Synthesis, characterization and magnetic properties of ultrafine Co3O4 octahedra

Octahedral Co3O4 nanoparticles were synthesised in an aqueous ammonia solution using hexagonal β-Co(OH)2 nanoplates as starting materials. Electron microscopy analysis indicates that the Co3O4 particles have diameters of 20-40 nm and adopt a well-crystallized cubic spinel structure. The octahedral h...

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Bibliographic Details
Published in:AIP advances 2015-08, Vol.5 (8), p.087122-087122-7
Main Authors: Chen, Y. H., Zhou, J. F., Mullarkey, D., O’Connell, R., Schmitt, W., Venkatesan, M., Coey, M., Zhang, H. Z.
Format: Article
Language:English
Subjects:
Ammonia
Antiferromagnetism
Cobalt oxides
Crystallization
Crystallography
Curie temperature
High resolution electron microscopy
Image resolution
Magnetic permeability
Magnetic properties
Magnetism
Microscopy
Nanoparticles
Ultrafines
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Summary:Octahedral Co3O4 nanoparticles were synthesised in an aqueous ammonia solution using hexagonal β-Co(OH)2 nanoplates as starting materials. Electron microscopy analysis indicates that the Co3O4 particles have diameters of 20-40 nm and adopt a well-crystallized cubic spinel structure. The octahedral habit was verified by high angle annular dark field imaging. High resolution electron microscopy results revealed that the long axis of the octahedral Co3O4 nanoparticles coincides with crystallographic direction and the facets are the {111} planes. Magnetization measurements reveal antiferromagnetic ordering below 10 K, with a paramagnetic Curie temperature of 3 K and a paramagnetic susceptibility that is double that expected for high-spin Co2+. The results show that a substantial fraction of the B-site Co3+ in the nanoparticles is in a high-spin state.
ISSN:2158-3226
2158-3226
DOI:10.1063/1.4928494