Research Paper

Journal of Nanoparticle Research

, Volume 13, Issue 1, pp 213-220

Magnetite hollow spheres: solution synthesis, phase formation and magnetic property

  • Qian SunAffiliated withKey Laboratory of Micro-Nano Measurement-Manipulation and Physics (Ministry of Education), Department of Physics, Beijing University of Aeronautics and Astronautics
  • , Zheng RenAffiliated withKey Laboratory of Micro-Nano Measurement-Manipulation and Physics (Ministry of Education), Department of Physics, Beijing University of Aeronautics and Astronautics
  • , Rongming WangAffiliated withKey Laboratory of Micro-Nano Measurement-Manipulation and Physics (Ministry of Education), Department of Physics, Beijing University of Aeronautics and Astronautics Email author 
  • , Weimeng ChenAffiliated withDepartment of Physics, Peking University
  • , Chinping ChenAffiliated withDepartment of Physics, Peking University Email author 

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Abstract

Polycrystalline magnetite hollow spheres with diameter of about 200 nm and shell thickness of 30–60 nm were prepared via a facile solution route. For the reaction, ethylene glycol (EG) served as the reducing agent and soldium acetate played the role of precipitator. In addition, polyvinylpyrrolidone (PVP) served as a surface stabilizer. The morphologies and structures were characterized by scanning electron microscopy, transmission electron microscopy and X-ray diffraction. The intermediate products at different stages were also studied to shed light on the evolution of phase formation. It revealed that the hollow structure formed via self-assembly of nanocrystallites (about 15 nm) using sodium acetate as mild precipitator. Evidences further pointed out that the Ostwald ripening process well explained the growth mechanism of the hollow structure. Magnetization measurements showed that the coercivity of magnetite hollow spheres at low temperature is about 200 Oe and the saturation magnetization is about 83 emu g−1, roughly 85% that of the bulk phase, close to the value of its solid counterpart. In addition, a freezing transition was observed at 25 K.

Keywords

Magnetite hollow spheres Phase formation Magnetic property