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Showing 1 to 20 of 29 for “"olivines"”.
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Aspects of transformation behaviour in olivines, pyroxenes and titanomagnetites
… of materials. TEM observations made on shocked olivines and pyroxenes show that a number of the assumptions made in the application of the results of experimental studies of shock-induced phase transformations are incorrect. TEM studies of titanomagnetites have also shown that the interpretation …
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First-principles investigation of Li intercalation kinetics in phospho-olivines
… the Li intercalation mechanism in phospho-olivines, namely LiFePO₄ and Li(Fe,Mn)PO₄, using first-principles calculations. Currently Li-ion battery technology is critically relied upon for the operation of electrified vehicles, but further improvements mainly in cathode performance are …
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Distribution of trace elements in olivines and proxenes - an experimental study
"Olivine, pyroxene,and spinel were crystallized in the ternary system anorthite-forsterite-silica to which trace amounts of the transition metal ions Cr³⁺, Fe²⁺, Mn²⁺, Co²⁺, Ni²⁺, and Cu²⁺ had been added. The resulting concentrations of the transition metal ions in the liquid and crystalline phases …
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Cell parameter systematics of the binary silicate olivines: methods for the determination of composition and intracrystalline cation ordering
… Ni-Fe, Mg-Mn, and Mg-, Fe-, and Mn-Ca binary olivines, using data from the literature. The resulting regression equations are given below. The coefficients of correlation exceed 0.997 in all cases. Fe-Mn binary olivines a= 3.527 + 1.341rM1 + 0.317rM2 b = 8.586 - 1.856rM1 + 4.281rM2 Mg-Mn …
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The geochemistry of the Olivine Melilitetes and related rocks of Namaqualand Bushmanland, South Africa
… pipes studied: (a) Rare anhedral or subhedral olivines that display marked disequilibrium features with the surrounding matrix and which are characterized by having high iron and extremely low nickel contents (referred to as HILN olivines) relative to the remaining olivines in the same rock; …
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A TEM study of crystalline silicates in the matrices of MET 00426 and QUE 99177 CR3.0 chondrites: Constraints on the formation mechanisms of dust in the solar nebula
… These grains are MgO-rich or FeO-bearing olivines and pyroxenes. These crystalline silicates exhibit unequilibrated major and minor element compositions, but distinct compositional groupings of olivines and pyroxenes can be identified. We infer that the crystalline silicate materials in …
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Phase behavior and phase transformation kinetics during electrochemical cycling of lithium transition metal olivine compounds
… studies have attributed the rate capability of olivines purely to chemical diffusion limitations. Many efforts have been devoted to improving the conductivity and the rate performance of LiFePO4 cathodes. Since this class of olivines undergoes a first-order phase transition upon electrochemical …
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Electrochemically-induced phase transition in olivine type cathode materials
… Using olivine-type phosphates (i.e. phospho-olivines) with varying composition and particle size as model system, strain accommodation mechanism within single nanoparticles (Chapter 2 to 3) and mesoscale kinetics of nanoparticle aggregates (Chapter 4 to 5) during electrochemically-induced …
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Petrogenesis of the Eshowe melilitites
… complex zonation patterns had developed on the olivines. The microphenocryst olivines are believed to be the only population of grains that crystallised from the Emtilombo 'parental magma'. Mode of emplacement of the melilitites is probably influenced by the nature and volume of magma in the …
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The petrogenesis and geochemistry of the Namaqualand olivine melilitite pipe cluster, western South Africa
… ratios of olivine separates indicate that olivines from a large majority of the melilitite pipes have compositions indistinguishable from those from typical upper mantle peridotite (4.9-5.2‰). However, three melilitite pipes emplaced within the mid-Cretaceous Koegel Fontein igneous complex …
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Synthesis and electrochemical characterization of lithium vanadium phosphate
… which LVP is a part of, indicate that the olivines have high lithium diffusivity but low electronic conductivity. LVP is part of the phosphor- olivine family, which traditionally has been shown to have high lithium diffusivity but low electronic conductivity. LVP was synthesized via a …
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Oxygen isotope composition of megacrysts from the Monastery kimberlite
… the δ 18O value and Mg# and Cr#. The Fe-rich olivines show positive correlations with Mg# and Ni. The phlogopites show no correlations with the major element compositions. The Group 3 ilmenites have δ18O values ranging from 2.93-4.05‰ (x̄ = 3.59‰, σ = 0.36, n = 7). These are below the δ18O …
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Electrochemically driven phase transformation in energy storage compounds
Nanoscale lithium transition metal phosphate olivines have become commercially important as positive electrode materials in a new generation of lithium-ion batteries. Not surprisingly, many energy storage compounds undergo phase transitions in-situ, including the production of metastable phases. …
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The evolution of oceanic gabbros : in-situ and ancient examples
… that are more primitive than plagioclases and olivines with which they coexist. Melt-rock interaction, where ascending melts dissolve the pre-existing gabbroic rocks and create hybrid magma may have caused this. Dissolution-experiments for plagioclase-olivine and plagioclase-augite mineral pairs
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Experimental investigation into lunar melt density and compressibility : the role of titanium
… between these melts and their equilibrium olivines and pyroxenes, and show that these glasses, with the exception of A17O, should be able to rise to the surface as a result of buoyancy forces alone. For the eruption of A17O, we must call upon the rising diapir model of Hess (1991) to …
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Deciphering the Tectonics of the Caucasus from Post-Collisional Volcanism
… compositions. High Mg# cores (>85) of olivines suggest significant fractionation has occurred. Trace element patterns show a distinctive supra-subduction setting, suggesting the fluid-enriched source remained in place, and hydrated >10 Ma following collision. Isotope ratios require an …
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Microanalytical Constraints on the Geometry and Chemical Evolution of Kīlauea’s Volcanic Plumbing System
… 5 shows that relatively primitive Kīlauean olivines and their melt inclusions are out of major and trace element equilibrium with their carrier melts, with broad-reaching implications for the interpretation of melt inclusion records in mush-rich volcanic systems. Specifically, this work …
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Evolution of oceanic gabbros : in-situ and ancient examples
… that are more primitive than plagioclases and olivines with which they coexist. Melt-rock interaction, where ascending melts dissolve the pre-existing gabbroic rocks and create hybrid magma may have caused this. Dissolution-experiments for plagioclase-olivine and plagioclase-augite mineral …
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Point Defects And Defect-Related Transport Of Matter In Transition Metal-Containing Orthosilicates
… the transport properties of sufficiently pure olivines are governed by point defects. To improve the currently limited understanding of the defect structure and defect-related transport properties of olivine group compounds, the transport of matter in orthosilicates of the type Me2SiO4, with Me …
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MICROSTRUCTURAL CONSTRAINTS ON THE FORMATIONAL AND THERMAL HISTORIES OF REFRACTORY INCLUSIONS IN CO3 CHONDRITES
… margins of AOAs and along grain boundaries of olivines in AOAs provide evidence that mild parent body thermal metamorphism occurred at relatively low temperatures. However, due to incomplete textural and chemical equilibration of the whole rock, Kainsaz AOAs still retain primary nebular …
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