共查询到20条相似文献,搜索用时 250 毫秒
1.
N. I. Kourov Yu. V. Knyazev E. V. Zenkov A. S. Moskvin 《Physics of the Solid State》2003,45(5):895-898
The optical properties of PdMnxFe1?x ternary alloys in the homogeneous ferromagnetic (F1, for x ~ 0) and antiferromagnetic (A, for x ~ 1) states, as well as in the microinhomogeneous state (at x=0.7), are discussed. In the x=0.7 alloy, the presence of nuclei of the low-resistivity, PdFe-type F1 phase in the high-resistivity, PdMn-type A matrix was shown to produce a narrow maximum on the optical-conductivity σ(ω) curve at E ~ 0.1 eV, which is due to a geometric resonance associated with light scattering from phase inhomogeneities of the sample. The behavior of σ(ω) in the interband transition region is dominated by parameters of the electronic spectrum of both the A and F1 phases. 相似文献
2.
The production of F- and M-centres in KCl by X-irradiation has been studied at temperatures between ?20 °C and 50 °C. The optical absorption measurements could be conducted without interrupting the X-irradiation. The results can be summarized as follows: 1. In Harshaw KCl crystals the number of F-centres created by the so-called fast coloration process was proportional to the height of the absorption band at 204 mμ prior to the irradiation. 2. The F-centres formed by the fast process did not contribute to the formation of M-centres. 3. In crystals with a strong absorption band at 204 mμ unstable M-centres were observed, which decayed rapidly after the cessation of the X-irradiation. Their concentration was found to be independent of the F-centre concentration. 4. At temperatures below 0 °C the relation between the concentration of the stable M-centres and the F-centre concentration could not any longer be represented by [M]=k 12·[F1]·[F2]+k 22·[F2]2, F1 and F2 referring to the F-centres created respectively by the fast and the slow coloration process. Except at very low F2-centre concentrations however the relationship [M]=k 0+k 2·[F2]2 represented the experimental data at all temperatures between ?20 °C and 50 °C. At constant temperaturek 2 varied withL, the X-ray energy absorbed per unit time and unit volume, according to 1/k 2=a+bL+cL 2. The temperature dependence ofa ?1 b ?1 andc ?1 could be approximated by Boltzmann factors. The corresponding activation energies wereE a=0.12 eV,E b=0.53 eV,E c=0.97 eV. 相似文献
3.
N. D. Potekhina N. R. Gall’ E. V. Rut’kov A. Ya. Tontegode 《Physics of the Solid State》2003,45(4):782-787
New measurements are performed and a comprehensive analysis of experimental data is made on the dependence of equilibrium carbon coverage θ on a tungsten surface on its temperature and the degree of carbon loading. It is shown that if the volume is free of carbon, the variation of θ for T≥1400 K can be approximately described by the balance between the carbon flows through the boundary with the activation energy for transition into the bulk E1=4.6 eV and the segregation energy ΔE=1.7 eV. For tungsten loaded preliminarily with carbon to a content of ≈10?2 at. %, the θ(T) relation cannot be described in terms of the equilibrium conditions with constant E1 and ΔE, because these quantities depend on the degree of carbon loading; E1 grows from 4.6 to 6.8 eV and ΔE grows from 1.7 to 2.3 eV with an increase in carbon content from 0 to 10?2 at. %. These variations are attributed to the bonds becoming stronger in carbon-loaded tungsten with increasing carbon content. 相似文献
4.
Dragos-Victor Anghel Sergiu Cojocaru 《The European Physical Journal B - Condensed Matter and Complex Systems》2017,90(12):260
We study the heat power P transferred between electrons and phonons in thin metallic films deposited on free-standing dielectric membranes. The temperature range is typically below 1 K, such that the wavelengths of the excited phonon modes in the system is large enough so that the picture of a quasi-two-dimensional phonon gas is applicable. Moreover, due to the quantization of the components of the electron wavevectors perpendicular to the metal film’s surface, the electrons spectrum forms also quasi two-dimensional sub-bands, as in a quantum well (QW). We describe in detail the contribution to the electron–phonon energy exchange of different electron scattering channels, as well as of different types of phonon modes. We find that heat flux oscillates strongly with thickness of the film d while having a much smoother variation with temperature (T e for the electrons temperature and T ph for the phonons temperature), so that one obtains a ridge-like landscape in the two coordinates, (d, T e ) or (d, T ph ), with crests and valleys aligned roughly parallel to the temperature axis. For the valley regions we find P ∝ T e 3.5 – T ph 3.5 . From valley to crest, P increases by more than one order of magnitude and on the crests P cannot be represented by a simple power law. The strong dependence of P on d is indicative of the formation of the QW state and can be useful in controlling the heat transfer between electrons and crystal lattice in nano-electronic devices. Nevertheless, due to the small value of the Fermi wavelength in metals, the surface imperfections of the metallic films can reduce the magnitude of the oscillations of P vs. d, so this effect might be easier to observe experimentally in doped semiconductors. 相似文献
5.
