bluuebunny/crossref_metadata_2025_split huggingface dataset:
Untersuchungen zum Mechanismus der Elektrolumineszenz von CdS‐Einkristallen
Authors: Hänsch H.‐j. 
Published: July 2007

AbstractAn investigation is made of the spectral distribution of intensity and the intensity‐current density dependence of electroluminescence (EL) of CdS single crystals at 77 °K. In the range of the short wave series of the edge emission good agreement is found between EL and photoluminescence (PL) spectra. Moreover, some short wavelength bands appear in EL, whose intensities increase essentially stronger than the edge emission with increasing current density. Analogously to the PL it is assumed that in the edge emission range the EL is due to a transition within a donor‐acceptor associate. The short wave EL bands are assigned to a radiative annihilation of a bound exciton assisted by longitudinal optical phonons and (presumably) acoustical ones. Although at large current densities the necessary laser condition is fulfilled, no laser action could be observed.
Optical Transitions in the Spectra of the Fundamental Absorption and Reflection of InSe Single Crystals
Authors: Andriyashik M. V. , Yu. Sakhnovskii M. , Timofeev V. B. , Yakimova A. S. 
Published: July 2007

AbstractThe spectrum of the fundamental absorption and reflection of n‐type InSe single crystals is studied in the energy region 1 to 5 eV and in the temperature range 293 to 90 °K. In the spectrum an absorption is observed which may be related to direct and indicrect interband transitions. The main parameters characterizing the indirect and direct optical transitions are determined. The fine structure in the absorption spectrum due to excitons is investigated. On the basis of the analysis of the optical absorption and reflection properties in the fundamental region and using selection rules, the character of optical transitions as well as the peculiarities in the energy band structure of InSe single crystals are established.
Effect of Reactor Irradiation on the Conductivity and the Photoconductivity of Hexagonal Selenium Single Crystals
Authors: Tuomi T. O. 
Published: July 2007

AbstractRadiation damage in selenium is investigated at various temperatures. Fast neutron irradiation is found to decrease the conductivity of a hexagonal selenium single crystal at 310 °K in an exponential manner. According to the barrier model the decrease of the conductivity is a result of the decrease in the hole concentration in the high conductivity regions. The photoconductivity measurements indicate that the fast neutron irradiation does not markedly change the properties of the barriers. At 80 °K the crystals are more sensitive to radiation than at 310 °K, whereas at 20 °K the effect of radiation on the conductivity is of the same order as at room temperature.
Stationary Anode‐Adjacent High‐Field Domains in Cadmium Sulfide
Authors: Böer K. W. , Voss P. 
Published: July 2007

AbstractIt is shown that in n‐type material with negative differential conductivity due to field quenching, stationary cathode‐ or anode‐adjacent high‐field domains occur dependent on electron density at the cathode and applied voltage. Cathode‐adjacent high‐field domains can be observed only with a blocking cathode. Anode‐adjacent high‐field domains occur with a slightly blocking cathode at applied voltages above the range at which cathode‐adjacent domains are observed or as the only domain type possible with an injecting cathode. With different cathode metals evaporated onto the same CdS:Ag, Al crystal the electron density in the conduction band n1(E) for space charge free conditions has been determined as a function of the actual field between 0 and 240 kV/cm.
Computational Evidence for the Transition Point of a Square Ising Lattice with First and Second Neighbour Interactions
Authors: Bitterlich W. , Jelitto R. J. 
Published: July 2007

AbstractFrom numerical calculations for a toroidally closed Ising lattice of finite diameter it is seen that it is possible to obtain the transition point of a square Ising lattice with nearest and next‐nearest neighbour interactions to a high degree of accuracy. In the case of a lattice with pure nearest neighbour interactions the curves of the internal energy for all diameters of the torus intersect in one point, which is the transition point of the infinite lattice. When next‐nearest neighbour coupling is present, this is no longer exactly valid, but the dependence of the situation of the different points of intersection on the diameter is so exceedingly weak that a rapid convergence to the Curie point may be assumed with increasing size of the lattice and the transition point can be deduced thereby. The assumptions involved in this method and its consequences are discussed and the result of the investigation is compared with a theory of Vaks et al., which deals with a similar type of interaction.
Innere optische Reflexionen an kubischem ZnS mit eindimensionaler Lagefehlordnung
Authors: Farwer A. , Matossi † F. 
Published: July 2007

