[19p-E307-1~15] 9.4 Thermoelectric conversion

▼ [19p-E307-10] Improvement of thermoelectric properties of Ag₂S by Se substitution

〇(P)Saurabh Singh¹, Keisuke Hirata¹, Dogyun Byeon¹, Swapnil Ghodke¹, Masaharu Matsunami¹, Masahiro Adachi², Yoshiyuki Yamamoto², Tsunehiro Takeuchi¹ (1.Toyota Tech. Inst., 2.Sumitomo Elect. Ind.)

Keywords:Thermoelectric, Chalcogenides, inorganic thermoelectrics

In the past several decades, worldwide research have been extensively focused on thermoelectric (TE) materials for conversion of waste heat into useful electrical energy.¹ Among, various class of TE materials studied so far, chalcogenides materials, A₂X (where A = Ag, Cu and X = S, Se, Te) have attracted much attention due to low thermal conductivity (k) and semiconducting electronic structure. In the low temperature phase of this type of material, the lower k value make it more favorable to obtain large dimensionless figure-of-merit, ZT. In addition to lower value of k; the large value of Seebeck coefficient (S) and electrical conductivity (s) are required to get a larger value of power factor (PF = S²s). About room temperature, the lower value of k (~0.5 W/mK) and higher S (~ -900 mV/K) are very suitable for making the ZT value higher in Ag₂S. However, in the low temperature phase, Ag₂S shows very high electrical resistivity (~3.2×10⁷ mohm-cm at 300 K), whereas, the low temperature phase of Ag₂Se shows very low resistivity (~0.8 mohm-cm).^2,3 Therefore, an enhancement in the electrical conductivity of Ag₂S is required for its better thermoelectric properties. Thus, to improve the ZT, an investigation was carried out by Se substitution on sulphur site of Ag₂S_1-xSe_x.