Quantum chemistry calculations of the intracrystalline potential relief in the nanolattice of LaF3 superionic crystal that contains 1200 ions and measures 3.5 × 2.0 × 2.2 nm along the x, y, and z axis, respectively, have been performed. Using the MOPAC 2012 program package, the potential relief profile has been simulated in the central part of the nanolattice for an elementary act of disordering in the lowest melting sublattice of F1 ions. It has been found that the height E m of barriers that prevent the motion of F1 in the dielectric phase of LaF3 crystal equals 0.37 eV and decreases to 0.15 eV in the superionic state. In addition, activation energy E a of F1 sublattice disordering in the dielectric and superionic states is equal to 0.16 and 0.04 eV, respectively. The profiles of the potential relief calculated on the xy and xz faces of the LaF3 3D nanolattice for the case when an F1 ion moves along the x crystal axis in the dielectric state are presented. The corresponding energy barriers are 1.5–2.0 times lower than those at the center of the LaF3 nanlattice. 相似文献
6.
Yu. G. Galitsyn D. V. Dmitriev V. G. Mansurov S. P. Moshchenko A. I. Toropov 《JETP Letters》2005,81(12):629-633
The critical exponents of the β-(2×4) → α-(2×4) reconstruction phase transition on the (001) GaAs surface are determined experimentally. It is found that the phase transition is analogous to a van der Waals transition. The critical parameters T c , P c , and Θc have been measured experimentally. The mean field theory is applied, and three-parameter isotherms are obtained that agree with the experimental results at the following values of the parameters: Est = 0.36 eV, ΔE = 0.18 eV, and E i = 0.134 eV. Precision measurements of the critical exponents β and δ are carried out. Their values β = 1/8 and δ = 15 indicate that the phase transition is truly two-dimensional. 相似文献
7.
General analytical expressions are obtained for the dynamical matrix D(k) and the elastic constants C ik in an HCP crystal in terms of the Born-von Karman (BvK) parameters. An analytical method is proposed for constructing D(k) on the basis of data about the phonon frequencies ω i (N) at the symmetry points of the Brillouin zone and the elastic constants C ik . A number of relations between the values of ω i (N) and C ik are presented for conventional interaction models. It is shown that the standard method for determining BvK parameters by fitting them to experimental phonon spectra in HCP lattices is, as a rule, ambiguous, whereas the analytical method proposed allows one to find all the solutions of the problem. The methods developed are illustrated by the construction of dynamical matrices for Tb, Sc, Ti, and Co. 相似文献
8.
A. S. Komolov E. F. Lazneva N. B. Gerasimova Yu. A. Panina A. V. Baramygin S. A. Pshenichnyuk 《Physics of the Solid State》2016,58(9):1901-1905
The results of the investigation of the electronic structure of the conduction band and the interfacial potential barrier during the formation of interfaces of dioctyl-substituted perylenedicarboximide (PTCDI-C8) and diphenyl-substituted perylenedicarboximide (PTCDI-Ph) ultrathin films with the oxidized germanium surface have been presented. The experimental results have been obtained using the very low energy electron diffraction (VLEED) technique in the total current spectroscopy (TCS) mode at energies in the range from 5 to 20 eV above the Fermi level EF. The positions of the maxima of the fine structure of total current spectra (FSTCS) of the PTCDI-C8 and PTCDI-Ph films differ significantly in the energy range from 9 to 20 eV above the Fermi level EF, which can be associated with the difference between the substituents of the chosen molecules, dioctyl- and diphenyl-, respectively. At the same time, the positions of the lowenergy maxima in the FSTCS spectra at an energy 6–7 eV above the Fermi level EF for the PTCDI-C8 and PTCDI-Ph films almost coincide with each other. It has been suggested that these maxima are attributed to the electronic states of the perylene core of the molecules under investigation. The process of the formation of interfacial potential barriers of the PTCDI-C8 and PTCDI-Ph films with the oxidized germanium surface has been analyzed. It has been found that the work functions of the surface, Evac–EF, differ little from 4.6 ± 0.1 eV over the entire range of organic coating thicknesses from 0 to 6 nm. 相似文献
9.
