Enhanced thermoelectric properties of CoSb₃-based skutterudites by filling Se as electronegative element

Filling electronegative guests into CoSb₃-based skutterudites has been regarded as a promising way to improve their electrical and thermal transport properties. In this study, a series of Se_yCo_4-xPd_xSb_12-2ySe_2y compounds have been prepared by traditional solid state reaction methods. Se as electronegative element was introduced into both the voids and the Sb sites of CoSb₃-based skutterudite, and Pd was further introduced to stabilize Se in the voids. The phase compositions and electrical and thermal transport properties of the compounds have been investigated and the related mechanisms were explored. It is found that the forming of thermodynamically stable compounds is due to the charge compensation between the Pd and Se. By balancing the effect of the decrease of κ _L and the decrease of σ, the zT of Se_0.2Co_3.7Pd_0.3Sb_11.6Se_0.4 sample amounted up to 0.88. With Te introduced into Se_0.2Co_3.7Pd_0.3Sb_11.6Se_0.4 sample, the filling fraction of Se indeed increase by the charge-compensation effect of Pd and Te. And the zT of Se_0.2Co_3.7Pd_0.3Te_0.2Sb_11.4Se_0.4 sample was further improved to about 0.9. (paper)