Mechanical properties of thermoelectric n-type magnesium silicide synthesized employing<i>in situ</i>spark plasma reaction sintering

Abstract

Thermoelectric devices employing magnesium silicide (Mg2Si) offer an inexpensive and non-toxic solution for green energy generation compared to other existing conventional thermoelectric materials in the mid-temperature range. However, apart from the thermoelectric performance, their mechanical properties are equally important in order to avoid the catastrophic failure of their modules during actual operation. In the present study, we report the synthesis of Mg2Si co-doped with Bi and Sb employing in situ spark plasma reaction sintering and investigate its broad range of mechanical properties. The mechanical properties of the sintered co-doped Mg2Si suggest a significantly enhanced value of hardness ~5.4 ± 0.2 GPa and an elastic modulus ~142.5 ± 6 GPa with a fracture toughness of ~1.71 ± 0.1 MPa √m. The thermal shock resistance, which is one of the most vital parameter for designing thermoelectric devices, was found to be ~300 W m−1, which is higher than most of the other existing state-of-the-art mid-temperature thermoelectric materials. The friction and wear characteristics of sintered co-doped Mg2Si have been reported for the first time, in order to realize the sustainability of their thermoelectric modules under actual hostile environmental conditions.