Magnetic and structural properties of single-phase Gd-substituted Co-Mg ferrite nanoparticles.

Nanocrystalline Gd-doped Co-Mg ferrite nanoparticles with the chemical formula CoMgFeGd O ( = 0.02) were prepared by coprecipitation for the first time. The properties of the nanoparticles were investigated by X-ray diffraction, confirming a single-phase, highly crystalline cubic spinel structure in the space group 3̄ and an average crystallite size of 54 nm. The Fourier-transform infrared spectrum showed two fundamental absorption bands in the wavenumber range of 437-748 cm attributed to the stretching vibration of tetrahedral and octahedral sites in the spinel structure. Scanning electron microscopy analysis showed that the nanoparticles are different in shape and slightly agglomerated. Energy-dispersive X-ray spectroscopy demonstrated the purity of the nano-ferrite powder. Magnetic measurements revealed ferrimagnetic behavior at room and low temperatures with high coercivity and a high saturation magnetization of 95.68 emu g, larger than that of pure bulk cobalt ferrite (80.8 emu g). Only ferrite cobalt synthesized sonochemically has been reported to have a higher saturation magnetization (92.5 emu g).