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设计了一套金属有机骨架(MOFs)材料低温储氢性能测试装置。该装置的设计压力为10MPa,可以在低温宽温区范围内对多种金属有机骨架材料的低温储氢性能进行测试,且样品更换方便。此外,还介绍了试验的原理及步骤。 相似文献
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设计了一种用于研究金属有机骨架(MOFs)材料低温储氢性能的低温恒温器。介绍了其设计原理及具体结构。该低温恒温器能够为多种MOFs材料提供低温宽温区范围内的温度环境,且样品更换方便。 相似文献
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以熔化-旋转法制备了Cu70Zr30和Cu100-xYx( x = 28, 67)非晶带试样并在1~300 K温度范围内测量了电阻和磁电阻随温度变化的规律.非晶Cu70Zr30电阻率ρ(T)的温度系数(TCR)在整个测量温区内都是负值,并且在两个不同的温区表现出-T1/2行为.对于类似的Cu100-xYx合金系统,在1~200 K温区内也做了同类测量.在低温1~4 K, 两个不同的无序系统CuZr和CuY的 TCR都准确地表现出-T1/2行为,这表明无序系统在极低温条件下的量子相干效应.这主要应归因于在粒子-空穴通道的电子-电子相互作用.而无序Cu70Zr30在宽广的中低温区60~300 K以更大斜率表现出的-T1/2行为,可以用初始定域化理论解释.无序CuZr和CuY的低温磁电阻ρ(B,T)测量结果与定域化理论进行了拟合和讨论. 相似文献
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氦-3状态方程研究进展第一部分:固-液、气-液饱和线以及临界区状态方程 总被引:1,自引:0,他引:1
宽温度和压力范围内的3He详细热力参数数据对进行极低温基础科学研究和制冷特性研究是至关重要的,但至今尚缺乏一个热力学统一的解析形式状态方程来准确描述1K左右到室温300K温区的3He热力学性质.在收集和整理各类研究3He热力性质文献的基础上,总结了3He固-液、气-液饱和线以及临界区状态方程的研究状况.这项工作不仅能为关心3He局部区域性质的研究人员提供总结,而且可为今后开发宽范围的3He热力学状态方程提供参考. 相似文献
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用助溶剂方法高温烧制了电子型超导体母体材料Nd2CuO4及其微量Zn掺杂的单晶样品,并系统地研究了在15-300K范围内样品的电阻率和热电势行为.两者在25-200K之间的温区都表现相同的物理行为—高温区为半导体热激活行为,低温区为二维变程跳跃行为.在206K附近发现了反铁磁转变对热电势行为影响的精细峰和弛豫现象.我们的实验结果表明在180K以上温区载流子的行为不满足传统的能带理论.退火对25K以下的温区的热电势的行为有非常显著的影响,其本征的物理性质还需要深入的研究. 相似文献
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用助溶剂方法高温烧制了电子型超导体母体材料Nd2CuO4及其微量Zn掺杂的单晶样品,并系统地研究了在15~300K范围内样品的电阻率和热电势行为.两者在25~200K之间的温区都表现相同的物理行为高温区为半导体热激活行为,低温区为二维变程跳跃行为.在206K附近发现了反铁磁转变对热电势行为影响的精细峰和弛豫现象.我们的实验结果表明在180K以上温区载流子的行为不满足传统的能带理论.退火对25K以下的温区的热电势的行为有非常显著的影响,其本征的物理性质还需要深入的研究. 相似文献
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在2—30K温度范围内,测量了国产RS-11实芯炭电阻的电阻-温度曲线,其室温阻值分别为200欧、100欧、50欧、10欧.结果表明:国产实芯炭电阻可以在这个温区内作低温温度计,其4.2 K时的重复性优于0.1K,长时间(5天内)浸泡于液氦中的稳定性优于20mK. 相似文献
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设计了一套温控系统,用在金属有机骨架(MOFs)材料低温储氢性能测试装置上.测试装置以循环液氮作为冷源.根据测试装置内的温度信号,温控系统利用PID温控仪,并结合继电器对加热丝的加热量进行调节,满足测试装置所需的温度范围,并能恒定在某一测试温度下.所设计的温控系统可以实现低温宽温区范围内的连续调节,且系统简单、操作方便... 相似文献
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用固相反应法制备La4/5Sr1/5MnO3及在其A位分别掺K、Ag系列样品,通过X射线衍射(XRD)谱,电阻率-温度(ρ~T)曲线,磁电阻-温度(MR~T)曲线,研究了在A位同时掺入一价、二价元素而保持Mn3+/Mn4+比值(摩尔比n(A)/n(B))不变的钙钛矿锰氧化物体系A位离子半径及A位离子的无序度σ2对电输运性质及磁电阻的影响.结果表明:A位离子的无序度σ2对电输运性质的影响比A位平均离子半径对电输运性质的影响大;电阻率曲线出现双峰是由于表面相电阻率与体相电阻率竞争的结果;MR的温度稳定性是本征磁电阻与隧穿磁电阻竞争的结果;掺K样品在253~175K温区MR从8.1%缓慢上升到9.5%,掺Ag样品在260K以下温区MR都在7.4%以上,纯的La4/5Sr1/5MnO3样品在318~259K温区MR都在7.0%以上,在如此宽温区MR几乎不变有利于MR的实际应用. 相似文献
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氢在A、X及ZSM-5型沸石上的高压物理吸附 总被引:1,自引:0,他引:1
采用常规体积吸附装置测定了77、195、293K和7MPa的条件下氢在A、X及ZSM-5沸石上的吸附特性和吸附容量.所有的氢吸附等温线基本符合Ⅰ型等温线,但在77K,压力为2-5MPa的等温线上观察到了超临界高压吸附所特有的最大吸附量.从等温线确定了等量吸附热并讨论了其影响因素.根据骨架结构和所含阳离子类型的差异,各种沸石表现出不同的氢吸附量.其中NaX沸石在77K/4MPa下的重量储氢分数为2.55%,是该实验中所测得的最高吸附量.CaA、NaX和ZSM-5沸石的氢吸附量与其比表面积成正比,这与沸石中的可用空穴容积有关.然而NaA和KA沸石不存在这种线性关系.实验中还观察到,NaA与KA沸石间出现氢吸附量的临界值是由KA沸石中较大的阳离子堵塞效应引起的.该实验将吸附质分了的动力学直径与沸石主晶孔的有效直径之比用于判断物理吸附中的堵塞效应. 相似文献
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采用巨正则系综蒙特卡罗方法, 通过含有此方法模块的GULP软件, 系统地研究了扶手椅式单壁碳纳米管在低温和常温下的储氢性能, 给出了5种半径的扶手椅管在液氮温度(77 K)和常温(280 K)下的吸附等温线, 同一管径在不同温度不同压强下氢分子在碳纳米管中的分布构型图等. 对77 K和280 K下不同压强不同管径的碳纳米管储氢能力做了较为全面的对比分析, 最后根据模拟计算的结果, 对碳纳米管储氢能力的强化提出了一些建设性意见. 相似文献
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The sorption of hydrogen on carbon structures and nanostructures offers a way to reduce the storage pressure of hydrogen with respect to compression storage while achieving interesting gravimetric storage densities. The most readily available carbon structures, activated carbons, can achieve reproducible, high gravimetric storage densities under cryogenic operating conditions: 5–6% at 35 bar and 77 K, in excess of the normal density that would be present in the pore volume under compression at the same temperature and pressure. We discuss and compare the adsorption of hydrogen on high specific surface activated carbons, nanofibres and nanotubes from experimental and theoretical considerations. In particular, we present gravimetric and volumetric hydrogen sorption measurements on single-walled carbon nanotubes (SWNTs) at (1 bar, 77 K) and (1 bar, 295 K) within the context of our ongoing work on the storage of hydrogen on activated carbon and carbon nanostructures. BET surface area and XRD characterization results on SWNTs are also presented. The experiments were performed on as received, chemically treated and metal-incorporated SWNT samples. Hydrogen sorption capacities measured on treated samples ranged from 0 to about 1 wt.