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A2: Medium temperature materials
CoSi is an inexpensive, non-polluting thermoelectric material for medium temperatures (200-700°C). Its power factor, similar to the state of the art materials, makes this silicide a promising candidate for the next generation of thermoelectrics. Nevertheless most of the works on non-doped CoSi report power factors inferior to the best one. This is probably due to its relatively wide domain of existence, between 49 and 51% of silicon.
Even though an excess or defect in silicon seems harmful for Seebeck and electrical conductivity, the effect of non-stoichiometry has never been studied systematically. In this work we investigate the domain of existence of CoSi at different temperatures. We also observe the effect of Si content on B20 CoSi thermoelectric performances, with particular attention to Seebeck coefficient and electrical conductivity. Theoretical calculations qualitatively confirm the effect of composition on defects concentration and how defects influences electronic properties.
