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Báo cáo hóa học: "Nearly Monodispersion CoSm Alloy Nanoparticles Formed by an In-situ Rapid Cooling and Passivating Microfluidic Process"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Research Nearly Monodispersion CoSm Alloy Nanoparticles Formed by an In-situ Rapid Cooling and Passivating Microfluidic Process | Nanoscale Res Lett 2009 4 1130-1134 DOI 10.1007 S11671-009-9369-8 NANO EXPRESS Nearly Monodispersion CoSm Alloy Nanoparticles Formed by an In-situ Rapid Cooling and Passivating Microfluidic Process Yujun Song Laurence L. Henry Received 25 March 2009 Accepted 28 May 2009 Published online to the authors 2009 Abstract An in situ rapid cooling and passivating microfluidic process has been developed for the synthesis of nearly monodispersed cobalt samarium nanoparticles NPs with tunable crystal structures and surface properties. This process involves promoting the nucleation and growth of NPs at an elevated temperature and rapidly quenching the NP colloids in a solution containing a passivating reagent at a reduced temperature. We have shown that Cobalt samarium NPs having amorphous crystal structures and a thin passivating layer can be synthesized with uniform nonspherical shapes and size of about 4.8 nm. The amorphous CoSm NPs in our study have blocking temperature near 40 K and average coercivity of 225 Oe at 10 K. The NPs also exhibit high anisotropic magnetic properties with a wasp-waist hysteresis loop and a bias shift of coercivity due to the shape anisotropy and the exchange coupling between the core and the thin oxidized surface layer. Keywords Nanoparticles Microfluidic reactor Synthesis Monodispersion Alloy Cobalt Samarium Over the years microfluidic reactor MR processes have gained much attention in the preparation of specific materials due to its in situ spatial and temporal control of Y. Song H Key Laboratory of Aerospace Materials and Performance Ministry of Education School of Materials Science and Engineering Beihang University 100191 Beijing China e-mail yjsong2007@gmail.com songyj@buaa.edu.cn L. L. Henry Department of Physics Southern University A M College Baton Rouge LA 70813 USA 14 June 2009 reaction kinetics in addition to efficient mass and heat transfer 1-5 . Recently application of microfluidic reactors has been expanded from the improvement of