Improved Thermoelectric Performance of Higher Manganese Silicides with Ge Additions
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Polycrystalline higher manganese silicides (HMS) with Ge additions were prepared by induction melting followed by hot-pressing. The phase structures and microstructure of the pellets were investigated, and their thermoelectric properties were measured from room temperature to 650°C. It was found that the solubility of Ge in HMS was limited to around 1.6%, beyond which an extra phase of Si y Ge1−y appeared. The electrical conductivity was continuously enhanced by Ge additions, while the Seebeck coefficient was slightly decreased. The thermal conductivity showed first a decreasing then an increasing relationship with increasing Ge additions. The HMS cells, mainly along the c-axis, were remarkably enlarged by the substitution of Ge, which probably resulted in the enhancement of phonon scattering due to an increased number of defects, reducing the phonon thermal conductivity. The dimensionless figure of merit of the optimized HMS polycrystals was improved by more than 30% compared with the pure HMS material.
KeywordsHigher manganese silicides Ge additions thermoelectric properties hot-pressing
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- 1.V.E. Borisenko, ed., Semiconducting Silicides (Berlin: Springer, 2000).Google Scholar
- 4.M.I. Fedorov and V.K. Zaitsev, Thermoelectrics Handbook, ed. D.M. Rowe (New York: CRC, 2005), p. 31.Google Scholar
- 17.O.G. Karpinskii and B.A. Evseev, Izv. Akad. Nauk SSSR, Neorg. Materialy. 5, 525 (1969).Google Scholar
- 21.E.N. Nikitin, A.F. Sidorov, V.I. Tarasov, and A.I. Zaslavskii, Izv. Akad. Nauk SSSR, Neorg. Materialy 6, 604 (1970).Google Scholar