Phase stability and initial low-temperature oxidation mechanism of Ti2AlC thin films

The effect of low energy ion irradiation in the nanolaminated Ti 3 AlC 2 is investigated by means of X-ray diffraction, transmission electron microscopy, electron energy loss and X-ray absorption spectroscopy. The chemical sensitivity and local order probing from core-loss edges provide new insight in the undertanding of structural modifications induced under irradiation. From the analysis of the C K energy loss near edge structure (ELNES) and Al K X-ray absorption near edge structure (XANES) by ab initio calculations, the influence of the layered structure of this compound on the irradiation damage is demonstrated, with preferentialy localized damage in aluminum planes of the structure. On the basis of comparisons between calculations and the experimental spectra, a strutural model is proposed for the irradiated state. This study emphasizes the utility of core-loss fine structure analysis to further understanding of ion irradiation induced damage in complex crystalline materials.

show abstract

“…the observations in Refs. [39,43,44]). The Ti 3 AlC 2 film was ∼ 160 nm thick, as measured from TEM observations.…”

Section: Methodsmentioning

confidence: 99%

Contribution of core-loss fine structures to the characterization of ion irradiation damages in the nanolaminated ceramic Ti3AlC2

et al. 2013

View full text Add to dashboard Cite

show abstract

“…elevated temperature [42] and oxidizing atmosphere [43]. It can also be an alternative method of synthesizing the MAX and related phases by annealing amorphous thin films [44][45][46] or artificial multilayers [47][48][49][50][51][52] with an overall chemical composition close to the desired phase.…”

Section: Nanolaminated Transition Metal Carbides From Thin Film Perspmentioning

confidence: 99%

“…Here, as a step towards thin film optimization, the phase composition and the crystal quality of Zr2Al3C4 thin films were studied in relations with deposition parameters applied to the synthesis process (See Paper III). [67,68] or mobile A elements out-diffusion following with the decomposition of the MAX phase [42,43,[69][70][71][72][73]. However, the reaction of Ti3SiC2 with Au results in formation of nanolaminated Ti3AuC2 and Ti3Au2C2 phases with retained Ti3C2 layers, showing a new route of modifying the MAX phases with noble metals.…”

Section: Research Motivation and Strategymentioning

confidence: 99%

“…Contrarily, Ti2AlC and Ti3AlC2 exhibits less oxidation resistance at temperature lower than ~700 °C [18,[203][204][205] but an improved oxidation resistance at temperature higher than 1000 °C, which can be described with cubic oxidation kinetics [206]. This is explained by a slower kinetic for the formation of protective Al2O3 species than the formation of rutile (Ti1-xAlx)O2-x with x < 0.05, which is poor in preventing O penetration [43,203,206].…”

Section: From Oxidation To Crack Self-healingmentioning

confidence: 99%

“…The oxidation of the MAX phases has been reported for introducing crack self-healing to the damaged materials by sealing the cracks with, primarily, oxides of the A element [43,207]. The oxidation-induced crack-healing has been realized in Ti2AlC [208][209][210][211], Ti3AlC2 [207], Cr2AlC [212][213][214], Ti2(Sn,Al)C [215], and Ti2SnC [216], by exposing the pre-notched or cracked samples to oxidizing atmosphere (air) for several hours at elevated temperature.…”

