Heterogeneous Interface Microstructure and Thermoelectromagnetic Conversion Performance of BiSbTe/MnCoGe Multifunctional Materials

Abstract

The synergistic cooling of thermoelectromagnetic materials promises a breakthrough in the efficiency of single refrigeration and has attracted extensive research. The study of heterogeneous interface is crucial for achieving the synergistic performance of both materials. In this work, a composite material comprising Bi₂Te₃-based thermoelectric material and MnCoGe-based magnetocaloric material is synthesized, which is a material exhibiting both thermoelectric and magnetocaloric properties. During the plasma-activated sintering process of the composite material, elemental interdiffusion of Mn, Co, Sb, and Te occurs, forming a diffusion layer of MnTe and CoSbTe. Reaction of heterogeneous interface leads to point defects within the material, significantly increasing the carrier concentration. Optimization of the sintering temperature results in a thermoelectric figure of merit (ZT) of 0.69 at 300 K and −ΔS_max of 0.97 J kg⁻¹ K⁻¹ at room temperature under a 5 T magnetic field for the Bi_0.5Sb_1.5Te₃/10 wt% Mn_0.9Cu_0.1CoGe composite sintered at 623 K and under 50 MPa. This study demonstrates that Bi_0.5Sb_1.5Te₃/Mn_0.9Cu_0.1CoGe is a potential candidate for efficient thermoelectromagnetic cooling applications.