An integrated high temperature environmental cell for atom probe tomography studies of gas-surface reactions: Instrumentation and results

Dumpala, Santoshrupa; Broderick, Scott; Bagot, P.A.J.; Rajan, Krishna

doi:10.1016/j.ultramic.2014.03.002

Cited by 18 publications

(20 citation statements)

References 52 publications

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“…In parallel, recent progress in operating at pressures up to 1 bar (10 5 Pa) has been achieved. Figure 3 shows details of preliminary experiments using the cell developed by Dumpala et al 36 These examples demonstrate that it is possible to distinguish between differences in oxidation levels down to the nanoscale for brief oxygen exposures in Al and Pt alloys; the aluminum sample revealed a relatively thicker (Al 2 O 3 ) layer compared with the Rh-rich oxide on Pt-Rh-Ir, in agreement with known thermodynamics. These initial stages of reaction between gases and the alloy surface are poorly understood at present, despite their importance in catalysis and corrosion protection.…”

Section: In Situ Reaction Cellsmentioning

confidence: 60%

“…A detailed schematic of one of the forerunners and how it is incorporated into the atom probe vacuum system is presented in Figure 2 . 36 Current developments are focused on increasing heat transfer to the sample tip in order to extend operating temperatures, widening the relevance of cells to materials science. In parallel, recent progress in operating at pressures up to 1 bar (10 5 Pa) has been achieved.…”

Section: In Situ Reaction Cellsmentioning

confidence: 99%

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Advances in atom probe tomography instrumentation: Implications for materials research

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Section: In Situ Reaction Cellsmentioning

confidence: 60%

Section: In Situ Reaction Cellsmentioning

confidence: 99%

Advances in atom probe tomography instrumentation: Implications for materials research

et al. 2016

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“…Reactions cells designed for 3DAP systems can expose specimens to gas pressures up to 1 bar and at temperatures up to 873 K [85]; for modern versions of the instrument, cells exist with operating conditions of a few tens of mbar and up to T ≈ 723 K [86], and from 10 −6 to 1000 mbar and up to T ≈ 723 K with cryogenic quenching capabilities for the most recent design [87]. The improvement of APT analysis due to the use of in situ reaction cells is presented in Figure 3, corresponding to the analysis of Al oxidation under the same reaction conditions, but performed in ex situ (top spectra) and in situ (bottom spectra) cells [86]. Experiments performed in the ex situ cell reveal the presence of additional unassigned peaks in the mass spectra, probably originating in contamination during the transfer from the cell to the LEAP.…”

Section: Latest Developments: Environmental Cells For Aptmentioning

confidence: 99%

“…Different systems have been studied with these cells: NO and CO/Pt, NO, CO, O 2 , N 2 O, NO + CO and NO + O 2 /Pt-Rh [85,88,89], NO/Pt-Rh-Ir, NO/Pt-Rh-Ru [90], NO/Au-Pd [52,91] and O 2 , N 2 O and H 2 /Au-Ag [92] for the 3DAP version of the cell; and O 2 /Al, O 2 /Pt-Ir, O 2 /Pt-Rh-Ir [86]; D 2 /Pd, O 2 and H 2 O/Mg [87] for the most recent cells.…”

Section: Latest Developments: Environmental Cells For Aptmentioning

confidence: 99%

Atom Probe Tomography for Catalysis Applications: A Review

2019

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Atom probe tomography is a well-established analytical instrument for imaging the 3D structure and composition of materials with high mass resolution, sub-nanometer spatial resolution and ppm elemental sensitivity. Thanks to recent hardware developments in Atom Probe Tomography (APT), combined with progress on site-specific focused ion beam (FIB)-based sample preparation methods and improved data treatment software, complex materials can now be routinely investigated. From model samples to complex, usable porous structures, there is currently a growing interest in the analysis of catalytic materials. APT is able to probe the end state of atomic-scale processes, providing information needed to improve the synthesis of catalysts and to unravel structure/composition/reactivity relationships. This review focuses on the study of catalytic materials with increasing complexity (tip-sample, unsupported and supported nanoparticles, powders, self-supported catalysts and zeolites), as well as sample preparation methods developed to obtain suitable specimens for APT experiments.

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confidence: 99%

Tracking Structural Modifications from In-Situ Atom Probe Gas-Solid Reactions through Computational Homology

2017

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We have developed an in-situ reaction chamber for atom probe tomography (APT) to experimentally measure in-situ gas-surface reactions as a function of time, temperature, and pressure [1]. We are able to look at a very broad range of gases and reactions and the ability to perform these measurements allows us to accurately perform calculations for a wider range of environments and providing a wider range of values for calibrating atom probe reconstructions and subsequent electronic structure modeling [2]. Therefore, combining this in situ atomistic measurement capability for surface reactions with computational protocols allows us to computationally address the issues related with surface degradation under extreme environments.With the use of the in-situ chamber (Figure 1), we can measure the changes at the surface in terms of neighborhood chemistry and relative bond strengths. These surface-chemistry relationships have been compared and subsequently calibrated with electronic structure calculations to assess the degradation mechanisms [3][4]. This approach allows to identify the mechanism for degradation in terms of charge distribution, model the relative bond strengths, and measure the evaporation field (ie. the propensity to degrade) as a function of applied field, surface chemistry, and surface structure. When coupled with experimental measurements of the ingress of gases (Figure 2), a full understanding of the connection between degradation, surface reactivity, microstructural effects, and diffusion is developed. Further, this can be linked with ion evaporation maps to define how the atoms evaporate from the surface, whether as a single ion or as a bonded species. The statistics associated with the evaporation maps can be tracked back to the surface bonding, where atoms more likely to evaporate as a bonded species have stronger relative bond strengths. These computational platforms allow for enhanced understanding of the role of gas and material chemistry on the degradation of a material under extreme conditions. However, the issue we explore here is that the assessment of crystal structure and the corresponding structural effects are not easily described in this process. For this reason, persistence diagrams will be developed that describe the structure through packing density and relative spatial positioning, with the specific 3D homological features defined. In this way, persistence diagrams are defined and correlated with relative atom sizes and nearest neighbor environments. By tracking these changes over an entire APT experiment, we can define the relative changes in the structure, describe the data systematics, and integrate a structural measurement component into the modeling framework previously described. This therefore expands our understanding of degradation and surface-gas reactions to chemistry-processinglocal structure relationships [5].

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An integrated high temperature environmental cell for atom probe tomography studies of gas-surface reactions: Instrumentation and results

Cited by 18 publications

References 52 publications

Advances in atom probe tomography instrumentation: Implications for materials research

Advances in atom probe tomography instrumentation: Implications for materials research

Atom Probe Tomography for Catalysis Applications: A Review

Tracking Structural Modifications from In-Situ Atom Probe Gas-Solid Reactions through Computational Homology

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