Structural properties of non-stoichiometric Fe–Ti–Sn and Fe–V–Al Heusler alloys

It was suggested recently [Anand et al., Energy Env. Sci. 11 (2018) 1480] that single-phase half-Heusler compounds can be obtained from structurally unstable alloys having 19 valence electrons by introducing defects to adjust their valence electrons count to 18. In our work we extend this approach to Fe–V–Al and Fe–Ti–Sn full-Heusler alloys. Structural investigation of the prepared alloys indicated that the non-stoichiometric Fe–Ti–Sn with nominal VEC = 18 is a multiphase compound while the non-stoichiometric Fe–V–Al exists as a single-phase compound. Crystal structure of the studied Fe–V–Al was found to be cubic with the lattice parameter a = 0.5815 nm, which is slightly larger as compared to the stoichiometric Fe 2 VAl full-Heusler alloy. Our finding opens up a new window for the design of previously unknown thermoelectric Heusler alloys. Graphical abstract