Joegoldsteinite, a new sulfide mineral of end-member formula MnCr2S4, was discovered in the Social Circle IVA iron meteorite. It is a thiospinel, the Mn analog of daubréelite (FeCr2S4), and a new member of the linnaeite group. Tiny grains of joegoldsteinite were also identified in the Indarch EH4 enstatite chondrite. The chemical composition of the Social Circle sample determined by electron mi...

The spinel cobalt oxide Co3O4 is a magnetic semiconductor containing cobalt ions in Co2+ and Co3+ oxidation states. We have studied the electronic, magnetic, and bonding properties of Co3O4 using density functional theory (DFT) at the Generalized Gradient Approximation (GGA), GGA+U, and PBE0 hybrid functional levels. The GGA correctly predicts Co3O4 to be a semiconductor but severely underestim...

An effective integrated design with a free standing and carbon-free architecture of spinel MnCo2O4 oxide prepared using facile and cost effective hydrothermal method as the oxygen electrode for the Li-O2 battery, is introduced to avoid the parasitic reactions of carbon and binder with discharge products and reaction intermediates, respectively. The highly porous structure of the electrode allow...

The reaction mechanism of glycerol hydrogenolysis to 1,2-propanediol over a spinel CuCr2 O4 catalyst was investigated by using DFT calculations. Theoretical models were developed from the results of experimental characterization. Adsorption configurations and energetics of the reactant, intermediates, final product, and transition states were calculated on Cu(1 1 1) and CuCr2 O4 (1 0 0). Based ...

The demand for efficient and environmentally-benign electrocatalysts that help availably harness the renewable energy resources is growing rapidly. In recent years, increasing insights into design of water electrolysers, fuel cells, metal–air batteries emerge in response to need developing sustainable carriers, which oxygen evolution reaction reduction play key roles. However, both reactions su...

Among lithium battery cathode materials, Li1.2Ni0.13Mn0.54Co0.13O2 (LR-NMC) has a high theoretical capacity, but suffers from voltage and capacity fade during cycling. This is partially ascribed to transition metal cation migration, which involves the local transformation of honeycomb layered structure spinel-like nano-domains. Determination layered/spinel phase ratio powder X-ray diffraction d...

An electron paramagnetic resonance (EPR) investigation on Ti-doped MgAl2O4 spinels has been made in order to study the Ti sites. The study we present here concerns the angular dependencies of the Ti EPR lines and the variations of the EPR spectra due to a modification of the TiO2 content or of the chemical composition from MgAl2O4 to MgAl4O7 and MgAl6O10. In all the studied samples except one, ...

CdCr2O4 is a magnetic compound that crystallizes into what is known as a cubic spinel structure, and the magnetic properties stem from the Cr3+ ions, which form a network of corner-sharing tetrahedra. Despite the presence of relatively strong antiferromagnetic, nearest-neighbor interactions between these ions, the peculiar spatial arrangement of the Cr atoms within the spinel structure actually...