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Title: Synthesis, characterization and magnetic properties of ultrafine Co{sub 3}O{sub 4} octahedra

Octahedral Co{sub 3}O{sub 4} nanoparticles were synthesised in an aqueous ammonia solution using hexagonal β-Co(OH){sub 2} nanoplates as starting materials. Electron microscopy analysis indicates that the Co{sub 3}O{sub 4} 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 Co{sub 3}O{sub 4} nanoparticles coincides with crystallographic <111> 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 Co{sup 2+}. The results show that a substantial fraction of the B-site Co{sup 3+} in the nanoparticles is in a high-spin state.
Authors:
; ; ; ; ; ;  [1] ;  [2]
  1. School of Physics and Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), Trinity College, Dublin 2 (Ireland)
  2. School of Chemistry, Trinity College, Dublin 2 (Ireland)
Publication Date:
OSTI Identifier:
22492302
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Advances; Journal Volume: 5; Journal Issue: 8; Other Information: (c) 2015 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; AMMONIA; ANTIFERROMAGNETISM; COBALT HYDROXIDES; COBALT IONS; COBALT OXIDES; CUBIC LATTICES; CURIE POINT; ELECTRON MICROSCOPY; HIGH SPIN STATES; MAGNETIC PROPERTIES; MAGNETIC SUSCEPTIBILITY; MAGNETIZATION; NANOPARTICLES; PARAMAGNETISM; RESOLUTION; SPINELS; SYNTHESIS; TEMPERATURE DEPENDENCE