Effects of Ge substitution on thermoelectric properties of CrSi₂

Polycrystalline Cr(Si_1-xGe_x)₂ samples were prepared using arc melting and spark plasma sintering methods. Single-phase Cr(Si_1-xGe_x)₂ samples were obtained for the compositional range of 0 ≤ × ≤ 0.015 and the lattice parameters monotonically increased with x. In the range of single phases, the electrical conductivity and Seebeck coefficient increased and decreased with increasing x, respectively. The partial substitution of Ge effectively reduced the thermal conductivity to ∼80%, which resulted in the increase in the ZT of Cr(Si_1-xGe_x)₂ samples from 0.16 (x = 0) to 0.25 (x = 0.015) at 600 K. From the results of first-principles calculation for transport properties, it can be concluded that the origin of the increase in electrical conductivity and the decrease in Seebeck coefficient of Ge-substituted samples is the decrease in carrier effective mass.