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

authors	Hennous, M; Ramana, EV; Tobaldi, DM; Costa, BFO; Valente, MA; Labrincha, J; Karmaoui, M
nationality	International
journal	NEW JOURNAL OF CHEMISTRY
keywords	COFE2O4 NANOPARTICLES; EFFICIENT CATALYST; HIGH COERCIVITY; PERFORMANCE; SIZE; PARTICLES; OXIDE; CO; PLATFORM; ARRAYS
abstract	We applied a general non-aqueous route for the formation of mono-, bi-, tri-, tetra, hexapod and multipod magnetic spinel ferrite metal oxide (CoFe2O4) nanocrystals. The magnetic CoFe2O4 nanocrystals were characterized by X-ray diffraction, high-resolution transmission electron microscopy, Raman spectroscopy, magnetometry and Mossbauer spectroscopy, to understand their structure and magnetic properties. These CoFe2O4 nanoparticles have the smallest particle size reported ever, with a mean diameter of similar to 3 nm. The coercivity was found to be larger compared to that reported in the literature for spherical particles. Mossbauer 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 CoFe2O4 nanocrystals are different from their cubic/spherical counterparts, which generally display a single domain character. These CoFe2O4 nanocrystals display a strong shape anisotropy dependent magnetic property.
publisher	ROYAL SOC CHEMISTRY
issn	1144-0546
isbn	1369-9261
year published	2019
volume	43
issue	26
beginning page	10259
ending page	10269
digital object identifier (doi)	10.1039/c9nj02237f
web of science category	Chemistry, Multidisciplinary
subject category	Chemistry
unique article identifier	WOS:000474625700004