Enhanced thermoelectric properties of pristine CrSi2 synthesized using a facile single-step spark plasma assisted reaction sintering

The current study reports a single-step synthesis of thermoelectric material p-type chromium di-silicide (CrSi2), using reaction sintering of their elemental powders employing spark plasma assisted sintering at optimized processing parameters. This process of single-step synthesis takes only a few minutes in contrast to the conventional processes reported earlier, which take several hours and involve multi-step processing, including arc-melting and/or mechanical alloying followed by spark plasma sintering/hot pressing. Despite employing a facile single-step synthesis process, an enhanced state-of-the-art thermoelectric figure of merit (ZT) ~ 0.19 at 673 K was achieved in pristine single phase CrSi2, which is the highest reported thus far in pristine CrSi2 at this temperature. It was observed that in order to compensate for the loss of Si during high temperature processing, 2.5 at.% of excess Si was found to be optimum in order to obtain a single-phase CrSi2. The synthesized CrSi2 samples were characterized using X-ray diffraction, Field emission scanning electron microscopy and Energy dispersive X-ray spectroscopy, based on which their enhancement of thermoelectric properties has been discussed.