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Thermoelectricity is a direct conversion between heat energy and electrical power, making it an attractive renewable energy source. Other advantages include that thermoelectric modules have no moving parts, which makes them well-suited to a variety of specialized applications (e.g., space exploration and cryogenic refrigeration). However, such materials also face limitations due to an intrinsic competition between their electronic and lattice behaviors. This is especially true for low-temperature thermoelectrics which, so far, have not been widely used in technologies. Intriguingly, it was recently shown that some of the compounds YbTM₂Zn₂₀ (TM = transition metal) exhibit competitive thermoelectric properties at low temperatures, that are likely related to strong hybridization between the f- and conduction electron states [1, 2]. Expanding on this, we investigate chemical substitution on the transition metal site of YbIr₂Zn₂₀ using nickel and platinum. Large single crystals were synthesized using the molten metal flux growth technique, where the structure was characterized using powder X-ray diffraction and the stoichiometry was determined using energy dispersive spectroscopy. Through magnetic, electrical, and thermal properties measurements, we will reveal changes in the electronic and structural states, and their influence on the thermoelectric properties.

[1] Mun, et. al. Phys. Rev. B, 115110 (2012).

[2] Wei, et. al. Sci. Adv. 5, eaaw6183 (2019).