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Structural Controls and Predictive Mapping of Tin, niobium and Tantalum Mineralization Associated with the Mayo Darlé Stanniferous Granitoids;Contributions of Geostatistics

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Journal of Geoscience and Environment Protection 2024年第1期12卷 180-210页

作者： Bah-Yero Liman Ngounouno Ismaïla Mbowou Gbambié Isaac Bertrand Alpha Baster Kenfack Fokem André William Boroh Amadou Diguim Kepnamou Department of Earth Sciences Faculty of Science University of Ngaoundéré Ngaoundéré Cameroon Department of Mining Geology School of Geology and Mining and Engineering University of Ngaoundéré Meiganga Cameroon Department of Earth Sciences Faculty of Science University of Garoua Garoua Cameroon

The aim of this study of the spatial dispersion of tin, niobium and tantalum mineralization associated with the Mayo Darlé granitoids was to produce prospecting guides through predictive maps of Sn, Nb and Ta in the region. It was based on a database (in appendix) obtained after analysis of rock samples (greisens and quartz veins) collected in the field, using a portable X-ray fluorescence (XRF) spectrometer. Two approaches were used: 1) structural studies in the field using the directions of veins and fractures 2) the use of variographic maps, an essential element in geostatistics for determining directional anisotropies. A joint synthesis of the modelling results shows that tin, tantalum and niobium mineralization at Mayo Darlé is concentrated along strike intervals N315E to N320E, with mineralization also occurring along strike N35E for high-grade Sn, medium-grade Ta and low-grade Nb. In short, mineral concentrations disperse progressively in space: positively from east to west for tantalum and niobium, and inversely for tin.

关键词： Mayo Darlé Tin niobium Tantalum Geostatistics Mapping

The influence of adding niobium and vanadium on hydrogen diffusion in 22MnB5 hot stamping steel

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Journal of Iron and Steel Research(International) 2023年第10期30卷 2031-2042页

作者： Peng-wei Zhou Zhi-yi Yan Ke Wang Tao Liu Si-jia Chen Zhen Ma Ju-sha Ma Wei Ding Yi Luo Bing-gang Liu Wei Li Shanghai Institute of Space Power-Sources Shanghai 200245China State Key Lab of Metal Matrix Composites School of Materials Science and EngineeringShanghai Jiao Tong UniversityShanghai 200245China

Adding alloying elements is always considered as an effective method to enhance the resistance against hydrogen embrittlement in steels.Nb and V were added into 22MnB5 hot stamping steel,and then their influences on hydrogen permeation of 22MnB5 steel suffering from corrosion in 3.5%NaCl aqueous solution were investigated.The results showed that the addition of Nb/V could reduce the hydrogen permeation content due to solution corrosion.Electrochemical techniques including electrochemical impedance spectroscopy and overpotential stepping hydrogen permeation test con-firmed that compared to the original 22MnB5 steel,22MnB5-NbN steel owned a higher corrosion resistance and a higher hydrogen diffusion resistance.Furthermore,it was confirmed that Nb-V-alloyed 22MnB5 steel showed higher resistance against hydrogen embrittlement than the Nb-V-free counterpart,which should be related to the presentence of nanoscaled Nb/V-containing precipitates as the irreversible trapping sites for hydrogen detected by thermal desorption spectroscopy.Finally,the lattice diffusion coefficient of hydrogen DL was determined in steels with and without Nb and V.

关键词： Hydrogen permeation Corrosion Hot stamping steel niobium Vanadium Thermal desorption spectroscopy

Review on niobium application in microalloyed steel

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Journal of Iron and Steel Research(International) 2022年第10期29卷 1513-1525页

作者： Lu-yan Sun Xiang Liu Xi Xu Shu-wei Lei Hui-gai Li Qi-jie Zhai State Key Laboratory of Advanced Special Steel and Shanghai Key Laboratory of Advanced Ferrometallurgy and School of Materials Science and Engineering Shanghai UniversityShanghai200444China Center for Advanced Solidification Technology(CAST) School of Materials Science and EngineeringShanghai UniversityShanghai200444China Ansteel Group Iron and Steel Research Institute AnsteelAnshan114001LiaoningChina

