High-throughput study of the structural stability and thermoelectric properties of transition metal silicides

The phase stability, electronic structure and transport properties of binary 3d, 4d and 5d transition metal silicides are investigated using high-throughput density functional calculations. An overall good agreement is found between the calculated 0 K phase diagrams and experiment. We introduce descriptors for the phase-stability and thermoelectric properties and hereby identify several candidates with potential for thermoelectric applications. This includes known thermoelectrics like Mn4Si7, β-FeSi2, Ru2Si3 and CrSi2 as well as new potentially meta-stable materials like Rh3Si5, Fe2Si3 and an orthorhombic CrSi2 phase. Analysis of the electronic structure shows that the gap formation in most of the semiconducting transition metal silicides can be understood with simple hybridization models. The transport properties of the Mn4Si7, Ru2Ge3 and Ir3Si5 structure types and the orthorhombic CrSi2 phase are discussed. The calculated transport properties are in good agreement with available experimental data. It is shown that a better thermoelectric performance may be achieved upon optimal doping. Finally, the high-throughput data are analysed and rationalized using a simple tight-binding model.