bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermalized and Hot Interstitial Halogen Ions in Alkali Halides
Authors: Lushchik A. Ch. , Frorip A. G. 
Published: July 2007

AbstractThe efficiency of α, I pair creation at exciton decay is high at 4.2 K for KCl, KBr, and RbBr crystals for which H centers are oriented along 〈110〉. The efficiency of α, I pair creation by VUV‐irradiation at 4.2 K is extremely low for NaCl crystals for which H centers are oriented along 〈111〉. The process of mobile crowdion‐type interstitial halogen ion (I center) formation in KCl, KBr, RbCl, and RbBr (but not in NaCl) due to the tunneling recharge of primary F, H pairs is discussed. Such an I crowdion can shift by several interanion distances along [110] even at 4.2 K and, as a result, the system leaves the zone of spontaneous annihilation of α and I centers.
Inelastic Scattering of Low‐Energy Electrons by Electrons Localized in Surface Potential Wells
Authors: Strelniker Ya. M. , Zinets O. S. 
Published: July 2007

AbstractInelastic scattering of low‐energy electrons on the surface of a semi‐infinite crystal with excitation of electrons localized in a surface potential well is considered. The analytical expressions for the electron inelastic scattering cross‐section as a function of initial energy, incidence and scattering angles as well as potential well parameters are obtained. It is shown, that the peaks of the cross‐section angle dependence are determined by the energy spectrum of electrons localized in the potential well.
The Influence of Complex Luminescence Centres on the Luminescent Properties of CaS: Eu
Authors: Gruzintsev A. N. , Demishev S. V. , Nikiforova T. V. 
Published: July 2007

AbstractPhotoluminescence, cathodoluminescence, and excitation spectra of CaS: Eu phosphors with different activator concentrations (0.1 to 2 at%) are measured at 4.2, 80, and 300 K. Excitation and luminescence bands originating from the associate centres Eu‐VCa are observed in addition to those of a single Eu centre. Calculations by the method of linear combination of atomic orbitals (LCAO) allow to obtain a scheme of the electron terms of the associates which is in good agreement with the experiment.
Nonlinear Current—Voltage Characteristics of Ta2O5 and Nb2O5 Amorphous Oxides
Authors: Bryksin V. V. , Goltsev A. V. , Khanin S. D. , Novotelnova A. V. , Vasilev A. N. 
Published: July 2007

AbstractNonlinear current‐voltage characteristics of Ta2O5 and Nb2O5 amorphous oxides are studied in the temperature range from 213 to 363 K. The data give an evidence for the polaron mechanism of charge transport in these materials. A theoretical treatment of data is presented that gives a critical hopping lenght and a critical index.
Concentrated Kondo Systems in Solid Solutions on the Base of Europium Ternary Compounds
Authors: Levin E. M. , Kuzhel B. S. , Bodak O. I. , Belan B. D. , Stets I. N. 
Published: July 2007

AbstractThe experimental results of the components substitution effect on crystal structure, electronic transport properties, and Eu effective valence in solid solutions based on EuCu2Si2 and EuPd2Si2 ternary compounds are presented. It is shown, that when the Eu effective valence reaches the critical value v = 2.1, corresponding to degeneration of the 4f7 and 4f6 configurations, the condition of the concentrated Kondo system and an essential perturbation of the band electron spectrum near the Fermi level occur.
Exact Relations and Galvanomagnetic Properties of the Inhomogeneous Two‐Dimensional Medium
Authors: Arkhincheev V. E. 
Published: July 2007

AbstractA two‐dimensional randomly inhomogeneous two‐composite medium in a magnetic field is considered. The exact relations for the effective characteristics of the system are found. The linear isomorphism between the galvanomagnetic and the conductivity problem is established. On the basis of these results the galvanomagnetic properties are studied.
An ESR Study of Li+ Impurity Ion Deformational Fields in KTaO3
Authors: Pechonyi A. P. , Antimirova T. V. , Glinchuk M. D. , Smolyaninov I. M. 
Published: July 2007

AbstractFrom a study of the influence of uniaxial pressure on the ESR spectrum of “cubic” paramagnetic Fe3+ centres in KTaO3, their spin—phonon coefficients G11 = 1.28 × 10−3 eV and G44 ⪅ 0.74 × 10−4 eV are determined. The dilatation part of the deformation tensor Ω1 = 1.4 eV of the Li+ off‐centre ion in KTaO3 is obtained as a result of the study of the elastic broadening of the ESR line caused by the deformation fields of the Li+ ions. It is shown that the deformation mechanism makes a substantial contribution to the ESR linewidth of these centres in K1−xLixTaO3.
A Study of the White Lines Associated with the Rare Earth LII and LIII Absorption Discontinuities in Some Oxides and Tungstates
Authors: Vishnoi A. D. , Sapre V. B. , Mande C. 
Published: July 2007

