No abstract

High cost, toxicity, and thermal instability issues curtail the usage of thermoelectric power generators (TEGs) for waste heat recovery applications. Mg2Si1–x Sn x based thermoelectric material is a proven low cost, nontoxic, and earth crust abundant material for mid-temperature device applications. Still, its thermal stability and mechanical properties remain challenging and unascertained. This work reports a facile and simple production of Mg2Si1–x Sn x material employing a composite approach using an in situ plasma-assisted reaction sintering process. The enhanced thermoelectric properties associated with a remarkable hardness value of ≃5.2 GPa and high fracture strength of ≃2.17 MPa√m were realized in plasma-assisted reactive sintered Mg2Si1–x Sn x material, using suitable doping and reinforcement additions. The synthesized composite material improves the mechanical robustness and superior thermoelectric performance, which is a prerequisite for ensuring the commercial viability of Mg2Si1–x Sn x based materials.

Contact electrodes and their adequate joining are the main bottlenecks in realizing low-cost Mg2(Si,Sn) thermoelectric materials for thermoelectric generator applications. The resistance and diffusion chemistry between the thermoelectric elements and contact electrodes play an essential role in achieving high-performance thermoelectric generators for intermediate-temperature applications. A facile single-step spark plasma sintering process was employed to fabricate Sb-doped Mg2Si0.9Sn0.1 and contact joining simultaneously. The single-step-processed thermoelectric element’s power output characteristics with three different contacts (Ni, MnSi, and FeSi2) were investigated by employing a thermoelectric conversion efficiency evaluation system. Our experimental strategy demonstrated that the single-step processing of Mg2(Si0.9Sn0.1)0.95Sb0.05/Ni joining imparts the lowest internal resistance and high-power output characteristics and eliminates the main obstacle of Mg2(Si,Sn) material integration in thermoelectric power generators.