Anantharaman, M R; Narayanan, T N; Sakthi Kumar, D; Yasuhiko, Yoshida(Springer, July 30, 2008)
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Abstract:
Nano magnetic oxides are promising candidates for high density magnetic storage and other applications.
Nonspherical mesoscopic iron oxide particles are also candidate materials for studying the shape, size
and strain induced modifications of various physical properties viz. optical, magnetic and structural. Spherical
and nonspherical iron oxides having an aspect ratio, ~2, are synthesized by employing starch and ethylene glycol
and starch and water, respectively by a novel technique. Their optical, structural, thermal and magnetic
properties are evaluated. A red shift of 0⋅24 eV is observed in the case of nonspherical particles when compared
to spherical ones. The red shift is attributed to strain induced changes in internal pressure inside the
elongated iron oxide particles. Pressure induced effects are due to the increased overlap of wave functions.
Magnetic measurements reveal that particles are superparamagnetic. The marked increase in coercivity in the
case of elongated particles is a clear evidence for shape induced anisotropy. The decreased specific saturation
magnetization of the samples is explained on the basis of weight percentage of starch, a nonmagnetic component
and is verified by TGA and FTIR studies. This technique can be modified for tailoring the aspect ratio and
these particles are promising candidates for drug delivery and contrast enhancement agents in magnetic resonance
imaging
Description:
Bull. Mater. Sci., Vol. 31, No. 5, October 2008, pp. 759–766