[TuP3E] E. Physics, spintronics, and novel device concepts

[TuP3E-07] Thermoelectric Property mapping for High-performance Integrated MgAgSb-MgCuSb System

〇JIANKANG LI¹, Airan LI¹, Longquan Wang¹, Takao Mori^1,2 (1. National Inst. for Materials Sci. (Japan), 2. The Univ. of Tsukuba (Japan))

To achieve high conversion efficiency in thermoelectric (TE) modules, not only the thermoelectric materials (TEMs) with a high figure of merit (zT) but also the optimization of interface materials (TEiMs) is required. For TEMs, enhancing zT relies on increasing the power factor (PF) and lowering the total thermal conductivity (κ), while for TEiMs, high electrical conductivity (σ) and κ are essential to reduce energy loss during heat and charge transport, which highlights the importance of the integrated design of TEMs and TEiMs. In this work, we select p-type MgAgSb as the object and construct a TE property mapping of the integrated MgAgSb–MgCuSb two-phase system by tuning the Ag/Cu ratio. Based on the property mapping, Ag-rich compositions exhibit superior PF and zT values, underscoring their potential for efficient energy conversion. Conversely, Cu-rich compositions possess substantially higher electrical and thermal conductivities, rendering them promising as TEiM. As a result, a high PF of ~ 21 μW cm⁻¹ K⁻² at 323 K, as well as a competitive zT of 1.12 at 473 K, are obtained in x = 0.97, proving its optimal potential as TE material. The x = 0.05 is identified as the optimal TEiM not only for the lower contact resistance in the corresponding TE leg, but also for its superior carrier and phonon transport properties. As a result, a two-pair module is also successfully fabricated, yielding a peak conversion efficiency of ~7.2%, thereby advancing the performance of current Mg-based TE modules.