bluuebunny/crossref_metadata_2025_split huggingface dataset:
Magnetic phase transitions in LaMnO3+λ
Authors: Pavlov V. I. , Bogush A. K. , Balyko L. V. 
Published: January 2007

AbstractMagnetic properties of nonstoichinometric lanthanum manganite LaMnO3+λ as a function of the Mn4+ concentration (from 0 to 27%) and temperature (from 77 to 300 K) are investigated. The Mn4+ ions concentration depends on the degree of oxidation λ. It is shown that at 0–10% Mn4+ there exists an antiferromagnetic ordering and at 10–14% — mixed ferro‐antiferromagnetic ordering, while at Mn4+ concentration exceeding 14% the ferromagnetic ordering takes place. The concentrational antiferromagnetic‐ferromagnetic transition at 14% Mn4+ is due to the crystal structural O' — O orthorhombic transition. In ferromagnetic O‐orthorhombic lanthanum manganite the phase ferromagnetic‐paramagnetic transition occurs via intermediate magnetic state where in the paramagnetic matrix there are noninteracting ferromagnetic impurity clusters. The presence of such magnetic state gives rise to anomalous behaviour of magnetic and galvanomagnetic properties of LaMnO3+λ near Curie temperature.
The coprecipitation of Magnesium Nickel Oxalate Dihydrate Powders (solid solutions) from aqueous solution: Precipitate compositions and Cporecipitate Mechanisms
Authors: Packter A. , Omomo A. 
Published: January 2007

AbstractThe coprecipitation of magnesium nickel oxalate dihydrates from mixed metal cation solutions was monitored by conductivity measurements. A series of coprecipitates was then prepared from 0.2 M solutions with Mg contents varying from 0.2 to 0.9 total metal cation and their compositions and structures studied by chemical analysis, infra‐red spectrophotometry, thermogravimetric analysis and detailed differential calorimetry. The coprecipitates with upto 20 percent Mg content were solid solutions with structures similar to nickel oxalate dihydrate, the coprecipitates with 20 to 80 percent Mg content were probably mixed solid solutions while the coprecipitates with over 80 percent Mg content were solid solutions with structures similar to magnesium oxalate dihydrate.The ionic equilibria in supersaturated magnesium nickel oxalate solutions were analysed and mechanisms are proposed for coprecipitations from solutions of different Mg/(Mg + Ni) ratios.
Formation of space‐charge electric field and space charge during the cleaving of Alkali Halide Crystals
Authors: Gromov V. V. , Rozno A. G. , Romanov A. V. 
Published: January 2007

AbstractThe “acoustic probe” method has been used for the measurement of the space‐charge and polarization in the crystals LiF, NaF, KCl and NaCl exposed to mechanical action. It has been shown that large mechanical stresses in the bulk of crystals lead to the formation of space‐charges and inhomogeneous polarization. The reason for this phenomenon is, probably, the motion of dislocation pile‐ups.
On facets existed on concave interfaces in Czochralski‐grown GaSb crystals
Authors: Kumagawa Masashi , Hayakawa Yasuhiro 
Published: January 2007

AbstractIt is tried to make facet regions grow on interfaces curved concavely toward the melt using the Czochralski method. By increasing rapidly the pulling rate of crystals, the whole growth interface is once remelted and a concave interface is formed in the following growth process. A facet region occurs from a (¯I¯I¯I) plane which appears by the remelt of interfaces. This facet continues to grow while it is being surrounded by concave interfaces of nonfacet regions. From the microscopic measurement of spreading resistance. the impurity concentration is higher in the facet region than in non‐facet ones. This suggests that the growth mechanism of the facet on concave interfaces is the same as that on convex ones.
Double crystal topographic investigations of PbTe grown by the travelling heater method (THM)
Authors: Winkler M. , Genzel C. , Parthier L. , Gille P. 
Published: January 2007

AbstractTHM‐grown PbTe and PbTe: Tl were examined near the (n, —n)‐position by means of X‐ray double crystal arrangement. The half‐width of the rocking curves of Tl doped PbTe is larger than that of undoped PbTe by factor two. Long range and local lattice plane distortions, as well as disturbances induced during preparation, in the from of dislocation slip lines and greatly disoriented areas were observed.
X‐ray triple‐crystal diffractometer investigation of arsenic implanted silicon after pulsed laser irradiation
Authors: Zaumseil P. , Winter U. , Galler R. 
Published: January 2007

