Tuneable magnetic properties of hydrothermally synthesised core/shell CoFe2O4/NiFe2O4 and NiFe2O4/CoFe2O4 nanoparticles

Almeida, T. P. , Moro, F., Fay, M. W., Zhu, Y. and Brown, P. D. (2014) Tuneable magnetic properties of hydrothermally synthesised core/shell CoFe2O4/NiFe2O4 and NiFe2O4/CoFe2O4 nanoparticles. Journal of Nanoparticle Research, 16, 2395. (doi: 10.1007/s11051-014-2395-1)

Abstract

Core/shell hetero-nanostructures of hydrothermally synthesised cobalt and nickel ferrites are shown to exhibit novel magnetic properties. The compositions and phase distributions of homogeneous Co0.5Ni0.5Fe2O4, and core/shell NiFe2O4-Core/CoFe2O4-Shell and CoFe2O4-Core/NiFe2O4-Shell nanoparticles (NPs) are confirmed using high-resolution transmission electron microscopy and electron energy loss spectroscopy. SQUID magnetometry investigations demonstrate that, at room temperature, homogeneous Co0.5Ni0.5Fe2O4 NPs (~8 nm in diameter) are in the super-paramagnetic state, the magnetisation of NiFe2O4-Core/CoFe2O4-Shell NPs (~11 nm in diameter) is partially blocked, whilst CoFe2O4-Core/NiFe2O4-Shell NPs (~11 nm in diameter) are in a blocked state. In particular, NiFe2O4-Core/CoFe2O4-Shell NPs exhibit twice the out-of-phase χ″ susceptibility of CoFe2O4-Core/NiFe2O4-Shell NPs, being dominated by the magnetisation of the core ferrite phase. Hence, when exposed to a high-frequency magnetic field, it is considered that the high χ″ susceptibility of NiFe2O4-Core/CoFe2O4-Shell NPs will promote large magnetically induced heating effects, making these core/shell NPs strong candidates for hyperthermia applications.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Almeida, Dr Trevor
• Authors: Almeida, T. P., Moro, F., Fay, M. W., Zhu, Y., and Brown, P. D.
• College/School: College of Science and Engineering > School of Physics and Astronomy
• Journal Name: Journal of Nanoparticle Research
• Publisher: Springer
• ISSN: 1388-0764
• ISSN (Online): 1572-896X