Open Access Nano Express

Co nanoparticle hybridization with single-crystalline Bi nanowires

Jin-Seo Noh, Min-Kyung Lee, Jinhee Ham and Wooyoung Lee*

Author Affiliations

Department of Materials Science and Engineering, Yonsei University, Seoul 120-749, Korea

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Nanoscale Research Letters 2011, 6:598  doi:10.1186/1556-276X-6-598

Published: 21 November 2011

Abstract

Crystalline Co nanoparticles were hybridized with single-crystalline Bi nanowires simply by annealing Co-coated Bi nanowires at elevated temperatures. An initially near-amorphous Co film of 2-7 nm in thickness began to disrupt its morphology and to be locally transformed into crystallites in the early stage of annealing. The Co film became discontinuous after prolonged annealing, finally leading to isolated, crystalline Co nanoparticles of 8-27 nm in size. This process spontaneously proceeds to reduce the high surface tension and total energy of Co film. The annealing time required for Co nanoparticle formation decreased as annealing temperature increased, reflecting that this transformation occurs by the diffusional flow of Co atoms. The Co nanoparticle formation process was explained by a hole agglomeration and growth mechanism, which is similar to the model suggested by Brandon and Bradshaw, followed by the nanoparticle refinement.