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Particle interaction during magnetization reversal process of anisotropic Sm_2Fe_(17)N_x powders

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Rare Metals 2018年第10期37卷 875-880页

作者： Ci-Fu Lu Xiu-Feng Hong Xiao-Qian Bao xue-xu gao Jie Zhu State Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing

The particle interaction during magnetization reversal process is important for the applications and magnetic properties improvement of Sm2Fe17Nx powders. In this paper, an anisotropic Sm2Fe17Nx powder free of α- Fe was prepared by ball milling. The magnetically soft Sm2Fe17 powders with different particle sizes were added into the α-Fe-free SmaFe17Nx powder as easy nucleation sites, and the effects of these magnetically soft phases on the magnetization reversal process were investigated quantitatively. It is found that the squareness of Sm2Fe17Nx powder decreases obviously with the increasing number of Sm2Fe17 particle and the demagnetization curves can be divided into two stages. The magnetization reversal process suggests that the addition of magnetically soft powder should only reduce the coercivity of a specific part of Sm2Fe17Nx particles and the reversed domain walls cannot move easily across neighboring Sm2Fe17Nx particles. Based on the observed magnetization reversal process, the mechanical properties of magnetically soft phase should be considered in the preparation of anisotropic Sm2Fe17Nx powders.

关键词： Rare earth permanent magnets Sm2Fe17Nx Magnetic domain behavior

Texture-based magnetostriction calculation of oriented polycrystalline cobalt ferrites

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Rare Metals 2018年第5期37卷 421-426页

作者： Ji-Quan Wang Ji-Heng Li Chao Yuan Xiao-Qian Bao xue-xu gao State Key Laboratory of Advanced Metals and Materials University of Science and Technology Beijing Beijing 100083China

Oriented polycrystalline cobalt ferrites with different alignments were prepared via a ceramic method. The maximum magnetostriction λs up to -270×10^-6 was achieved for oriented samples, when the oriented magnetic field was above 1.0 T. Textures of all samples were determined by electron back-scattered diffraction （EBSD） technique and were used to calculate magnetostriction values of oriented polycrystalline cobalt ferrite samples. Results show that a preferred 〈001〉 orientation has been obtained within oriented sample. Calculation was done by considering the magnetostriction value as the sum of the content in volume fraction-weighted single-crystal behavior along [100], [110], [210], [310], [311], [211] and [111] directions. The calculated magnetostriction values when compared with experimentally obtained values show identical behavior as a function of applied magnetization orientation field. Good consistency of change rules between calculated values and measured ones illustrates the successful application of this method in predicting magnetostriction values of polycrystalline materials.

关键词： Magnetostriction calculation Oriented polycrystalline Cobalt ferrites Texture

Enhanced hydrogen storage of alanates: Recent progress and future perspectives

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Progress in Natural Science:Materials International 2021年第2期31卷 165-179页

作者： Li Zhao Fen xu Chenchen Zhang Zhenyue Wang Hanyu Ju xu gao Xiaoxu Zhang Lixian Sun Zongwen Liu Guangxi Key Laboratory of Information Materials Guangxi Collaborative Innovation Center of Structure and Property for New Energy and Materials School of Materials Science and Engineering Guilin University of Electronic Technology School of Chemical and Biomolecular Engineering The University of Sydney The University of Sydney Nano Institute The University of Sydney

The global energy crisis and environmental pollution have caused great concern. Hydrogen is a renewable and environmentally friendly source of energy and has potential to be a major alternative energy carrier in the *** to its high capacity and relatively low cost of raw materials, alanate has been considered as one of the most promising candidates for hydrogen storage. Among them, LiAlH4and NaAlH4, as two representative metal alanates, have attracted extensive attention. Unfortunately, the high desorption temperature and sluggish kinetics restrict its practical application. In this paper, the basic physical and chemical properties as well as the hydrogenation/dehydrogenation reaction mechanism of LiAlH4and NaAlH4are briefly reviewed. The recent progress on strategic optimizations toward tuning the thermodynamics and kinetics of the alanate including nanoscaling,doping catalysts and compositing modification are emphatically discussed. Finally, the coming challenges and the development prospects are also proposed in this review.

