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Ancient deep roots for mesozoic world-class gold deposits in the north China craton:An integrated genetic perspective

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Geoscience Frontiers 2020年第1期11卷 203-214页

作者： Cheng-Xue Yang m.Santosh School of Earth Sciences and Resources China University of Geosciences(Beijing)Beijing 100083China Department of Earth Sciences University of AdelaideAdelaideSA 5005Australia Key Lab of Submarine Geosciences and Prospecting Techniques Ministry of EducationCollege of Marine GeosciencesOcean University of ChinaQingdao 266100China Yonsei Frontier Lab Yonsei UniversitySeoul 03722Republic of Korea

The North China Craton(NCC)hosts some of the world-class gold deposits that formed more than 2 billion years after the major orogenic cycles and *** diverse models for the genesis of these deposits remain equivocal,and mostly focused on the craton margin examples,although synchronous deposits formed in the interior *** we adopt an integrated geological and geophysical perspective to evaluate the possible factors that contributed to the formation of the major gold deposits in the *** the Archean tectonic framework of the NCC,the locations of the major gold deposits fall within or adjacent to greenstone belts or the margins of *** the Paleoproterozoic framework,they are markedly aligned along two major collisional sutures-the Trans North China Orogen and the Jiao-Liao-Ji *** the mesozoic intrusions hosting these deposits do not carry adequate signals for the source of gold,we explore the deep roots based on available geophysical *** show that the gold deposits are preferentially distributed above zones of uplifted mOHO and shallow LAB corresponding to thinned crust and eroded sub-lithospheric mantle,and that the mineralization is located above regions of high heat flow representing mantle *** NCC was at the center of a multi-convergent regime during the mesozoic which intensely churned the mantle and significantly en riched *** geophysical data on moho and LAB upwarp from the centre towards east of the craton is more consistent with paleo-Pacific slab subduction from the east exerting the dominant control on lithospheric *** on these results,and together with an evaluation of the geochemical and isotopic features of the mesozoic magmatic intrusions hosting the gold mineralization,we propose a genetic model that invokes reworking of ancient Au archives preserved in the lower crust and metasomatised upper mantle and which were generated through multiple subduction,underplating and cumulation ev

关键词： Gold metallogeny Subduction tectonics Lithospheric thinning mantle metasomatism North China craton

Co-,Fe-,Ni-doped and co-doped rutile GeO_(2):insights from ab-initio calculations

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Communications in Theoretical Physics 2022年第4期74卷 113-126页

作者： R Essajai E Salmani m Bghour A Labrag F Goumrhar m Fahoume H Ez-Zahraouy materials and Subatomic Physics Laboratory Faculty of SciencesIbn Tofail UniversityKenitraMorocco Group of Semiconductors and Environmental Sensor Technologies-Energy Research Center Faculty of ScienceMohammed V UniversityB.P.1014RabatMorocco Laboratory of Condensed matter and Interdisciplinary Sciences Department of PhysicsFaculty of SciencesMohammed V UniversityP.O.Box 1014RabatMorocco Equipe des matériaux Supraconducteursàhaute température critique Department of PhysicsIbn Zohr UniversityFaculty of SciencesBP:8106AgadirMorocco Faculty of Applied Sciences Route Nationale N°10 citéAzrouAit MelloulIbn Zohr UniversityAit MelloulIbn Zohr UniversityMorocco Higher School of Education and Training of El Jadida(ESEF) Chouaib Doukkali UniversityEl Jadida 24000Morocco Laboratory of Physics of High Energy Modeling&Simulations(LPHE-MS)Faculty of SciencesMohammed V University of RabatIbn BatoutaB.P.1014 RabatMorocco Laboratoire des Sciences de l’Ingénieur pour l’Energie Ecole Nationale des Sciences Appliquées d’El Jadida(ENSA-J)BP 1166EL Jadida Plateau24002Morocco

