Effects of different rare earth elements in tuning the thermoelectric properties of RIr₂Zn₂₀ (R= rare earth)

Over the past several decades, the 1-2-20 class of materials has been heavily studied. The interest in these materials stems from the fact that they exhibit many exotic physical properties and are highly tunable. The 1-2-20 structure is composed of f-block elements and transition metal elements, encompassed by a large cage-like frame. In some variants, the strongly hybridized f-electron states at the Fermi level result in large Seebeck coefficient values, making this system a promising candidate for thermoelectric applications [1, 2]. In this study, we synthesized large single crystals of RIr₂Zn₂₀ (R = rare earth) using the molten metal flux growth technique. By introducing different rare earth elements, we observed a strong correlation between the f-electron states and the behavior of the temperature-dependent Seebeck coefficient. Detailed characterizations on electrical, thermal transport, and magnetic properties will be presented in order to understand such correlation and improve the overall thermoelectric properties of these materials.