A FIRST-PRINCIPLES INVESTIGATION OF THE SOLID-STATE PHASE-TRANSITION IN THE MO-FE SYSTEM

The first-principles linear-muffin-tin-orbital method has been applied in studying the two-step phase transition induced by ion mixing in Mo -Fe multilayers which has been observed recently. Three different stru ctures, i.e., cubic L1(2), hexagonal D0(19), and tetragonal D0(22), Of Mo3Fe have been considered in our study. The results are presented in the form of the total energy as a function of the lattice constant, t he cohesive properties, and the density of states for the three struct ures. In agreement with experiment, the L1(2) structure is found to be more stable than either the D0(19) or D0(22) structures, which indica tes the possibility of a phase transition from the hexagonal close-pac ked (hcp) to the face-centred cubic (fee) form. The predicted lattice constants of these two phases fit very well with the experimental ones . The densities of states are also used to analyse the relative stabil ity of different structures in the Mo-Fe system.