Rutile germanium oxide(rutile GeO_(2)),a semiconductor,can act as a half-metallic compound and is a promising material for spintronic and optoelectronic *** were performed using the Korringa–Kohn–Rostoker(KKR)approach and the coherent potential approximation(CPA),which were further combined with two approximations,the local density approximation(LDA)and the self-interaction corrected LDA approximation(LDA-SIC),to study the electronic structure of bulk rutile GeO_(2) doped and co-doped with three transition-metal impurities:Fe,Co,and *** doping value was set to 10%,while the co-doping level was set to 5%for each *** main findings of this work are:(1)a direct ultrawide bandgap of4.80 ev is observed and the rutile GeO_(2) exhibits an N-type semiconducting property.(2)Doped and co-doped GeO_(2) acquire a magnetic behavior and exhibit half-metallicity.(3)The mechanism responsible for these properties is also studied.(4)The critical temperature can reach 334 K when GeO_(2) is doped with Fe,while it rises to 398 K when it is co-doped with Fe and Co.(5)The spin polarization can be improved by *** can be inferred that rutile GeO_(2) doped or codoped with(Co,Fe)transition metals can be considered to be potential candidates for spintronic and optoelectronic applications.

关键词： LDA approximation spintronic Curie temperature spin polarization LDA-SIC approximation rutile germanium oxide

Crystallization kinetics of Sn_(40)Se_(60) thin films for phase change memory applications

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Journal of Semiconductors 2015年第6期36卷 17-20页

作者： Joshua m.Kundu Patrick m.Karimi Walter K.Njoroge Department of Physics Kenyatta University

The crystallization kinetics of Sn4oSe6o thin films has been successfully investigated using sheet resis- tance versus temperature measurements. Thermal evaporation was used to deposit the films on ordinary glass sub- strates. The crystallization temperature for Sn4oSe60 thin film was found to be 156.6 -t- 0.3 ~C. In the as-deposited state, the sheet resistance was found to be 195 mf2/[2, this value declined to 1560 f2/[2] upon annealing. The value of activation energy obtained from the Kissinger plot was 0.62 ＋ 0.07 ev. From the results obtained, SnaoSe60 is a promising alloy for PCm application because of its high electrical contrast, high crystallization temperature, and relatively high activation energy.

关键词： crystallization temperature activation energy electrical contrast phase change memory

Optical properties and radiative rates of Nd^(3+) doped zinc-sodium phosphate glasses

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Journal of Rare Earths 2019年第3期37卷 253-259页

作者： A.A.El-maaref Shimaa Badr Kh.S.Shaaban E.A.Abdel Wahab m.m.ElOkr Physics Department Faculty of Science Al-Azhar University modern Academy for Engineering & Technology Chemistry Department Faculty of Science Al-Azhar University

Preparation using melt quenching technique and optical characterizations of Nd^(3+) doped Zn-Na phosphate glasses are presented. The structure of the present glasses was studied using X-ray diffraction and FT-IR spectroscopy. UV-vis spectra of the present glasses were analyzed at different concentrations of Nd_2 O_3. The effect of neodymium concentration on the density and energy band gap was investigated. The density of the present glasses slightly increases with the increasing of Nd_2 O_3. A small variation of energy band gap with the increasing of neodymium content is observed as well, while E_g values decrease with the increase of Nd_2 O_3 content. The E_g values lie between 4.36 and 4.69 ev. Based on the measured optical spectra, Judd-Ofelt theory was used to determine the optical parameters such as line strengths, optical intensity parameters(Ω_t), transition probabilities, and transition lifetimes. Hypersensitive transitions were identified in the absorption spectrum, the greatest line strengths are recorded at the transitions^2 G_(7/2)+ ~4 G_(5/2), ~4 S_(3/2) + ~4 F_(7/2) and ~4 D_(1/2) + ~4 D_(3/2)+ ~4 D_(5/2) + ~2 I_(11/2) with wavelengths of 580, 475 and 355 nm,respectively. Lifetimes of the important ~4 F_(3/2) laser-level were determined; which show decreasing trend with the increasing of Nd_2 O_3 content and are found to be between 0.838 and 1.595 ms. The uncertainty of the present results was estimated. The RmS deviations were determined, which show lower values than those in the literature.

