bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electrical and optical properties of CuGaTe2
Authors: Hörig W. , Kühn G. , Möller W. , Müler A. , Neumann H. , Reccius E. 
Published: July 2007

AbstractThe electrical and optical properties of CuGaTe2 single crystals were investigated by resistivity and Hall effect measurements in the temperatur range T = 77… 300 K and optical transmission measurements in the temperature range T = 20… 300 K at photon energies hν = 1.15…1.50 eV. All samples were p‐type conducting due to shallow acceptors with ionization energies EA1 ≈︁ 10−3 eV and concentrations NA1 ≈︁ p = (2…4). 1018 cm−3. The absorption spectra could be described by simultaneous consideration of acceptor ‐ to ‐ conduction band transitions with EA2 = 360 meV and NA2 ≈︁ 1022 cm−3 and valence band ‐ to ‐ conduction band transitions with EG = 1.24 eV at room temperaure. The temperature coefficient of the fundamental edge is dEG/dT = −4.0. 10−4 eV/K. The results are discussed with regard to some general trends found in the Cu‐III–VI2 compounds.
Modelle und Eigenschaften von Korn‐ und Phasengrenzen
Authors: Goux C. 
Published: July 2007

AbstractEs sind Strukturmodelle für Korngrenzen in reinen Metallen, in Legierungen und für Phasengrenzen zwischen zwei Kristallen unterschiedlicher Elemente bekannt. Geometrische und energetische Vorstellungen dazu werden diskutiert. Mit einer energetischen Methode wird versucht, die Struktur von Korngrenzen zu bestimmen. Die Ergebnisse der theoretischen Arbeiten sind geeignet, die Deutung experimenteller Ergebnisse an orientierten Bikristallen zu fördern. Die direkte Untersuchung des Korngrenzeneinflusses auf die Eigenschaften von Vielkristallen bleibt aber eine Notwendigkeit.
Surface structures of fluorite crystals
Authors: Desai C. C. 
Published: July 2007

AbstractOptical studies have been made of the microstructures on the natural {100} and {111} faces of natural fluorite crystals. The protrudance of triangular elevations, growth pyramids, and natural etch pits have been observed on a large number of crystals. It is suggested that fluorite crystals grown by two‐dimensional spreading and piling of growth layers parallel to {100} faces. The natural etch pits on {100} and {111} faces suggest that they have been produced as a result of a dissolution process in nature. The natural faces have been etched in the laboratory and it is established that the pits indicate the existence of linear defects in the crystals. The implications are discussed.
Growth and electrical properties of epitaxial CuInS2 thin films on GaAs substrates
Authors: Neumann H. , Schumann B. , Peters D. , Tempel A. , Kühn G. 
Published: July 2007

AbstractCuInS2 thin films with thicknesses in the range of 500 Å were deposited onto semi‐insulating (111) A‐oriented GaAs substrates by flash evaporation in the substrate temperature range Tsub = 570 … 870 K. Epitaxial growth begins at Tsub = 645 K. The films had always the chalcopyrite structure. Indications to a transition from the chalcopyrite phase to the sphalerite phase were observed at Tsub = 870 K. Films grown at Tsub ≦ 800 K showed n‐type conductivity whereas at growth temperatures Tsub ≧ 850 K the films were always p‐type conducting. A donor level and an acceptor level with ionization energies of 0.24 eV and 0.22 eV, respectively, were found from an analysis of the electrical measurements.
Growth of USb2 single crystals and their structural perfection
Authors: Henkie Z. , Misiuk A. 
Published: July 2007

AbstractUSb2 single crystals were grown by three methods; I — Chemical vapour transport with iodine as transporting reagent, II — Crystallization from USb liquid solution, III — Crystallization from USbSn liquid solution. The morphology of growth and results of X‐ray topography examination of crystal surface are given.
Zur Morphologie organischer Kristalle mit zwei Molekülen in der asymmetrischen Einheit. Ein Beitrag zur Korrespondenz von Kristallstruktur und Habitus
Authors: Follner H. 
Published: July 2007

