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1.
The variations of induced magnetic anisotropy with annealing and measuring temperatures in metallic glasses (Fe1 − xCox)78Si10B12 have been measured. It was found that Ku (T) was proportional to Mns (T) for T below 200°C, and the index n varied with the cobalt content x and annealing conditions, not being smaller than 3. To the predictions of the existing pair-ordering and single-ion theories, the above results are anomalous. By considering the distributions of exchange integrals and activation energies in metallic glasses, this anomalous behaviour could be explained properly. 相似文献
2.
B. W. Wang Z. D. Zhang S. L. Tang X. M. Jin X. G. Zhao 《Journal of magnetism and magnetic materials》1997,170(3)
Structure, Curie temperature and magnetostriction of RFex (1.6 x 2.0) and R(Fe1−yTiy)1.8 (y 0.2) alloys (R=Dy0.65Tb0.25Pr0.1) have been investigated using optical microscopy, X-ray diffraction, AC initial susceptibility and standard strain gauge techniques. The homogenized RFex alloys are found to be essentially single phase in the range of 1.8 x 1.85. The second phase is a rare-earth-rich phase when x 1.8, and (Dy, Tb, Pr)Fe3 phase when x 1.85. X-ray diffraction indicates that the R(Fe1−yTiy)1.8 alloys contain a small amount of Fe2Ti phase when y 0.05, which increases with the increment of Ti content. The Curie temperature of R(Fe1−yTiy)1.8 alloys slightly enhances with increasing Ti concentration when y 0.05, then remains almost unchanged in the range of 0.05 y 0.20. The magnetostriction of RFex alloys is improved when x 1.80 and reduced by increasing Fe content when x 1.85. The magnetostriction of R(Fe1−yTiy)1.8 alloys is lowered by increasing Ti content. 相似文献
3.
A large positive magnetoresistance (MR) has been found in micro-sized Fex–C1−x composites. At a magnetic field of 5 T, the Fe0.2–C0.8 composite has the largest MR, 53.8% and 190% at room temperature and at 5 K, respectively. The magnetic field dependence of the MR can be described approximately as MR∝Bn, and the value of exponent n is determined by the Fe weight concentration and temperature, ranging from 1/4 to 6/4. It appears that Fex–C1−x has a linear field dependence of the positive MR at different temperatures. The possible mechanism for the positive MR is discussed. 相似文献
4.
Serial single-phase Gd2(Fe1−x−yCoyTix)17 compounds have been synthesized. These compounds have a crystal structure belonging to rhombohedral lattice with
space group. The lattice parameters of compounds decrease with cobalt content and increase with titanium content, respectively. The saturation magnetization decreases with increasing cobalt and titanium contents. The anisotropy fields increase to maximum then decrease with cobalt concentration. The magnetocrystalline anisotropy constants increase with cobalt content from negative to positive maximum and then decrease with Co concentration. The saturation moment of the compounds decreases linearly with cobalt concentration and decreases nonlinearly with titanium concentration. 相似文献
5.
Y. Nishihara M. Tokumoto Y. Yamaguchi G. Kido 《Journal of magnetism and magnetic materials》1987,70(1-3):173-174
The cubic Laves phase compound Ce(Fe0.95Al0.05)2 exhibits a first order magnetic phase transition from antiferromagnetic to ferromagnetic state at ≈ 100 K with increasing temperature. This note gives the results of the Mössbauer effect of 57Fe and the magnetic phase diagram in the external field vs. temperature plane. 相似文献
6.
