Xueying Zhao

Effect of Ge Doping on Thermoelectric Properties of SryCo4Sb12-xGex

Skutterudite compounds, SryCo4Sb12-xGex (y=0.3, x=0–0.3), are synthesized by a melting method. The effect of germanium doping on thermoelectric properties is investigated. Electrical conductivity, Seebeck coefficient, and thermal conductivity are measured from 300 to 850 K. The substitution of germanium is effective in reducing thermal conductivity while keeping excellent electrical transport properties owing to the high filling fraction of Sr and Ge doping as charge compensation. The dimensionless thermoelectric figure of merit ZT is observed to increase from 0.9 at 850 K for Sr0.28Co4Sb12 to 1.05 for Sr0.34Co4Sb11.9Ge0.1 at 850 K. These results suggest that doping with germanium is an attractive avenue to optimization of filled skutterudites.

Effect of nickel substitution on thermoelectric properties of SryCo4Sb12

Bulk samples of SryCo4Sb12 compounds were prepared by melting, quenching, annealing and spark plasma sintering, and characterized by X-ray diffraction and electron probe microanalysis. No impurity phases appear, and the lattice coefficient increases a little due to nickel substitution. The filling fraction of the compounds is smaller than that of the non-substituted ones. The temperature dependences of electrical conductivity, Seebeck coefficient and thermal conductivity were measured from room temperature to 850 K. The results show that nickel doping improves carrier concentration and electrical conductivity, does not change significantly the Seebeck coefficient due to the introduction of ion impurity carrier scattering, and further depresses the thermal conductivity of the strontium filled CoSb3 compounds. A maximum ZT value of 1.07 is achieved at 850 K for Sr0.26Co3.95Ni0.05 Sb12