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11.
We examine a local realist bound in the case of a one-atom micromaser. It is shown that such a bound is violated using a simplified
treatment of the micromaser. We consider the effect of dissipation in a proposed experiment with the real micromaser. It is
seen that the magnitude of violation of a Bell-type inequality depends significantly on the cavity parameters. 相似文献
12.
Silica-bonded S-sulfonic acid (SBSSA) is employed as a recyclable catalyst for the synthesis of α-amino nitriles. These syntheses were performed via a one-pot three-component condensation of aldehydes, amines, and trimethylsilyl cyanide under mild reaction conditions at room temperature. 相似文献
13.
F. Ronning E.D. Bauer T. Park N. Kurita T. Klimczuk R. Movshovich A.S. Sefat D. Mandrus J.D. Thompson 《Physica C: Superconductivity and its Applications》2009,469(9-12):396-403
We review the properties of Ni-based superconductors which contain Ni2X2 (X = As, P, Bi, Si, Ge, B) planes, a common structural element found also in the recently discovered FeAs superconductors. Strong evidence for the fully gapped nature of the superconducting state has come from field dependent thermal conductivity results on BaNi2As2. Coupled with the lack of magnetism, the majority of evidence suggests that the Ni-based compounds are conventional electron–phonon mediated superconductors. However, the increase in Tc in LaNiAsO with doping is anomalous, and mimics the behavior in LaFeAsO. Furthermore, comparisons of the properties of Ni- and Fe-based systems show many similarities, particularly with regards to structure–property relationships. This suggests a deeper connection between the physics of the FeAs superconductors and the related Ni-based systems which deserves further investigation. 相似文献
14.
Athena S. Sefat Andriy M. Palasyuk Sergey L. Bud’ko John D. Corbett Paul C. Canfield 《Journal of solid state chemistry》2008,181(2):282-293
Single crystals of CeAu4Si2 and CeAu2Si2 have been grown out of ternary fluxes rich in Au, and the former, also by sintering the stoichiometric composition at 750 °C. The single-crystal X-ray refinement result for CeAu4Si2 is orthorhombic, Cmmm (No. 65, Z=2), different from a tetragonal result found from an X-ray powder diffraction refinement [H. Nakashima, et al., J. Alloys Compds. 424 (2006) 7]. For CeAu2Si2, this is the first report of the stoichiometric crystalline phase, in the known tetragonal I4/mmm structure. The anisotropic field- and temperature-dependent magnetizations, as well as specific heat and resistivity data are compared. Although both compounds have related structural packing, they present unique magnetic features. CeAu2Si2 is a typical antiferromagnet with TN=8.8(1) K and CeAu4Si2 features a ferromagnetic component below Tc=3.3(1) K. Both phases have effective moments close in value to that of free Ce3+. 相似文献
15.
C.A. Bridges A.S. Sefat L. Cranswick M.P. Paranthaman 《Journal of solid state chemistry》2011,184(4):830-842
The influence of Bi3+ on the structural and magnetic properties of the rare-earth-containing perovskites REFe0.5Mn0.5O3 (RE=La,Nd) was studied, and the limit of bismuth substitution was determined to be x≤0.5 in BixRE1−xFe0.5Mn0.5O3+δ (RE=La,Nd) at ambient pressure. Crystal structures in both La and Nd series were determined to be GdFeO3-type Pnma with the exception of the Bi0.3La0.7Fe0.5Mn0.5O3 sample, which is monoclinic I2/a in the a−b−b− tilt scheme. The samples undergo a transition to G-type antiferromagnetic order along with a weak ferromagnetic component, mixed with cluster-glass type behavior. The substitution of bismuth into the lattice results in a drop in TN relative to the lanthanide end-members. Long range ordering temperatures TN in the range 240-255 K were observed, with a significantly lower ordered magnetic moment in the case of lanthanum (M∼1.7-1.9 μB) than in the case of neodymium (M∼2.1 μB). 相似文献
16.
