共查询到20条相似文献,搜索用时 0 毫秒
1.
T. V. Kulikova V. A. Bykov A. A. Belozerova K. Yu. Shunyaev 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2016,10(2):356-360
We investigate the processes of crystallization and determined the structure and thermal properties of Al86Ni8Ho6 amorphous alloy in a wide temperature range. A three-stage nature of the crystallization process upon heating to a temperature of 700 K is found. According to data of high-temperature X-ray diffraction analysis, the crystallization of an Al86Ni8Ho6 amorphous ribbon is rather complex: aluminum crystallites grow in the amorphous phase to a temperature of 470 K, a Ho3Ni5Al19 phase is formed above 563 K, and a HoAl3 phase appears above 598 K. The phases of Ho3Ni5Al19 and HoAl3 are retained up to a temperature of 723 K. A three-stage kinetic model of the crystallization process with the reaction sequence is proposed based on calculations by multivariate nonlinear regression. The values of the total activation energy for each crystallization stage reach 239, 378, and 247 kJ/mol. 相似文献
2.
S. V. Gudenko 《JETP Letters》2005,81(8):400-405
Electron paramagnetic resonance (EPR) in a Gd0.14Si0.86 amorphous film is studied over a wide temperature range from 4 to 300 K. The experimental results are analyzed with regard to the strong structural disorder in the system under study. This disorder leads to the formation of droplets, that is, regions with a high density of electronic states. It is shown that the observed EPR signal can be formed only in the double bottleneck regime, and temperature dependences are obtained for the line position and width. The spin-lattice relaxation rates for electrons and Gd ions, the second spectral moment of the line, the ferromagnetic transition temperature, the number of Gd atoms in the droplets, and the product of the electron density of states by the exchange coupling constant between electrons and Gd ions are evaluated from comparison with experimental data. The values obtained corroborate the validity of the assumptions that the double bottleneck conditions are fulfilled and structural and phase nanoscale inhomogeneities exist in the system. 相似文献
3.
I. E. Permyakova A. M. Glezer E. S. Savchenko I. V. Shchetinin 《Bulletin of the Russian Academy of Sciences: Physics》2017,81(11):1310-1316
Variations in the magnetic characteristics (specific saturation magnetization and coercive force) of Co–Fe–Cr–Si–B amorphous alloy (AA) are studied after high-pressure torsion (HPT) and heat treatment. The behavior of AA magnetic properties is analyzed with respect to structural transformations caused by external actions. The corrosion resistance of AA upon transitioning from an amorphous to a crystalline state is investigated. The established optimum annealing and HPT conditions yield a satisfactory combination of the magnetic properties and corrosion resistance of the investigated alloy. 相似文献
4.
This paper presents the results of investigation on the influence of temperature on magnetoelastic characteristics of the
two ring-shaped cores, made of Fe70Ni8Si10B12 amorphous alloy. The cores were annealed for 1 h at 350 and 400°C, respectively. The compressive force F was applied perpendicular to the direction of the magnetizing field H in the sample. Special cylindrical backing enables application of the uniform compressive stress σ to the wound ring sample. A resistive furnace heated the experimental set-up. Results presented in the paper indicate a significant
influence of the temperature on the magnetoelastic characteristics of Fe70Ni8Si10B12 amorphous alloy. Information about the magnetoelastic characteristics of this material may be useful in the magnetoelastic
sensor development. Also this will create new possibilities in the development of physical model of magnetoelastic effect.
相似文献
5.
Yu. A. Aleshchenko A. V. Muratov V. M. Pudalov E. S. Zhukova B. P. Gorshunov F. Kurth K. Iida 《JETP Letters》2012,94(9):719-722
The results of infrared reflectivity measurements for the iron-based high-temperature superconductor Ba(Fe0.9Co0.1)2As2 are reported. The reflectivity is found to be close to unity at frequencies ω lower than 2Δ/h (2Δ is the superconducting gap and h is Planck’s constant). This is evidence for the s
+/− or s
+/+ symmetry of the superconducting order parameter in the studied compound. The infrared reflectivity spectra of Ba(Fe0.9Co0.1)2As2 manifest opening of several superconducting gaps at temperatures lower than critical T
c
. 相似文献
6.
