgAgSb

Contact Info

Product

Resources

About

Analyzing thermoelectric transport in n-type Mg2Si0.4Sn0.6 and correlation with microstructural effects: An insight on the role of Mg

Cited by 23 publications

References 44 publications

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

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

Developing a two-parabolic band model for thermoelectric transport modelling using Mg2Sn as an example

Establishing synthesis–composition–property relationships for enhanced and reproducible thermoelectric properties of MgAgSb

Contact Info

Product

Resources

About

Developing a two-parabolic band model for thermoelectric transport modelling using Mg₂Sn as an example