190 research outputs found
Embodiment, relation, community: a continental philosophy of communication/ Garnet C. Butchart.
No full textIncludes bibliographical references and index."Integrates the perspectives of Giorgio Agamben, Roberto Esposito, Jean-Luc Nancy, and Lacanian psychoanalysis to distinguish communication theory from the philosophy of communication"--Provided by publisher.The wager of communication (as revealed by psychoanalysis) -- The ban of language and law of communication -- Of communication and-as immunization -- Body as index -- What remains to be thought : community, or being-with.1 online resource (199 pages
Phase relationships in grunerite-garnet-bearing amphibolites in the systemCFMASH, with applications to metamorphic rocks from the Central Zone of the Limpopo Belt, South Africa.
No full textA petrogenetic grid in the model system CaO–FeO–MgO–Al2O3–SiO2–H2O is presented, illustrating the phase relationships among the minerals grunerite, hornblende, garnet, clinopyroxene, chlorite, olivine, anorthite, zoisite and aluminosilicates, with quartz and H2O in excess. The grid was calculated with the computer softwarethermocalc, using an upgraded version of the internally consistent thermodynamic dataset HP98 and non-ideal mixing activity models for all solid solutions. From this grid, quantitative phase diagrams (P–T pseudosections) are derived and employed to infer a P–T path for grunerite–garnet-bearing amphibolites from the Endora Klippe, part of the Venetia Klippen Complex within the Central Zone of the Limpopo Belt. Agreement between calculated and observed mineral assemblages and garnet zonation indicates that this part of the Central Zone underwent a prograde temperature and pressure increase from c. 540 °C/4.5 kbar to 650 °C/6.5 kbar, followed by a post-peak metamorphic pressure decrease. The inferred P–T path supports a geotectonic model suggesting that the area surrounding the Venetia kimberlite pipes represents the amphibolite-facies roof zone of migmatitic gneisses and granulites that occur widely within the Central Zone. In addition, the P–T path conforms to an interpretation that the Proterozoic evolution of the Central Zone was controlled by horizontal tectonics, causing stacking and differential heating at c. 2.0 Ga
A window into the Early to mid-Cretaceous infrastructure of the Yukon-Tanana terrane recorded in multi-stage garnet of west-central Yukon, Canada
No full textAmphibolite facies metasedimentary schists within the Yukon-Tanana terrane in the northern Canadian Cordillera reveal a two-stage, polymetamorphic garnet growth history. In situ U-Th-Pb Sensitive High Resolution Ion Microprobe dating of monazite provide timing constraints for the late stages of garnet growth, deformation and subsequent decompression. Distinct textural and chemical growth zoning domains, separated by a large chemical discontinuity, reveal two stages of garnet growth characterized in part by: (i) a syn-kinematic, inclusion-rich stage-1 garnet core; and (ii) an inclusion-poor, stage-2 garnet rim that crystallized with syn- to post-kinematic staurolite and kyanite. Phase equilibria modelling of garnet molar and compositional isopleths suggest stage-1 garnet growth initiated at ~600 °C, 8 kbar along a clockwise P-T path. Growth of the compositionally distinct, grossular-rich, pyrope-poor inner portion of the stage-2 overgrowth is interpreted to have initiated at higher pressure and/or lower temperature than the stage-1 core along a separate P-T loop, culminating at peak P-T conditions of ~650-680 °C and 9 kbar. Stage-2 metamorphism and the waning development of a composite transposition foliation ( ST) are dated at c. 118 Ma from monazite aligned parallel to ST, and inclusions in syn- to post- ST staurolite and kyanite. Slightly younger ages ( c. 112 Ma) are obtained from Y-rich monazite that occurs within resorbed areas of both stage-1 and stage-2 garnet, together with retrograde staurolite and plagioclase. The younger ages obtained from these texturally and chemically distinct grains are interpreted, with the aid of phase equilibria calculations, to date the growth of monazite from the breakdown of garnet during decompression at c. 112 Ma. Evidence for continued near-isothermal decompression is provided by the presence of retrograde sillimanite, and cordierite after staurolite, which indicates decompression below ~4-5 kbar prior to cooling below ~550 °C. As most other parts of the Yukon-Tanana terrane were exhumed to upper crustal levels in the Early Jurassic, these data suggest this domain represents a tectonic window revealing a much younger, high-grade tectono-metamorphic core (infrastructure) within the northern Cordilleran orogen. This window may be akin to extensional core complexes identified in east-central Alaska and in the southeastern Canadian Cordillera. [ABSTRACT FROM AUTHOR]Peer reviewedFinal article publishedin situ monazite geochronologyYukon‐Tanana terraneSHRIMPP–T–t pathmulti‐stage garne
