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PREVENTION OF SINTERING DURING ANNEALING PROCESS OF FePt NANOPARTICLES COATED WITH ZnO SHELL
HOSSEIN ZEYNALI,HOSSEIN AKBARI,S. ARUMUGAM,ZOHREH CHAMANZADEH,G. KALAISELVAN,REYHANEH KARIMI GHASABEH 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2012 NANO Vol.7 No.6
Monodispersed 4.1 nm FePt nanoparticles with narrow size distribution were successfully synthesized by the chemical polyol process with co-reduction of Fe(acac)3 and Pt(acac)2 in the presence of 1,2-hexadecanediol as a reducing agent. To achieve hard ferromagnetic behavior with L10 phase and face center tetragonal (fct) structure, high temperature annealing is performed. Annealing causes the surfactant surrounding particles to decompose and agglomeration of particles occurs. In the present work, chemically synthesized FePt nanoparticles were coated with nonmagnetic ZnO oxide shell to prevent them from sintering. Coercivity of FePt and FePt/ZnO nanoparticles increases from 5 kOe to 10 kOe and 1.8 kOe to 6 kOe respectively, with the increasing annealing temperatures from 650 to 750?C.
HOSSEIN ZEYNALI,HOSSEIN AKBARI,S. ARUMUGAM 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.23 No.-
Monodisperse 4.11 nm FePt nanoparticles were synthesized via chemical co-reduction of iron (III) acetylacetonate and platinum (II) acetylacetonate by 1,2-hexadecanediol as a reducing agent. Then through the seed mediated growth process smaller sized FePt nanoparticles are used as seeds for the growth of larger sized particles. There is no specific limitation to achieve upper size range by this method. In this work, we have successfully synthesized FePt nanoparticles up to 8.32 nm. After annealing these particles become ferromagnetic and their coercivirty increases with increasing particle sizes and reaches a maximum value of 17760 Oe for size of 8.32 nm.