Thermochemical and compressibility data are used to calculate the approximate pressures and temperatures required for the reaction of clinoenstatite to Mg•SiO• (spinel or olivine) or to periclase and stishovite, the reaction of forsteritc to Mg•SiO• (spinel) or periclase and stishovite, and the breakdown of Mg•SiO• (spinel) to periclase and stishovite. The calculated reaction lines for Mg•SiO• ...

This book chapter is organized into four major parts. Firstly, it will cover an introduction of using spinel ferrite nanoparticles in biomedical applications, including the antibacterial properties. The second part will provide an overview of the structure and magnetism of spinel ferrites. The third part will focus on the preparation of cobalt ferrite and transition metal substituted cobalt fer...

Samples of nickel cobaltite, a mixed oxide occurring in the spinel structure which is currently extensively investigated because of its prospective application as ferromagnetic, electrocatalytic, and cost-effective energy storage material were prepared in the form of nanocrystals stabilized in a highly porous silica aerogel and as unsupported nanoparticles. Nickel cobaltite nanocrystals with av...

Ordered mesoporous Fe(3)O(4) with crystalline walls (inverse spinel structure) has been synthesized for the first time, representing to the best of our knowledge, the first synthesis of a reduced mesoporous iron oxide. Synthesis was achieved by reducing ordered mesoporous alpha-Fe(2)O(3) (corundum structure) to Fe(3)O(4) spinel then to gamma-Fe(2)O(3) by oxidation, while preserving the ordered ...

Geologists usually deal with rocks that are up to several thousand million years old. They try to reconstruct the tectonic settings where these rocks were formed and the history of events that affected them through the geological time. The spinel group minerals provide useful information regarding the geological environment in which the host rocks were formed. They constitute excellent indicato...

Two Cu-Co and Co3O4 oxides were synthesized by the conventional sol-gel auto-combustion and their physical-chemical properties were characterized by XRD, FTIR, SEM, TPR and XPS. The XRD results indicated that copper-cobalt oxide appeared in a mixture form of Cu0.15Co2.85O4 spinel and CuO phases, whereas the cobalt oxide exhibited in the pure form of Co3O4 spinel. The FTIR approved the formation...

Quaternary compounds AB 2 X 3 Y (A = Cu, Ag ; B = In ; X = S, Se, Te ; Y = Cl, Br, I) could be synthesized at high pressures and temperatures. The crystal structures found are defect-zincblende (AgIn2Se3l, AgIn2Te3l, CuIn2Se3Br, CuIn2Se3I, CuIn2Te3Cl, CuIn2Te3Br, CuInTesI), spinel (AgIn2S3Cl, AgIn2S3Br, AgIn2Se3Cl, AgIn2Se3Br, AgIn2Se3l) and defectrocksalt (AgIn2Te3Cl, AgIn2Te3Br). A second for...

The influence of prolonged ball milling on structural changes of hexagonal and spinel type complex iron oxides has been studied by x-ray diffraction and high resolution electron microscopy. The XRD and HREM results for ball milled SrFel2Olg ferrite show fast decomposition and formation of Fe203 and SrO simple oxides. Microstructural developments for a powder mixture of Co(OH)2 and Fe203 show th...

A high-pressure polymorph of chromite, the first natural sample with the calcium ferrite structure, has been discovered in the shock veins of the Suizhou meteorite. Synchrotron x-ray diffraction analyses reveal an orthorhombic CaFe2O4-type (CF) structure. The unit-cell parameters are a = 8.954(7) A, b = 2.986(2) A, c = 9.891(7) A, V = 264.5(4) A3 (Z = 4) with space group Pnma. The new phase has...

Compact Type A (CTA) inclusions are extremely melilite-rich (typically ~90 vol%), with moderate amounts of spinel and minor fassaite and perovskite. Because CTAs are one of the major types of coarsegrained inclusions found in CV3 chondrites but have not been thoroughly studied as a group, we have undertaken a comprehensive petrographic, mineralchemical, and trace element study of a large suite ...