With the rapid development of high-strength low-alloy(HSLA)steel,Nb as an important microalloying element has received more and more attention in recent years.The application and behavior of Nb in HSLA steel,including microstructures optimization,refining grain size,and precipitation behavior of Nb-containing phases,were reviewed.Nb could play an important role in following manners:(1)Nb-containing phases promote ferrite formation,and Nb solute promotes bainite formation.(2)Nb solute atoms and Nb-containing phases can inhibit the growth of austenite grains and austenite recrystallization.(3)Nb(C,N)that precipitates in ferrite/bainite can provide more significant strengthening contribution(more than 300 MPa)than that in austenite(about 100 MPa).Some reasonable suggestions for the production of Nb-bearing HSLA steel with excellent mechanical properties were put forward.

关键词： niobium Precipitate Microalloying High-strength low-alloy steel

niobium doping induced mirror twin boundaries in MBE grown WSe2 monolayers

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Nano Research 2020年第7期13卷 1889-1896页

作者： Bo Wang Yipu Xia Junqiu Zhang Hannu-Pekka Komsa Maohai Xie Yong Peng Chuanhong Jin Key Laboratory for Magnetism and Magnetic Materials of Ministry of Education School of Physical Science and TechnologyLanzhou UniversityLanzhou 730000China State Key Laboratory of Silicon Materials School of Materials Science and EngineeringZhejiang UniversityHangzhou 310024China Physics Department The University of Hong KongPokfulam RoadHong Kong 999077China Department of Applied Physics Aalto University00076 AaltoFinland Hunan Institute of Advanced Sensing and Information Technology Xiangtan UniversityXiangtan 411201China

Mirror twin boundary(MTB)brings unique one-dimensional(1D)physics and properties into two-dimensional(2D)transition metal dichalcogenides(TMDCs),but they were rarely observed in non-Mo-based TMDCs.Herein,by post growth Nb doping,high density 4|4E-W and 4|4P-Se mirror twin boundaries(MTBs)were introduced into molecular beam epitaxy(MBE)grown WSe2 monolayers.Of them,4|4E-W MTB with a novel structure was discovered experimentally for the first time,while 4|4P-Se MTBs present a random permutations of W and Nb,forming a 1D alloy system.Comparison between the doped and non-doped WSe2 confirmed that Nb dopants are essential for MTB formation.Furthermore,quantitative statistics reveal the areal density of MTBs is directly proportional to the concentration of Nb dopants.To unravel the injection pathway of Nb dopants,first-principles calculations about a set of formation energies for excess Nb atoms with different configurations were conducted,based on which a model explaining the origin of MTBs introduced by excess metal was built.We conclude that the formation of MTBs is mainly driven by the collective evolution of excess Nb atoms introduced into the lttice of host WSe2 crystal and subsequent displacement of metal atoms(W or Nb).This study provides a novel way to tailor the MTBs in 2D TMDC materials via proper metal doping and presents new opportunities for exploring the intriguing properties.

关键词： mirror twin boundaries niobium doping molecular beam epitaxy transition metal dichalcogenides niobium tungsten diselenide

niobium–tantalum oxide minerals in alluvial placer deposits from the Ngoura area,East-Cameroon

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Acta Geochimica 2021年第1期40卷 13-24页

作者： Francois Ndong Bidzang Elise Sababa Tessontsap Teutsong Ore Processing Laboratory Institute of Geological and Mining ResearchP.O.Box 4110YaoundeCameroon Department of Earth Sciences University of Yaounde 1.P.O.Box 812YaoundeCameroon

