Journal
SURFACE SCIENCE
Volume 609, Issue -, Pages 161-166Publisher
ELSEVIER SCIENCE BV
DOI: 10.1016/j.susc.2012.12.001
Keywords
Interface; Epitaxial growth; Strain-release mechanisms; Coreshell nanoparticles; Scanning transmission electron microscopy
Categories
Funding
- National Center for Research Resources [5 G12RR013646-12]
- National Institute on Minority Health and Health Disparities from the National Institutes of Health [G12MD007591]
- NSF [DMR-1103730]
- PREM: NSF PREM [DMR 0934218]
- Direct For Mathematical & Physical Scien
- Division Of Materials Research [934218, 1103730] Funding Source: National Science Foundation
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Lattice mismatch in a bimetallic core-shell nanoparticle will cause strain in the epitaxial shell layer, and if it reaches the critical layer thickness misfit dislocations will appear in order to release the increasing strain. These defects are relevant since they will directly impact the atomic and electronic structures thereby changing the physical and chemical properties of the nanoparticles. Here we report the direct observation and evolution through aberration-corrected scanning transmission electron microscopy of dislocations in AuPd core-shell nanoparticles. Our results show that first Shockley partial dislocations (SPD) combined with stacking faults (SF) appear at the last Pd layer; then, as the shell grows the SPDs and SFs appear at the interface and combine with misfit dislocations, which finally diffuse to the free surfaces due to the alloying of Au into the Pd shell. The critical layer thickness was found to be at least 50% greater than in thin films, confirming that shell growth on nanoparticles can sustain more strain due to the tridimensional nature of the nanoparticles. (C) 2012 Elsevier B.V. All rights reserved.
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