Natural peridotite samples containing olivine, orthopyroxene, and spinel can be used to assess the oxygen fugacity ( fO2) of the upper mantle. The calculation requires accurate and precise quantification of spinel Fe3+/SFe ratios. Wood and Virgo (1989) presented a correction procedure for electron microprobe (EPMA) measurements of spinel Fe3+/SFe ratios that relies on a reported correlation bet...

The interaction of solid-solid phase transitions with convection in the Earth’s mantle involves, for univariant systems: (1) effects of latent heat and advection of ambient temperature on the position of the phase boundary and on its associated body force, and (2) the coupling of latent heat with the ordinary thermal expansivity of the material. For divariant systems, an effective thermal expan...

LiMn2O4 spinel is an attractive compound as a cathode material in lithium-ion batteries, due to its economical, environment, and safety advantages over LiCoO2. LiMn2O4 adopts the spinel structure with the space group Fd3 hm, in which the Li and Mn occupy the 8a tetrahedral and 16d octahedral sites of the cubic close-packed oxygen ions framework, respectively. However, LiMn2O4 tends to exhibit c...

Nickel-rich cathode materials have attracted widespread interest due to their high capacity; however, the structure is prone degradation and collapse during cycling, resulting in poor stability performance safety, hindering development of high-nickel materials. Here, we propose a straightforward method consume oxygen on surface primary particles high-temperature calcination process precursors, ...

Introduction: Wark-Lovering (WL) rims [1] surrounding many refractory inclusions represent marker events in the early evolution of the Solar System in which many inclusions were exposed to changes in pressure [2], temperature [3], and isotopic reservoirs [4-7]. The effects of these events can be complex, not only producing mineralogical variability of WL rims [2], but also leading to mineralogi...

When highly divided spinel fenites become reactive enough with oxygen, to allow the oxidation of the Fe ions at low temperature and of substitute cations too, when these cations are capable of different valence states. We prepared fine particles of spinel ferrites substituted by Mn, Mo, Cu, by "chimie douce", especially from oxalate precursors and used them to reveal and to study the oxido-redu...

Silicon micromachined calorimeters ("calorimeter on a chip") are used to measure heat capacities and phase transition enthalpies for thin film, single crystal, and powder samples (5-500 mug). The technology is thus compatible with the small samples produced in multianvil and large diamond anvil cells. Techniques for handling small samples and attaching them to the calorimetric devices have been...