Review: Transition metal-based nanolamellar phases

Demyashev, Gregory M.

doi:10.1016/j.pmatsci.2010.02.002

Cited by 33 publications

(28 citation statements)

References 154 publications

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“…Since carbon content affects bonding, beyond the properties briefly discussed above, it also governs the structure of the phases. The change in the C/M ratio facilitates a range of interesting structures that give rise to complex phase diagrams in the carbides and results in considerable debate on the equilibrium structures that form as the carbides become ever more substoichiometric …”

Section: Introductionmentioning

confidence: 96%

Review of phase stability in the group IVB and VB transition‐metal carbides

Weinberger

Thompson

2018

J Am Ceram Soc

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This review summarizes the phase stability in the group IVB (Ti‐C; Zr‐C; Hf‐C) and group VB (V‐C; Nb‐C; Ta‐C) transition‐metal carbides. The order parameter functional (OPF) method and density functional theory (DFT) method have been used to predict phase equilibria in these systems. Extensive experimental investigations have attempted to determine both phase stability as a function of composition as well the crystal structures present using X‐ray diffraction, neutron diffraction, electron backscatter detection, and selected area electron diffraction. These investigations have demonstrated that the structures that form are based on the close‐packing of the metal atoms and the arrangement of the carbon atoms in the octahedral interstices. In general, the rocksalt B1 phase is stable for all of the transition‐metal carbides, with their substoichiometry tolerance increasing with temperature; vanadium carbide is the exception due to its negative vacancy formation energy. Vacancy‐ordered M6C5 phases have been predicted and experimentally confirmed in both groups of carbides; however, kinetic limitations often inhibit the formation of vacancy‐ordered phases, which has contributed to controversy in phase identification. The vacancy‐ordered M4C3 phase has been predicted for select carbides and has only been observed in zirconium carbide. In contrast, the stacking fault phase ζ‐M4C3−x has been readily reported in the group VB carbides (but not in the group IVB carbides). The vacancy‐ordered M3C2 has been predicted by DFT for the group IVB carbides but not in the group VB carbides, whereas OPF predicts its stability in both carbides. Vacancy‐ordered M3C2 phases have been experimentally observed in the Ti‐C and Hf‐C systems. Finally, the M2C phase has been predicted in both group carbides, except for hafnium carbide, with an order‐disorder transition with temperature. These factors result in phase diagrams that are similar among all the carbides, but each phase diagram is unique due to subtle differences in bonding that result in slight differences in thermodynamically stable phases.

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Section: Introductionmentioning

confidence: 96%

Review of phase stability in the group IVB and VB transition‐metal carbides

Weinberger

Thompson

2018

J Am Ceram Soc

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“…Another interesting set of the carbon/nitrogen depleted phases that form between the MX and M 2 X compositions have been collectively described by Demyashev as the nanolamellar stacking fault phases (SFPs) [9]. These phases are also related to the B1 structure, just as the vacancy ordered phases are, however they involve the formation of layers of non-metal vacancies accompanied by the formation of a stacking fault.…”

Section: Introductionmentioning

confidence: 99%

“…These phases would all be related back to the parent B1 structure and can be formed from it by a coupled non-metal atom depletion and associated shear. For example, Demyashev has postulated a M 6 X 5 SFP whose existence has yet to be verified [9]. It is also possible to postulate the existence of other related SFPs such as a M 7 X 6 phase, M 8 X 7 phase and so on.…”

Section: Introductionmentioning

confidence: 99%

A model for understanding the formation energies of nanolamellar phases in transition metal carbides and nitrides

Guziewski

Thompson

et al. 2016

Modelling Simul. Mater. Sci. Eng.

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Abstract. In this paper we introduce a stacking-fault based model to understand the energetics of formation of the nanolamellar-based metal carbide and nitride structures. The model is able to reproduce the cohesive energies of the stacking fault phases from Density Functional Theory calculations by fitting the energy of different stacking sequences of metal layers. The model demonstrates that the first and second nearest metal-metal neighbor interactions and the nearest metal-carbon/nitrogen interaction are the dominant terms in determining the cohesive energy of these structures. The model further demonstrates that above a metal to non-metal ratio of 75%, there is no energetic favorability for the stacking faults to form a long-range ordered structure. The model's applicability is demonstrated using the Ta-C system as its case study from which we report that the interfacial energy between ζ-Ta 4 C 3 and TaC or Ta 2 C is negligible. Our results suggest that the closed packed planes of these phases should be aligned and that precipitated phases should be thin, which is in agreement with experiments.

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“…1,2 It was discovered that a fluid confined in a nanostructure exhibits unique characteristics, such as the "grainy" structure, 3 the "single-file" transport phenomena, 4 and the enhanced flow rate. [5][6][7] A large number of nanofluidic devices, including nanochannels, nanoarrays, nanolameli, and nanoslits, [8][9][10][11][12] have been developed and employed for material separation, thermal and electrical conduction, biosensor, fluid transportation, and fuel cell fabrication, [13][14][15][16][17][18] among others.…”

Section: Introductionmentioning

confidence: 99%

An experimental investigation on fluidic behaviors in a two-dimensional nanoenvironment

Qiao

2013

Journal of Applied Physics

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Behaviors of liquids in two-dimensional (2D), lyophobic nanoenvironment were investigated experimentally by using a surface-modified, graphene-based nanoslit composite (GBNC). Different from previous reports on one-dimensional (1D) nanofludic behaviors, the infiltration pressure of 2D nanofluid is not dependent on the infiltration volume, leading to a flat infiltration plateau in the sorption isotherm curve. This unique phenomenon implies that, compared with a 1D nanoenvironment, more energetically favorable molecular configurations may be formed in a 2D nanoslit, probably due to the relaxation of the lateral confinement. V C 2013 AIP Publishing LLC.

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Review: Transition metal-based nanolamellar phases

Cited by 33 publications

References 154 publications

Review of phase stability in the group IVB and VB transition‐metal carbides

Review of phase stability in the group IVB and VB transition‐metal carbides

A model for understanding the formation energies of nanolamellar phases in transition metal carbides and nitrides

An experimental investigation on fluidic behaviors in a two-dimensional nanoenvironment

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