关键词： Hydrogen storage LiAlH 4 NaAlH 4 Nanoscaling Catalysts Mechanism

Microstructure and magnetostrictive performance of NbC-doped <100>oriented Fe-Ga alloys

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International Journal of Minerals,Metallurgy and Materials 2015年第1期22卷 52-58页

作者： Chao Yuan Ji-heng Li Wen-lan Zhang Xiao-qian Bao xue-xu gao State Key Laboratory of Advanced Metals and Materials University of Science and Technology Beijing

The〈100〉oriented Fe83Ga17 alloy rods with various NbC contents less than 1at%were prepared by the directional solidification method at a growth rate of 720 mm·h^-1. Low NbC-content was found to affect the oriented grain growth and slightly improve the〈100〉ori-entation. Flat grain boundaries in the alloys with low NbC contents less than 0.2at%became greatly curved at higher NbC contents, and a large amount of Nb-rich precipitates were observed in the alloys with high NbC contents. Small amounts of NbC, less than 0.2at%, resulted in an increase in magnetostrictive strain due to the improvement of the〈100〉orientation, and a high magnetostrictive strain value of 335 ×10^-6 under a pre-stress of 15 MPa was obtained in the 0.1at%NbC-doped alloys. The magnetostrictive performance obviously decreased with the NbC addition higher than 0.5at%, and the strain sensitivity under no pre-stress was lower than that in the binary Fe？Ga alloy.

关键词： iron gallium alloys magnetostriction texture niobium carbide directional solidification

Energy consumption of electrooxidation systems with boron-doped diamond electrodes in the pulse current mode

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International Journal of Minerals,Metallurgy and Materials 2013年第1期20卷 106-112页

作者： Jun-jun Wei xu-hui gao Li-fu Hei Jawaid Askari Cheng-ming Li Institute of Advanced Materials and Technology University of Science and Technology Beijing Institute of Manufacturing Engineering National University of Sciences & Technology (NUST)

A pulse current technique was conducted in a boron-doped diamond （BDD） anode system for electrochemical waste- water treatment. Due to the strong generation and weak absorption of hydroxyl radicals on the diamond surface, the BDD elec- trode possesses a powerful capability of electrochemical oxidation of organic compounds, especially in the pulse current mode. The influences of pulse current parameters such as current density, pulse duty cycle, and frequency were investigated in terms of chemical oxygen demand （COD） removal, average current efficiency, and specific energy consumption. The results demon- strated that the relatively high COD removal and low specific energy consumption were obtained simultaneously only if the current density or pulse duty cycle was adjusted to a reasonable value. Increasing the frequency slightly enhanced the COD re- moval and average current efficiency. A pulse-BDD anode system showed a stronger energy saving ability than a constant-BDD anode system when the electrochemical oxidation of phenol of the two systems was compared. The results prove that the pulse current technique is more cost-effective and more suitable for a BDD anode system for real wastewater treatment. A kinetic analysis was presented to explain the above results.

关键词： diamond fihlls boron doping electrochemical oxidation hydroxyl radicals energy consumption wastewater treat- ment

Enhancement of magnetic properties and thermal stability of nanocrystalline (NdDyTb)_(12.3)(FeZrNbCu)_(81.7)B_(6.0) alloy with Co substitution

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International Journal of Minerals,Metallurgy and Materials 2009年第6期16卷 696-700页

作者： Xiao-qian Bao Wei Li Jie Zhu xue-xu gao Shou-zeng Zhou State Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing Beijing 100083 China College of Materials Science and Engineering Yanshan University Qirdauangdao 066004 China

The major drawbacks of Nd-Fe-B magnets are relatively low Curie temperature and poor thermal stability. Ribbons with the near stoichiometric 2：14：1 composition of Nd10.8Dy0.75Tb0.75Fe79.7-xCoxZr0.8Nb0.8Cu0.4B6.0 （x=0, 3, 6, 9, 12, 15） were prepared by rapid quenching and subsequent heat treatment. The effect of Co element on the magnetic properties, thermal stability, and microstructure of the ribbons was systematically studied by vibrating sample magnetometer （VSM）, thermal magnetic analysis, atomic force microscopy （AFM）, and transmission electron microscopy （TEM）. It was found that Co substitution was significantly effective in improving the magnetic properties and the thermal stability of nanocrystalline ribbons. Although the intrinsic coercivity decreased from 1308.7 kA/m for x=0 to 817.4 kA/m for x=15, the remanence polarization and maximum energy product increased from 0.839 T and 116.5 kJ/m^3 for the Co-free samples to 1.041 T and 155.1 kJ/m^3 for the 12at% Co-substituted samples, respectively. About 10 K increase in Curie temperature was observed for the 2：14：1 phase with 1at% Co substitution. The absolute values of temperature coefficients of induction and coercivity were significantly decreased with Co substitution, which may be attractive for high operational temperature applications. The microstructure of nanocrystalline ribbons was slightly refined with Co substitution.

