Thermoelectric properties of GeTe-CuInTe$_{2}$ alloys

GeTe-AgSbTe$_{2}$ and PbTe-AgSbTe$_{2}$ alloys, known as TAGS and LAST respectively, are excellent thermoelectric materials. By alloying the matrix with other ternary compounds, the thermal conductivity is significantly reduced due to the enhancement of phonon scattering by the formation of nano-sized secondary phases and disturbance to the lattice. Meanwhile, since the ternary compound AgSbTe$_{2}$ also exhibits good thermoelectric properties and Ag$^{+}$ and Sb$^{3+}$ tend to replace two Ge atoms at the same time, the mobility, and thus the power factor, will not be influenced much by this alloying. In this work, we replaced the ternary compound AgSbTe$_{2}$ by CuInTe$_{2}$ which does not contain the expensive element Ag and also exhibits good thermoelectric properties. We measured the Seebeck coefficient, electrical conductivity, thermal conductivity and Hall coefficient, and observed that CuInTe$_{2}$ almost has no influence on the power factor but does reduce the thermal conductivity. ZT was observed to improve to 1.2 at 800K for (Ge$_{2}$Te$_{2})_{0.97}$(CuInTe$_{2})_{0.03}$. We believe that ZT will be further enhanced at larger CuInTe$_{2}$ fractions due to further reduced thermal conductivity.