bluuebunny/crossref_metadata_2025 huggingface dataset:
On a simple derivation of the amplitudes of the electron beams transmitted and scattered by a crystal containing planar interfaces — images of subgrain boundaries
Authors: Gevers R. , van Landuyt J. , Amelinckx S.
Published: July 2007

A calculation is made of the amplitudes of the waves transmitted and scattered by a plate‐shaped foil formed by the superposition of two parallel plate‐shaped crystals. The diffraction vectors, the excitation errors, the extinction distances, the absorption lengths, and the phase‐angles of the Fourier coefficients of the internal potential are assumed to be different in the two crystals. The amplitudes can be readily derived from the corresponding expressions for a perfect plate‐shaped foil. These expressions are found by considering the transmitted and scattered beams to arise from the interference of two plane waves with slightly different wave vectors. The method can be generalized to a plate‐shaped foil formed by the superposition of more than two parallel crystals. Assuming the column approximation to be valid a brief discussion is given of the different types of images resulting from planar interfaces. The images due to low angle subgrain‐boundaries are discussed in some detail and observations are presented. These images are often complicated by the superpositions of “wedge crystal” pseudo‐periodic fringe patterns and the “moiré” type of fringe patterns which are strictly periodic.
Infrared absorption by excitons due to photoionization and intraband lattice scattering
Authors: Moskalenko S. A. , Khadshi P. I.
Published: July 2007

A quantum mechanical theory is developed for infrared absorption by excitons due to photoionization and intraband lattice scattering. The theory involves the interaction of the excitons with the acoustic and optical phonons. The Maxwellian and Bose‐Einstein distribution functions and the possible locations of the simple exciton band extremum are taken into account. The effect of the exciton photoionization is observable at the threshold frequency at comparatively low exciton concentrations.
Nuclear magnetic resonance of 63Cu and 65Cu in copper
Authors: Tompa K.
Published: July 2007

The anisotropy of the NMR spectrum of 65Cu is measured using copper foils with {100} 〈001〉 cubic texture. X‐ray diffraction measurements and NMR second moment calculations on the texture show that the “quasi‐single crystal” assumption can be used to interpret the second moment measurements. Investigations are made on the NMR of both copper isotopes in powder samples of various origins to elucidate the origin of the excess moment. The Ruderman‐Kittel interaction constant, Aij′/h computed for the first neighbours from the difference ΔM − ΔM between the excess moments is found to be (200 ± 50) Hz. The first order quadrupole effect due to impurities also contributes to the excess moment.
Untersuchung der Schwingungseigenschaften des Oszillistors
Authors: Elietner H. , Kempe N.
Published: July 2007

Die Schwingungseigenschaften des Oszillistors werden in Abhängigkeit von der Größe des elektrischen und magnetischen Feldes und vom Winkel zwischen elektrischem und magnetischem Feld untersucht. Neben einer Grundmode, die in der Nähe der Schwellen‐werte des Schwingungseinsatzes rein auftritt, tritt unter bestimmten Bedingungen auch eine höhere Frequenz rein auf. Schwingungsbereich, Amplitude und Frequenz zeigen bezogen auf die Magnetfeldrichtung charakteristische Unsymmetrien, die sich besonders deutlich durch Änderung der Schwingungseigenschaften bei Umpolung des Magnetfeldes bemerkbar machen.
Reaction kinetics of stage III recovery in aluminium after neutron irradiation
Authors: Isebeck K. , Müller R. , Schilling W. , Wenzl H.
Published: July 2007

Low temperature neutron irradiation of high purity aluminium (up to a dose of 7.2 × 1017 nvt) produces a resistivity change of Δϱ = 5 × 10−8 Ωcm measured at 90.2 °K. The recovery is studied for isochronal and isothermal annealing in the stage III temperature range from 180 to 263 °K. This entire recovery region is uniquely activated with an activation energy of (0.58 ± 0.02) eV. The recovery mechanism is found to be bimolecular, the initial recovery being due to the correlated recovery of defects situated at small relative distances in defect clusters. The last 50% of stage III follow second order kinetics. The capture volume for interstitial‐vacancy recombination can be determined from the measurements. The results support the theory that in stage III interstitial atoms migrate freely and recombine with vacancies.
On the formation of single crystal films of F.C.C. metals on alkali halide cleavage planes in ultrahigh vacuum
Authors: Kunz K. M. , Green A. K. , Bauer E.
Published: July 2007

Thin films of Au, Al, and Ag are evaporated in an ultrahigh‐vacuum reflection electron diffraction unit onto NaCl, KCl, and KI {100} surfaces cleaved in air and in situ. Their structure is studied by reflection diffraction during and after deposition, and by transmission electron diffraction microscopy. The results of simultaneous evaporation onto crystals with different surface condition (air versus vacuum cleaved) or composition show that the different stages of film growth (mainly nucleation and coalescence) depend in a complicated manner upon surface condition and composition. Electron irradiation prior and during deposition, preannealing of the air cleaved surface, and annealing of the film after deposition strongly influence the film structure.
Die kritische Schubspannung kubischer Kristalle mit Fehlstellen tetragonaler Symmetrie. III. Elektronen‐ und neutronenbestrahltes Aluminium sowie elektronenbestrahltes Kupfer
Authors: Frank W.
Published: July 2007

Aluminium enthält nach Elektronen‐ und Neutronenbestrahlung dispers verteilte Zwischengitteratome in der Hantelkonfiguration. Entsprechendes gilt für Kupfer nach Elektronenbestrahlung. Es wird gezeigt, daß der in diesen Fällen beobachtete Zuwachs der kritischen Schubspannung infolge von Bestrahlung quantitativ durch die kurzreichenden elastischen Wechselwirkungen erklärt werden kann, welche die Versetzungen mit Zwischengitteratomen in unmittelbarer Nähe ihrer Gleitebenen besitzen.
The geometry of charged dislocations in the NaCl structure
Authors: Brantley W. A. , Bauer Ch. L.
Published: July 2007

