Characterization and Spatial Mapping of Crystal Lattice Strain in Nanoporous Gold
Notice bibliographique
Résumé
There is a growing interest in nanoporous gold (NPG) as a promising material for next generation biosensors, actuators, and catalysts. Formed by scalable top-down methods, the dealloying of AgAu precursors yields a mechanically stable, noble metal nanostructure with active mass-specific surface areas on the order of several m2/g. This property is readily exploited for the abundance of binding sites in many useful applications. Throughout the porous layer, the predominance of surface atoms relative to the master alloy, coupled with the local curvature at the solid-pore interface, changes the strain state of the material to a large extent. The strain alters the macroscopic deformation of the material and is impacted by the adsorption and desorption of reactants. Understanding and harnessing these strain effects are pivotal in advancing the design and optimization of NPG-based functional materials for enhanced efficiency and sensitivity in diverse applications. However, despite the significant progress in understanding surface-induced strains in NPG, the variations in strain distribution from the surface to the dealloying front remain relatively unexplored. Investigating these differences is crucial for comprehension of the material's mechanical behavior, as it can provide insights into the dynamic evolution of strain during dealloying processes. Moreover, incorporation of small amounts of Pt to the master alloy, yielding NPG-Pt, fundamentally alters the structure evolution during dealloying and high temperature coarsening. The Pt-rich surfaces that result from these processes introduce a potential additional layer of complexity to the strain dynamics within the material, though this effect has not yet been explored. This work aims at unravelling the intricacies of strain distribution in NPG, especially in the context of NPG-Pt, using advanced electron microscopy. Among the techniques used for nanoscale strain resolution, four-dimensional scanning transmission electron microscopy (4D-STEM) stands out for its ability to quantify and spatially resolve lattice strain at varying magnifications. 4D-STEM was used to map strain at multiple length scales; spanning the entire nanoporous layer and at the level of individual NPG/NPG-Pt ligaments. Given the sensitivity of the method to optical distortions in the image data, another emphasis of this work was the optimization of microscope parameters and data processing to yield reliable 4D-STEM datasets. Resulting maps of lattice deformation reveal how the strain evolves in parallel with the microstructure during prolonged dealloying times. Additionally, high-magnification mapping of coarsened ligaments shows the retention of strain despite significantly reduced surface area. These findings may be used to carefully engineer strain in nanoporous metals by controlling the dealloying process, and harness bulk strain for stress-driven sensors and actuators.
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Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,001 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,001 | 0,001 |
| Méta-épidémiologie (sens large) | 0,001 | 0,000 |
| Bibliométrie | 0,000 | 0,001 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,001 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».