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Influence of Te doping on the dielectric and optical properties of InBi crystals grown by directional freezing

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International journal of Minerals,Metallurgy and Materials 2014年第5期21卷 503-509页

作者： c.j. Ajayakumar A.G. Kunjomana crystal Research centre Department of PhysicsChrist University

Stoichiometric pure and tellurium （Te） doped indium bismuthide （InBi） were grown using the directional freezing technique in a fabricated furnace. The X-ray diffraction profiles identified the crystallinity and phase composition. The surface topographical features were observed by scanning electron microscopy and atomic force microscopy. The energy dispersive analysis by X-rays was performed to identify the atomic proportion of elements. Studies on the temperature dependence of dielectric constant （e）, loss tangent （tan6）, and Ac conductivity （cry） reveal the existence of a ferroelectric phase transition in the doped material at 403 K. When InBi is doped with tellurium （4.04 at%）, a band gap of 0.20 eV can be achieved, and this is confirmed using Fourier transform infrared studies. The results thus show the conversion of semimetallic InBi to a semiconductor with the optical properties suitable for use in infrared detectors.

关键词： crystals indium bismuthide tellurium doping optical properties dielectric properties phase transitions

Hot cracking in AZ31 and AZ61 Magnesium Alloy

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journal of Materials Science & Technology 2011年第7期27卷 633-640页

作者： c.j. Huang c.M. cheng c.P. chou F.H. chen Department of Mechanical Engineering National Chiao Tung University Hsinchu 300 Taiwan China Department of Industrial Education National Taiwan Normal University Taipei 106 Taiwan China

This paper examined the impact of the number of thermal cycles and augmented strain on hot cracking in AZ31 and AZ61 magnesium alloy. Statistical analyses were performed. Following observation using a scanning electron microscope （SEM）, an energy dispersive spectrometer （EDS） was used for component analysis. Results showed that Al content in magnesium alloy has an effect on hot cracking susceptibility. In addition, the nonequilibrium solidification process produced segregation in Al content, causing higher liquid Mg-alloy rich Al content at grain boundaries, and resulting into liquefied grain boundaries of partially melted zone （PMZ）. In summary, under multiple thermal cycles AZ61 produced serious liquation cracking. AZ61 has higher （6 wt%） Al content and produced much liquefied Mg17Al12 at grain boundaries under multiple thermal cycles. The liquefied Mg17Al12 were pulled apart and hot cracks formed at weld metal HAZ due to the augmented strain. Since AZ31 had half the Al content of AZ61, its hot-cracking susceptibility was lower than AZ61. In addition, AZ61 showed longer total crack length （TcL） in one thermal cycle compared to that in three thermal cycles. This phenomenon was possibly due to high-temperature gasification of Al during the welding process, which resulted in lower overall Al content. consequently, shorter hot cracks exhibited in three thermal cycles. It was found the Al content of AZ31 and AZ61 can be used to assess the hot-cracking susceptibility.

关键词： Varestraint test Thermal cycles Hot-cracking susceptibility Gas tungsten arc welding (GTAW) AZ31 AZ61

Status and prospects for symmetric organic redox flow batteries

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journal of Energy chemistry 2025年第1期100卷 125-143页

作者： Md Al Raihan c.Adam Dyker Department of chemistry University of New Brunswick

As environmental concerns from fossil fuel consumption intensify, large-scale energy storage becomes imperative for the integration of renewable sources like wind, hydro, and solar with the electrical *** flow batteries, particularly those employing organic molecules, are positioned as a key technology for this purpose. This review explores the growing field of symmetric organic redox flow batteries(ORFBs) within this context. Unlike traditional asymmetric designs based on unique active materials for each electrode, symmetric ORFBs involve a single bipolar species for both electrodes. This review highlights the benefits of a symmetric design, and categorizes five distinct classes of organic bipolar molecules used in both aqueous and non-aqueous solvents. By providing a comprehensive overview of their cell cycling and performance characteristics, the strengths and weaknesses of the diverse categories of bipolar molecules are highlighted for both solvent systems, as are opportunities for future development. This should guide new research directions and advance the development of practical symmetric ORFBs.