Various dislocation configurations are examined in the NaCl structure for the presence of localized electrostatic charge assuming slip systems of the {110} 〈110〉 type. Pure edge and screw dislocations do not display an effective electrostatic charge. However, edge dislocations that possess a jog length of a √2/4 or an abrupt kink length of a √2/8 display a virtual charge of ± q/2 whereas edge dislocations that possess a jog length of a √2/2 or an abrupt kink length of a √2/4 are electrically neutral (a is the lattice parameter and q is the ionic charge). Similarly, screw dislocations that possess a jog length of a √2/4 or an abrupt kink length of a/4 display a virtual charge of ±q/2 whereas screw dislocations that possess a jog length of a√2/2 or an abrupt kink length of a/2 are electrically neutral. Either type of jog can be formed on a dislocation, but charged kinks must occur in electrically neutral pairs. Intersection between dislocations on orthogonal slip planes yields only neutral jogs whereas intersection between dislocations on oblique slip planes yields only charged jogs and neutral kinks. Nodes formed by the intersection of n edge dislocations display a virtual charge of ±q/2 whenever n is odd (n ≠ 1) and are electrically neutral otherwise. The emergence point of a dislocation on an atomically flat surface always is neutral although the point may acquire a charge of ±q by ion transport. In general, the presence of a charge of ±q/2 denotes an infinite source (or sink) for anion and cation vacancies whereas a charge of ±q denotes an expendable source.
Der Einfluß von überschüssigem antistrukturellem Bi auf die Wärmeleitfähigkeit des Kristallgitters von Bi2Te3, Bi2Te3‐Sb2Te3 und Bi2Te3‐Bi2S3 mit Jodbeimischung
Authors: Kutasov V. A. , Smirnov I. A.
Published: July 2007

Der Wärmewiderstand von Jod‐dotiertem Bi2Te3, Bi2Te3‐Sb2Te3 und Bi2Te3‐Bi2S3 wird gemessen. Es wird festgestellt, daß das Additivitätsgesetz für den Wärmewiderstand der durch die Jodbeimischung hervorgerufen wird, nicht erfüllt ist. Die Abweichung von diesem Gesetz ist durch das Vorhandensein von überschüssigem Bi in dem untersuchten Material zu erklären, das antistrukturell die Te‐Plätze einnimmt.
Electrical resistivity and longitudinal electrical magnetoresistivity of palladium‐rich palladium‐erbium alloys at low temperatures
Authors: Arajs S. , Dunmyre G. R. , Dechter S. J.
Published: July 2007

Electrical resistivity of palladium‐erbium alloys, containing 0.50, 1.00, 1.93, 3.97, 5.22, and 6.63 at% erbium, have been studied between 4 and 40 °K. In spite of localized magnetic moments on erbium atoms, no anomalies of any type are observable in the electrical resistivity curves. These palladium‐erbium alloys approximately obey the Matthiessen rule. Longitudinal magnetoresistivity measurements at 4.2 °K in fields up to 60 kOe have been made on the same alloys. The total longitudinal magnetoresistivity rapidly decreases from positive values to zero values with increasing erbium concentrations. The magnetoresistivity for 5.32 and 6.63 at% erbium alloys is essentially zero at any magnetic field value. The change in the magnetic component of the total resistivity has been found to be extremely small. The electrical resistivity increase due to 1 at% erbium in palladium is about 2.9 μΩcm.
Anisotropy of the photoemission from some coloured alkali halides
Authors: Petrescu P. , Gheordânescu V.
Published: July 2007

Crystals of coloured alkali halides showing dichroism display a marked anisotropy in the photoemission stimulated by polarized light. The results obtained by a new experimental technique are discussed and compared with those obtained for anisotropic colour centres by conventional optical methods.
Über ein Modell zur Berechnung der Entmagnetisierungskurven von Hartferriten
Authors: Heinecke U.
Published: July 2007

Es wurde die Ausdehnung von Strontiumferritkristallen in Richtung der hexagonalen Achse und senkrecht dazu durch Ausmessen einer großen Anzahl von Körnern auf Schliffbildern anisotroper Strontiumferritmagnete bestimmt. Als Modell für den Magneten wird ein aus verkürzten Rotationsellipsoiden dieser Abmessungen zusammengesetztes Aggregat angesehen. Für die innere Feldstärke erhält man dann einen positiven Wert. Die Berechnung des Anfangsteils der Entmagnetisierungskurve kann auf den Fall einer kettenförmigen Anordnung der Teilchen reduziert werden.
Identification and morphology of oxide particles in internally oxidized Cu–Mn alloys
Authors: Howling D. H.
Published: July 2007

Electron microscopy of internally oxidized Cu—Mn alloys has established that the dominant oxide formed is MnO (manganosite). This was confirmed by X‐ray measurements. The presence of γ‐Mn2O3 (γ manganese sesquioxide) and Mn3O4 (manganese spinel) have also been identified. The morphology and orientation of the oxide particles shows that the preferred growth form is of cubic shape, the oxide particles maintaining crystallographic continuity with the Cu matrix.
Bestimmung der Stapelfehlerenergie kubisch‐flächenzentrierter Metalle aus der Analyse des elektronenmikroskopischen Beugungskontrastes von Stapelfehlerdipolen
Authors: Häussermann F. , Wilkens M.
Published: July 2007

