Structural features and thermoelectric properties of spark plasma assisted combustion synthesised Magnesium silicide doped with Aluminium

Abstract Magnesium silicide (Mg2Si) is a promising and greener thermoelectric material for the mid-temperature application. However, synthesising Mg2Si compound is a challenging task through the conventional approaches as it is confronts with realistic hurdles such as volitation and an oxidation consequence in the unstoichiometric chemistry resulting the detrimental effect in the thermoelectric properties. The current work details the successful and swift approach (~54 min) combining in-situ synthesis and simultaneous densification of Mg2Si with substantial doping of aluminium (Al) (0.005 at.% – 0.030 at.%) through spark plasma assisted combustion synthesis approach. X-ray diffraction (XRD) and electron microscopy analyses concede the Mg2Si phase evolution with homogeneous doping of Al. The synthesised nanocrystalline Mg2Si showcases the superior density (>95%). The n-type Mg2Si doped with Al of 0.030 at.% shows the synergistic improvement in power factor (7.84 × 10−4 W/mK2) with the significant reduction in the thermal conductivity (2.01 W/mK) thus achieved the Figure of merit (ZT) of 0.32 at 550 °C which is significantly higher than the Mg2Si intrinsic compound possessing the ZT of 0.11.