关键词： Redox flow battery Symmetric battery Organic battery Aqueous electrolyte Non-aqueous electrolyte

Understanding and managing the morphology of branches incising into sand-clay deposits in the Dutch Rhine Delta

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International journal of Sediment Research 2013年第2期28卷 127-138页

作者： Kees SLOFF(c.j.) Ary VAN SPIjK Esther STOUTHAMER Arjan SIEBEN Deltares and Delft University of Technology PO Box 1772600MH Delftthe Netherlands Assis.Prof. Water management Rijkswaterstaat Zuid HollandPO Box 5563000 AN Rotterdamthe Netherlands Senior Advisor Utrecht University Faculty of GeosciencesPO Box 801153508 TCUtrechtthe Netherlands AssisProf. Water management Rijkswaterstaat Center for Water ManagementPO Box 178200 AA Lelystadthe Netherlands Senior Advisor

In the Rhine-Meuse delta in the south-western part of the Netherlands,the morphology of the river branches is highly dependent on the erodibility of the *** processes that were initiated after closure of the Haringvliet estuary branch by a dam(in 1970),caused a strong incision of several connecting *** to the geological evolution of this area the lithology of the subsoil shows large variations in highly erodible sand and poorly erodible peat and clay *** study shows how the geological information can be used to create 3D maps of the erodibility of the sub-soil, and how this information can be used to schematize the sub-soil in computational models for morphological *** incisement of sand patches between areas with poorly erodible bed causes deep scour holes,hence increasing the risk on river-bank instability(flow slides) and damage to constructions such as groynes,quays,tunnels, and *** types of mathematical models,ranging from 1D(SOBEK) to quasi-3D(Delft3D) have been applied to study the future development of the river bed and possible management *** results of these approaches demonstrate that models require inclusion of a layer-bookkeeping approach for sub-soil schematization, non-uniform sediment fractions(sand-mud),tidal and river-discharge boundary conditions,and capacity-reduction transport *** risk-reducing river management it has been shown how the development of the river bed can be addressed on a large scale and small *** instance,the use of sediment feeding and fixation of bed can be proposed for large-scale management,while monitoring and interventions at initiation of erosion can be proposed as response to small-scale developments that exceed predefined intervention levels.

关键词： River morphological modeling River-bed erodibility River management Erosion Bed stratigraphy Bank and dike stability Mathematical model

MIcROSTRUcTURE OF Mg-6.4Zn-1.1Y ALLOY FABRIcATED BY RAPID SOLIDIFIcATION AND REcIPROcATING EXTRUSION

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Acta Metallurgica Sinica(English Letters) 2008年第1期21卷 30-36页

作者： Z.M. Zhang c.j. Xu X.F. Guo School of Materials Science ＆ Engineering Xi＇an University of Technology Xi＇an 710048 China

In order to explore the methods to prepare high-strength quasicrystal-reinforced magnesium alloys, the flakes of rapidly solidified Mg-6.4Zn-1.1 Y magnesium alloy with a thickness of 50-60μm were obtained by a melt spinning single-roller device, and the flakes were then processed into rods by reciprocating extrusion and direct extrusion. The microstructure of the alloy was analyzed by optical microscope and SEM, and the constituent phases were identified by XRD. Phase transformation and its onset temperature were determined by differential thermal analyzer （DTA）. The analysis result shows that rapid solidification for *** alloy can inhibit the eutectic reactions, broaden the solid solubility of Zn in α-Mg solute solution, and impede the formation of Mg3 Y2Zn3 and MgZn2 compounds, and thus help the icosahedral Mg3 YZn6 quasicrystal formed directly from the melt. The microstructure of the flakes consists of the α-Mg solid solution and icosahedral Mg3 YZn6 quasicrystal. Dense rods can be made from the flakes by two-pass reciprocating extrusion and direct extrusion. The interfaces between flakes in the rods can be welded and jointed perfectly. During the reciprocating extrusion and direct extrusion process, more Mg3 YZn6 compounds are precipitated and distributed uniformly, whereas the rods possess fine microstructures inherited from rapidly solidified flakes. The rods contain only two phases： α- magnesium solid solution as matrix and fine icosahedral Mg3 YZn6 quasicrystal which disperses uniformly in the matrix.

关键词： Magnesium alloy Rapid solidification Reciprocating extrusion Quasicrystal

MIcROSTRUcTURES AND PROPERTIES OF REcIPROcATINGLY EXTRUDED Mg-6.4Zn-1.1Y ALLOYS

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Acta Metallurgica Sinica(English Letters) 2008年第1期21卷 37-42页

作者： Z.M. Zhang c.j. Xu X.F. Guo School of Materials Science ＆ Engineering Xi＇an University of Technology Xi＇an 710048 China