In der vorliegenden Arbeit wird aus dem elektronenmikroskopischen Beugungskontrast von Stapelfehlerdipolen in verformten kubisch‐flächenzentrierten Metallen die spezifische Stapelfehlerenergie bestimmt. Der elektronenmikroskopische Beugungskontrast von Stapelfehlerdipolen wurde in Abhängigkeit von der Geometrie des Stapelfehlerdipols und von verschiedenen Parametern (Tiefe, Anregungsfehler, Foliendicke) berechnet. Auf Durchstrahlungsaufnahmen von Kupfer, Gold, Silber, Nickel und Nickel‐Kobalt‐Legierungen wurden Stapelfehlerdipole gefunden und deren Kontrastbreiten gemessen. Aus der maximalen Kontrastbreite kann man mit Hilfe der Ergebnisse unserer Kontrastrechnungen und der Stabilitätsberechnungen von Seeger und Wobser [17] obere Grenzen der Stapelfehlerenergien angeben. Es ergaben sich die Werte: γCu = 59 erg/cm2, γAu = 42 erg/cm2, γAg = 22 erg/cm2, γNi = 180 erg/cm2, γNi‐40% Co = 78 erg/cm2, γNi‐60% Co = 49 erg/cm2, γNi‐67% Co = 47 erg/cm2.
Der g‐Faktor von F‐Zentren in Alkalihalogenid‐Kristallen
Authors: Schmid D.
Published: July 2007

Der g‐Faktor von F‐Zentren in 15 verschiedenen Alkalihalogenid‐Kristallen wurde mit Elektronenspinresonanz bei 24000 MHz gemessen. Die Abweichungen Δg vom g‐Faktor des freien Elektrons liegen zwischen 5 × 10−4 (LiF) und 5,3 × 10−2 (RbJ). Diese Abweichungen können an Hand eines von Adrian vorgeschlagenen Modells gedeutet werden: Das ungepaarte Elektron ist im elektrischen Feld der Nachbarkerne einer Spin‐Bahn‐Wechselwirkung ausgesetzt. Die numerische Berechnung der g‐Faktor‐Verschiebung wird durch die Verwendung der gemessenen anisotropen Hyperfeinstruktur‐Konstanten b sehr erleichtert. Man erhält befriedigende Übereinstimmung zwischen den berechneten Werten und den Meßwerten, wenn die nächstbenachbarten Kationen den Hauptbeitrag zur g‐Faktor‐Verschiebung liefern. Die Übereinstimmung wird schlechter, wenn der Beitrag der Anionen stärker ins Gewicht fällt. Bei ausgerichteten Lithium‐FA‐Zentren in KCl wurde eine Anisotropie des g‐Faktors beobachtet, deren Wert g⟂ − g∥ = (11 ± 4) × 10−4 innerhalb der Fehlergrenzen mit dem theoretisch erwarteten Wert von 9 × 10−4 übereinstimmt.
The effective mass of electrons in (InSb)x·(InTe)1−x crystals
Authors: Molodyan I. P. , Nasledov D. N. , Radautsan S. I. , Sidorov V. G.
Published: July 2007

Measurements of the thermoelectric power, transverse Nernst‐Ettinghausen effect, conductivity, and Hall effect allow the concentration and temperature dependence of the electronic effective mass m* to be calculated for crystals of the solid solution (InSb)x(InTe)1—x (for × = 1 to 0.85) in the temperature range 100 to 370 °K. Solid solutions having × > 0.99 (I) behave like InSb doped with tellurium, and crystals of this type having electron concentrations (n) greater than 2 × 1018 cm−3 show an m* (n) dependence which differs from that predicted by Kane. Solid solutions with x ≦ 0.99 (II) show a different temperature dependence of m* from those with x > 0.99.
Thermally activated motion of screw dislocations in B.C.C. metals
Authors: Vítek V.
Published: July 2007

The splitting of a 1/2 〈111〉 screw dislocation on one and three {110} planes, and on one and two {112} planes is assumed. It is proposed that repeated mutual transformations of these splittings during the motion of a screw dislocation control its thermally activated motion. Activation energies of these transformations are calculated as functions of the stacking fault energy, the external shear stress, and the orientation of the maximum resolved shear stress plane. The velocity of a screw dislocation is then calculated by the usual rate theory.
Dislocation theory of slip geometry and temperature dependence of flow stress in B.C.C. metals
Authors: Vítek V. , Kroupa F.
Published: July 2007

It is assumed that transformations of the splitting of a screw dislocation are continually repeated during its motion, and thus the screw dislocation crosses into different {110} and {112} planes [1]. On the basis of this mechanism a theory of the composite slip on {110} and {112} planes is established, and the dependence of the orientation of the slip plane on the orientation of the maximum resolved shear stress plane is calculated. The results are compared with the measurements of Taoka et al. [8] and Šesták and Zárubová [9]. Further it is shown that the same mechanism can account for the strong temperature dependence of the flow and yield stress.
Point defect electron scattering in Beryllium
Authors: van Torne L. I.
Published: July 2007

The dc resistivity due to electron scattering from a vacancy, an octahedral interstitial, and a tetrahedral interstitial in beryllium was computed by application of the diffraction model concept of pseudopotentials in the theory of metals. The resistivity values corresponding to one atomic percent concentration of each defect type are: octahedral interstitials, 0.283 μΩ cm; vacancies, 0.296 μΩ cm; and tetrahedral interstitials, 0.249 μΩ cm.
Piezowiderstand von p‐Germanium
Authors: Asche M. , Sarbej O. G. , Vasetskii V. M.
Published: July 2007

Es wurde der Piezowiderstand von p‐Germanium als Funktion des Druckes und der Verunreinigungskonzentration bei 77 und 300 °K gemessen. Die experimentellen Resultate zeigen, daß der Piezowiderstand von beiden Größen stark abhängt. Die Daten für kleine Drücke stimmen gut mit der Theorie der linearen Effekte überein, für höhere Drücke überwiegen die quadratischen Glieder.
Twinning in InS
Authors: Hogg J. H. C. , Duffin W. J.
Published: July 2007

Unusual features in X‐ray diffraction patterns from crystals of InS are shown to be due to a form of twinning. A model based on the crystal structure is proposed in order to explain the twinning mode and is confirmed by X‐ray and optical measurements.
Note on relaxation effects in Mössbauer spectra
Authors: van Zorge B. C. , Caspers W. J. , Dekker A. J.
Published: July 2007

