Bestimmung der Röntgen-Debye-Temperatur aus dem Borrmann-Effekt in Germanium / Determination of the X-ray Debye Temperature in Germanium by Means of the Borrmann Effect

1973 ◽  
Vol 28 (7) ◽  
pp. 1204-1213 ◽  
Author(s):  
J. Ludewig
Keyword(s):  
Temperature Dependence ◽  
Compton Scattering ◽  
Debye Temperature ◽  
Low Temperatures ◽  
Room Temperature ◽  
Perfect Crystal ◽  
Photoelectric Absorption ◽  
Temperature Dependent ◽  
X Ray

The anomal transmission of CuK radiation through "thick"' perfect crystal slices of Germanium is strongly temperature dependent. This temperature dependence was measured between 293 and 6 K in the (220) symmetric Laue case and used to evaluate the Debye temperature θM . The wellknown uncorrected value θ′M = 290K was obtained near room temperature. Taking into account TDS and Compton scattering in addition to the photoelectric absorption the corrected value θM = 294 or 296 K was found, depending on the source of data. With decreasing temperature the corrected θM increases slightly up to a maximum at very low temperatures, as predicted by Batterman and Chipman and by Salter.

Homoleptische 1,4-Diazadienverbindungen elektronenarmer Übergangsmetalle. Synthese, Eigenschaften und Strukturen von (DAD)2Ti und (DAD)3Ti [1] / Homoleptic 1,4-Diazadiene Compounds of Early Transition Metals. Syntheses, Properties and Structures of (DAD)2Ti and (DAD)3Ti [1]

1994 ◽  
Vol 49 (4) ◽  
pp. 519-528 ◽  
Author(s):  
Richard Goddard ◽  
Carl Krüger ◽  
Ghassan Abdul Hadi ◽  
Karl-Heinz Thiele ◽  
Joachim Scholz
Keyword(s):  
Nmr Spectra ◽  
Room Temperature ◽  
Titanium Atom ◽  
Ring System ◽  
Temperature Dependent ◽  
X Ray ◽  
H Nmr ◽  
Tetrahedral Environment ◽  
Rigid Conformation

Syntheses and structures of homoleptic 1,4-diaza-1,3-diene (DAD) complexes of titanium are described. The spiranoid DAD complexes of formula (DAD)2Ti 3a-c are formed by reaction of TiCl4·2THF with the disodium salts Na2DAD 2a-c or by reduction of TiCl4·2TH F with magnesium in presence of two equivalents of DAD 1a-c . The endiaide complexes 3a-c are thermally stable, very sensitive to oxygen and water, and soluble in all com monorganic solvents. An X-ray crystal structure determination of 3 c reveals the titanium atom to be in a strongly distorted tetrahedral environment. The two five-membered metallacyclic rings are folded along the N,N′ axis. Temperature-dependent 1H NMR spectra of 3a-c indicate a rapid intramolecular inversion of this non-planar ring system in solution even at room temperature.Reduction of TiCl4·2THF with magnesium in presence of excess DAD 1d-f leads to the formation of the blue-violet complexes (DAD)3Ti 4d-f. At low temperatures three sterically crowded DAD ligands cause a rigid conformation as demonstrated by their unique lowtemperature 1H NMR spectra.

Single Crystal Growth of High-Pressure Phases of Ice and Salt Hydrate Far Below the Original Melting Point by Mixing Alcohol: Crystal Structure Determination of Magnesium Chloride Heptahydrate

2020 ◽  
Author(s):  
Keishiro Yamashita ◽  
Kazuki Komatsu ◽  
Hiroyuki Kagi
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
Crystal Growth ◽  
Single Crystal ◽  
Room Temperature ◽  
Growth Technique ◽  
Salt Hydrate ◽  
X Ray

An crystal-growth technique for single crystal x-ray structure analysis of high-pressure forms of hydrogen-bonded crystals is proposed. We used alcohol mixture (methanol: ethanol = 4:1 in volumetric ratio), which is a widely used pressure transmitting medium, inhibiting the nucleation and growth of unwanted crystals. In this paper, two kinds of single crystals which have not been obtained using a conventional experimental technique were obtained using this technique: ice VI at 1.99 GPa and MgCl<sub>2</sub>·7H<sub>2</sub>O at 2.50 GPa at room temperature. Here we first report the crystal structure of MgCl2·7H2O. This technique simultaneously meets the requirement of hydrostaticity for high-pressure experiments and has feasibility for further in-situ measurements.

Temperature-induced structural phase transitions in RERhSn (RE = Y, Gd-Tm, Lu)

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Simon Engelbert ◽  
Rolf-Dieter Hoffmann ◽  
Jutta Kösters ◽  
Steffen Klenner ◽  
Rainer Pöttgen
Keyword(s):  
Rare Earth ◽  
Phase Transitions ◽  
Driving Force ◽  
Room Temperature ◽  
Structural Phase ◽  
Structural Phase Transitions ◽  
Line Broadening ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
X Ray

Abstract The structures of the equiatomic stannides RERhSn with the smaller rare earth elements Y, Gd-Tm and Lu were reinvestigated on the basis of temperature-dependent single crystal X-ray diffraction data. GdRhSn crystallizes with the aristotype ZrNiAl at 293 and 90 K. For RE = Y, Tb, Ho and Er the HP-CeRuSn type (approximant with space group R3m) is already formed at room temperature, while DyRhSn adopts the HP-CeRuSn type below 280 K. TmRhSn and LuRhSn show incommensurate modulated variants with superspace groups P31m(1/3; 1/3; γ) 000 (No. 157.1.23.1) (γ = 3/8 for TmRhSn and γ = 2/5 for LuRhSn). The driving force for superstructure formation (modulation) is a strengthening of Rh–Sn bonding. The modulation is expressed in a 119Sn Mössbauer spectrum of DyRhSn at 78 K through line broadening.

