Prediction of the stability of the Mn₊₁AXn phases from first principles

Title: Prediction of the stability of the Mn₊₁AXn phases from first principles
Creator: Keast, V. J.; Harris, S.; Smith, D. K.
Relation: Physical Review B Vol. 80, Issue 21
Publisher Link: http://dx.doi.org/10.1103/PhysRevB.80.214113
Publisher: American Physical Society
Resource Type: journal article
Date: 2009
Description: One of the unusual features of the Mn₊₁AXn phases (where M is a transition metal, A is a group A element, X is carbon or nitrogen, and n=1,2,3…) is that for a given M-A-X system, only certain values of n are found to occur and there is no systematic behavior between the different systems. Density-functional theory was used to verify the stability of the different phases by comparing their total energy to that of the appropriate competing phases. Five systems (Ti-Al-C, Ti-Si-C, Ti-Al-N, Ti-Si-N, and Cr-Al-C) were studied for n=1–4. Complete agreement with observed occurrences of these phases was found. Very small energy differences suggest that it may be possible to fabricate Ti₂SiC, Ti₂SiN, and Ti₃AIN₂ as metastable phases. None of the M₅AX₄ phases were predicted to occur and in all cases the α phases were found to be more energetically favorable than the β phases.
Subject: Mn+1AXn phases; Density-functional theory; stability; carbon
Identifier: http://hdl.handle.net/1959.13/916407
Identifier: uon:7986
Identifier: ISSN:1098-0121
Language: eng
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