Thermoelectric properties of Sn substituted p-type Nd filled skutterudites

Highlights: • Sn-doped Nd_0.6Fe₂Co₂Sb₁₂p-type skutterudites were prepared. • Sn-doping for Sb increases the Nd filling fraction. • The in situ nanoinclusions were introduced by Sn-doping. • The thermal conductivity is intensively suppressed by 40% at room temperature. • ZT is significantly increased through Sn-doping. - Abstract: Nd_0.6Fe₂Co₂Sb_12−xSn_x (0 ⩽ x ⩽ 0.6 nominal) skutterudite compounds were synthesized by traditional heat treatment method. Sn substitution on Sb (24g) site was verified by X-ray powder diffraction, energy dispersive spectrometry, and Raman spectroscopy. It was determined that substituting Sb with Sn increases the Nd filling fraction. Along with the in situ nanoinclusions introduced by Sn, the thermoelectric behavior of Sn in Nd_0.6Fe₂Co₂Sb_12−xSn_x differs from those seen in CoSb₃. Despite the increase of electrical resistivity, the enhanced Seebeck coefficient and suppressed lattice thermal conductivity resulted in a 30% improvement of ZT for Nd_0.6Fe₂Co₂Sb_11.6Sn_0.4 compared with that of Sn-free sample. We hope our work can complement the knowledge of pnicogen-substituted p-type skutterudite family and demonstrate the ways to improve their properties through compositional modification as well as in situ formation of nanoinclusions