The Experts below are selected from a list of 297 Experts worldwide ranked by ideXlab platform
Jiaming Zheng - One of the best experts on this subject based on the ideXlab platform.
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carbon coating of li4ti5o12 using amphiphilic Carbonaceous Material for improvement of lithium ion battery performance
Journal of Power Sources, 2012Co-Authors: Chengyang Wang, Mingming Chen, Jiuzhou Wang, Jiaming ZhengAbstract:Abstract Carbon coating of fine particles of Li 4 Ti 5 O 12 synthesized under hydrothermal condition is carried out by amphiphilic Carbonaceous Material (ACM) in aqueous solution, followed by carbonization at 800 °C for 2 h. The particles prepared are comprised of highly-crystalline spinel-type Li 4 Ti 5 O 12 with the size in the range of 100–400 nm without any agglomeration, of which surface is uniformly covered by a thin carbon layer. Their electrochemical performance as an anode in lithium-ion batteries is evaluated. The initial discharge capacity of carbon-coated Li 4 Ti 5 O 12 at 20 C rate is 137 mA h g −1 and remains as high as 125 mA h g −1 after 100 cycles (91% retention), exhibiting good rate and cyclic performance. Carbon coating by using ACM as carbon precursor gives the Li 4 Ti 5 O 12 particles an enhanced performance as an anode in lithium-ion batteries, owing to the improvement in electrical conductivity, polarization and ability of dispersion. This non-organic coating process may present a new economic, facile, and green pathway for the preparation of carbon-coated Li 4 Ti 5 O 12 as a high power anode Material in lithium-ion batteries.
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preparation of mesoporous carbons from amphiphilic Carbonaceous Material for high performance electric double layer capacitors
Journal of Power Sources, 2011Co-Authors: Jin Wang, Mingming Chen, Chengyang Wang, Jiuzhou Wang, Jiaming ZhengAbstract:Abstract Amphiphilic Carbonaceous Material (ACM), with nanoscale dispersion in alkaline aqueous solutions, is synthesized from green needle coke. As a special precursor with small particle size, plenty of functional groups and widened d002 simultaneously, ACM guarantees subsequent ACM-based activated carbons (AACs) with high specific surface area over 3000 m2 g−1 as well as well-developed mesoporous structure after KOH activation. Such pore properties enable AACs’ high performances as electrode Materials for electric double-layer capacitors (EDLCs). In particular, surface area up to 3347 m2 g−1 together with notable mesopore proportion (26.9%) gives sample AAC814 outstanding EDLC behaviors during a series of electrochemical tests including galvanostatic charge/discharge, CV and electrochemical impedance spectroscopy. The electrode gets satisfactory gravimetric and volumetric specific capacitance at the current density of 50 mA g−1, up to 348 F g−1 and 162 F cm−3, respectively. Furthermore, for the mesoporosity, there is only a slight capacitance reduction for AAC814 as the current density reaches 1000 mA g−1, indicating its good rate performance. It is all the ACM's unique characteristics that make AACs a sort of competitive EDLC electrode Materials, both in terms of specific capacitance and rate capability.
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amphiphilic Carbonaceous Material modified graphite as anode Material for lithium ion batteries
Materials Letters, 2010Co-Authors: Jin Wang, Mingming Chen, Chengyang Wang, Buqian Hu, Jiaming ZhengAbstract:Abstract Artificial graphite powder was coated by amphiphilic Carbonaceous Material (ACM) in aqueous solutions. SEM and XRD results show that the surface defects and edge sites of original graphite are uniformly covered by the ACM coating layer after modification. The overall characteristics of graphite, however, are not severely changed. Electrochemical measurements were then carried out to evaluate the anode performances of samples in lithium-ion batteries. The modified graphite shows an initial efficiency up to 90.6% and discharge capacitance of 366.4 mAhg− 1. Meanwhile, its capacitance remains as high as 350 mAhg− 1 after 30 cycles charge/discharge tests, evincing good cyclic performance. Compared with conventional methods, the abovementioned non-organic solvent coating presents an economic, facile, and green pathway for graphite mass utilisation as an alternative anode Material in lithium-ion batteries.