关键词： Phosphate glass UV-vis spectroscopy Judd-Ofelt Radiative rates Rear earth ions

Photoluminescence characteristics of soft PZT 53/47 ceramic doped at A and/or B sites

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Journal of Advanced Ceramics 2018年第2期7卷 109-116页

作者： m.D.DURRUTHY-RODRíGUEZ J.J.GERVACIO-ARCINIEGA m.HERNáNDEZ-GARCíA J.m.YánEZ-LImóN Universidad Nacional evangélica Departamento de Física Aplicada Instituto de CibernéticaMatemáticay FísicaCITMA Catedrático CONACYT-Facultad de Ciencias Físico matemáticas Benemérita Universidad Autónoma de Puebla CINVESTAV-Unidad Querétaro del IPN Libramiento Norponiente 2000Fracc.Real de Juriquilla

This study presents the photoluminescence characteristics of the PZT 53/47 system doped at A and/or B sites, with Nb(PZTN), La(PLZT), and Nb–La(PLZTN) in the concentration range from 0.2 to 1.0 molar fraction. The intensity of the emission bands of the system PZTN is two orders higher than the intensity of the emission bands of the systems PLZT and PLZTN, and these emission bands are located at 1.73 ev(718 nm), 2.56 ev(485 nm), and 2.93 ev(424 nm). The origin of the luminescence in these systems is associated with lead and oxygen vacancies produced during the sintering process. The results from X-ray diffraction(XRD) show a mixture of rhombohedral and tetragonal phases. The system PZTN shows a higher tetragonal phase concentration, while PLZT and PLZTN systems show a higher rhombohedral phase concentration. The cell volume shows an increase with dopant concentration only in the case of the PLZTN system. The band gap energy shows a small variation in the PZTN and PLZTN cases around 3.0 ev, a close value to the band gap energy of the pure PZT 53/47 sample. The system PLZT shows an increasing behavior until 4.41 ev for the higher dopant concentration.

关键词： photoluminescence PZT ceramics band structure X-ray diffraction(XRD)

Canted antiferromagnetic and optical properties of nanostructures of mn_2O_3 prepared by hydrothermal synthesis

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Chinese Physics B 2012年第11期21卷 441-447页

作者： Qurat-ul-ain Javed Wang Feng-Ping m.Yasir Rafique Arbab mohammad toufiq m.Zubair Iqbal Department of Physics School of Mathematics and PhysicsUniversity of Science and Technology Beijing

We have reported new magnetic and optical properties of mn2O3 nanostructures. The nanostructures have been synthesized by the hydrothermal method combined with the adjustment of pH values in the reaction system. The particular characteristics of the nanostructures have been analyzed by employing X-Ray diffraction （XRD）, scanning electron microscopy （SEm）, energy dispersive X-ray （EDX） analysis, transmission electron microscopy （TEm）, high resolution transmission electron microscopy （HRTEm）, Raman spectroscopy （RS）, UV-visible spectroscopy, and the vibrating sample magnetometer （VSm）. Structural investigation manifests that the synthesized mn2O3 nanostructures are orthorhombic crystal. magnetic investigation indicates that the mn2O3 nanostructures are antiferromagnetic and the antiferromagnetic transition temperature is at TN = 83 K. Furthermore, the mn2O3 nanostructures possess canted antiferromagnetic order below the Neel temperature due to spin frustration, resulting in hysteresis with large coercivity （1580 Oe） and remnant magnetization （1.52 emu/g）. The UV-visible spectrophotometry was used to determine the transmittance behaviour of mn203 nanostructures. A direct optical band gap of 1.2 ev was acquired by using the Davis-mott model. The UV-visible spectrum indicates that the absorption is prominent in the visible region, and transparency is more than 80% in the UV region.

