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1.
The magnetic properties of polycrystalline Fe3−xVxAl alloys with x≤0.8 having atomically disordered structure of the A2 type were investigated by magnetostatic and Mossbauer
methods. It was ascertained that the magnetic moment and the Curie temperature decrease approximately linearly with increasing
x. Above the Curie temperature investigated alloys do not obey the Curie-Weiss law. Marked nonlinear variations of magnetic
susceptibility with magnetic field intensity indicate the existence of magnetic clusters. Mossbauer investigations also confirmed
the existence of magnetic clusters with short relaxation time.
This work was partially supported by the Institute of Physics, PAN, in problem CPBP No 01. 04. 0. II. 2. 6. 相似文献
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Sea nodules were extensively studied over a wide range of temperature ranging from 77K to 1175K using Mossbauer effect and
ESR. The Mossbauer studies of the nodules at 77K and room temperature show a quadrupole doublet whereas at higher temperatures
magnetic spectra were obtained starting at around 875K which ultimately gives a hyperfine field of around 390 KOe at 1175
K. The Mossbauer spectra recorded at 30K did not show any significant change in the room temperature spectra. The analysis
of the spectra upto 775K showed two positions of FeR+, vie., octahedral and tetrahedral which were varified by ESR of the diluted samples. 相似文献
4.
D. R. S. Somayajulu Narendra Patel Mukesh Chawda Mitesh Sarkar K. C. Sebastian 《Hyperfine Interactions》2005,160(1-4):241-246
Hyperfine interaction techniques like Mossbauer spectroscopy are very sensitive tools to study the local probe interactions
in dilute magnetic semiconductors. We report here a Mossbauer study on the concentration dependence in Fe0.008Ge1 − x
Te
x
for x = 0, 0.008, 0.016, 0.03 and 0.05. At room temperature magnetic interactions were observed for all concentrations of Te and
the population of magnetic site was found to increase gradually with the Te concentration. A constant magnetic hyperfine field
of 136 KOe was found. A quadrupole doublet due to the FeTe2 compound phase was also seen. 相似文献
5.
The effect of heat treatment on the Fe2+/Fe3+ ratio in some alkali phosphate glasses containing antimony and iron oxides has been investigated. Differential thermal analysis, Mossbauer spectroscopy, magnetic susceptibility and density measurements as well as the molar volume calculations were used in this study. The obtained data indicate that all glasses show approximately unchangeable stability. It is found, from the area under the Mossbauer absorption spectra that ferrous transformed gradually to ferric ions and the transformation rate constant was found to be 48 min−1. The elapsed time was found to be 160 min. This transformation represents a first-order solid state reaction. The molar magnetic susceptibility measurements confirm the above results. 相似文献
6.
Electromagnetic wave absorbing properties and hyperfine interactions of Fe–Cu–Nb–Si–B nanocomposites
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The Fe–Cu–Nb–Si–B alloy nanocomposite containing two ferromagnetic phases(amorphous phase and nanophase phase) is obtained by properly annealing the as-prepared alloys. High resolution transmission electron microscopy(HRTEM) images show the coexistence of these two phases. It is found that Fe–Si nanograins are surrounded by the retained amorphous ferromagnetic phase. M¨ossbauer spectroscopy measurements show that the nanophase is the D03-type Fe–Si phase, which is employed to find the atomic fractions of resonant57 Fe atoms in these two phases. The microwave permittivity and permeability spectra of Fe–Cu–Nb–Si–B nanocomposite are measured in the frequency range of 0.5 GHz–10 GHz. Large relative microwave permeability values are obtained. The results show that the absorber containing the nanocomposite flakes with a volume fraction of 28.59% exhibits good microwave absorption properties. The reflection loss of the absorber is less than-10 dB in a frequency band of 1.93 GHz–3.20 GHz. 相似文献
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The morphology, Mossbauer spectra and magnetic properties of ultrafine particles (10nm) as a core of magnetic carriers (MC)
and dextran-ferrite microspheres are studied. The result suggested the presence of two ferrimagnetic at 300K ferric phases,
inheriting their valency, crystallographic state and magnetic properties at creating iron-dextran complexes. 相似文献
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Sh. M. Aliev I. K. Kamilov M. M. Guseinov S. O. Shakhshaev M. Sh. Aliev 《Russian Physics Journal》2005,48(2):170-174
Methods of determining the degree of magnetic structure perfection and the constant of uniaxial magnetic anisotropy of microparticles in constant powder magnets based on Mossbauer spectroscopy are suggested and tested experimentally.__________Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 59–62, February, 2005. 相似文献
11.