A. M. Balagurov E. V. Raspopina V. V. Sikolenko I. S. Lyubutin A. S. Stepin A. V. Gribanov G. Andr F. Boure H. M. Duh 《Journal of magnetism and magnetic materials》2000,210(1-3)
The neutron diffraction and magnetic susceptibility studies have shown that the magnetic structure of UPd2Ge2 changes dramatically even under very low iron doping. Though the general magnetic structure of pure UPd2Ge2 and of 1%Fe-doped samples is the same, the temperature intervals of existence of different magnetic phases are different. The values of transition temperatures, where (i) the ‘square’ modulated longitudinal spin-density wave (LSDW) structure with the propagation vector k=(0; 0;
) starts to transform into the sinusoidal modulated LSDW structure and (ii) the commensurate phase transforms into incommensurate one, shift under the 1%Fe doping to the higher temperatures (from 50 to 65 K and from 80 to 90 K, respectively). In the pure and 1%Fe-doped UPd2Ge2, the magnetic transition from the commensurate to incommensurate phase is accompanied by the drastic decrease of the propagation vector kz. In the 2%Fe-doped sample, besides the Néel point of TN=135 K, we have found two additional characteristic temperatures of 65 and 93 K. Below 65 K, the material has a simple antiferromagnetic (AF) structure with the propagation vector k=(0; 0; 1) and, at 65 K<T<TN, the magnetic structure is LSDW with sinusoidal modulation. Over almost the total region 65 K<T<TN, the LSDW magnetic structure is incommensurate. Only at about 93 K, the propagation vector passes the commensurate value of
, whereas
at 65<T<93 K and
at 93 K<T<TN. We have found that the magnetic susceptibility and the uranium magnetic moment are sensitive to the
transition. With increasing iron concentration to x0.15, the simple AF structure with k=(0; 0; 1) develops over all temperature region up to the Néel point. Below TN, the uranium magnetic moments are always parallel to the tetragonal c-axis. 相似文献
7.
V. L. Mathe K. K. Patankar R. N. Patil C. D. Lokhande 《Journal of magnetism and magnetic materials》2004,270(3):380-388
Single-phase polycrystalline samples of Bi1−xNdxFeO3 were prepared by standard solid state reaction method. X-ray diffraction (XRD) patterns of the powder samples were recorded and analyzed for the confirmation of crystal structure lattice parameters. Further, these samples were characterized by IR technique to identify and understand the aspect of bonding in the present samples. The dielectric measurements were carried out on the samples as a function of frequency in the range 100 Hz to 1 MHz at room temperature and also as a function of temperature in the range 300–750 K at certain fixed frequencies. The DC and AC electrical resistivity studies were carried out in order to understand conduction mechanism in the samples. 相似文献
8.
V.R. Shah G. Markandeyulu K.V.S. Rama Rao M.Q. Huang K. Sirisha M.E. McHenry 《Journal of magnetism and magnetic materials》1998,190(3):1579
A novel class of Co-substituted 3 : 29 materials, Pr3(Fe1−xCox)27.5Ti1.5 (x=0, 0.1, 0.2, 0.3) have been synthesized. Rietveld analysis of X-ray powder diffraction patterns for the x=0, 0.1 and 0.2 compositions showed that nearly all of the compounds are formed in monoclinic symmetry, with A2/m space group with traces of α-Fe, whereas, in x=0.3, additional traces of a (Co/Fe)–Ti (1 : 12) phase are also seen. The saturation magnetization increases with Co concentration both at 5 and 300 K and is explained on the basis of a rigid band model. A magnetic transition is observed for x=0.1 near 240 K. A large increase in Curie temperature, of about 180 K for x=0.1 and about 110 K for the other concentrations, is discussed on the basis of the strengthening of TM–TM exchange by the preferential occupation of Co in some of the Fe sites originally participating in antiferromagnetic bonds. 相似文献
9.
10.
G.F. Wang L. Song F.A. Li Z.Q. Ou O. Tegus E. Brück K.H.J. Buschow 《Journal of magnetism and magnetic materials》2009,321(21):3548-3552
The effects of substitution of Co for Fe on the magnetic and magnetocaloric properties of La0.8Ce0.2Fe11.4−xCoxSi1.6 (0, 0.2, 0.4, 0.6, 0.8 and 1.0) compounds have been investigated. X-ray diffraction shows that all compounds crystallize in the NaZn13-type structure. Magnetic measurements show that the Curie temperature (TC) can be tuned between 184 and 294 K by changing the Co content from 0 to 1. A field-induced methamagnetic transition occurs in samples with x=0, 0.2 and 0.4. The magnetic entropy changes of the compounds have been determined from the isothermal magnetization measurements by using the Maxwell relation. 相似文献
11.
