Synthesis and thermoelectric properties of Sr-filled skutterudite SryCo4Sb12

Strontium-filled skutterudites SryCo4Sb12 have been synthesized by a melting method. The filling fraction of Sr in CoSb3 skutterudite is up to y=0.40, closely consistent with the calculated value by density functional theory methods. The lattice parameters increase linearly with the increase of Sr content, and the relative change in lattice parameters is in agreement with theoretical prediction. Hall effect measurements have been performed by Van de Pauw method at room temperature. All samples filled with Sr atom exhibit n-type conduction. The thermal and electrical transport properties have been measured in the temperature range of 300-850 K. The lattice thermal conductivity of SryCo4Sb12 is significantly depressed as compared to that of the unfilled CoSb3. The dimensionless thermoelectric figure of merit, ZT, increases with increasing temperature and reaches a maximum value of 0.9 for Sr0.28Co4Sb12 at 850 K.