First-principles investigation of phase stability and electronic structure of tetragonal (P4/m) Ga_(3_x)Al_xTi_2 (x=0-3) compounds

摘要

We report a first-principles study of the phase stability and electronic structure of tetragonal (P4/m) Ga_(3_x)Al_xTi_2 (x=0-3) compounds to investigate the conspicuous absence of Al_3Ti_2 in the Al-Ti phase diagram while isostructural Ga_3Ti_2 is stable in the Ga-Ti phase diagram. It is found that Ga_3Ti_2 is the most stable phase compared to its ternary derivatives (Ga_(3_x)Al_x)Ti_2, with the stability of Al_3Ti_2 being the lowest. Furthermore, the equimolecular phase mixture of y-TLAl and r-Al_2Ti is found to be more stable than Al_3Ti_2. By analysing the total and partial density of states, the valence charge transfer and the valence charge density distributions, we substantiate our conclusions from the perspective of the electronic structure.