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1.
Heavy ion irradiation in the electronic stopping power region induces macroscopic dimensional change in metallic glasses and introduces magnetic anisotropy in some magnetic materials. The present work is on the irradiation study of ferromagnetic metallic glasses, where both dimensional change and modification of magnetic anisotropy are expected. Magnetic anisotropy was measured using Mössbauer spectroscopy of virgin and irradiated Fe40Ni40B20 and Fe40Ni38Mo4B18 metallic glass ribbons. 90 MeV 127I beam was used for the irradiations. Irradiation doses were 5×1013 and 7.5×1013 ions/cm2. The relative intensity ratios D 23 of the second and third lines of the Mössbauer spectra were measured to determine the magnetic anisotropy. The virgin samples of both the materials display in-plane magnetic anisotropy, i.e., the spins are oriented parallel to the ribbon plane. Irradiation is found to cause reduction in magnetic anisotropy. Near-complete randomization of magnetic moments is observed at high irradiation doses. Correlation is found between the residual stresses introduced by ion irradiation and the change in magnetic anisotropy. 相似文献
2.
Demchenko N. N. Ivanovskikh R. D. 《Journal of Experimental and Theoretical Physics》2022,134(1):112-122
Journal of Experimental and Theoretical Physics - Two-dimensional wave electroconvective flows and transient processes in a low conducting nonisothermal liquid filling a parallel-plate horizontal... 相似文献
3.
Pustovarov V. A. Ivanovskikh K. V. Khatchenko Yu. E. Ivanov V. Yu. Bettinelli M. Shi Q. 《Physics of the Solid State》2019,61(5):758-762
Physics of the Solid State - The spectroscopic characteristics and luminescence decay kinetics of Sr9Sc(PO4)7:Pr3+(1%) were investigated using synchrotron radiation of ultraviolet (UV), vacuum... 相似文献
4.
Amita Gupta Alexei Yu Ganin Parmanand Sharma Vikrant Agnihotri LM Belova KV Rao Mikhail E Kozlov AA Zakhidov RH Baughman 《Pramana》2002,58(5-6):1051-1059
We present studies of novel nanocomposites of BiNi impregnated into the structure of opals as well as inverse opals. Atomic force microscopy and high resolution elemental analyses show
a highly ordered structure and uniform distribution of the BiNi filler in the matrix. These BiNi-based nanocomposites are
found to exhibit distinct ferromagnetic-like ordering with transition temperature of about 675 K. As far as we know there
exists no report in literature on any BiNi compound which is magnetic. 相似文献
5.
K. V. Ivanovskikh V. A. Pustovarov B. V. Shul’gin M. Kirm 《Physics of the Solid State》2005,47(8):1446-1449
Time-resolved excitation and emission spectra of SrF2: Er3+ upon selective excitation with synchrotron radiation in the VUV and ultrasoft x-ray ranges at T = 8 K were studied. The VUV luminescence of SrF2: Er3+ derives from high-energy interconfiguration 4f105d-4f11 transitions in the Er3+ ion. The VUV emission spectrum revealed, in addition to the 164.5-nm band (millisecond-range kinetics), a band at 146.4 nm (with a decay time of less than 600 ps). The formation of excitation spectra for the f-f and f-d transitions in the Er3+ ion is discussed. 相似文献
6.
Using the recent results for the surface current density on cylindrical surfaces of arbitrary cross-section producing uniform
interior magnetic field we propose a method for obtaining solutions of Bean’s critical state model for general cylindrical
samples. The method uses the technique of conformal mapping to express the sample surface and the flux-fronts in terms of
a set of coefficients that depend on a parameter. The flux-fronts are to be determined by solving a system of nonlinear ordinary
differential equations for the coefficients. Retaining only a certain finite number of leading coefficients we get an approximate
solution. The procedure is illustrated by considering two cyclindrical samples — one with an elliptical cross-section and
the other with a non-elliptical cross-section. The virgin curve and small and large magnetization hysteresis loops for the
two samples are obtained. 相似文献
7.
