Dependence of magnetic properties on crystallite size of CoFe₂O₄ nanoparticles synthesised by auto-combustion method

Abstract

Cobalt ferrite (CoFe₂O₄) nanoparticles were prepared through an auto-combustion method. The results of XRD show that the crystallite size of CoFe₂O₄ nanoparticles increases from 57 to 105 nm with a slight change in lattice constant as the annealing temperature increases from 300 to 1200°C. The magnetic measurements by vibrating sample magnetometer (VSM) show that M _s increases monotonously by increasing the annealing temperature from 300 to 1200°C and C _hB and M _s reached a maximum when annealing temperature is about 400°C due to the change of the grain size.

Keywords:

• nanoparticle
• cobalt ferrite (CoFe2O4)
• auto-combustion
• anneal
• magnetic properties

Acknowledgements

The authors would like to thank Z.Y. Kuang and Z. Li of Huazhong University of Science and Technology for their help with the magnetic measurements. This work is supported by the Chinese National Foundation of Natural Science (No. 10674105), National Basic Research Program of China (2007CB607501) and a financed program of Provincial Key Laboratory of Organic Polymer Optoelectronic Materials, Hubei, China.