C. Fall - One of the best experts on this subject based on the ideXlab platform.
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adsorption of cadmium by na and fe modified zeolitic tuffs and Carbonaceous Material from pyrolyzed sewage sludge
Journal of Environmental Management, 2012Co-Authors: E Gutierrezsegura, M Solacherios, Arturo Colincruz, C. FallAbstract:Abstract In the present study the process of adsorption of cadmium from aqueous solutions using Na-zeolitic tuff, Fe-zeolitic tuff and Carbonaceous Material from pyrolyzed sewage sludge treated with HCl was investigated. The cadmium removal efficiency was studied as a function of contact time, adsorbate concentration, pH and adsorbent dose. The results showed that removal of cadmium was best described by the Langmuir–Freundlich isotherm. The kinetic experimental results were best described by the pseudo-first order model. The results indicate that the adsorption mechanism is physical and chemical sorption on heterogeneous Materials. The maximum retention of cadmium was at pH around 6.0 for the Materials. In kinetic studies, the Na and Fe modified zeolitic tuffs showed similar sorption capacities for cadmium and they were higher than the capacity found for Carbonaceous Material.
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Adsorption of cadmium by Na and Fe modified zeolitic tuffs and Carbonaceous Material from pyrolyzed sewage sludge
Journal of Environmental Management, 2012Co-Authors: E. Gutiérrez-segura, A. Colín-cruz, M. Solache-ríos, C. FallAbstract:In the present study the process of adsorption of cadmium from aqueous solutions using Na-zeolitic tuff, Fe-zeolitic tuff and Carbonaceous Material from pyrolyzed sewage sludge treated with HCl was investigated. The cadmium removal efficiency was studied as a function of contact time, adsorbate concentration, pH and adsorbent dose. The results showed that removal of cadmium was best described by the Langmuir-Freundlich isotherm. The kinetic experimental results were best described by the pseudo-first order model. The results indicate that the adsorption mechanism is physical and chemical sorption on heterogeneous Materials. The maximum retention of cadmium was at pH around 6.0 for the Materials. In kinetic studies, the Na and Fe modified zeolitic tuffs showed similar sorption capacities for cadmium and they were higher than the capacity found for Carbonaceous Material. © 2011 Elsevier Ltd.
Simon Wallis - One of the best experts on this subject based on the ideXlab platform.
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recognition of shear heating on a long lived major fault using raman Carbonaceous Material thermometry implications for strength and displacement history of the mtl sw japan
Island Arc, 2015Co-Authors: Simon Wallis, Koichiro Fujimoto, Hiroshi Mori, Norio ShigematsuAbstract:The extent to which movement on major faults causes long term shear heating is a contentious issue and an important aspect in the debate about the strength of major faults in the crust. Comparing the results of experimental work on the kinetics of crystallization of Carbonaceous Material with results of thermal modeling show that the Raman Carbonaceous Material (CM) geothermometer is well suited to studying shear heating on geological time scales in suitable lithologies exposed around exhumed major fault zones. The Median Tectonic Line (MTL), SW Japan, is the largest on-land fault in Japan with a length of > 800 km. Application of Raman CM thermometry to pelitic schist adjacent to the fault reveals the presence of a rise in peak temperature of around 60 °C over a distance of around 150 m perpendicular to the MTL fault plane. The spatial association of this thermal anomaly with the fault implies it is due to shear heating. Thermal modeling shows the recorded thermal anomaly and steep temperature gradient is compatible with very high rates of displacement over time scales of a few thousand years. However, the implied displacement rates lie outside those generally observed. An alternative explanation is that an originally broader thermal anomaly that developed during strike slip faulting was shortened due to the effects of normal faulting. Constraints on displacement rate, width of the original anomaly, duration of heating and peak temperature imply a coefficient of friction, μ, greater than 0.4.
