In this work, four complexing agents participated in the synthesis of Ni 0.2 Zn 0.2 Co 0.6 Fe 2 O 4 ferrites by sol-gel route. The X-ray diffraction (XRD) pattern showed that samples had formed spinel phase. The Fourier transform infrared (FTIR) spectra of samples showed two absorption bands around 400 cm −1 and 600 cm −1 , which are the characteristics of spinel ferrites. SEM micrographs showed that the prepared particles had different shape. Vibrating sample magnetometer was used to characterize magnetic performances. The prepared samples showed typical hysteresis behaviors at room temperature. The Ni 0.2 Zn 0.2 Co 0.6 Fe 2 O 4 ferrite sample prepared with egg white as a complexing agent had high coercivity (1365.52 Oe) and remanent magnetization (23.95 emu/g), which indicated that the sample had a potential applications for magnetic storage devices. The sample prepared with egg white had a coercivity six times higher than coercivities (168.44-200.47 Oe) of other samples. These findings revealed that egg white is a suitable complexing agent to prepare Ni 0.2 Zn 0.2 Co 0.6 Fe 2 O 4 hard ferrite by sol-gel route. The optical properties are characterized using PL emission spectra and UV-visible absorption spectrum. From the optical band gap (Eg) value, the sample has the characteristics of a semiconductor material. KeywordsNi 0.2 Zn 0.2 Co 0.6 Fe 2 O 4 ferrite • Sol-gel route • Four complexing agents • Magnetic performances • Optical performances

In the present work, nanocrystalline Sb3+ ions doped Ni0.2Ba0.1Co0.7Fe2−xSbxO4 (0 ≦ x ≦ 0.1, step by 0.025) ferrites were prepared via sol-gel method. The spinel-phase structure of samples can be confirmed by X-ray diffraction (XRD) patterns. The composition and structure were further studied by fourier transform infrared spectroscopy (FTIR). There were two typical characteristic bands ν1 and ν2 related to the stretching vibrations in spinel ferrite in FTIR spectra. Energy dispersive spectrometer (EDS) analyzed the elements of samples. It indicated that the elements of Ni, Ba, Co, Fe, O and Sb existed in the samples. Vibrating sample magnetometer was used to characterize magnetic properties. The saturation magnetization decreased from 57.65 emu/g to 44.50 emu/g with the increasing Sb3+ ions content, which is attributed to Fe3+ ions replaced by the Sb3+ ions. Remanent magnetization and coercivity first decreased and then increased slightly.

Different complexing agents were used to prepare Ni-Mg-Zn ferrite with the composition formula Ni0.2Mg0.2Zn0.6Fe2O4 via sol-gel method, which included citric acid, oxalic acid, egg white and EDTA. The Ni0.2Mg0.2Zn0.6Fe2O4 ferrite with no complexing agent was also prepared as a comparison. The chemical phases of samples were analyzed by the X-ray diffraction (XRD), which indicated that samples had spinel phase structure. The lattice constants of samples are in the range of 8.3980~8.4089 Å. The composition and structure were further studied by fourier transform infrared spectroscopy (FTIR). There were two typical characteristic bands related to the stretching vibrations of spinel ferrite in FTIR spectra. Scanning electron microscope (SEM) micrographs and transmission electron microscope (TEM) images showed that the particles have the shape of spherical cube. Energy dispersive spectrometer (EDS) analyzed the elements and ingredients of samples, which included Ni, Mg, Zn, Fe and O. X-ray photoelectron spectroscopy (XPS) is used to examine further the elemental composition and chemical state of sample prepared with EDTA as complexing agent. The optical properties of samples were investigated by photoluminescence spectra and UV-Vis spectroscopy. Vibrating sample magnetometer (VSM) was used to characterize magnetic properties, hysteresis loops revealed the ferrimagnetism behavior of prepared samples.

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