This work presents a preliminary mineralogical characterization of Nb-Ta oxide minerals from alluvial placers located in the Ngoura area,eastern Cameroon.The heavy minerals are characteristic of short hydromechanical transport and highlight the stability of Nb-Ta oxides during the weathering and transport.Nb-Ta mineralization in placer deposits from the Ngoura area may derive from local sedimentation.The assemblage of Nb-Ta oxides in the studied placers consists of tapiolite-(Fe)and tantalite-(Mn).Tapiolite-(Fe)exhibits high concentrations in Ta2O5(78.07-80.46 wt%)and FeO(12.18-13.66 wt%)and plots within a narrow range of Ta*(0.900-0.933)and Mn*(0.037-0.119),which correspond to the ranges typically observed in tapiolite-(Fe)worldwide.Tantalite-(Mn)shows Ta2O5 contents ranging from 62.17 to 69.45 wt%,Nb2O5 from 12.09 to 17.37 wt%,MnO from 7.63 to 12.49 wt%and FeO from 1.48 to 6.62 wt%.It is also characterized by a wider range of Mn*(0.538-0.891)and relatively homogeneous Ta/(Ta+Nb)(0.683-0.779)ratios.Texturally,the studied Nb-Ta minerals exhibit oscillatory zoning characterized by bright Ta-rich zones alternating with dark Nb-rich zones.This oscillatory zoning is progressive in some minerals and the alternating bands may appear regular to wavy with gradual transitions.Oscillatory zoning in Nb-Ta oxides from the Ngoura placers is considered to be a primary magmatic feature and is tentatively explained as a result of magmas mixing,rapid cooling or degassing/decompression of the igneous system.The geomorphology and the tropical humid climate of the eastern region offer suitable conditions for the deposition of alluvial placers.Therefore,niobium-tantalum minerals from the Ngoura placers must have been sourced from the weathering and erosion of alkaline granites and pegmatites widespread in the study area.

关键词： niobium Tantalum Tapiolite-(Fe) Tantalite-(Mn) Ngoura placer East Cameroon

Super-enrichment of lithium and niobium in the upper Permian Heshan Formation in Pingguo,Guangxi,China

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Science China Earth Sciences 2021年第5期64卷 753-772页

作者： Kunyue LING Hanjie WEN Qizuan ZHANG Chongguang LUO Hannian GU Shengjiang DU Wenxiu YU State Key Laboratory of Ore Deposit Geochemistry Institute of GeochemistryChinese Academy of SciencesGuiyang 550081China College of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijing 100049China College of Earth Science and Resources Chang’an UniversityXi'an 710054China Guangxi Bureau of Geology&Mineral Prospecting&Exploitation Nanning 530023China State Key Laboratory of Nuclear Resources and Environment East China University of TechnologyNanchang 330013China Faculty of Land Resource Engineering Kunming University of Science and TechnologyKunming 650093China

The upper Permian Heshan Formation in Pingguo,Guangxi,China,is strongly enriched in lithium(Li)and niobium(Nb).The lower bauxite layer contains 0.02–0.04 wt.%Nb_(2)O_(5)(averaging 0.035 wt.%),and the overlying clay rock layer contains 0.06–1.05 wt.%Li_(2)O(averaging 0.44 wt.%),both of which exceed the cut-off grades for independent Li and Nb deposits and are therefore highly prospective.In this study,a preliminary discussion of the genesis of the Li and Nb enrichment is presented to serve as a reference for the investigation,evaluation,and prospecting for clay-and sedimentary-type Li and Nb ores in other regions.The preliminary conclusions are that:(1)The bauxite ore contains abundant anatase,which positively correlates with the whole-rock concentrations of TiO_(2) and Nb,indicating that the Nb is hosted mainly in the anatase;(2)the cookeite content in the clay rock positively correlates with the whole-rock Li concentration,indicating that cookeite is the main carrier mineral of Li,and its genesis can be attributed to reactions between clay minerals(e.g.,pyrophyllite and illite)and Li-Mg-rich underground brine or pore water and groundwater in coastal areas;and(3)provenance analysis of immobile elements(Al,Ti,Nb,Ta,Zr,Hf,and rare earth elements)suggests distinct sources for the Nb-rich bauxite and the overlying Li-rich clay rocks,with the bauxite and Nb originating largely from alkaline felsic rocks in the Emeishan Large Igneous Province,and the clay rocks being derived from peraluminous or moderately fractionated felsic rocks associated with Permian Paleo-Tethyan magmatic arcs.

