bluuebunny/crossref_metadata_2025_split huggingface dataset:
Kronig‐Penney‐Type Calculations for Electron Tunneling through Thin Dielectric Films
Authors: Schnupp P. 
Published: July 2007

AbstractUsing a Kronig‐Penney model and matrix methods the probability D = exp ( − 2 χ a) of an electron tunneling through a thin dielectric film can be calculated exactly for an arbitrary value of the thickness a. The relation between the damping constant χ and the electron energy E in the band gap of the dielectric depends on the thickness a. For thick films containing more than 10 to 15 crystal planes the E(χ2)‐curves approximate to the usual ones obtained from band theory. However, the simple model involving potential walls without any potential wells is the limiting case for very thin films. Nevertheless, the departure of the complex band structure of the dielectric from the free electron‐approximation usually used in tunneling calculations should be observable qualitatively even for very thin films.
Microprobe Investigations of Copper Precipitates in Silicon Single Crystals
Authors: Fiermans L. , Vennik J. 
Published: July 2007

AbstractMicroprobe investigations of copper precipitates in silicon single crystals, confirm and extend the geometrical analysis performed by means of infra‐red microscopy. Evidence is obtained which proves that the concentration of carbon or oxygen is enhanced at the centres of the precipitates. This is in agreement with the proposed mechanism for the nucleation and growth of the copper precipitates i.e. indentation at SiO2 or SiC centres. Some effects concerning surface contamination are also examined.
Thermal Expansion and Compressibility of Solid Neon and Xenon
Authors: Gupta N. P. , Dayal B. 
Published: July 2007

AbstractThe lattice constants and isothermal compressibility of solidified neon and xenon are calculated at various temperatures for the harmonic approximation. An (exp, 6) potential function is used and zero‐point energy is included in the same way as in earlier papers. The theoretical and observed values of lattice constants and compressibility agree reasonably well for xenon but not so well for neon. It is suggested that the interaction in neon is somewhat analogous to that in helium, and the usual potentials which are applicable to heavy rare gas solids i.e. argon, krypton and xenon, are not suitable for neon.
Über die Messung der Anisotropie der galvanomagnetischen Transversalspannung an Einkristallfolien
Authors: Lück R. , Saeger K. E. 
Published: July 2007

AbstractDie Grundlagen der Meßmethode werden theoretisch begründet, und die Anwendbarkeit wird abgegrenzt. Über Meßergebnisse eines zusätzlich zum Halleffekt auftretenden Nebeneffektes (transverse‐even voltage) an Kupfereinkristallen wird berichtet. Die Messungen wurden bei 4,2 °K in Abhängigkeit von Orientierung und magnetischer Feldstärke durchgeführt. Mit Hilfe einer neuen allgemeingültigen Beziehung zwischen diesem Effekt und dem Widerstand im Magnetfeld, die auch den sättigenden Anteil des Widerstandes berücksichtigt, wird der Winkel zwischen Stromrichtung und Richtung der offenen Bahnen berechnet und die Übereinstimmung mit röntgenographisch gewonnenen Werten überprüft. Die Feldabhängigkeit dieses Effektes wird benutzt, den Widerstand im Magnetfeld in einen sättigenden und einen mit der magnetischen Feldstärke quadratisch ansteigenden Anteil zu zerlegen.
Infrared Fluorescence in Manganese Activated Zinc Sulphide Phosphors
Authors: Agrawal J. P. 
Published: July 2007

AbstractA luminescence emission in the 3.00 μm region is reported for manganese activated zinc sulphide phosphors where the manganese concentration is greater than 2%. Optical absorption measurements show a maximum at 0.80 μm with sub‐bands at 0.74 and 0.84 μm, the luminescence being excited by radiation in this region. It is suggested that a new luminescence centre is formed as a result of Mn2+ ions perturbing the host‐lattice.
Oszillationen der Oberflächenimpedanz von Wolfram in schwachen Magnetfeldern
Authors: Herrmann R. 
Published: July 2007