AbstractX‐ray triple‐crystal diffractometry (TCD) of parallel (+n, ‐n, +n) setting was used to investigate the structural changes of silicon surface layers after arsenic implantation and pulsed laser irradiation. The implated layers of different doses show enlarged lattice constants in the disturbed crystalline parts. After low energy annealing a polycrystalline surface layer is built up from the amorphous layer while the crystalline layer below it is not significantly changed. High energy annealed regions show recrystallisation with high degree of perfection and decreased lattice constant. The results of TCD measurements are compared with results of double‐crystal diffractometer investigations and advantages of the TCD method are discussed.
The structure of Dimethylaminomethanediphosphonic Acid, C3H11NO6P2
Authors: Kulpe S. , Seidel I. , Szulzewsky K. 
Published: January 2007

AbstractMr = 218.9, monoclinic, P 21/c, a = 6.870(1), b = 10.824(2), c = 11.337(2) Å, β = = 94.59(2)0, Z = 4, V = 840.5(3) Å3, Dx = 1.73 Mgm−3. Final R = 0.033 for 2648 independent reflections, excluding those with |F0| < 3σ(F0). Intensities were measured with an automatic diffractometer. This organophosphorous compound is characterized by two PC bonds. Four symmetrically independent intermolecular hydrogen bonds determine the threedimensional packing of the molecules and the unique chemical properties of the campound.
Radiation‐controlled enhancement of electroluminescence in Calcium Sulphide Electroluminors
Authors: Bhushan S. , Chandra F. S. 
Published: January 2007

AbstractEnhancement and quenching effects in electroluminescent emission from CaS:Cu, Er and CaS:Cu, Sm electroluminors under the concurrent action of electric field (a.c. or d.c.) and radiation (3650 Å) has been investigated. Variation of the ration R defined by R = (BE+/BE + BL) has been studied as a function of voltage (a.c. or d.c.) and frequency (a.c.) of the applied field. The net effect is found as combination of enhancement and quenching. Sometimes peaks (one or more than one) are also found. With the increase in frequency of a.c. field higher value of R is found. No regular variation with increase in intensity of uv radiation is found.
Grain boundary migration in high‐temperature deformation
Authors: Gifkins R. C. 
Published: January 2007

AbstractObservations of grain‐boundary migration in both creep and fatigue are reviewed and grouped into thirteen classifications, particularly noting the relationship between migration and grain‐boundary sliding. It is concluded that all experimental observations so far have been of more than one of these classifications and none give unambiguous support to the hypothesis that sliding and migration are coupled through the motion of grain boundary dislocations. Several sets of results using bicrystals are particularly difficult to reconcile with this hypothesis.
Dislocation mobility in LiF at low temperatures
Authors: Suzuki Takayoshi , Nakamura Kazuo 
Published: January 2007

AbstractThe mobility of dislocations in LiF has been measured at 4.2 and 10 K by means of an etch pit technique. The average velocity of screw dislocations is 2–5 times as large as edge dislocations. The results of the stress and temperature dependence of the velocities correlate well with the data of the critical shear stress in the same temperature region, and are well described by the theory of Peierls mechanism with thd Peierls stress of about 20 MPa for edge dislocations on {110} slip plane.
Study of the instability boundaries of plastic flow in Cu + 14 at.% Al single crystals at low temperatures
Authors: Komnik S. N. , Demirski V. V. 
Published: January 2007

AbstractThe authors experimentally revealed the existence of the temperature‐strain rate region of jumplike deformation in Cu + 14 at.% Al single crystals between 4.2 and 25 K. For each particular temperature in this temperature range, there are a lower and an upper critical strain rates, between which deformation is jumplike. The character of transients occurring during strain rate variation was investigated by increasing the strain rate to the lower critical value. The experimental data are explained in terms of the thermomechanical instability concept and inertial effects of the sample‐machine system.
Fracture‐induced luminescence in Alkali Halides
Authors: Strube W. , Linke E. 
Published: January 2007

AbstractCrack propagation in dielectric solids is connected with many structural and electronic excitation processes. In order to obtain some information on the elementary excitation mechanism, crack velocity and fracture‐induced luminescence in LiF and NaF (as received; doped; X‐irradiated) under high vacuum conditions were correlated. Time‐resolved crack velocity measurements revealed the usually discontinuous manner of crack propagation; maximum crack velccities of 3800 m/s (LiF) and 3000 m/s (NaF) were observed. Luminescence excitation in the X‐irradiated samples occured at slow crack motion i.e. for increased plastic processes in the crack tip zone. The luminescence was explained by the recombination of stabilized radiation defects (F‐centres and interstitial halogen atoms) involving a radiative exciton decay. The recombination is triggered by the crack via mobilization of the recombination partners by dislocations or lattice deformation processes.
Crystal and molecular structure of (E)‐21‐Methoxycarbonyl‐19‐nor‐pregna‐4,8(14),20‐trien‐3‐one
Authors: Reck G. , Schubert G. 
Published: January 2007