SteenMφrup 《物理学进展》2011,6(3):257-275
在穆斯堡尔谱学的实验结果基础上讨论了微晶的磁性。微晶的尺寸小于10um时,穆斯堡尔谱将受到磁化方向起伏,即超顺磁弛豫与集体磁激发的影响。这些效应可用来确定颗粒体积与磁各向异性常数二者之积。测量铁磁、亚铁磁颗粒穆斯堡尔谱随外磁场的变化可以确定颗粒的体积。当铁、钴、镍以及Fe_3O_4颗粒表面化学吸附不同的分子时,微晶的磁晶各向异性常数将随之改变。细颗粒的穆斯堡尔谱亦给出了表面层原子磁性的信息。α-Fe颗粒表面层原子的超精细场大于块状样品的值。FeCo合金颗粒的表面是富铁层。α-Fe_2O_3的Morin转变温度与Fe_3O_4的Verwey温度均发现随颗粒尺寸减小而降低。α-FeOOH微晶密堆积体的研究表明,这些微晶间的磁耦合显著地影响穆斯堡尔谱。 相似文献
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Mossbauer spectroscopy has recently been applied to study the new high Tc superconducting compounds RBa2Cu3Oz, using isotopes of rare earths mainly155Gd and151Eu, and57Fe, with different amounts of Fe ions replacing Cu. It was shown that magnetic moments on the rare earth site do not interfere
with superconductivity. Fe at low concentrations (<1%) was found to replace Cu mainly in the Cu(1) site, and the Mossbauer
spectra reveal different quadrupole doublets-fol lowing the different oxygen coordination around the Fe ion. The change of
the relative intensities of the different doublets with z can easily be followed. For higher iron concentrations, it seems
that increasing amounts of iron replace Cu in the Cu(2) site. For z<6.5, the iron reflects the magnetic ordering of Cu in
this site, and the ordering temperature as function of z can be obtained. The agreement between neutron diffraction and Mossbauer
measurements prove that Fe is a good probe for the magnetic behaviour of the Cu(2) ions. At low temperatures, Fe Mossbauer
spectra of Fe in the Cu(1) site are also magnetically broadened, for all z.
Superconducting-magnetic phase diagrams are also obtained in Y1−x Prx Ba2 Cu3Oz as function of x and z. For z=7.1, TN changes sharply with x. TN=300, 230 and 35 K for x=0.8, 0.6 and 0.4 respectively, whereas for z=6.1 TN changes very little with x.
Mossbauer measurements performed on 5 at %57Fe doped in CalaBaCu3Oz show that most of the la occupy the Ba site. For z=7 about half the iron in the Cu(2) sites are magnetically ordered, with
Heff=520 kOe and TN=400 K, even though the sample is superconducting with Tc=35 K. The possibility of coexistence between superconductivity and magnetic order in these systems will be discussed. 相似文献
14.
The magnetic properties of ultrathin films are determined first of all by their structure. The experimental technique giving
simultaneously information about the structure and the magnetic behaviour of the film would be optimum. To follow this idea
the information about the film structure, obtained from Mossbauer spectra, are discussed. 相似文献
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P. N. Tandon V. S. Patil A. K. Grover R. G. Pillay H. G. Devare 《Hyperfine Interactions》1983,16(1-4):709-712
A new class of magnetic system RuxFeySi, has been identified in which the hyperfine field at Fe, as sensed by57Fe Mossbauer effect, is seen to evolve at a characteristic temperature far below the bulk magnetic ordering temperatures. 相似文献
17.
The as quenched amorphous ribbons are in a metastable condition and need a thermal treatment to relax internal stresses and/or
to induce magnetic anisotropy. The evaluation of the results of various annealing treatments of the alloy Metglas 2826 was
performed by magnetic measurements and Mossbauer spectroscopy, for the characterization of structural relaxation, easy magnetization
axis changes and transition to crystalline order. Heat treatments considered include conventional (batch), laser and magnetic
annealing (in transversal field). 相似文献
18.
A Fe−Si (6at%) single crystal with a (110) surface was studied by a Mossbauer spectroscopy as a function of the angle between
a crystal axis <100> and the magnetization direction <hk1>. The difference spectra reveal Si atoms give rise to a magnetic
dipolar field, of which magnitude varies with the angle as expected for the Si atom in the 2nd neighbor site. The dipolar
field was found to take place at the main lines of Mossbauer spectrum to reveal the Si atom in the 2nd neighbor site never
reduces the hyperfine field at the Fe probe nuclei, which supports the earlier proposals by Cranshaw. 相似文献
19.
H.-D. Pfannes D. S. Vieira Junior R. Paniago J. H. Dias Filho 《Hyperfine Interactions》2005,165(1-4):247-252
The formation of local moments and the effect of charge carrriers in dilute magnetic semiconductors can be well understood using local probe techniques like Mossbauer Spectroscopy. We report here on Mossbauer studies in the systems Fe0.008Ge1 ? x D x (D = As, Bi), Fe0.008Ge1 ? x In x , and Fe0.008Ge1 ? x Sn x . At room temperature magnetic interactions were observed for donor (D) impurities at the Fe site in the Fe0.008Ge system. No such magnetic ordering was observed for acceptor (In) or neutral (Sn) impurities. 相似文献
20.
N.V. Kazak N.B. Ivanova O.A BayukovS.G Ovchinnikov A.D. Vasiliev V.V. RudenkoJ. Bartolomé A. ArauzoYu.V. Knyazev 《Journal of magnetism and magnetic materials》2011,323(5):521-527
The crystal structure, cation distribution and exchange interactions in the Co2.25Fe0.75O2BO3 ludwigite have been explored through X-ray diffraction, electrical resistivity, ac-susceptibility and Mossbauer effect measurements. The crystal data have shown that iron atoms occupy the most symmetric crystallographic sites Fe4 and Fe2. The complex magnetic behavior with two magnetic transitions near 70 and 115 K at low temperatures was found. The Mossbauer data have displayed the trivalent iron states only. The values of superexchange energies have been estimated for Co3O2BO3 and Co2.25Fe0.75O2BO3 yielding a significant role of frustrations in the ludwigite magnetic system. Variable range Mott hopping conductivity law was proved to be valid in the wide temperature region, pointing out a localized character of charge carriers rather than collective. 相似文献