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Neutron capture effects and pre-atmospheric sizes of meteoroids

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Chinese Science Bulletin 2003年第20期48卷 2236-2240页

作者： WANG Daode & LIN Yangting Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China Correspondence should be addressed to Wang Daode (e-mail: gzwangdd @***) Guangzhou Institute of Geochemistry Chinese Academy of Sciences Guangzhou 510640 China

excesses of 80Kr and 82Kr, produced by secondary neutron capture effects of 79Br and 81Br, were observed in meteorites. epithermal neutron flux, Jn (30—300 ev), and fast neutron flux, Jn( > 5 Mev), were determined according to reactions of 79Br(n, gb)80Kr, 81Br(n, gb)82Kr, and 24Mg(n, a)21Ne, respectively. Cosmogenic noble gases of several ordinary chondrites fell in China indicate a positive relationship between Jn (30—300 ev)/Jn ( > 5 Mev) ratio and Jn (30—300 ev). This suggests large pre-atmospheric sizes of the meteorites, and a considerable fraction of the secondary neutrons were slowed down to epithermal energy. According to its relationship with Jn (30—300 ev)/Jn ( > 5 Mev) ratio, the pre-atmospheric minimum radii and masses of several Chinese chondrites were estimated as below: Zhaodong: 60 cm, 3200 kg; Laochengzhen: 23 cm, 490 kg; Suizhou: 31 cm, 450 kg; Xi Ujimgin: 22 cm, 160 kg; Dongtai: 21 cm, 140 kg.

关键词：流星体陨星中子俘获大气层前尺寸宇宙成因核素

Synthesis and Some Properties of Metal Organic Chemical Vapour Deposited Molybdenum Oxysulphide Thin Films

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Journal of Materials Science & Technology 2010年第6期26卷 552-557页

作者： B.Olofinjana G.O.egharevba M.A.eleruja C.Jeynes A.V.Adedeji O.O.Akinwunmi B.A.Taleatu C.U.Mordi e.O.B.Ajayi Department of Physics Obafemi Awolowo UniversityIle-IfeNigeria Department of Chemistry Obafemi Awolowo UniversityIle-IfeNigeria Department of electronic and electrical engineering University of SurreyGuildfordSurrey GU2 5XHUK Department of Chemistry and Physics Elizabeth City State UniversityElizabeth CityNC 27909USA

Molybdenum oxodithiocarbamate was prepared as thin films which were deposited on sodalime glass a single solid source precursor for molybdenum oxysulphide substrates using metal organic chemical vapour deposition （MOCVD） technique at a temperature of 420~C. Rutherford backscattering spectroscopy （RBS） was used to determine the elemental composition of the film which showed that the films contained large amounts of oxygen. The large amount of oxygen was attributed to the large abundance of oxygen in the starting material. A direct optical energy gap of 3.31 ev was obtained from the analysis of the absorption spectrum. The scanning electron microscopy （SeM） micrographs of the films showed that the films were continuous and porous. An estimated average size of the grains was below 5 #m. X-ray diffraction （XRD） showed that the deposited films were crystalline in nature.

关键词： Molybdenum oxodithiocarbamate Molybdenum oxysulphide Metal organic chemical vapour deposition (MOCVD) Thin film

采用稀释成盐法从富硼浓缩盐卤中合成的镁硼酸盐化合物及其结构与性质（英文）

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无机化学学报 2016年第2期32卷 305-312页

作者：彭姣玉林锋杨波王立平 Dinnebier e.Robertc 董亚萍李武中国科学院青海盐湖研究所西宁810008 中国科学院大学北京100049 中国科学院盐湖资源综合高效利用重点实验室西宁810008 德国马克斯-普朗克固体研究所斯图加特70569

通过稀释成盐法在富硼浓缩盐卤体系Na-K-Mg-Cl-SO_4中合成了一种新的六硼酸镁Mg[B_6O_7(OH)_6]·5H_2O化合物。根据X射线粉末衍射数据对其晶体结构进行了精修,并采用红外及拉曼光谱法对其结构进行了表征,分析了其光谱及结构特征。结果表... 详细信息

通过稀释成盐法在富硼浓缩盐卤体系Na-K-Mg-Cl-SO_4中合成了一种新的六硼酸镁Mg[B_6O_7(OH)_6]·5H_2O化合物。根据X射线粉末衍射数据对其晶体结构进行了精修,并采用红外及拉曼光谱法对其结构进行了表征,分析了其光谱及结构特征。结果表明,该化合物由1个Mg原子、1个B_6O_7(OH)_6基团和5个H_2O分子构成,Mg原子以六配位形式与氧结合形成畸变MgO_6八面体构型;热重分析表明,高温分解过程该化合物脱水转化为四硼酸镁MgB_4O_7;通过紫外可见漫反射法求得其禁带宽度为4.44 ev。

关键词：镁硼酸盐含硼盐卤稀释成盐法结构热稳定性

Bandgap energy determination of In As Sb epilayers grown by molecular beam epitaxy on Ga As substrates

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Progress in Natural Science:Materials International 2019年第4期29卷 472-476页

作者： K.Murawski e.Gomó?ka M.Kopytko K.Grodecki K.Michalczewski ?.Kubiszyn W.Gawron P.Martyniuk A.Rogalski J.Piotrowski Institute of Applied Physics Military University of Technology Vigo System S.A.