X‐ray determination of the Debye temperature at high pressure using high‐energy synchrotron radiation

1990 ◽  
Vol 68 (6) ◽  
pp. 2719-2722 ◽  
Author(s):  
A. Matsumuro ◽  
M. Kobayashi ◽  
T. Kikegawa ◽  
M. Senoo
Keyword(s):  
High Pressure ◽  
Synchrotron Radiation ◽  
Debye Temperature ◽  
High Energy ◽  
X Ray

Structure determination of the 1/1 α/β mixed lactose by X-ray powder diffraction

2005 ◽  
Vol 61 (4) ◽  
pp. 455-463 ◽  
Author(s):  
Jacques Lefebvre ◽  
Jean-François Willart ◽  
Vincent Caron ◽  
Ronan Lefort ◽  
Frédéric Affouard ◽  
...  
Keyword(s):  
Powder Diffraction ◽  
Size Effects ◽  
Room Temperature ◽  
Real Space ◽  
Hydroxyl Groups ◽  
Soft Constraints ◽  
Rietveld Refinements ◽  
X Ray ◽  
Mixed Compound

The mixed form of α/β lactose was obtained by heating amorphous α-lactose at 443 K. NMR spectroscopy determined the stoichiometry of this mixed compound to be 1/1. The X-ray powder diffraction pattern was recorded at room temperature with a sensitive curved detector (CPS 120). The structure was solved by real-space methods (simulated annealing) followed by Rietveld refinements with soft constraints on bond lengths and bond angles. The H atoms of the hydroxyl groups were localized by minimization of the crystalline energy. The cell of 1/1 α/β lactose is triclinic with the space group P1 and contains two molecules (one molecule of each anomer). The crystalline cohesion is achieved by networks of O—H...O hydrogen bonds. The width of the Bragg peaks is interpreted through a microstructural approach in terms of isotropic strain effects and anisotropic size effects.

X-Ray Determination of the Debye Temperature of Uranium Monocarbide

1969 ◽  
Vol 36 (1) ◽  
pp. 135-142 ◽  
Author(s):  
R. Colella ◽  
D. Dragone ◽  
A. Merlini
Keyword(s):  
Debye Temperature ◽  
X Ray ◽  
Uranium Monocarbide

Complete determination of polarization state in the hard X-ray region

1991 ◽  
Vol 24 (6) ◽  
pp. 982-986 ◽  
Author(s):  
T. Ishikawa ◽  
K. Hirano ◽  
S. Kikuta
Keyword(s):  
Phase Shift ◽  
Linear Polarization ◽  
Amplitude Ratio ◽  
Polarization State ◽  
Perfect Crystal ◽  
Electric Vector ◽  
X Ray ◽  
Complete Determination ◽  
Unpolarized Radiation

A new method for complete determination of polarization state in the hard X-ray region is described. The system consists of a perfect-crystal phase retarder and a linear polarization analyzer. This method gives not only the amplitude ratio of mutually perpendicular electric vector components and the phase shift between them but also the proportion of unpolarized radiation.

Magnetic Properties of Sputtered Fe-O and Co-O Thin Films

1995 ◽  
Vol 403 ◽  
Author(s):  
D. V. Dimitrov ◽  
A. S. Murthy ◽  
G. C. Hadjipanayis ◽  
C. P. SWANN
Keyword(s):  
Grain Size ◽  
Low Temperatures ◽  
Room Temperature ◽  
Oxide Films ◽  
X Ray Diffraction ◽  
Dc Magnetron Sputtering ◽  
Large Shift ◽  
X Ray ◽  
Grain Size And Shape ◽  
Spherical Grains

AbstractFe-O and Co-O films were prepared by DC magnetron sputtering in a mixture of Ar and O2 gases. By varying the oxygen to argon ratio, oxide films with stoichiometry FeO, Fe3O4, α-Fe2O3, CoO and Co3O4 were produced. TEM studies showed that the Fe – oxide films were polycrystalline consisting of small almost spherical grains, about 10 nm in size. Co-O films had different microstructure with grain size and shape dependent on the amount of oxygen. X-ray diffraction studies showed that the grains in Fe-O films were randomly oriented in contrast to Co-O films in which a <111> texture was observed. Pure FeO and α-Fe2O3 films were found to be superparamagnetic at room temperature but strongly ferromagnetic at low temperatures in contrast to the antiferromagnetic nature of bulk samples. A very large shift in the hysteresis loop, about 3800 Oe, was observed in field cooled Co-CoO films indicating the presence of a large unidirectional exchange anisotropy.

Sign in / Sign up

Export Citation Format

Share Document