Enhanced Thermoelectric Properties of 1-2-20 Compounds through Multi-filler Approach

Thermoelectric materials hold tremendous promise for advances in fundamental science and future applications; particularly for robust electricity generation in extreme and remote environments. Despite these advantages, for most materials the energy conversion efficiency is limited by the natural proportionality between the electrical and thermal conductivities and that the Seebeck coefficient of metals tends to be small. I will report the latest results for the continuous study of the heavy-fermion compounds YbTM₂Zn₂₀ (TM = Co, Rh, Ir) which exhibit a large power factor and a high thermoelectric figure of merit, ZT, at 35 K. [1] Through further compositional modifications by introducing multiple fillers, significantly improved ZT values are achieved. The combination of the strongly hybridized f-electron state and the novel structural features (large unit cell and possible soft phonon modes) leads to the realization of “phonon glass/electron crystal” behavior and suggests that these systems could provide a platform for the next generation of low-temperature thermoelectric materials.

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