Section: From Oxidation To Crack Self-healingmentioning

confidence: 99%

See 2 more Smart Citations

Phase Formation of Nanolaminated Transition Metal Carbide Thin Films

Lai¹

View full text Add to dashboard Cite

The cover image is a simple sketch of structural-chemical relation in between the metal layers in nanolaminated transition metal carbides: Mo2GaC, Mo2Ga2C, and Mo2(Au1-xGax)2C with an in-plane order in the Au-Ga layers, where the last two phases were discovered in this thesis. © Chung-Chuan Lai 2017Printed in Sweden by LiU-Tryck 2017 ISSN 0345-7524 ISBN 978-91-7685-526-3 i AbstractResearch on inherently nanolaminated transition metal carbides is inspired by their unique properties combining metals and ceramics, such as higher damage tolerance, better machinability and lower brittleness compared to the binary counterparts, yet retaining the metallic conductivity. The interesting properties are related to their laminated structure, composed of transition-metal carbide layers interleaved by non-transition-metal (carbide) layers. These materials in thin-film form are particularly interesting for potential applications such as protective coatings and electrical contacts. The goal of this work is to explore nanolaminated transition metal carbides from the aspects of phase formation and crystal growth during thin-film synthesis. This was realized by studying phases in select material systems synthesized from two major approaches, namely, from direct-deposition and post-deposition treatment.The first approach was used in studies on the Mo-Ga-C and Zr-Al-C systems. In the former system, intriguing properties have been predicted for the 3D phases and their 2D derivatives (so called MXenes), while in the latter system, the phases are interesting for nuclear applications.In this work, the discovery of a new Mo-based nanolaminated ternary carbide, Mo2Ga2C, is evidenced from thin-film and bulk processes. Its structure was determined using theoretical and experimental techniques, showing that Mo2Ga2C has Ga double-layers in simple hexagonal stacking between adjacent Mo2C layers, and therefore is structurally very similar to Mo2GaC, except for the additional Ga layers. For the Zr-Al-C system, the optimization of phase composition and structure of Zr2Al3C4 in a thin-film deposition process was studied by evaluating the effect of deposition parameters. I concluded that the formation of Zr2Al3C4 is favored with a plasma flux overstoichiometric in Al, and with a minimum lattice-mismatch to the substrates. Consequently, epitaxial Zr2Al3C4 thin film of high quality were deposited on 4H-SiC(001) substrates at 800 °C.With the approach of post-deposition treatment, the studies were focused on a new method of thermally-induced selective substitution reaction of Au for the non-transition-metal layers in nanolaminated carbides. Here, the reaction mechanism has been explored in Al-containing (Ti2AlC and Ti3AlC2) and Ga-containing (Mo2GaC and Mo2Ga2C) phases. The Al and Ga in ii these phases were selectively replaced by Au while the carbide layers remained intact, resulting in the formation of new layered phases, Ti2Au2C, Ti3Au2C2, Mo2AuC, and Mo2(Au1-xGax)2C, respectively. The substitution reaction was explained by fast outward diffus...

show abstract

Butane Dry Reforming Catalyzed by Cobalt Oxide Supported on Ti₂AlC MAX Phase

et al. 2020

View full text Add to dashboard Cite

MAX (M n + 1 AX n) phases are layered carbides or nitrides with a high thermal and mechanical bulk stability. Recently, it was shown that their surface structure can be modified to form a thin non-stoichiometric oxide layer, which can catalyze the oxidative dehydrogenation of butane. Here, the use of a Ti 2 AlC MAX phase as a support for cobalt oxide was explored for the dry reforming of butane with CO 2 , comparing this new catalyst to more traditional materials. The catalyst was active and selective to synthesis gas. Although the surface structure changed during the reaction, the activity remained stable. Under the same conditions, a titania-supported cobalt oxide catalyst gave low activity and stability due to the agglomeration of cobalt oxide particles. The Co 3 O 4 /Al 2 O 3 catalyst was active, but the acidic surface led to a faster deactivation. The less acidic surface of the Ti 2 AlC was better at inhibiting coke formation. Thanks to their thermal stability and acid-base properties, MAX phases are promising supports for CO 2 conversion reactions.

show abstract

Phase stability and initial low-temperature oxidation mechanism of Ti2AlC thin films

Cited by 47 publications

References 50 publications

Contribution of core-loss fine structures to the characterization of ion irradiation damages in the nanolaminated ceramic Ti3AlC2

Contribution of core-loss fine structures to the characterization of ion irradiation damages in the nanolaminated ceramic Ti3AlC2

Phase Formation of Nanolaminated Transition Metal Carbide Thin Films

Butane Dry Reforming Catalyzed by Cobalt Oxide Supported on Ti₂AlC MAX Phase

Contact Info

Product

Resources

About

Phase stability and initial low-temperature oxidation mechanism of Ti2AlC thin films

Cited by 47 publications

References 50 publications

Contribution of core-loss fine structures to the characterization of ion irradiation damages in the nanolaminated ceramic Ti3AlC2

Contribution of core-loss fine structures to the characterization of ion irradiation damages in the nanolaminated ceramic Ti3AlC2

Phase Formation of Nanolaminated Transition Metal Carbide Thin Films

Butane Dry Reforming Catalyzed by Cobalt Oxide Supported on Ti2AlC MAX Phase

Contact Info

Product

Resources

About

Butane Dry Reforming Catalyzed by Cobalt Oxide Supported on Ti₂AlC MAX Phase