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A2: Medium temperature materials

Synthesis and thermoelectric study of new ternary type-I Clathrate K8Al8Si38

Shiva Kumar Singh, M. Imai
National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki, 305-0047, Japan

Solid state devices based on thermoelectric materials, not only offer a solution to meet the increasing global demand of energy but also provide a pollution free environment. However, the present challenge is that most of the good thermoelectric materials discovered so far, either have toxic elements or have expensive and rare earth elements making it less reliable for commercial acceptance. We report here synthesis of new ternary clathrate compound K8Al8Si38 using elements which are non-toxic and abundant in earth crust. Rietveld refinement of X-Ray diffraction (XRD) pattern is carried out in order to check the phase formation and purity. The compound is crystallized in P m -3 n cubic space group with lattice parameter a = 10.45 (3) Å. Electron probe micro analysis (EPMA) confirms the formation of the sample in desired composition. Low temperature transport measurements suggest that semi-metallic/heavily doped semiconducting nature of the compound. The Seebeck coefficient is found to be 75 µV/K at 390 K.

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