New Solid Solution MAX Phases: (Ti0.5, V0.5)3AlC2, (Nb0.5, V0.5)2AlC, (Nb0.5, V0.5)4AlC3and (Nb0.8, Zr0.2)2AlC

Naguib, Michael; Bentzel, Grady W.; Shah, Jaymeen; Halim, Joseph; Caspi, E. N.; Lu, Jun; Hultman, Lars; Barsoum, Michel W.

doi:10.1080/21663831.2014.932858

Cited by 117 publications

(42 citation statements)

References 44 publications

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“…Hu et al have reported a partial list of about 70 new MAX phases in the period 2004-2013 [7]. Recently, Naguib et al [8] reported a large number of work (68 quaternary MAX phases) on the solid solutions where existing phases are mixed. These approaches yield the new phases [9,10] and/or other ordered quaternary phases [8, 11 -14].…”

Section: Introductionmentioning

confidence: 99%

Newly synthesized Zr 2 AlC, Zr 2 (Al 0.58 Bi 0.42 )C, Zr 2 (Al 0.2 Sn 0.8 )C, and Zr 2 (Al 0.3 Sb 0.7 )C MAX phases: A DFT based first-principles study

Ali

Hossain

Jahan

et al. 2017

Computational Materials Science

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The structural, elastic, and electronic properties of newly synthesized Zr 2 (Al 0.58 Bi 0.42 )C, Zr 2 (Al 0.2 Sn 0.8 )C, and Zr 2 (Al 0.3 Sb 0.7 )C MAX nanolaminates have been studied using firstprinciples density functional theory (DFT) calculations for the first time. Theoretical Vickers hardness has also been estimated for these compounds. All the calculated results are compared with experimental data and also with that of recently discovered Zr 2 AlC phase, where available. Zr 2 (Al 0.58 Bi 0.42 )C and Zr 2 (Al 0.2 Sn 0.8 )C are the two first Bi and Sn containing MAX compounds. The calculated structural parameters are found to be in good agreement with the experimental data. The single crystal elastic constants C ij and other polycrystalline elastic coefficients have been calculated and the mechanical stabilities of these compounds have been theoretically confirmed. The bulk modulus increases and the shear modulus decreases due to partial Bi/Sn/Sb substitution for Al in Zr 2 AlC. The calculated elastic moduli show that these Bi/Sn/Sb containing MAX phases are more anisotropic than Zr 2 AlC, and have a tendency towards ductility. The Vickers hardness decreases in the Bi/Sn/Sb containing compounds. Further, the electronic band structures and electronic density of states (EDOS) are calculated and the effects of different elemental substitution on these properties are investigated. The electronic band structures show metallic characteristics with contribution predominantly coming from the Zr 4d orbitals. Partial presence of Bi/Sn/Sb atoms increases the EDOS at the Fermi level to some extent. Possible implications of the theoretical results for these recently discovered MAX nanolaminates have been discussed in detail in this paper.

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Section: Introductionmentioning

confidence: 99%

Newly synthesized Zr 2 AlC, Zr 2 (Al 0.58 Bi 0.42 )C, Zr 2 (Al 0.2 Sn 0.8 )C, and Zr 2 (Al 0.3 Sb 0.7 )C MAX phases: A DFT based first-principles study

Ali

Hossain

Jahan

et al. 2017

Computational Materials Science

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“…Although the stoichiometry is slightly off from VTi2AlC2, this prediction can be compared to the experimentally obtained (V0.5Ti0.5)3AlC2 solid solution. 21 For TiM2AlC2 in Fig. 3 …”

Section: Mti2alc2 and Tim2alc2mentioning

confidence: 99%

“…In particular, solid solutions on the M-site include, e.g., (Ti,M)2AlC where M = V, Nb, Ta, Cr, [8][9][10][11] (V,M)2AlC where M = Nb, Ta, Cr, 9,12 (Cr,Mn)2AC where A = Al, Ga, Ge, 3,[13][14][15][16][17][18][19] (Ti,V)3AC2 where A = Al, Ge, 20,21 and (V,M)4AlC3 where M = Ti, Nb. 20,21 Adding a fourth element has also been demonstrated by realization of TiCr2AlC2, 22,23 V1.5Cr1.5AlC2, 12 TiMo2AlC2, 24,25 and Ti2Mo2AlC3, 24 which all are recent discoveries of chemically ordered quaternary MAX phases, with atomic layers composed of a single element only. This raises the question why certain combinations of M elements form layered chemically ordered MAX phases, while other combinations result in a solid solution.…”

Section: Introductionmentioning

confidence: 99%

Order and disorder in quaternary atomic laminates from first-principles calculations

Dahlqvist

Rosén

2015

Phys. Chem. Chem. Phys.

