共查询到20条相似文献,搜索用时 31 毫秒
1.
Zhan-Shuo Hu Fei-Yi Hung Shoou-Jinn Chang Kuan-Jen Chen Yi-Wei Tseng Bohr-Ran Huang Bo-Cheng Lin Wei-Yang Chou Jay Chang 《Journal of nanoparticle research》2011,13(10):4757-4763
The photo-current of n-ZnO/p-Si heterojunction photodiodes was improved by embedding Ag nanoparticles in the interface (ZnO/nano-PAg/p-Si), and the ratio between photo- and dark-current increased by about three orders more than that of a n-ZnO/p-Si specimen. The improvement in the photo-current resulted from the light scattering of embedded Ag nanoparticles. The I–V curve of n-ZnO/p-Si degraded after thermal treatment (A-ZnO/p-Si) because the silicon robbed the oxygen from ZnO to form amorphous silicon dioxide and left an oxygen vacancy. Notably,
the properties of ZnO/nano-PAg/p-Si were better in the time-dependent photoresponse under 10 V bias. Ag nanoparticles (15–20 nm) scattered the UV light randomly
and increased the probability for the absorption of ZnO to enhance the properties of the photodiode. 相似文献
2.
A comparative investigation of the magnetic properties of amorphous nanogranular composites (Co41Fe39B20)
x
(SiO
n
)100 − x
and (Co86Nb12Ta2)
x
(SiO
n
)100 − x
has been performed in the subpercolation region at temperatures in the range 4.2–300 K. The thermomagnetic dependences in
the range 4.2–300 K and the processes of magnetization reversal and remanent magnetization relaxation at liquid-helium temperatures
have been studied. It has been established that the average anisotropy constants of amorphous nanograins are equal to 3.6–7.0
kJ/m3 for the (Co41Fe39B20)
x
(SiO
n
)100 − x
composites and 5–8 kJ/m3 for the (Co86Nb12Ta2)
x
(SiO
n
)100 − x
composites. The fundamental differences in the concentration dependences of the anisotropy constant K
eff and the coercive force H
C
have been revealed for the two systems under investigation. It has been demonstrated that, as the concentration of the metal
phase increases, the quantities K
eff and H
C
increase for the (Co86Nb12Ta2)
x
(SiO
n
)100 − x
composites and decrease for the (Co41Fe39B20)
x
(SiO
n
)100 − x
composites. 相似文献
3.
M. van Leeuwen 《The European Physical Journal C - Particles and Fields》2009,61(4):569-574
We present selected recent results of multi-hadron correlation measurements in azimuth and pseudorapidity at intermediate
and high p
T
in Au+Au collisions at
, from the STAR experiment at RHIC. At intermediate p
T
, measurements are presented that attempt to determine the origin of the associated near-side (small Δφ) yield at large pseudo-rapidity difference Δη that is found to be present in heavy ion collisions. In addition, results are reported on new multi-hadron correlation measures
at high-p
T
that use di-hadron triggers and multi-hadron cluster triggers with the goal to constrain the underlying jet kinematics better
than in the existing measurements of inclusive spectra and di-hadron correlations. 相似文献
4.
V. R. Galakhov M. Neumann D. G. Kellerman 《Applied Physics A: Materials Science & Processing》2009,94(3):497-500
X-ray absorption, resonant X-ray emission, and X-ray photoelectron spectroscopical methods have been applied for the study
of the electronic structure of defective lithium cobaltites Li
x
CoO2 (0.6≤x≤1.0). Resonant O K
α X-ray emission spectra of LiCoO2 showed localized excitonic states due to a dd transition between occupied and unoccupied Co 3d states. On the base of measurements of Co 3s X-ray photoelectron, Co 2p, and O 1s X-ray absorption spectra, it was established that in defective cobaltites the electronic holes are localized mainly in O
2p states. An evidence of phase separation in Li
x
CoO2 has been found. It was shown that the semiconductor-to-metal transition in Li
x
CoO2 (x<0.76) at about 160 K is not accompanied by changes in the Co 3d electronic configuration which remains 3d
6. 相似文献
5.
The ground state degeneracy of an SU(N)
k
topological phase with n quasiparticle excitations is a relevant quantity for quantum computation, condensed matter physics, and knot theory. It is
an open question to find a closed formula for this degeneracy for any N >2. Here we present the problem in an explicit combinatorial way and analyze the case N = 3. While not finding a complete closed-form solution, we obtain generating functions and solve some special cases. 相似文献
6.