关键词： Heshan Formation Critical metal Lithium niobium Super-enrichment

Efficient polysulfide blocker from conductive niobium nitride@graphene for Li-S batteries

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Journal of Energy Chemistry 2020年第6期29卷 135-141,I0006页

作者： Huifa Shi Zhenhua Sun Wei Lv Shujie Xiao Huicong Yang Ying Shi Ke Chen Shaogang Wang Bingsen Zhang Quan-Hong Yang Feng Li Shenzhen Geim Graphene Center Tsinghua Shenzhen International Graduate SchoolTsinghua UniversityShenzhen 518055GuangdongChina Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016LiaoningChina Laboratory of Advanced Materials School of Materials Science and EngineeringTsinghua UniversityBeijing 100084China Nanoyang Group State Key Laboratory of Chemical EngineeringSchool of Chemical Engineering and TechnologyTianjin UniversityTianjin 300072China

Lithium sulfur batteries are one of the most promising alternative electrochemical systems,but their practical applications are largely hindered by the serious shuttling problems and sluggish redox kinetics.Here,the conductive and polar niobium nitride(NbN)is in-situ introduced onto graphene with ultrasmall size and high dispersion,and their composite is used to construct an efficient lithium polysulfide blocking layer.The graphene helps to construct highly conductive pathways,and niobium nitride serves as the sulfiphilic sites to chemically adsorb the migrating lithium polysulfides and catalyze their redox conversion.Hence,the cells with the Nb N/G interlayers exhibit a long cycle life with a lower capacity decay of 0.096%/cycle at 1 C for 300 cycles and high rate capability of 937 m Ah g^-1 at 2 C.Further coupling with a sulfur/carbon nanofiber electrode,the cell with an ultra-high sulfur loading of 10.8 mg cm^-2 delivers an areal capacity of 12.5 m Ah cm^-2 at 0.1 C.

关键词： Lithium-sulfur batteries niobium nitride Chemical adsorption Catalytic effect High loading

Unusual softening behavior of yield strength in niobium at high pressures

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Chinese Physics B 2018年第10期27卷 501-507页

作者：敬秋民何强张毅李守瑞柳雷侯琪玥耿华运毕延俞宇颖吴强 National Key Laboratory of Shock Wave and Detonation Physics Institute of Fluid PhysicsChina Academy of Engineering Physics

In situ synchrotron angle-dispersive x-ray diffraction experiments on niobium powders have been conducted at pressures up to 61 GPa and room temperature using the diamond anvil cell technique. From the full width at half maximum of the measured diffraction lines, the yield strength was derived with the line-width analysis theory. The niobium powder sample was found to be compressed more packed firstly and then yielded at~14 GPa–18 GPa. Following an initial increase in the yield strength with pressure, an obvious decrease was observed occurring at ~42 GPa–47 GPa accompanying with a typical pressure dependence above 47 GPa. The experimentally observed anomalous softening of the yield strength in niobium surprisingly follows the trend of the predicted unusual softening in the shear modulus by the recent theoretical investigations. The possible mechanisms, applicable to interpret the yield strength softening of materials at high pressure,were also discussed in detail.

关键词： x-ray diffraction niobium diamond anvil cell yield strength anomalous softening

Extraction of niobium, yttrium, and cerium from a low-grade niobium-bearing ore by roasting(NH_4)_2SO_4-Na_2SO_4-H_2SO_4 system

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Rare Metals 2014年第6期33卷 754-760页

作者： Wen-Cheng Gao Jian-Kang Wen Biao Wu He Shang National Engineering Laboratory of Biohydrometallurgy General Research Institute for Nonferrous Metals

A novel process of extracting niobium, yttrium,and cerium from a low-grade niobium-bearing ore by the roasting（NH4）2SO4-Na2SO4-H2SO4 system was experimentally studied. The influences of various factors,such as roasting temperature, roasting time, mass ratio of agents-to-ore and particle size fraction on the extraction of valuable metals were comprehensively investigated. It is found that the roasting Na2SO4-H2SO4 system is effective to extract the niobium, yttrium, and cerium. The obtained optimum conditions for the extraction of Nb, Y, and Ce are roasting temperature of 300 °C, roasting time of 3 h, mass ratio of Na2SO4：H2SO4：Ore of 0.5：1.0：1.0, and particle size fraction of-74 lm（~95 %）. Under the optimum condition, the maximum recovery of Nb, Y, and Ce can reach90.53 %, 92.15 %, and 98.04 %, respectively. All the results generated from this study will provide the fundamentals for Nb, Y, and Ce extraction from a niobiumbearing ore with low-grade.

关键词： Extraction niobium Yttrium Cerium Lowgrade