Dislocation nucleation at nanoscale fluid inclusions: Direct observation from atom probe tomography data of naturally deformed pyrite
Notice bibliographique
Résumé
<p>In recent years, increasing developments in microscopy and microanalysis have allowed for the direct observation of nanoscale crystalline defects (i.e. dislocations). These defects are particularly important in naturally deformed materials yet this avenue of research remains understudied within the Earth Sciences. Dislocations can now be documented through the use of new and innovative structural and chemical analytical techniques such as electron channeling contrast imaging (ECCI), transmission electron microscopy, and atom probe tomography (APT). The presence and migration of dislocations in crystalline materials, including their role in trace element mobility, play a vital function in the way these materials respond to an applied stress. However, the mechanisms by which dislocations nucleate in minerals remain poorly understood. Prevailing models for dislocation nucleation include generation by Frank-Read sources, stress localization at crack-tips, atomic segregation, and free surface nucleation by critical stress-gradient criterion. Based on recent APT data from naturally-deformed pyrite, combined with electron backscatter diffraction (EBSD) mapping and ECC imaging, we propose a new nucleation mechanism where dislocations are generated by the local stress field in the vicinity of fluid inclusions. The investigated sample consists of a polycrystalline pyrite aggregate within a black shale host rock that has witnessed a peak temperature of 300°C. The combined EBSD and ECCI results reveal crystal plasticity in the form of lattice misorientation up to 8.5° and low-angle grain boundary development. APT data reveals nanoscale fluid inclusions enriched in As, O (H<sub>2</sub>O), Na and K as well as As- and Co-rich dislocations linked by fluid inclusions. This new model is the first documentation with APT methods of fluid inclusions (voids) in minerals, nanoscale features that are commonly misinterpreted as element clusters or chemically-enriched crystal-defects. The combined data has significant trans-disciplinary implications to the geosciences (structural geology, geochemistry, economic geology, geochronology), the material sciences (metals, ceramics, polymers), and analytical microscopy. Within geochronology voids and dislocations such as these in dated minerals may host elements or isotopes that negatively affect their age. Within ore deposit geology, voids in precious metal-hosting minerals may act as the necessary traps to structurally prevent the metals (gold, silver, copper) from migrating or diffusing out of the host mineral. In material sciences, the presence of such crystalline features can either limit or enhance the performance of engineering materials. Thus, performing APT analysis on crystalline material can help us better understand and predict their physical properties.</p>
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
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 | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,001 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 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 ».