A. V. Golubkov L. S. Parfen’eva I. A. Smirnov H. Misiorek D. Wlosewicz J. Mucha A. Jezowski 《Physics of the Solid State》2008,50(1):1-5
This paper reports on the measurements of the thermal conductivity κ and electrical resistivity ρ in the temperature range 5–300 K and the heat capacity at constant pressure C p in the range 80–300 K for the metallic nonmagnetic compound LuMgCu4. The experimental values of κ and C p for the LuMgCu4 compound are compared with the corresponding data available in the literature for the light heavy-fermion compound YbMgCu4. It is shown that, in the low-temperature range (5–20 K), the phonon thermal conductivity κph of YbMgCu4 is lower than κph of LuMgCu4 as a result of phonon scattering from magnetic moment fluctuations of the Yb 4f electrons and, conversely, the heat capacity of LuMgCu4 in the range 80–300 K is lower than that of YbMgCu4 because the heat capacity of the latter compound has an additional magnetic component. 相似文献
10.
Let F : [0, ∞) → [0, ∞) be a strictly increasing C 2 function with F(0) = 0. We unify the concepts of F-harmonic maps, minimal hypersurfaces, maximal spacelike hypersurfaces, and Yang-Mills Fields, and introduce F-Yang-Mills fields, F-degree, F-lower degree, and generalized Yang-Mills-Born-Infeld fields (with the plus sign or with the minus sign) on manifolds. When \({F(t)=t, \frac 1p(2t)^{\frac p2}, \sqrt{1+2t} -1,}\) and \({1-\sqrt{1-2t},}\) the F-Yang-Mills field becomes an ordinary Yang-Mills field, p-Yang-Mills field, a generalized Yang-Mills-Born-Infeld field with the plus sign, and a generalized Yang-Mills-Born-Infeld field with the minus sign on a manifold respectively. We also introduce the E F,g ?energy functional (resp. F-Yang-Mills functional) and derive the first variational formula of the E F,g ?energy functional (resp. F-Yang-Mills functional) with applications. In a more general frame, we use a unified method to study the stress-energy tensors that arise from calculating the rate of change of various functionals when the metric of the domain or base manifold is changed. These stress-energy tensors are naturally linked to F-conservation laws and yield monotonicity formulae, via the coarea formula and comparison theorems in Riemannian geometry. Whereas a “microscopic” approach to some of these monotonicity formulae leads to celebrated blow-up techniques and regularity theory in geometric measure theory, a “macroscopic” version of these monotonicity inequalities enables us to derive some Liouville type results and vanishing theorems for p?forms with values in vector bundles, and to investigate constant Dirichlet boundary value problems for 1-forms. In particular, we obtain Liouville theorems for F?harmonic maps (which include harmonic maps, p-harmonic maps, exponentially harmonic maps, minimal graphs and maximal space-like hypersurfaces, etc.), F?Yang-Mills fields, extended Born-Infeld fields, and generalized Yang-Mills-Born-Infeld fields (with the plus sign and with the minus sign) on manifolds, etc. As another consequence, we obtain the unique constant solution of the constant Dirichlet boundary value problems on starlike domains for vector bundle-valued 1-forms satisfying an F-conservation law, generalizing and refining the work of Karcher and Wood on harmonic maps. We also obtain generalized Chern type results for constant mean curvature type equations for p?forms on \({\mathbb{R}^m}\) and on manifolds M with the global doubling property by a different approach. The case p = 0 and \({M=\mathbb{R}^m}\) is due to Chern. 相似文献
11.