AbstractThe crystal and molecular structure of the title compound has been determined by X‐ray diffraction techniques. It crystallizes in the orthorhombic space group P 212121 with cell parameters a = 12.662 Å, b = 17.995 Å, c = 8.433 Å. The structure was solved by direct methods using MULTAN‐78 and refined by least‐squares calculations to the conventional R = 0.061. The ring conformations of the steroid skeleton and the 17β‐side chain conformation are discussed in detail.
The mechanism of the rotation of single‐crystal spheres during sintering
Authors: Wieters K.‐P. , Boiko I. J. , Schatt W. 
Published: January 2007

AbstractA dislocation mechanism is presented which explains the fast rotation of particles as observed during the sintering of rows and loose packings of monocrystalline copper spheres. The experimentally determined data agree well with the data determined by calculation. They are important for the production of sintered filters.
Solid‐phase epitaxy for the formation of superlattices based on A3B5 compounds
Authors: Sheftal R. N. 
Published: January 2007

AbstractTo form superlattices based on A3B5 compounds, it is suggested to use solid‐phase epitaxy (SPE) which includes recystallization of super‐thin films of stoichiometric composition deposited by laser evaporation on single‐crystal plates or films with the same or close composition. The recrystallization temperature is shown to be reduced considerably for the film grains with its curvature differing significantly from zero and which are in contact with their own single‐crystal seed having practically zero curvature. The single‐crystal multilayer films GaAs‐(Al, Ga)As … GaAs were formed at 300°C. The recrystallization rate at this temperature was 40 Å/min. The autocatalytic action of the single‐crystal seed strongly reduced the activation energy of the SPE process, which may be due to diffusion in solid phase.
Structure sensitivity of relaxation phenomena in NaCl and KCl crystals doped with some divalent impurities [I] ITC‐spectra characteristic of the as‐cleaved state
Authors: Suszynska M. , Capelletti R. 
Published: January 2007

AbstractITC spectra of NaCl and KCl crystals doped with europium, lead, and nickel (in a wide concentration range) have been measured at temperatures between 120 and 400 K. It has been shown that the spectra taken for as cleaved samples are usually very rich. The origin and behaviour of the high‐temperature peaks (above the IV‐dipole peak) have been discussed in frames of the SILLARS theory of Maxwell/Wagner‐type polarization effects in heterogeneous dielectrics. It is suggested that the peak positioned near room temperature is related with any type of vacancy rich precipitates formed within otherwise homogeneous crystal lattice. The second peak, positioned at still higher temperatures, is a Maxwell/Wagner effect due to dislocations surrounded by impurity‐related imperfections in a fashion of the so called Cottrell atmosphere.
Shaped crystal growth of PbTe by the open tube technique
Authors: Klimakow A. M. , Höfer Ch. 
Published: January 2007

AbstractThe possibility of growing shaped AIVBVI crystals from the vapour phase by the open tube technique was investigated on PbTe. The thermodynamic conditions to reproducible prepare several habits of PbTe crystals — whiskers, tetrahedral prisms and cubes, platelets (a), dendrites, cubic and octahedral skeletons (b) as well as their properties were examined. The crystalline habits (a) are characterized by perfectly mirror‐like (100) surfaces and low dislocation densities. The type and concentration of charge carriers are mainly determined by the vapour composition within the crystallization zone and very from n = 3 × 1017 to p = 1 × 1019cm−3. These properties are the reason of the interest in shaped PbTe crystals for the aim of IR optoelectronic devices.
Chemical‐mechanical polishing of n—PbTe and n—Pb1‐xSnxTe crystals
Authors: Hitova L. , Trifonova E. P. 
Published: January 2007

AbstractPbTe and Pb1‐xSnxTe crystals are of very low hardness. Their mechanical treatment (cutting, lapping, polishing) results in the formation of a thick damaged surface layer (ENGEL et al.). The removing of the damaged layer by etch polishing affects the wafer planarity. The latter is of major importance when the wafers are used as substrates for epitaxial growth. The quality of the treated surfaces is significantly better when chemical‐mechanical polishing (CMP) is applied. For CMP of p‐PbTe and p‐Pb1‐xSnxTe BREITSAMETER et al. have proposed a solution containing potassium hexacyanoferrate (III), sodium hydroxide, glycerol or ethylenglycol. For CMP of Pb1‐xSnxTe STERNBERG and YELLIN have applied a solution of Br2 in HBr. This etchant, however, is strongly corrosive and requires the use of a special equipment.In the present work the conditions for CMP of n‐PbTe and n‐Pb1‐xSnxTe (x ∼ 0.2) with the etchant proposed by BREITSAMETER et al. have been investigated.
The morphology of witherite and strontianite grown in Silica Gel, by slow precipitation and on hydrothermal conditions
Authors: Franke W. , Hofer A. , Jelinski B. , Lenk K. 
Published: January 2007

