Hybrid composite approach enhancing the thermoelectric performance of p-type iron-silicide synthesized by the arc melting-spark plasma sintering technique

Abstract

Iron-silicide (β-FeSi₂) is one of the most suitable and compatible thermoelectric compounds in applications of mid-temperature thermoelectric energy conversion technologies. Iron-silicide has the added advantages of low cost, non-toxicity, and thermal stability. Apart from these merits, their low figure of merit makes them inferior to others. We experimented with the SiGe particles incorporation into the β-FeSi₂ matrix to address these issues. The varying weight percentage of SiGe particle addition in FeSi₂ was made using the SPS compaction technique. Adding SiGe particles in Al-doped β-FeSi₂ resulted in a lower thermal conductivity than pristine compounds. Also, adding 12 wt% SiGe leads to a 34 % reduction in thermal conductivity values, primarily due to increased phonon scattering mechanisms. Moreover, the Seebeck coefficient exhibits notable improvements, resulting in an excellent thermoelectric performance of the p-type β-FeSi₂ compound. The figure-of-merit (zT) value of 0.19 was achieved in β-FeSi_1.9Al_0.1–12 wt % SiGe composite, a 57 % increase, compared to pristine β-FeSi_1.9Al_0.1 compounds.