We present a novel ac susceptibility technique for the study of vortex creep in superconducting thin films. With this technique
we study the dynamics of dilute vortices in c-axis oriented Y-123, Hg-1212, and Tl-1212 thin films, as well as a axis oriented Hg-1212 thin films. Results on the Hg-1212 and Tl-1212 thin films indicate that dislocation-mediated plastic
flux creep of single vortices dominates at low temperatures and fields. As the temperature (or the field) is increased, the
increasing vortex-vortex interactions promote a collective behavior, which can be characterized by elastic creep with a non-zero
μ exponent. Also, in some of these samples effects of thermally assisted quantum creep are visible up to 45 K in some of these
samples. In Y-123 thin films, creep is found to be collective down to the lowest temperatures and fields investigated, while
the quantum creep persists only up to 10–11 K. 相似文献
8.
JM Ogiegło A Zych KV Ivanovskikh T Jüstel CR Ronda A Meijerink 《The journal of physical chemistry. A》2012,116(33):8464-8474
Lu(3)Al(5)O(12) (LuAG) doped with Ce(3+) is a promising scintillator material with a high density and a fast response time. The light output under X-ray or γ-ray excitation is, however, well below the theoretical limit. In this paper the influence of codoping with Tb(3+) is investigated with the aim to increase the light output. High resolution spectra of singly doped LuAG (with Ce(3+) or Tb(3+)) are reported and provide insight into the energy level structure of the two ions in LuAG. For Ce(3+) zero-phonon lines and vibronic structure are observed for the two lowest energy 5d bands and the Stokes' shift (2 350 cm(-1)) and Huang-Rhys coupling parameter (S = 9) have been determined. Tb(3+) 4f-5d transitions to the high spin (HS) and low spin (LS) states are observed (including a zero-phonon line and vibrational structure for the high spin state). The HS-LS splitting of 5400 cm(-1) is smaller than usually observed and is explained by a reduction of the 5d-4f exchange coupling parameter J by covalency. Upon replacing the smaller Lu(3+) ion with the larger Tb(3+) ion, the crystal field splitting for the lowest 5d states increases, causing the lowest 5d state to shift below the (5)D(4) state of Tb(3+) and allowing for efficient energy transfer from Tb(3+) to Ce(3+) down to the lowest temperatures. Luminescence decay measurements confirm efficient energy transfer from Tb(3+) to Ce(3+) and provide a qualitative understanding of the energy transfer process. Co-doping with Tb(3+) does not result in the desired increase in light output, and an explanation based on electron trapping in defects is discussed. 相似文献
9.
Pustovarov V. A. Ivanovskikh K. V. Khatchenko Yu. E. Bettinelli M. Shi Q. 《Physics of the Solid State》2019,61(5):752-757
Physics of the Solid State - The luminescent characteristics of K3LuSi2O7:Pr3+ (1%), which is a promising optical material for the use as a scintillator, have been studied using a set of... 相似文献
10.
K.V. Ivanovskikh A. Meijerink A. Speghini C. Ronda M. Bettinelli 《Journal of luminescence》2010,130(5):893-16384
The silicates Ca3Sc2Si3O12, Ca3Y2Si3O12 and Ca3Lu2Si3O12, both undoped and doped with Pr3+ ions, have been synthesized by solid-state reaction at high temperature. The luminescence spectroscopy and the excited state dynamics of the materials have been studied upon VUV and X-ray excitation using synchrotron radiation. All doped samples have shown efficient 5d-4f emission upon direct VUV excitation of 5d levels, but only Ca3Sc2Si3O12:Pr3+ shows luminescence upon interband VUV or X-ray excitation. The VUV excited emission spectra of Ca3Y2Si3O12:Pr3+ and Ca3Lu2Si3O12:Pr3+ show features attributed to emission from two distinct sites accommodating the Pr3+ dopant. The decay kinetics of the Pr3+ 5d-4f emission in Ca3Sc2Si3O12:Pr3+ upon VUV excitation across the band gap are characterized by decay times in the range 25-28 ns with no significant rise after the excitation pulse. They appear to be faster upon X-ray irradiation than for VUV excitation. Weak afterglow components are attributed to defect luminescence. 相似文献