AbstractBoth the gel method, slow precipitation, hydrogen carbonate transport at room temperature as well as hydrothermal transport in a carbon dioxide solution and the hydrothermal decomposition of the oxalates were used to grow BaCO3 and SrCO3. The morphology of the resulting crystals is described and compared with respect to theoretical considerations including the Donnay‐Harker rule and the PBC theory.
Basal twinning as a room temperature plastic deformation mode of chromium‐ and titanium‐doped sapphire crystals
Authors: Müller B. , Schulze D. 
Published: January 2007

AbstractThe degree of basal twinning caused by indentation was determined quantitatively on a series of chromium and titanium doped sapphire crystals with variours dopant contents. It depends on the dopant content significantly. The effect of titanium ions in reducing the degree of twinning is more pronounced than that of chromium dopants. This “size effect” of the dopant ions is consistent with the mechanism of basal twinning as reported by KRONBERG.
Neutron texture investigations of hard magnetic MnAl bars
Authors: Fuentes L. , Walther K. , Feldmann K. , Drechsler L. P. , Vlassova E. N. , Matorin V. I. , Betzl M. 
Published: January 2007

AbstractIn the present work connection between magnetic properties and texture of two samples of the tetragonal MnAl phase are investigated. For texture studies classical angle dispersive neutron diffraction and neutron time‐of‐flight method have been applied. the process of specimen preparation is shortly described. The mathematical treatment of experimental data for complete texture analysis has been outlined. The texture of investigated samples is weak. Some main components in inverse pole figures are inclined with respect to the direction of easy magnetization. In this way the non‐optimal magnetic properties of the investigated material can be explained.
Crystal and molecular structure of (21R)‐3β‐acetoxy‐14,21‐epoxy‐5β,14β‐card‐20(22)‐enolide
Authors: Pfeiffer D. , Reck G. , Lindig C. , Leibnitz P. 
Published: January 2007

AbstractThe title compound (21R)‐3β‐acetoxy‐14,21‐epoxy‐5β,14β‐card‐20(22)‐enolide crystallizes in the monoclinic space group P21 with 2 formular units C25H34O5 in the unit cell. The lattice parameters are a = 13.471, b = 7.959, c = 10.514 Å and β = 102.73°. The crystal structure was determined by direct methods and refined by least‐squares procedures to the discrepancy factor R = 0.045. Bond length, bond angles, ring conformations and the configuration at C(21) were determined. Intermolecular interactions are only of van der Waals type.
SIMS‐AES investigations of the oxygen adsorption on the (110) surface of Fe71Ni29
Authors: Uhlmann K. , Bardehle C. , Baunackw S. T. , Storbeck F. 
Published: January 2007

AbstractOxygen adsorption was investigated on the (110) surface of Fe71Ni29 at room temperature by means of the methods AES and SIMS. Three stages of interaction of oxygen with the surface could be determined. A dissociative chemisorption occurs in the dose range up to 5 L, surface oxides are nucleated between 5 L and about 40 L, and in the case of longer oxygen exposures a thicker oxide layer grows. At first, iron and nickel contribute to the surface reaction in like manner.
On the thermodynamic theory of dislocation etch‐pit formation
Authors: Koziejowska A. , Sangwal K. 
Published: January 2007

AbstractA logarithmic function of total dislocation energy, which includes Cabrera's and Schaarwächter's dislocation energy equations, is used to derive thermodynamic conditions for etch‐pit formation at dislocation sites. It is found that Cabrera's mechanism holds when the ratio of dislocation core radius rh to Frank's radius rF approaches zero. When 0 < rh/rF < 1, Cabrera‐type mechanism also holds, but the activation energy barrier is smaller than that in the original Cabrera's model and the undersaturation barrier Δμ* for spontaneous nucleation increases with an increase in rh/rF ratio. When rh/rF =1, the value of Δμ* is four‐times the value predicted by Cabrera's model. For rh/rF > 1, Schaarwächtertype mechanism involving no undersaturation barrier holds. A resume of Cabrera's and Schaarwächter's theories is also given.
Comparative characterization of boron‐implanted silicon after pulse laser annealing along single traces by SEM (SE, EBIC) and TEM studies
Authors: Johansen H. , Bartsch H. , Heydenreich J. , Lämmel B. 
Published: January 2007