An icosahedral Mg3 YZn6 quasicrystalline phase can be produced in Mg-Zn- Y system alloys when a proper amount of Zn and Y is contained, and it is feasible to prepare the quasicrystal phase-reinforced low-density magnesium alloy. In this article, phase constituents and the effect of reciprocating extrusion on microstructures and properties of the as-cast Mg-6.4Zn-1.1 Y alloy are analyzed. The microstructure of the as-cast Mg-6.4Zn-1.1 Y alloy consists of the α-Mg solid solution, icosahedral Mg3YZn6 quasicrystal, and Mg3 Y2Zn3 and MgZn2 compounds. After the alloy was reciprocatingly extruded for four passes, grains were refined, Mg3 Y2 Zn3 and MgZn2 phases dissolved into the matrix, whereas, Mg3 YZn6 precipitated and distributed uniformly. The alloy possesses the best performance at this state; the tensile strength, yield strength, and elongation are 323.4 MPa, 258.2 MPa, and 19.7%, respectively. In comparison with that of the as-cast alloy, the tensile strength, yield strength, and elongation of the reciprocatingly extruded alloy increase by 258.3%, 397.5%, and 18 times, respectively. It is concluded that reciprocating extrusion can substantially improve the properties of the as-cast Mg-6.4Zn-1.1 Y alloy, particularly for elongation. The high performance of the Mg-6.4Zn-1.1 Y alloy after reciprocating extrusion can be attributed to dispersion strengthening and grain-refined microstructures.

关键词： Reciprocating extrusion Mg-Zn- Y alloy Icosahedral quasicrystal

DAMPING BEHAVIOR OF ULTRAFINE-GRAINED PURE ALUMINUM L2 AND THE DAMPING MEcHANISM

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Acta Metallurgica Sinica(English Letters) 2006年第3期19卷 223-227页

作者： Z.M. Zhang c.j. Xu j.c. Wang H.Z. Liu School of Materials Science ＆ Engineering Xi＇an University of Technology Xi＇an 710048 Ghina State Key Laboratory of Solidification Processing Northwestern Polytechnical University Xi＇an 710072 Ghina

Ultrafine-grained pure aluminum L2 with a mean grain size of 1.01μm was produced by equal channel angular pressing （EcAP） and annealing at 150℃ for 2h. Damping behavior of the alloy was measured using a dynamic mechanical thermal analyzer. The alloy had an excellent damping capacity Q^-1 with the ambient value being 9.8×10^-3 at 1.0Hz when the strain amplitude was 2.0×10^-5. The damping behavior of the alloy showed a non-linear damping variation tendency, that is, with an increase in temperature and a decrease of frequency, the damping capacity of the alloy increased. The damping capacity increased with the strain amplitude when the strain amplitude was less than 4.6×10^-5. When the strain amplitude was higher than 4.6×10^-5, the damping capacity became a constant and independent of strain amplitude. The high damping capacity was attributed to dislocation unpinning and a drag of dislocation on pinning points.

关键词： EcAP ultrafine grain damping capacity aluminum alloy

Phenotypic nutrient up-take differences in an alley cropping system in semi-arid Machakos, Kenya

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journal of Environmental Sciences 2001年第2期13卷 164-169页

作者： D.N. Mungai c.L.coulson c.j. Stigter j.K. Ng’ang’a D.N.Mugendi Department of Geography University of NairobiNairdbiKenya Department of Botany University of NairobiNairobiKenya Department of Enviromnental Sciences Graduate School of Productian EcologyWageningen UniversityDuivendaal 26701 APThe Netherlands Department of Meteorology University of NairobiNairobiKenya Kenya Forestry Research Instiute(KEFRI NairobiKanya)

Alley cropping of cassia siamea and maize was studied in semi arid Kenya for soil fertility improvement. Katumani composite maize was planted except in the short rains of 1988 (SR88) when a hybrid variety was sown. Therefore the grain yield per row increased differently in the alley cropped maize (cM). Sole maize (SM) and cM yields were higher in SR88 than in the long rains of 1988 (LR88) by 62% and 38%, while yields from the same treatments in LR89 were only 21% and 45% of those in SR88 These differences in relative maize yields are attributed to differences between the two maize varieties in competition under nutrient stress conditions.

关键词： alley cropping cassia siamea maize nutrients maize yield semi arid condition soil moisture Kenya

EFFEcTS OF La ON STRUcTURE AND PROPERTIES OF HEAVY RAIL STEEL

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Acta Metallurgica Sinica(English Letters) 2005年第6期18卷 701-706页

作者： c.j. Liu M.F. jiang Y.S. Wang j.j. chen c.L. Li Northeastern University Shenyang 110004 China Baotou Iron and Steel Group Gorporation Baotou 014010 Ghina

The mechanisms of La in heavy rail steel were studied by means of experimental measurements, microstructure observation and theoretical analysis in the present work. For heavy rail steel, the state and the content of La were measured, and the mechanisms and the effects of La on sulfide inclusions, microstracture and properties of steel were determined. Strip-like sulfides disappear in heavy rail steel with La/（O＋S）〉3.50, which is shown that the metallurgical function of modifying sulfide inclusions has been achieved by La. La can fine the grain size of the austenite in heavy rail steel. Under the experimental condition, the plasticity and the impacting toughness of heavy rail steel with 0.005wt% La can evidently be improved.

关键词： rare earth heavy rail steel microscopic structure sulfide inclusion,property