Ab initio calculations and experimental determination of the structure of Cr2AlC

Schneider, Jochen M.; Sun, Zhimei; Mertens, Rolf; Uestel, Fatih; Ahuja, Rajeev

doi:10.1016/j.ssc.2004.02.047

Cited by 188 publications

(133 citation statements)

References 24 publications

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“…The use of DFT+U methods in calculation of MAX phases was first introduced for Cr 2 AlC [8,9] primarily motivated by three observations; (i) the reported number of states at the Fermi level N(E f ) for Cr 2 AlC is among the highest of all M 2 AlC phases (calculated 6.3 -8.0 and measured 12.9 -14.5 states / eV unit cell) while the measured electrical conductivity is among the lowest [5,6,[63][64][65], (ii) Cr 2 AlC has been found to have a much higher calculated bulk modulus (> 200 GPa) as compared to measured values (138 to 165 GPa) [5,6,64,66,67], and (iii) an underestimated calculated equilibrium volume of about -1.5 % in comparison to experiment [5,6,65,67,68].…”

Section: A Methodsmentioning

confidence: 99%

Magnetic MAX phases from theory and experiments; a review

Ingason

Dahlqvist

Rosén

2016

J. Phys.: Condens. Matter

106

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This review presents MAX phases (M is a transition metal, A an A-group element, X is C or N), known for their unique combination of ceramic/metallic properties, as a recently uncovered family of novel magnetic nanolaminates. The first created magnetic MAX phases were predicted using density functional theory through evaluation of phase stability, and subsequently synthesized as heteroepitaxial thin films. All magnetic MAX phases reported to date, in bulk or thin film form, are based on Cr and/or Mn, and they include (Cr,Mn)2AlC, (Cr,Mn)2GeC, (Cr,Mn)2GaC, (Mo,Mn)2GaC, and (V,Mn)3GaC2, Cr2AlC, Cr2GeC and Mn2GaC. A variety of magnetic properties have been found, such as ferromagnetic response well above room temperature and structural changes linked to magnetic anisotropy. In this paper, theoretical as well as experimental work performed on these materials to date is critically reviewed, in terms of methods used, results acquired, and conclusions drawn. Open questions concerning magnetic characteristics are discussed, and an outlook focused on new materials, superstructures, property tailoring and further synthesis and characterization is presented.

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Section: A Methodsmentioning

confidence: 99%

Magnetic MAX phases from theory and experiments; a review

Ingason

Dahlqvist

Rosén

2016

J. Phys.: Condens. Matter

106

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“…Cr 2 AlC films can be produced either by sputtering from elemental targets [30][31][32] or compound targets [10,33]. Literature indicates advantages of lower deposition temperatures for Cr 2 AlC [33] in contrast to other MAX phase coatings, like Ti 2 AlC and Ti 3 AlC 2 [34], which is promising for deposition on heat-sensitive substrates, such as steel.…”

Section: Introductionmentioning

confidence: 99%

Sputtering Power Effects on Growth and Mechanical Properties of Cr2AlC MAX Phase Coatings

Naveed

Obrosov

Żak

et al. 2016

Metals

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Abstract:Coating growth and mechanical properties of nanolamellar Cr 2 AlC coatings at various sputtering power were investigated in the present study. Cr 2 AlC coating was deposited on the IN 718 superalloy and (100) Si wafers by DC magnetron sputtering at different sputtering powers. The structure and properties were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and nanoindentation. It was found that coatings had columnar structure with nanocrystalline substructure. Deposition rate increased with the sputtering power. XRD results showed the presence of the Cr 2 AlC MAX phase, intermetallic AlCr 2 and Cr 7 C 3 carbide phases, along with the change in preferential coating growth orientation. TEM observations confirmed the occurrence of these phases, and the SAED patterns demonstrated significant texture of the coatings. Hardness values were measured in the range between 11-14 GPa, showing a slight increase with the sputtering power.

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“…13 However, to the best of our knowledge, none have experimentally been demonstrated to show magnetic behavior. The few theoretical studies available [14][15][16] have not been able to identify suitable thermodynamically stable candidates, and hence the task of predicting a stable magnetic MAX phase is still open.…”

mentioning

confidence: 99%

Magnetic nanoscale laminates with tunable exchange coupling from first principles

et al. 2011

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The M(n+1)AX(n) (MAX) phases are nanolaminated compounds with a unique combination of metallic and ceramic properties, not yet including magnetism. We carry out a systematic theoretical study of potential magnetic MAX phases and predict the existence of stable magnetic (Cr(1-x)Mn(x))(2)AlC alloys. We show that in this system ferromagnetically ordered Mn layers are exchange coupled via nearly nonmagnetic Cr layers, forming an inherent structure of atomic-thin magnetic multilayers, and that the degree of disorder between Cr and Mn in the alloy can be used to tune the sign and magnitude of the coupling

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Ab initio calculations and experimental determination of the structure of Cr2AlC

Cited by 188 publications

References 24 publications

Magnetic MAX phases from theory and experiments; a review

Magnetic MAX phases from theory and experiments; a review

Sputtering Power Effects on Growth and Mechanical Properties of Cr2AlC MAX Phase Coatings

Magnetic nanoscale laminates with tunable exchange coupling from first principles

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