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We report on the phase stability of chemically ordered and disordered quaternary MAX phases -TiMAlC, TiM2AlC2, MTi2AlC2, and Ti2M2AlC3 where M=Zr,Hf (group IV), M=V,Nb,Ta (group V), and M=Cr,Mo,W (group VI). At 0 K, layered chemically ordered structures are predicted to be stable for M from group V and VI. By taking into account the configurational entropy, an order-disorder temperature Tdisorder can be estimated. TiM2AlC2 (M=Cr,Mo,W) and Ti2M2AlC3 (M=Mo,W) are found with Tdisorder >1773 K and are hence predicted to be ordered at the typical bulk synthesis temperatures of 1773 K. Other ordered phases, even though metastable at elevated temperatures, may be synthesized by non-equilibrium methods such as thin film growth. Furthermore, phases predicted not to be stable in any form at 0 K can be stabilized at higher temperatures in a disordered form, being the case for group IV, for MTi2AlC2 (M=V,Cr,Mo), and for Ti2M2AlC3 (M=V,Ta). The stability of the layered ordered structures with M from group VI can primarily be explained by Ti breaking the energetically unfavorable stacking of M and C where M is surrounded by C in a face-centered cubic configuration, and by M having a larger electronegativity than Al resulting in fewer electrons available for populating antibonding Al-Al orbitals. The results show that these chemically ordered quaternary MAX phases allow for new elemental combinations in MAX phases, which can be used to add new properties to this family of atomic laminates and in turn prospects for tuning these properties.

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“…19 When solid solutions are taken into account, the situation is not very different. For instance, Al-containing Ti/V and Ti/Nb solid solutions exist, 20 but these do not add any new elements to those already known to bond to Al. There are few exceptions, however, wherein a solid solution contains a M element, that do not generally bond to Al, such as Zr in (Nb 0.8 ,Zr 0.2 ) 2 AlC, 20 and (Nb 0.6 ,Zr 0.4 ) 2 AlC, 21 or Mn in (Cr x ,Mn 1Àx ) 2 AlC.…”

Section: Introductionmentioning

confidence: 99%

“…For instance, Al-containing Ti/V and Ti/Nb solid solutions exist, 20 but these do not add any new elements to those already known to bond to Al. There are few exceptions, however, wherein a solid solution contains a M element, that do not generally bond to Al, such as Zr in (Nb 0.8 ,Zr 0.2 ) 2 AlC, 20 and (Nb 0.6 ,Zr 0.4 ) 2 AlC, 21 or Mn in (Cr x ,Mn 1Àx ) 2 AlC. 22,23 In all these examples, however, the mole fraction of the non-Al bonding M element is less that 0.5 of the total M-content.…”

Section: Introductionmentioning

confidence: 99%

Experimental and theoretical characterization of ordered MAX phases Mo2TiAlC2 and Mo2Ti2AlC3

Anasori

Dahlqvist

Halim

et al. 2015

Journal of Applied Physics

262

180

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Herein, we report on the phase stabilities and crystal structures of two newly discovered ordered, quaternary MAX phases-Mo 2 TiAlC 2 and Mo 2 Ti 2 AlC 3 -synthesized by mixing and heating different elemental powder mixtures of mMo:(3-m)Ti:1.1Al:2C with 1.5 m 2.2 and 2Mo: 2Ti:1.1Al:2.7C to 1600 C for 4 h under Ar flow. In general, for m ! 2 an ordered 312 phase, (Mo 2 Ti)AlC 2 , was the majority phase; for m < 2, an ordered 413 phase (Mo 2 Ti 2 )AlC 3 , was the major product. The actual chemistries determined from X-ray photoelectron spectroscopy (XPS) are Mo 2 TiAlC 1.7 and Mo 2 Ti 1.9 Al 0.9 C 2.5 , respectively. High resolution scanning transmission microscopy, XPS and Rietveld analysis of powder X-ray diffraction confirmed the general ordered stacking sequence to be Mo-Ti-Mo-Al-Mo-Ti-Mo for Mo 2 TiAlC 2 and Mo-Ti-Ti-Mo-Al-Mo-Ti-TiMo for Mo 2 Ti 2 AlC 3 , with the carbon atoms occupying the octahedral sites between the transition metal layers. Consistent with the experimental results, the theoretical calculations clearly show that M layer ordering is mostly driven by the high penalty paid in energy by having the Mo atoms surrounded by C in a face-centered configuration, i.e., in the center of the M nþ1 X n blocks. At 331 GPa and 367 GPa, respectively, the Young's moduli of the ordered Mo 2 TiAlC 2 and Mo 2 Ti 2 AlC 3 are predicted to be higher than those calculated for their ternary end members. Like most other MAX phases, because of the high density of states at the Fermi level, the resistivity measurement over 300 to 10 K for both phases showed metallic behavior. V C 2015 AIP Publishing LLC.

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New Solid Solution MAX Phases: (Ti_0.5, V_0.5)₃AlC₂, (Nb_0.5, V_0.5)₂AlC, (Nb_0.5, V_0.5)₄AlC₃and (Nb_0.8, Zr_0.2)₂AlC

Cited by 117 publications

References 44 publications

Newly synthesized Zr 2 AlC, Zr 2 (Al 0.58 Bi 0.42 )C, Zr 2 (Al 0.2 Sn 0.8 )C, and Zr 2 (Al 0.3 Sb 0.7 )C MAX phases: A DFT based first-principles study

Newly synthesized Zr 2 AlC, Zr 2 (Al 0.58 Bi 0.42 )C, Zr 2 (Al 0.2 Sn 0.8 )C, and Zr 2 (Al 0.3 Sb 0.7 )C MAX phases: A DFT based first-principles study

Order and disorder in quaternary atomic laminates from first-principles calculations

Experimental and theoretical characterization of ordered MAX phases Mo2TiAlC2 and Mo2Ti2AlC3

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