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1.
Thin films of CdSxTe1-x were deposited by the pulse electrodeposition technique using cadmium sulfate, sodium thiosulfate, and tellurium dioxide on titanium and conducting glass substrates. Structural studies indicated the formation of polycrystalline films possessing hexagonal structure. The resistivity varies from 53 Ω cm to 8 Ω cm as the stochiometric coefficient “x” value decreases from 1 to 0. The carrier concentration increases with CdTe concentration. It is observed that as the post-heat treatment temperature increases, the photosensitivity also increases. It is observed that a post-heat treatment temperature of 550 °C results in high photosensitivity as well as low light resistance. The optical constants, refractive index (n) and extinction coefficient (k) were evaluated from the transmission spectra of the films of different composition.  相似文献   

2.
Data on K e4 decays allow one to extract experimental information on the elastic π π scattering amplitude near threshold, and to confront the outcome of the analysis with predictions made in the framework of QCD. These predictions concern an isospin symmetric world, while experiments are carried out in the real world, where isospin-breaking effects—generated by electromagnetic interactions and by the mass difference of the up and down quarks—are always present. We discuss the corrections required to account for these, so that a meaningful comparison with the predictions becomes possible. In particular, we note that there is a spectacular isospin-breaking effect in K e4 decays. Once it is taken into account, the previous discrepancy between NA48/2 data on K e4 decays and the prediction of π π scattering lengths disappears.  相似文献   

3.
The paper reports on an ellipsometric study of the optical properties of RNi5 (R = Y, La, Ce) paramagnetic intermetallic compounds. The dispersion measurements of the refractive index n and of the absorption coefficient k were conducted within a spectral interval 0.083–5.64 eV at room temperature. The behavior of optical interband conductivity with energy is analyzed. The results obtained are discussed in the frame of available information on the electronic band structure of these compounds. The plasma and relaxation frequencies of conduction electrons have been determined.  相似文献   

4.
The dispersion curves for crystal lattices of univalent mercury halides Hg2Hal2 (Hal=Cl, Br, I) are calculated from the experimental frequencies at singular points of the Brillouin zone and the velocities of sound in the framework of the valence-force field model. The results of calculating the dispersion branch of the TA soft mode along the Γ-X direction of the Brillouin zone and the calculated elastic moduli are presented. The calculated values are in good agreement with the experimental data.  相似文献   

5.
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   

6.
The magnetic phase transitions in RMn2O5 oxides were analyzed. It was shown that the transition from the paramagnetic phase to the incommensurate phase is described by not only the basic magnetic parameter but also an associated order parameter: electric polarization along the y axis of the crystal. It was established that the antiferromagnetic-incommensurate phase transformation is a second-order phase transition, accompanied by a decrease in electric polarization.  相似文献   

7.
The conditions and the mechanisms of crystallization by liquid-phase epitaxy of undoped and Ce3+-doped RAlO3 (R = Lu, Lu-Y, Y, Tb) single-crystalline films on YAlO3 single-crystalline substrates at a considerable mismatch between the lattice constants of the single-crystalline films and the substrate are analyzed. The maximum values of this mismatch at which the stable growth of the single-crystalline films is observed are determined. It is demonstrated that transition layers are present between the substrates and the grown single-crystalline films in which the difference between the lattice parameters of the single-crystalline film and the substrate is diminished. The optical and luminescence characteristics of the undoped and Ce3+-doped RAlO3 (R = Y, Y-Lu, Lu, Tb) single-crystalline films, as well as the scintillation characteristics of the (Lu-Y)AlO3: Ce single-crystalline films under excitation by alpha-particles of the 239Pu source (5.15 MeV), are investigated.  相似文献   

8.
Porous sulfur-doped In(OH)3 (In(OH) x S y ) hollow nanocubes were fabricated for the first time by taking advantage of a facile solution-phase approach using thioacetamide as the sulfur source at a temperature as low as 80 °C. The phase structures, composition, and morphologies of resulting products were investigated by powder X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, and high-resolution transmission electron microscopy. The characterization results indicated that the addition of thioacetamide in synthetic solution could not only accelerate the hollowing process and tune the size of nanocubes but also facilitate the doping of sulfur in In(OH)3. We proposed that the cooperative combination of oriented attachment and Ostwald ripening as well as chemical-etching process governed the crystal growth, resulting in the formation of the porous sulfur-doped In(OH)3 hollow nanocubes in this study. We also found these novel In(OH)3-based hollow nanostructures showed evolutional room temperature photolumincence emissions at visible-light region, suggesting their potential application in the optical and photocatalytic fields.  相似文献   

9.
The optical characteristics of nickel films deposited on Si(100) substrates by vacuum thermal evaporation have been studied. The thickness and optical constants of the films are determined using monochromatic zero ellipsometry, while the inverse problems are solved within the three-layer optical model of the samples. It is shown that thermal annealing leads to a change in the optical constants of nickel films in the heating-temperature range of 500–900°C. Boron carbonitride layers deposited on silicon substrates with a nickel sublayer are analyzed within multilayer optical models, which make it possible to determine the refractive index and absorption coefficient distributions along the thickness of the synthesized Si(100)/Ni/BC x N y structure.  相似文献   

