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891.
M. Y. Koledintseva 《Opto-Electronics Review》2006,14(3):253-262
Coupling matrix and coupling coefficient concepts are applied to the interaction of an incident plane wave with a regular
array of small magnetized or polarized ellipsoids, placed in a homogeneous surrounding medium. In general case, the angle
of incidence and polarization of the plane wave upon an array of ellipsoids can be arbitrary. In this model, it is assumed
that all the ellipsoids are the same, and the direction of their magnetization is also the same. The direction of magnetization
is arbitrary with respect to the direction of the propagation of the incident wave and to the boundary plane between the first
medium, where the incident wave comes from, and the array material under study. Any magnetized or polarized ellipsoid is represented
as a system of three orthogonal elementary magnetic radiators (EMR) and/or three orthogonal elementary electric radiators
(EER). Mutual interactions of individual radiators in the array through the incident plane wave and corresponding scattered
electromagnetic fields are taken into account. The electrodynamic characteristics — reflection from the surface of the semi-infinite
array (in particular, containing uniaxial hexagonal ferrite resonators), transmission through the array, and absorption are
analyzed. 相似文献
892.
R. Sato Turtelli Giap V. Duong W. Nunes R. Grssinger M. Knobel 《Journal of magnetism and magnetic materials》2008,320(14):e339-e342
Nanocrystalline CoFe2O4 with an average grain size of about 40 nm was successfully prepared by a modified citrate-gel method. At temperatures of 3 and 300 K, the measured coercive fields are 0.43 and 0.07 T and the magnetizations at 7 T are 89 and 83 emu/g, respectively. At room temperature, the longitudinal and transversal magnetostriction values are −130 and 70 ppm, respectively. The contribution of a disordered magnetic phase was detected by the occurrence of a peak in the ac-susceptibilities curves at around 250 K. The temperature dependence of the field-cooled and zero field-cooled low-field magnetization showed a larger irreversibility below this temperature. This disordered phase behaves like a spin-glass, which is coexisting with the ferrimagnetically ordered main phase 相似文献
893.
Mai Lu Zheng Yang Fu-Lin Wei 《International Journal of Infrared and Millimeter Waves》1998,19(7):1027-1036
The distribution of the magnetization in ferrite devices is nonuniform due to their nonellipsoidal shapes. In this paper, the local-demagnetization tensor of magnetized nonellipsoidal ferrite is proposed and calculated. By analysing the distribution of the tensor elements, the distribution of the demagnetizing field can be obtained. The method is simple yet accurate. It can be used to calculate the nonuniform magnetizing distribution in ferrite devices as well as optimize the ferrite devices in the CAD of MMIC. 相似文献
894.
C. Estournès C. D’Orléans J.-L. Rehspringer E. Manova B. Kunev D. Paneva I. Mitov L. Petrov M. Kurmoo 《Hyperfine Interactions》2005,165(1-4):61-67
Magnetic nanoparticles of cobalt ferrites Co
x
Fe3−x
O4 (x = 1 or 2) have been obtained either by mechanical milling or thermal treatment of pre-prepared layered double hydroxide carbonate
x-LDH–CO3. Mechanical milling of the 1-LDH–CO3 leads to the large-scale preparation of nearly spherical nanoparticles of CoFe2O4, the size of which (5 to 20 nm) is controlled by the treatment time. Core-shell structure with surface spin-canting has been
considered for the nanoparticles formed to explain the observed hysteresis loop shift (from ZFC–FC) in the magnetic properties.
Annealing treatment of the 2-LDH–CO3 below 673 K results in the formation of nearly spherical pure Co2FeO4 nanoparticles. At 673 K and above, the LDH decomposition leads to the formation of a mixture of both spinels phases Co2FeO4 and CoFe2O4, the amount of the latter increases with annealing temperature. Unusually high magnetic hardness characterized by a 22 kOe
coercive field at 1.8 K has been observed, which reflects the high intrinsic anisotropy for Co2FeO4. 相似文献
895.
Shul'ga N. A. Levchenko V. V. Ratushnyak T. V. 《International Applied Mechanics》2003,39(11):1305-1309
Surface magnetoelastic Love waves in a regularly stratified medium with ferrite and dielectric layers are studied based on the Hamilton formalism and numerical procedures. The dispersion relations are analyzed for particular structures 相似文献
896.