AbstractIn einer vorangegangenen Arbeit wurde gezeigt, daß Pseudosymmetrien die Kristalltracht organischer Kristalle beeinflussen. Das morphologische Gitter von Strukturen mit zwei kristallographisch unabhängigen Molekülen in der Elementarzelle entspricht dem Gitter der Zentren zwischen beiden Molekülen. Dies kann mit Hilfe „morphologischer Auslöschungsregeln”︁ nachgewiesen werden.
Determination of Nitrogen Concentration in GaP Epitaxial Layers by Two Independent Methods
Authors: Hänsel T. , Brühl H.‐G. , Bindemann R. , Seifert W. , Jacobs K. 
Published: July 2007

AbstractThe nitrogen concentration in GaP is determined by optical absorption in the A‐line at T = 77 K. The concentration of the isolated nitrogen atoms is given for T = 77 K by the modified LIGHTOWLERS' relation [NA] cm−3 = 8.2 · 1014 phαmax, where α is measured in cm−3, h in meV. p is a dimensionless line shape factor. It is shown that at higher N concentrations considering only the A‐line absorption the impurity density is underestimated because the nitrogen atoms included in NNi pairs give no contribution to the absorption. The measurements have been made in the range from [N] = 5 · 1016…︁ 1019 cm−3 in layers grown by vapour phase epitaxy. The results are compared with nitrogen concentrations obtained by precision lattice parameter measurements. The change of the lattice parameter is calculated using VEGARD's law. The good agreement between the nitrogen densities obtained by two different independent methods reveals (i) that the LIGHTOWLERS' calibration factor is valid also at higher N‐concentrations and (ii) that the nitrogen atoms are predominantly incorporated into P‐lattice sites.
Effects of Environmental Gas on HVEM Radiation Damage in Aluminum
Authors: Jesser W. A. , Imura T. , Nohara A. , Nishino Y. 
Published: July 2007

AbstractAluminium was irradiated by 1000 keV electrons in an environmental cell either evacuated or containing 2.7 kPa (20 torr) of hydrogen or air. The resultant dislocation loop density was altered by the presence of air but not by the presence of hydrogen. These results are consistent with the idea that environmental gas alters the strength of the free surfaces as sinks for point defects.
In‐situ Observations on Cu‐SiO2 and Stainless Steels
Authors: Brooks J. W. , Haque E. , Loretto M. H. , Smallman R. E. 
Published: July 2007

AbstractSpecimens of CuSiO2 and of several high purity stainless steels have been observed during deformation in an HVEM. The behaviour of the CuSiO2 specimens is dominated by the free surfaces, even in the thickest regions which can be examined, but in the stainless steels it has been found that if the specimen is thicker than about 0.5 μm, bulk behaviour is observed. The formation of ϵ‐ and α‐martensite has been directly observed and essentially identical observations of martensite formation have been made during cooling. It has been shown that ϵ‐martensite is always formed in regions where appropriately, but usually irregularly spaced faults, are generated and detailed analyses of isolated and overlapping faults show that these faults contain close‐packed planes of the appropriate eph spacing. α‐martensite is formed in association with dislocation pile‐ups.
Subgrain structure formation in pure crystals grown from melts
Authors: Tsivinsky S. V. , Maslova L. A. 
Published: July 2007

AbstractThe arrangement of low‐angle boundaries and the subgrain structure of crystals with high (≧ 105 cm−2) dislocation density are considered. Relations to estimate cross dimensions and misorientations of nucleating subgrains are derived. Production conditions for single crystals without nucleating low‐angle boundaries are described and relations to estimate the critical dislocation density, below which subgrain nucleation is highly improbable, are supplied. Macrosubgrain formation mechanisms are described. Growing conditions for crystals free of macrosubgrains are formulated. Equations to estimate their cross dimensions and misorientations are proposed. These are compared with the available experimental data for a variety of materials.
Properties of oriented TTF‐TCNQ thin films
Authors: Reinhardt C. , Vollmann W. , Hamann C. , Libera L. , Trompler S. 
Published: July 2007

