Synthesis, structure and magnetic properties of multipod-shaped cobalt ferrite nanocrystals

We applied a general non-aqueous route for the formation of mono-, bi-, tri-, tetra, hexapod and multipod magnetic spinel ferrite metal oxide (CoFe 2 O 4 ) nanocrystals. The magnetic CoFe 2 O 4 nanocrystals were characterized by X-ray diffraction, high-resolution transmission electron microscopy, Ra...

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Bibliographic Details
Published in:New journal of chemistry 2019-07, Vol.43 (26), p.1259-1269
Main Authors: Hennous, Mohammed, Ramana, E. Venkata, Tobaldi, David M, Costa, Benilde F. O, Valente, M. A, Labrincha, Joao, Karmaoui, Mohamed
Format: Article
Language:English
Subjects:
Anisotropy
Cobalt ferrites
Coercivity
Dependence
Magnetic measurement
Magnetic properties
Magnetic transitions
Magnetism
Mossbauer spectroscopy
Nanocrystals
Nanoparticles
Parameter estimation
Raman spectroscopy
Spectrum analysis
Transmission electron microscopy
X-ray diffraction
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Summary:We applied a general non-aqueous route for the formation of mono-, bi-, tri-, tetra, hexapod and multipod magnetic spinel ferrite metal oxide (CoFe 2 O 4 ) nanocrystals. The magnetic CoFe 2 O 4 nanocrystals were characterized by X-ray diffraction, high-resolution transmission electron microscopy, Raman spectroscopy, magnetometry and Mössbauer spectroscopy, to understand their structure and magnetic properties. These CoFe 2 O 4 nanoparticles have the smallest particle size reported ever, with a mean diameter of ∼3 nm. The coercivity was found to be larger compared to that reported in the literature for spherical particles. Mössbauer spectroscopy indicated a magnetic transition above room temperature, where 20% of the Fe ions transit to a paramagnetic state, around 400 K. From the thermal dependence of magnetic parameters, the blocking temperature was estimated to be around 425 K. These studies indicate that our CoFe 2 O 4 nanocrystals are different from their cubic/spherical counterparts, which generally display a single domain character. These CoFe 2 O 4 nanocrystals display a strong shape anisotropy dependent magnetic property. A non-aqueous sol-gel route followed by oriented attachment to make multi-pod CoFe 2 O 4 nanocrystals showing large room temperature saturation magnetization.
ISSN:1144-0546
1369-9261
DOI:10.1039/c9nj02237f