AbstractIn Magnetfeldern von 1 bis 150 Oe werden Oszillationen der Oberflächenimpedanz von Wolfram bei einer Frequenz des elektromagnetischen Feldes von 9,38 GHz in den kristallographischen Ebenen (10) und (001) bei einer Temperatur von 1,6 °K beobachtet.
A Comparison of Electron Microscope Images of Dislocations Based on Isotropic and Anisotropic Elasticity Theory
Authors: Humble P. 
Published: July 2007

AbstractA comparison is made between the electron diffraction images of dislocations computed on the basis of isotropic and anisotropic elasticity. It has been shown previously that for highly anisotropic materials, such as β‐brass, considerable contrast is obtained in the case of screw dislocations for which g · b = 0 and in the case of edge dislocations for which g · b = 0 and g · b × u = 0. The present calculations indicate that under these conditions some contrast would also be expected for dislocations in materials such as iron, niobium, copper and gold, which are considerably less anisotropic then β‐brass, providing the dislocations do not lie normal to an elastic symmetry plane. However, in most cases for which g · b ≠ 0, the approximation of isotropic elasticity is an adequate basis on which to deduce the character of the electron diffraction images of dislocations, even in highly anisotropic materials.
The Influence of the Size Effect on Electrical Resistivity Measurements in Irradiated Metals
Authors: Dworschak F. , Schuster H. , Wollenberger H. , Wurm J. 
Published: July 2007

AbstractTwo high purity Al foils of thickness 40 μm and 5.6 μm are simultaneously irradiated. The initial resistivity increments per unit defect concentration for the foils differ by a factor of two due to the size effect. Sondheimer's theory is in good agreement with the experimental data. The calculations are presented for a range of parameters so that the magnitude of this effect can be estimated for other experiments.
Peculiarities of the Magnetoresistance in Bi in High Transverse and Longitudinal Magnetic Fields
Authors: Bogod Yu. A. , Eremenko V. V. 
Published: July 2007

AbstractResults are presented of experimental studies of magnetoresistance of oriented Bi single crystals in pulsed transverse and longitudinal magnetic fields up to 90 and 160 kOe, respectively, at 4.2, 20.4, and 77 °K. The changes of the magnetic field dependence of the resistance observed previously [5] i.e. the tendency towards saturation, are studied in detail. Magnetoresistance anomalies are shown to appear in transverse and longitudinal magnetic fields at similar field strengths. An attempt is made to relate the results to the occurrence of open paths in high magnetic fields.
On the Low‐Temperature Internal Friction in Silicon
Authors: Kromer P. F. , Khiznichenko L. P. 
Published: July 2007

AbstractThe internal‐friction relaxation peak observed in silicon single crystals [6, 7] is discussed using Brailsford's concept of “built‐in” kinks on dislocations. The numerical estimates of the theory agree satisfactorily with the experimental data. The correlation of two theories based on thermally generated and “built‐in” kinks is also considered.
Mössbauer Effect in FeF3
Authors: Bertelsen U. , Knudsen J. M. , Krogh H. 
Published: July 2007

AbstractThe antiferromagnetic compount FeF3 is studied by the Mössbauer technique in the temperature range from 300 to 400 °K. A Néel temperature TN of (362.4 ± 0.2) °K is deduced from the data. If the reduced hyperfine field is represented by h(T) = D (1 − T/TN)β, it is found that β = 0.358 ± 0.013 in the region 0.81 < T/TN < 0.99. The shapes of the peaks in the Mössbauer spectra in the vicinity of the Néel temperature are discussed.
F‐Centers in SrF2
Authors: den Hartog H. W. , Arends J. 
Published: July 2007

