A study of ZnFe2O4 nanoparticles modified by ferric nitrate

Transmission electron microscopy (TEM), energy-dispersive X-ray spectrometry (EDX), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) revealed that ZnFe2O4 particles treated with an Fe(NO3)3 solution had a three-shell structure, comprising a ZnFe2O4 core, an external γ-Fe2O3 shell, and an outer, mixed Fe(NO3)3·9H2O and ZnO layer. The concentration of the Fe(NO3)3 solution played an important role in the treatment; it determined the ratio of the chemical species and the size of the particles. The magnetization of the treated particle was related to the concentration in a non-monotonic fashion, because of the competition between the ferrimagnetic γ-Fe2O3 phase and the nonmagnetic Fe(NO3)3·9H2O/ZnO mixture. The experiments showed that only below a concentration of 0.5 M was the magnetization of the treated particle enhanced with increasing concentration of the Fe(NO3)3 solution. - Highlights: ► The structure of surface modified ZnFe2O4 nanoparticles by Fe(NO3)3 is studied using TEM, EDX, XPS, XRD and VSM. ► This modified particles have a ZnFe2O4 core, an external γ-Fe2O3 shell and an other mixed Fe(NO3)3·9H2O and ZnO layer. ► The magnetization of the modified particles is related to the concentration of Fe(NO3)3solution in a non-monotonic fashion. ► Below a concentration 0.5 M, the magnetization of the modified particle enhanced with increasing the concentration.