Ion irradiation effects on metallic nanocrystals
Date
2007
Authors
Kluth, Patrick
Johannessen, Bernt
Giulian, Raquel
Schnohr, Claudia
Foran, Garry J
Cookson, D J
Byrne, Aidan
Ridgway, Mark C
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Gordon and Breach
Abstract
We have investigated structural and morphological properties of metallic nanocrystals (NCs) exposed to ion irradiation. NCs were characterized by transmission electron microscopy in combination with advanced synchrotron-based analytical techniques, in particular X-ray absorption spectroscopy and small-angle X-ray scattering. A number of different effects were observed depending on the irradiation conditions. At energies where nuclear stopping is predominant, structural disorder/amorphization followed by inverse Ostwald ripening/dissolution due to ion beam mixing was observed for Au and Cu NCs embedded in SiO2. The ion-irradiation-induced crystalline to amorphous transition in the NCs, which cannot be achieved in the corresponding bulk metals, was attributed to their initially higher structural energy as compared to bulk material and possibly preferential nucleation of the amorphous phase at the NC/SiO2 interface. At very high irradiation energies (swift heavy ion irradiation), where the energy loss is nearly entirely due to electronic stopping, a size-dependent shape transformation of the NCs from spheres to rod like shapes was apparent in Au NCs. Our preliminary results are in good agreement with considerations on melting of the NCs in the ion track as one mechanism involved in the shape transformation.
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Keywords: Amorphization; Extended X ray absorption fine structure spectroscopy; Heavy ions; Ion bombardment; Nucleation; Transmission electron microscopy; X ray scattering; Amorphous transition; Metallic nanocrystals; Shape transformation; Nanocrystals EXAFS; Ion irradiation; Nanocrystals; SAXS; Swift heavy ions
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Radiation Effects and Defects in Solids
Type
Journal article
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2037-12-31
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