Structure and magnetic properties of hydrothermally synthesized CuFe2O4 and CuFe2O4/rGO composites

Abstract

This paper presents a comparative analysis of the structural and magnetic modifications in ultrafine CuFe2O4 and CuFe2O4/rGO nanocomposites subjected to annealing. Samples were investigated using X-ray diffraction and Mössbauer spectroscopy. The study outlines the impacts of the annealing temperature on key characteristics, including the lattice parameter, inversion degree, and crystallite sizes. Copper ferrite nanoparticles demonstrate temperature stability as a composite element, displaying the simultaneous presence of both cubic and tetragonal ferrite phases at 500 and 600 °C. For heterogeneous copper ferrite, alterations in magnetocrystalline anisotropy values were calculated as a function of the inversion degree. The investigation also explores the influence of both crystallite size and inversion degree on the characteristic time of magnetic moment relaxation in a single domain CuFe2O4 nanoparticle, setting a precondition for the observation of superparamagnetic CuFe2O4 nanoparticles via the Mössbauer method. The study introduces a model for the inception of a copper ferrite phase predicated on the partial charge theory, offering an analysis of protolysis and polycondensation processes during the interaction of iron and copper hydroxocomplexes. The role of negatively charged graphene oxide nanosheets as ferrite phase nuclei localization centers is further substantiated within this context.