Effect of Ni2+ substitution on structural and magnetic properties of Ni–Zn ferrite nanoparticles

• The co-precipitation method support to prepare ultrafine ferrite nanoparticles.
• The excellent magnetic properties obtained at low annealing temperatures.
• Ni2+ substitution affect magnetic anisotropy in Ni–Zn ferrite nanoparticles.

A series of co-precipitated NixZn1−xFe2O4 (x=0.5, 0.6, 0.7) ferrite nanoparticles heat treated at 200 °C were produced in order to understand the influence of substitution level on structural and magnetic properties including magnetocrystalline anisotropy. The XRD, FE-SEM, VSM and FC–ZFC techniques were used to characterize the samples. It is observed that as Ni2+ concentration increases crystallite size (D), saturation magnetization (Ms) and blocking temperature (TB) and decreases coercive field (Hc). All particles exhibit superparamagnetism at room temperature and hence lie in the single domain range. The magnetic anisotropy constant (K) is estimated to be maximum for Ni0.5Zn0.5Fe2O4 sample, whose particle size is the smallest. The results are interpreted presuming the presence of core shell interactions and/or cation redistribution that influence the magnetic properties of these ferrite nano particles.