[19p-E307-1~15] 9.4 熱電変換

▼ [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.)

キーワード：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.