| DOI | Resolve DOI: https://doi.org/10.1002/cctc.201500380 |
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| Author | Search for: Prabhudev, Sagar; Search for: Bugnet, Matthieu; Search for: Zhu, Guo-Zhen; Search for: Bock, Christina1; Search for: Botton, Gianluigi A. |
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| Affiliation | - National Research Council of Canada. Energy, Mining and Environment
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| Format | Text, Article |
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| Subject | Annealing; Characterization; Electrocatalysis; Electron energy levels; Electron energy loss spectroscopy; Electron microscopes; Electron microscopy; Electron scattering; Energy dissipation; Fuel cells; Fuel storage; Image reconstruction; Iron; Nanoparticles; Phase transitions; Platinum; Platinum alloys; Segregation (metallography); Alloy nanoparticle; Atomic-resolution imaging; In-situ electron microscopy; Microscopy technique; Order transformation; Segregation phenomena; Single nanoparticle; Ultrahigh density information storage; Surface segregation |
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| Abstract | Coupling electron microscopy techniques with insitu heating ability allows us to study phase transformations on the single-nanoparticle level. We exploit this setup to study disorder-to-order transformation of Pt-Fe alloy nanoparticles, a material that is of great interest to fuel-cell electrocatalysis and ultrahigh density information storage. In contrast to earlier reports, we show that Fe (instead of Pt) segregates towards the particle surface during annealing and forms a Fe-rich FeOx outer shell over the alloy core. By combining both exsitu and insitu approaches to probe the interplay between ordering and surface-segregation phenomena, we illustrate that the surface segregation of Fe precedes the ordering process and affects the ordered phase evolution dramatically. We show that the ordering initiates preferably at the pre-existent Fe-rich shell than the particle core. While the material-specific findings from this study open interesting perspectives towards a controlled phase evolution of Pt-Fe nanoalloys, the characterization methodologies described are general and should prove useful to probing a wide-range of nanomaterials. Surface-segregation vs atomic-ordering: By using atomic-resolution imaging and electron energy loss spectroscopy and employing both exsitu and insitu approaches, an ongoing interplay between segregation and ordering during the thermal annealing of Pt - Fe alloy nanoparticles is studied. Findings reveal a surface segregation of Fe that is in contrast to earlier reports suggesting Pt surface segregation. |
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| Publication date | 2015-11-16 |
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| In | |
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| Language | English |
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| Peer reviewed | Yes |
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| NPARC number | 21277392 |
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| Export citation | Export as RIS |
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| Report a correction | Report a correction (opens in a new tab) |
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| Record identifier | 409aa1e8-f48b-4eee-a556-bfe53714d340 |
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| Record created | 2016-03-09 |
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| Record modified | 2020-04-22 |
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