Dr. Sefat Alwarsh Yi Xu Prof. Steven Y. Qian Prof. Matthias C. McIntosh 《Angewandte Chemie (International ed. in English)》2016,55(1):355-358
Breslow intermediates that bear radical‐stabilizing N substituents, such as benzyl, cinnamyl, and diarylmethyl, undergo facile homolytic C? N bond scission under mild conditions to give products of formal [1,3] rearrangement rather than benzoin condensation. EPR experiments and computational analysis support a radical‐based mechanism. Implications for thiamine‐based enzymes are discussed. 相似文献
17.
Single crystal X-ray diffraction data indicate that the R2Co3Zn14 (R=Gd, Y) phase crystallizes non-stoichiometrically with a mixed occupancy of Co/Zn atoms on the 12-coordinated transition metal site and one of the three zinc sites. The crystals are rhombohedral with R-3m space group. Magnetization measurements provide no evidence of localized 3d electron moment in Y2Co2.3Zn14.7 which is non-magnetic down to 1.8 K. Thermodynamic and transport measurements on two Gd2Co3+xZn14−x crystals reveal that the extra cobalt influences temperature below which the samples enter into an antiferromagnetic state: TN=31.5(3) K for Gd2Co3Zn14 and 28(1) K for Gd2Co4.2Zn12.8. A lower magnetic ordering temperature of Tmag=6.0(2) K is common in both Gd samples. 相似文献
18.
Walter?O.?UhoyaEmail author Georgiy?M.?Tsoi Yogesh?K.?Vohra Athena?S.?Sefat Samuel?T.?Weir 《The European Physical Journal B - Condensed Matter and Complex Systems》2014,87(3):68
Electrical transport and structural characterizations of isoelectronically substituted Ba(Fe0.9Ru0.1)2As2 have been performed as a function of pressure up to ~ 30 GPa and temperature down to ~ 10 K using designer diamond anvil cell. Similar to undoped members of the AFe2As2 (A = Ca, Sr, Ba) family, Ba(Fe0.9Ru0.1)2As2 shows anomalous a-lattice parameter expansion with increasing pressure and a concurrent ThCr2Si2 type isostructural (I4/mmm) phase transition from tetragonal (T) phase to a collapsed tetragonal (cT) phase occurring between 12 and 17 GPa where the a is maximum. Above 17 GPa, the material remains in the cT phase up to 30 GPa at 200 K. The resistance measurements show evidence of pressure-induced zero resistance that may be indicative of high-temperature superconductivity for pressures above 3.9 GPa. The onset of the resistive transition temperature decreases gradually with increasing pressure before completely disappearing for pressures above ~ 10.6 GPa near the T-cT transition. We have determined the crystal structure of the high-T c phase of Ru-doped BaFe2As2 to remain as tetragonal (I4/mmm) by analyzing the X-ray diffraction pattern obtained at 10 K and 9.7 ± 0.7 GPa, as opposed to inferring the structural transition from electrical resistance measurement, as in a previous report [S.K. Kim, M.S. Torikachvili, E. Colombier, A. Thaler, S.L. Bud’ko, P.C. Canfield, Phys. Rev. B 84, 134525 (2011)]. 相似文献
19.
An analytical iterative procedure has been established to determine the amplitude of a laser beam propagating through an active
medium. The treatment is valid for both homogeneous and inhomogeneous broadening, and for arbitrary inhomogeneities of the
parameters characterizing the active medium, namely, the refractive index, the small-signal gain and the saturation intensity.
After a supplementary approximation, a thin-sheet gain approach is derived from the first iteration. The formalism enables
us to provide analytical criteria for evaluating both the accuracy of each iteration and the propagation distances for which
the thin-sheet solution can be used.
This revised version was published online in November 2006 with corrections to the Cover Date. 相似文献
20.
Athena S. Sefat David J. Singh V. Ovidiu Garlea Yuri L. Zuev Michael A. McGuire Brian C. Sales 《Physica C: Superconductivity and its Applications》2011,471(5-6):143-149
We show using a combination of powder X-ray and neutron diffraction, first-principles calculations, temperature- and field-dependent magnetization, heat capacity and resistivity data that the superconducting behavior of ‘Sr4V2O6Fe2As2’ is dependent on synthesis conditions, particularly, heating profiles result in unintentional chemical doping. This compound can be tuned from a state in which the vanadium electrons are itinerant with a high electronic density of states, to a state where the vanadium-oxide layers are insulating and presumably magnetic. 相似文献