Structure and magnetic properties evolution of rod-like Co_(0.5)Ni_(0.25)Zn_(0.25)Dy_xFe_(2-x)O_4 synthesized by solvothermal method

摘要

A series of Dy~(3+) doped Co-Ni-Zn ferrites with the formula Co_(0.5)Ni_(0.25)Zn_(0.25)Dy_xFe_(2-x)O_4 0 ≤ x ≤ 0.24) have been successfully synthesized using the solvothermal method. X-ray diffraction and scanning electron microscope examinations indicate that a highly-crystallized cubic Co_(0.5)Ni_(0.25)Zn_(0.25)Dy_xFe_(2-x)O_4 with rod-like morphology is obtained when the precursor is calcined at 1000 ℃ in air for 3 h. Single phase Co_(0.5)Ni_(0.25)Zn_(0.25)Fe_2O_4 is obtained at 650 ℃, but all samples consist of the main spinel phase in combination of a small amount of a foreign Dy_2O_3 phase after doping Dy. When the precursor is calcined at 1000 ℃, the lattice parameter of the ferrites initially increase after doping Dy, but then become smaller with increasing Dy content. The addition of Dy content results in a reduction of crystallite size, attributed that the binding energy of Dy~(3+)-O~(2-) is larger than that of Fe~(3+)-O~(2-). Dy~(3+) substitution can decrease the remanence (Mr) and coercivity (Hc) of Co_(0.5)Ni_(0.25)Zn_(0.25)Dy_xFe_(2-x)O_4 samples, which are very desirable characteristics for high density data storage devices.