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A2: Medium temperature materials

Microstructure of Mg2(Si0.4Sn0.6)1-xTix (0<x<0.07) thermoelectric materials through cold isostatic pressure (CIP)

M. B. A. Bashira, M. F. M. Sabria*, S. M. Saidb, D. A. Shnawaha and M. H Elsheikha
aDepartment of Mechanical Engineering, University of Malaya, 50603 KL, MalaysiabDepartment of Electrical Engineering, University of Malaya, 50603 KL, Malaysia

 Mg2Si0.4Sn0.6 has been identified as a promising thermoelectric material for application in the mid temperature range (500 – 900 K). It also has the advantage of abundance of raw material, low cost and low environmental impact. In this work; N-type Mg2(Si0.4Sn0.6)1-xTix (0 < x < 0.07) compounds have been successfully synthesized by solid-state reaction method combined with cold isostatic pressure (CIP) technique. The complex has been characterized by x-ray powder diffraction (XRD) and transmission electron microscopy (TEM). The result of XRD analysis confirmed that all sintered compacts contained the Mg2Si0.4Sn0.6 antifluorite structure phase. The sintered samples have been characterized by x-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM).  The additions of Ti doping are able to form Sn-rich precipitates with free electrons dispersed in the Mg2Si0.4Sn0.6 matrix. This in turn leads to enhance the electrical properties. Moreover, the formation of these Sn-rich phases also induce phonon scattering and reduce the thermal conductivity, and subsequently improve the figure of merit.