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Journal of Rare Earths 2004年第z1期22卷 79-83页

作者： Yu Ning Ji Jingwen College of Sciences Northeastern University Shenyang 110004 China College of SciencesNortheastern University Shenyang 110004 China

The expression of critical size of ferromagnetic microcrystal in an external magnetic field with an intensity of H is derived by means of comparing energies of domain structure *** ferromagnetic microcrystal here means an ferromagnetic single crystal with the size which is smaller than L0, and L0 is the critical value of the size of single-domain particles at the external magnetic field intensity H =***, the coercive strength H(Ls) relating to the size of microcrystal Ls is given and quantitatively evaluated with the material SmCo5 as an *** is thus concluded that if L0 ＞ Ls ＞ LC, the antimagnetization of microcrystal will be subjected to a multi-domain process just like the particles of a size greater than L0, only if Ls ＜ LC, the anti-magnetizaton will be carried on in accordance with the Stoner-Wohlforth mechanism( LC is the maximum size of microcrystal with MHcth ).It is suggested that the material RECo5 is available to make an advanced magnet with MHC = 2 K/Mc.

关键词： magnetization mechanism coercive force ferromagnetic microcrystal

Semi coercive Monotone Variational Problems on Reflexive Banach Spaces

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Journal of Mathematical Research and Exposition 1997年第2期17卷 190-192页

作者：唐春雷西南师范大学数学系

Using only chassical theorems of calculus of variations, we study semi coercive monotone variational problems on reflexive Banach spaces. We obtain the existence of solutions for semilinear equations on reflexive Ban... 详细信息

关键词： minimizing sequence minimum coercive lower semicontinuous convex function semilinear equation.

Electrical and optical modulation on ferroelectric properties of P(VDF-TrFE) thin film capacitors

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Journal of Materials Science & Technology 2019年第10期35卷 2194-2199页

作者： Xiaohan Li Biaohong Huang Weijin Hu Zhidong Zhang Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of Sciences(IMRCAS)Shenyang110016China School of Material Science and Engineering University of Science and Technology of China(USTC)Anhui230026China

Modulating the ferroelectric properties of P(VDF-TrFE) polymers both electrically and optically could open up new opportunities for their applications in non-volatile memories and sensors. Here by using the Nb:SrTiO3 semiconductor as electrode compared with metal Au electrode, we report on the modulation of ferroelectric properties of P(VDF-Tr FE) thin film capacitors both by electric field and UV light. A ferroelectric hysteresis loop shift together with the asymmetric switching behavior has been observed when using semiconducting electrode, which could be explained by the band alignment model based on interfacial charge screening. On the basis of band bending near the ferroelectric/semiconductor interface,we could further modulate the ferroelectric switching behaviors reversibly by UV light illumination. Our research provides a new route to engineer the ferroelectric properties of P(VDF-TrFE) polymer thin film capacitors, promising their applications in optoelectronic devices.

关键词： P(VDF-TrFE) Ferroelectric Semiconducting electrode coercive field Switching dynamics UV-light

Existence and Asymptotic Behavior of Ground State Solutions for Quasilinear Schr?dinger Equations with Unbounded Potential

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Chinese Annals of Mathematics,Series B 2023年第3期44卷 345-360页

作者： Yanfang XUE Xiaojing ZHONG Chunlei TANG School of Mathematics and Statistics Xinyang Normal University464000XinyangHenanChina School of History Culture and EthnologySouthwest UniversityChongqing400715China School of Mathematics and Statistics Southwest UniversityChongqing400715China

The authors study the existence of standing wave solutions for the quasilinear Schr?dinger equation with the critical exponent and singular *** applying the mountain pass theorem and the concentration compactness prin... 详细信息

关键词： Quasilinear Schrödinger equation Ground state Critical Hardy-Sobolev exponents coercive

Electroless deposition of Ni on template of halloysite and its magnetic property

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中国有色金属学会会刊：英文版 2004年第z1期14卷 152-156页

