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Particle Size Control, Structure and Magnetic Characterization of Cobalt Nanoparticles

Published online by Cambridge University Press:  21 March 2011

Abhishek Singh ,
Nirav Parekh ,
Gregory Young ,
Kiumars Parvin ,
Maninder Kaur ,
David Bruck ,
Spencer Wong  and
Mehdi Varasteh
Abhishek Singh
Affiliation:
Chemical and Materials Engineering, San Jose State University, One Washington Square, San Jose, CA, 95192
Nirav Parekh
Affiliation:
Chemical and Materials Engineering, San Jose State University, One Washington Square, San Jose, CA, 95192
Gregory Young
Affiliation:
Chemical and Materials Engineering, San Jose State University, One Washington Square, San Jose, CA, 95192
Kiumars Parvin
Affiliation:
Physics, San Jose State University, One Washignton Square, San Jose, CA, 95192
Maninder Kaur
Affiliation:
Physics, San Jose State University, One Washignton Square, San Jose, CA, 95192
David Bruck
Affiliation:
Biology, San Jose State University, One Washington Square, San Jose, CA, 95192
Spencer Wong
Affiliation:
Biology, San Jose State University, One Washington Square, San Jose, CA, 95192
Mehdi Varasteh
Affiliation:
Alza Corporation, Mountain View, CA, 94039
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Abstract

Cobalt nanoparticles were synthesized by means of a hot metal reduction reaction with cobalt chloride as precursor material. The size of cobalt nanoparticles was controlled by the choice of surfactant and the molar ratio of surfactant-to-reagent. Surfactants with larger alkane side chains yielded a smaller average nanoparticle size (diameter) and tighter size distribution, as these chains provided steric hindrance to the growth of the nanoparticles after initial nucleation. For each alkane side chain, a high molar ratio of surfactant-to-reagent (HSR) rendered nanoparticles with smaller particle size, while a low molar ratio of surfactant-to-reagent (LSR) produced larger nanoparticles. Measurements on transmission electron microscope images of cobalt particles synthesized with tri-octylphosphine revealed an average particle size of 6.9 nm (HSR) and 9.1 nm (LSR), while particles synthesized with tri-butylphosphine had a mean diameter of 12.5 nm (HSR) and 14.9 nm (LSR). X-ray diffraction profiles indicated that particles had metastable ε-cobalt structure. Room temperature magnetization measurements showed ferromagnetic behavior with highly square M-H loops indicative of single domain particles with coercive fields in the range of 400–500 Oe.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 998: Symposium J – Nanoscale Magnetics and Device Applications , 2007 , 998-J01-04
Copyright
Copyright © Materials Research Society 2007

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References

REFERENCES

1. Sun, S., Murray, C.B., Doyle, H., “Controlled assembly of monodisperse ε-cobalt-based nanocrystals,” Mat. Res. Soc. Symp. Proc. 577:385 (1999).Google Scholar
2. Murray, C.B., Sun, S., Gaschler, W., Doyle, H., Betley, T.A., Kagan, C.R., “Colloidal synthesis of nanocrystals and nanocrystal superlattices,” IBM J.Res. Devel. 45 (1):47–56 (2001).Google Scholar
3. Su, Y.K., Shen, C.M., Yang, T.Z., Yang, H.T., Li, H.L. and Gao, H.J., “Synthesis and characterization of monodisperse cobalt nanocrystals and nanocrystalline superlattices,” Adv. Nanomaterials Nanodevices IUMRS-ICEM:486–500 (2002).Google Scholar
4. Puntes, V.F., Krishnan, K.M., Alivisatos, A.P.. Colloidal nanocrystal shape and size control: the case of cobalt. Sci. 291:2115–2117 (2001).Google Scholar
5. Sun, S., Murray, C.B., “Synthesis of monodisperse cobalt nanocrystals and their assembly into magnetic superlattices,” J. of App. Phys. 85(8):4325–4330 (1999).Google Scholar
6. University of Texas Health Science Center at San Antonio, UTHSCSA Image Tool 3.0, http://ddsdx.uthscsa.edu/dig/itdesc.htmlGoogle Scholar