Darshan C. Kundaliya Reeta Vij D. G. Kuberkar R. G. Kulkarni 《Physica C: Superconductivity and its Applications》2000,340(4):317-322
The structural and superconducting properties of single-phase Fe-substituted La2.5Nd0.5CaBa3(Cu1−xFex)7Oz (LNCBCuFe) with 0.0x0.06 compounds having triple-perovskite structure are investigated using X-ray diffraction, a.c. susceptibility, d.c. magnetization, oxygen content and Mössbauer effect measurements. Mössbauer spectral analysis of x=0.03 sample displays unusual Fe-dopant site occupancies and the Cu(2) plane to Cu(1) chain site ratio in the LNCBCuFe are quite different from those of the usual Fe-doped YBa2Cu3O7−δ. Specifically, we observe substantial occupation of a new chain-associated quasi-octahedral site, E, at 300 K which transforms into the well-known distorted tetrahedron chain site, A, on lowering the temperature to 78 K. The observed reduction of Tc with increasing x in LNCBCuFe supports the view that the hole filling mechanism contributes predominantly to the suppression of superconductivity by Fe. 相似文献
12.
Structure and magnetic properties of the Zr1−xMnxCo2+δ alloys were studied for 0 x <0.7, δ=0, 0.45. The cubic C15 Laves phase structure shows Mn solubility up to x≈0.4. The other Laves phase with the hexagonal C36 structure found for x0.5 apparently has a small region of Mn solubility in the vicinity of Zr0.4Mn0.6Co2. Though the parent Mn-free compounds are known to be paramagnetic, the Mn-substituted alloys show ferromagnetic behavior with the Curie temperatures up to 625 K and the room-temperature saturation magnetization of about 100 emu/g. The onset of ferromagnetism with the Mn substitution for Zr may be caused by polarization of itinerant 3d electrons, like it was earlier supposed for the off-stoichiometric ZrCo2+δ. The universal composition dependencies of the intrinsic magnetic properties for different δ can be obtained, if plotted against the amount of zirconium atoms missing in its sublattice. The room-temperature anisotropy with the noticeable anisotropy field of 24 kOe and the 1 1 0 easy magnetization direction laying in a basal plane was found in the hexagonal Zr0.5Mn0.5Co2. 相似文献
13.
Experimental evidence shows that in the magnetoresistive manganite Ca1−xYxMnO3, ferromagnetic (FM) polarons arises in an antiferromagnetic (AF) background, as a result of the doping with yttrium. This hypothesis is supported in this work by classical Monte Carlo calculations performed on a model where FM double exchange and AF superexchange compete. 相似文献
14.
Large magnetic entropy change and magnetic properties in La (Fel-xMnx)ll.TSil.3Hy compounds 下载免费PDF全文
Magnetic properties and magnetic entropy change in La(Fe_{1-x}Mn_x)_{11.7}Si_{1.3}H_y compounds have been investigated. A significant increase of the Curie temperature T_C and a small increase of the saturation magnetizations μ_S have been observed after the introduction of interstitial H, which caused a slight volume expansion. The first-order field-induced itinerant-electron metamagnetic (IEM) transition remains and brings about a large magnetic entropy change around room temperatures for the compounds. The maximal magnetic entropy change is about 23.4, 17.7 and 15.9J/kg·K under a magnetic field change from 0 to 5T for x=0.01, 0.02 and 0.03, respectively. Therefore, the compounds appear to be potential candidates for magnetic refrigerants around room temperatures. 相似文献
15.
