Enhanced thermoelectric performance of optimized Yb-filled and Fe-substituted skutterudite compounds Yb0.6FexCo4-xSb12

Optimized Yb-filled Fe-substituted skutterudites Yb0.6FexCo4-xSb12 (x = 0, 0.5, and 1.0) were synthesized using a high-pressure technique. The samples were characterized by powder X-ray diffraction (XRD) analysis and electron probe microanalysis (EPMA). The thermoelectric transport properties of the samples such as Seebeck coefficient, electrical conductivity, carrier concentration, and thermal conductivity were studied in the temperature range of 2-300 K. With 1/8 Fe substitution for the Co site (x = 0.5), the Seebeck coefficient and thermal conductivity were obviously optimized. Carrier concentration analysis indicates that proper Fe substitution can effectively compensate for the excess electrons and optimize the electric transport properties. The reduction in the total thermal conductivity. could be mainly caused by the reduction in electron contribution to kappa. Compared with an only-Yb-filled compound, a 26% improved figure of merit ZT was achieved at 300K at the Fe substitution ratio x = 0.5 (ZT = 0.11). This result confirms that Fe substitution on the Co site is an effective approach to tuning and optimizing the thermoelectric properties of CoSb3-based skutterudites. (C) 2016 The Japan Society of Applied Physics