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Recognition of shear heating on a long‐lived major fault using Raman Carbonaceous Material thermometry: implications for strength and displacement history of the MTL, SW Japan
Island Arc, 2015Co-Authors: Hiroshi Mori, Simon Wallis, Koichiro Fujimoto, Norio ShigematsuAbstract:The extent to which movement on major faults causes long term shear heating is a contentious issue and an important aspect in the debate about the strength of major faults in the crust. Comparing the results of experimental work on the kinetics of crystallization of Carbonaceous Material with results of thermal modeling show that the Raman Carbonaceous Material (CM) geothermometer is well suited to studying shear heating on geological time scales in suitable lithologies exposed around exhumed major fault zones. The Median Tectonic Line (MTL), SW Japan, is the largest on-land fault in Japan with a length of > 800 km. Application of Raman CM thermometry to pelitic schist adjacent to the fault reveals the presence of a rise in peak temperature of around 60 °C over a distance of around 150 m perpendicular to the MTL fault plane. The spatial association of this thermal anomaly with the fault implies it is due to shear heating. Thermal modeling shows the recorded thermal anomaly and steep temperature gradient is compatible with very high rates of displacement over time scales of a few thousand years. However, the implied displacement rates lie outside those generally observed. An alternative explanation is that an originally broader thermal anomaly that developed during strike slip faulting was shortened due to the effects of normal faulting. Constraints on displacement rate, width of the original anomaly, duration of heating and peak temperature imply a coefficient of friction, μ, greater than 0.4.
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a new approach to develop the raman Carbonaceous Material geothermometer for low grade metamorphism using peak width
Island Arc, 2014Co-Authors: Yui Kouketsu, Hiroshi Mori, Mutsuki Aoya, Shunsuke Endo, Tomoyuki Mizukami, Daisuke Nakamura, Hidetoshi Hara, Simon WallisAbstract:The Raman spectra of Carbonaceous Material (CM) from 19 metasediment samples collected from six widely separated areas of Southwest Japan and metamorphosed at temperatures from 165 to 655°C show systematic changes with metamorphic temperature that can be classified into four types: low-grade CM (c. 150–280°C), medium-grade CM (c. 280–400°C), high-grade CM (c. 400–650°C), and well-crystallized graphite (> c. 650°C). The Raman spectra of low-grade CM exhibit features typical of amorphous carbon, in which several disordered bands (D-band) appear in the first-order region. In the Raman spectra of medium-grade CM, the graphite band (G-band) can be recognized and several abrupt changes occur in the trends for several band parameters. The observed changes indicate that CM starts to transform from amorphous carbon to crystallized graphite at around 280°C, and this transformation continues until 400°C. The G-band becomes the most prominent peak at high-grade CM suggesting that the CM structure is close to that of well-crystallized graphite. In the highest temperature sample of 655°C, the Raman spectra of CM show a strong G-band with almost no recognizable D-band, implying the CM grain is well-crystallized graphite. In the Raman spectra of low- to medium-grade CM, comparisons of several band parameters with the known metamorphic temperature show inverse correlations between metamorphic temperature and the full width at half maximum (FWHM) of the D1- and D2-bands. These correlations are calibrated as new Raman CM geothermometers, applicable in the range of c. 150–400°C. Details of the methodology for peak decomposition of Raman spectra from the low to medium temperature range are also discussed with the aim of establishing a robust and user-friendly geothermometer.
