Structural stabilities of iron silicides at high pressures and temperatures

Iron silicides provide extensive applications in functional device and earth science. Very little is known about these alloys at high pressures and temperatures. Here, combining swarm-intelligence-based structure prediction methodology and quasi-harmonic approximation (QHA), we investigate Fe-Si compounds at pressures of up to 500 GPa. Evolutionary simulations correctly find the known B20-FeSi structure and some other experimentally observed compounds at atmospheric pressure and finite temperature. It is shown that among the possible iron silicides, only B2-FeSi is thermodynamically stable at high pressures, and the increasing temperature tends to stabilize B2-FeSi compound rather than other iron silicides.