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Preparation of Sm_2Fe_(17) alloy by reduction-diffusion process

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Rare Metals 2018年第11期37卷 989-994页

作者： Hai-Bo Chen Jing-Wu Zheng Liang Qiao Yao Ying Li-Qiang Jiang Sheng-Lei Che Research center of magnetic and Electronic materials College of Materials Science and Engineering Zhejiang University of Technology

SmFealloy is the intermediate material for the preparation of SmFeNx(x ≈ 3); thus, the synthesis of pure SmFemother alloy is the key to obtaining highperformance SmFeNx. Reduction-diffusion(R-D) is a cost-effective method. In this study, the R-D process of synthesizing SmFewas analyzed by scanning electron microscopy(SEM), energy-dispersive X-ray spectroscopy(EDX), X-ray diffraction(XRD), and X-ray fluorescence(XRF). Furthermore, the influences of the tightness of compacted reactants, the compensation amount of SmO,and the particle size of Fe on the formation of SmFewere discussed from the aspects of the three raw *** results show that Sm reduced from SmOreacts with Fe particles to form intermetallic compound SmFedirectly in the R-D reaction process of preparing SmFe;the generation of Sm and its migration to the surface of Fe particles control the reaction rate; a proper tightness of compacted reactants is necessary for ensuring the purity of SmFeproduct; pure SmFecan be obtained when the compensation of SmOis 33 % of the stoichiometry; and the sufficiency of the reaction improves with the decrease in the size of Fe powders under the same reaction condition.

关键词： Sm_2Fe_(17) Reduction-diffusion Rare earth Permanent magnet

Magnetostrictive Properties for Epoxy Bonded Tb_(1-x)Dy_xFe_2 Composites

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Journal of Rare Earths 2003年第S1期21卷 155-158页

作者：王博文李淑英闫荣格曹淑英翁玲 Research center of magnetic Technique and magnetic materials Hebei University of Technology School of Science Tianjin University of Technology

The epoxy bonded Tb_(1- x )Dy_ x Fe_2 composites were prepared. The magnetostriction,dynamic magnetostrictive coefficient and magnetomechanical coupling coefficient of epoxy bonded Tb_(1- x )Dy_ x Fe_2 rod samples were measured by using multiple parameter magnetic measurement system. It is found that the magnetostriction,dynamic magnetostrictive coefficient and magnetomechanical coupling coefficient of epoxy bonded Tb_(0.3)Dy_(0.7)Fe_2 rod sample are higher than those reported. The reason for the high magnetostrictive properties of the sample was explained according to the theory of magnetization process. The result indicates that the epoxy bonded Tb_(0.3)Dy_(0.7)Fe_2 rod sample is of practical value.

关键词： magnetic material magnetostrictive property rod composite Terfenol-D rare earths

Corrosion mechanism of H_2O on Sm_2Fe_(17) and nitrogenation process of corroded Sm_2Fe_(17)

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Journal of Rare Earths 2019年第6期37卷 638-644页

作者： Jianwei Xu Jingwu Zheng Haibo Chen Liang Qiao Yao Ying Wei Cai Wangchang Li Jing Yu Min Lin Shenglei Che Research center of magnetic and Electronic materials College of Materials Science and EngineeringZhejiang University of Technology Key Laboratory of magnetic materials and Devices Ningbo Institute of Material Technology & EngineeringChinese Academy of Sciences

Sm_2 Fe_(17) prepared by reduction-diffusion method needs to be washed with water to remove calcium oxide. Electrochemical corrosion occurs when Sm_2 Fe_(17) powder is in contact with liquid water. Corrosion mechanism of H_2 O on Sm_2 Fe_(17) powder and nitrogenation process of corroded Sm_2 Fe_(17) were studied by analyzing the structure and morphology. It is indicated that the metallic hydroxide forms and deposits on the Sm_2 Fe_(17) powder surfaces during water corrosion. At the same time, oxygen and hydrogen enter the unit cell of Sm2 Fe_(17), causing a slight increase in Curie temperature. In the subsequent nitriding process,the hydroxide is dehydrated and hydrogen is desorbed. The resulting oxide reacts with Sm_2 Fe_(17)N_x to form a-Fe and Sm_2 O_3. Thermodynamic calculations using the HSC Chemistry 6.0 software indicate that the reaction can occur spontaneously. The effect of water corrosion on the magnetic properties of the nitride can be eliminated by hydrogen reduction prior to nitriding.

