On the role of Mg content in Mg2(Si,Sn): Assessing its impact on electronic transport and estimating the phase width by in situ characterization and modelling

Sankhla, Aryan; Kamila, Hasbuna; Naithani, Harshita; Mueller, E.; Boor, Johannes de

doi:10.1016/j.mtphys.2021.100471

Cited by 13 publications

(12 citation statements)

References 45 publications

(53 reference statements)

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“…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

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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: 99%

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

et al. 2021

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“…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%

“…[27][28][29][30][31] This was found to be particularly true for Mg-based materials like Mg 2 (Si,Sn) and Mg 3 (Sb,Bi) 2 , where Mg-related intrinsic defects govern the carrier mobility and charge carrier concentration to an extent that this can be used to select the majority carrier type. [32][33][34][35] For MgAgSb, the main phase properties are likewise governed by intrinsic defects, e.g. Ag vacancies, Ag antisite defects on Mg sites, Sb vacancies [36][37][38] whose concentrations are linked to minimal changes in the composition.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2022

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“…The Mg element was chosen as the priority in the Cu-based TEiM to create an Mg overcompensation environment to enhance stability, considering the susceptibility to Mg deficiency in Mg 2 (Si, Ge, Sn) TEcM. [22][23][24][25][26][27] While a suitable interdiffusion at the TEiM/TEcM interface is necessary for robust interface bonding, [9] if the diffusion is too abrupt, it would result in instability during the service. Given the instability exhibited by the Cu/Mg 2 Sn 0.75 Ge 0.25 interface at elevated temperatures, an element with appreciative diffusion was required, which was also less reactive with Mg 2 (Si, Sn)-based TEcM.…”

Section: Design Of the Teimmentioning

confidence: 99%

Interface Engineering Boosting High Power Density and Conversion Efficiency in Mg₂Sn_0.75Ge_0.25‐Based Thermoelectric Devices

Lin

Liu

et al. 2023

Advanced Energy Materials

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Electrode contact interfaces for practical thermoelectric (TE) devices require high bonding strength, low specific contact resistivity, and superb stability. Herein, the state‐of‐the‐art Cu2MgFe/Mg2Sn0.75Ge0.25 interface is designed for Mg2Sn0.75Ge0.25‐based TE devices, adhering to the general strategy of high bonding propensity, thermal expansion matching, diffusion passivation, and dopant inactivation. The interfacial stability is verified by the in situ transmission electron microscopy analysis, thereby confirming the contributions from decreasing the chemical potential gradient and increasing the diffusion activation energy barrier. The single‐leg device exhibits a high power density (ωmax) of 2.6 W cm−2 and conversion efficiency (ηmax) of 8% under a temperature difference (ΔT) of 370 °C, which is the record‐breaking value in comparison to other Mg2(Si, Ge, Sn)‐based TE devices. Additionally, a two‐couple device with p‐type Bi2Te3 shows an excellent ωmax of 1.3 W cm−2 and ηmax of 5.4% under a ΔT of 270 °C, comparable to commercial Bi2Te3 devices. The proposed interface design strategy provides a general technique for constructing high‐performance devices using cutting‐edge TE materials.

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On the role of Mg content in Mg2(Si,Sn): Assessing its impact on electronic transport and estimating the phase width by in situ characterization and modelling

Cited by 13 publications

References 45 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

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

Interface Engineering Boosting High Power Density and Conversion Efficiency in Mg₂Sn_0.75Ge_0.25‐Based Thermoelectric Devices

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On the role of Mg content in Mg2(Si,Sn): Assessing its impact on electronic transport and estimating the phase width by in situ characterization and modelling

Cited by 13 publications

References 45 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

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

Interface Engineering Boosting High Power Density and Conversion Efficiency in Mg2Sn0.75Ge0.25‐Based Thermoelectric Devices

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Interface Engineering Boosting High Power Density and Conversion Efficiency in Mg₂Sn_0.75Ge_0.25‐Based Thermoelectric Devices