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A3: High temperature materials

Thermoelectric Property of Tin Selenide Prepared by Spark Plasma Sintering and Iodine as a Potential N-type Dopant in SnSe

Bin He1, Bartek Wiendlocha1,2 and Joseph P. Heremans1,3
1 Department of Mechanical and Aerospace Engineering, the Ohio State University, Columbus, Ohio2 AGH University of Science and Technology, 30-059 Krakow, Poland3 Department of Physics, the Ohio State University, Columbus, Ohio

Tin selenide (SnSe) has an orthorhombic structure at room temperature. Unlike tin telluride (SnTe) which has a high intrinsic concentration, SnSe has nearly no intrinsic vacancies and a low intrinsic carrier concentration. Stoichiometric SnSe is prepared by melting-ball mill-SPS process. Thermoelectric properties of low temperature are measured in a cryostat down to 80K. High temperature Seebeck and resistivity were measures in a Linseis LSR3, and thermal diffisivity by a flash method (Anter) up to 873K. Samples are very resistive at room temperature with a Seebeck coefficient of about 500μV/K. At high temperature, the Seebeck coefficient drops to about 300μV/K while the resistivity is reduced by an order of magnitude. Varying the ratio of Sn and Se will slightly change the properties and the best power factor is about 3.5μW/cmK2 at 873K. The thermal conductivity is about 0.37W/mK respectively. Iodine is an n-type dopant in SnSe. At about 723K, I doped SnSe becomes n-type and the Seebeck coefficient of I doped SnSe at 773K will be reported. The best ZT (about 0.8) comes from the off-stoichiometric p-type samples. Experimental results are analyzed in correlation with electronic structure calculations, done using KKR-CPA method.