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71.
P. Crespo I. Navarro A. Hernando P. Rodrí guez A. Garcí a Escorial J. M. Barandiar n O. Drbohlav A. R. Yavari 《Journal of magnetism and magnetic materials》1995,150(3):409-416
A ferromagnetic solid solution with a nominal atomic composition Fe70Cu30 and a body-centered structure has been obtained by high-energy ball milling. The decomposition of the system is monitored by X-ray diffraction (XRD), magnetic measurements and Mössbauer spectroscopy. According to XRD, for healing temperatures below 723 K there is only a bcc phase in the material, while for heating temperatures above 723 K a new phase, with a fcc structure, appears, suggesting that the solid solution has decomposed into bcc-Fe and fcc-Cu. However, the magnetic behavior observed during the decomposition process indicates that this evolution is more complex than the simple decomposition into the equilibrium phases. This behavior can be summarized in two points: (1) a decrease in the magnetization at 5 K, and (2) drastic changes in the coercive field with the thermal treatment, soft magnetic behavior for the material in the as-milled state, superparamagnetism for low heating temperatures and a hardening of the material heated to above 723 K, for which the values of the coercive field at room temperature are several times higher than those for the as-milled sample. The Mössbauer spectroscopy performed at room temperature shows that for the heat-treated samples the Fe atoms are in two different phases: a ferromagnetic phase, which evolves to bcc-Fe, and a paramagnetic phase. 相似文献
72.
partially supported by DGICYT 相似文献
73.
74.
Recently, Sr2FeMoO6 has been established as a new colossal magnetoresistance material with substantial low-field magnetoresistance at room temperature and has attracted much attention in the double perovskite family. This material always appears with a certain degree of miss-site disorder where Fe and Mo interchange their positions. Using renormalized perturbation expansion, we calculate the density of states and determine the variation of the critical temperature in the low disorder regime. 相似文献
75.
A. Marcilla M. I. Beltrán R. Navarro 《Journal of Thermal Analysis and Calorimetry》2007,87(2):325-330
The effect of regeneration conditions on
the composition of the gases evolved during the catalytic pyrolysis of low
density (LDPE) and high density polyethylene (HDPE) with HUSY and HZSM5 catalysts
has been analysed by the TG/FTIR technique. When regenerated HUSY was employed,
the evolution of the gases obtained was similar to that with fresh HUSY, indicating
that the regeneration treatment did not affect its properties. Nevertheless
with HZSM5, as the regeneration temperature was higher, the composition of
the gases gradually became more similar to that evolved in the thermal process. 相似文献
76.
77.
X. Jiang G.A. Navarro R. Sassot 《The European Physical Journal C - Particles and Fields》2006,47(1):81-85
We investigate the potential impact of forthcoming Jefferson Lab semi-inclusive polarized deep inelastic scattering proton
measurements in the determination of the sea quark polarization in the nucleons by means of a next to leading order global
QCD analysis. Specifically, we estimate the resulting improvement in the constraints on polarized parton densities for different
flavors, which is found to be significant for up and strange quarks, and the correlation between remaining uncertainty ranges
for each of the parton species.
PACS 12.38.Bx, 13.85.Ni 相似文献
78.
Gabriel Navarro 《Israel Journal of Mathematics》2002,132(1):277-283
Suppose thatG is a finitep-solvable group and letPε Syl
p
(G). In this note, we prove that the character table ofG determines ifN
G(itP)/P is abelian.
Research partially supported by DGICYT. 相似文献
79.
Continuous counter-current chromatographic separation has been carried out in a simulated moving bed system (SMB). We have worked with a SMB pilot plant (8 columns, 4.4 litres of resin each) which allows the continuous withdrawal of two different fractions. A mixture of glucose-fructose has been separated. To calculate the concentration profile within the separator an axial dispersed plug flow model and an equilibrium stage model have been employed; software has been created to simulate the behaviour of the separator. The necessary parameters of the mode: the adsorption equilibrium constant, the height equivalent to a theoretical plate and the bed voidage, have been acquired experimentally from elution chromatography measurements. The results calculated by simulation give a good representation of the experimental concentration profiles; other separations like xylitol-arabitol have been simulated. The influence of some factors like desorbent flow-rate, feed flow-rate and the bed voidage have been studied using the software. Once the system has worked in a two withdrawal way, an extension of the pilot plant has been constructed so as to obtain a third one. The necessary parameters of the three withdrawal model will be studied. 相似文献
80.
Juan F. Navarro Ibrahim Belgharbi María del Carmen Martínez-Belda 《Mathematical Methods in the Applied Sciences》2023,46(1):1032-1044
In this paper, we have performed a numerical investigation of the escape of a particle from two different dynamical systems with the same number of exit channels. We have chosen specific values of the parameters of the systems so that the openings of the potential well in both systems are approximately of the same size. We have found that, in the galactic system, the distribution of the times of escape follows a sequential pattern that has never been detected before. Moreover, we have proved that this pattern is directly related to the geometry of the stable manifolds to the Lyapunov orbits located at the openings of the potential. Finally, we have shown that the different nature of the two systems affects the way the escape occurs, due to the difference in the geometry of the manifolds to the Lyapunov orbits in both systems. 相似文献