Effect of nickel substitution on thermoelectric properties of SryCo4Sb12

Bulk samples of Sr_yCo₄Sb₁₂ 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 Sr_0.26Co_3.95Ni_0.05 Sb₁₂