《Current Applied Physics》2020,20(4):589-592
Spinel lithium ferrite LiFe5O8 (LFO) has attracted robust research interests due to their potential applications in isolators, circulators, and phase shifters. In this work, a series of LFO thin film with various thickness were fabricated on SrTiO3 (STO) single-crystalline substrates by pulsed laser deposition technology. We systematically investigated the influences of the thickness of LFO thin film on the crystal structure and magnetic properties. The in-plane lattice parameter a and in-plane lattice parameter c were modulated by controlling the thickness of LFO thin film, which was confirmed using reciprocal space mappings (RSMs) technology. Furthermore, the microwave magnetism of LFO thin film with various thickness were studied systematically by ferromagnetic resonance (FMR) measurement. Moreover, with increasing the thickness of LFO thin film from 50 to 180 nm, the difference of the ferromagnetic resonance field between easy- and hard-magnetization axis can be enhanced and reach to 330 Oe. These results illustrate that dynamic magnetic properties can be controlled by tuning the thickness of LFO thin film. Our work provides an effective method to tailor the lattice parameter and modify the magnetic properties of the LFO thin film and contributes to further design high-frequency functional device. 相似文献
897.
雒向东 《新疆大学学报(理工版)》2002,19(2):183-185
推证了媒质无损耗的条件,并以此条件为依据对恒磁场中铁氧体材料的电磁性质进行了理论分析。 相似文献
898.
Bronislav E.Kashevsky Vladimir E.Agabekov Sergei B.Kashevsky Katsiaryna A.Kekalo Elena Yu.Manina Igor V.Prokhorov Vladimir S.Ulashchik 《中国颗粒学报》2008,6(5)
High-coercive cobalt ferrite nanoparticles were synthesized and studied for magnetic hyperthermia by direct injection of their suspension into a tumor and application of a strong audio-frequency magnetic field for heating.Physical (dynamic magnetic hysteresis and heat generation in both liquid and solid dispersions),biological (toxicity and penetration of particles in therapeutic quantities into mouse tumor tissue) as well as other properties of the particles were studied.A model was developed to describe the magnetodynamics in suspensions of magnetic nanoclusters with an account for both Brownian and regular rotations,to provide understanding of observed phenomena.The experimental and theoretical techniques developed have formed a basis for controllable synthesis of the magnetic nanoparticles for low-frequency heat generation in medical and other applications. 相似文献
899.
Evolution of phase purity and texture on annealing of BiFeO3 thin film prepared by sol-gel technique
Priyadarshini Dash B. N. Dash Haripriya Rath Chandana Rath N. C. Mishra 《Indian Journal of Physics》2009,83(4):485-491
We report preparation of phase pure BiFeO3 thin films on glass, ITO and Si(100) substrates through chemical route using spin coating technique. Sol-gel process was
adopted to prepare the films using bismuth nitrate and iron nitrate as precursors. X-Ray diffraction and Raman spectroscopy
studies revealed amorphous nature of the as deposited films. Rhombohedral crystalline phase of BiFeO3 evolved on annealing the films at 500°C, but with Bi2Fe4O9 and Bi24Fe2O39 as impurity phases. Increasing the annealing temperature to 550°C caused a drastic reduction of the impurity phases and at
600°C, the films were phase-pure BiFeO3. Micro Raman spectra showed features consistent with the reported characteristic peaks of BiFeO3 crystalline phase for films annealed at 500 and 550°C. Crystallite size obtained from X-ray diffraction line width analysis
are within 30 to 40 nm. Atomic force microscopy (AFM) however showed grain size of ∼192 nm, indicating polycrystalline nature
of the grains.
相似文献
900.
Scattering characteristics of conducting cylinder coated with nonuniform magnetized ferrite
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An analytical technique, referred to as the scattering matrix method (SMM), is developed to analyse the scattering of a planar wave from a conductolution for the nonuniform fering cylinder coated with nonuniform magnetized ferrite. The SMM srite coating can be reduced to the expressions for the scattering and penetrated coefficients in four particular cases: nonuniform magnetized ferrite cylinder, uniform magnetized ferrite-coated conducting cylinder, uniform ferrite cylinder as well as homogeneous dielectric-coated conducting cylinder. The resonant condition for the nonuniform ferrite coating is obtained. The distinctive differences in scattering between the nonuniform ferrite coating and the nonuniform dielectric coating are demonstrated. The effects of applied magnetic fields and wave frequencies on the scattering characteristics for two types of the linear profiles are revealed. 相似文献