Local structure and magnetic property of Ni1-xZnxFe2O4 (x=0, 0.25, 0.50, 0.75, 1.00) nanoparticles prepared by hydrothermal method

Ni1-xZnxFe2O4 nanoparticles were prepared by hydrothermal method at 220 degrees C for 8 h in aloe vera solution of pH 12. The phase structure, morphology and crystallite size were studied by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The results indicate that all samples have a cubic spinel ferrite structure and the estimated crystallite size by X-ray line broadening is in the range of 16-29 nm. Cations distribution of Ni1-xZnxFe2O4 were studied by X-ray absorption fine structure (XAFS), X-ray absorption near edge structure (XANES) at Ni, Zn and Fe K-edge and extended X-ray absorption fine structure (EXAFS) at Ni and Zn K-edge. Magnetic properties were investigated by using vibrating sample magnetometer (VSM). It is found that all samples behave ferrimagnetic with the saturation magnetization (M-s) of respectively 25.64 and 17.39 emu/g for NiFe2O4 and ZnFe2O4 and the M-s of Ni-Zn ferrite are increased with increasing of Zn content. The experimental and calculating results of EXAFS can be well fitted, indicating that most of Ni atoms occupy the octahedral site and some of them occupy the tetrahedral site while most of Zn atoms occupy the tetrahedral site and some of them occupy the octahedral site. In Ni-Zn ferrite, more octahedral sites can be occupied by Ni atoms as the Zn content is increased, resulting in the increasing of the saturation magnetization. (C) 2014 Elsevier B.V. All rights reserved.