Abstract(111) oriented n‐type silicon wafers which were implanted with 2 × 1015 B+/cm2 at 77 K and at an energy of 60 keV are laser annealed (Nd:YAG pulse laser) in air for mean laser powers between P = 1.8 W and P = 4.0 W. The comparative application of scanning electron microscopy (SE, EBIC) and high voltage transmission electron microscopy (HVTEM, 1000 keV) allows an estimation of the annealing quality in separated lines without overlapping. Values specifically ascertained by SEM in the SE contrast mode for the annealing threshold power Pth, the power range for optimal annealing ΔP0 and for the geometric width of the monocrystalline resolidification perpendicular to the direction of the specimen movement (and related to the spot diameter) at different laser pulse powers P agree completely with the results found in EBIC. At an optimal laser pulse power of P0 = 3.2 W HVTEM enables monocrystalline epitaxially resolidified areas free of defects to be identified in the same geometric width as that ascertained by SE and EBIC.
The transportation of brine inclusions in rock salt in a temperature field of a heat source
Authors: Müller E. 
Published: January 2007

AbstractThere are three kinds of brine inclusions in a natural crystal of halite, as follows: a) inclusion totally filled with brine; b) inclusions partially filled with brine and gas (SORBY inclusions) and c) inclusions totally filled with gas. Type a) and b) migrate in the crystal under the influence of a temperature gradient. Type c) inclusions do not move.This paper deals with the question whether the migration causes tracks in the crystal or not.In general, no tracks are caused directly by the motion of inclusions. However, there are some phenomena which can be explained as tracks. The reasons of these phenomena are examined and described.
Crystal and molecular structure of 3‐methoxy‐estra‐1,3,5(10)‐triene‐14β,17β‐diol, C19H26O3
Authors: Reck G. , Kretschmer R.‐G. , Schubert G. 
Published: January 2007

AbstractThe crystal and molecular structure of 3‐methoxy‐estra‐1,3,5(10)‐triene‐14β,17β‐diol has been determined by single crystal X‐ray analysis. It crystallizes in the orthorhombic space group P212121 with cell parameters a = 8.965(2), b = 30.520(7), and c = 6.031(2) A. The structure was solved by the POSIT system and refined by least‐squares calculations to the conventional R factor of 0.075. The steroid rings A, B, and C have planar, 7α, 8β‐half chair, and chair conformations, respectively. The ring D is intermediate between 13α, 14β‐half chair and 13α‐envelope. Rings B and C are trans‐fused, and rings C and D are cis‐fused. There are intra‐ as well as intermolecular hydrogen bonds between both hydroxyl groups of the steroid molecule.
Orientation of structure and crystals of TGS and TGS doped with D, al or L, al
Authors: Březina B. , Havránková M. 
Published: January 2007

AbstractA description of the various orientations of microstructure and large single crystals of triglycine sulphate (TGS) is reviewed. A difference of the orientation of TGS in polydomain state and in two possible singledomain states is discussed. The conclusions are applied to TGS crystals doped with L, alanine or D, alanine.
L‐alanine distribution in the growth pyramids of TGS crystals and its influence on the growth, switching and domain structure
Authors: Březina B. , Havránková M. 
Published: January 2007

AbstractThe full‐faced crystals of triglycine sulphate (TGS) and deuterated homologs substituted by L‐alanine (LATGS and LADTGS, resp.) were grown from growth solutions with various concentrations of the substituent. The distribution of L, alanine (L, al) in various growth pyramids of crystals was measured by the electrical switching method. The stability of domain structure of doped crystals was studied by the liquid crystal method.
Structure refinement with X‐ray powder diffraction data for synthetic calcium hydroxyapatite by Rietveld method
Authors: Pritzkow W. , Rentsch H. 
Published: January 2007

AbstractCa5(PO4)3OH, Mr = 502.3, hexagonal, P 63/m, a = 9.4207(3), c = 6.8780(2) Å, V = 528.67 Å3, Z = 2, Dx = 3.156 Mg · m−3, CuKα, λKα1 = 1.54051, λKα2 = 1.54433 Å, μ = 26.25 mm−1, F(000) = 500, T = 294 K. The powder diffraction pattern was analysed by the Rietveld method. The parameters were refined by the program PFSR (DBW2.9) to final R‐factors Rp = 0.079, Rwp = 0.081 and RB = 0.015.