Computational discovery of stable M2AX phases

Michael Ashton, Richard G. Hennig, Scott R. Broderick, Krishna Rajan, and Susan B. Sinnott
Phys. Rev. B 94, 054116 – Published 31 August 2016

Abstract

The family of layered Mn+1AXn compounds provides a large class of materials with applications ranging from magnets to high-temperature coatings to nuclear cladding. In this work, we employ a density-functional-theory-based discovery approach to identify a large number of thermodynamically stable Mn+1AXn compounds, where n=1, M=Sc, Ti, V, Cr, Zr, Nb, Mo, Hf, Ta; A=Al, Si, P, S, Ga, Ge, As, Cd, In, Sn, Tl, Pb; and X=C, N. We calculate the formation energy for 216 pure M2AX compounds and 10 314 solid solutions, (MM)2(AA)(XX), relative to their competing phases. We find that the 49 experimentally known M2AX phases exhibit formation energies of less than 30 meV/atom. Among the 10 530 compositions considered, 3140 exhibit formation energies below 30 meV/atom, most of which have yet to be experimentally synthesized. A significant subset of 301 compositions exhibits strong exothermic stability in excess of 100 meV/atom, indicating favorable synthesis conditions. We identify empirical design rules for stable M2AX compounds. Among the metastable M2AX compounds are two Cr-based compounds with ferromagnetic ordering and expected Curie temperatures around 75 K. These results can serve as a map for the experimental design and synthesis of different M2AX compounds.

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  • Received 21 June 2016

DOI:https://doi.org/10.1103/PhysRevB.94.054116

©2016 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Michael Ashton and Richard G. Hennig

  • Department of Materials Science and Engineering, University of Florida, Gainesville, Florida 32611-6400, USA

Scott R. Broderick and Krishna Rajan

  • Department of Materials Design and Innovation, University at Buffalo, The State University of New York, Buffalo, New York 14260, USA

Susan B. Sinnott

  • Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16801-7003, USA

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Issue

Vol. 94, Iss. 5 — 1 August 2016

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