AbstractDie inneren Reflexionen in eindimensional lagefehlgeordnetem kubischem Zinksulfid werden zwischen 350 und 1000 nm Wellenlänge untersucht. Da die Stapelfehler hexagonale Struktur besitzen, ist es möglich, die Verhältnisse der Hauptbrechungsindizes von Wurtzit und Sphalerit sehr genau zu bestimmen. Für 360 nm Wellenlänge ergibt sich nhex, o/nkub  0,980 und nhex, ao/nkub  0,990, wahrend für 850 nm die entsprechenden Werte 0,993 und 1,003 sind. Der mittlere Abstand zwischen den Stapelfehlern kann zu etwa 100 Å abgeschätzt werden.
On the Thermal Conductivity of ZnxHg1−xTe Solid Solutions
Authors: Kelemen F. , Néda A. , Cruceanu E. , Niculescu D. 
Published: July 2007

AbstractThermal conductivity measurements are carried out in single crystals of ZnxHg1−xTe solid solutions as a function of composition and temperature between 90 and 450 °K. The temperature dependence of the thermal conductivity in ZnTe may be explained by U‐processes. At the same time, the lattice thermal conductivity measured in these solid solutions is lower than that calculated on the basis of U‐processes and phonon scattering at point defects. Therefore it is assumed that the interaction between acoustical and optical phonons as well as the three‐phonon N‐processes also contribute to the thermal resistivity in these solid solutions. In the light of this assumption, a satisfactory agreement is found between the experimental and the calculated values of the lattice thermal conductivity.
Investigations of Some Properties of Vitreous and Crystalline CdGeP2
Authors: Goryunova N. A. , Ryvkin S. M. , Shpenikov G. P. , Tichina I. I. , Fedotov V. G. 
Published: July 2007

AbstractRecombination radiation is observed in vitreous and crystalline CdGeP2. Some electric properties of vitreous and crystalline specimens are also studied. n‐ and p‐type crystals with concentrations n = 6 × 1010 to 7 × 1015 cm−3 and p = 7 × 1014 to 4 × 1015 cm−3 at 300 °K and p‐type vitreous CdGeP2 are used. The effect of the recrystallisation of vitreous CdGeP2 as well as the effect of impurities on the recombination radiation of crystalline CdGeP2 is investigated.
Elastic Constants and Tensile Strength of NaCl‐Type Alkali Halides
Authors: Szomor P. O. 
Published: July 2007

AbstractThe second‐order elastic constants and tensile strength of NaCl‐type alkali halides are calculated on the basis of the Born‐Mayer model of the lattice energy of ionic solids. The repulsive parameters which include the contribution of the second nearest neighbours in the expression of the repulsive energy are obtained from the equation of state of static solids and its volume derivative. For determining the elastic constants and the tensile strength a procedure similar to Zwicky's procedure is chosen. The comparison of the calculated elastic constants and the available experimental results show that the basic radii obtained by the Huggins‐Meyer procedure are not accurate enough in the case of certain ions.
The Electronic Structure of CdO I. The Energy‐Band Structure (APW Method)
Authors: Maschke K. , Rössler U. 
Published: July 2007

AbstractThe energy‐band structure of CdO was calculated along the high symmetrical axes of the Brillouin zone by use of the APW method. This method seems to be more suitable for the rocksalt lattice than for the zincblende structure. The resulting energy bands are similar to the bands of silver halides.
EPR and Thermoluminescence Measurements on CaWO4 Crystals
Authors: Born G. K. , Grasser R. J. , Scharmann A. O. 
Published: July 2007

AbstractAfter irradiation with X‐rays in the energy range 50 to 150 keV at the temperature of liquid air paramagnetic centres are created in single crystals of CaWO4. The centre with a spectroscopic splitting factor slightly higher than g = 2 originates from a hole stably trapped between two tungstate tetrahedrons. The signal of the corresponding electron is broad and rather difficult to detect. The concentration of these centres depends linearly on the dose of irradiation. The decrease of the EPR signal of the hole and electron centres with temperature is correlated with the thermoluminescence intensity.
Hall Effect and Magnetoresistance in Copper Single Crystals at Low Temperatures
Authors: Saeger K. E. 
Published: July 2007

