Effects of Ce3+ doping on the structural, magnetic and hyperfine properties of cobalt ferrite nanoparticles

We report on the structural, magnetic, and hyperfine properties of cobalt ferrite nanoparticles substituted with a minor fraction of Ce3+. Sol-gel technique was utilized to prepare CoCexFe2-xO4 (x=0.0,0.05and0.10) nanoparticles. Rietveld refinement of x-ray diffraction patterns show that all the samples crystallize in a face-centered cubic symmetry. The cell parameter increases while the grain size decreases with increasing Ce3+ concentration. Magnetic measurements show a reduction of saturation magnetization, remanent magnetization and total magnetic moment with increasing Ce3+ content. Furthermore, M(T) curves indicate that CoCe(x)Fe(2-x)O(4 )powders show various magnetic phases before paramagnetic state: region (i) canted antiferromagnetic or weak-ferromagnetic state with its respective Morin temperature (T-M), (ii) canted antiferromagnetic with the corresponding N & eacute;el temperature (T-N). M & ouml;ssbauer measurements were performed as well and the hyperfine field H-hf was related to Ce content. The magnitudes of isomer shift (IS) of all samples show that iron are present in trivalent state (Fe3+).