7.
M. Samsel-Czekała G. Kontrym-Sznajd G. Döring W. Schülke J. Kwiatkowska F. Maniawski S. Kaprzyk A. Bansil 《Applied Physics A: Materials Science & Processing》2003,77(1):87-92
A reconstruction technique based on the solution of the Radon transform in terms of Jacobi polynomials is used to obtain the
3D electron momentum density, ϱ(p), from nine high-resolution Compton profiles (CPs) for a Cu0.9Al0.1 disordered alloy single crystal. The method was also applied to theoretical CPs computed within the Korringa–Kohn–Rostoker
coherent potential approximation (KKR-CPA) first-principles scheme for the same nine orientations of the crystal. The experimental
ϱ(p) is in satisfactory agreement with the theoretical ϱ(p), shows most details of the Fermi surface (FS) and exhibits electron correlation effects. We comment on the map of the FS
obtained by folding the reconstructed ϱ(p) into the first Brillouin zone, which yields the occupation number density, ϱ(k). A test of the validity of data via a consistency condition (within our reconstruction algorithm) as well as the propagation
of experimental noise in the reconstruction of both ϱ(p) and ϱ(k) are investigated.
Received: 24 October 2001 / Accepted: 20 January 2002 / Published online: 3 June 2002
RID="*"
ID="*"Corresponding author. Fax: +48-71/344-10-29, E-mail: samsel@int.pan.wroc.pl 相似文献
8.
V. I. Betekhtin P. N. Butenko V. L. Hilarov A. G. Kadomtsev V. E. Korsukov M. M. Korsukova B. A. Obidov 《Physics of the Solid State》2008,50(10):1875-1881
The effect of hydrostatic pressure and uniaxial compression on the relief of an amorphous Fe77Ni1Si9B13 alloy ribbon surface was studied using scanning tunneling and atomic-force microscopy. The fracture surfaces of samples were also studied. It is found that both the initial surfaces and the surfaces of samples subjected to hydrostatic compression or tension, as well as fracture surfaces, are fractal or multifractal, but their fractality parameters are different. Hydrostatic pressure decreases the surface roughness and the average fractal dimension of the surface on both sides of the ribbons. The dependence of the surface fractal characteristics on tension is more complex. Prior to the occurrence of a “critical event” on the surface (formation of a deformation band or a through crack), the Hölder index and the half-width of the singularity spectrum decrease. The correlation is discussed between the fractal characteristics of the ribbon surface and those of a fracture surface, and the role of an excess free volume in the initiation of fracture of amorphous alloys is analyzed. 相似文献
9.
Karol Załęski Janusz Dubowik Iwona Gościańska Bartłomiej Andrzejewski Tomasz Toliński 《Central European Journal of Physics》2011,9(2):558-561
In this paper we report structural, magnetic and transport properties of strongly textured Ni51Mn36Sn13 thin films. The off-stoichiometric Heusler alloy films with 200 nm thickness were sputter-deposited on a MgO(100) substrate
at 500 K and after annealed at 1000 K in UHV conditions. The textured growth was confirmed by x-ray diffraction in Bragg-Brentano
geometry. The temperature dependence of the magnetic properties was measured by VSM and FMR methods. The electron transport
measurements were carried out in function of temperature in 0 Oe and 50 kOe fields. All measurements corroborate the existence
of the martensitic transformation in the film. Furthermore, transport measurements reveal an influence of the magnetic field
on the transition temperature. 相似文献
10.
Yu. I. Golovin V. I. Ivolgin A. I. Tyurin V. A. Khonik 《Physics of the Solid State》2003,45(7):1267-1271
Depth-sensing (indentation) testing is used to study the characteristics of a serrated plastic flow in a Pd40Cu30Ni10P20 bulk amorphous alloy, and the boundaries between the regions of serrated and homogeneous plastic deformation are determined. 相似文献
11.