AbstractThe Hall coefficient and transverse magnetoresistance of copper single crystals of different purity are measured in dependence on the magnetic field strength, temperature, and crystal orientation. For high magnetic fields and low temperatures, Kohler's rule is valid for both effects in pure samples for all crystal orientations investigated. Departures from Kohler's rule occur for increasing temperatures and impurity contents. The investigation of the temperature dependence of the Hall coefficient shows that the maximum in the Hall coefficient versus temperature curves recently found by several authors is due to anisotropic electron‐phonon scattering. The results of the present investigation indicate that the temperature dependence of the low field Hall coefficient differs significantly from that previously assumed to be valid.
Electron Irradiation and Recovery of Tungsten
Authors: Neely H. H. , Keefer D. W. , Sosin A. 
Published: July 2007

AbstractDamage rates and recovery of 99.99% pure tungsten have been investigated after electron irradiation near 4 °K by means of electrical resistivity. The damage rate data tend to a value of T0 = 38 to 42 eV. The recovery of the residual electrical resistivity shows three major stages: Stage I from 4.2 to 100 °K, Stage II from 100 to 500 °K, Stage III from 500 to 1000 °K. Stage I is dominated by only one major peak at 70 °K. An analysis based on second‐order kinetics yielded a good fit to the data through 95% of the recovery. The energy derived was 0.17 eV. Only ≈︁ 26% recovery is seen in Stage I and we propose that the suppression is due to interstitial trapping by impurities. Stage III accounts for about 40% recovery of the induced resistivity and has a center temperature of 760 °K. The stage was analysed assuming second‐order kinetics; this analysis gave an energy of 1.1 eV.
On Transverse Electrical Conductivity of Metals
Authors: Kishore R. 
Published: July 2007

AbstractWith the help of the Kubo formula an expression for the transverse electrical conductivity of metals is obtained within the Hartree‐Fock approximation using the method of the double‐time temperature‐dependent Green's function. It is observed that the expression is the same as that obtained by Leribaux with the help of perturbation theory using the Feynman diagram technique if the change in the energy of the electrons due to electron‐phonon interaction is neglected.
Thermal Quasi‐Equilibrium of Vacancies, Divacancies, and Impurities in Platinum
Authors: Polák J. 
Published: July 2007

AbstractThe change in the electrical resistivity of platinum quenched in air and in water is measured. The transient phenomenon at the very beginning of the isothermal annealing at a temperature of about 250 °C is observed. The possible interactions of point defects in quenched platinum are analysed. Various interactions are quantitatively compared with the measured data and the probable interpretation of the results is discussed.
Calculation of the Point Lattice Potential of a Bounded Crystal
Authors: Vendik O. G. 
Published: July 2007

AbstractThe eigenfunctions of the electrostatic potential in a rectangular box were used for the calculation of the potential of a point lattice of an ionic crystal. The potential within the bounded crystal and in its surface region was found. The final result was obtained in the form of an expansion in spherical harmonics referred to coordinates whose origin could be at any lattice point of the crystal. The method was used to explain an experiment [8] dealing with electron diffraction from the surface layers of BaTiO3.
Injection of Current Carriers in Anisotropic Semiconductor Plates and the Magnetodiode Effect
Authors: Gribnikov Z. S. , Lomova G. I. , Romanov V. A. 
Published: July 2007

AbstractIt is shown that the current‐voltage characteristics in of plate‐ or filament‐shaped long diodes are essentially different for the isotropic and anisotropic cases. For the effective lifetime of excess carriers in anisotropic case is inversely proportional to the external electric field, the direct current through such a diode increases slower than I ∼︁ U2, that is “ohmically” I ∼︁U. As a result of such difference the characteristics of the isotropic plate‐shaped diodes strongly depend on pressure and magnetic field (the effect of a small magnetic field may be considered to be equivalent to the effect of pressure). This indicates that significant tensodiode and magnetodiode effects take place. A satisfactory agreement of the experimental data with the theory has been obtained.
A Dynamical Treatment of the Stress‐Induced Dissociation of Triangular Frank Dislocation Loops in F.C.C. Metals
Authors: Humble P. , Forwood C. T. 
Published: July 2007

