Enhanced analysis of nanoporous gold by atom probe tomography

El‐Zoka, Ayman A.; Langelier, Brian; Botton, Gianluigi A.; Newman, R.C.

doi:10.1016/j.matchar.2017.03.013

Cited by 40 publications

(34 citation statements)

References 33 publications

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“…Although challenging, APT analysis of the distribution of potassium on amorphous ferrihydrite particles was previously achieved (31). In particular, nanoparticles must be embedded in a matrix without nanovoids or microvoids, which can cause premature fracture or artifacts in APT reconstructions, that preserves their structure and composition to acquire meaningful data that can be related to the original particles (32,51,52). Tedious but essential work entails refining and testing specimen preparation techniques, such as embedding in a material compatible with field ionization of the particles that is free of voids, strongly adhered, and free of noninterfering ions.…”

Section: Discussionmentioning

confidence: 99%

Visualizing the iron atom exchange front in the Fe(II)-catalyzed recrystallization of goethite by atom probe tomography

Taylor

Liu

Zhang

et al. 2019

Proc. Natl. Acad. Sci. U.S.A.

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The autocatalytic redox interaction between aqueous Fe(II) and Fe(III)-(oxyhydr)oxide minerals such as goethite and hematite leads to rapid recrystallization marked, in principle, by an atom exchange (AE) front, according to bulk iron isotopic tracer studies. However, direct evidence for this AE front has been elusive given the analytical challenges of mass-resolved imaging at the nanoscale on individual crystallites. We report successful isolation and characterization of the AE front in goethite microrods by 3D atom probe tomography (APT). The microrods were reacted with Fe(II) enriched in tracer 57Fe at conditions consistent with prior bulk studies. APT analyses and 3D reconstructions on cross-sections of the microrods reveal an AE front that is spatially heterogeneous, at times penetrating several nanometers into the lattice, in a manner consistent with defect-accelerated exchange. Evidence for exchange along microstructural domain boundaries was also found, suggesting another important link between exchange extent and initial defect content. The findings provide an unprecedented view into the spatial and temporal characteristics of Fe(II)-catalyzed recrystallization at the atomic scale, and substantiate speculation regarding the role of defects controlling the dynamics of electron transfer and AE interaction at this important redox interface.

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Section: Discussionmentioning

confidence: 99%

Visualizing the iron atom exchange front in the Fe(II)-catalyzed recrystallization of goethite by atom probe tomography

Taylor

Liu

Zhang

et al. 2019

Proc. Natl. Acad. Sci. U.S.A.

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“…The second set of experiments uses an alternative procedure to fill the pores by electrodeposition [175,176]. Electrodeposition of metals on a porous structure can lead to incomplete filling, clustered deposition and inhomogeneous filling [177][178][179].…”

Section: Catalysts As Porous Materials-nanoporous Aumentioning

confidence: 99%

“…Further work proved that Pt-based precursor as a filling material allows for npAu analysis by APT in laser pulse mode [173][174], emphasizing the importance of acquisition parameters. The second set of experiments uses an alternative procedure to fill the pores by electrodeposition [175,176]. Electrodeposition of metals on a porous structure can lead to incomplete filling, clustered deposition and inhomogeneous filling [177][178][179].…”

Section: Catalysts As Porous Materials-nanoporous Aumentioning

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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“…Many pioneering studies concerning this topic [1][2][3][4][5][13][14][15][16][17][18] have been conducted by now, and one critical step is to reconstruct a proper microstructure model of the porous materials. A straightforward way is adopting a commercial package, say Minics or others, to reproduce the true microstructures of porous materials at a specific scale by using the tomographic images generated by the atom-probe tomography [19], electron microscopy [20], X-ray tomography [21], or focused-ion-beam-nonatomography [22]. To be noted, the methods of this kind need a huge number of tomographic images of all directions and different scales so as to construct an accurate description of the porous materials [23] due to the random distribution of pores and their shapes and size variations.…”

Section: Introductionmentioning

confidence: 99%

Finite Element Modeling of Porous Microstructures With Random Holes of Different-Shapes and -Sizes to Predict Their Effective Elastic Behavior

Dong

Liu

et al. 2019

Applied Sciences

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Porous materials are promising media for designing medical instruments, drug carriers, and bioimplants because of their excellent biocompatibility, ease of design, and large variation of elastic moduli. In this study, a computational strategy using the finite element method is developed to model the porous microstructures and to predict the relevant elastic moduli considering the actual characteristics of the micropores and their distributions. First, an element-based approach is presented to generate pores of different shapes and sizes according to the experimental observations. Then, a computational scheme to evaluate the effective moduli of macroscopically isotropic porous materials based on their micro-mechanics is introduced. Next, the accuracy of our approach is verified with the analytical solutions of the extreme bounds of the elastic isotropic moduli of a simplified model and with the experimental data available in the literature. Finally, the influence of the shape of pores and their distribution modes are assessed.

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Enhanced analysis of nanoporous gold by atom probe tomography

Cited by 40 publications

References 33 publications

Visualizing the iron atom exchange front in the Fe(II)-catalyzed recrystallization of goethite by atom probe tomography

Visualizing the iron atom exchange front in the Fe(II)-catalyzed recrystallization of goethite by atom probe tomography

Atom Probe Tomography for Catalysis Applications: A Review

Finite Element Modeling of Porous Microstructures With Random Holes of Different-Shapes and -Sizes to Predict Their Effective Elastic Behavior

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