Defects in an orthorhombic MoAlB MAB phase thin film grown at moderate synthesis temperature

Sahu, Rajib; Bogdanovski, Dimitri; Achenbach, Jan-Ole; Schneider, Jochen M.; Scheu, Christina

doi:10.1039/d1nr07792a

Cited by 17 publications

(17 citation statements)

References 46 publications

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“…Compared with the simulated XRD pattern, the experimental XRD result of Mo2AlB2 obtained by treatment of MoAlB/6ZnCl2 at 550℃ for 1 h is in good agreement with the theoretical prediction, suggesting the high purity of the as-synthesized Mo2AlB2. Mo4Al3B4, and Mo6Al5B6 have also been observed after deintercalation of the MoAlB precursor [24,36,37]. The selected area electron diffraction (SAED) pattern (Figure S1) confirms that the Mo2AlB2 particle is a single crystal according to the spot pattern, which could be indexed as the reflections of the orthorhombic lattice.…”

Section: (B))mentioning

confidence: 77%

Deintercalation of Al from MoAlB by molten salt etching to achieve a Mo ₂AlB ₂ compound and 2D MoB nanosheets

Mou¹,

Li²,

Zhang³

et al. 2023

Journal of Advanced Ceramics

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Two-dimensional (2D) MoB MBene has attracted much attention due to its fascinating properties and functional applications. So far work on synthesis of 2D MoB nanosheets through acid or alkaline etching of MoAlB has not been very successful. It has been proposed that 2D MoB MBene may be fabricated by chemical etching of a Mo2AlB2 precursor, but further investigations were not performed possibly due to the difficult preparation of the metastable Mo2AlB2 compound at high temperatures by solid state reactions. Here, we report on the successful synthesis of the Mo2AlB2 compound and 2D MoB nanosheets by deintercalation of Al from MoAlB through a ZnCl2Journal of Advanced Ceramics https://mc03.manuscriptcentral.com/jacer 2 molten salt etching approach at relatively low temperatures. The influences of etching temperature, etching time, and starting mixtures on the formation of desirable phases have been investigated. A pure Mo2AlB2 compound was synthesized at temperatures below 600℃, while 2D M oB M Bene nanosheets were obtained at 700℃ through the molten salt etching of MoAlB. In addition, the present work further confirms that the MoB MBene can be prepared by etching of the as-synthesized Mo2AlB2 precursor in a LiF-HCl solution. Our work demonstrates that the molten salt etching is an effective method to prepare 2D MoB MBene.

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Section: (B))mentioning

confidence: 77%

Deintercalation of Al from MoAlB by molten salt etching to achieve a Mo ₂AlB ₂ compound and 2D MoB nanosheets

Mou¹,

Li²,

Zhang³

et al. 2023

Journal of Advanced Ceramics

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“…We calculated the structural parameters of MoAlB as a = 3.22, b = 14.11, and c = 3.12 Å, in line with experiments. 21 We then focused on the stability and structural properties of both stoichiometric and nonstoichiometric surfaces. We examined all possible symmetrical stoichiometric and nonstoichiometric low-index surfaces and used calculated surface energies to identify the most stable surfaces.…”

Section: ■ Computational Methodsmentioning

confidence: 99%

First-Principles Investigation of Oxidation Mechanisms in MoAlB

Samanta,

Çakır

2023

J. Phys. Chem. C

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MoAlB’s remarkable oxidation resistance, attributed to a protective Al2O3 scale, necessitates computational analysis for deeper insights into its oxidation mechanisms. We examined the initial oxidation of low-energy MoAlB surfaces under varying conditions. The (010) surface, Al-terminated and the most stable, was identified through surface energy calculations. We explored defect formation, noting the sensitivity of Al, Mo, and B vacancies to surface termination and position. Different surfaces displayed distinct defect energetics, influencing oxidation reactions and products. For instance, Al vacancy formation on the (111) surface was less favorable than that in bulk MoAlB but more favorable on the (010) surface. Mo vacancy formation was enhanced near the surface. O2 dissociatively adsorbed on all surfaces, with strong binding energies. We calculated diffusion barriers for Al vacancies and O atoms, revealing the crucial role of Al vacancies in oxidation. Energetics of the oxidation reactions indicated that Al2O3 formation involves sequential reactions. Molecular dynamics simulations at various temperatures highlighted the complex, termination-dependent oxidation of MoAlB surfaces. For instance, the (010) surface may favor MoO2 and MoO3 formation. Our study provides valuable atomic-level insights into MoAlB surface stability, structure, and oxidation behavior.

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Section: Resultsmentioning

confidence: 99%

“…Similar formation of metastable phases which were only slightly energetically disfavored has been previously observed for fcc-(Ti,Al)N with varying Ti/Al ratios, agreeing with theoretical predictions, 21 as well as, recently, in orthorhombic MoAlB thin films, in which a twodimensional MoB phase (MBene) and several metastable defects, which are energetically disfavored, coexist in the main phase. 10,46 In the case of MoAlB (Fig. 3b), all examined competing phases are thermodynamically disfavored, explaining the stability of said compound and its experimentally observed phasepure formation; 6,7,14 however, the competing MoB phase is energetically very close at higher temperatures, and, if the curve is extrapolated, eventually likely forms instead of MoAlB, or as a main phase in a MoB/MoAlB/Al (or Al oxide) phase mixture.…”

Section: Temperature-dependent Gibbs Energies For Cralb and Moalb Vs ...mentioning

confidence: 91%

An ab initio investigation of the temperature-dependent energetic barriers towards CrAlB and (Mo,Cr)AlB formation in a metastable synthesis scenario

2022

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Defects in an orthorhombic MoAlB MAB phase thin film grown at moderate synthesis temperature

Abstract: Atomic scale characterization reveals various defects in a MoAlB (MAB) phase thin film grown by DC sputtering at a synthesis temperature of 700 °C.

Cited by 17 publications

References 46 publications

Deintercalation of Al from MoAlB by molten salt etching to achieve a Mo ₂AlB ₂ compound and 2D MoB nanosheets

Deintercalation of Al from MoAlB by molten salt etching to achieve a Mo ₂AlB ₂ compound and 2D MoB nanosheets

First-Principles Investigation of Oxidation Mechanisms in MoAlB

An ab initio investigation of the temperature-dependent energetic barriers towards CrAlB and (Mo,Cr)AlB formation in a metastable synthesis scenario

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Defects in an orthorhombic MoAlB MAB phase thin film grown at moderate synthesis temperature

Abstract: Atomic scale characterization reveals various defects in a MoAlB (MAB) phase thin film grown by DC sputtering at a synthesis temperature of 700 °C.

Cited by 17 publications

References 46 publications

Deintercalation of Al from MoAlB by molten salt etching to achieve a Mo 2AlB 2 compound and 2D MoB nanosheets

Deintercalation of Al from MoAlB by molten salt etching to achieve a Mo 2AlB 2 compound and 2D MoB nanosheets

First-Principles Investigation of Oxidation Mechanisms in MoAlB

An ab initio investigation of the temperature-dependent energetic barriers towards CrAlB and (Mo,Cr)AlB formation in a metastable synthesis scenario

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Deintercalation of Al from MoAlB by molten salt etching to achieve a Mo ₂AlB ₂ compound and 2D MoB nanosheets

Deintercalation of Al from MoAlB by molten salt etching to achieve a Mo ₂AlB ₂ compound and 2D MoB nanosheets