Magnetic Properties and Morphology of the Cobalt Particles Prepared in Different Liquid Solvent

Abstract:

The two kinds of flower-like ultrafine cobalt particles were prepared by reducing cobalt chloride (CoCl₂·6H₂O) with hydrazine hydrate (N₂H₄·H₂O) under ultrasonic and microwave radiation, in which ethanol-water or ethylene glycol-water mixture was used as solvent. The morphology, crystal structure and magnetic properties of the as-prepared particles were characterized by scanning electron microscope (SEM), x-ray diffraction pattern (XRD) and vibrating sample magnetometer (VSM). The results show that the petals of the flower-like cobalt particles prepared in the ethanol-water system were dendritic, while the petals of the flower-like cobalt particles prepared in the ethylene glycol-water system were sword-like. The crystal structure of cobalt particles prepared in the two kinds of systems both consisted of hexagonal close-packed cubic phase and face-centered cubic phase, but the relative content was different. The saturation magnetization of the cobalt particles with dendritic petals and the cobalt particles with sword-like petals was the same approximately, but their coercivity was greatly different (the difference in value about 7184.14Am^-1), which might be attributed to the magnetocrystalline anisotropy and shape anisotropy.

• Periodical: Materials Science Forum (Volume 749)
• Pages: 192-197
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.749.192
• Online since: March 2013
• Authors: Xue Min Huang, Quan Sheng Wang, Ying Liu, Xiu Chen Zhao, Shu Lai Wen
• Keywords: Cobalt Particles, Coercivity, Hydrazine Reduction

References

[1] H.Y. Chen, et al., Preparation of magnetic cobalt nanoparticles by reducing hydrazine, Modern Chemical Industry. 25 (2005) 219-223.

[2] P. Vargas, et al., Magnetism of nanosized metallic Co-clusters, Journal of Magnetism and Magnetic Materials. 226 (2001) 603-605.

DOI: 10.1016/s0304-8853(00)00691-0

[3] H.D. Jang, D.W. Hwang, et al., Preparation of cobalt nanoparticles by hydrogen reduction of cobalt chloride in the gas phase, Materials Research Bulletin. 39 (2004) 63-70.

DOI: 10.1016/j.materresbull.2003.09.023

[4] Y.P. Bao, M. Beerman, et al., Controlled crystalline structure and surface stability of cobalt nanocrystals, J. Phys. Chem. B. 109 (2005) 7220-7222.

DOI: 10.1021/jp044363n

[5] X.H. Zhang, K.M. Wu, A.H. Wong, et al., Hydrothermal microemulsion synthesis of oxidatively stable cobalt nanocrystal encapsulated in surfactant/polymer complex shells, Langmuir. 26 (2010) 6009-6014.

DOI: 10.1021/la9045918

[6] B. Liu, J.G. Guan, et al., Preparation of nanometer cobalt particles by polyol reduction process and their magnetic characterizations, Journal of functional materials. 36 (2005) 1122-1125.

[7] F. Liang, J.X. He, X.Z. Cao, et al., Synthesis and characterization of cobalt nanoparticles, Rare Metal Materials and Engineering. 36 (2007) 760-762.

[8] S.Z. Wang, J. Sun, et al., A study of laser surface phase transition hardening quenching for high cobalt cemented carbide, The Chinese Journal of Nonferrous Metals. 8 (1998) 89-93.

[9] S. Sun, C. B. Murray, Synthesis of monodisperse cobalt nanocrystals and their assembly into magnetic superlattices (invited), J. Appl. Phys. 85 (1999) 4325-4330.

DOI: 10.1063/1.370357

[10] J.G. Li, Y. Qin, X.L. Kou, et al., Structure and magnetic properties of cobalt nanoplatelets, Materials Letters. 58 (2004) 2506-2509.

DOI: 10.1016/j.matlet.2004.03.026

[11] D.P. Dinega, M.G. Bawendi, A solution-phase chemical approach to a new crystal structure of cobalt, Angewandte Chemie International Edition. 38 (1999) 1788-1791.

DOI: 10.1002/(sici)1521-3773(19990614)38:12<1788::aid-anie1788>3.0.co;2-2