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 ≈ 0.32 was found for the specimen Mg3.8Sb1.994Sn0.006 at 873 K, showing an improved ZT value compared to intrinsic one. Transport properties were also evaluated and discussed.

Abstract
1. Introduction
2. Materials and Methods
3. Results and Discussion
4. Conclusions
Acknowledgments
References

• Md. Mahmudur Rahman(Dept. of Material Sci. and Eng., Research Center for Sustainable Eco-Devices and Materials (ReSEM), Korea National University of Transportation, Chungju, Chungbuk, Republic of Korea)
• Il-Ho Kim(Dept. of Material Sci. and Eng., Research Center for Sustainable Eco-Devices and Materials (ReSEM), Korea National University of Transportation, Chungju, Chungbuk, Republic of Korea)
• Soon-Chul Ur(Dept. of Material Sci. and Eng., Research Center for Sustainable Eco-Devices and Materials (ReSEM), Korea National University of Transportation, Chungju, Chungbuk, Republic of Korea) Corresponding author