The contact of a steel electrode with water dispersion medium in an open-air system leads to the development of various polymorphic iron oxides and oxyhydroxides on the steel surface. Whereas the usage of distilled water causes the obtaining of Fe(II)-Fe(III) layered double hydroxides (green rust) as a primary mineral phase, but in the presence of inorganic 3d-metal water salt solutions, mixed ...

The efficient surface reaction and rapid ion diffusion of nanocrystalline metal oxides have prompted considerable research interest for the development of high functional materials. Herein, we present a novel low-temperature method to synthesize ultrasmall nanocrystalline spinel oxides by controlling the hydration of coexisting metal cations in an organic solvent. This method selectively led to...

Industrial Cu-smelters still suffer from metal rich droplet losses in slags due to insufficient phase separation. One important factor in the mechanical entrainment of metal rich droplets in slags is their attachment to solid spinel particles, which are also present in the slag phase. Consequently, these particles hinder the settling of the metal droplets. In order to improve phase separation i...

Electron beam irradiation is well known to induce damage in materials. The structural transformation involved in the damage is usually believed to be an irreversible solid state chemical reaction. Here we use in situ transmission electron microscopy (TEM) combined electron-energy loss spectroscopy (EELS) technique in an aberration-corrected TEM to track the structural transformation in spinel M...

Rechargeable metal-air batteries are considered a promising energy storage solution owing to their high theoretical energy density. The major obstacles to realising this technology include the slow kinetics of oxygen reduction and evolution on the cathode (air electrode) upon battery discharging and charging, respectively. Here, we report non-precious metal oxide catalysts based on spinel-type ...

Ferrites with spinel structure are the most widespread materials in radio engineering, electronics and communication industry, microwave devices and computer facilities. The change of synthesis temperature of ferrites results in cation redistribution of iron, which updates crystal properties, as macroscopic magnetic properties of ferrites. Among this extensive class of compounds nickel and copp...

The surface and bulk compositions of the mixed metal oxide CoxNi1−xO have been compared over the entire range of stoichiometry 0 ≤ x ≤ 1. The materials, which were formed as polycrystalline solid solutions, were shown to be well-ordered and homogeneous in the bulk, but tend to deviate in their surface composition for x 0.6. Auger and X-ray photoelectron spectroscopy gave comparable results and ...

Homogeneous lithium-rich layered-spinel 0.5Li2MnO3·0.5LiMn1/3Ni1/3Co1/3O2 microspheres (~1 μm) are successfully prepared by a solvothermal method and subsequent high-temperature calcinations process. The effects of temperature on the structure and performance of the as-prepared cathode material are systemically studied by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission...

Density functional theory (DFT) calculations have been performed on A(2+)B2(3+)O4(2-) (where A(2+) = Fe, Ni or Zn, and B(3+) = Fe or Cr) spinel oxides in order to determine some of their thermodynamic properties. Mixing energies were calculated for Fe3O4-NiFe2O4, Fe3O4-ZnFe2O4, Fe3O4-FeCr2O4, NiFe2O4-ZnFe2O4, NiFe2O4-NiCr2O4, FeCr2O4-NiCr2O4, FeCr2O4-ZnCr2O4 and ZnCr2O4-ZnFe2O4 pseudo-binaries ...

An equimolar mixtures of starting ZnO and Cr2O3 powders were mechanically activated by grinding using a planetary ball mill for various periods of time (40 to 320 minutes). Formation of nanocrystalline ZnCr2O4 as normal spinel structure at room temperature is detected in all samples after ball-milling. A detailed XRD structural analysis (lattice parameters, site occupancy, the average primary c...