Mo-Fe/NbFeSb Thermoelectric Junctions: Anti-Thermal Aging Interface and Low Contact Resistivity.

In recent years, high-performance half-Heusler compounds have been developed as promising thermoelectric materials for power generation. Aiming at practical device applications, one key step is to seek suitable metal electrodes so that low interfacial resistivity is guaranteed under long-term thermal aging. In the previous work, the fresh Mo/NbTiFeSb junction was found exhibiting low contact resistivity below 1 μΩ cm; however, it increased by tens of times under long-term thermal aging, mainly originating from the formation of the high-resistivity FeSb phase and the appearance of cracks. Here, the Mo-Fe electrodes are employed to build the junctions with NbTiFeSb. The interfacial behavior and contact resistance in these junctions were investigated both before and after the thermal aging. Interestingly, no obvious formation of FeSb phase and cracks were observed. As a result, the contact resistivity was below ∼1 μΩ cm after 15 days' thermal aging, indicating better connection reliability and lower contact resistivity compared to the Mo/NbTiFeSb junction. These findings highlight the applicability of Mo-Fe electrodes and pave the way for NbFeSb-based half-Heusler thermoelectric materials for device applications.