Effect of mechanochemical synthesis on the structure, magnetic and optical behavior of Ni1-xZnxFe2O4 spinel ferrites

Ni1-xZnxFe2O4 (0 <= x <= 1) nanocrystals were prepared by a soft mechanochemical approach. The structure and morphology were assessed via X-ray powder diffractometery (XRD), infrared spectroscopy (FTIR), Raman spectroscopy, transmission electron microscopy (TEM) and Energy dispersive spectroscopy (EDS). The magnetic characteristics have been evaluated using vibrating sample magnetometer (VSM). The optical properties were explored by diffuse reflectance UV-visible spectrophotometry (DRS). The substitution of Zn into the Ni1-xZnxFe2O4 nanocrystals increased the mean nanocrystal size from 4 to 19 nm. The FTIR and Raman spectroscopies showed that the substitution with Zn up to x=0.5 in Ni1-xZnxFe2O4 nanocrystals results in a migration of Fe ions from tetrahedral to octahedral sites, leading to an improvement of the saturation magnetization value to 33.8 emu/g. At the same time, the optical band gap decreased from 2.6 to 1.93 eV due to the increase of the Zn content from x=0 to x=1. These promising characteristics of Ni1-xZnxFe2O4 nanocrystals make them suitable for the use in the field of magnetically recoverable catalysts including those for energy applications.