作者： FU Yu-bin ZHANG Li-de ZHENG Ji-yong Institute of Solid State Physics Chinese Academy of Sciences Hefei 230031 China Luoyang Ship Material Research Institute Luoyang 471039 China Institute of Solid State Physics Chinese Academy of Sciences Hefei 230031 China Luoyang Ship Material Research Institute Luoyang 471039 China

Halloysite template, a ceramic substrate, is of a hollow cylindric structure, on which the fine Pd nanoparticles are uniformly formed by the reduction of palldate chloride to initiate electroless deposition. The electroless deposition of Ni is catalyzed by the Pd particles, which results in a uniform layer of Ni-P alloy on halloysite. The alloy is of a nanocrystalline structure, of which the average diameter is about 6 nm. After being heat-treated at 400 ℃, it contains both Ni and Ni12P5 crystal, meanwhile, the Ni crystal gets larger with an average size of 51.9 *** content of phosphorous in the Ni layer has a great influence on crystal structure. The metallized halloysite has a higher inherent coercive force, and a much lower saturation magnetization in its as-plated state, while after heattreatment, the inherent coercive force decreases drastically. These magnetic properties have great relationship with the superparamagnetism of Ni nanocrystalline and the stress anisotropy in Ni layer.

关键词： halloysite template electroless deposition Ni nanocrystalline inherent coercive force

Presence of neodymium and gadolinium in cobalt ferrite lattice:Structural,magnetic and microwave features for electromagnetic wave absorbing

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Journal of Rare Earths 2020年第4期38卷 411-417页

作者： Alireza Nikzad Roghaieh Parvizi Department of Physics College of SciencesYasouj UniversityYasouj75914-353Iran

In this work,neodymium substituted gadolinium-cobalt ferrite nanoparticles were synthesized by hydrothermal *** significant role of doping both the Nd3+and Gd3+ions to cobalt ferrite in manipulating the cation distribution and further in influencing structural and magnetic properties was experimentally studied and *** influence of Nd3+substitution was investigated with step of 0.02-0.1 into the optimized Gd-Co *** crystal structure formation and crystallite size were explored by X-ray diffraction analysis in which the crystallite size and lattice constant decrease with increasing the Nd3+*** microstructural properties were studied by field emission scanning electron microscopy and atomic force microscopy *** obtained structural and morphological results reveal that the substitution of Nd3+with more than 0.06 into the Gd-Co ferrites will change the material be havior and *** saturation magnetization and coercivity values were measured using a vibration sample magnetometer at room *** microwave absorption experiments demonstrate that the reflection loss properties enhance with increasing substitution of Nd3+cations in Gd-Co ferrite spinel *** research reports that the as-prepared Nd3+substituted Gd-Co ferrite compound stands as promising candidate for absorbing electromagnetic wave with a wider absorbing bandwidth of X-band.

关键词： Gd-Co nanoferrite coercive field Microwave absorption Rare earths

Micromagnetic simulations on demagnetization processes in anisotropic Nd_2Fe_(14)B magnets

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Journal of Rare Earths 2019年第6期37卷 628-632页

作者： Lei Li Shengzhi Dong Rui Han Kuikui Song Dong Li Minggang Zhu Wei Li Wei Sun Division of Functional Materials Research Central Iron and Steel Research Institute National Engineering Research Center for Magnetic Materials

Individual grains with diverse dimensional parameters were introduced to investigate the magnetization reversals in anisotropic Nd2 Fe_(14)B magnets. The micromagnetic simulations were carried out via Object Oriented MicroMagnetic Framework(OOMMF). With the same bottom area and height, analysis results show that the coercive fields for different bottom shapes are of similar values. Designed as a cubic grain,the coercive field presents descending tendency as grain volume ascends. Under constant grain volume,with aspect ratio increasing, the coercive field decreases in the beginning and increases soon. Based on the demagnetization field vector, the effects of bottom shape, grain volume and aspect ratio on the coercive field can be explained. The nucleation point is chosen to discuss. Its synthetic field and reversal field are calculated by parallelogram law and inverse external field equation, respectively. The synthetic field equal to the reversal field is defined as critical field, which always shows the same tendency as the coercive field for all cases of this study. It can be concluded that critical field is qualified to be a reference index to measure the magnitude of coercive field.

