High figure of merit in partially filled ytterbium skutterudite materials

Abstract

We present evidence of a relatively high dimensionless figure of merit (ZT) in a polycrystalline skutterudite partially filled with ytterbium ions. The small-diameter yet heavy-mass Yb atoms partially filling the voids of the host ${\mathrm{CoSb}}_{\mathrm{3}}$ system exhibit low values of thermal conductivity while the quite favorable electronic properties are not substantially perturbed by the addition of Yb. This combination is ideal for thermoelectric applications exemplifying the “phonon-glass electron-crystal” concept of a thermoelectric material, resulting in $\mathrm{ZT}\text{=0.3}$ at room temperature and $\mathrm{ZT}\text{∼1}$ at 600 K for ${\mathrm{Yb}}_{\mathrm{0.19}}{\mathrm{Co}}_{\mathrm{4}}{\mathrm{Sb}}_{\mathrm{12}}.$