Spinels are compounds that have the general formula AB2O4 where A and B are metallic cations. The formal charges of A and B are strictly specifi ed and they are a criterion of the spinel type. There are three types of spinel compounds, the so-called 2-3, 4-2 and 6-1 spinels, where the numbers indicate the formal charges of the cations. The fi rst cation of each pair occupies a tetrahedral site ...

Solid-state compatibility and melting relationships in the subsystem Al2O3–MgAl2O4–CaAl4O7 were studied by firing and quenching selected samples located in the isopletal section (CaOzMgO)–Al2O3. The samples then were examined using X-ray diffractomtery, optical microscopy, and scanning and transmission electron microscopies with wavelengthand energy-dispersive spectroscopies, respectively. The ...

We have deposited the MgAl2O4 thin ®lms on Si(1 0 0) substrates in the temperature range of 270 6008C using newly developed single molecular precursors of Mg[(m-OBu)2AlMe2]2 and Mg[Al(O Bu)4]2 by MOCVD. Polycrystalline, crack-free stoichiometric MgAl2O4 thin ®lms were successfully grown on at as low as 4008C. This growth temperature was much lower than that of conventional CVD, and this is the ...

Introduction: Amoeboid olivine aggregates (AOA) are irregularly shaped inclusions found within all carbonaceous chondrites except CI [1,2]. Their bulk compositions are intermediate between those of anorthite-rich (Type C) calcium-aluminium rich inclusions and chondrules [2], and consist mostly of fine-grained olivine plus enclosed refractory nodules of spinel, pyroxene, feldspathoids, Fe-Ni met...

Plasma-catalytic ammonia synthesis in a dielectric barrier discharge reactor has emerged as possible route for electrification of nitrogen fixation. In this study, we use combination experiments and plasma kinetic model to investigate the from N2 H2, both with without solid packing material zone. The effect power, feed flow rate, N2:H2 ratio, gas residence time, temperature, (MgAl2O4 alone or i...

We report here experimental results of yield strength and stress relaxation measurements of transparent MgAl2O4 nano-ceramics at high pressure and temperature. During compression at ambient temperature, the differential strain deduced from peak broadening increased significantly with pressure up to 2 GPa, with no clear indication of strain saturation. However, by then, warming the sample above ...

Stabilization efficiencies of spinel-based construction ceramics incorporating simulated nickel-laden waste sludge were evaluated and the leaching behavior of products investigated. To simulate the process of immobilization, nickel oxide was mixed alternatively with gamma-alumina, kaolinite, and hematite. These tailoring precursors are commonly used to prepare construction ceramics in the build...

Introduction: Extraterrestrial spinel is a magnetic mineral that is found in melted micrometeorites, in the fusion crust of meteorites and meteoroid ablation droplets, and in various impact-derived spherules more or less preserved in marine sediments. This mineral can be distinguished from terrestrial spinel on the basis of high Ni content and a high ferric/ferrous ratio resulting from crystall...