AbstractVapour deposited thin films of the organic molecular complex tetrathiafulvaliniumtetracyanoquinodimethane (TTF‐TCNQ) are investigated by electrical and electronmicroscopical methods. Morphology studies by means of electron micrographs show, that the thin films up to thicknesses of 300 nm consist of small crystals of a size of 1.2 · 0.2 μm2 (deposited on cleaved (100) faces of NaCl) or 15 · 2 μm2 (on glass substrate). Dependend on deposition conditions and on material of the substrate thin films are produced with strong or statistic orientation of this crystals. Strong oriented thin films exhibit conductivities up to σ = 65 ω−1 cm−1 and activation energies of WA = 0.02 eV. The found dependences of the conductivity on electrical field strength. temperature, and size of microcrystals are explained by a linear hopping model.
A simple numerical method for the simulation of the (GaIn)P liquid phase epitaxy process
Authors: Penndorf J. , Kühn G. 
Published: July 2007

AbstractOn the basis of the solution of the diffusion equation for step‐cooling and uniform cooling accomplished by RODE a numerical procedure is derived for the LPE process. The dependence of the diffusion coefficient and the slope of the liquids curves on temperature and chemical composition in the ternary system have been taken into account by an empirical approach. Effects of nucleation and evaporation of phosphorus at growth temperature are considered by dividing the diffusion space. The dependence of layer thickness on growth time and the compositional variation of the grown layers are calculated and compared with the experimental results.
Plastic strain and dislocation structure of the KDP group crystals
Authors: Guin Chan Hai , Katrich M. D. , Savinkov A. I. , Shaskolskaya M. P. 
Published: July 2007

AbstractPlastic strain of the KDP, DKDP, RDP, ADP crystals has been studied by the methods of uniaxial compression, selective etching, and indentation. It has been found that at room temperature the crystals had little plasticity, while at high temperature their plasticity was large. Rows of dislocations and dislocation rosettes have been observed. Glide systems and activation parameters of the process of plastic glide have been determined.
AlxGa1−xAs LPE growth
Authors: Nevsky O. B. , Noghinov A. L. , Kuznetsov Ju. N. 
Published: July 2007

AbstractAlxGa1−xAs LPE growth was studied within the temperature range of 930–900°C with Al concentrations in solutions from 0.04 to 2.4 at.%. AlAs concentration in layers has been shown to grow with the cooling rate increase of solution. Interface and volume nucleation parameter dependence of Ki and Kv and formation time tf on Al concentration in Ga solution have been found. Addition of Al to Ga solution increases critical values of As supersaturation (supercooling) and, as a result, increase in thickness of AlxGa1−xAs layers compared with GaAs layers have been determined in spite of As concentration lowering in Ga solution.
Measurements on anisotropy of angular distribution for the backscattering electron emission on copper monocrystals
Authors: Bauer H.‐D. 
Published: July 2007

AbstractDuring the perpendicular bombardment with 25 keV primary electrons the azimuthal and polar angular distribution are measured of those backscattered electrons which escape from the low index surfaces of a copper monocrystal. A movable electron spectrometer operates as a detector with the energy resolution of ΔE/E ≈ 10−3 and the angular resolution of Δθ = 0.5°. The observed angular distribution proves congruously with large angle Kikuchi reflection diagrams, the representation of which at metallic surfaces was successful as yet only for oblique incidence. The connection between escape direction and energy loss and also the influence of covering layers are investigated.
Dynamics of twin layer widening in In‐Pb crystals
Authors: Lubenets S. V. , Fomenko L. S. 
Published: July 2007