关键词： Sm2Fe17 Nitrogenation Reduction-diffusion method Water corrosion α-Fe formation Rare earths

Micromagnetic simulations of reversal magnetization in cerium-containing magnets

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Chinese Physics B 2019年第3期28卷 351-356页

作者： Lei Li Shengzhi Dong Hongsheng Chen Ruijiao Jiang Dong Li Rui Han Dong Zhou Minggang Zhu Wei Li Wei Sun Division of Functional materials Research Central Iron and Steel Research Institute National Engineering Research center for magnetic materials

Single-grain models with different cerium contents or structural parameters have been introduced to investigate the reversal magnetization behaviors in cerium-containing magnets. All the micromagnetic simulations are carried out via the object oriented micromagnetic framework(OOMMF). As for single(Nd,Ce)_2 Fe_(14)B type grain, the coercivity decreases monotonously with the increase of the cerium content. Four types of grain structure have been compared: single(Nd,Ce)_2 Fe_(14)B type, core((Nd,Ce)_2 Fe_(14)B)-shell(Nd_2 Fe_(14)B) type with 2 nm thick shell, core(Ce_2 Fe_(14)B)-shell(Nd_2 Fe_(14)B) type, and core(Nd_2 Fe_(14)B)-shell(Ce_2 Fe_(14)B) type. It is found that core((Nd,Ce)_2 Fe_(14)B)-shell(Nd_2 Fe_(14)B)type grain with 2 nm thick shell always presents the largest coercivity under the same total cerium content. Furthermore,the relationship between the coercivity and the shell thickness t in core((Nd,Ce)_2 Fe_(14)B)-shell(Nd_2 Fe_(14)B) type grain has been studied. When the total cerium content is kept at 20.51 at.%, the analyzed results show that as t varies from 1 nm to 7 nm, the coercivity gradually ascends at the beginning, then quickly descends after reaching the maximum value when t = 5 nm. From the perspective of the positions of nucleation points, the reasons why t affects the coercivity are discussed in detail.

关键词： micromagnetic simulation cerium-containing magnets core-shell structure coercivity

Development of high-performance dry-pressed anisotropic permanent ferrite for La-Ca-Sr-Co system

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Rare Metals 2020年第1期39卷 89-94页

作者： Dai-Man Zhu Zhao-Wen Geng Rong-Ming Liu Xiao-Wen Zhou Li-Ying Jia Guo-Hui Hu Qian Wang Bing-Shan Li National Engineering Technology Research center for magnetic materials BGRIMMBeijing102600China BGRIMM magnetic materials and Technology(Fuyang)Co. Ltd.Fuyang236000China

In this work,the BMS-12 pre-sintered material was used as the basic material,and the optimal secondary additive addition amount was found by the wet pressing ***,the anisotropic ferrite material was prepared by dry-pres sing method,and the effects of camphor adhesives,calcium stearate lubricant and powder particle size on the magnetic properties were *** experimental results show that the appropriate addition amount of camphor adhesive and calcium stearate lubricant is 0.6 wt%and 0.8 wt%,*** remanence and coercivity can be obtained for particle size of 0.85-1.00μ*** dry-pressed magnet ferrite was prepared with typical properties of magnetic induction intensity of Br=421 mT,induction coercivity of Hcb=296 kA·m-1,intrinsic coercivity of Hcj=369 kA·m-1 and maximum energy product of(BH)max=33.3 kJ·m-3,which have reached the level of TDK corporation product of FB5 *** shows that the dry-pressed magnet of La-Ca-Sr-Co system has higher remanence and intrinsic coercivity than the traditional wetpressed Sr-ferrite.

关键词： Dry-press molding Permanent magnetic ferrite La-Ca-Sr-Co system magnetic properties

Anomalous magnetic property and broadband photodetection in ultrathin non-layered manganese selenide semiconductor

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Nano Research 2024年第9期17卷 8578-8584页

作者： Ye Zhao Ruilong Yang Ke Yang Jiarui Dou Xiaoting Yang Jinzhong Guo Guowei Zhou Xiaohong Xu School of Chemistry and materials Science Key Laboratory of Magnetic Molecules and Magnetic Information Materials of Ministry of EducationShanxi Normal UniversityTaiyuan 030006China Research Institute of materials Science Collaborative Innovation Center for Shanxi Advanced Permanent Magnetic Materials and TechonologyShanxi Normal UniversityTaiyuan 030006China

Two-dimensional(2D)semiconductors with intrinsic ferromagnetism are highly desirable for potential applications in nextgeneration spintronic and optoelectronic ***,controllable synthesis of intrinsic 2D magnetic semiconductor on a substrate is still a challenging ***,large-area 2D non-layered rock salt(α-phase)MnSe nanosheets were grown on mica substrates,with the thickness changing from 54.2 to 0.9 nm(one unit cell),by chemical vapour *** X-ray diffraction,Raman spectroscopy,transmission electron microscopy,and X-ray photoelectron spectroscopy measurements confirmed that the resulting 2Dα-MnSe nanosheets were obtained as high-quality single *** magnetic hysteresis loops and synchrotron X-ray measurements directly indicated the anomalous magnetic properties inα-MnSe *** analysis of the reasons for magnetic property revealed that the low-temperature phase transition,small number of stacking differences in crystals,and surface weak oxidation in(111)-orientedα-MnSe were the main ***,α-MnSe nanosheets exhibited broadband photoresponse from 457 to 671 nm with an outstanding detectivity and responsivity *** study presents the detailed growth process of ultrathin 2D magnetic semiconductorα-MnSe,and its outstanding magnetic properties and broadband photodetection,which provide an excellent platform for magneto-optical and magneto-optoelectronic research.

