Tuyển tập các báo cáo nghiên cứu về hóa học được đăng trên tạp chí hóa hoc quốc tế đề tài : Co nanoparticle hybridization with singlecrystalline Bi nanowires | Noh et al. Nanoscale Research Letters 2011 6 598 http content 6 1 598 o Nanoscale Research Letters a SpringerOpen Journal NANO EXPRESS Open Access Co nanoparticle hybridization with singlecrystalline Bi nanowires Jin-Seo Noh1 Min-Kyung Lee1 Jinhee Ham and Wooyoung Lee 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. 1. Introduction Magnetic nanoparticles have unique size effects that may provide insights into potential applications in various fields such as ultra-high density information storage color imaging bioprocessing and ferrofluids 1-3 . Specifically cobalt Co nanoparticles have been a subject of intensive research because of its high magnetocrystalline anisotropy 7 X 106 erg cm3 and large estimated critical size for single domains approx. 70 nm 4 . To synthesize Co nanoparticles with a controlled size and size distribution various techniques have been utilized including evaporation in an inert gas 5 chemical vapor condensation by either heating or laser-irradiating Co2 CO 8 precursor 6 7 and solution phase reduction of CoCl2 in stabilizing agents
