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...

Magnetic properties of single crystals of cobalt and substituted cadmium-cobalt spinel ferrites are presented under high magnetic field up to 180 kOe in the 4.2-300 K temperature range for five substitution rates. The easy direction of magnetization is [loo] whereas abrupt field transitions are observed below 150 K for the [Ill] direction. The influence of the cadmium substitution on the molecu...

Core@shell and concentration-gradient particles have attracted much attention as improved cathodes for Li-ion batteries (LIBs). However, most of their preparation routes have employed a precisely-controlled co-precipitation method. Here, we report a facile preparation route of core@shell and concentration-gradient spinel particles by dry powder processing. The core@shell particles composed of t...

Metal oxides of the spinel family have shown great potential towards the oxygen evolution reaction (OER), but the fundamental OER mechanism of spinel oxides is still far from being completely understood, especially for the role of the metal ions. Owing to various coordinated sites of divalent/trivalent metals ions and surface conditions (morphology and defects), it is a great challenge to have ...