What is the true ground state of intermetallic compound Fe3Al?

• Published in: Solid state sciences Vol. 157; p. 107709
• Main Authors: Všianská, M., Šob, M.
• Format: Journal Article
• Language: English
• Published: Elsevier Masson SAS 01-11-2024
• ISSN: 1293-2558
• DOI: 10.1016/j.solidstatesciences.2024.107709

We discuss recent doubts about the true ground-state (GS) structure of the intermetallic compound Fe3Al. It seems that it should be the D03 structure (observed experimentally), but there are some considerations that, perhaps, D03 might be a high-temperature (>400 K) structure and the GS at 0 K might be the L12 structure because there might be a high energy barrier between both structures and, when the temperature is lowered, the system is not able to transform into the (perhaps) lower-energy L12 structure. To elucidate this problem, we re-interpret our recent extended ab initio electronic structure calculations for Fe3Al performed with the help of the VASP code and using various exchange-correlation energies within the generalized gradient approximation (GGA). Regrettably, some calculations provide the L12 and some of them D03 as the GS structure.
To resolve this question, we performed further calculations testing 9 frequently applied metaGGAs, such as TPSS, revTPSS, M06-L, SCAN(-L), rSCAN(-L) and r2SCAN(-L) representing a higher rung of the Jacob's ladder. It turns out that also here some meta-GGAs lead to L12 and some others to D03 GS structure and, again, we cannot decide.
In this way, the present results represent the very first step on the way to understand the energetics of the Fe3Al compound and its ground state. We hope they may motivate future theoretical and experimental work in this direction.
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•We address a long-term problem regarding the correct ground-state crystal structure of the Fe3Al intermetallic compound.•Various parametrizations of GGAs and metaGGAs were tested.•It is not possible to decide whether the ground-state structure of Fe3Al compound should be D03 or L12.•We hope that the present results may stimulate future theoretical and experimental work in this direction.