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extending the applicability of the raman Carbonaceous Material geothermometer using data from contact metamorphic rocks
Journal of Metamorphic Geology, 2010Co-Authors: Mutsuki Aoya, Yui Kouketsu, Shunsuke Endo, H Shimizu, Tomoyuki Mizukami, Daisuke Nakamura, Simon WallisAbstract:The degree of graphitization of Carbonaceous Material (CM) has been widely used as an indicator of metamorphic grade. Previous work has demonstrated that peak metamorphic temperature (T )o f regional metamorphic rocks can be estimated by an area ratio (R2) of peaks recognized in Raman spectra of CM. The applicability of this method to low-pressure ( 50) that adequately reflects the range of sample heterogeneity. Using this procedure (with 532-nm laser) and adapting our new calibration, the errors of the Raman CM geothermometer for contact metamorphic rocks decrease to � ±30 � C.
Olivier Beyssac - One of the best experts on this subject based on the ideXlab platform.
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provenance analysis using raman spectroscopy of Carbonaceous Material a case study in the southern alps of new zealand
Journal of Geophysical Research, 2015Co-Authors: Lukas Nibourel, Olivier Beyssac, Frederic Herman, Jerome LaveAbstract:Detrital provenance analyses in orogenic settings, in which sediments are collected at the outlet of a catchment, have become an important tool to estimate how erosion varies in space and time. Here we present how Raman Spectroscopy on Carbonaceous Material (RSCM) can be used for provenance analysis. RSCM provides an estimate of the peak temperature (RSCM-T) experienced during metamorphism. We show that we can infer modern erosion patterns in a catchment by combining new measurements on detrital sands with previously acquired bedrock data. We focus on the Whataroa catchment in the Southern Alps of New Zealand and exploit the metamorphic gradient that runs parallel to the main drainage direction. To account for potential sampling biases, we also quantify abrasion properties using flume experiments and measure the total organic carbon content in the bedrock that produced the collected sands. Finally, we integrate these parameters into a mass-conservative model. Our results first demonstrate that RSCM-T can be used for detrital studies. Second, we find that spatial variations in tracer concentration and erosion have a first-order control on the RSCM-T distributions, even though our flume experiments reveal that weak lithologies produce substantially more fine particles than do more durable lithologies. This result implies that sand specimens are good proxies for mapping spatial variations in erosion when the bedrock concentration of the target mineral is quantified. The modeling suggests that highest present-day erosion rates (in Whataroa catchment) are not situated at the range front but around 10 km into the mountain belt.
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Metasomatism and graphite formation at a lithological interface in Malaspina (Alpine Corsica, France)
Contributions to Mineralogy and Petrology, 2013Co-Authors: Matthieu E. Galvez, Olivier Beyssac, Isabelle Martinez, Karim Benzerara, Pierre Agrinier, Nelly AssayagAbstract:Multiple pieces of geologic evidence suggest that interfaces between contrasted lithologies exert a strong control on the fate of volatiles in subduction zones. Here we present results from a contact between serpentinites and sediments, located in Corsica and metamorphosed in the blueschist facies during the alpine orogeny. It was shown previously that carbonates in the sediments have been reduced to graphitic Carbonaceous Material within a 5–10-cm-thick reaction zone at the contact with serpentinites. In an effort to investigate the mechanisms governing this unusual process, bulk rock geochemical analyses incorporating a statistical analysis of compositional data are presented. Observations show that the fate of C was decoupled from that of other elements such as O, H, and large-ion lithophile elements—e.g. K, Sr, Ba...,As—that were extensively leached from the reaction zone. Notably, Na is strongly enriched in the reaction zone and structurally linked to pectolite. Reducing conditions, manifested by the depletion of O in the reaction zone compared to the bulk metasediment, were likely maintained by the presence of Fe(II) in the serpentinite. Moreover, thermodynamic calculations show that the low solubility of carbon in COH fluids at high-pressure and low-temperature conditions was the main driver for graphite precipitation synchronously with carbonate destabilization. This may have been kinetically favored by the presence of already existing graphitized Carbonaceous Material and phengite in the metasediment. Limited lateral flow might have contributed as well to the geochemical and petrological patterns observed in these rocks.
