Theoretical and experimental study of the phase formation for Ti2YAl and Ti2Y′Ga (Y = Co, Fe; Y′ = Cr, Fe). (June 2016) - Zhang, X.J.
Abstract: The site preference and phase formation of Ti2 YAl and Ti2 Y′Ga (Y = Co, Fe; Y′ = Cr, Fe) have been investigated by theoretical calculation and experimental study. It has been found that Ti2 CoAl and Ti2 FeAl are stable in Hg2 CuTi-type structure, while Ti2 CrGa and Ti2 FeGa compounds are most likely to form Cu2 MnAl-type structure. These results indicate that not all full-Heusler alloys follow the site preference rule, especially when the transition metals are low-valent metals. The differences of band structures and magnetic properties between Hg2 CuTi-type and Cu2 MnAl-type structures for the above compounds are also studied by first-principles calculation. It has been predicted that Ti2 FeAl, Ti2 FeGa and Ti2 CoAl are half-metallic compounds in Hg2 CuTi-type structure, while their half-metallic properties are completely destroyed as they formed Cu2 MnAl-type structure. Highlights: Ti2 -based Heusler alloys are not necessarily formed in inverse Heusler structure. Half-metallic property is very sensitive to atomic occupation. Hg2 CuTi-type structure is most favored for Ti2 FeAl and Ti2 CoAl. Ti2 CrGa and Ti2 FeGa compounds are most likely to form in Cu2 MnAl-type structure.