AbstractThe authors studied mobility of boundaries of plane‐parallel twin layers in In‐0.2 wt.% Pb and In‐2 wt.% Pb crystals in the temperature range 290–373 K when stresses are applied τ/G = (1.35 – 7) × 10−6 (G is the shear modulus). They found that lead concentration increase as well as dislocation structure deterioration result in lower boundary velocity for a constant stress.In In‐2 wt.% Pb crystals, the boundary velocity is well describable as Vn = V0(τ) × × exp [ − ΔH (τ)/kT] where V0(τ) = Aeατ/G (A = 10−3 cm/s, α = 1.1 × 106) τ ΔH(τ) is the activation energy depending on the stress, ranging under these circumstances from 0.33 to 0.43 eV.At present it is difficult to interpret the results at hand. The analysis allows only to assume that the change in the boundary movement activation energy for impure crystals as against that for pure ones can be associated with the impurity effect on the structure of the intermediate zone between the twin and the matrix. The dependence of the pre‐exponential factor on the stress is probably due to the effect of the internal long‐range stress field on sources of twinning dislocations.Comparison with data for calcite and pure indium shows that twin boundary mobility parameters and their dependence on the stress are governed by the crystal type and defect structure.
Observations on the growth of NiMoO4 crystals in Silica gel media
Authors: Kurien K. V. , Ittyachen M. A. 
Published: July 2007

AbstractGrowth of NiMoO4 crystals by gel method has been described. By manipulating the condition of growth parameters, crystals of fairly large dimensions have been obtained at ambient temperature. The crystal faces are examined by optical and scanning electron microscopy and thus a two‐dimensional layer growth mechanism for the development of the faces have been proposed.
The molecular and crystal structure of p‐methyl‐phenyl glyoxylacid‐m‐trifluoro‐anilide
Authors: Hoehne E. , Seidel I. 
Published: July 2007

AbstractUsing X‐ray crystal structure analysis of the title compound the positions of all atoms (including all A atoms) were localized in the triclinic unit cell with the parameters a = 14.686 Å, b = 7.700 Å, c = 7.898 Å, α = 122.5°, β = 105.4°, γ = 87.7°, space group P1. The existence of an intramolecular HN … O(1) bridge was inferred, the H‐bridge acceptor of which predominantly is the π‐electron density of the carbonyl group in agreement with the results of the X‐ray crystal structure analysis of p‐methyl‐phenyl‐glyoxyl‐acid‐p‐chloroanilide (HOEHNE, SEIDEL). Moreover, the existence of H‐bridgelike interactions of the two phenyl hydrogen atoms H(6) and H(15) to the carbonyl oxygen O(2) could be proved. These interactions stabilize the conformation of the two phenyl rings in the molecule.
The crystallisation of chromite‐magnesiochromite spinels from a calcium magnesium aluminosilicate glass: Nucleation, crystal growth and final crystal sizes
Authors: Packter A. , Robson M. J. 
Published: July 2007

AbstractThe crystallisation of chromite‐magnesiochromite spinels was studied from a calcium magnesium aluminosilicate glass (a simulated slag) containing 3 to 12 percent total iron oxides and 0.3 to 1.5 percent chromium(III) oxide, at temperatures from 1400° to 700 °C. – Spinel crystallisation occurred in glasses with 3–7 percent FeO and 0.7–1.1 percent Cr2O3. At temperatures 1100 °C and above, the nucleation was rapid and crystal numbers very high, at FeO contents above 3 percent and Cr2O3 contents above 0.7 percent; at 1056° and 1000 °C however, the crystal numbers reached some optimum values but then decreased as clinopyroxene crystals grew onto and enveloped the spinel microcrystals. In these glasses, the crystal lengths varied with growth time according to the relation, lt = 2 kg tα = Rg1 tα, where α = 0.7–1.0: this time dependence was a compromise between a relation for dendritic growth and one for facetted growth. The growth rates generally increased about five to seven times for 160 °C temperature rise: the energy of activation for the spinel crystal growth was then estimated as 180 ± 60 kJ mole−1. – No spinel crystals were observed in glasses with more than 7 percent FeO content, only clinopyroxene crystals. Probably, these latter had nucleated rapidly and grown onto spinel microcrystals, while the spinel microcrystals were still of < 0.1 μm size.
Epitaxial growth of GaN on {1012} oriented sapphire in GaCl/NH3/He and GaCl/NH3/H2 systems
Authors: Fitzl G. , Tempel A. , Seifert W. , Butter E. 
Published: July 2007