AbstractThe intensities are studied of the white lines associated with the LII and LIII absorption discontinuities of the rare earth elements in their oxides RE2O3 (RE = La, Ce, Pr, Nd, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu) and some tungstates RE2(WO4)3 (RE = La, Ce, Nd, Sm, Gd and Dy). These white lines correspond to the absorption transitions from the 2p1/2 to the 5d3/2 and from the 2p3/2 to the 5d5/2 levels. It is observed that the intensities of the white lines depend upon the filling of the 4f levels, which partially overlap the 5d levels.
Structural Modelling of Low‐Symmetry Phases of Spinels. I. Phases with 1:1 Octahedral Order
Authors: Talanov V. M. 
Published: July 2007

AbstractThe structural ordering mechanism of cations in octahedral positions of spinels of the type 1:1 is discussed using group‐theoretical methods of phase transition research. The structure of ordered phases is deduced theoretically from that of disordered phase. Qualitative pictures of possible displacements of atoms near phase transition temperatures are given. The experimental data are discussed.
Mean Square Displacement (MSD) of Neighbours around a Vacancy in Some Zinc Based Tellurides
Authors: Madhavan Y. , Ponnammal K. , Ramachandran K. , Haridasan T. M. 
Published: July 2007

AbstractThe mean square displacements (MSD) of neighbours around anion and cation vacancies in the systems ZnTe, ZnxCd1−xTe, and ZnxHg1−xTe are worked out for different values of x giving an active role for the vacancy following the theory of Maradudin et al. The results are compared with available experimental values and discussed.
Envelope Equation and Wave Function Matching for Narrow‐Gap Semiconductors
Authors: Paasch G. , Nguyen P. H. , Gobsch G. 
Published: July 2007

AbstractIt is shown that Zawadzki's equation for the conduction band envelope in a narrow‐gap semiconductor can be derived from the Ben Daniel‐Duke equation containing a position dependent effective mass if the position dependence of the band edge is taken into account in the Kane type energy dependence of the effective mass. Contrary to the original derivation of Zawadzki generalizations to other types of band structures are easily possible. As examples envelope equations are derived for an anisotropic Kane band structure and for the case of different conduction and valence band masses. In addition, the procedure presented here leads also to the conclusion that the envelope matching condition used till now has to be replaced by a more general and energy dependent one.
Optimization of Spin‐Hamiltonian Parameters by the Method of Non‐Linear Least‐Squares Fitting
Authors: Hrabański R. , Lech J. 
Published: July 2007

AbstractA non‐linear iterative least‐squares fitting procedure for the analysis of EPR spectra is presented. In this method the line positions obtained for a given orientation of the external magnetic field are fitted to evaluate the spin‐Hamiltonian parameters. The procedure is illustrated by an application to the X‐band room temperature EPR data obtained for Mn2+ doped single crystals of [Mg(H2O)6]SnCl6.
Investigation of the Thermodynamic Properties of Anharmonic Crystals by Momentum Method. IV. The Limiting of Absolute Stability and the Melting Temperature of Crystals
Authors: Tang Nguyen , Van Hung Vu 
Published: July 2007

AbstractOn the basis of results obtained earlier the equation for the limiting of absolute stability in the crystalline state with f.c.c. structure is found. Using this the limiting temperatures of absolute stability and the melting temperatures of inert gas crystals at various pressures (including of very high pressures) are determined. Besides, the nearest neighbour distances and the Grüneisen constants at these temperatures are obtained. In comparison with the experimental data the calculated results deviate only by some per cent.
Lattice Dynamics of Sulphur Dioxide
Authors: Binbrek O. S. , Anderson A. 
Published: July 2007

AbstractA simple force constant model is developed and applied to the vibrations of solid sulphur dioxide. Eight parameters (two intra‐ and six inter‐molecular force constants) are adjusted to obtain the best fit to the 15 lattice and internal mode frequencies observed by Raman and infrared spectroscopy. The calculated eigenvectors are used to assign the frequencies and to estimate the degree of translationallibrational mixing.
Potential Energy of an Argon Atom Adsorbed on the Stepped and Kinked Surfaces of a Sodium Chloride Crystal
Authors: Yanagihara T. , Yomogita K. 
Published: July 2007

