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Visualizing the iron atom exchange front in the Fe(II)-catalyzed recrystallization of goethite by atom probe tomography
- Source :
- Proceedings of the National Academy of Sciences of the United States of America. 116(8)
- Publication Year :
- 2019
-
Abstract
- 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.
- Subjects :
- Oxide minerals
Multidisciplinary
Goethite
Materials science
Iron oxide
Recrystallization (metallurgy)
02 engineering and technology
Atom probe
010501 environmental sciences
Hematite
021001 nanoscience & nanotechnology
01 natural sciences
Corrections
law.invention
Electron transfer
chemistry.chemical_compound
chemistry
law
Chemical physics
visual_art
visual_art.visual_art_medium
Crystallite
0210 nano-technology
0105 earth and related environmental sciences
Subjects
Details
- ISSN :
- 10916490
- Volume :
- 116
- Issue :
- 8
- Database :
- OpenAIRE
- Journal :
- Proceedings of the National Academy of Sciences of the United States of America
- Accession number :
- edsair.doi.dedup.....5acd97514e892718c19a1eabcd6b8c71