The ability of a femtosecond laser pulse to manipulate and reverse the magnetization in a ferrimagnetic Gd24Fe66.5Co9.5 thin film was studied experimentally as a function of temperature. For a fixed energy of the laser pulse, the dynamics of magnetization showed different behavior depending on whether the sample temperature was below or above the magnetization compensation point (T M ). The conditions for full ultrafast demagnetization and magnetization reversal were easily achieved below T M , while the same laser excitation caused just 50% demagnetization above T M . This interesting change in magnetization dynamics is qualitatively explained in terms of effective changes in the magnitudes of magnetizations of atomic sublattices. 相似文献
12.
S. Kabi A. Ghosh 《The European Physical Journal B - Condensed Matter and Complex Systems》2011,79(4):377-381
Electrical complex ac conductivity of the compound
Li0.9[Ni1/3Mn1/3Co1/3]O1.95 has been studied in the
frequency range 10 Hz–2 MHz and in the temperature range 93–373 K. It
has been observed that the frequency dependence of the ac conductivity obeys
a power law and the temperature dependence of the ac conductivity is quite
weak. The experimental data have been analyzed in the framework of several
theoretical models based on quantum mechanical tunneling and classical
hopping over barriers. It has been observed that the electron tunneling is
dominant in the temperature range from 93 K to 193 K. A crossover of
relaxation mechanism from electron tunneling to polaron tunneling is
observed at 193 K. Out of the several models discussed, the electron
tunneling and the polaron tunneling models are quite consistent with the
experimental data for the complex ac conductivity. The various parameters
obtained from the fits of the experimental results for the real and
imaginary parts of the conductivity to the predictions of these models are
quite reasonable. 相似文献
13.
V. Yu. Ivanov V. A. Pustovarov E. S. Shlygin A. V. Korotaev A. V. Kruzhalov 《Physics of the Solid State》2005,47(3):466-473
Low-temperature (T = 7 K) time-resolved selectively photoexcited luminescence spectra (2–6 eV) and luminescence excitation spectra (8–35 eV) of wide-bandgap chrysoberyl BeAl2O4, phenacite Be2SiO4, and beryl Be3Al2Si6O18 crystals have been studied using time-resolved VUV spectroscopy. Both the intrinsic luminescence of the crystals and the luminescence associated with structural defects were assigned. Energy transfer to impurity luminescence centers in alexandrite and emerald was investigated. Luminescence characteristics of stable crystal lattice defects were probed by 3.6-MeV accelerated helium ion beams. 相似文献
14.
Pavel Svoboda Pavel Javorský Fuminori Honda Vladimír Sechovský Alois A. Menovsky 《Central European Journal of Physics》2004,2(2):397-418
The tetragonal compound UNi2Si2 exhibits in zero magnetic field three different antiferromagnetic phases belowT
N
=124 K. They are formed by ferromagnetic basal planes, which are antiferromagnetically coupled along thec-axis with the propagation vectorq=(0, 0, q
z
). Two additional order-order magnetic phase transitions are observed below T
N
, namely atT
1=108 K and T
2=40 K in zero magnetic field. All three phases exhibit strong uniaxial anisotropy confining the U moments to a direction parallel
to the c-axis. UNi2Si2 single crystals were studied in detail by measuring bulk thermodynamic properties, such as thermal expansion, resistivity,
susceptibility, and specific heat. A microscopic study using neutron diffraction was performed in magnetic fields up to 14.5
T parallel to the c-axis, and a complex magnetic phase diagram has been determined. Here, we present the analysis of specific-heat data measured
in magnetic fields up to 14 T compared with the results of the neutron-diffraction study and with other thermodynamic properties
of UNi2Si2. 相似文献
15.
E. A. Sherstobitova A. F. Gubkin A. V. Zakharov A. E. Teplykh A. A. Podlesnyak S. N. Gvasaliya J. -G. Park N. V. Baranov A. N. Pirogov 《Physics of the Solid State》2007,49(7):1305-1309
The Tb0.1Tm0.9Co2 compound is investigated using neutron diffraction. It is shown that this compound undergoes an irreversible band metamagnetic transition induced by an external magnetic field. The magnetization of the Co sublattice increases from 0.2 to 0.6 μB. The critical field strength is approximately equal to 1 T at temperatures of 1.8 and 4.0 K. As the temperature increases, the effect of the magnetic field on the magnetic state of the sample weakens and, at 25 K, no noticeable changes are observed in an external field of 0.75 T. The metamagnetic transition at 1.8 K is accompanied by the disappearance of rhombohedral distortions and brings about a lattice expansion by approximately 1%. 相似文献
16.