AbstractResults are presented of ESR experiments and optical measurements on F‐centers in additively colored SrF2 crystals. The hyperfine interactions between the unpaired electron and the surrounding nuclei are discussed and compared with the results obtained for F‐centers in CaF2 and BaF2. Combined results of ESR experiments, optical measurements, and bleaching experiments indicate that the absorption band at 4490 Å arises from an electron trapped in an F− vacancy. It appears that there is no correlation between the absorption bands at 4490 and 6350 Å.
Thermotransport and the Associated Isotope Effect in Solids
Authors: Lodding A. 
Published: July 2007

AbstractIf the same mechanisms governs self‐diffusion, electrotransport, and thermotransport, then the kinetic energy distribution factor of diffusion. ΔK, can be measured directly by isotope transport techniques (electro‐ or thermotransport), in solid metals as well as ionic salts. Under these conditions the results of the isotope thermal diffusion experiments can be interpreted in terms of activation energy parameters. However, in the only two solids in which isotope thermotransport has been measured so far, cubic Li2SO4 and Li metal, these simple conditions probably do not apply.
Low Temperature Internal Friction of Aluminum at 1 Hz
Authors: Routbort J. L. , Sack H. S. 
Published: July 2007

AbstractThe internal friction and shear modulus of single and polycrystals of Al were measured of 1 Hz from 4.2 to 300 °K as a function of the amount of deformation, temperature at deformation, and gamma irradiation. Two Bordoni peaks were found with activation energies of (0.16 ± 0.01)eV and (0.26 ± 0.03) eV, and attempt frequencies of 5 × 10(12 ± 0.6)s−1 and 3 × 10(14 ± 1.3) s−1, respectively. The low temperature peak has a single attempt frequency, but a distribution of activation energies, while the process contributing to the other peak involves a distribution of attempt frequencies, and possibly a single activation energy. Gamma irradiation at low temperature does not effect these peaks. The relaxation strengths of the processes are a function of temperature. The annealing behavior of the Bordoni and other peaks found after low temperature deformation was also studied.
Plasmon Satellites of Soft X‐Ray Spectra
Authors: Brouers F. 
Published: July 2007

AbstractA theory of the intensity and shape of plasmon satellite bands in the soft X‐ray emission spectra of aluminium, magnesium and sodium is proposed. Based on the Bohm and Pines semi‐quantitative treatment of the electron gas, this theory is able to account very satisfactorily for the experimental data and provides a physical interpretation of the phenomenon. Because the electron undergoing the transition and the localized vacancy have opposite charges, their plasmon eigenfields partially cancel one another when the X‐ray transition occurs. This interference effect is not total because of the slight difference between the two plasmon field frequencies which arises from the relative motion of the vacancy and electron. This explains the occurrence and the weak intensity of the plasmon emission. The dispersion of the plasmon frequency provides an explanation of the profile of the plasmon satellites. Similar effects must occur when the electron‐positron annihilation in a metal is accompanied by the emission of a real plasmon.
Theory of Plasmon Excitation in Thin Films by Electrons of Non‐Normal Incidence
Authors: Otto A. 
Published: July 2007

AbstractCalculations of characteristic energy losses of electrons in thin dielectric foils are given for a) electrons with inclined incidence to the foil, b) electrons travelling parallel to the foil surface. Retardation is taken into account for case b) in the limit of very thick foils. For the special case in which the dielectric behaves as a free electron gas, excitation probabilities and dispersion relations are deduced for bulk and surface plasmons.
Spontaneous Recombination of Frenkel Pairs for Electron Irradiation
Authors: Dettmann K. , Leibfried G. , Schroeder K. 
Published: July 2007

AbstractThe damage rate for electron irradiation is calculated from the general equations for the spontaneous recombination of Frenkel pairs. The calculation uses the superposition approximation in which third order correlations are replaced by second order correlations. Comparison with the measurements of Dworschak et al. for 3 MeV electrons gives for copper an annealing volume, νa = 200 atomic volumes, and a fraction γ = 0.1 of interstitials, originally in unstable positions around their corresponding vacancies.
Paramagnetic Relaxation and Observation of a Phonon Bottleneck in Terbium Ethyl Sulfate
Authors: Kahle H.‐G. , Kalbfleisch H. , Stein K. 
Published: July 2007