V. V. Mesilov V. R. Galakhov A. S. Semenova D. G. Kellerman L. V. Elokhina 《Physics of the Solid State》2011,53(2):271-275
The electronic structure and specific features of the structure of nonstoichiometric cobaltite Li
x
Na
y
CoO2 (x = 0.42, y = 0.36) have been studied comprehensively. The calculated multiplet for the lowspin state of the Co3+ ion agrees with the experimental spectra. It has been established using X-ray absorption spectra measured in the total photoelectric
effect yield and total fluorescence yield modes that the Li
x
Na
y
CoO2 cobaltite is stoichiometric with respect to the alkali metal near its surface and is defective inside. It has been demonstrated
that the charge compensation in the case of an alkali metal deficit in LixNayCoO2 is due to holes in O 2p states. 相似文献
7.
V. Cirigliano H. Neufeld H. Pichl 《The European Physical Journal C - Particles and Fields》2004,35(1):53-65
We present a detailed numerical study of the Ke3 decays to
in chiral perturbation theory with virtual photons and leptons. We describe the extraction of the CKM matrix element |Vus| from the experimental Ke3 decay parameters. We propose a consistency check of the K + e3 and K0e3 data that is largely insensitive to the dominating theoretical uncertainties, in particular the contributions of
. Our analysis is highly relevant in view of the recent high statistics measurement of the K + e3 branching ratio by E865 at Brookhaven which does not indicate any significant deviation from CKM unitarity but rather a discrepancy with the present K0e3 data.Received: 22 January 2004, Published online: 30 April 2004Work supported in part by IHP-RTN, Contract No. HPRN-CT2002-00311 (EURIDICE) and by Acciones Integradas, Project No. 19/2003 (Austria), HU2002-0044 (MCYT, Spain) 相似文献
8.
Ab initio calculations were performed to investigate the electronic structure and the Fermi surface of the newly discovered
low-temperature superconductor: fluorine-doped WO3. We find that F doping provides the transition of the insulating tungsten trioxide into a metallic-like phase WO3 − x
F
x
, where the near-Fermi states are formed mainly from W 5d with admixture of O 2p orbitals. The cooperative effect of fluorine additives in WO3 consists in change of electronic concentration as well as the lattice constant. At probing their influence on the near-Fermi
states separately, the dominant role of the electronic factor for the transition of tungsten oxyfluoride into superconducting
state was established. The volume of the Fermi surface gradually increases with the increase of the doping. In the sequence
WO3 → WO2.5F0.5 the effective atomic charges of W and O ions decrease, but much less, than it is predicted within the idealized ionic model—owing
to presence of the covalent interactions W-O and W-F. 相似文献
9.
Maria Kaczmarczyk 《Central European Journal of Physics》2011,9(1):78-87
Our earlier results obtained for moments of inertia (M) in the case of 54 rotational level bands built on the ground state of actinide nuclei are taken for further analysis. In
the current paper, resulting dynamic rotational characteristics, such as a
0, a
1, s
0 and the R
4/2 parameter, are studied from the standpoint of their dependence on the valence nucleon number product N
p
N
n
and on the variable P = N
p
N
n
/(N
p
+ N
n
). New features of the nuclei deformation phenomenon in the actinide area arise when their dynamic rotational characteristics,
mentioned above, are plotted in such a way as shown in the current work. The method of analysis presented here makes it possible
to reveal nuclei with valence nucleon numbers for which the nuclear interactions are notable and those in which they are inconspicuous.
E. g. when N
p
N
n
< 200 and P < 6 the strength of nuclear interaction gradually decreases with the increase of these variables. The strength of the nuclear
interaction does not change significantly for N
p
N
n
> 200 and P > 6 — the rotational characteristics stabilise. Moreover, it is possible to establish the P variable as representing the effective number of interactions of each valence nucleon with those of the other type. 相似文献
10.
The dielectron widths of Y(nS)(n = 1, …, 7) and vector decay constants are calculated using the relativistic string Hamiltonian with a universal interaction.
For Y(nS) (n = 1, 2, 3) the dielectron widths and their ratios are obtained in full agreement with the latest CLEO data. For Y(10580)
and Y(11020) a good agreement with experiment is reached only if the 4S-3D mixing (with a mixing angle θ = 27°± 4°) and 6S-5D mixing (with θ = 40°±5°) are taken into account. The possibility to observe higher “mixed D-wave” resonances, $
\tilde \Upsilon
$
\tilde \Upsilon
(n
3
D
1) with n = 3, 4, 5 is discussed. In particular, $
\tilde \Upsilon
$
\tilde \Upsilon
(≈11120), originating from the pure 53
D
1 state, can acquire a rather large dielectron width, ∼130 eV, so that this resonance may become manifest in the e
+
e
− experiments. On the contrary, the widths of pure D-wave states are very small, Γ
ee
(n
3
D
1)≤ 2 eV. 相似文献
11.
