Electronic structure, bonding characteristics, and mechanical properties in (W2/3Sc1/3)2AlC and (W2/3Y1/3)2AlC i-MAX phases from first-principles calculations. (3rd July 2018)

• Record Type: Journal Article
• Authors: Dahlqvist, Martin; Thore, Andreas; Rosen, Johanna
• Is Part Of: Journal of physics. Volume 30:Number 30(2018)
• Publication Date: 2018-07-03
• Subjects: atomic laminate -- MAX phase -- chemical order -- electronic structure -- first-principles calculations -- bond analysis; Condensed matter -- Periodicals; Matière condensée -- Périodiques; Vaste stoffen; Vloeistoffen; Natuurkunde; Electronic journals; Computer network resources; 530.4105
• DOI: 10.1088/1361-648X/aacc19
• Languages: English
• ISSNs: 0953-8984

Abstract

Abstract: With the recent discovery of in-plane chemically ordered MAX phases ( i -MAX) of the general formula ( )2 A C comes addition of non-traditional MAX phase elements. In the present study, we use density functional theory calculations to investigate the electronic structure, bonding nature, and mechanical properties of the novel (W2/3 Sc1/3 )2 AlC and (W2/3 Y1/3 )2 AlC i -MAX phases. From analysis of the electronic structure and projected crystal orbital Hamilton populations, we show that the metallic i -MAX phases have significant hybridization between W and C, as well as Sc(Y) and C states, indicative of strong covalent bonding. Substitution of Sc for Y ( M 2 ) leads to reduced bonding strength for W–C and Al–Al interactions while M 2 –C and M 2 –Al interactions are strengthened. We also compare the Voigt–Reuss–Hill bulk, shear, and Young's moduli along the series of M 1 = Cr, Mo, and W, and relate these trends to the bonding interactions. Furthermore, we find overall larger moduli for Sc-based i -MAX phases.