AbstractA pulse modulated magnetic field is used to study the paramagnetic relaxation in terbium ethyl sulphate. This method can be used to obtain two different types of disturbance of the thermal equilibrium between the spin‐system and the phonons. It is seen that there are different relaxation functions and different dependences of the measured (effective) relaxation time Teff on the magnitude of the initial disturbance for both of these types of disturbance. The experimental results are in good agreement with the theory of paramagnetic relaxation which includes the phonon bottleneck.
Quenched‐in Levels in p‐Type Silicon
Authors: Elstner L. , Kamprath W. 
Published: July 2007

AbstractHall effect measurements are described on heat treated and quenched p‐type silicon crystals. Donor centres appear at (Ev + 0.37) eV after this treatment. Introduction and annealing studies indicate that these centres are vacancy clusters. Similar investigations are made on electron irradiated samples.
Theory of Weakly Bound Bloch Electrons in a Magnetic Field. II. Asymptotic Approximation
Authors: Fischbeck H. J. 
Published: July 2007

AbstractThe Schrödinger equation of an electron in a weak two‐dimensional periodic potential and a homogeneous magnetic field is solved by an asymptotic approximation which is essentially a generalization of the WKB method to systems of ordinary differential equations. This approximation proves to be the mathematical substantiation of the Pippard network model of magnetic breakthrough.
Eine Verallgemeinerung der Korringa‐Kohn‐Rostoker‐Methode zur Berechnung von Einelektronenzuständen in Kristallen
Authors: Bross H. , Anthony K. H. 
Published: July 2007

AbstractIm Rahmen der Einelektronennäherung wird ein Verfahren entwickelt, das mit Hilfe von Greenschen Funktionen die Elektronenzustände in idealen Kristallen zu berechnen gestattet. Gegenüber der von Korringa bzw. Kohn und Rostoker angegebenen Methode weist es folgende Vorteile auf: 1. Die Wellenfunktionen sind samt ihren ersten Ableitungen im ganzen Raum stetig. 2. Das Einelektronenpotential muß nur innerhalb einer um jedes Gitteratom gelegten Kugel sphärisch symmetrisch sein. Im Gebiet zwischen den Kugeln kann es beliebige Gestalt annehmen. 3, Es wird eine Greensche Funktion verwendet, die für alle Wellenvektoren definiert ist.
Die Interpretation des elektronenmikroskopischen Beugungskontrastes von Einschlüssen nahe einer kräftefreien Folienoberfläche
Authors: Chik K. P. , Wilkens M. , Rühle M. 
Published: July 2007

AbstractDer elektronenmikroskopische Beugungskontrast von sphärischen Einschlüssen nahe einer kräftefreien Folienoberfläche wird berechnet und mit Hilfe der Theorie der modifizierten Bloch‐Wellen kritisch diskutiert. Es wird gezeigt, daß der sogenannte Schwarz‐Weiß‐Kontrast (S‐W‐Kontrast) auf zwei Ursachen beruht: „Interbandstreuung”︁ zwischen den modifizierten Bloch‐Wellen und „Randbedingungen”︁, denen die Elektronenwellen an den Folienoberflächen genügen müssen. In Übereinstimmung mit McIntyre und Brown [12] finden wir, daß bei Einschlüssen mit hinreichend starker Verzerrung der umgebenden Matrix die „Tiefenoszillationen”︁ des S‐W‐Kontrastes unterdrückt werden. Es wird gezeigt, daß dieser Effekt unmittelbar auf Besonderheiten des Verschiebungsfeldes eines Einschlusses in der Nähe einer kräftefreien Oberfläche zurückzuführen ist.
On the Dielectric Function of a Semiconductor in an External Electric Field
Authors: Enderlein R. , Keiper R. 
Published: July 2007