InAsSb ternary alloys can be considered as an alternative to HgCdTe for mid-wavelength,as well as long-wavelength infrared *** energy bandgap exhibits nonlinearity versus Sb composition,and hence the correct determination of its value is necessary for the effective design and simulation of optoelectronic *** commonly used expression on the InAsSb energy bandgap provided by Wieder and Clawson overestimated energy bandgap values at high *** this paper,we present two modified empirical relationships which are based on the experimental data obtained in our laboratory and published *** are correct for a wide range of Sb molar composition and *** nonlinearity of the energy gap is described with the adequate bowing *** data collected in our experiment,for samples grown on lattice mismatched GaAs substrates,fits well with a bowing factor of C=0.72 *** minimum bandgap energy that can be reached at room temperature is about 73 mev for a Sb mole fraction,x=*** comparison,the bandgap at low temperatures collected in the literature for samples grown on lattice-matched GaSb substrates is smaller than the measured values in our experiment and fits well with a parabola with C=0.9 ev.

关键词： InAsSb Bandgap energy Bowing Ⅲ-Ⅴ ternary alloys Infrared detectors

Metal Organic Chemical Vapour Deposited Thin Films of Cobalt Oxide Prepared via Cobalt Acetylacetonate

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Journal of Materials Science & Technology 2009年第1期25卷 85-89页

作者： C.U. Mordi M.A. eleruja B.A. Taleatu G.O. egharevba A.V. Adedeji O.O. Akinwunmi B. Olofinjana C. Jeynes e.O.B. Ajayi Department of Physics Obafemi Awolowo University Ile-Ife Nigeria Department of Chemistry Obafemi Awolowo University Ile-Ife Nigeria Department of Physics Auburn University Alabama United States Department of electronics and electrical engineering University of Surrey Guildford Surrey GU2 7XH UK

The single solid source precursor, cobalt （Ⅱ） acetylacetonate was prepared and characterized by infrared spectroscopy. Thin films of cobalt oxide were deposited on soda lime glass substrates through the pyrolysis （metal organic chemical vapour deposition （MOCVD）） of single solid source precursor, cobalt acetylacetonate, Co[C5H7O2]2 at a temperature of 420℃. The compositional characterization carried out by rutherford backscattering spectroscopy and X-ray diffraction （XRD）, showed that the films have a stoichiometry of Co2O3 and an average thickness of 227±0.2 nm. A direct energy gap of 2,15±0.01 ev was calculated by the data obtained by optical absorption spectroscopy. The morphology of the films obtained by scanning electron microscopy, showed that the grains were continuous and uniformly distributed at various magnifications, while the average grain size was less than i micron for the deposited thin films of cobalt oxide.

关键词： Precursor Thin film Oxide Metal organic chemical vapour deposition (MOCVD) Rutherford backscattering spectroscopy (RBS)

Thermodynamic criterion for searching high mobility two-dimensional electron gas at KTaO_(3)interface

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Chinese Physics B 2021年第7期30卷 70-73页

作者： Wen-Xiao Shi Hui Zhang Shao-Jin Qi Jin-e Zhang Hai-Lin Huang Bao-Gen Shen Yuan-Sha Chen Ji-Rong Sun Beijing National Laboratory for Condensed Matter Physics and Institute of Physics Chinese Academy of SciencesBeijing 100190China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100049China Fujian Innovation Academy Chinese Academy of SciencesFuzhou 350108China Songshan Lake Materials Laboratory Dongguan 523808China Spintronics Institute University of JinanJinan 250022China

Two-dimensional electron gases(2 DeGs)formed at the interface between two oxide insulators present a promising platform for the exploration of emergent *** most of the previous works focused on SrTiO_(3-)based 2 DeGs,here we took the amorphous-ABO_(3)/KTaO_(3)system as the research object to study the relationship between the interface conductivity and the redox property of B-site metal in the amorphous *** criterion of oxide-oxide interface redox reactions for the B-site metals,Zr,Al,Ti,Ta,and Nb in conductive interfaces was revealed:the formation heat of metal oxide,ⅢH_(f)^(o),is lower than-350 kJ/(mol O)and the work function of the metalΦis in the range of 3.75 eve found that the smaller absolute value ofⅢH_(f)^(o)and the larger value ofΦof the B-site metal would result in higher mobility of the two-dimensional electron gas that formed at the corresponding amorphous-ABO_(3)/KTaO_(3)*** finding paves the way for the design of high-mobility all-oxide electronic devices.