A comparison is made between the van der Woude‐Dekker and Wegener models describing the effect of relaxation on the Mössbauer line shape. It is shown that both models lead to indentical basic formulae for the Mössbauer spectrum in terms of autocorrelation functions of the atomic spin. The approximation for short ion spin correlation times is discussed using a more general method than that used by Wegener.
The crystalline structure of ZnTe thin films
Authors: Spînulescu‐Carnaru I.
Published: July 2007

The crystalline structure of ZnTe thin films is studied as a function of stoichiometric and growth conditions. A determination is made of the optimum conditions for producing ZnTe thin films with pure hexagonal structure. The lattice constants of cubic and hexagonal ZnTe cells are computed.
Abhängigkeit des Supraleitverhaltens tordierter Niobeinkristalle vom Probendurchmesser
Authors: Nembach E. , Freyhardt H. , Haasen P.
Published: July 2007

An 〈110〉 orientierten Niobeinkristallen wurden Versetzungsdichte und magnetische Hysterese im supraleitenden Zustand als Funktion des Torsionswinkels für ca. 3 und 4 mm starke Proben gemessen.
Ein hochauflösendes Verfahren zur Untersuchung magnetischer Strukturen von Supraleitern
Authors: Träuble H. , Essmann U.
Published: July 2007

Magnetische Strukturen von supraleitenden oder ferromagnetischen Materialien können durch Verdampfen ferromagnetischer Substanzen in Heliumatmosphäre sichtbar gemacht werden. Das Verfahren zeichnet sich durch hohe Auflösung aus. Die Strukturen können lichtmikroskopisch und elektronenmikroskopisch (Replikaverfahren) beobachtet werden. Als Beispiel wurde der Zwischenzustand von supraleitendem Blei untersucht.
The rate of twin layer growth in bismuth single crystals
Authors: Startsev V. I. , Soldatov V. P. , Brodsky M. M.
Published: July 2007

The stress dependence of the normal and tangential rate of twinning is determined in bismuth single crystals of different purities. On the basis of experimental data it is concluded that the broadening of twin layers occurs by a heterogeneous mechanism. The activation volumes defining the processes of twin layer broadening and twin growth in the shear direction are determined. It is established that the process of twin layer broadening in bismuth involves the simultaneous reorientation of about 104 atomic planes and in each plane 10 to 102 twinning dislocations participate per centimetre length of twin plane in the shear direction.
Magnetic properties of Ce, Pr, and Nd monochalcogenides at 4.2 to 1300 °K
Authors: Smolenskii G. A. , Zhuze V. P. , Adamyan V. E. , Loginov G. M.
Published: July 2007

The magnetic properties of Ce, Pr, and Nd monochalcogenides are studied over a wide temperature range. The magnetic measurements at elevated temperatures show that the 4f electrons of metal ions are localized and their number is equal to that of the free tripositive metal ions. At low temperatures all the compounds investigated exhibit magnetic ordering except PrSe and PrTe. The possible types of magnetic ordering, and a mechanism for the exchange interaction, are discussed.
Change of the deformation mechanism (slip ⇄ twinning) in polycrystalline α‐iron
Authors: Moiseev V. F. , Trefilov V. I.
Published: July 2007

The conditions for the change of the deformation mechanism (slip ⇌ twinning) are investigated in the temperature range from −185 to 20 °C at the deformation rate . It is found that the strength parameters may be expressed by the Petch equation σ = σ0 + Kd−1/2 for twinning and slip deformation. The temperature dependence of the “frictional” stress and the term K for twinning are studied experimentally. The observed temperature dependence of the slope K is discussed in terms of stress relaxation near stress concentrations. The temperature dependence of the resolved twinning stress is determined by considering the stress concentration necessary for the start of a twinning source. An approximate expression is obtained for estimating the stacking fault energy from the temperature dependence of the yield stress of b.c.c. metals.
Small Angle Electron Scattering from Vacuum Condensed Metallic Films I. Theory
Authors: Wade R. H. , Silcox J.
Published: July 2007

We present the basis of a kinematic theory to account for electron diffraction effects from discontinuous vacuum condensed metallic films in which the separate particles act as scattering centres. The diffraction image depends on the variation in the interparticle spacings and is repeated in several layers of reciprocal space. The treatment is valid for any paracrystalline object.
Small Angle Electron Scattering from Vacuum Condensed Metallic Films II. Experimental Results
Authors: Wade R. H. , Silcox J.
Published: July 2007

The electron microscope is used as a small angle diffraction camera, with an angular resolution of about 5 × 10−6 rad, to investigate the structure of some vacuum deposited metallic films. Film structure is sensitive to condensation rate and radiant heat received from the vapour source. The growth of crystallites as separate columns is favoured by slow condensation rates in the case of nickel, permalloy, and palladium whilst at faster rates the films become continuous at an earlier stage in their growth. The sensitivity of the diffraction effects on the film structure is demonstrated and the general relations proposed in Part I are verified.
On the Theory of Interfacial Energy and Elastic Strain of Epitaxial Overgrowths in Parallel Alignment on Single Crystal Substrates
Authors: Jesser W. A. , Kuhlmann‐Wilsdorf D.
Published: July 2007

Refined expressions, amendable to experimental testing, for the equilibrium elastic strains in epitaxial overgrowths are derived, based on earlier theories by van der Merwe and Cabrera. Continuous films as well as isolated nuclei on substrates are considered.
Piezo‐Hall Effect in n‐Type Germanium
Authors: Walton A. K. , Eyoku G. J. O.
Published: July 2007

The piezo‐Hall effect has been measured at room temperature in germanium specimens doped with ≈︁1015 and ≈︁1018 Sb atoms per cm3. An experimental arrangement was used in which the stress and magnetic field were along a 〈111〉 valley symmetry direction and the current and Hall probes in the normal plane. The experimental results for ≈︁1018 cm−3 material are in accord with the simple electron transfer model with a mobility anisotropy of 7. The ≈︁1015 cm−3 material shows an anomalously small variation of Hall coefficient with stress. Possible explanations in terms of constancy of the net carrier concentration and intervalley scattering are discussed and rejected.
Verformungs‐ und Temperaturabhängigkeit der Magnetisierungsprozesse in Nickeleinkristallen I. Blochwandverschiebungen in 〈110〉‐ und 〈111〉‐Nickeleinkristallen
Authors: Köster E.
Published: July 2007

