The mechanism of formation of TaSi2/Si Janus nanoparticles from gas-phase tantalum and silicon produced through an electron-beam evaporation technique is re-evaluated using thermodynamic arguments. This new proposed mechanism may make it possible to predict other two-component systems which can produce Janus nanoparticles through electron-beam evaporation and other high-temperature gas-phase synthesis techniques. (C) 2015 Published by Elsevier B.V.