Synthesis and characterization of nonstoichiometric potassium/magnesium nanoferrites for multifunctional applications

In the present study, morphology, size distribution, and magnetic properties of magnesium/potassium nano ferrite samples with the chemical formula Mg0.5+x K1-2xFe2O4; 0 <= x <= 0.35 have been reported. The X-ray diffraction analysis of the studied samples confirms the formation of single phase cubic spinel structure. This phase is prepared with Mg-K/Fe ratio ranging from 0.5 to 1.5. The average crystallite sizes are in the range 24-31 nm. The obtained data shows that nonstoichiometry (Oxygen deficient or excess metal) affects strongly the Curie temperature. The flexibility in the structure of the nanoparticles enables large deviations from the stoichiometric MeFe2O4 composition without losing the single-phase spinel structure. However, potassium ions, K1+ (non magnetic ion) enhance the values of Tc for the studied samples. This enhancement provides the basis for a broad range of applications. On the other side the possibility of incorporating Mg/K at the tetrahedral and octahedral sites in the non-stoichiometric composition provides an opportunity to incorporate more metals (Mg/K) in the spinel structure compared to that of the stoichiometric MFe2O4 composition.