AbstractThe problem of the dissociation of triangular Frank dislocation loops to form stacking fault tetrahedra during the plastic deformation of f.c.c. metals is reconsidered. It is pointed out that since this process involves the movement of dislocations, any consideration of the energy balance of the defect must take into account the kinetic energy of the moving dislocations. The problem is reformulated in terms of the total energy of the system where terms in the kinetic energy, the work done by the stress, and the energy dissipated are included, as well as the energy due to dislocation interactions and stacking faults. Using this formulation and the observations of Loretto et al. [3], it is deduced that the values for the stacking fault energy of silver, copper, and gold are (19 ± 3), (62 Melbourne 9), and (47 ± 7) erg cm−2, respectively.
Absolute Thermoelectric Power and Electrical Resistivity of Chromium‐Rich Chromium–Nickel Alloys
Authors: Schröder K. , Baum N. P. 
Published: July 2007

AbstractThe absolute thermoelectric power S and resistivity ϱ of chromium‐nickel alloys with up to 10 at% nickel were measured between 100 and 600 °K. Both ϱ and S were linear functions of the temperature above room temperature. Alloys with less than 4 at% nickel showed at lower temperatures a maximum in ϱ and S, which was attributed to antiferromagnetic ordering. The Néel temperature decreases about 100 °K/at% Ni.
Infrared Lattice Absorption of Silicon and Germanium
Authors: Kress W. , Borik H. , Wehner R. K. 
Published: July 2007

AbstractThe two‐phonon absorption bands of silicon and germanium are calculated taking into account the second‐order dipole moment up to second‐nearest neighbours. The agreement between the calculated and measured bands shows that the shell model used in our calculations gives quite good phonon dispersion curves. The detailed analysis of the remaining deviations between measured and calculated frequencies indicates that in some points of the Brillouin zone the shell model should be corrected.
Change in Electron Affinity of a Semiconductor due to Different Forms of Chemisorption
Authors: Ahmad L. 
Published: July 2007

AbstractA model has been proposed for the calculation of the variation in electron affinity, with the changes in the degree of surface coverage, for the case where different forms of a given gas species are chemisorbed on a semiconductor surface. This model embodies two parameters, which can be selected to fit the experimental results. It has been applied to the problem of oxygen chemisorption on the deformed (100) BaTiO3 surface. Neutral and ionic forms of chemisorption are postulated. The dipole moment associated with the neutral form, the higher attainable coverage, and the corresponding change in the electron affinity were found to be ≈ 3.1 D, ≈ 0.54, and ≈ 3.2 eV, respectively.
Interpretation of Self‐Diffusion and Vacancy Properties in Gold
Authors: Seeger A. , Mehrer H. 
Published: July 2007

AbstractMeasurements of the self‐diffusion coefficient and the high‐temperature equilibrium concentration of vacant lattice sites in gold are reanalysed in a critical manner. The analysis takes into account divacancy contributions and temperature dependences of the activation energies and entropies. A consistent set of self‐diffusion and vacancy parameters is derived. Previous interpretations, in particular those of Stoebe and Dawson [25] and Wang, Seidman, and Balluffi [20], are criticized.
Untersuchung der magnetischen Nachwirkung in Nickel nach Neutronenbestrahlung und plastischer Verformung
Authors: Walz F. 
Published: July 2007

AbstractDie Nachwirkung der Anfangssuszeptibilität in Ni‐Einkristallen nach Neutronenbestrahlung und plastischer Verformung wird zwischen −180 und s+150 °C eingehend untersucht. Bei − 128, − 100, − 80, − 38 und − 21 °C werden ausgeprägte Nachwirkungsmaxima beobachtet, die durch einfache Relaxationsprozesse beschrieben werden können. Zwischen 0 and +150 °C tritt – auch nach plastischer Verformung – ein wenig strukturiertes Relaxationsgebiet auf, das bei +50 °C ein breites Maximum besitzt. In Übereinstimmung mit zusätzlich durchgeführten Koerzitivkraftmessungen und Erholungsexperimenten werden die beobachteten Relaxationsprozesse der Umorientierung kleiner anisotroper Komplexe aus Eigenfehlstellen bzw. Eigenfehlstellen und Fremdatomen, zugeschrieben.
On the L‐Bands and the First Exciton Bands in the Photoemission Spectra of Alkali Iodides
Authors: Petrescu P. 
Published: July 2007

