Elastic mechanical thermodynamic and thermoelectric properties of pristine and titanium doped Mg₂Si: a density functional theory study

Herein, we report a systematic investigation of the effect of Titanium doping on the structural, elastic, mechanical, thermodynamic, and thermoelectric (TE) dynamics of Mg₂Si Compounds using first-principle investigation. The present study has been carried out using the full potential linearized augmented plane wave method as implemented in<i>Wien2k</i>code under<i>mBJ</i>exchange potentials. The investigations revealed that Mg_2-<i>x</i>Ti<i>_x</i>Si compounds have structural stability with cubic phase (<i>Fm-3m</i>symmetry) and possess degenerate semiconducting nature. The analysis of elastic constants revealed mechanical stability of the investigated compounds following Born criteria. Thermodynamic investigations have been carried out in the temperature range of 100-1500 K at zero pressure and the quantities like heat capacity, Debye temperature, Grüneisen constant, and thermal expansion coefficient have been critically analyzed. Lastly, the TE performance of Mg_2-<i>x</i>Ti<i>_x</i>Si compounds has been predicted by estimating the thermopower (<i>S</i>²<i>σ</i>) and TE figure of merit (<i>zT</i>) in the temperature range of 300-1500 K. The predicted value of<i>zT</i>_maxfor Mg_2-<i>x</i>Ti<i>_x</i>Si compound is 0.67 at 800 K for<i>x</i>= 0.25 titanium content, suggesting materials promising application for TE energy harvesting and mechanical devices.