Thermoelectric properties of the doped Kondo insulator: ${\mathrm{Nd}}_x{\mathrm{Ce}}_{3-x}{\mathrm{Pt}}_3{\mathrm{Sb}}_4$

The temperature dependence of the thermopower, electrical resistivity, and thermal conductivity were explored for the solid solution ${\mathrm{Nd}}_x{\mathrm{Ce}}_{3-x}{\mathrm{Pt}}_3{\mathrm{Sb}}_4$ obtained from the parent Kondo insulator ${\mathrm{Ce}}_3{\mathrm{Pt}}_3{\mathrm{Sb}}_4.$ While ${\mathrm{Ce}}_3{\mathrm{Pt}}_3{\mathrm{Sb}}_4$ is a semiconductor with a small activation energy ${(E}_a\approx 0.05\pm 0.01\mathrm{eV})$ and a relatively large thermopower ($S=112\mathrm{}\pm 4\mu \mathrm{V}/\mathrm{K}$ at 300 K), ${\mathrm{Nd}}_3{\mathrm{Pt}}_3{\mathrm{Sb}}_4$ is a simple metal with a typically low thermopower $(S=8\mathrm{}\pm 1\mu \mathrm{V}/\mathrm{K}$ at 300 K). The thermoelectric figure of merit ZT of the ${\mathrm{Nd}}_x{\mathrm{Ce}}_{3-x}{\mathrm{Pt}}_3{\mathrm{Sb}}_4$ solid solution was found to be maximized at $x=0.35\mathrm{}\pm \mathrm{0.10.}$ The maximum ZT of 0.12 at approximately 230 K, however, is too small to be useful in thermoelectric applications.