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Phase structure and hydrogen storage properties of LaMg_(3.93)Ni_(0.21) alloy

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Journal of Rare Earths 2012年第6期30卷 534-539页

作者：裴立超韩树民扈琳赵鑫刘岩青 State Key Laboratory of Metastable Materials Science and Technology Yanshan University College of Environmental and Chemical Engineering Yanshan University

The phase structure and hydrogen storage property of LaMg3.93Ni0.21 alloy were studied. XRD and SEM results exhibited that LaMg3.93Ni0.21 alloy consisted mainly of LaMg3, La2Mg17 and LaMg2Ni phases; after hydriding/dehydriding process, all the three phases transformed, La3H7 phase existed and the actual hydrogen absorption phases were Mg and Mg2Ni phases. Pressure-composition-temperature （P-C-T） measurement showed that the reversible hydrogen storage capacity of LaMg3.93Ni0.21 alloy was 2.63 wt.%, and the absorption time for reaching 90% of the storage capacity was 124 s at 523 K, and it was 1850 s for deabsorbing 90% of the maximum dehydrogen capacity. The hydriding process of LaMg3.93Ni0.21 alloy followed the nucleation and growth mechanisms. The enthalpy and entropy for hydriding and dehydriding reactions of the Mg phase in LaMg3.93Ni0.21 alloy were calculated to be 456.38±1.10 kJ/mol H2, -100.96±1.96 J/（K·mol） H2 and 68.50-x3.87 kJ/mol H2, 98.28 ±5.48 J/（K-mol） H2, respectively. A comparison of these data with those of MgHz （-74.50 kJ/mol H2, -132.30 J/*** H2） suggested that the hydride of LaMg3.93Nio.21 alloy was less stable than MgH2. The existence of La hydride and synergetic effect of multiphase led to higher reversible hydrogen storage capacity and better kinetic property at lower temperature for LaMg3mNi0.21 alloy.

关键词： hydrogen storage alloy phase transition hydriding kinetic thermodynamic property microstructure rare earths

Investigations on hydrogen storage properties of LaMg_(8.52)Ni_(2.23)M_(0.15) (M=Ni, Cu, Cr) alloys

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Journal of Rare Earths 2013年第1期31卷 79-84页

作者：石和韩树民贾彦虹刘岩青赵鑫刘宝忠 State Key Laboratory of Metastable Materials Science and Technology Yanshan University College of Environmental and Chemical Engineering Yanshan University

LaMg8.52Ni2.23M0.15 （M=Ni, Cu, Cr） alloys were prepared by induction melting. X-ray diffraction showed that all the three alloys had a multiphase structure, consisting of La2Mg17, LaMg2Ni and Mg2Ni phases. Energy dispersive X-ray spectrometer results revealed that most of Cu and Cr distributed in MgzNi phase. La2Mg17 and LaMg2Ni phases decomposed into MgHz, Mg2NiH4 and LaH3 phases during the hydrogenation process. Hydriding/dehydriding measurements indicated that the reversible hydrogen storage capacities of Mg2Ni phase in LaMgs.52Ni2.23M0.15 （M=Cu, Cr） alloys increased to 1.05 wt.% and 0.97 wt.% from 0.79 wt.% of Mg2Ni phase in LaMgs.52Ni2.38 alloy at 523 K. Partial substitution of Cu and Cr for Ni decreased the onset dehydrogenation temperature of the alloy hydrides and the temperature lowered by 18.20 and 5.50 K, respectively. The improvement in the dehydrogenation property of the alloys was attributed to that Cu and Cr decreased the stability of Mg2NiH4 phase.

关键词： hydrogen storage material La-Mg-Ni-based alloy microstrueture thermodynamics property hydriding kinetics rare earths

A low-threshold nanolaser based on hybrid plasmonic waveguides at the deep subwavelength scale

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Chinese Physics B 2015年第7期24卷 441-447页

作者：李志全朴瑞琦赵晶晶孟晓云童凯 Institute of Electrical Engineering Yanshan University

A novel nanolaser structure based on a hybrid plasmonic waveguide is proposed and investigated. The coupling between the metal nanowire and the high-index semiconductor nanowire with optical gain leads to a strong field enhancement in the air gap region and low propagation loss, which enables the realization of lasing at the deep subwavelength *** optimizing the geometric parameters of the structure, a minimal lasing threshold is achieved while maintaining the capacity of ultra-deep subwavelength mode confinement. Compared with the previous coupled nanowire pair based hybrid plasmonic structure, a lower threshold can be obtained with the same geometric parameters. The proposed nanolaser can be integrated into a miniature chip as a nanoscale light source and has the potential to be widely used in optical communication and optical sensing technology.

