Synthesis and characterization of doped Mg2Si0.4Sn0.6 thermoelectric material made in exclusion of glove box

Abstract

The Mg2X (X = Si and Sn) based alloys which are composed of abundant, non-toxic and inexpensive elements are promising mid-temperature thermoelectric (TE) materials. Herein, we report the synthesis of Mg2Si0.4Sn0.6 through high energy ball milling followed by hot pressing for thermoelectric application, where handling of the elemental powders was processed in the ambient laboratory conditions in the exclusion of the glove box. Mg2Si0.4∼0.3Sn0.6∼0.7 shows conduction band convergence which is a favorable feature for enhancing the zT in the n-type TE material, and dopants Bi, Sb and Al have been used for imparting the n-type conduction. To get enhanced p-type performance, heavier compositions are feasible and the same parent composition has been used for Ag as a dopant to provide p-type conductivity. The samples have been investigated for confirmation of phases and elements, electrical and thermoelectric transport properties using X-Ray Diffractometer, Hall effect measuring equipment, Semiconductor Device Analyzer, ZEM, and Laser Flash Analyzer. The Ag-doped sample showed comparatively better electrical properties owing to an additional p-type conductivity rendered by the antisite defects of Mg on Si (MgSi). Further, its elemental and microstructural analysis were carried out by an X-ray Photoelectron Spectroscopy, Scanning Electron Microscope, and Transmission Electron Microscope, respectively.