AbstractThe potential energies of an Ar atom adsorbed on flat, stepped, and kinked NaCl crystal surfaces are calculated by using dispersion, electrostatic, and Born‐Mayer repulsive potentials. They have a minimum value (−10.1 kJ/mol) above each Na+ ion site in the flat surface and a minimum (−15.0 kJ/mol) in the vicinity of each Na+ ion site on the lower terrace along a step in the stepped surface. In the kinked surface they have a minimum value (−21.9 kJ/mol) in the vicinity of a kink on the lower terrace. Furthermore, on those sites the isosteric heats of an Ar adatom at zero coverage are calculated and discussed in comparison with experimental results.
Structural Classification of AB‐Type Binary Compounds
Authors: Walzer U. 
Published: July 2007

AbstractAt first, a review is given on how structure maps for the prediction of the space group and structure type of AB‐type binary compounds can be designed with the help of semiempirical theories. Then, two ab‐initio pseudopotential theories are compared in detail. The all‐electron single‐particle equation and the spin‐density‐functional formalism form the starting point for both theories. While transferability is aimed at in both theories, the conditions imposed differ in some respects. Theory A uses the Schrödinger equation as starting point. The crossing points of a screened pseudopotential are employed as characteristic quantities. The structure energy is dominated by s‐p electrons, even in the case of the compounds of two transition metals. Theory B is based on the Dirac equations and takes into account spin–orbit effects which are relevant for heavier elements. The coordinates of the minima of the bare‐ion potentials serve as characteristic radii and energies. In both cases, a good separation of the structure types is achieved. For theory B, in addition, a few predictions concerning lattice constant a and the melting temperature are represented graphically.
Low Temperature Specific Heats of AgSb Alloys
Authors: Al‐Shibani K. M. , Sacli O. A. 
Published: July 2007

AbstractLow temperature specific heats of AgSb alloys of concentrations 0.89; 2.67; 3.7, and 4.72 at% are measured between 0.4 and 4.2 K. Experimental results for pure Ag and AgSb alloys obey the relation C=γT + βT3 with an experimental error of 2%. It is observed that the electronic specific heat coefficient, γ, increases linearly with the impurity concentration while the Debye temperature, θD, decreases linearly with the concentration. It is established that the change of γ on alloying can be expressed as Δγ=1/3 c(Z – 1) by modifying the free electron result. Variation of the Debye temperature, θD, is believed to result from the change of mechanical properties of Ag. By employing Lindeman's melting theory it is shown that (θD)alloy=(1 – 0.63c) (θD)Ag which agrees satisfactorily with the experimental results.
Luminescent Associates of Pb2+vc− Dipoles with Interstitial Iodine Atoms in KI:PbI2 Crystals
Authors: Egemberdiev Zh. , Ismailov K. , Usarov A. , Zazubovich S. , Jaanson N. 
Published: July 2007

AbstractTwo infrared emission regions (with maxima at 0.803 and 0.723 eV) recently observed by Harami et al. in X‐irradiated KI:PbI2 and the emission regions with maxima at 2.01, 1.79, and near 1.2 eV are studied. The observed emission bands are connected with Hz(Pb2+) centres (Pb2+ ions associated to [I2−]ac molecular ions on anionic (a) and cationic (c) sites). The infrared emission bands of these centres are due to processes occuring in the excited state of the [I2−]ac molecular ion perturbed by the Pb2+ ion. The emission bands are connected with electronic transitions from the tetragonal (2.01 and 1.79 eV peaks) and trigonal (region around 1.2 eV) minima of the triplet relaxed excited state of the Pb2+ ions perturbed by the [I2−]ac ion which can occupy two different positions with respect to Pb2+. The emission band with maximum at 2.05 eV and the region near 1.2 eV are associated to similar transitions in the Pb2+ ion perturbed by the [I3−]aca (V2z(Pb2+) centres) molecular ion. On the basis of these results the optical properties of VL centres (at 0.805 and 0.734 eV), previously observed by Harami et al. in halogen‐excess KI crystals, and assumed here to be the [I2−]ac molecular ions, are also discussed.
On the Quasichemical Model of Oxygen Absorption and Ordering in a High Temperature Superconductor YBa2Cu3O6+x
Authors: Andreev L. A. , Nechaev Yu. S. , Kalashnikova E. A. , Konovalov N. T. , Lykhin V. A. , Mineav Yu. A. , Olshevskii N. A. 
Published: July 2007