AbstractThe photoemission spectra of NaI, KI, RbI and CsI are investigated experimentally. Besides the bands already revealed by optical absorption measurements and confirmed by photoemission studies, the L1–L4‐bands in Nal, the L4‐band in RbI, and the fine structure of the E1‐bands in KI and RbI are observed. In CsI electron emission is detected corresponding to the first exciton band in the absence of F‐centres. The very intense “extra”‐bands occurring in the absorption spectra are not found.
A Phase Transition and the Photoemissive Quantum Yield at Low Temperatures in Cs3Sb Films
Authors: De'Munari G. M. , Giusiano F. , Mambriani G. 
Published: July 2007

AbstractBy means of a recently developed method the photoemissive quantum yield (Y) of Cs3Sb films is measured as a function of temperature at very low light intensities. A strong evidence for the existence of Cs3Sb in two phases one of which (phase II) is the known “state” with high Y is found. The other phase (I) has a much lower Y which depends strongly on the light intensity. Phase I exists only below (260 ± 2) °K: above this temperature it transforms to phase II. The existence of phase I up to now was not noticed because it is very sensitive to the absorbed light energy which easily can convert it to phase II. We suggest for phase I the regular body‐centred cubic structure and for phase II the pseudo‐body‐centred cubic structure found at room temperature by Jack and Wachtel. Moreover, we propose for Cs3Sb an energy band structure with a split valence band. The observed dependences of Y on temperature and light intensity are discussed in this framework. Even other Cs3Sb properties seem to fit rather well the proposed energy band and crystal structure.
Deformation Modes of the Intermediate Phase NiAl
Authors: Pascoe R. T. , Newey C. W. A. 
Published: July 2007

AbstractThe deformation modes of single crystal NiAl deformed in compression in the range 77 to 1000 °K were found to be dependent on orientation and temperature. The preferred slip direction was confirmed as 〈001〉, but this may be constrained geometrically to allow kinking, or slip in 〈111〉 or 〈011〉 directions, depending on temperature. When 〈001〉 slip occurred, the slip plane was invariably {110} at 77 °K but was dependent on orientation at higher temperatures. The slip planes were also sensitive to temperature when slip occurred in other directions. The von Mises criterion for polycrystalline ductility can be satisfied by combinations of the observed slip systems.
A Deformable Shell Model for the Alkali Halides
Authors: Basu A. N. , Sengupta S. 
Published: July 2007

AbstractThe simple shell model which takes account of the polarizability of the ions is improved by including the effect of deformations of the electron shell during the vibrations of the ions. The deformability is introduced in a phenomenological way and it is shown that this ultimately leads to three body interactions between like particles. Because of the inclusion of many body effects the elastic constants do not satisfy in general the Cauchy relation C12 = C44. The theory is applied to the calculation of the dispersion curves for NaI and the result is compared with the simple shell model curves and with the curves obtained by neutron diffraction experiments. Definite improvement of the agreement for the deformable shell model is noticed.
Energy Loss of 〈110〉 Channelled α‐Recoil Atoms in Gold
Authors: Ibel K. , Sizmann R. 
Published: July 2007

AbstractUsing time‐of‐flight technique, the differential energy loss of channelled Pb‐208 (169 keV), Pb‐210 (146 keV), and Tl‐208 (116 keV) recoil atoms along the 110 direction in gold is investigated. The results are − dE/dz = (34.7 ± 3.5), (35.1 ± 3.1), and (36.8 ± 8.3) eV/Å at transverse energies of the aligned motion to the string direction of 140, 120, and 105 eV, respectively. Theoretical considerations based on Lindhard's string treatment and Firsov's impact parameter dependent electronic energy transfer relation strongly suggest that the measured stopping powers of the aligned motion are predominantly electronic; in random motion nuclear energy loss is preponderating.
The Structure and Properties of the Semiconducting Compound ZnSnP2
Authors: Vaipolin A. A. , Goryunova N. A. , Kleshchinskii L. I. , Loshakova G. V. , Osmanov E. O. 
Published: July 2007

AbstractThe position of the P‐atom in the ordered structure of chalcopyrite type ZnSnP2 is determined: X = 0.239. Crystals with various degrees of ordering are obtained by varying the cooling rate of the melt during growth. The partly ordered crystals show a mosaic structure and consist of blocks having chalcopyrite or sphalerite structure. The dependence of the degree of ordering on the cooling rate is established. From measurements at room and liquid nitrogen temperature the Debye temperature is found to be the same for crystals with different degree of ordering. The mean‐square displacements of atoms as well as the microhardness increase with disordering, and may be related to defect formation. A decrease in the Hall mobility of holes is directly connected with the degree of disordering.