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Thermoelectric performance of n-type Mg2Ge

Journal Article


Abstract


  • Magnesium-based thermoelectric materials (Mg2X, X=Si, Ge, Sn) have received considerable attention

    due to their availability, low toxicity, and reasonably good thermoelectric performance. The synthesis

    of these materials with high purity is challenging, however, due to the reactive nature and high

    vapour pressure of magnesium. In the current study, high purity single phase n-type Mg2Ge has been

    fabricated through a one-step reaction of MgH2 and elemental Ge, using spark plasma sintering (SPS)

    to reduce the formation of magnesium oxides due to the liberation of hydrogen. We have found that

    Bi has a very limited solubility in Mg2Ge and results in the precipitation of Mg2Bi3. Bismuth doping

    increases the electrical conductivity of Mg2Ge up to its solubility limit, beyond which the variation is

    minimal. The main improvement in the thermoelectric performance is originated from the significant

    phonon scattering achieved by the Mg2Bi3 precipitates located mainly at grain boundaries. This reduces

    the lattice thermal conductivity by ~50% and increases the maximum zT for n-type Mg2Ge to 0.32,

    compared to previously reported maximum value of 0.2 for Sb-doped Mg2Ge.

Publication Date


  • 2017

Citation


  • Santos, R., Nancarrow, M., Dou, S. Xue. & Aminorroaya-Yamini, S. (2017). Thermoelectric performance of n-type Mg2Ge. Scientific Reports, 7 3988-1-3988-7.

Scopus Eid


  • 2-s2.0-85021149207

Ro Metadata Url


  • http://ro.uow.edu.au/aiimpapers/2586

Start Page


  • 3988-1

End Page


  • 3988-7

Volume


  • 7

Place Of Publication


  • United Kingdom

Abstract


  • Magnesium-based thermoelectric materials (Mg2X, X=Si, Ge, Sn) have received considerable attention

    due to their availability, low toxicity, and reasonably good thermoelectric performance. The synthesis

    of these materials with high purity is challenging, however, due to the reactive nature and high

    vapour pressure of magnesium. In the current study, high purity single phase n-type Mg2Ge has been

    fabricated through a one-step reaction of MgH2 and elemental Ge, using spark plasma sintering (SPS)

    to reduce the formation of magnesium oxides due to the liberation of hydrogen. We have found that

    Bi has a very limited solubility in Mg2Ge and results in the precipitation of Mg2Bi3. Bismuth doping

    increases the electrical conductivity of Mg2Ge up to its solubility limit, beyond which the variation is

    minimal. The main improvement in the thermoelectric performance is originated from the significant

    phonon scattering achieved by the Mg2Bi3 precipitates located mainly at grain boundaries. This reduces

    the lattice thermal conductivity by ~50% and increases the maximum zT for n-type Mg2Ge to 0.32,

    compared to previously reported maximum value of 0.2 for Sb-doped Mg2Ge.

Publication Date


  • 2017

Citation


  • Santos, R., Nancarrow, M., Dou, S. Xue. & Aminorroaya-Yamini, S. (2017). Thermoelectric performance of n-type Mg2Ge. Scientific Reports, 7 3988-1-3988-7.

Scopus Eid


  • 2-s2.0-85021149207

Ro Metadata Url


  • http://ro.uow.edu.au/aiimpapers/2586

Start Page


  • 3988-1

End Page


  • 3988-7

Volume


  • 7

Place Of Publication


  • United Kingdom