AbstractIn the framework of the quasichemical Williams‐Bragg model an equation is obtained for the isotherm of gas absorption by the interstitials of the solvent lattice with the effect of ordering recognized; the equation is applied to analysis and interpretation of experimental data on oxygen absorption and ordering in superconducting YBa2Cu3O6+x ceramics. The oxygen absorption in both, tetragonal and orthorhombic structures is described by an absorption isotherm which fits the Langmuir equation. Extreme concentratios of the “absorption centers” are found as the oxygen absorption energy and entropy in the tetragonal (T) and orthorhomic (O) phases. The ordering of absorbed oxygen is shown to be unrelated with the “oxygenoxygen” pairwise interaction and is attributable to the “T → O” transition. The experimental isotherms of oxygen absorption by the ceramics lead to elements of the “temperature–concentration (X)” phase diagram which characterize the boundary between the T‐ and O‐phase regions.
Low Temperature Absorption Spectrum of LiNiPO4
Authors: Belletti A. , Borromei R. , Cammi R. , Cavalli E. 
Published: July 2007

AbstractThe polarized absorption spectrum of LiNiPO4 crystals is investigated in the range 5000 to 25000 cm−1 at 9 K. The splitting and intensities of the bands in different polarizations are interpreted mainly in terms of a C2v perturbation of the octahedral site. The energies of the transitions are reproduced by means of a ligand field calculation, in which only a Oh → C2v site perturbation is considered, assumed as preponderant in the symmetry descent Oh → C2v → Cs.
Model Dielectric Constants of InSb
Authors: Miyazaki T. , Adachi S. 
Published: July 2007

AbstractA calculation of the real (ϵ1) and imaginary (ϵ2) parts of the dielectric function of InSb between 0.0 and 6.0 eV in the temperature range 100 to 650 K is presented. This model includes the E0, E0 + Δ0, E1, E1 + Δ1, E'0, E'0 + Δ'0, E2 and E'1 gaps as the main dispersion mechanisms. The model is also made to account for the excitonic effects at the E1 and E1 + Δ1 critical points (CP's). The lineshape of the optical spectra obtained from this model is in satisfactory agreement with the experimental data over the entire range of photon energies. The temperature dependence of the strength and the broadening parameter at each CP are also given and discussed.
Tunneling‐Assisted Photon Emission in MIM Junctions
Authors: Volkov R. A. , Chuiko A. F. 
Published: July 2007

AbstractAnalytical expressions for the intensity of light emission associated with the inelastic tunneling of electrons in sandwich structures are obtained for semiclassical and quantum‐mechanical descriptions of the electron gas in electrodes. It is shown that in the quantum case the light intensity and currents of elastically tunneling electrons depend on the longitudinal density of electron states in the cathode and anode. Consideration is given to MIM junctions with crystallogrphically oriented electrodes exhibiting density peaks of free and occupied states near the Fermi levels. To increase the spectral intensity of the tunneling‐assisted photon emission in MIM junctions, it is proposed to use the electrodes made of such transition metals as Ni, Co, Mn, Ti, Fe, as well as of Pt and β‐NiAl which possess the above features.
Thermal Properties of TmGa3
Authors: Czopnik A. , Mädge H. , Pott R. 
Published: July 2007

AbstractHeat capacity and thermal expansion of TmGa3 single crystal are reported. At low temperatures in comparison to TN the heat capacity and thermal expansion coefficient have a T3 exp (– Δ/T) dependence with an energy gap Δ in the spin‐wave spectrum equal to 1.15 K. In the paramagnetic state the crystal‐field contribution to the thrmal properties of TmGa3 is analysed.
Eigenproblem of Standing Spin Waves in a Multilayer Film with Inhomogeneous Interlayers
Authors: Maciejewski W. 
Published: July 2007

AbstractA difference equation approach to standing spin waves in a multilayer film with inhomogeneous interlayers is developed. An exact procedure of solving the eigenvalue problem of dynamical matrix by its formal reduction to a small set of linear homogeneous equations is proposed. The effective parameters suitable for the study of the spin wave spectra and the spatial behaviour of the spin wave modes are introduced.
Raman Spectroscopic Study of Amorphous Pb5Ge3O11 and Its Crystallization
Authors: Lan Guo‐Xiang , Sun Hong‐Ye , Yin Zhi‐Ying , Wang Jing‐Yin , Wang Hua‐Fu 
Published: July 2007

AbstractAmorphous Pb5Ge3O11 is prepared by single‐roller quenching. Internal vibrational modes of the GeO tetrahedra (and the Ge2O double‐tetrahedra) are observed in the Raman spectrum from amorphous Pb5Ge3O11. The Raman spectra of the sample annealed at 410 °C are different from that annealed at higher temperature. The results confirm the existence of a metastable phase in the crystallization process of amorphous Pb5Ge3O11. The Raman frequencies of stable crystalline Pb5Ge3O11 decrease with increasing annealing temperature, and this is attributed to the stress induced during crystallization.
Backscattering of Fast Electrons
Authors: Afanasev V. P. , Naujoks D. 
Published: July 2007

