[24a-E205-1~11] 9.4 Thermoelectric conversion

▼ [24a-E205-1] Crystal Structures and Thermoelectric Properties of Li-doped Mg₂Sn Single Crystals

〇(D)Zhicheng Huang¹, Kei Hayashi¹, Yuzuru Miyazaki¹ (1.Tohoku Univ.)

Keywords:Mg2Sn

Mg₂Sn is a promising mid-temperature thermoelectric (TE) material consisting of earth-abundant, low cost, and less-toxic elements. In this work, a series of Mg_2-xLi_xSn (x = 0, 0.005, 0.01, 0.02, 0.03) SCs with V_Mg were prepared by the melting method, whose morphology and TE properties were investigated with a particular emphasis on the effects of doped Li atoms and V_Mg. With Li content x increased, σ increased over the whole temperature range. The electrical conductivity of the x = 0.02 SC was higher than that of the Ga-doped SC ^[5] and was similar with that of the Li-doped Mg₂Sn SC ^[4]. Significantly, the Seebeck coefficient of the x = 0.02 SC was higher than that of the Li-doped Mg₂Sn PC ^[4]. We assumed that this behavior was affected by a larger carrier effective mass (m^*). As a result, the PF (~ 2 mW·m^-1·K^-2 for x = 0.02 SC) was higher than that of the Li-doped PC ^[4]. In addition, the κ was lower than that of the Li-doped PC ^[4] due to the enhanced phonon scattering by the introduced V_Mg. Finally, the zT_max value of 0.36 was achieved for Mg_1.98Li_0.02Sn at 600-650 K, which was 20% higher than that of the reference^[4].