Minor element variations in MgAl2O4 spinel from the type B1 calcium-aluminum-rich inclusion (CAI) Allende TS-34 confirm earlier studies in showing correlations between the minor element chemistry of spinels with their location within the inclusion and with the chemistry of host silicate phases. These correlations result from a combination of crystallization of a liquid produced by re-melting ev...

[1] We present details of the identification of sites that show an absorption band at visible wavelengths and a strong 2 m band using the SELENE Spectral Profiler. All the sites exhibiting the visible feature are found on the regional dark mantle deposit (DMD) at Sinus Aestuum. All the instances of the visible feature show a strong 2 m band, suggestive of Feand Cr-rich spinels, which are differ...

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 ...

Spinel-type oxides are technologically important in many fields, including electronics, magnetism, catalysis and electrochemical energy storage and conversion. Typically, these materials are prepared by conventional ceramic routes that are energy consuming and offer limited control over shape and size. Moreover, for mixed-metal oxide spinels (for example, Co(x)Mn(3-x)O4), the crystallographic p...

Low-temperature structures of the lithium manganese spinels were determined using TOF neutron Rietveld analysis. The spinels LiMn2O4 with different values, (0.016, 0.040, and 0.132) showed the cubic-orthorhombic phase transitions, and the lattice distortion decreased with decreasing . Although no anomaly corresponding to the cubic-orthorhombic phase transition was observed in the DSC curve for ...

MIn2S4 (M = Mn, Cd, Mg) spinels were investigated by Raman scattering spectroscopy under hydrostatic pressure up to 20 GPa. These compounds were found to undergo a reversible phase transition to a Raman-inactive defect NaCl-type structure. Transition pressures of 7.2, 9.3, and 12 GPa were found for M = Mn, Cd, and Mg, respectively. From the analysis of the pressure behaviour of Raman-active mod...

Technetium ((99)Tc) is an abundant, long-lived radioactive fission product whose mobility in the subsurface is largely governed by its oxidation state. Tc immobilization is crucial for radioactive waste management and environmental remediation. Tc(IV) incorporation in spinels has been proposed as a novel method to increase Tc retention in glass waste forms during vitrification. However, experim...

This dissertation reports on the synthesis, structural and thermal characterization and electrical and thermal transport properties of a variety of strongly correlated spinels. General structure property relationships for electrical and thermal transport are discussed. However, the relationship between thermopower and features of the crystal structure such as spin, crystal field, anti-site diso...