Die Magnetisierung und magnetostriktive Längenänderung stabförmiger Nickeleinkristalle wurde in Abhängigkeit von der plastischen Verformung und der Temperatur gemessen. Die Bereichsstruktur parallel zur 〈110〉‐ bzw. 〈111〉‐Stabachse entmagnetisierter Nickeleinkristalle besteht aus acht Phasen. Die vier zur Stabachse des 〈110〉‐Kristalls senkrecht magnetisierten Phasen nehmen 60%, die beiden parallel und antiparallel zur Stabachse des 〈111〉‐Kristalls magnetisierten Phasen nehmen 30% des Kristallvolumens ein. Die Phasenvolumina sind unabhängig vom Verformungsgrad und von der Temperatur. Bei 77°K sind die Koerzitivfeldstärke und die Anfangssuszeptibilität durch 180°‐Wandverschiebungen bestimmt, mit zunehmender Temperatur spielen Drehungen eine wachsende Rolle.
On the Kinetics of Short‐Range Ordering in AuAg (50,50) and CuAl (85,15)
Authors: van Den Beukel A. , Coremans P. C. J. , Vrijhoef M. M. A.
Published: July 2007

The establishment of short‐range order in the alloys AuAg (50,50) and CuAl (85,15) is investigated by electrical resistivity measurements on quenched wires. The kinetics of the process can be described by two equations based on the following assumptions: 1. The rate of ordering is proportional to the deviation from equilibrium order and to the number of vacancies. 2. The quenched‐in vancancies disappear by first order kinetics. 3. The activation energy Q of vacancy migration depends on the degree of order. During ordering Q appears to increase by a few hundredths of an eV in both alloys.
Interpretation of Deviating Points in the Relation between the Rate of Crystal Growth and the Relative Supersaturation
Authors: Bennema P. , Kern R. , Simon B.
Published: July 2007

A special weighing technique may be used to determine the rate of crystal growth R as a function of the relative supersaturation σ for growth from an aqueous solution [1, 2]. It is found that R is proportional to σ for potassium aluminium alum with 10−4 ⪅ σ ⪅ 10−2[1,3] but that for σ ⪆ 10−2 deviations occur from the linear form. In the present work these deviations are explained by assuming that a two‐dimensional nucleation mechanism and a spiral grooth mechanism occur simultaneously.
The Study of Defects in Quenched Nickel
Authors: Mughrabi H. , Seeger A.
Published: July 2007

Quenched nickel foils are investigated by electrical resistivity measurements, X‐ray small‐angle scattering and transmission electron microscopy. A marked dependence of the annealing behaviour on the purity of the specimens and the quenching atmosphere is observed. The quenched‐in vacancy concentrations are rather low, particularly in pure specimens where the total quenched‐in vacancy concentration is less than 5 × 10−6. In pure specimens one recovery stage only, centred at about 110°C, is observed between room temperature and 750°C. In less pure specimens a similar recovery stage is followed by a pronounced stage IV recovery (270°C) and a complex annealing behaviour above 400°C. The migration energies of mono‐ and divacancies are determined as E1VM = (1.4±0.05) eV and E2VM ⪆ (0.72±0.07) eV respectively. The divacancy binding energy is estimated as E2VM > 0.23 eV. This rather large value is thought to be responsible for substantial vacanxcy losses during quenching.
Elektronenmikroskopie kleiner Fehlstellenagglomerate in bestrahlten Metallen I. Theorie des Kontrastes und experimentelle Methoden zur Ermittlung des Defekttyps
Authors: Rühle M.
Published: July 2007

Durch Teilchenbestrahlung entstehen in Metallen elektronenmikroskopisch beobachtbare Fehlstellenagglomerate. Die Struktur der Fehlstellenagglomerate ist dann jedoch nicht mehr unmittelbar aus dem Kontrastbild zu entnehmen, wenn die Defekte kleiner als ca. 150 Å sind. Jedoch läßt sich durch Vergleich von gezielten Experimenten (dynamische Zweistrahl‐Abbildung) mit den Ergebnissen der Theorie des Kontrastes der Typ dieser kleinen Defekte (d. h. mögliche einfachste Form der Defekte und Unterscheidung zwischen Leerstellen‐ und Zwischengitteratomagglomeraten) ermitteln. Diese Analyse wurde an den in neutronenbestrahltem Kupfer beobachtbaren Defekten durchgeführt. Dabei zeigte sich, daß nahezu alle ausgewerteten Defekte am einfachsten durch Franksche Versetzungsringe vom Leerstellentyp zu erklären sind.
Scattering of Phonons at Defect Planes in the Simple Cubic Lattice
Authors: Ludwig W. , Pick H.
Published: July 2007

A discussion is given of the scattering of phonons in cubic crystals at (001)‐ and (011)‐defect planes (planes with impurity atoms, free surfaces and boundaries between two media) using a simple model. Reflection and transmission coefficients are calculated as functions of the wavevector and polarization of the incoming wave. The different forms of the scattering states are discussed.
Transmission Electron Microscopic Observation of Lattice Deformation in Antiphase Boundaries of Ordered Fe‐Si Alloys
Authors: Gemperle A. , Kočík J.
Published: July 2007

Transmission electron microscope studies of ordered Fe‐Si alloys show that a fringe contrast associated with antiphase boundaries appears in fundamental reflections. This effect is explained as being due to a deformation of the lattice by the boundary. The usual method employed in contrast experiments is used to find the direction of the additional displacement vector at the boundaries.
The Effect of Cadmium Additions on the Fracture Strength of Sodium Chloride Single Crystals
Authors: Harrison R. P.
Published: July 2007

