Structural features of the iron-oxygen nanoparticles formed when the rotation-corrosion dispergation method is applied

1. According to X-ray diffraction (XRD) data the iron-oxygen particles obtained when the rotation-corrosion dispergation method was applied contain the products of the phase transformation of the main phase and structural elements of its phase-precursors in their structure. Ferrihydrite and Fe(II)-Fe(III) layered double hydroxides (Green Rust) relate to the phase-precursors in the systems based on the iron (steel). So, some structural elements of iron oxyhydroxides as well as hematite are included into ferrihydrite structure. Whereas Green Rusts contain the corresponding anions, water and iron oxide admixtures in its structure alongside with the lepidocrocite and goethite phases. 2. The process of the phase transformation of the phase-precursors strongly depends on red-ox conditions. While under oxidative conditions the iron oxyhydroxides are formed in the system, under reductive condition in the presence of the ferrous species the magnetite particles are the typical product of the phase transformation. But in the absence of ferrous species in the water medium the lepidocrocite ⌷-FeOOH transformation leads to the maghemite ⌷-Fe₂O₃ formation. Lepidocrocite has a plate-like morphology, it is heterogeneous and contains goethite phase as admixture. The following structural elements were found in the magnetite structure: sulphate and carbonate anions, goethite, hematite, maghemite and lepidocrocite admixtures. 3. Spinel ferrites obtained when the RCD (rotation-corrosion dispergation)-method was applied correspond to the non-stoichiometric structures where zinc, nickel or cobalt atoms replace ferrous atoms. The Fourier transform infrared spectroscopy (FTIR) spectra of such particles have a few differences from stoichiometric spinel ferrites due to the presence of the anions as well as structural elements of Green Rust and iron oxyhydroxides. 4. The structure of the core&shell composite FeFe₂O₄&Ag^º includes the following features: 1) the core degradation under condition when the colloidal particles are instable; 2) the presence of argentum atoms in the magnetite structure as well as silver on its surface; 3) the silver shell porosity or its island-like structure etc. (author)