Unraveling the Structural and Thermoelectric Properties of the Sn-Doped Filled Skutterudite Sm (Fe Ni1-)Sb11.5Sn0.5 (y = 0.17–0.34, x = 0.43–0.64)

A systematic study of the filled skutterudite system Smy(FexNi1-x)4Sb11.5Sn0.5 was carried out with the aim of investigating the effect of the partial substitution of Sb by Sn on the structural and thermoelectric properties of the material. The presence of Sn induces a shift of the p/n crossover toward lower values of x compared to the corresponding Sn-free system, as a consequence of the smaller number of electrons supplied. Moreover, a discontinuity at the p/n crossover is observed in the cell parameter and related structural features. The thermoelectric properties suggest lower thermal conductivity values in comparison to similar Sn-free skutterudite systems, resulting in higher ZT. This result highlights the significant role of Sn in creating new scattering centers able to affect the phonon transmission through the crystal lattice.