Effect of Sn Doping on the Thermoelectric Properties of P-Type Mg3Sb2 Synthesized by Controlled Melting, Pulverizing Followed by Vacuum Hot Pressing

Zintl phase Mg3Sb2 is a promising thermoelectric material in medium to high temperature range due to its low band gap energy and characteristic electron-crystal phonon-glass behavior. P-type Mg3Sb2 has conventionally exhibited lower thermoelectric properties compared to its n-type counterparts, which have poor electrical conductivity. To address these problems, a small amount of Sn doping was considered in this alloy system. P-type Mg3Sb2 was synthesized by controlled melting, pulverizing, and subsequent vacuum hot pressing (VHP) method. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to investigate phases and microstructure development during the process. Single phase Mg3Sb2 was successfully formed when 16 at.% of Mg was excessively added to the system. Nominal compositions of Mg3.8Sb2-xSnx (0 <= x <= 0.008) were considered in this study. Thermoelectric properties were evaluated in terms of Seebeck coefficient, electrical conductivity, and thermal conductivity. A peak ZT value approximate to 0.32 was found for the specimen Mg3.8Sb1.994 Sn(0.006 )at 873 K, showing an improved ZT value compared to intrinsic one. Transport properties were also evaluated and discussed.

Automated summary

This study investigates the improvement of thermoelectric properties of Zintl phase magnesium antimonide (Mg3Sb2) by tin doping. P-type Mg3Sb2 was synthesized and its thermoelectric properties were evaluated along with the transport properties.