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51.
52.
F. Bourdarot A. Bombardi P. Burlet R. Calemczuk G.H. Lander F. Lapierre J.P. Sanchez K. Mattenberger O. Vogt 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,9(4):605-611
We report specific heat and neutron diffraction measurements of seven samples in the solid solution system UxLa1-xS. All samples have the simple fcc NaCl crystal structure. Both specific heat and neutron diffraction confirm the suggestion
from the earlier magnetic measurements that the ferromagnetism disappears abruptly at 0.57. Near there is a doubling of the electronic contribution to the specific heat, as compared to the value of 23 mJ mol-1K-2 in pure US. Around the widths of the nuclear Bragg peaks show a considerable broadening, as well as anomalies in the mean lattice parameter,
as compared to those expected from Vegard's law. A preliminary analysis suggests this broadening may be due to a loss of long
range lattice order near . However, these changes are independent of temperature, so that further experiments are necessary before they can be associated
with the changes in magnetic behavior at .
Received 18 September 1998 相似文献
53.
H. Yi J. Yu S.-I. Lee 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,7(4):509-512
To study the proposed phase separations in doped manganites, we performed Monte-Carlo calculations for the ferromagnetic Kondo
lattice model with strong Hund's coupling between conduction electrons and localized spins. For the practical calculations,
we adopted a one dimensional lattice and treated the spins of the localized t2g electrons semi-classically. A direct evidence of the phase separation is observed from a snapshot of the spatial dependence
of localized spins. No indication of the canted or spiral phases is found in the results of simulations. Further, the calculated
results of the spin structure factor in the phase separation region are well compared with recent experiments.
Received: 1st September 1998 / Revised: 30 October 1998 / Accepted: 27 November
1998 相似文献
54.
P. Vonlanthen J.L. Gavilano B. Ambrosini H.R. Ott Y. Aoki H. Sugawara H. Sato 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,9(1):15-20
We report the results of 69Ga- and 71Ga-NMR measurements on NdGa2 at temperatures between 0.1 and and in applied magnetic fields between zero and 74 kOe. NdGa2 orders antiferromagnetically below and undergoes several metamagnetic transitions in external magnetic fields. In zero applied magnetic field and below the temperature dependence of the spin-lattice relaxation rate T1
-1
(
T
) shows a large linear-in-T term, about two orders of magnitude higher than for the reference compound LaGa2. This strong enhancement confirms the presence of low-energy excitations in the antiferromagnetic phase of NdGa2 as was previously indicated by specific heat data. Above , T1
-1
(
T
) is dominated by an exponential term, which we associate with excitations between the lowest energy levels of the f-electron system. The separation of these energy levels is determined by exchange, crystal-field and Zeeman interactions.
Received 3 September 1998 and Received in final form 3 November 1998 相似文献
55.
In order to improve load capacity and stability of a fluid moving-pressure bearing, at present, measure of cutting grooves on a turning-shaft is generally adopted.The performances of spiral grooves are better in various groovetypes. Therefore, a theoretical analysis and an experimental investigation of the bearing with spiral grooves attract general attention. But the results of most articles published in china are numerical solutions of the computer. Using the methods of parameter perturbation in the paper, an approaching analytical solution of Reynolds equation of the moving-pressure oilfilm-lubricated ball-bearing with spiral grooves has been obtained. We have combined the numerical solutions of the computer, and the influence of the bearing parameters upon the load capacity is discussed; the optimum values of the groove parameter are obtained. The theoretical conclusion of this paper is in good agreement with the experimental data obtained by 651 Institute. 相似文献
56.
Electroorganic synthesis is an environmentally friendly alternative to traditional synthetic methods; however, the application of this strategy is heavily hindered by low product selectivity. Metal–organic frameworks (MOFs) exhibit high selectivity in numerous catalytic reactions; however, poor conductivity heavily limits the application of MOFs in electroorganic synthesis. To realize the electrocatalytic application of MOFs in selective electroorganic synthesis, a practically applicable strategy by suspending ion electrocatalysts in charged MOFs is herein reported. This approach could markedly improve the product selectivity in electroorganic synthesis. In the electrocatalytic oxidative self‐coupling of benzylamine experiments, the imine product selectivity is markedly improved from 61.3 to 94.9 %, when the MOF‐based electrocatalyst is used instead of the corresponding homogeneous electrocatalyst under the identical conditions. Therefore, this work opens a new route to improve the product selectivity in electroorganic synthesis. 相似文献
57.
K. Proke? J. A. Mydosh 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,67(1):1-6
We have studied the unusual low-temperature magnetic phase of Er2Ni2Pb using powder neutron diffraction measurements in zero field down to 460 mK. Our previous neutron diffraction experiments
down to 1.5 K showed that magnetic Bragg reflections seen in Er2Ni2Pb can be indexed by several propagation vectors that partially coexist. All the incommensurate propagation vectors seemed
to disappear in the low temperature limit. The present study, however, shows that reflections belonging to the propagation
vector q’ = (0.47 0 1/2) do not disappear but remain present down to 460 mK. This highly unexpected result suggests that the magnetic
structure described by this propagation vector might not be a simple sine-wave modulation. One interesting possibility here
is a spin-slip structure as the ground state. 相似文献
58.
采用高效液相色谱法研究了宁波市象山港某养殖场悬浮沉积物对壬基酚、辛基酚及双酚A 3种酚类环境激素的吸附行为. 结果表明: 壬基酚、辛基酚及双酚A在悬浮沉积物上的吸附是一个复合动力学过程, 吸附量具有波动特征; 吸附等温线可用Henry线性分配模型及Freundlich模型进行数学描述; 沉积物对3种酚类环境激素的平衡吸附量大小为壬基酚>辛基酚>双酚A; 有机质含量影响壬基酚、辛基酚及双酚A在沉积物中的吸附行为, 3种沉积物的平衡吸附量大小表现为加腐殖酸沉积物>沉积物原样>去除有机质的沉积物; 酚类环境激素在沉积物中的浓度积累增大了养殖水域底栖生物的接触风险. 相似文献
59.
60.