关键词： surface plasmon hybrid plasmonic waveguides nanolasers

Effect of RE on molybdenum partitioning and resultant mechanical and microstructural behavior of a duplex stainless steel during hot working condition

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Journal of Rare Earths 2015年第1期33卷 107-112页

作者：陈雷马筱聪王明家薛红燕 National Engineering Research Center for Equipment and Technology of Cold Strip Rolling Yanshan University School of Mechanical Engineering Yanshan University State Key Laboratory of Metastable Materials Science and Technology Yanshan University

The effect of rare earth（RE） on Mo partitioning and resultant mechanical and microstructural behavior of a duplex stainless steel during hot working condition was investigated. It was found that RE effect was sensitive to temperature. At the high temperature, the development of dynamic recovery（DRV） in α phase was slowed down while the dynamic recrystallization（DRX） process in γ phase was accelerated by RE, whereby both work hardening rate（at low strain） and dynamic softening rate（at high strain） increased and moreover, the discrepancy on the hardness of the both phase reduced. Whereas at the low temperature, the effect of RE was opposite as compared with those in the high temperature. Mo partitioning analysis by EPMA indicated that RE enhanced the partitioning of Mo in α phase while reduced Mo concentration in γ phase at higher temperature whereby the mismatch between two phases could be improved indicated by the elimination of voids and cracks at α/γ interface, but it was contrary to that at the low temperature. Mo partitioning was believed to be an important cause for the RE effect on the differences of mechanical and microstructural behavior. Also this result provided a reasonable evidence for micro-alloying of RE in DSSs.

关键词： duplex stainless steel rare earths partitioning hot working

Structure and electrochemical characteristics of LaNi_5-Ti_(0.10)Zr_(0.16)V_(0.34)Cr_(0.10)Ni_(0.30) composite alloy electrode

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Journal of Rare Earths 2010年第5期28卷 774-780页

作者：王艳芝赵敏寿 College of Environmental and Chemical Engineering Yanshan University State Key Laboratory of Metastable Materials Science and Technology Yanshan University

Composite LaNi5+x wt.% Ti0.10Zr0.16V0.34Cr0.10Ni0.30 (x=0, 1, 5, 10) alloys were prepared by two-step re-melting. X-ray diffractometer (XRD), scanning electron microscopy (FESEM), energy dispersive spectrometry (EDS), inductively coupled plasma (ICP) and electrochemical impedance spectroscopy (EIS) analyses showed that the matrix phase of LaNi5 alloy with CaCu5 structure remained unchanged after additive alloy was added, the amount of the second phase increased with increasing x. The synergetic effect withi...

关键词： Ni/MH battery metal hydride electrode composite alloy electrochemical properties kinetic properties rare earths

High temperature electrochemical discharge performance of LaFeO3 coated with C/Ni as anode material for NiMH batteries

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Progress in Natural Science:Materials International 2022年第6期32卷 684-692页

作者： Kailiang Ren Jiajia Miao Wenzhuo Shen Huanhuan Su Yunpeng Pan Jiajin Zhao Xiangyu Pan Yuan Li Yaokun Fu Lu Zhang Shumin Han State Key Laboratory of Metastable Materials Science and Technology Yanshan University School of Environmental and Chemical Engineering Yanshan University

Perovskite LaFeO3is considered as a promising new anode material for nickel/metal hydride batteries due to its low cost,environmental friendliness and high temperature ***,the poor conductivity of LaFeO3material restricts the discharge ability,which is problematic for its future widespread *** solve the above issue,in this study,we prepared C/Ni-coated LaFeO3composite in view of the excellent electrical conductivity of carbon and nickel *** show that the C/Ni-coated LaFeO3composite delivers remarkably increased discharge capacity of ～345 mAh g-1at 60℃ in contrast to ～267 mAh g-1for pure ***,the carbon and nickel not only increase the electrical conductivity of the LaFeO3but also reduces the agglomeration of the LaFeO3,therefore,the C/Ni-coated LaFeO3composite serves superior long cycle-life,which maintains 60.9% after 100 cycles(52.9% for the LaFeO3sample).In overall,the electrochemical behavior of the C/Ni-coated LaFeO3composite confirms its high potential as nickel/metal hydride batteries for energy storage applications.