关键词： two-dimensional material anomalous magnetism broadband photodetection α-phase MnSe non-layered crystal

Controlled synthesis of GeSe_(2) and GeSe nanostructures induced by TBAB

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Rare Metals 2023年第1期42卷 189-197页

作者： Huan Yang Yue Wu Li-Yan Hu Juan-Juan Wang Fang Wang Xiao-Hong Xu School of Chemistry and materials Science of Shanxi Normal University and Key Laboratory of magnetic Molecules and magnetic Information materials of Ministry of Education Taiyuan031000China Research Institute of materials Science of Shanxi Normal University and Collaborative Innovation center for Advanced Permanent magnetic materials and Technology of Ministry of Education Taiyuan031000China

Ge-based selenides have attracted extensive attention as promising candidates for future optoelectronic *** great progress has been achieved,the controlled synthesis of GeSe2and GeSe nanostructures and understanding the relative growth mechanisms of them are still ***,monodispersed GeSe_(2) nanoflowers with a diameter of~4μm and highly uniform GeSe nanoparticles with a lateral size of~100 nm are presented by using a colloidal synthetic *** is found that borane tert-butylamine complex(TBAB)plays an important role in determining the Ge-Se crystal phases due to its moderately ***,the coexistence of GeSe_(2) and GeSe phases can also be acquired by precisely controlling the amount of *** brief,this work provides both new insights of the phase control of Gebased selenides by liquid-phase method and a practical means of producing well-controlled germanium selenide nanostructures.

关键词： GeSe_(2) GeSe Borane tert-butylamine complex(TBAB) Liquid-phase method Bandgaps

Homogeneous and inhomogeneous magnetic oxide semiconductors

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Chinese Physics B 2019年第9期28卷 1-8页

作者： Xiao-Li Li Xiao-Hong Xu Key Laboratory of magnetic Molecules&magnetic Information materials of Ministry of Education and School of Chemistry and materials Science Shanxi Normal UniversityLinfen 041004China Research Institute of materials Science of Shanxi Normal University and Collaborative Innovation center for Shanxi Advanced Permanent magnetic materials and Technology Linfen 041004China

magnetic oxide semiconductors are significant spintronics *** this article, we review recent advances for homogeneous and inhomogeneous magnetic oxide *** the homogeneous magnetic oxide semiconductors,we focus on the various doping techniques including choosing different transition metals, codoping, non-magnetic doping,and even un-doping to realize homogeneous substitution and the clear magnetic *** the enhancement of the ferromagnetism is achieved by nanodot arrays engineering, which is accompanied by the tunable optical *** the inhomogeneous magnetic oxide semiconductors, we review some heterostructures and their magnetic and transport properties, especially magnetoresistance, which are dramatically modulated by electric field in the constructed *** the related mechanisms are discussed in ***, we provide an overview and possible potential applications of magnetic oxide semiconductors.

关键词： magnetic oxide semiconductors ferromagnetism magnetoresistance

Reversible control of magnetic and transport properties of NdNiO_(3-δ)epitaxial films

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Journal of Rare Earths 2021年第3期39卷 317-322,I0003页

作者： Huihui Ji Guowei Zhou Jun Zhang Xiaojiao Wang Xiaohong Xu Key Laboratory of magnetic Molecules and magnetic Information materials Ministry of EducationSchool of Chemistry and Materials ScienceShanxi Normal UniversityLinfen 041004China Research Institute of materials Science of Shanxi Normal University&Collaborative Innovation center for Shanxi Advanced Permanent magnetic materials and Technology Linfen 041004China

Rare-earth nickelates possess intrinsic charge order,orbital order,and electron-lattice coupling,which make them very interesting for applications in oxide-based electronic *** this study,we grew NdNiO_(3-δ)(NNO) films with oxygen pressures changing from 27 to 10^(-5) *** decreasing oxygen pressure,the antiferromagnetic state of the NNO film becomes a ferromagnetic state,and the resistance increases *** to combined X-ray absorption spectro scopy and X-ray linear dichroism measurements,the ratio of Ni^(2+)-ions increases with decreasing oxygen-pressure,and the preferred orbital occupation changes from x^(2)-y^(2) to 3 z^(2)-r^(2).In addition,using the ionic-liquid gating method to control the migration of oxygen vacancies,both the magnetic properties and resistance of NNO films can be modulated *** oxygen vacancy induces a valence in the Ni ions and the orbital occupation changes,which alters the magnetic properties and the electronic transport in these NNO *** study describes a novel tunable method for electronic devices that use NdNiO_(3-δ) films,and opens new doors for future improvements and functionalities.

关键词： NdNiO3 films Oxygen vacancy Valence state Orbital occupation Ionic liquid gating Rare earths