AbstractThe field‐induced change in the intraband and interband parts of the complex dielectric function is calculated for the various types of critical points. The field‐induced change in the plasma frequency has a quadratic dependence on the field. Limits of validity for the effective mass approximation are given. The influence of collisions on the field‐induced change of the interband part of the dielectric function is dealt with.
Influence of Oxygen Segregations in Silicon Single Crystals on the Halfwidth of the Double‐Crystal Rocking Curve of Thermal Neutrons
Authors: Eichhorn F. , Sippel D. , Kleinstück K. 
Published: July 2007

AbstractOxygen segregations in silicon crystals produced by the Czochralski method are shown to be arranged on “Wendelflächen” by using the Schwuttke model. The crystal lattice therefore contains an anisotropic distortion field. A study is made of the effect of this distortion on the half‐width of double‐crystal rocking curves for thermal neutrons.
The Mechanism of Diffusion in B.C.C. Transition Metals
Authors: Peart R. F. , Askill J. 
Published: July 2007

AbstractA simple divacancy‐vacancy analysis has been applied to diffusion data in b.c.c. transition metals. Consideration of the divacancy contribution at high temperatures to diffusion coefficients determined with radioactive tracers is shown to be consistent with the nonlinear Arrhenius relationships for diffusion in V, Cr, β‐Ti and β‐Zr and with the corresponding linear relationships obtained for other b.c.c. metals.
Double Injection into CdS Single Crystals
Authors: Rohde H. J. 
Published: July 2007

AbstractSimple reaction kinetic models are developed, to describe the dark conductivity of CdS‐type photoconductors. In addition to recombination centres, shallow electron and hole traps are considered. Double injection characteristics, developed in making use of a neutrality approximation, contain a threshold voltage Vth for double injection which is identical to that of the Lampert model [1]. For the case of weak population of the trapping states, the threshold voltage is followed by a j ∼ V2 law. At higher population a power law j ∼ Vn (n > 2) is expected. When the voltage passes some maximum voltage Vmax > Vth the characteristic joins that of the Lampert model. Measurements at different temperatures and electrode separations show good agreement with the theoretical results. It is shown that filling of trapping states by single carrier injection at the trapfilled‐limit voltage VTFL and field ionization of filled centres can be excluded from the interpretation of the experimental results.
Berechnung des Peierls‐Potentials im Diamantgitter mit Hilfe der Pseudopotentialmethode
Authors: Teichler H. 
Published: July 2007

AbstractEs wird gezeigt, daß das Peierls‐Potential unter Berücksichtigung aller Paarwechselwirkungen zwischen den Atomen eines Kristalles durch die Fourier‐Transformierte des Wechselwirkungspotentials und der mit der Versetzung verbundenen Änderung des Strukturfaktors ausgedrückt werden kann. Zur Anwendung auf Schraubenversetzungen in Ge und Si wird das Verschiebungsfeld näherungsweise durch das Verschiebungsfeld einer Versetzung im anisotropen Kontinuum ersetzt. Das Wechselwirkungspotential zwischen den Atomen wird mit Hilfe der Pseudopotentialmethode bestimmt.
The Influence of s‐d Exchange on Relaxation of Magnons in Metals
Authors: Heinrich B. , Fraitová D. , Kamberský V. 
Published: July 2007

AbstractA study is made of the relaxation of resonance spin waves by the s‐d exchange interaction. In contrast to previous work, the s‐electron spin relaxation is considered explicitly. Calculated relaxation times compare well with the results of recent experiments on iron.
Pressure Dependence of Elastic Constants of Cesium Halides
Authors: Chang Z. P. , Barsch G. R. , Miller D. L. 
Published: July 2007

