Calcium-assisted reduction of cobalt ferrite nanoparticles for nanostructured iron cobalt with enhanced magnetic performance

  • B. Qi
  • J. S. Andrew
  • D. P. ArnoldEmail author
Research Paper


This paper demonstrates the potential of a calcium-assisted reduction process for synthesizing fine-grain (~100 nm) metal alloys from metal oxide nanoparticles. To demonstrate the process, an iron cobalt alloy (Fe66Co34) is obtained by hydrogen annealing 7-nm cobalt ferrite (CoFe2O4) nanoparticles in the presence of calcium granules. The calcium serves as a strong reducing agent, promoting the phase transition from cobalt ferrite to a metallic iron cobalt alloy, while maintaining high crystallinity. Magnetic measurements demonstrate the annealing temperature is the dominant factor of tuning the grain size and magnetic properties. Annealing at 700 °C for 1 h maximizes the magnetic saturation, up to 2.4 T (235 emu/g), which matches that of bulk iron cobalt.


Magnetic nanomaterials Iron cobalt Calcium-assisted reduction High saturation Grain evolution 



This work was supported in part by the US Army Research Office (W911NF-09-1-0511) and National Science Foundation (CMMI-1451993). The authors thank Stefan Kelly for assistance in the DLS measurements, Lorena Maldonado-Camargo and Dr. Carlos Rinaldi for making the FC/ZFC measurements, and the UF MAIC facility for the invaluable support in material characterization.

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.

Supplementary material

11051_2017_3797_MOESM1_ESM.docx (14 kb)
ESM 1 (DOCX 13 kb)


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Copyright information

© Springer Science+Business Media Dordrecht 2017

Authors and Affiliations

  1. 1.Interdisciplinary Microsystems Group, Department of Electrical and Computer EngineeringUniversity of FloridaGainesvilleUSA
  2. 2.Department of Materials Science and EngineeringUniversity of FloridaGainesvilleUSA

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