关键词： nanocrystalline magnets Nd-Fe-B magnets Co substitution magnetic properties thermal stability microstructure

Secondary recrystallization of Goss texture in magnetostrictive Fe–Ga-based sheets

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Rare Metals 2020年第11期39卷 1288-1294页

作者： Chao Yuan xue-xu gao Ji-Heng Li Xiao-Qian Bao State Key Laboratory of Advanced Metals and Materials University of Science and Technology BeijingBeijing 100083China

To avoid the unfavorable effect of precipitates on magnetic properties,low addition of 0.16 wt%NbC was employed in Fe_(82.5)Ga_(17.5)alloy,and 0.27 mm sheets were successfully prepared by a rolling *** Goss texture was obtained in Fe-Ga sheets by two-stage annealing *** sulfur annealing in quartz ampoules was made to produce the preferred growth of Goss texture,with a 51%increase in the observed saturation magnetostriction,from 87×10^(-6)in the Ar-annealed sheets to 132×10^(-6)in the S-annealed ***,large amounts of S-rich and Nb-rich precipitates were formed in the S-annealed ***-temperature annealing of the S-annealed sheets at 1,200℃under a flow hydrogenargon atmosphere could effectively eliminate the precipitates and promote the selective growth of(110)grains due to the low surface *** grains(~2 cm)of secondary recrystallization were achieved in the final annealed sheets,with the maximum average saturation magnetostriction of 180×10^(-6).

关键词： Fe–Ga alloy Goss texture Magnetostriction Secondary recrystallization

Magnetostriction and magnetization of <110> oriented Tb0.27Dy0.73Fe1.95 alloys with different compressive prestresses

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Rare Metals 2020年第2期39卷 176-180页

作者： Xing Mu Hai-Jun Tang xue-xu gao Xiao-Qian Bao Ji-Heng Li State Key Laboratory for Advanced Metals and Materials University of Science and Technology BeijingBeijing100083China China Academy of Civil Aviation Science and Technology Beijing100028China

oriented Tb0.27Dy0.73Fe1.95 alloys were studied under different applied compressive *** saturation magnetostriction by 500×10-6 is obtained for the sample under 5 MPa than that under no applied *** understand the effect of prestress on the magnetostrictive coefficient,differential magnetostrictive coefficient,relative permeability and coercive force were studied in *** results show that the maximum differential magnetostrictive coefficient is about 37 x 10-9 m·A-1,about two times that without *** addition,the saturation magnetostriction coefficient increases gradually with the stress increasing,while the maximum differential magnetostrictive coefficient *** saturation inductions under different stresses are similar to a value of about 1.1 *** relative permeability decreases with stress increasing.

关键词： Tb-Dy-Fe Compressive prestress Magnetostriction

Development of a LiFePO_(4)-based high power lithium secondary battery for HEVs applications

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Rare Metals 2020年第12期39卷 1457-1463页

作者： Long-Zheng Deng Feng Wu xu-Guang gao Wei-ping Wu Beijing Key Laboratory of Environmental Science and Engineering School of Chemical Engineering and the Environment Beijing Institute of TechnologyBeijing 100081China National&Local United Engineering Laboratory for Power Battery Department of ChemistryInstitute of Functional Material ChemistryNortheast Normal UniversityChangchun 130024China

A LiFeP04-type lithium secondary battery cell of 8 Ah capacity with a high energy density and power density was developed for hybrid electric vehicle(HEV)applications by optimizing the key raw materials and process *** 8 Ah class LiFePO_(4)cell with an energy density of 77.2 Wh·kg^(-1)exhibits a power density of 2818 W·kg^(-1)at 50%SOC(state of charge).The battery shows good cyclic capability with the capacity retention of 81.1%after 1,870 cycles at 5 C charge and 10 C discharge *** is demonstrated that the cells have an excellent balance of high-power,high-energy,low temperature,and long-life performance for meeting the requirements of HEV.

关键词： Li-ion battery Lithium iron phosphate High-power Long-life Hybrid electric vehicle