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http://dx.doi.org/10.4283/JKMS.2008.18.2.063

Magnetization and Magnetic Entropy Change in Superparamagnetic Co-Ferrite Nanoparticle  

Ahn, Yang-Kyu (Department of Chemistry, Konyang University)
Choi, Eun-Jung (Department of Ophthalmic Optics, Konyang University)
Abstract
In order to the magnetization and magnetic entropy change for superparamagnetic ferrite nanoparticles, ultrafine cobalt ferrite particles were synthesized using a mircoemulsion method. The peak of X-ray diffraction pattern corresponds to a cubic spinel structure with the lattice constant 8.40 $\AA$. The average particle size, determined from X-ray diffraction line-broadening using Scherrer's, is 7.9 nm. The maximal magnetizations measured at 5 and 300 K are 24.3 emu/g and 17.2 emu/g, respectively. Superparamagnetic behavior of the sample is confirmed by the coincidence of the M vs. H/T plots at various temperatures. According to the thermodynamic theory, magnetic entropy change decreases with increasing temperature.
Keywords
ferrite; superparamagnetism; magnetization; magnetic entropy change;
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