Authors: JiWei Liu Minghui Song Masaki Takeguchi Naohito Tsujii Yukihiro Isoda
Publish Date: 2014/10/01
Volume: 44, Issue: 1, Pages: 407-413
Abstract
A Mg2Si05Sn05 solid solution was prepared by mixing Mg2Si and Mg2Sn powders and hotpressing the mixture The Mg2Si05Sn05 samples exhibited a much lower thermal conductivity 192 W m−1 K−1 at 300 K than the parent Mg2Si 875 W m−1 K−1 and Mg2Sn compounds 628 W m−1 K−1 Xray diffraction measurements confirmed the successful synthesis of the Mg2Si05Sn05 solid solution Electron microscopy observations revealed that the grains were mainly 10–20 μm in size and had clean grain boundaries without obvious inclusions and precipitates The major phase was cubic Mg2Si05Sn05 MgO nanoparticles 10–20 nm in diameter were evenly dispersed in the Mg2Si05Sn05 matrix which probably reduced its thermal conductivity moreover uneven structures containing pure Si and Sn particles were found in the Mg2Si05Sn05 grains The origin and the formation mechanisms of the MgO and other impurity particles and their effect on thermoelectric properties of Mg2Si05Sn05 are discussed The low thermal conductivity of Mg2Si05Sn05 resulted in a relatively high dimensionless figure of merit ZT = 00132 at 300 K which may be further increased by optimizing the synthesis procedure alloy composition and doping level This work provides information on the structure and chemistry and their relationship with the thermoelectric properties of the Mg2Si05Sn05 solid solution it may help in developing other Mg2Si1−x Sn x compounds with superior thermoelectric properties
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