关键词： Energy storage Perovskite-type oxide Nickel metal hydride batteries LaFeO 3 Electrochemical performance

Comparisons of Exhaustive and Nonexhaustive M/M/l/N Queues with Working Vacation and Threshold Policy

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Journal of Systems Science and Systems Engineering 2019年第2期28卷 154-167页

作者： Wei Sun Shiyong Li Yan Wang Naishuo Tian School of Economics and Management Yanshan UniversityQinhuangdao 066004 China College of Science Yanshan University Qinhuangdao 066004 China

This paper compares the performance of exhaustive and nonexhaustive M/M/l/N queues with working vacation and threshold policy. In an exhaustive queue, the server slows down its service rate only when no customers exist in the system, and turns to normal service until the number of customers achieves a threshold. However, in a nonexhaustive queue, the server switches service rate between a low and a high value depending on system congestion. To get equilibrium arrival rate of customers and social welfare for the two types of queues, we first derive queue length distributions and expected busy circle. Then, by making sensitivity analysis of busy circle, system cost, arrival rate and optimal social welfare, we find that customers tend to join exhaustive queues instead of nonexhaustive queues, and the optimal threshold in an exhaustive queue is probably inconsistent with the one in a nonexhaustive queue. Moreover, in general, whet her to consider system cost or not in social welfare will obviously affect the tendencies of optimal arrival rate and optimal social welfare with the threshold and system capacity for the two types of queues, especially for the nonexhaustive queues, and then affect the final decisions of social planner or system manager.

关键词： Markovian queue service discipline limited capacity working vacations threshold policy equilibrium arrival rate busy circle social welfare system cost

Fluid Model Modulated by an M/M/1 Working Vacation Queue with Negative Customer

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Acta Mathematicae Applicatae Sinica 2018年第2期34卷 404-415页

作者： Xiu-li XU Xian-ying WANG Xiao-feng SONG Xiao-qing LI College of Science Yanshan University

This paper investigates a fluid model driven by an M/M/1 queue with working vacations and RCE （Removal of customer in the end） policy of negative customer. In the external environment, the negative customer is not served by the server and only removes the positive customer in the end one-to-one. We establish a fluid flow model based on this stochastic process, and obtain the mean buffer content and the probability of empty buffer for this fluid queue using the LT （Laplace transform） method. Moreover, several special cases of the model here are obtained. Finally, some numerical examples are presented to demonstrate the effects of parameters on the performance indices of the fluid model.

关键词： fluid model negative customer RCE (Removal of customer in the end) policy buffer content LT(Laplace transform)

Rare Earth Doped Optical Fibers for Temperature Sensing Utilizing Ratio-Based Technology

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Journal of Rare Earths 2006年第Z2期24卷 171-174页

作者：王玉田耿丽琨 Electrical Engineering Institute Yanshan University

A new and practical fluorescence temperature detecting system based on fluorescence intensity ratio was proposed . The background theory of fluorescence intensity-ratio method was presented simply. And the characters of rare earth doped samples were detailed. The erbium-doped fiber was chosen as the sensing element. The energy levels of 2H11/2 and 4S3/2 are responsible for the emission of radiation at approximately 530 and 555 nm. The erbium-doped (960 ppm) fiber of length 20 cm and core diameter 3.2μm was used as the sensing part. A silica photodiode transfers the fluorescence signal to electric signal, then the ratio of the average of the two different signals was calculated by the computer and the temperature was obtained. The ratio R of the intensity resulting from the transition between the two levels varies proportionly with temperature interval from 293 K to 373 K. The sensitivity of the sensor is approximately 0.05 K-1.

关键词： fluorescence intensity ratio rare-earth doped material temperature detecting optical fiber