Tuning magnetic and structural properties of MnFe2O4 nanostructures by systematic introduction of transition metal ions M2+ (M = Zn, Fe, Ni, Co)

Abstract

Manganese ion (Mn2+) in a ferrite nanostructure was partially substituted by different transition metal ions: Zn2+, Fe2+, Ni2+, and Co2+, in that respective order. The introduction of each different metal ion affected the size, the crystallographic parameters, and the magnetic properties of the ferrite nanoparticles. The magnetic properties changed accordingly with the individual characteristics of the selected transition metal ion, meaning that the introduction of a metal ion with lower coercivity like nickel or iron into the structure decreased the overall coercivity of the material; this also had an effect on increasing/decreasing the blocking temperature of the overall material. There were some unexpected variations at the crystalline structure and in its thermal stability, as demonstrated by X-ray diffraction, rietveld analysis, and TGA-DSC measurements. These changes can be attributed to lattice distortions caused by the substitution of different transition metal ions in the spinel structure, which affects its stability.