Shrinkage of Hollow Nanoparticles of Oxides of Cu and Ni at High Temperatures

Ryusuke Nakamura; Hideo Nakajima; Hirotaro Mori

doi:10.4028/www.scientific.net/DDF.289-292.673

Paper Titles

Grain Boundary Diffusion in Recrystallizing Nanocrystalline Materials
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Formation of a Nano-Hole via Oxidation of Metal Nanoparticles
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Surface-Sandwich Segregation Phenomena in Bimetallic Ag-Ni and Pd-Ni Nanoparticles: A Molecular Dynamics Study
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Composition Effect on Shrinkage of Hollow Binary Alloy Nanospheres
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Shrinkage of Hollow Nanoparticles of Oxides of Cu and Ni at High Temperatures
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Essay on Techniques & Physics of Some Diffusion-Controlled Processes in Materials: Relevance to Nanofabrication Applications
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Impact of Carbon on the Diffusion of Donor Atoms in Germanium
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Diffusion in Isotope Heterostructures Investigated by Neutron Reflectometry
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Atomic Diffusion and its Relation to Thermodynamic Forces in Al-Ni Melts
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Shrinkage of Hollow Nanoparticles of Oxides of Cu and Ni at High Temperatures

Abstract:

The structural stability of hollow Cu2O and NiO nanoparticles, which were obtained via oxidation of Cu and Ni nanoparticles in air, was studied by transmission electron microscopy (TEM). Hollow Cu2O and NiO were observed to have shrunk at 473 and 623 K in annealing under 5.0×10-5 Pa, respectively, where the reduction reactions from oxides to metals started. As a result of shrinking associated with reduction, hollow oxides turned into solid metal nanoparticles after annealing at higher temperatures for a long time. In addition, hollow oxides shrunk and collapsed through high-temperature oxidation. It was found that shrinking of hollow oxides during oxidation occurs at temperature where the diffusion coefficients of slower diffusing species reach around 10-22 m2s-1. It seems that the hollow oxide nanoparticles tend to shrink and collapse at high temperatures because the hollow structures are energetically unstable.