The fracture characteristics of sodium chloride single crystals containing cadmium additions have been determined as a function of heat treatment and testing temperature. Precipitate particles reduce the fracture stress and strain at testing temperatures below −50°C. The results are related to other recent investigations into the mechanics of cleavage fracture in brittle solids.
Nuclear Magnetic Resonance and Mössbauer Effect Study of Sn119 in Rare Earth‐Tin Intermetallic Compounds
Authors: Borsa F. , Barnes R. G. , Reese R. A.
Published: July 2007

The nuclear magnetic resonance and Mössbauer effect of Sn119 have been studied in the cubic intermetallic compounds RSn3 (R = La, Ce, Pr, Nd, Sm, and Yb). Both the isotropic and anisotropic components of the Knight shift were determined in the temperature range 77 to 400°K. In the cases of PrSn3 and NdSn3 in which the shift measurements are proportional to the magnetic susceptibility, the results may be understood in terms of the Ruderman‐Kittel‐Kasuya‐Yosida theory, with an exchange interaction, T = −0.2 eV. The cases of CeSn3 and SmSn3 do not appear to be interpretable in terms of the RKKY theory. For PrSn3, NdSn3, and SmSn3 the Mössbauer effect of the Sn119 yielded a resolved quadrupole splitting of approximately 1.1 mm/s, independent of temperature in the range 4.2 to 300°K. The isomer shift was +0.70 mm/s, relative to Mg2Sn, also independent of temperature. The measured quadrupole coupling has been compared with that expected on the basis of the ionic model. No magnetic splitting was ever unambiguously observed, even at 1.5°K. Assuming that the magnetic splitting remains masked by the quadrupole interaction leads to an estimate of Heff ≦ 9 × 103 Oe in PrSn3 and NdSn3.
Disorder Resistivity and Spin Depolarization in Rare‐Earth Alloys
Authors: van De Braak H. P. , Caspers W. J.
Published: July 2007

Comparison of experimental results with the theory of the electrical resistivity of ferromagnetic rare earth alloys suggests a rapid redistribution of the scattered conduction electrons over the two spin orientations. In order to investigate whether this effect might be due to the Coulomb interaction between the conduction electrons, the mean free path for depolarization is calculated. In the Born approximation, the mean free path is of the order of some centimeters, whereas the mean free path for scattering is about 50 Å.
Influence of the Thermal Vibrations of the Crystal Lattice upon the Energy Distribution of Scattered Ions
Authors: Mashkova E. S. , Molchanov V. A. , Soshka V.
Published: July 2007

A study is made of the effect of thermal lattice vibrations on the energy spectra of ions scattered by a Ni crystal. The intensities of the double‐scattering peaks are found to decrease with an increase in the target temperature.
The Effect of a Magnetic Field upon Illuminated InAs p‐n Junctions
Authors: Mikhailova M. P. , Nasledov D. N. , Slobodchikov S. V.
Published: July 2007

A study is made of variations in photoresponse with strength of magnetic field in unbiased and reverse biased InAs p‐n junctions. This provides information on the combined effect of electric and magnetic fields, and illumination on p‐n junctions. The curves of photo‐electro‐magnetic e.m.f. against magnetic field strength for reverse biased p‐n junctions show linear inversion‐free regions. The results are analysed on the basis of the theory of the PEM effect in p‐n junctions.
Effect of State on the Shape of the Dislocation Rosette near an Indentation in Some Alkali Halide Crystals
Authors: Pariiskii V. B.
Published: July 2007

The structure of a dislocation rosette near an indentation in KBr and KCL crystals is studied. The motion of dislocations out of the rays of the dislocation rosette due to external impulse stress is shown to depend on the amplitude and duration of the pulse. The effect of stress on the shape of the dislocation rosette near the indentation is shown for KBR, KCI, and NaCI single crystals. During indentation of the stressed crystal the uniaxial surface contraction elongates the rosette rays that adjoin the direction of contraction, whereas the uniaxial dilation elongates the rays that adjoin the direction normal to the direction of extension. The effect is enhanced by increasing the preliminary stresses on the surface to be indented. The observed phenomenon is explained qualitatively by considering the structure of the rosette near the indentation. This effect may be used to determine the magnitude and sign of the local residual elastic stresses at the surface.
On the Theory of Surface and Impurity States
Authors: Levine R. D. , Amos A. T.
Published: July 2007

A formalism is developed for perturbation theory in which the Hamiltonian is resolved as H = H0 + V1 + V2 and the two perturbing potentials V1 and V2 are not treated in a symmetric fashion. All the operators are expressed in the H0 representation so that the formalism has particular applications in the theory of impurity states and surface and chemisorption states since H0 can be taken as that part of the Hamiltonian which acts on individual atomic sites, V1 the interatomic interaction and V2, which will have only a small number of non‐zero matrix elements, the effect of the surface or impurity atoms. These applications are illustrated using the linear chain as a model for a one‐dimensional crystal, and the present theory allows the results to be obtained in a very simple way.
Green's Function Method for Energy Band Calculations Including Spin‐Orbit Coupling
Authors: Treusch J.
Published: July 2007

The Green's function method proposed by Korringa, and Kohn and Rostoker, is modified to include spin‐orbit coupling. The formalism follows Korringa's work, and involves solving the two‐dimensional Pauli equation with the condition that the wave function be continuous. The computer time needed is comparable to the case in which spin is not included, as the structure constants are the same in both cases.
Transmission Electron Microscope Study of Brazil Twins and Dislacations Experimentally Produced in Natural Quartz
Authors: McLaren A. C. , Retchford J. A. , Griggs D. T. , Christie J. M.
Published: July 2007