D. Mourad G. Czycholl 《The European Physical Journal B - Condensed Matter and Complex Systems》2010,78(4):497-507
Zero-dimensional nanocrystals, as obtained by chemical synthesis, offer a broad range of applications, as their spectrum and
thus their excitation gap can be tailored by variation of their size. Additionally, nanocrystals of the type A
x
B1-
x
C can be realized by alloying of two pure compound semiconductor materials AC and BC, which allows for a continuous tuning
of their absorption and emission spectrum with the concentration x. We use the single-particle energies and wave functions calculated
from a multiband sp
3 empirical tight-binding model in combination with the configuration
interaction scheme to calculate the optical properties of
Cd
x
Zn1-
x
Se nanocrystals with a spherical shape. In contrast to common mean-field approaches like the virtual crystal approximation
(VCA), we treat the disorder on a microscopic level by taking into account a finite number of realizations for each size and
concentration.
We then compare the results for the optical properties with recent experimental data and calculate the optical bowing coefficient
for further sizes. 相似文献
12.
Saskia Mioduszewski 《The European Physical Journal C - Particles and Fields》2009,61(4):741-745
Results on high-p
T
probes shown at the Hard Probes 2008 Conference are summarized, with an appreciation of the improvements in precision of
the measurements and experimental techniques since the beginning of RHIC operation. Particular attention is given to the latest
measurements of the nuclear modification factor of identified particles, photon-hadron correlation measurements, and full
jet reconstruction. 相似文献
13.
N. K. Pruthi 《The European Physical Journal C - Particles and Fields》2009,62(1):165-167
In this paper we look for correlations between intermediate p
T
particle pairs and the v
2 of the remaining low p
T
particles. We find that the shape of the flow vector distribution, which is calculated from all low p
T
tracks, depends in a non-trivial way on the angular separation between the high p
T
particle pairs in the event. Our analysis is based on 200 GeV Au+Au collisions measured with the STAR detector. 相似文献
14.
T. B. Charikova N. G. Shelushinina G. I. Kharus O. E. Sochinskaya A. A. Ivanov 《Physics of the Solid State》2009,51(11):2229-2234
The temperature dependences of the resistivity of single-crystal films of the Nd2 − x
Ce
x
CuO4 + δ
n-type superconductors with x = 0.14 (underdoped region) and x = 0.15 (optimal doping region) and different degrees of disorder δ have been investigated in various magnetic fields (B ‖ c, J ‖ ab) in the temperature range 0.4–300 K. It has been demonstrated that there are differences in the behavior of the dependences
of the slope of the upper critical field $
(dB_{c2} /dT)_{T \to T_c }
$
(dB_{c2} /dT)_{T \to T_c }
on the disorder parameter for the underdoped samples (x = 0.14) and the samples with the optimal doping (x = 0.15). The study of the dependence of the slope of the upper critical field on the degree of disorder has made it possible
to discriminate experimentally between the superconductors with the d pairing and anisotropic s pairing. It has been revealed that the relative stability of the n-type superconductor with the optimal doping with respect to disordering is possibly due to the strong anisotropy of impurity
scattering with symmetry of the d type. 相似文献
15.
E. V. Bogdanov N. B. Brandt N. Ya. Minina S. S. Shirokov A. E. Yunovich 《Moscow University Physics Bulletin》2010,65(5):402-406
New experimental data are presented on the effects of uniaxial compression of up to 4 kbar along the [110] and [1$
\bar 1
$
\bar 1
0] crystallographic directions on the spectra of electroluminescence and the current-voltage characteristics of diodes based
on n-Al
x
Ga1 − x
As/GaAs
y
P1 − y
/p-Al
x
Ga1 − x
As (y = 0.84) heterostructures that were designed for injection lasers. With increasing pressure, the spectra show a shift to shorter
wavelengths, reaching 25 meV at 3 kbar; the intensity increases 2–3 times as well. Numerical calculations were carried out
on the band structure of the investigated heterostructures under compression along the [110] axis, which indicate the increase
in the effective band gap in the quantum well (QW) GaAs
y
P1 − y
, with a pressure coefficient of about 8.5 meV/kbar and reduction of the barrier height at the boundaries of the QW. The calculations
predict the possibility that light and heavy holes crossover at pressures above 4.5–5 kbar. The increase in the effective
band gap completely describes the experimental data on the shift of the electroluminescence spectra. The mixing of light and
heavy holes when approaching the band crosspoint is the probable cause of an increase in the intensity of radiation under
uniaxial compression. 相似文献
16.