Lithium halide coating as an effective intergrain engineering for garnet-type solid electrolytes avoiding high temperature sintering
No full textGarnet-type Li7La3Zr2O12 solid electrolytes were commonly prepared by two steps solid-state reaction method, which undergoes high temperature over 1000 °C and thus inevitable for lithium volatilization and formation of secondary phases. Here, we propose a new intergrain architecture engineering of a solution method, to avoid high temperature sintering for preparing lithium halide (LiX) coated garnet-type solid electrolytes, which contain Al and Ta co-doped Li7La3Zr2O12 (Li6.75La3Zr1.75Ta0.25O12, LLZTO) synthesized at 900 °C with cubic structure. Owing to the increased relative density, the improved formability, and the altered ion transport mode from point to face conduction by LiX coating on LLZTO grains, LiX-coated LLZTO samples demonstrate a good Li dendrite suppression ability and a high ionic conductivity that is three orders of magnitude higher than pristine LLZTO. In another way, this result demonstrates the critical role of the grain boundaries on the ion transport for oxide superionic conductors. The present coating method provides a new strategy to prepare brittle solid electrolytes avoiding high temperature sintering.Accepted Author ManuscriptRST/Storage of Electrochemical Energ
Classroom Projects as Embodied and Embedded Outcomes Assessment
Get PDFAlthough educators already recognize the value in engaging student learning through classroom projects and service-learning, assessment of student learning through classroom projects may be accompanied by a shift of attention from mastery of ideas to embodied knowledge. We argue that embodiment is the basic semiotic condition of being human—of being both an expressive and perceptive (communicative) being among others. Linking this philosophy of communication principle to the topic of assessment, the article offers assessment research a focus of attention on learning settings: from embodiment as learning context, to the built environment of classrooms, as well as to group interaction. We describe assessment of student understanding, demonstrated by way of professional comportment, of communication as a reflexive and reversible relation. Attention to embodied learning encourages habits of being-before and being-with others in the shared world in a reflexive and co-creative manner
EXPERIMENTAL-DETERMINATION OF FE AND MG EXCHANGE BETWEEN GARNET AND OLIVINE AND ESTIMATION OF FE-MG MIXING PROPERTIES IN GARNET
No full textThe partitioning of Fe and Mg between garnet and olivine has been determined as a function of Fe/Mg ratio at 1000°C and 9.1 kbar. Garnets of composition XgtFe = 0.90, 0.82, 0.60, 0.51, and 0.35 were mixed with olivines of various compositions in a ratio of 10:1 by mass, and the equilibrium olivine composition was determined within narrow limits. The magnitudes of the garnet interaction parameters are highly correlated with those of the olivine solution. However, assuming WolFeMg = WolMgFe = 9000 J/mol (two-site basis), we obtain WgtFeMg 2080 ± 1250 J/mol and WgtMgFe = 6350 ± 880 J/mol (three-site basis) at 1000°C. The standard-state free-energy change of the exchange reaction is calculated to be -2000 ± 800 J at 1000°C and 1 bar, in agreement with recent estimates of the free energy of almandine. -from Author
Trigger of the Highly Resistive Layer Formation at the Cathode-Electrolyte Interface in All-Solid-State Lithium Batteries Using a Garnet-Type Lithium-Ion Conductor
No full textInterfacial materials design is critical in the development of all-solid-state lithium batteries. We must develop an electrode-electrolyte interface with low resistance and effectively utilize the energy stored in the battery system. Here, we investigated the highly resistive layer formation process at the interface of a layered cathode: LiCoO2, and a garnet-type solid-state electrolyte: Li6.4La3Zr1.4Ta0.6O12, during the cosintering process using in situ/ex situ high-temperature X-ray diffraction. The onset temperature of the reaction between a lithium-deficient LixCoO2 and Li6.4La3Zr1.4Ta0.6O12 is 60 degrees C, while a stoichiometric LiCoO2 does not show any reaction up to 900 degrees C. The chemical potential gap of lithium first triggers the lithium migration from the garnet phase to the LixCoO2 below 200 degrees C. The lithium-extracted garnet gradually decomposes around 200 degrees C and mostly disappears at 500 degrees C. Since the interdiffusion of the transition metal is not observed below 500 degrees C, the early-stage reaction product is the decomposed lithium-deficient garnet phase. Electrochemical impedance spectroscopy results showed that the highly resistive layer is formed even below 200 degrees C. The present work offers that the origin of the highly resistive layer formation is triggered by lithium migration at the solid-solid interface and decomposition of the lithium-deficient garnet phase. We must prevent spontaneous lithium migration at the cathode-electrolyte interface to avoid a highly resistive layer formation. Our results show that the lithium chemical potential gap should be the critical parameter for designing an ideal solid-solid interface for all-solid-state battery applications
