Passivation-driven speciation, dealloying and purification
- Iowa State Univ., Ames, IA (United States)
- Iowa State Univ., Ames, IA (United States); Micro-Electronics Research Center, Ames, IA (United States)
Thin passivating surface oxide layers on metal alloys form a dissipation horizon between dissimilar phases, hence harbour an inherent free energy and composition gradient. We exploit this gradient to drive order and selective surface separation (speciation), enabling redox-driven enrichment of the core by selective conversion of low standard reduction potential (E°) components into oxides. Additionally, coupling this oxide growth to volumetric changes during solidification allows us to create oxide crystallites trapped in a metal (‘ship-in-a-bottle’) or extrusion of metal fingerlings on the heavily oxidized particle. We confirm the underlying mechanism through high temperature X-ray diffraction and characterization of solidification-trapped particle states. We demonstrate that engineering the passivating surface oxide can lead to purification via selective dealloying with concomitant enrichment of the core, leading to disparate particle morphologies.
- Research Organization:
- Sep-All LLC, Ames, IA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- Grant/Contract Number:
- SC0018791; DMR-1626315; SBIR DE-SC0018791
- OSTI ID:
- 1852685
- Alternate ID(s):
- OSTI ID: 1762545
- Journal Information:
- Materials Horizons, Vol. 8, Issue 3; ISSN 2051-6347
- Publisher:
- Royal Society of ChemistryCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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