J. Gasser B. Kubis N. Paver M. Verbeni 《The European Physical Journal C - Particles and Fields》2005,40(2):205-227
Motivated by recent experimental results and ongoing measurements, we review the chiral perturbation theory prediction for
decays. Special emphasis is given to the stability of the inner bremsstrahlung-dominated relative branching ratio versus the K
e3 form factors, and on the separation of the structure-dependent amplitude in differential distributions over the phase space. For the structure-dependent terms, an assessment of the order p
6 corrections is given, in particular, a full next-to-leading order calculation of the axial component is performed. The experimental analysis of the photon energy spectrum is discussed, and other potentially useful distributions are introduced.Received: 9 December 2004, Published online: 21 February 2005PACS:
13.20.Eb, 11.30.Rd, 12.39.Fe 相似文献
17.
The capacitance-voltage and current-voltage characteristics of the n-CdS/p-CdTe heterosystem are investigated. Analysis of these characteristics demonstrates that the CdTe1?x S x solid solution formed at the n-CdS/p-CdTe heterointerface is inhomogeneous in both the conductivity and composition. The thickness of solid solutions is estimated from the capacitance-voltage characteristics. It is shown that, for the n-CdS/p-CdTe heterosystem, the current-voltage characteristic in the current density range 10?8-10?5 A cm?2 is governed by the thermal electron emission, whereas the current in the heterostructure at current densities in the range 10?4-10?2 A cm?2 is limited by recombination of charge carriers in the electroneutral region of the CdTe1?x S x solid solution. The lifetime and the diffusion length of minority charge carriers in the CdTe1?x S x solid solution and the surface recombination rate at the interface between the CdS layer and the CdTe1?x S x solid solution are determined. It is demonstrated that the n-CdS/p-CdTe heterostructure operates as a p-i-n structure in which CdTe is a p layer, CdTe1?x S x is an i layer, and CdS is an n layer. 相似文献
18.
We obtain exact results in α′ for open and closed A-model topological string amplitudes on a large class of toric Calabi-Yau threefolds by using their correspondence with five
dimensional gauge theories. The toric Calabi-Yaus that we analyze are obtained as minimal resolution of cones over Y
p,q
manifolds and give rise via M-theory compactification to SU(p) gauge theories on . As an application we present a detailed study of the local case and compute open and closed genus zero Gromov-Witten invariants of the orbifold. We also display the modular structure of the topological wave function and give predictions for higher genus amplitudes.
The mirror curve in this case is the spectral curve of the relativistic A
1 Toda chain. Our results also indicate the existence of a wider class of relativistic integrable systems associated to generic
Y
p,q
geometries. 相似文献
19.
Y. Xiao Y. Su C. M. N. Kumar C. Ritter R. Mittal S. Price J. Perßon Th. Brückel 《The European Physical Journal B - Condensed Matter and Complex Systems》2011,82(2):113-121
The physical and structural properties of Fe1.11Te and
Fe1.11Te0.5Se0.5 have been investigated by means of
X-ray and neutron diffraction as well as physical property
measurements. For the Fe1.11Te compound, the structure
distortion from a tetragonal to monoclinic phase takes place at 64 K
accompanied with the onset of antiferromagnetic order upon cooling.
The magnetic structure of the monoclinic phase was confirmed to be
of antiferromagnetic configuration with a propagation vector
k = (1/2, 0, 1/2) based on Rietveld refinement of neutron
powder diffraction data. The structural/magnetic transitions are
also clearly visible in magnetic, electronic and thermodynamic
measurements. For superconducting Fe1.11Te0.5Se0.5
compound, the superconducting transition with T
c
= 13.4 K
is observed in the resistivity and ac susceptibility measurements.
The upper critical field H
c2 is obtained by measuring
the resistivity under different magnetic fields. The Kim’s critical
state model is adopted to analyze the temperature dependence of the
ac susceptibility and the intergranular critical current density is
calculated as a function of both field amplitude and temperature.
Neutron diffraction results show that
Fe1.11Te0.5Se0.5 crystalizes in tetragonal structure
at 300 K as in the parent compound Fe1.11Te and no structural
distortion is detected upon cooling to 2 K. However an anisotropic
thermal expansion anomaly is observed around 100 K. 相似文献
20.
I. V. Ovchinnikov T. A. Ivanova A. N. Turanov R. R. Garipov 《Physics of the Solid State》2009,51(10):2058-2063
Significant differences in the manifestation of spin-crossover properties of the mesogen compounds [FeL
2]X with oxysalicylidene-N′-ethyl-N-ethylenediamine ligands L and anions X = PF6− and SCH− have been found by means of electron paramagnetic resonance. The electron paramagnetic resonance data and the quantum-chemical
calculation within the density functional theory enables us to establish that the observed specific features are associated
with the incorporation of the SCH− ion into the first coordination sphere of the Fe(III) ion. The role of the transition of the material to the liquid-state
phase in the formation of a low-dimensional (two-dimensional) structure with stronger intermolecular interactions has been
revealed. 相似文献