Co-doping of Al and Bi to control the transport properties for improving thermoelectric performance of Mg2Si

Kim, Gwansik; Kim, Jeongmin; Lee, Hwijong; Cho, Sungmee; Lyo, Inwoong; Noh, Sujung; Kim, Byung‐Wook; Kim, Sung Wng; Lee, Kyu Hyoung; Lee, Wooyoung

doi:10.1016/j.scriptamat.2016.01.027

Cited by 21 publications

(10 citation statements)

References 25 publications

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“…The case of Al diffusion into n-type Mg 2 (Si,Sn) was already discussed in a previous work, where no gradient was found after contacting with non-coated Al foils [30], similarly to the first results in this work (see line scans in SI). It also appears that Al is a poor dopant for this material system as shown in [49][50][51][52][53]. It is, therefore, unlikely that the diffusion of Al into the n-type TE material is at the origin of the change in carrier concentration.…”

Section: Discussionmentioning

confidence: 92%

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

et al. 2021

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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.

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Section: Discussionmentioning

confidence: 92%

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

et al. 2021

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“…Mg 2 Si-based compounds have further advantages for ATEGs such as non-toxicity, low density, and low cost. Hence, several investigations have focused on the improvement in the ZT of Mg 2 Si by doping the Si-sites (with Bi or Sb) and Mg-sites (with Al), using Mg 2 Sn and Mg 2 Ge solid solutions, and introducing nanophases [1][2][3][4][5][6][7]. As a result, the maximum ZT of the Mg 2 Si was determined to be ~ 1.2 at 770 K on a lab scale [8].…”

Section: Introductionmentioning

confidence: 99%

Intercorrelated Relationship Between the Thermoelectric Performance and Mechanical Reliability of Mg2Si-Reduced Graphene Oxide Nanocomposites

Kim

Lee

2020

Electron. Mater. Lett.

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We fabricated Mg 2 Si-based thermoelectric nanocomposites with reduced graphene oxide using ultrasonic-based wet chemical pulverizing-mixing and spark plasma sintering to improve the trade-off relationship between thermoelectric properties and mechanical reliability. The dependence of thermoelectric properties and mechanical reliability on the nanophase morphologies has been systemically investigated, demonstrating the fracture toughness of the nanocomposite with thin reduced graphene oxide significantly increased. Moreover, the introduction of the few-layered reduced graphene oxide with high interface density was more effective in improving the trade-off relationship. This result suggests that an in-depth research on the dependence of the thermoelectric properties and mechanical reliability on the intrinsic properties of the nanophases is required to prepare efficient thermoelectric nanocomposites.

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“…Several doping elements have been examined for increasing the figure of merit of Mg 2 Si. Bismuth, for instance, can increase the electrical conductivity and reduce thermal conductivity of Mg 2 Si. − It has been shown that aluminum can increase the solubility of bismuth in silicon sites of Mg 2 Si , and increase the figure of merit of magnesium silicide to 0.9 at 900 K. However, the doping efficiency is reduced by the formation of Bi 2 Mg 3 due to a magnesium excess, which is typically added to compensate for magnesium evaporation when the synthesis and/or sintering temperature is above 900 K . By suppressing magnesium evaporation, extra magnesium would no longer be needed.…”

Section: Introductionmentioning

confidence: 99%

Activated Reactive Consolidation Method as a New Approach to Enhanced Thermoelectric Properties of n-Type Nanostructured Mg₂Si

Alinejad

Takagiwa

Ikeda

2020

ACS Appl. Energy Mater.

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The activated reactive consolidation method was implemented to enhance the thermoelectric properties of n-type Mg2Si binary components. This method consists of the preparation of a nanocomposite of highly activated starting materials using silicon nanoparticles. These particles were embedded in magnesium forming a so-called “plum-pudding microstructure”. This gives rise to a magnesium–silicon interface, which facilitates diffusion in a short time and at a lower temperature during hot consolidation. Bi–Al co-doped Mg2Si was prepared by this method and a single phase was achieved. The highest zT value of about 1.05 was achieved at 850 K with a high power factor of 3.6 × 10–3 Wm–1 K–2. The enhanced power factor is attributed to suppression of MgO and Bi2Mg3 formation and the significant increase in the electrical conductivity. Approximately 2 h of planetary ball-milling and 10 min of hot pressing at 600 °C are all of the required processes to fabricate the samples in this study. These synthesis conditions lead to the most rapid and simple process for preparing Mg2Si thermoelectric materials.

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Co-doping of Al and Bi to control the transport properties for improving thermoelectric performance of Mg2Si

Cited by 21 publications

References 25 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

Intercorrelated Relationship Between the Thermoelectric Performance and Mechanical Reliability of Mg2Si-Reduced Graphene Oxide Nanocomposites

Activated Reactive Consolidation Method as a New Approach to Enhanced Thermoelectric Properties of n-Type Nanostructured Mg₂Si

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Co-doping of Al and Bi to control the transport properties for improving thermoelectric performance of Mg2Si

Cited by 21 publications

References 25 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

Intercorrelated Relationship Between the Thermoelectric Performance and Mechanical Reliability of Mg2Si-Reduced Graphene Oxide Nanocomposites

Activated Reactive Consolidation Method as a New Approach to Enhanced Thermoelectric Properties of n-Type Nanostructured Mg2Si

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Product

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Activated Reactive Consolidation Method as a New Approach to Enhanced Thermoelectric Properties of n-Type Nanostructured Mg₂Si