关键词： two-dimensional electron gas oxygen vacancies thermodynamic criterion Hall mobility

electron Momentum Spectroscopy of Metal and Metal Oxide Thin Films

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Electron Momentum Spectroscopy of Metal and Metal Oxide Thin...

Vertically aligned Ni/NiO nanocomposites with abundant oxygen deficient hetero-interfaces for enhanced overall water splitting

1996年中国青年学者物理学讨论会

作者： M.Vos S.Canney A.S.Kheifets I.e.McCarthy e.Weigold electronic Structure of Materials Centre The Flinders University of South Australia AdelaideSA 5001Australia Research School of Physical Sciences and engineering The Australian National University CanberraACT 2000Australia

electron momentum spectroscopy(eMS),a new spectroscopic technique,measures electron momentum distributions directly and visualizes the dispersion relation between energy and momentum of electrons in *** present eMS measurements of two kinds of thin films:a free electron metal:Al,and an ionic insulator:*** Al,the measured spectral momentum density plot shows a parabolic dispersion pattern characterizing a free electron metal and the agreement with a linear muffin-tin orbital (LMTO)calculation of spherically averaged Al is *** the spectral momentum density plot of AlO,the measurement shows clearly two major features and they are related to the upper valence band and the lower valence band of *** features are qualitatively reproduced by the LMTO calculation on a spherically averaged α-*** effects on core level shift are also studied by measuring binding energy spectra of the Al 2p level for clean Al,partly oxidized Al and AlO.A 3-ev energy shift of the Al 2p peak is observed.

关键词：

来源： cnki会议评论

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Science China Chemistry 2022年第10期65卷 1885-1894页

作者： Hongxia Wang Meiyan Cui Gaoliang Fu Jiaye Zhang Xingyu Ding Irene Azaceta Matthew Bugnet Demie M.Kepaptsoglou Vlado K.Lazarov Victor Ade la Peña O’Shea Freddy e.Oropeza Kelvin H.L.Zhang State Key Laboratory of Physical Chemistry of Solid Surfaces College of Chemistry and Chemical EngineeringXiamen UniversityXiamen 361005China State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhou 350002China Henan Provincial Key Laboratory of Nanocomposites and Applications Institute of Nanostructured Functional MaterialsHuanghe Science and Technology CollegeZhengzhou 450006China Department of Physics University of YorkHeslingtonYorkYO105DDUK SuperSTeM Laboratory SciTech Daresbury CampusDaresbury WA44ADUK School of Chemical and Process engineering Univeristy of LeedsLeeds LS29JTUK Univ Lyon CNRSINSA LyonUCBLMATEISUMR 551069621 VilleurbanneFrance Photoactivated Processes Unit IMDEA Energy InstituteParque Tecnológico de MóstolesAvda.Ramón de la Sagra 328935 MóstolesMadridSpain

The design of heterostructured transition metal-based electrocatalysts with controlled composition and interfaces is key to increasing the efficiency of the water electrolysis and the elucidation of reaction *** this work,we report the synthesis of well-controlled vertically aligned Ni/NiO nanocomposites consisting of Ni nanoclusters embedded in NiO,which result in highly efficient electrocatalysts for overall water *** show that such a high catalytic efficiency toward both the hydrogen evolution reaction(HeR)and the oxygen evolution reaction(OeR)originates from a synergetic effect at Ni/NiO interfaces that significantly reduces the energy barrier for water dissociation,and favours the formation of reactive H*intermediates on the Ni side of the interface,and OH_(ads) on the NiO side of the interface.A study of water chemisorption based on near-ambient pressure photoelectron spectroscopy indicates that the abundant hetero-interfaces in Ni/NiO nanocomposite promote the dissociation of water with a three-fold increase in the surface concentration of OH_(ads) compared with pure *** functional theory calculations indicate that Ni/NiO interface leads to the reduction of the water dissociation energy barrier due to a high concentration of oxygen vacancies at NiO side of the interface,whereas the formation of highly active metallic Ni sites with an optimal value of Gibbs free energy of H*(ΔG_(H*)=−0.16 ev)owes to a favourable adjustment of the electron energetics at the interface,thus accelerating the overall electrochemical water splitting.

关键词： water splitting hydrogen evolution reaction electronic structure heterostructure vertically aligned nanocomposites

electron Momentum Spectroscopy of Metal and Metal Oxide Thin Films

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电子显微学报 1997年第4期 177-180页

作者： X.Guo\ M. Vos \ S. Canney \ A.S.Kheifets \ I.e. McCarthy\ e.Weigold * (electronic Structure of Materials Centre, The Flinders University of South Australia, Adelaide, SA 5001, Australia) ( * Research School of Physical Sciences and engineering

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关键词： Thin Oxide and Metal Momentum electron Films