关键词： Micromagnetic simulation Demagnetization field coercive field Synthetic field Critical field Rare earths

Magnetic properties and crystallization behavior of nanocrystalline FeSiBPCuAl alloys

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Science China(Technological Sciences) 2010年第6期53卷 1590-1593页

作者： DONG BangShao1,ZHOU ShaoXiong1,HU MingJun2,KONG FanLi2,CHEN WenZhi1 & SHEN BaoLong2 1 Central Iron & Steel Research Institute,Advanced Technology & Materials Co.,Ltd.,Beijing 100081,China 2 Magnetic Materials and Advanced Devices Departments,Ningbo Institute of Material Technology & Engineering,Chinese Academy of Sciences,Ningbo 315201,China 1. Central Iron & Steel Research Institute Advanced Technology & Materials Co. Ltd. Beijing 100081 China2. Magnetic Materials and Advanced Devices Departments Ningbo Institute of Material Technology & Engineering Chinese Academy of Sciences Ningbo 315201 China

Magnetic properties and crystallization behavior of nanocrystalline (Fe83.3Si4B8P4Cu0.7)100-xAlx (x=0-1.5 at%) alloys were investigated in this *** results show that coercive force decreases and saturation magnetization slightly decreases with the increase of Al content,but the glass forming ability has been improved at the same *** behavior including the evolution of microstructure has also been *** growth of α-Fe precipitated from the matrix is quick when it is annealed by conventional method and the mean size of α-Fe grains increases from below 2-3 nm to 18-29 *** (Fe83.3Si4B8P4Cu0.7)99Al1 alloy with coercive force of 8.9 A/m and saturation magnetization of 187 emu/g is probably a promising candidate in the field of soft magnetic materials.

关键词： nanocrystalline alloy glass forming ability saturation magnetization coercive force

FINITE DIMENSION OF GLOBAL ATTRACTORS FOR DISSIPATIVE EQUATIONS GOVERNING MODULATED WAVE

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Applied Mathematics(A Journal of Chinese Universities) 2003年第4期18卷 421-430页

作者： YangLin DaiZhengde Dept.ofAppl.Math. ShanghaiJiaotongUniv.Shanghai200240China Dept.ofMath. YunnanUniv.Kunming650091China

The finite dimension of the global attractors for the systems of the perturbed and unperturbed dissipative Hamiltonian amplitude equations governing modulated wave are *** interesting result is also obtained that the ... 详细信息

关键词： Hausdorff and fractal dimension Frechet differential exterior product coercive

On the Uniqueness Theorem of Time-Harmonic Electromagnetic Fields

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Journal of Electromagnetic Analysis and Applications 2011年第1期3卷 13-21页

作者： Yongfeng Gui Pei Li 不详

The uniqueness theorem of time-harmonic electromagnetic fields, which is the theoretical basis of boundary value problem (BVP) of electromagnetic fields, is reviewed. So far there are many versions of the statements and proofs on the theorem. However, there exist some limitations and lack of strictness in these versions, for instance, the discussion of the uniqueness of solution without considering the existence of solution and the lack of strictness in the case of loss-less medium. In contrast with the traditional statements and proofs, this paper introduces some important conclusions on operator equation from modern theory of partial differential equation (PDE) and attempts to solve the problems on the existence and uniqueness of the solution to operator equation which is derived from Maxwell’s equations of time-harmonic electromagnetic fields. This method provides a novel and rigorous approach to discuss and solve the existence and uniqueness of the solution to time- harmonic fields in the new mathematical framework. Some important conclusions are presented.

关键词： Time-Harmonic Fields The Existence and Uniqueness of Solution the Case of Lossless Medium Operator Equation Variational Principles Weak Solution coercive Condition