10.
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   

11.
A second-order perturbation theory, developed for calculating the energy levels of the He-CO binary complex, is applied to small He N -CO clusters with N = 2−4, the helium atoms being considered as a single bound object. The interaction potential between the CO molecule and HeN is represented as a linear expansion in Legendre polynomials, in which the free rotation limit is chosen as the zero approximation and the angular dependence of the interaction is considered as a small perturbation. By fitting calculated rotational transitions to experimental values it was possible to determine the optimal parameters of the potential and to achieve good agreement (to within less than 1%) between calculated and experimental energy levels. As a result, the shape of the angular anisotropy of the interaction potential is obtained for various clusters. It turns out that the minimum of the potential energy is smoothly shifted from an angle between the axes of the CO molecule and the cluster of θ = 100° in He-CO to θ = 180° (the oxygen end) in He3-CO and He4-CO clusters. Under the assumption that the distribution of helium atoms with respect to the cluster axis is cylindrically symmetric, the structure of the cluster can be represented as a pyramid with the CO molecule at the vertex.  相似文献   

12.
Arrays of vertically aligned nitrogen-doped carbon (CN x ) nanotubes have been synthesized by decomposition of aerosol mixture of acetonitrile and ferrocene at 850°C. Nitrogen concentration in the outer shells of the CN x nanotubes was found from X-ray photoelectron spectroscopy (XPS) data to reach ∼6%. The XPS N 1s spectra and N 1s near-edge X-ray absorption fine structure (NEXAFS) spectra identified three chemical forms of nitrogen in the CN x nanotube arrays: pyridine-like, graphitic, and molecular nitrogen. The π * resonance of molecular nitrogen showed clear polarization dependence that indicates predominant orientation of N2 molecules along the nanotubes axis. The estimated range of the polar angle distribution of the N2 molecules orientation in the CN x nanotube array amounts to 15°.  相似文献   

13.
O. P. Yushchenko  V. F. Kurshetsov  A. P. Filin  S. A. Akimenko  A. V. Artamonov  A. M. Blik  V. V. Brekhovskikh  V. S. Burtovoy  S. V. Donskov  A. V. Inyakin  A. M. Gorin  G. V. Khaustov  S. A. Kholodenko  V. N. Kolosov  A. S. Konstantinov  V. M. Leontiev  V. A. Lishin  M. V. Medynsky  Yu. V. Mikhailov  V. F. Obraztsov  V. A. Polyakov  A. V. Popov  V. I. Romanovsky  V. I. Rykalin  A. S. Sadovsky  V. D. Samoilenko  V. K. Semenov  O. V. Stenyakin  O. G. Tchikilev  V. A. Uvarov  V. A. Duk  S. N. Filippov  E. N. Guschin  Yu. G. Kudenko  A. A. Khudyakov  V. I. Kravtsov  A. Yu. Polyarush  V. N. Bychkov  G. D. Kekelidze  V. M. Lysan  B. Zh. Zalikhanov 《JETP Letters》2018,107(3):139-142
Recent results from OKA setup concerning form factor studies in Ke3 decay are presented. About 5.25 M events obtained for decays of 17.7 GeV/cK+ are selected for the analysis. The linear and quadratic slopes for the decay form factor f+(t) are measured: λ'+ = 2.95 ± 0.022 ± 0.018 × 10 -2 for the linear slope fit and λ+ = 2.611 ± 0.035 ± 0.028 × 10 -2, λ"+ = 1.91 ± 0.19 ± 0.14 × 10 -3 for the quadratic one. The scalar and tensor contributions are compatible with zero. Several alternative parametrizations are tried: the Pole fit parameter is found to be M V = 891 ± 3 MeV; the parameter of the dispersive parametrization is measured to be Λ+ = 2.458 ± 0.018 × 10-2.  相似文献   

14.
The hydride phases of the intermetallic compounds GdNi3 and DyNi3 are synthesized at room temperature and at 273 K under a hydrogen pressure of 1–30 bar. The phase composition of the obtained samples is established using the X-ray diffraction method and the crystal-lattice parameters of the hydride phase are determined. The crystal phases are synthesized at room temperature under a hydrogen pressure of about 1 bar. At 273 K and under a pressure of 30 bar, amorphous samples are formed. The desorption of hydrogen from amorphous hydrides at 573 K leads to the formation of well-crystallized samples of the initial intermetallides. The amorphous samples are formed due to the ordering of hydrogen atoms in the metallic matrix of the hydride at low temperatures.  相似文献   