AbstractThe single crystal elastic constants of CsCl, CsBr, and CsI have been measured at 13 °C as a function of hydrostatic pressure. The maximum pressure ranged from 2.3 to 6 kbar but was extended up to 10 kbar for two runs. The pressure dependence of the elastic constants was found to be linear within experimental error. The experimental results are compared with theoretical data by Nran'yan and Ghate. Also, the stability of the cesium chloride structure under pressure is discussed.
Band‐Filling Model for Injection Luminescence at Higher Temperatures
Authors: Eliseev P. G. , Krasilnikov A. I. , Manko M. A. , Pinsker I. Z. 
Published: July 2007

AbstractAn analysis is made of a simplified model of impurity band filling in heavily doped semiconductors at relatively high temperatures. The thermal energykTis considered to be comparable with the characteristic energy parameter of the impurity band which describes the rate of decay of the density of state into the gap. Results of the analysis are applied to injection luminescence and are verified by a spectral study of the radiation from a number of diffusion and epitaxial GaAs diodes. Degenerate and non‐degenerate cases of the impurity band filling may be distinguished. The shifting peak in the former case and fixed thermal excited one in the latter case are expected. An unexpected result of the analysis is that the line‐width in the non‐degenerate case is temperature independent. This result is supported by the measurements. When the energy distribution of the density of states of the impurity band is Gaussian the line‐width is directly related to the dispersion of the distribution. Observed values of this dispersion reach 35 meV in heavily doped samples and exhibit a correlation with the donor concentration. Some other features of the model are also discussed.
Impurity‐Induced Far‐Infrared Absorption in the Phonon Gap Regions of KI and KBr
Authors: Grisar R. G. J. , Reiners K. P. , Renk K. F. , Genzel L. 
Published: July 2007

AbstractMeasurements are made on doped KI and KBr using a far‐infrared grating spectrometer, which is briefly described. The absorption of KI:OD− at 4.3 °K exhibits localized vibrational and translational gap modes. An attempt to assign these modes is made by proposing a term scheme. Measurements of doped KBr between 2.5 and 80 °K confirm the boundaries of the acoustic‐optical gap as 96 cm−1 and 100 cm−1, respectively.
The Effects of Defect Doping on Low Temperature Neutron‐Irradiation Damage and Recovery in Aluminium and Platinum
Authors: Swanson M. L. 
Published: July 2007

AbstractBy means of residual electrical resistivity measurements, low temperature neutron‐irradiation damage was investigated in Al and Pt which were doped with various defects. It was found that the damage rate of Al at 1.8 °K was almost unchanged by the addition of 0.5% Mg, and furthermore, that the presence of this impurity suppressed the damage rate enhancement normally caused by deformation of high purity Al. Similar results were obtained for IS Al, which contains 0.35% Fe + Si. These results indicate that the effect of channeling on the damage rate of Al is small. The damage rate of Pt was affected little by deformation, but was enhanced approximately 12% for samples containing ≈︁ 10−4 quenched‐in vacancies. The stage I recovery of Pt was increased 30 to 50% by deformation or by quenched‐in vacancies. The results were compared with those of other investigations. It was concluded that most of the differences between heavy and light particle irradiations were caused by the greater importance of long‐range focused collision sequences in the former.
Pressure Coefficient of the Band Gap in Mg2Si, Mg2Ge, and Mg2Sn
Authors: Stella A. , Brothers A. D. , Hopkins R. H. , Lynch D. W. 
Published: July 2007

AbstractThe pressure deri vative of the band gap, (∂E/∂P)T, has been determined to be + 3 × 10−6 e Vbar−1 for Mg2Sn by measurements of the pressure derivative of the electrical conductivity. Similar measurements on Mg2Si and Mg2Ge were inconclusive, but estimates of this parameter were made from the shift of the optical obsorption edge with pressure. (∂E/∂P)T = (0 ± 0.5) × 10−6 e Vbar−1 for both compounds. The similarity of the coefficients for Mg2Si and Mg2Ge suggests that the symmetries of the band edges of both compounds are similar, while either the conduction band edge, the valence band edge, or both edges in Mg2Sn may have a different symmetry.