Process-structure-properties relationship in low-cost thermoelectric iron silicide synthesis

Abstract

A trade-off between thermoelectric performance and cost-effectiveness makes commercial thermoelectric power generation possible in green energy applications. In this direction, FeSi2 based thermoelectric material has excellent potential and possesses low-cost, earth abundance and non-toxic constituent elements; still, the thermoelectric performance of FeSi2 materials is inferior to other mid-temperature thermoelectric materials. Also, the fabrication methods and synthesis routes are complex and time-consuming processes, restricting their competitiveness in mid-temperature applications. This work reports a simple processing strategy for β-FeSi2 synthesis employing arc-melting and spark plasma sintering techniques. The improved thermoelectric performance and remarkable mechanical properties were realised using these techniques. A substantial improvement in the hardness value of ≃ 6.5 GPa and fracture toughness value of ≃ 3.18 MPa√m was achieved, mainly due to its microstructural features. The processing-structure-properties relationship was established to ensure FeSi2 based thermoelectric materials' commercial viability.