Crystallisation of metamorphic garnet: mechanisms and rates from the inverted Barrovian sequence in the Sikkim Himalaya
No full textThe compositional zonation, three-dimensional spatial distribution, and morphologies of a metamorphic garnet population represent an integrated record of the population's nucleation and growth history over changing metamorphic conditions. While previous inferences drawn from such datasets have proven diverse, their continued collection is key to better understanding the mechanisms and processes that control porphyroblast crystallisation, rates of intergranular element transfer, and the extent to which chemical equilibrium persists across a rock volume during metamorphism. This thesis utilises such datasets from the inverted Barrovian metamorphic sequence in the Sikkim Himalaya, India, where the record of recent orogenesis provides an ideal natural laboratory in which fundamental rock-forming processes can be investigated.Compositional analyses of a representative population of garnet porphyroblasts from a garnet-grade metapelite indicate a strong correlation between garnet crystal size and composition with respect to both major end-member and trace element components. Numerical simulation of progressive nucleation and growth using an equilibrium approach and multicomponent diffusion reproduces the sizes and major element zoning of the entire garnet population along a rapid heating trajectory (>100 C/Myr). Given the correspondingly rapid rates of garnet growth (~1.4 mm/My) and negligible departure from equilibrium, major element transport is inferred to have been non-limiting, with growth rates controlled by interfacial processes.In contrast, trace element zoning in the same population is indicative of persistent disequilibrium with respect to rare-earth elements, yttrium and chromium. Oscillatory zoning may reflect incorporation of chemical heterogeneities and minor fluctuations in the garnet growth rate not resolvable in major element zoning, and annuli are not demonstrably relatable to some rock-wide event. Elements that do not equilibrate across garnet surfaces document continuous spiral zoning, which permits estimation of syn-crystallisation strain-rates, on the order of 10^-11-10^-12 /s.Microstructural data from across the Barrovian sequence reveal garnet populations that are partially characterised by their grade, with changing crystal size and abundance interpreted to reflect the combined effects of bulk chemical variations and ripening with increasing pressures and temperatures. Deviations from this trend reflect populations in which garnet crystallisation was controlled by a highly heterogeneous spatial distribution of nucleation sites and transport-limited growth
Electrochemical performance of a garnet solid electrolyte based lithium metal battery with interface modification
Get PDFGarnet-type Li7La3Zr2O12 solid electrolyte is a promising candidate for all-solid-state batteries owing to its high lithium ion conductivity (up to 10(-3) S cm(-1)) and chemical stability when in contact with the lithium metal with a wide electrochemical window of 6 V. However, the realization still remains elusive mainly due to the high resistance of the electrode/electrolyte interface at room temperature. Although significant improvements have been made toward accomplishing an effective Li metal parallel to garnet solid electrolyte interface, the cathode parallel to garnet solid electrolyte interface is challenging due to the rigid morphology of the garnet solid electrolyte, and poor conductivity and chemical instability of the cathode materials. Herein we report an effective strategy of lowering the interfacial resistance between LiNi0.33Mn0.33Co0.33O2 (NMC) and Li6.28La3Zr2Al0.24O12 (LLZA) solid electrolytes with a Li2SiO3 (LS) interlayer. The investigation of the NMC parallel to LS-LLZA interface by SEM, adherence test and electrochemical symmetric cell measurement (NMC parallel to LS-LLZA-LS parallel to NMC) revealed that a liquid phase derived Li2SiO3 buffer layer, not only improves the wettability, but also assists the lithium ion conduction to the active material. On the basis of this improved interface, a bulk type all-solid-state and a quasi-solid-state (using a gel polymer electrolyte at the Li parallel to LLZA interface) lithium metal batteries were fabricated with initial discharge capacities of 138 mA h g(-1) (100 degrees C) and 165 mA h g(-1) (25 degrees C) at 10 mA cm(-2) and 100 mA cm(-2) , respectively. The quasi-solid-state battery (NMC parallel to LS-LLZA parallel to GPE parallel to Li) at room temperature displays a capacity retention of 87% over 50 cycles at a higher current density of 100 mA cm(-2)
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