% at 1 bar and 295 K and reached about 4 wt.% at 1 bar and 77 K. Our results show that under certain conditions, SWNTs have better hydrogen uptake performance than large surface area activated carbons. PACS 81.07.de; 81.05.Uw; 68.43.h 相似文献
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Preparation and hydrogen storage of activated rayon-based carbon fibers with high specific surface area 总被引:1,自引:0,他引:1
Activated carbon fibers were prepared from rayon-based carbon fibers by two step activations with steam and KOH treatments. Hydrogen storage properties of the activated rayon-based carbon fibers with high specific surface area and micropore volume have been investigated. SEM, XRD and Brunauer-Emmett-Teller (BET) were used to characterize the samples. The adsorption performance and porous structure were investigated by nitrogen adsorption isotherm at 77 K on the base of BET and density functional theory (DFT). The BET specific surface area and micropore volume of the activated rayon-based carbon fibers were 3144 m2/g and 0.744 m3/g, respectively. Hydrogen storage properties of the samples were measured at 77 and 298 K with pressure-composition isotherm (PCT) measuring system based on the volumetric method. The capacities of hydrogen storage of the activated rayon-based carbon fibers were 7.01 and 1.46 wt% at 77 and 298 K at 4 MPa, respectively. Possible mechanisms for hydrogen storage in the activated rayon-based carbon fibers are discussed. 相似文献
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Seifollah Jalili Arezou Jaberi Mohammad Ghasem Mahjani Majid Jafarian 《Molecular physics》2013,111(6):361-368
Utilising molecular dynamics simulations, the hydrogen molecules adsorption isotherms of the (8,?0) palladium decorated single-walled carbon nanotube (SWNT) were obtained. The hydrogen adsorption was studied on the external, interstial and internal surfaces of the SWNT bundle at several temperatures ranging from 77 to 400?K. The results were compared with the bare single-walled carbon nanotube bundle under the same conditions. The decorated carbon nanotube bundle hydrogen adsorption was significantly higher than that of the bare one. The hydrogen desorption and readsorption were studied using temperature as the readsorption/desorption variable. The rate constants were calculated for the hydrogen desorption at different temperatures. The calculated decorated SWNT bundle hydrogen desorption activation energy was higher than that for the bare SWNT bundle. The calculated activation energies for the hydrogen desorption in both nanotube bundles specified the temperature dependency of hydrogen desorption. 相似文献
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V. V. Zubkov V. M. Samsonov I. V. Grinev 《Bulletin of the Russian Academy of Sciences: Physics》2012,76(7):814-818
The hydrogen adsorption in slit-shaped pores of carbon adsorbents is investigated using the density functional theory. Hydrogen adsorption in the gap between two monocarbon (graphene) walls is calculated for 20.33, 77, and 200 K. At T = 20.38 and 77 K, our data on the hydrogen storage capacities in slit pores are in good agreement with the results of A.A. Fomkin and V.A. Sinitsyn [23], obtained using Dubinin’s volume pore filling theory and the standard data on benzene adsorption. Under supercritical conditions, the adsorption capacity in the modeling adsorbents is underestimated by half. 相似文献