A theoretical analysis of small-angle neutron scattering is performed for the Fe65Ni35 alloy at a temperature T=0.9T C =450 K. The results obtained indicate the existence of long-wavelength magnetic excitations that do not correspond to spin waves of the Holstein-Primakoff type. The possible nature of these excitations is discussed. 相似文献
17.
Y. V. Kudryavtsev Y. P. Lee Y. J. Yoo M. S. Seo J. M. Kim J. S. Hwang J. Dubowik K. W. Kim E. H. Choi O. Prokhnenko 《The European Physical Journal B - Condensed Matter and Complex Systems》2012,85(1):19
The effect of atomic disorder on the electron transport and the magnetoresistance (MR) of Co2CrAl Heusler alloy (HA) films has been investigated. We show that Co2CrAl films with L21 order exhibit a negative value for the temperature coefficient of resistivity (TCR) in a temperature range of 10 < T < 290 K, and the temperature dependence of electric conductivity varies as T 3/2 similarly to that of the zero-gap semiconductors. The atomic or the site disorder on the way of L21 → B2 → A2 → amorphous state in Co2CrAl HA films causes the deviation from this dependence: reduction in the absolute value of TCR as well as decrease in the resistivity down to ?(T = 293 K) ~ 200 μΩ cm in comparison to ?(T = 293 K) ~ 230 μΩ cm typical for the Co2CrAl films with L21 order. The magnetic-field dependence of MR of the Co2CrAl films with L21 order is determined by two competing contributions: a positive Lorentz scattering and a negative s-d scattering. The atomic disorder in Co2CrAl films drastically changes MR behavior due to its strong influence on the magnetic properties. 相似文献
18.
The optical properties of Fe78Si10B12 ferromagnetic alloy in amorphous, crystalline, and intermediate structural states have been investigated by ellipsometry
in the spectral range of 0.22–18 μm. It is established that alloy crystallization leads to a significant change in the optical
constants and the frequency dependences of the dielectric functions calculated based on these optical constants. The structural
reconstruction under heat treatment leads to an increase in the intensity and shift of interband absorption bands. The plasma
and relaxation frequencies of conduction electrons are determined; their numerical values also depend on the degree of atomic
ordering. 相似文献
19.
The electronic structure and optical properties of the hexagonal intermetallic compound Gd5Si3 are investigated. The spin-polarization calculation of the band spectrum is performed in the local spin density approximation, taking account for the strong electron correlations in the 4 f shell of a Gd ion (LSDA + U method). Optical constants of the compound in the wavelength range of 0.22–15 μm are determined by the ellipsometry technique and some spectral characteristics are calculated. The frequency dependence of optical conductivity in the light quantum absorption region is analyzed on the basis of the calculated electron density of states. 相似文献
20.
V. G. Pushin E. B. Marchenkova A. V. Korolev N. I. Kourov E. S. Belosludtseva A. V. Pushin A. N. Uksusnikov 《Physics of the Solid State》2017,59(7):1321-1331
Comparative studies of physical characteristics (the electrical resistivity, the magnetic susceptibility, the magnetization, the bending deformation, and the degree of shape recovery during subsequent heating) of the Ni54Mn21Ga25 ferromagnetic alloy as-cast and rapidly quenched from melt have been performed in the temperature range 2–400 K. The results are compared to the results of studying the structural–phase transformations by transmission and scanning electron microscopy and X-ray diffraction. It is found that the rapid quenching influences the microstructure, the magnetic state, the critical temperatures, and the specific features of thermoelastic martensite transformations in the alloy. It is found that the resource of the alloy plasticity and thermomechanical bending cyclic stability demonstrates a record-breaking increase in the intercritical temperature range and during subsequent heating. 相似文献