AbstractGaN epitaxial layers were grown on {1012} sapphire substrates in the systems GaCl/NH3/He and GaCl/NH3H2, respectively. The films obtained were investigated by light microscopy, RHEED method and electron‐microscopical replica technique. The epitaxial relationship was found to be {1012} // {1120}GaN; 〈1120〉 // 〈1010〉GaN With respect to layer perfection the temperature range of 800 … 1060°C and growth rates ≧ 1 μm/min are the best growth conditions.
The precipitation of sparingly‐soluble acid, neutral and basic metal salts from aqueous solution: Ionic equilibria at different pHs, precipitate phases and precipitation mechanisms
Authors: Packter A. 
Published: July 2007

AbstractThe precipitations of the sparingly‐soluble acid, neutral and basic salts of the divalent cations beryllium, magnesium, calcium, strontium, barium, manganese (II), iron (II), cobalt (II), nickel (II), copper (II), zinc, cadmium, mercury (II), tin (II) and lead (II) with the inorganic anions sulphate, chromate, molybdate, monohydrogen phosphate, phosphate, and carbonate (from supersaturated aqueous solutions) are surveyed. The different types of ionic equilibria (cation hydrolysis, anion hydrolysis, ion‐pair formation) that may influence these precipitations, at different pHs and ionic concentrations, are examined. The crystalline phases precipitated at different pHs are tabulated and the precipitation mechanisms (at different pHs) are analysed.
On the occurrence of polytypism in single crystal CdTe thin films
Authors: Tiwari Brajesh Kumar , Srivastava O. N. 
Published: July 2007

AbstractCadmium telluride thin films have been found to exhibit polytypism. The polytypes are formed when the as grown amorphous CdTe thin films undergo amorphous to crystalline transformation. The transformed single crystal regions correspond to different polytypes. Besides the well known zinc blende type 3 C cubic phase and less often found wurtzite type 2 H phase, four new polytypes (5 H, 6 H, 6 R and 15 R) the only ones known to‐date have been found in the present investigation. In addition to the new polytypes, a new structural variant has also been found. This has the same ‘c’ parameter as that of the 2 H phase but has its ‘a’ lattice parameter as ‘a0 \documentclass{article}\pagestyle{empty}\begin{document}$ a_{\rm o} \sqrt {3} $\end{document}’ (a0 being the common lattice parameter of the polytypes). A feasible mechanism making the formation of polytypes intelligible has been suggested.
The effect of dynamic recrystallization on the growth velocity of new phase crystals at polymorphic transformation of tin and thallium
Authors: Brick V. B. , Larikov L. N. 
Published: July 2007

AbstractThe analysis of dynamic recrystallization influencing the crystal growth of the new phase in high purity tin and thallium (99.9995%) is carried out. It is shown that in tin, in which the β → α transition proceeds on the dislocation or the normal mechanisms (depending upon a supercooling degree, ΔT) a superposition of dynamic recrystallization results in an increase of the growth velocity of α‐Sn crystals. The most distinct of acceleration is observed at −21 ÷ − 23 °C, when the growth velocity of recrystallization centers and the maximal growth velocity, Vmax, of the crystals are comparable values. The dynamic recrystallization superposition in thallium offers to transform the transformation mechanism. Thereby an erase of the features of the martensite α ⇄ β transition mechanism and an appearance of the features of the normal crystal growth mechanism of the new phase are observed.
The structure of CuCd alloys obtained electrolytically on monocrystal copper cathodes
Authors: Łagiewka E. 
Published: July 2007