Werner Mehlhorn 《Zeitschrift für Physik A Hadrons and Nuclei》1965,187(1):21-40
The Auger spectra of theM 2,M 3,M 4,M 5 subshells of krypton and the Coster-Kronig spectra of theM 1,M 2,M 3 subshells of krypton were measured with an electrostatical spectrometer. The ionization in theM shells was caused by electron impact. The use of a gaseous target made it possible to measure the Auger lines even at energies as low as 25 eV. The absolute energies and relative intensities of a great number of transitions were determined: 22 of theM 4, 5 spectrum, 14 of theM 2, 3 spectrum and 2 of theM 1 spectrum. Only in the case of theM 2, 3 spectrum a comparison between the relative intensities, determined experimentally, and those calculated byRubenstein forZ=47 was possible. The agreement is only qualitatively. Moreover, from the Auger electron energies measured, the following binding energies were calculated:E(M 1)=(292,1±1,0) eV,E(M 2)=(222,1±0,6) eV,E(M 3)=(214,6±0,6)eV,E(N 1 N 1)=(62,81±0,05) eV. 相似文献
12.
Samples of the composition TlNiS2 in the hexagonal system with the unit cell parameters a=12.28 Å, c=19.32 Å, and ρ=6.90 g/cm3 are synthesized. The results of the investigation into the electrical and thermoelectrical properties of TlNiS2 samples in the temperature range 80–300 K indicate that TlNiS2 is a p-type semiconductor. It is found that, at temperatures ranging from 110 to 240 K, TlNiS2 samples in a dc electric field possess variable-range-hopping conduction at the states localized in the vicinity of the Fermi level. The density of localized states near the Fermi level is determined to be NF=9×1020 eV?1 cm?3, and the scatter of the states is estimated as J≈2×10?2 eV. In the temperature range 80–110 K, TlNiS2 exhibits activationless hopping conduction. At low temperatures (80–240 K), the thermopower of TlNiS2 is adequately described by the relationship α(T)=A+BT, which is characteristic of the hopping mechanism of charge transfer. In the case when the temperature increases to the temperature of the onset of intrinsic conduction with the activation energy ΔE=1.0 eV, there arise majority intrinsic charge carriers of both signs. This leads to an increase in the electrical conductivity σ and, at the same time, to a drastic decrease in the thermopower α; in this case, the thermopower is virtually independent of the temperature. 相似文献
13.
A. P. Martynenko 《Physics of Atomic Nuclei》2008,71(1):125-135
Corrections of order α
5 and α
6 are calculated for muonic hydrogen in the fine-structure interval ΔE
fs = E(2P
3/2) − E(2P
1/2) and in the hyperfine structure of the 2P
1/2-and 2P
3/2-wave energy levels. The resulting values of ΔE
fs = 8352.08 μeV, ΔẼ
hfs(2P
1/2) = 7819.80 μeV, and ΔẼ
hfs(2P
3/2) = 3248.03 μeV provide reliable guidelines in performing a comparison with relevant experimental data and in more precisely
extracting the experimental value of the (2P–2S) Lamb shift in the muonic-hydrogen atom.
Original Russian Text ? A.P. Martynenko, 2008, published in Yadernaya Fizika, 2008, Vol. 71, No. 1, pp. 126–136. 相似文献
14.
B. D. Shanina N. N. Grigor’ev A. I. Klimovskaya T. I. Kamins 《Physics of the Solid State》2007,49(1):39-45
Full-electron calculations of the electronic structure of the TiSi2 compound in the structural modification C49 are performed using the augmented-plane-wave method. The total energy, the electronic band structure, and the density of states are calculated for an extended translational unit cell Ti4Si8, which is formed during the growth of a silicon nanowire on a p-Si substrate. Calculations are also carried out for two orthorhombic unit cells of the nonstoichiometric compositions Ti3Si9 and Ti5Si7. The energies of the interatomic bonds are determined to be E Si-Si = 1.8 eV, E Ti-Ti = 2.29 eV, and E Ti-Si = 4.47 eV. The dependence of the total energy of the unit cell E tot(V) on the unit cell volume V is obtained by optimizing the unit cell volume. The bulk modulus B 0 = 132 GPa is determined from the Murnaghan equation of state for solids and the dependence E tot (V). This value of the bulk modulus is used to estimate the activation energy for interstitial diffusion of silicon atoms Q i(Si) ≈ 0.8 eV. 相似文献
15.