15.
Certain B s 0V 1 V 2 decays (V i is a vector meson) can be related by flavor SU(3) symmetry to corresponding B d 0V 3 V 4 decays. In this paper, we show that the final-state polarization can be predicted in the B s 0 decay, assuming polarization measurements of the B d 0 decay. This can be done within the scenario of penguin annihilation (PA), which has been suggested as an explanation of the unexpectedly large transverse polarization in Bφ K *. PA is used to estimate the breaking of flavor SU(3) symmetry in pairs of decays. Two of these for which PA makes a reasonably precise prediction of the size of SU(3) breaking are (B s 0φ φ,B d 0φ K 0*) and ( ). The polarization measurement in the B d 0 decay can be used to predict the transverse polarization in the B s 0 decay and will allow for testing of PA as well as the other assumptions in the analysis.  相似文献   

16.
The elastic moduli and elastic constants of the ternary semiconductor alloy Al y Ga1-yAs at finite temperature have been investigated using the statistical moment method. The Young, shear, bulk moduli and elastic constants C11, C12, C44 of the zinc-blende Al y Ga1?yAs crystal are calculated as functions of Al composition and temperature. Numerical calculations have been performed and compared with those of the experimental and other theoretical results showing the reasonable agreements. Our study shows that elastic moduli and C11, C12 constants of zinc-blende Al y Ga1?yAs alloy are decreasing functions of the temperature and Al composition; C44 constant is a decreasing function of the Al composition.  相似文献   

17.
The NMR spectra and the decay of a spin echo signal from 51V nuclei in Kagome-staircase Co3V2O8 (CVO) and Ni3V2O8 (NVO) single crystals are measured in the temperature range 30–300 K and a magnetic field H 0 = 20 kOe. The orientation dependences of the 51V NMR line shape are used to determine the electric field gradient (EFG) parameters, namely, quadrupole frequency ν Q and asymmetry parameter η. These parameters for NVO and CVO are ν Q = 180(10) kHz, η = 0.5(1) and ν Q = 130(10) kHz, η = 0.6(1), respectively. A comparison of the results of calculating EFG tensors with a point charge model and the NMR data indicates that the crystallographically equivalent vanadium atoms in the Ni3V2O8 and Co3V2O8 compounds differ in the EFG axis orientation. M3V2O8 crystals are found to have vanadium positions (V1, V2) with different orientations of the z axis, which specifies the direction of the principal value of EFG (V zz ): these orientations lie in the bc plane and make an angle of either +51(5)° (V1) or −51(5)° (V2) with axis c. In the temperature range 30–300 K, the EFG tensor components and the local symmetry of the charge surrounding of the vanadium positions in NVO and CVO oxides are found to change insignificantly.  相似文献   

18.
We have studied structural, thermodynamic, elastic, and electronic properties of cubic IrO2 polymorph via ab initio calculations within the LDA and GGA approximations. Basic physical properties, such as lattice constant, bulk modulus, second-order elastic constants (Cij), and the electronic band structures are calculated, and compared with available experimental values. We have, also, predicted the Young's modulus, Poison's ratio (ν), Anisotropy factor (A), sound velocities, and Debye temperature.  相似文献   

19.
The energies of formation of vacancies in the carbon and silicon sublattices, the independent elastic constants, the all-round compression, shear and Young’s moduli, and the anisotropy coefficients are determined for the complete and nonstoichiometric cubic phases of 3C-SixCy (x, y = 1.0–0.75) by ab initio methods of the band theory. In the formalism of the density functional perturbation theory (DFPT), the phonon dispersion dependences are obtained for these phases (the comparison with the experiment is given for the complete phase). It is shown that the mechanical characteristics of the phases become strongly anisotropic upon the transition from 3C-SiC0.875 to 3C-SiC0.75. It is established from the analysis of the phonon dispersion curves that the 3C-SiC0.875 and 3C-SiC0.75 phases, in contrast to the complete 3C-SiC phase, are dynamically unstable at T = 0 K.  相似文献   

20.
For a given crystal structure, say body-centred-cubic, the many-body Hamiltonian H in which nuclear and electron motions are to be treated from the outset on the same footing, has parameters, for the elements, which can be classified as (i) atomic mass M, (ii) atomic number Z, characterizing the external potential in which electrons move, and (iii) bcc lattice spacing, or equivalently one can utilize atomic volume, . Since the thermodynamic quantities can be determined from H, we conclude that T c , the superconducting transition temperature, when it is non-zero, may be formally expressed as T c = . One piece of evidence in support is that, in an atomic number vs. atomic volume graph, the superconducting elements lie in a well defined region. Two other relevant points are that (a) T c is related by BCS theory, though not simply, to the Debye temperature, which in turn is calculable from the elastic constants C 11, C 12, and C 44, the atomic weight and the atomic volume, and (b) T c for five bcc transition metals is linear in the Cauchy deviation C * = (C 12 - C 44 )/(C 12 + C 44 ). Finally, via elastic constants, mass density and atomic volume, a correlation between C * and the Debye temperature is established for the five bcc transition elements.Received: 13 May 2004, Published online: 23 July 2004PACS: 74.62.-c Transition temperature variations - 74.70.Ad Metals; alloys and binary compounds  相似文献   

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