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evolution of the raman spectrum of Carbonaceous Material in low grade metasediments of the glarus alps switzerland
Terra Nova, 2010Co-Authors: A Lahfid, Olivier Beyssac, Christian Chopin, E Deville, F Negro, Bruno GoffeAbstract:Terra Nova, 22, 354–360, 2010 Abstract The Raman spectrum of Carbonaceous Material (CM) from advanced diagenesis (∼200 °C) to low-grade metamorphism (∼320 °C) is documented in the Helvetic flysch of the Glarus Alps (Switzerland). The spectrum is complex, with several defect bands at ∼1200 (D4), ∼1350 (D1), ∼1500 (D3) and ∼1620 (D2) cm−1. We document the evolution of these bands relative to the ‘graphite’ G band with increasing metamorphic grade, and we show that this qualitative evolution may be used as a proxy for temperature in the Glarus Alps. We develop a robust peak-fitting method and propose quantitative parameters that may be used as proxies for thermal metamorphism in this region. Further work in other geological contexts is needed to assess whether the spectral evolution observed in the Glarus Alps may be generalized and to critically assess the potential for calibrating a general, empirical and quantitative thermometer based on the Raman spectrum of CM in low-grade rocks.
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thermal structure of the alboran domain in the rif northern morocco and the western betics southern spain constraints from raman spectroscopy of Carbonaceous Material
Journal of Metamorphic Geology, 2006Co-Authors: F Negro, Olivier Beyssac, Bruno Goffe, Omar Saddiqi, Mohamed BouybaoueneAbstract:In the Rif (northern Morocco) and the Western Betics (southern Spain), the Alboran Domain forms a complex stack of metamorphic nappes including mantle peridotites (Beni Bousera and Ronda). We present in this paper new temperature data obtained in the Alboran Domain based on Raman spectroscopy of Carbonaceous Material (RSCM thermometry). In the lower metamorphic nappes of the Alboran Domain (lower Sebtides–Alpujarrides) temperature ranges from > 640 °C at the base of the metapelitic sequence to 500 °C at the top. The relationships between field isotherms and nappe structure show that peak temperatures were reached during strong ductile thinning of these nappes whereas they partly postdate this main episode in the Rif. In the upper nappes of the Alboran Domain (Ghomarides–Malaguides), generally supposed to be only weakly metamorphosed, temperatures range from ∼500 °C at their base down to < 330 °C at the top. This temperature gradient is consistent with progressive Cenozoic resetting of K–Ar and 40Ar–39Ar ages. These nappes were thus affected by a significant thermal metamorphism, and the available age data in the underlying Sebtides–Alpujarrides show that this metamorphism is related to the metamorphic evolution of the whole Alboran Domain during the Late Oligocene–Early Miocene. Such thermal structure and metamorphic evolution can be explained by generalized extension in the whole Alboran Domain crustal sequence. At a larger scale, the present thermal structure of the Alboran Domain is roughly spatially consistent around the Beni Bousera peridotites in the Rif, but much more affected by late brittle tectonics around the Ronda peridotites in the Western Betics. Therefore, on the basis of the observed thermal structure, the metamorphic evolution of the Alboran Domain can be interpreted as the result of the ascent of hot mantle units contemporaneous with thinning of the whole lithosphere during an Oligo-Miocene extensional event. The resulting structure has however been dismembered by late brittle tectonics in the Western Betics.
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thermal metamorphism in the lesser himalaya of nepal determined from raman spectroscopy of Carbonaceous Material
Earth and Planetary Science Letters, 2004Co-Authors: Olivier Beyssac, Laurent Bollinger, Jean Philippe Avouac, Bruno GoffeAbstract:The determination of metamorphic conditions is critical to the understanding of the formation of mountain belts. However, all collisional mountain belts contain large volumes of accreted sediments generally lacking metamorphic index minerals and are therefore not amenable to conventional petrologic investigations. By contrast, these units are often rich in Carbonaceous Material, making it possible to determine thermal metamorphism through Raman spectroscopy of Carbonaceous Material (RSCM method), a technique that has been recently calibrated [Beyssac et al., J. Metamorph. Geol. 20 (2002) 859–871]. The Lesser Himalaya (LH) is one of these problematic cases with a very poor mineralogy, but a key structural position within the Himalayan system that makes LH considered as diagnostic of the overall thermal behaviour of the orogen. This work demonstrates the performance of the RSCM technique and shows that this technique might thus be used to detect inter-sample variations as small as ~10–15 °C, but absolute temperatures can only be determined to ±50 °C due to the uncertainty on the calibration. This study reveals that the LH has undergone a large-scale thermal metamorphism, with temperature decreasing progressively from about 540 °C at the top to less than 330 °C within the deepest exhumed structural levels.