关键词： mn2O3 orthorhombic nanocrystals UV transparency canted antiferromagnetic property

Determination of interface states and their time constant for Au/SnO_2 /n-Si (mOS) capacitors using admittance measurements

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Chinese Physics B 2013年第4期22卷 429-433页

作者： H. m. Baran A. Tataroglu Department of Physics Faculty of Arts and Sciences Gazi University

The frequency dependence of admittance measurements （capacitance–voltage （C–V ） and conductance–voltage （G/ω–V ）） of Au/SnO2 /n-Si （mOS） capacitors was investigated by taking into account the effects of the interface states （N ss ） and series resistance （Rs ） at room temperature. Admittance measurements were carried out in frequency and bias voltage ranges of 1 kHz–1 mHz and （ 5V）–（＋9V）, respectively. The values of N ss and R s were determined by using a conductance method and estimating from the admittance measurements of the mOS capacitors. At low frequencies, the interface states can follow the AC signal and yield excess capacitance and conductance. In addition, the parallel conductance （G p /ω） versus log（f） curves at various voltages include a peak due to the presence of interface states. It is observed that the N ss and their time constant （τ） range from 1.23 ×10 12 ev-1 ·cm-2 to 1.47 ×10 12 ev-1 ·cm-2 and from 7.29 ×10-5 s to 1.81 ×10-5s, respectively.

关键词： mOS capacitor admittance measurements interface states

Analysis of electron energy distribution function in a magnetically filtered complex plasma

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Chinese Physics B 2013年第4期22卷 324-329页

作者： m K Deka H Bailung N C Adhikary Physical Sciences Division Institute of Advanced Study in Science and Technology Vigyan Path Paschim Boragaon Garchuk Guwahati-781035 Assam India

The electron energy distribution function （EEDF） for a magnetically filtered dusty plasma is studied in a dusty double plasma device where the electron energy can be varied from 0.15 ev to ～ 2.8 ev and plasma density from 10 6 cm-3 to 10 9cm-3 . The characteristics of EEDF for these ranges of plasma parameters are investigated in a pristine plasma as well as in a dusty plasma. The results show that in the presence of dust, there is a drastic modification in EEDF patterns in a plasma with higher electron temperature and density than those in a low temperature and low density plasma produced by the magnetic filter.

关键词： dusty plasma magnetic filter electron energy distribution function

Structural and photoluminescence properties of La3+ doped CdO nanophosphors synthesised via green mediated solution combustion route

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Journal of Rare Earths 2019年第9期37卷 916-923,I0001页

作者： m.S. Geetha H.N. Shivananjaiah Vijaya Composite College Bangalore560 003India Government Science College Nrupatunga RoadBangalore 560 001India

This paper reports a facile environmentally safe green combustion synthesis method of La3+doped CdO nanoparticles(NPs)using different concentrations of Aloe vera(A.V)gel as combustible *** crystallite size obtained using PXRD pattern is found to be 12-22 *** structural analysis was further analysed by Rietveld refinement *** X-ray photoelectron spectroscopy(XPS)analysis reveals the presence of two electronic states of CdO around 400 and 411 ev attributed to Cd 3 d3/2 and 3 d3/2,*** photoluminescence(PL)studies were carried upon 350 nm excitation *** PL emission spectra are found to have two prominent peaks centered at 410 and 510 nm and are attributed to 5D3→7F1 and 5D1→7F0 transitions,*** Commission International de l’Eclairage(CIE)chromaticity diagram reveals blue-green color *** correlation color temperature(CCT)value is found to be around^9793 *** obtained results suggest that the product is quite useful for cool light emitting diode applications when doping concentration is 2 mol%.

关键词： Green synthesis Nanostructures Photoluminescence Judd-ofelt Rare earths CdO