I. Kudryavtseva A. Lushchik A. I. Nepomnyashchikh F. Savikhin E. Vasil’chenko Yu. Lisovskaya 《Physics of the Solid State》2008,50(9):1667-1670
A coordinated study of the relaxation of optical absorption induced by vacuum ultraviolet radiation, x-rays, and α-particles, as well as of photo- and thermostimulated luminescence (TSL) of LiF : Mg, Ti crystals (TLD-100) in the 295–750-K interval, has revealed that TSL regions characterized by activation energies E a = 2.2–2.4 eV and anomalously high frequency factors p 0 = 1021–1022 s?1 alternate with regions where E a = 1.5 eV and p 0 = 1012–1014 s?1. The relative intensities of the TSL peaks produced by UV illumination (10–17 eV) differ strongly under the conditions of selective photon-induced generation of anion excitons, free electrons and holes, or near-impurity electronic excitations. The latter are responsible for the high efficiency of tunneling radiative (involving titanium centers) or nonradiative (involving hydroxyl ions) recombination. The analysis of TSL peaks of LiF: Mg, Ti and LiF took into account two-step processes, namely, thermal dissociation of three-fluorine F 3 ? molecules and recombination of the products of their decay (V K and V F centers, H interstices). 相似文献
16.
W. Eckstein 《Zeitschrift für Physik A Hadrons and Nuclei》1967,203(1):59-65
SpinpolarizationP(Θ) of slow electrons elastically scattered by a solid Hg-target has been studied in a double-scattering experiment for electron energies between 300 eV and 900 eV. For the same energy range the angular dependence of the scattered intensity has been measured. Maximum degree of polarization found isP=?0.23±0.04 (E=900 eV,Θ=105°). 相似文献
17.
F2 color centers with a superhigh concentration (5000-cm–1 absorption coefficient at 450 nm) were formed by high-density electron beams in a layer of LiF crystals of micrometer thickness. The F2-centers excited by high-power nanosecond wide-band optical pulses (the “soft” pumping regime) efficiently amplified the laser radiation and showed high stability under these conditions. A low stability of F2-centers to laser radiation (the “hard” excitation regime) is explained by the dissociation of (F 2 + , F–) pairs induced by two-step ionization of F2-centers: (2hν > 4.5 eV) → F2 → (F2)* → F 2 + + e; F + e → F–; F 2 + + F– → 3F. 相似文献
18.
Results are presented that were obtained by analyzing arrival directions for cosmic rays recorded by the Yakutsk array between 1974 and 2001 in the energy range E0=1017.6–17.9 eV for zenith angles in the region θ≤53°. It is shown that their flux consists of two components—an isotropic (about 75%) and a cluster (about 25%) one—that are characterized by sharply different degrees of anisotropy. At E0=1017.7–17.8 eV, the observed showers are found to be strongly correlated with the Supergalaxy plane. 相似文献
19.
Gisbert zu Putlitz 《Zeitschrift für Physik A Hadrons and Nuclei》1963,175(5):543-552
In order to determine the electric quadrupole moment of Sr87 (I= 9/2) the hyperfine structure-splitting of the 5s5p 3 P 1-state of the SrI-spectra was investigated by optical double resonance. By detection of high frequency transitions (ΔF=±1,Δm F=0,±1) in an external magnetic fieldH 0≈0 one obtains the hyperfine structure separations asv F=11/2?F=9/2=1463·149 (6) Mc/sec andv F=9/2?F=7/2=1130·264 (6) Mc/sec. From these frequencies one calculates the magnetic hyperfine structure-splitting constantA=?260·084 (2) Mc/sec and the electric quadrupole interaction constantB=?35·658 (6) Mc/sec. B leads to an electric quadrupole moment ofQ(Sr87)=+0·36 (3)·10?24 cm2. 相似文献
20.
Yu. I. Golovin A. A. Dmitrievskii N. Yu. Suchkova M. V. Badylevich 《Physics of the Solid State》2005,47(7):1278-1281
Radiation-stimulated and postradiation changes in the microhardness of silicon single crystals exposed to irradiation with a low-intensity flux of β particles (I = 9 × 105 cm?2 s?1, W = 0.20 + 0.93 MeV) are studied. It is established that the inversion of the radiation-induced plastic effect occurs at a characteristic irradiation time τc = 75 min; i.e., irradiation of silicon single crystals for a time τ < τc leads to nonmonotonic reversible hardening, whereas nonmonotonic reversible softening is observed under irradiation for a time τ > τc. It is demonstrated that there exists a correlation between the nonmonotonic dependences of the microhardness and the concentration of electrically active defects at acceptor levels with energies E c ? 0.11 eV, E c ? 0.13 eV, and E c ? 0.18 eV on the irradiation time. 相似文献