Transmission electron microscopy has been used to examine single crystals of natural quartz which have been plastically deformed in compression at high temperature (500 to 700°C) and confining pressure (15 to 20 kbar) with high shear stress on (0001). In specimens deformed at 500°C, the only features found are closely spaced pairs of planar defects parallel to {0001}. Study of the diffraction contrast fringes reveals that each pair of defects bounds a Brazil twin band which has been produced by the high shear stress. At the higher temperature there are dislocations in the twin bands and other regions of the crystals with dislocations only. The dislocations are almost invariably either pure screw (b = a 〈1120〉) or of a particular mixed character (predominantly edge, but with a 30° screw component). Arrays of the mixed dislocations are observed which would produce stress fields consistent with the stress‐optical effects observed by optical microscopy.
On the Theory of Electro‐Absorption and Electro‐Reflectance in Semiconductors
Authors: Enderlein R. , Keiper R.
Published: July 2007

The dielectric response of a semiconductor in a static electric field is investigated. The dielectric function is found to be an integral operator. It should be possible to confirm experimentally the predicted generation of “harmonics” displaced with respect to the frequency of the incident light by an integer times the Zener oscillation frequency.
The Effect of Applied Electric Field on Diffusion of Impurities in Gallium Arsenide
Authors: Boltaks B. I. , Dzhafarov T. D.
Published: July 2007

Electrical migration of lithium and copper in gallium arsenide is studied. It is shown that lithium (between 740 and 980°C) and copper (between 820 and 1000°C) migrate in n‐type gallium arsenide as positive ions with a charge of less than +1. The decrease of the ionic charge is due to ion drag by the electrons. In heavily doped p‐type gallium arsenide, copper again migrates in the form of positive ions but in this case with a charge close to +1. This is due to the ion drag by the electrons being almost balanced by the drag from the holes which acts in the opposite direction. Experimental evidence suggests that thermal conversion in gallium arsenide is caused by copper diffusing from outside. Copper can be successfully removed from specimens by heating them in an applied dc electric field. Electrical migration of zinc and cadmium is also studied. Cadmium is shown to migrate in the form of positive ions. In the temperature range 830 to 1130°C, zinc also migrates as positive ions, the effective mobility decreasing with temperature. This temperature dependence of the mobility is in agreement with a theory of the ion drag effect.
Lattice Dynamics of MgO
Authors: Verma M. P. , Dayal B.
Published: July 2007

A phenomenological model developed by the author in an earlier paper [1] is applied to the case of MgO. The two‐phonon combined density of states (C.D.S.) is computed from the calculated frequencies. The C.D.S. peaks show good agreement with the subsidiary maxima in the infrared absorption spectrum of the solid. The calculated dispersion curves agree with Pekham's measurements except for the large wave‐vector region, and the specific heats agree with the experimental observations of Barron et al.
Polarization Vectors for Lattice Vibrations in Sodium
Authors: Björkman G. , Grimvall G.
Published: July 2007

The polarization vectors of the lattice vibrations in sodium are calculated for 46 points in the first Brillouin zone using Krebs's model.
The Pair Distribution Function in the R.P.A. and in the Hubbard Approximation
Authors: Brouers F.
Published: July 2007

The pair distribution function of the metallic electron gas is calculated exactly in the R.P.A. and in the Hubbard approximation. The results obtained are discussed and compared with those of previous approximate calculations and a slight modification to Hubbard's interpolation method is proposed.
Heat Capacity and Structure of Vitreous Silica and Diamond‐Like Lattices (I)
Authors: Tarassov V. V.
Published: July 2007

The phonon spectra of lattices with crystalline and glassy structures possessing skeletons of the purely covalent or ionic‐covalent type are discussed on the basis of the “one‐dimensional‐three‐dimensional model”. The upper frequency band, from ω′ to ωmax (ω′ ≪ ωmax), corresponds to a one‐dimensional frequency distribution g1(ω) in which elastic waves may propagate only in certain principal directions. In the lower band from 0 to ω′, the frequency distribution g3(ω) is three‐dimensional, as in the usual Debye‐Born‐von Karman theory. For the one‐dimensional distribution g1(ω) the exact solution is used and taken from papers by Pirenne and Renson, Deltour and Kartheuser for monoatomic and diatomic chains. The phonon spectrum for vitreous silica is discussed in terms of the present model, since its structure resembles that of β‐cristobalite. It is shown that the “chain model” applies to the thermal capacity of vitreous silica up to 900 °K.
Heat Capacity and Structure of Vitreous Silica and Diamond‐Like Lattices (II)
Authors: Tarassov V. V.
Published: July 2007

In a diamond‐like covalent lattice, and in vitreous silica, the phonon spectrum for the main high‐frequency band (containing 80 to 90% of all the modes of vibration) is one dimensional. This leads to the proposed chain model of Tarassov, Pirenne and Renson, and Deltour and Kartheuser. This model is used here to calculate the specific heat of germanium by using the data of Brockhouse and Iyengar. The same method is also applied to InP, AlSb, and vitreous silica.
X‐Ray Diffraction by Hexagonal Close‐Packed Crystals Containing Extrinsic Stacking Faults
Authors: Lele S. , Anantharaman T. R. , Johnson Ch. A.
Published: July 2007

The diffraction pattern for a hexagonal close‐packed (h.c.p.) crystal containing extrinsic stacking faults is derived under the assumption that the crystal is infinite in size with faults covering entire basal planes and distributed at random. While deformation faults broaden reflections with H – K ≠ 0 mod 3, L = 0 mod 2 and H – K ≠ 0 mod 3, L = 1 mod 2 equally and growth faults broaden the former twice as much as the latter, extrinsic faults are shown to broaden the latter only. The broadening due to extrinsic faults is symmetric without any shift of the peak position, as in the cases of deformation and growth faulting.
Die Beobachtung magnetischer Strukturen von Supraleitern zweiter Art
Authors: Träuble H. , Essmann U.
Published: July 2007