AbstractTests were made on the structure of CuCd alloys obtained on single crystal copper cathodes with surfaces parallel to the (111), (110) and (100) planes. X‐ray phase identification indicated the presence of α‐phase in the form of a solid solution of cadmium in copper. In the low cathode potentials range alloy crystallite orientation is governed by twinning on the {111} planes of crystallites of epitaxial orientation relative to cathode surface. The surface morphology of alloys obtained up to potential −490 mV depend on cathode type. Above this potential value alloy surface morphology is determined by potential at which it is obtained.
EPR spectra of irradiated Na2Cr2O7 · 2 H2O crystals
Authors: Alybakov A. A. , Gubanova V. A. , Tojchiev N. 
Published: July 2007

AbstractThe EPR spectra of X‐irradiated Na2Cr2O7 · 2 H2O crystals grown from the aqueous solution at room temperature are studied. Three groups of lines are detected, which marked conventionally as C1, C2 and C3. Each of the C1 and C2 line groups is a superposition of two doublets. The lines are interpreted as due to the Cr5+ ions in the distorted (stretched) oxygenous tetrahedron. The doublet structure is due to hyperfine interaction with nuclei of 1/2 spin which are protons of water. It is shown that the C1 and C2 line groups are due to the centers of the same type with different orientations in the lattice. The principal g‐tensor values for these centres were as follows: gz = 1.916, gy = 1.978, gx = 1.986.
Crystal and molecular structure of piperidinium‐acet‐p‐Cl‐anilide‐bromide
Authors: Reck G. 
Published: July 2007

AbstractThe crystal structure of piperidinium‐acet‐p‐Cl‐anilide‐bromide is monoclinic, space group P 21/n with 8 formula units C13H18N2OBrCl in the unit cell. The lattice constants are a = 7.337(2), b = 17.865(4), c = 22.822(5) Å, and β = 94.66(1)°. The title compound is not isomorphous to the corresponding chloride. Br ions are linked to the molecules by hydrogen bonds forming chains in the crystal structure.
Studies on the preparation and characterization of the Ce2(SO4)3 · 8(H, D)2O
Authors: de Saja A. , Rull F. , Pastor J. M. , de Saja J. A. 
Published: July 2007

AbstractCerium Sulfate octohydrate crystals were crystallized from aqueous solutions under controlled conditions. The solubility measurements were carried out on temperatures between 10 and 80°. Thermoanalytical methods were applied for the study of the thermal behaviour of this compound. Raman spectra of polycrystalline Ce2(SO4)3 · 8H2O and Ce2(SO4)3 · 8D2O recorded at 80 K are reported. The vibrational modes have been assigned by comparing the spectrum of both compounds and using structural considerations.
TEM Investigations of the Influence of Strain Rate and Mode of Deformation on the Substructure of an Fe‐Ni‐C alloy
Authors: Martin U. , Hensger K.‐E. , Klimanek P. 
Published: July 2007

AbstractThe influence of strain rate and mode of deformation on the substructure of a Fe‐Ni‐C alloy was estimated by TEM. The softening processes during hot deformation appear as dynamic recovery and dynamic recrystallization. – The dynamic recrystallization is favoured by increased strain rate and one‐dimensional state of stress.
Energy levels of dislocations in Ge under different conditions. Comparison between images of electron‐ and light‐beam scanning microscopy
Authors: Castaldini A. , Cavallini A. , Gondi P. 
Published: July 2007

AbstractThermal treatment effects on Ge deformed at 350°C are consistent with reductions of the effective dangling bond densities on the dislocations. On account of difficulties in the application of known statistics the phenomena observed are briefly discussed by considering a heavily doped cylinder model for the dislocations. Observations with infrared beam induced currents emphasize the necessity of considering the effects of other defects, introduced together with dislocations during deformation, in particular for the interpretation of photoconductivity data.