AbstractThe inelastic reflection of fast electrons is investigated on the base of the “invariant imbedding method”. The non‐linear term in the integral equation can be neglected owing to the strong anisotropy of elastic cross‐section of fast electrons. Using the Fokker‐Planck approximation and the Laplace transformation a simple analytical formula is found expanding the backscattering coefficient into a series of Legendre polynomials. It is shown that the results from the model are in good quantitative agreement with experimental data.
Special Features of Optical Properties of Ternary Alloys Ti(FexCo1−x)
Authors: Sasovskaya I. I. 
Published: July 2007

AbstractMeasurements are made of the optical characteristics: n, k, σ(ω), ϵ1 (ω), ϵ2 (ω) of the ternary pseudo‐binary alloys Ti(FexCo1‐x), 0.2 ≦ x ≦ 0.8 in the spectral range 0.07 to 4.96 eV. The results obtained are compared with the optical properties of the compounds TiFe and TiCo. It is shown that the change in the main absorption band (0.6 ≦ ħω ≦ 3 eV) over the series of alloys can be explained by the shift of EF relative to the special features (minima, peaks) of the density of states curves N(E). An additional low‐energy quantum absorption within 0.2 ≤ ħω ≤ 0.6 eV discovered in ternary alloys is explained by interband transitions between virtual bound states which are due to antistructural Fe atoms and are responsible for ferromagnetism in Ti(FexCo1−x).
Molecular dynamics of the frozen‐in glassy state of Ni80P20
Authors: Stepanyuk V. S. , Katsnelson A. A. , Szasz A. , Trushin O. S. , Nayak P. 
Published: July 2007

AbstractA molecular dynamics approach is used for the dynamic structure simulation of the Ni80P20 glassy‐like system. Calculations are made considering the rapid cooling from melt and the effect of glass transition temperature. Comparison with the experimental data is given with a reasonable correspondence.
Self‐consistent statistical theory of surface properties of anharmonic crystals. I. Structural and dynamical properties of singular surfaces of F.C.C. crystals
Authors: Zubov V. I. , Tretyakov N. P. 
Published: July 2007

AbstractA statistical theory of anharmonic crystal—vapour interfaces is developed based on the correlative unsymmetrized self‐consistent field method (CUSF). The nonlinear integral equations for the one‐particle probability densities of atomes near the solid surface and their self‐consistent potentials are transformed into the transcendental equations for the moments of the distributions. Their solution determines the lattice relaxation near the surface, the amplitudes of the anharmonic vibrations of atoms, their anisotropy, and the self‐consistent potentials as well. As an application the structural and dynamical properties of an f.c.c. crystal in which the nearest neighbours interact are studied.
Vacancy motion in magnesium oxide analyzed via the CNDO/2 cluster model
Authors: Skala L. , Kenkre V. M. , Weiser M. W. , Katz J. D. 
Published: July 2007

AbstractThe dynamics of vacancies in magnesium oxide are studied applying the CNDO/2 method to calculate the electronic properties of clusters both, with and without magnesium and oxygen vacancies. The potentials for vacancy motion are calculated and detailed information about the character of bonding in the neighbourhood of a vacancy is obtained. It is found that the potential for magnesium ion migration is more squared‐off than the potential for oxygen ion migration. The shape of the potential well is expected to have practical relevance in microwave‐driven ionic diffusion.
An evaluation of the R—T spin coupling parameter in the rare earth–transition metal intermetallics
Authors: Duc Nguyen Huu 
Published: July 2007

AbstractFor the purpose of the evaluation of the R—T spin coupling parameter, ART, an analysis of the Curie temperature is made for the rare earth—transition metal systems RmTn (R rare earth T = Fe, Co; m/n = 1/2, 1/3, 6/23, and 2/17) and some systems of recent and growing interest, such as R2T14B, RT11Ti, RT10V2 and their ternaries Rm(Co, Fe)n. Besides the enhancement of ART in the light rare earth compounds, the dependence of ART on the magnetic moment of the 3d electrons is presented.
Interband electronic Raman scattering in semiconductors induced by nonparabolicity
Authors: Ismailov T. G. , Nazanly R. A. 
Published: July 2007

AbstractThe interband electronic Raman scattering (IERS) of light in narrow‐gap semiconductors due to nonparabolicity is investigated in the framework of the two‐band Kane model. Bulk and size‐quantized thin film cases are considered in detail. The possibilities to determine the semiconductor parameters and also to investigate the semiconductor—semimetal (and vice‐versa) transition with the aid of IERS are discussed.