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中国科学院地质与地球物理研究所2012年度（第12届）学术年会

作者： CHUNXIA ZHANG GREIG A.PATERSON QINGSONG LIU State Key Laboratory of Lithospheric Evolution Institute of Geology and GeophysicsChinese Academy of Sciences Key Laboratory of Cenozoic Geology and Environment Institute of Geology and Geophysics Chinese Academy of Sciences State Key Laboratory of Lithospheric Evolution

The magnetic properties of loess,lake,and ocean sediments are often used as indicators for paleoclimatic/paleoenvironmental *** analysis is a conventional approach for identifying magnetic phases and thermal alteration of *** concentration parameters are often enhanced after thermal treatment. In this study,the role of clay minerals in magnetic enhancement at elevated temperatures is systematically *** results indicate that the clay minerals(saponite, Ca-montmorillonite,kaolinite,and chlorite) are dominated by paramagnetic behaviour and that the magnetic properties remain relatively stable after heating to 700℃in argon. In contrast,mixtures of hematite and chlorite,have a high degree of magnetic enhancement after heating in argon,which indicates that clay minerals play important role in magnetic *** results improve our understanding of the processes involved in complicated mineral transformations,which is important for retrieving paleoclimatic/paleoenvironemntal signals from magnetic proxies.

关键词： clay minerals saponite montmorillonite kaolinite chlorite magnetic enhancement hematite thermomagnetic analysis

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Unveiling the intrinsic properties of single NiZnFeO_x entity for promoting electrocatalytic oxygen evolution

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Chinese Chemical Letters 2024年第4期35卷 181-186页

作者： Zhihao Gu Jiabo Le Hehe Wei Zehui Sun Mahmoud Elsayed Hafez Wei Ma Key Laboratory for Advanced Materials and Joint International Research Laboratory of Precision Chemistry and Molecular Engineering Feringa Nobel Prize Scientist Joint Research CenterFrontiers Science Center for Materiobiology and Dynamic ChemistrySchool of Chemistry and Molecular EngineeringEast China University of Science and TechnologyShanghai 200237China Ningbo Institute of Materials Technology and Engineering Chinese Academy of SciencesNingbo 315201China Department of Chemistry Faculty of ScienceBeni-Suef UniversityBeni-Suef 62511Egypt

Although considerable research efforts have been devoted to the design and development of non-noble electrocatalysts for oxygen evolution reaction(OER), substantial enhancement of OER performance with commercial-scale water electrolysis remains a big challenge. This could result from the difficulties in detecting the intrinsic properties and overlooking the assembly process for electrochemical OER process. Here, we employ a microjet collision method to investigate the intrinsic OER activities of individual NiZnFeO_x entities with and without a moderate magnetic field. Our results demonstrate that single NiZnFeO_x nanoparticles(NPs) show the excellent OER performance with a lowest onset potential(~1.35 V vs. RHE) and a greatest magnetic enhancement(~118%) among bulk materials, single agglomerations and NPs. Furthermore, we explore the utility of theoretical investigation by density functional theory(DFT)calculations for studying OER process on NiZnFeO_x surfaces without and with spin alignment, indicating monodispersed NiZnFeO_xNPs with totally spin alignment facilitates the OER process under the external magnetic field. It is found that the well-dispersion of NiZnFeO_x NPs would increase the electrical conductivity and the surface spin state, resulting in promoting their OER activities. This work provides a test for uncovering the essential roles of NPs assembly to a significant promotion of their magnet-assisted OER.

关键词： Single entity OER magnetic enhancement Electrocatalysis Well-dispersion

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维普期刊数据库

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Towards Understanding Paleosols in Southern Levantine Eolianites:Integration of Micromorphology,Environmental Magnetism and Mineralogy

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Journal of Mountain Science 2009年第2期6卷 113-124页

作者： Alexander Tsatskin Tatyana S.Gendler Friedrich Heller Igal Dekman Gitti L.Frey Laboratory of Geology Zinman Institute of Archaeology University of HaifaHaifa 31905 Israel United Institute of Physics of the Earth RAS Bolshaya Gruzinskaya 10Moscow 123810 Russia Institut für Geophysik ETH ZürichCH-8092 Zürich Switzerland Department of Materials Engineering Technion Haifa 32000 Israel

The paper addresses the controversial question of the role of clay-sized dust in the formation of paleosols in coastal eolianites, Israel. At the Habonim type section, the pedocomplex dated by archaeology and luminescence to 45-135 ka ago shows at least three paleosols, not separated by non-soil sediments. The oldest reddish paleosol （apparently related to MIS 5） is magnetically enhanced, leached from carbonates, with signs of bioturbation and strongly aged clay coatings. The reddening is due to very fine, -20 nm, poorly crystallized, superparamagnetic （SP） hematite, as determined by Mossbauer studies. In subsoil, lithorelics of eolianite are found. Over time, the soil surface aggraded due to accelerated fine dust accumulation alongside local slope wash. On younger materials formed magnetically depleted vertisols, dominated by smectite-type expandable paramagnetic clays. In thin sections, vertisols exhibit strong stipple-speckled and striated b-fabric due to shrink-swell processes, impregnative calcite nodules and Fe-Mn redistribution. The uppermost hydric vertisol shows the strongest expression of juxtaposed features of recurrent calcite and Fe precipitation. This paleosol developed on colluvial soil materials, as evidenced by mixing of clay coated and uncoated grains of quartz and calcite allochems. M6ssbauer spectra show high amounts of Fe（III） incorporated in the clay structure, low amounts of SP goethite and absence of SP hematite. Whilst magnetic susceptibility drops in vertisols to minimal values, increase. The latter along ferrimagnetie grain sizes with differences in the hierarchy of microfabric features is taken as indication for lithologic discontinuities which may have resulted from continuous, albeit variable and low-intensity, input of eolian clay from both remote Saharan and local sources, roughly dated to the earlier to middle part of the Last Glacial.

关键词： Coastal sand loess deposition microfabrie hierarchy magnetic enhancement paramagnetic phyllosilicates MSssbauer effect

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