محسن محرابی

A series of samarium doped cobalt ferrites with the nominal compositions of CoSmxFe2−xO4 (where x = 0, 0.02, 0.04, and 0.06 at.%) was synthesized using sol–gel auto-combustion method. The crystal structure, morphology and magnetic properties of the nanoparticles have been investigated. The XRD data analyzed by the MAUD program confirmed the successful substitution of Fe3+ by Sm3+cations in the unit cell of the cobalt ferrite lattice. The formation of nanosized spinel ferrites was confirmed by FESEM and FTIR analysis. The values of saturation magnetization (MS) decreased from 76 to 63 by increasing the Sm content from x = 0 to x = 0.06 at room temperature, whereas at 10 K, the decreasing tendency of MS was much weaker. The reduction of temperature from 300 to 10 K caused a remarkable growth of both the saturation magnetization and coercive field (HC). The coercivity of the sample with x = 0.06 at 10 K is strongly higher than the one at the room temperature. The influence of samarium ions and temperature-dependent magnetic response of CoFe2O4 nanoparticles was studied and their effect was discussed in terms of the geometrical proportions and magnetic anisotropy evolutions. The Sm doped cobalt ferrite is a suitable candidate for moderate permanent magnets and high density information storage, especially when in use at low temperatures.