Durch Aufdampfen kleiner ferromagnetischer Partikel mit Durchmessern von etwa 100 Å auf Blei‐Indium‐Kristalle (χ = 1,2 bei 1,1 °K) wurde die magnetische Struktur im Mischzustand bei 1, 1 °K abgebildet und mit Hilfe von Abdruckverfahren elektronenmikroskopisch beobachtet. Unter günstigen Bedingungen liefert diese Methode ein Auflösungsvermögen von etwa 100 Å. Der magnetische Fluß dringt in diskreten Punkten mit einem Durchmesser von etwa 1000 Å durch die Probenoberfläche. Die Mehrzahl der Punkte ist in unregelmäßiger Weise zu Bündeln von etwa 30 Punkten vereinigt. Mit steigendem Feld nimmt die Zahl der Bündel zu und der Bündeldurchmesser ab. Identifiziert man die einzelnen Punkte mit Austrittsstellen einzelner Flußlinien, die jeweils ein Flußquantum tragen, so ergibt sich im Rahmen der zu erwartenden Genauigkeit befriedigende Übereinstimmung zwischen elektronenmikroskopischen Beobachtungen und gemessenen Magnetisierungskurven. Beobachtungen an dünnen Blei‐Indium‐Scheiben von 0,5 mm Dicke weisen auf die Existenz eines Zwischenzustands bei Supraleitern zweiter Art mit kleinem χ hin.
Conduction Band Structure of Cd0.1Hg0.9Te
Authors: Galazka R. R. , Sosnowski L.
Published: July 2007

The Hall coefficient RH and the conductivity σ are measured in the temperature range 4.2 to 300 °K. The thermoelectric power α as a function of the magnetic field and temperature are measured in the range 100 to 300 °K. The value of the effective mass mast; is calculated from these measurements for electron concentrations from 6.25 × 1016to 2.71 × 1018cm−3. The dependence of the effective mass mast; on k is interpreted according to Kane's model of the conduction band structure. The best agreement is obtained for values of the parameters ε0 = εΓ6 – εΓ8 = −0.00 eV and the coupling constant Q = 12 eV, that is for a linear ε vs. k dependence. The mobility of the electrons as a function of concentration and temperature is also analyzed. For temperatures below 77 °K impurity scattering is dominant. Within the temperature range 77 to 300 °K the best agreement between theory and experiment is obtained for mixed ionic and optical phonon scattering.
EPR Investigations on Mn2+‐Doped LiF Single Crystals
Authors: Böttcher R. , Windsch W. , Lüdke W.
Published: July 2007

A discussion is given of the EPR spectra of Mn2+ in LiF single crystals doped with MnF2 both in the melt, and by diffusion. There are two complexes, having orthorhombic and axial symmetry respectively. An explanation is given of the super‐hyperfine structure. It is shown that diffusion of Mn2+ ions into LiF single crystals can occur, and that the behaviour of such diffused ions is largely similar to that of ions incorporated into the crystal in the melt.
Röntgenographische Messung der charakteristischen Debye‐Temperatur bei vielkristallinem Silber mit Anwendung der Korrektur auf primäre Extinktion
Authors: Šedivý J. , Šíachová H.
Published: July 2007

Die Debye‐Temperatur Θ von polykristallinem Silber wird aus Röntgenstrahlenbeugungsmessungen bestimmt, die nur bei Zimmertemperatur durchgeführt wurden. Die Methode (unter der Bezeichnung „single‐temperature method”︁ bekannt) beruht auf einer relativ genauen Korrektur der ursprünglichen Extinktion. Sechs auf verschiedene Weise präparierte polykristalline Silberproben wurden untersucht. Der Mittelwert aus diesen Messungen ergibt einen Wert für Θ von (220 ± 8) °K. Die Differenzen zwischen den Θ‐Werten der verschiedenen Proben werden diskutiert, wobei berücksichtigt wird, daß jede Probe zehnmal untersucht wurde.
On the Phenomenon of Selenium Vitrification
Authors: Dzhalilov S. U. , Rzaev K. I.
Published: July 2007

The temperature range for the vitrification of selenium (18 to 36 °C) is determined from volumetric measurements. This is correlated with that obtained from data on the temperature dependence of the viscosity (the function aT), the specific heat, and the velocity of propagation of ultrasonic waves in selenium. It is shown for the first time that the vitrification temperature Tg of selenium depends on the experimental time base. A drop in the cooling rate of two orders of magnitude (from 0.5 to 0.005 deg/min) cause the Tg value to be decreased by 9 °C. Increasing the concentration of Te in selenium lowers the vitrification temperature of the SeTe co‐polymer according to a linear relation. The vitrification temperature of the specimen increases linearly with the concentration of Sb in selenium. This is explained as being due to the binding action of Sb, which consists of the formation of chemical cross‐links between the selenium molecules.
Anhysteretic Magnetization of a Collective of Magnetic Single‐Domain Particles
Authors: Straubel R.
Published: July 2007

A theoretical study is made of an ensemble of uniaxially anisotropic, completely aligned single‐domain particles, in which the particles are arranged in linear chains with positive or negative interaction. It is shown that the ensemble is in a true energetic equilibrium with small dc fields after an anhysteretic magnetization process. In this case the ensemble corresponds to an Ising‐model of equivalent spin arrangement. Hence the anhysteretic remanence curve of the ensemble in its initial part, and the anhysteretic initial susceptibility of both types of interaction are estimated.
On Stacked Screw Dislocation Arrays in an Anisotropic Medium
Authors: Chou Y. T.
Published: July 2007

A direct method is presented for finding the distribution of dislocations in uniformly stacked arrays in an anisotropic medium. A simple procedure for evaluating the stress field is given. The analytic technique is applied to a special case of an infinite sequence of identical double‐ended pile‐ups stacked one above the other. In this case, the number of dislocations in each of the pile‐ups is found to be less than that in an isolated pile‐up and decreases continuously as the separation between pile‐ups decreases. The stress concentration around the tips of each array behaves in a similar manner. It is shown that the system is elastically equivalent to a vertical array of parallel shear cracks.