MAGMA56371

Journal of Magnetism and Magnetic Materials, 2010

Magnetic and structural properties of single-phase Gd 3+ -substituted Co-Mg ferrite nanoparticles, 2020

Nanocrystalline Gd 3+-doped Co-Mg ferrite nanoparticles with the chemical formula Co 0.7 Mg 0.3 Fe (2Àx) Gd x O 4 (x ¼ 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 Fd 3m 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 À1 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 À1 , larger than that of pure bulk cobalt ferrite (80.8 emu g À1). Only ferrite cobalt synthesized sonochemically has been reported to have a higher saturation magnetization (92.5 emu g À1).

Molecules, 2020

Applied Sciences

The magnetic properties of pure and rare earth ion-doped Fe3O4 nanoparticles are investigated using a microscopic model and the Green’s function theory. The magnetization Ms and Curie temperature TC are calculated depending on size, temperature and Gd doping concentration. Ms and TC decrease with decreasing nanoparticle size and with increasing the doping concentration. The band gap energy increases with decreasing size and Gd dopants. The obtained results are in good agreement with the experimental data.

RSC Advances

Rare earth (RE) ions are known to improve the magnetic interactions in spinel ferrites if they are accommodated in the lattice, whereas the formation of a secondary phase leads to the degradation of the magnetic properties of materials.

Materials Science and Engineering: C, 2007