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Experimental study of the structural and magnetic properties of gamma-Fe2O3 nanoparticles.
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Structural and magnetic properties of -Fe2O3 nanoparticles annealed at 200 and 250 °C have been studied
by using high resolution transmission electron microscopy TEM, electron energy loss spectroscopy, x-ray
diffraction, neutron diffraction, polarized small angle neutron scattering SANS and dc magnetization techniques.
Here we have dealt with an important problem of the symmetry of crystal structure of -Fe2O3
nanoparticles with cation vacancy distribution. Present study also correlates various structural and magnetic
results that have been obtained for -Fe2O3 nanoparticles using various experimental techniques. Analysis of
x-ray and neutron diffraction data shows cation vacancies at the octahedral site, consistent with the space group
P43 3 2. A log-normal distribution of particle size for both the samples has been found. A good crystallinity has
been found from TEM, x-ray diffraction and neutron diffraction studies. Neutron diffraction study at room
temperature confirms a ferrimagnetic ordering of tetrahedral and octahedral site moments with a net moment of
1.58 and 1.83 B per formula unit for the samples annealed at 200 and 250 °C, respectively. SANS data
analysis is consistent with a mass fractal spatial arrangement of these nanoparticles with a fractal dimension of
1.25. The SANS results are consistent with the same form factor for both the chemical particle size and the
magnetic particle size indicating the absence of any observable shell with disordered spins. Superparamagnetic
behavior of noninteracting nanoparticles with a log-normal distribution of blocking temperature with a particle
moment of 28 000 B for the sample annealed at 200 °C is found in our dc magnetization study at room
temperature.
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YUSUF, S. m., TERESA, J. m. de, MUKADAM, M. d., KOHLBRECHER, J., IBARRA, M. r., ARBIOL I COBOS, Jordi, SHARMA, P., KULSHRESHTHA, S. k.. Experimental study of the structural and magnetic properties of gamma-Fe2O3 nanoparticles.. _Physical Review B_. 2006. Vol. 74, núm. 22, pàgs. 224428/1-224428/11. [consulta: 23 de gener de 2026]. ISSN: 0163-1829. [Disponible a: https://hdl.handle.net/2445/10629]