Synthesis, characterization and magnetic properties of monodisperse Ni, Zn-ferrite nanocrystals

• Reverse microemulsion route is very facile route for synthesis of Ni1−xZnxFe2O4 ferrite.
• Presence of Zn changes the structural and magnetic properties of the Zn substituted NiFe2O4.
• The lattice constant increases with the increase in Zn substitution.
• The curie temperature decreases with Zn concentration appreciably.
• Magnetic behavior varies from ferromagnetic at x=0 to superparamagnetic to paramagnetic at x=1.

Synthesization of monodisperse Ni, Zn-ferrite (Ni1−xZnxFe2O4, x=1, 0.8, 0.6, 0.5, 0.4, 0.2, 0.0) nanocrystals has been achieved by the inverse microemulsion method using CTAB as surfactant and kerosene as an oil phase. The detailed characterization of the synthesized nanocrystals and measurement of the magnetic properties has been done by techniques like X-ray diffraction (XRD), field emission transmission electron microscopy (FETEM), Fourier transform infrared spectroscopy (FITR) and Vibrating Sample Magnetometer (VSM) respectively. The relationship between the structure and composition of the nanocrystals with magnetic properties has been investigated. The nanocrystals size is found to be in the range 1–5 nm. The effect of Zn substitution on size and magnetic properties has been studied. It has been observed that magnetism changed from ferromagnetic at X= 0 to super paramagnetic to paramagnetic at X=1 as Zn concentration increased. The Curie temperature is found to decrease with an increase in Zn concentration.