Synthesis of Mg sub(2)Si for thermoelectric applications using magnesium alloy and spark plasma sintering

Magnesium silicide was synthesized through a solid-state reaction at 400 degree C between chips of commercially pure Mg or AZ31 magnesium alloy and silicon fine powders. The use of alloy AZ31 allows Al to be introduced as a dopant. The synthesized silicide powders were consolidated by spark plasma s...

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Bibliographic Details
Published inJournal of alloys and compounds Vol. 589; pp. 485 - 490
Main Authors Hu, Xiaokai, Mayson, Dylan, Barnett, Matthew R
Format Journal Article
LanguageEnglish
Published 15.03.2014
Subjects
Alloys
Aluminum
Intermetallic compounds
Intermetallics
Magnesium
Magnesium base alloys
Magnesium compounds
Semiconductors
Silicides
Thermoelectricity
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Summary:Magnesium silicide was synthesized through a solid-state reaction at 400 degree C between chips of commercially pure Mg or AZ31 magnesium alloy and silicon fine powders. The use of alloy AZ31 allows Al to be introduced as a dopant. The synthesized silicide powders were consolidated by spark plasma sintering at 750 degree C. X-ray diffraction and scanning electron microscopy were used to confirm the phase purity and structural evolution from powder to bulk material. The crystalline grains in the Mg sub(2)Si bulk were identical to the raw Si powder in size. The Al impurity increased the electrical conductivity of Mg sub(2)Si while the Seebeck coefficient was lowered. The thermal conductivities were almost the same for Mg sub(2)Si and doped Mg sub(2)Si. The optimal thermoelectric figure of merit (ZT) was 0.58 at 844 K in the n-type Al-doped Mg sub(2)Si material. Inductively coupled plasma emission spectroscopy was employed to determine the concentration of Al dopant.
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ISSN:0925-8388
DOI:10.1016/j.jallcom.2013.11.092