Arturo Colincruz - One of the best experts on this subject based on the ideXlab platform.
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adsorption of cadmium by na and fe modified zeolitic tuffs and Carbonaceous Material from pyrolyzed sewage sludge
Journal of Environmental Management, 2012Co-Authors: E Gutierrezsegura, M Solacherios, Arturo Colincruz, C. FallAbstract:Abstract In the present study the process of adsorption of cadmium from aqueous solutions using Na-zeolitic tuff, Fe-zeolitic tuff and Carbonaceous Material from pyrolyzed sewage sludge treated with HCl was investigated. The cadmium removal efficiency was studied as a function of contact time, adsorbate concentration, pH and adsorbent dose. The results showed that removal of cadmium was best described by the Langmuir–Freundlich isotherm. The kinetic experimental results were best described by the pseudo-first order model. The results indicate that the adsorption mechanism is physical and chemical sorption on heterogeneous Materials. The maximum retention of cadmium was at pH around 6.0 for the Materials. In kinetic studies, the Na and Fe modified zeolitic tuffs showed similar sorption capacities for cadmium and they were higher than the capacity found for Carbonaceous Material.
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sorption of indigo carmine by a fe zeolitic tuff and Carbonaceous Material from pyrolyzed sewage sludge
Journal of Hazardous Materials, 2009Co-Authors: E Gutierrezsegura, M Solacherios, Arturo ColincruzAbstract:Abstract Indigo carmine removal from aqueous solution has been evaluated using Fe-zeolitic tuff and Carbonaceous Material from pyrolyzed sewage sludge treated with HCl (CM). The adsorbents were characterized by scanning electron microscopy, BET surface area and X-ray diffraction. Sorption kinetics and isotherms were determined and the adsorption behaviors analyzed. Kinetic pseudo-second order and Langmuir–Freundlich models were successfully applied to the experimental results obtained with the Fe-zeolitic Material, while kinetic first order and Langmuir–Freundlich models were applied to the results from the Carbonaceous Materials. This indicates mechanisms of chemisorption and physic sorption, respectively, on the heterogeneous Materials. The results indicate that the Carbonaceous Material from the pyrolysis of sewage sludge (sorption capacity 92.83 mg/g) is a better adsorbent of indigo carmine than the zeolitic Material (sorption capacity 32.83 mg/g).
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sorption and desorption of dye remazol yellow onto a mexican surfactant modified clinoptilolite rich tuff and a Carbonaceous Material from pyrolysis of sewage sludge
Water Air and Soil Pollution, 2007Co-Authors: J Torresperez, M Solacherios, Arturo ColincruzAbstract:The sorption behavior of dye remazol yellow using surfactant modified zeolitic rock and a Carbonaceous Material obtained by pyrolysis of sewage sludge and treated with HCl (1.0%) solution was determined. The kinetic and sorption isotherms experimental results were best adjusted to the pseudo-second order model and to the Langmuir-Freundlich isotherm model which indicate that the sorption process is chemisorption on heterogeneous Materials. Remazol yellow could be removed from the saturated modified zeolitic Material by different processes, unfortunately, the surfactant was removed together with the dye, the best results were found using Fenton's reagent. Thermal treatment was the best method found to remove the dye from the Carbonaceous Material.