M. Oyasato K. Ichinose K. Fujiwara A. Tsujimura 《Journal of magnetism and magnetic materials》1987,70(1-3):233-235
The spin echo spectra of 89Y hyperfine fields in Y(Fe1−xTx)3 with low concentration x consist of two main lines and of satellite lines caused by the replacement of the Fe atoms by the T atoms. Values of the magnetic moments of the T atoms are estimated by observing the satellite lines. 相似文献
16.
Typical weak itinerant ferromagnetism has been found in Sc(Co1−xAlx)2, which a magnetism and higher Curie temperatures. Magnetic for X = 0.10. Lu(Co1−yAly)2 also shows ferromagnetism with much larger moments anad higher Curie temperatures. Magnetic and nonmagnetic Co atoms coexist in 0.06 < y < 0.12. 相似文献
17.
本文采用高温有机溶剂法制备了(Fe1-xCox)3BO5纳米棒, 通过控制反应物中乙酰丙酮钴的含量合成了不同Co含量的(Fe1-xCox)3BO5. 利用高分辨透射电子显微镜(HRTEM)、超导量子干涉磁强计(SQUID)对其形貌和磁性能进行了表征. 高分辨透射电子显微镜结果表明制备出的纳米(Fe1-xCox)3BO5为多晶棒状, 且具有多折孪晶结构; 磁性测量的结果表明,(Fe1-xCox)3BO5纳米棒在室温下表现出铁磁性, 随着Co含量的增加, 纳米棒的铁磁性逐渐增加, 该纳米棒有望用来研究生物大分子的机械性能. 相似文献
18.
The interplay between the lattice and magnetism in La(Fe11.4Al1.6)C0.02 studied by powder neutron diffraction 下载免费PDF全文
The crystallographic structure and magnetic properties of La(Fell.4Alz.6)C0.02 are studied by magnetic measurernent and powder neutron diffraction with temperature and applied magnetic field. Rietveld refinement shows that La(Fe11.4Al1.6)C0.02 crystallizes into the cubic NaZn13-type with two different Fe sites: FeI (8b) and FeII (96i), and that A1 atoms preferentially occupy the FeII site. A ferromagnetic state can he induced at a medial temperature of 39 K-139 K by an external magnetic field of 0.7 T, and a large lattice is correspondingly found at 100 K and 0.7 T. In all other conditions, La(Fe11.4Al1.6)C0.02 has no net magnetization in the paramagnetic (T 〉 TN = 182 K) or antifer- romagnetic states, and thus keeps its small lattice. Analysis of the Fe Fe bond length indicates that the ferromagnetic state prefers longer Fe-Fe distances. 相似文献
19.
Intense mechanoluminescent (ZnS)1−x(MnTe)x powder samples with x=0.02,0.05,0.10,0.15,0.20 and 0.25 were prepared by simple Solid State Reaction method. All samples were polycrystalline with wurtzite structure. Mechanoluminescence (ML) and Photoluminescence (PL) were observed in all the samples in the red region peaking around 650 nm. The red emission is attributed to the presence of Te along with Mn. ML is attributed to the release of holes due to the stress on the phosphors which then recombine with metastable Mn2+ emitting light. The intensity of ML is found to be strongly dependent on both the impact pressure and composition. The maximum intensities in both ML and PL were observed in samples with x=0.05. 相似文献
20.
Interplay between orbital and magnetic long range order by resonant X-ray scattering in (V1−xCrx)2O3
L. Paolasini S. Di Matteo C. Vettier F. de Bergevin A. Sollier W. Neubeck F. Yakhou P. A. Metcalf J. M. Honig 《Journal of Electron Spectroscopy and Related Phenomena》2001,120(1-3):1-10
Resonant X-ray scattering experiments have been performed in 2.8% Cr-doped V2O3 single crystal at the Vanadium K-photoabsorption edge. Using linear polarization analysis and comparing the angular dependence of scattered photons with structure factor calculations we can discriminate the nature of the different resonant X-ray processes involved in forbidden lattice reflections enhanced by resonances. We present an experimental method to extract information on local properties of edge-atom such as the anisotropy of the local atomic environment, the atomic magnetic moment orientation and orbital ordering. 相似文献