Thermoelectric properties of granular Mg3Sb2 particles

Abstract

This article presents the results obtained in the study of thermoelectric properties of granulated Mg3Sb2 particles. The results of the study show that the thermoelectric properties of granulated Mg3Sb2 particles mainly depend on the physical processes occurring in the interparticle boundary areas. As the temperature increases, the localized traps in the interparticle boundary areas are ionized, and the capture of charge carriers in them leads to a decrease in electrical conductivity (σ). The Seebeck coefficient (α) increases as the temperature difference occurs due to the potential difference and phonon absorption. Also, impurity thermal-voltaic effects appear with the formation of electron-hole pairs in impurity states with an energy level of Ein in the interparticle boundary regions. As a result, the total λ increases at the same time as the thermal conductivity of the two adjacent areas. The convergence of electrical conductivity and potential difference leads to a relatively stable change of λ. These processes lead to a change in the ZT index from ~0.021 to ~1.3 at T=300-700 K.