Low-temperature Crystal Structure and 57Fe Mössbauer Spectroscopy of Sr3Sc2O5Fe2As2

2009 ◽  
Vol 64 (7) ◽  
pp. 815-820 ◽  
Author(s):  
Marcus Tegela ◽  
Inga Schellenberg ◽  
Franziska Hummel ◽  
Rainer Pöttgen ◽  
Dirk Jorendt
Keyword(s):  
Crystal Structure ◽  
Low Temperature ◽  
Isomer Shift ◽  
Quadrupole Splitting ◽  
Spectroscopic Data ◽  
Bond Angle ◽  
Magnetic Ordering ◽  
Structural Instability ◽  
Low Temperature Crystal Structure ◽  
Tetragonal Cell

The crystal structure of the layered iron arsenide Sr3Sc2O5Fe2As2 was determined between 300 and 10 K. The lattice parameters of the tetragonal cell decrease anisotropically according to Δc/c : Δa/a ≈ 4.2, which results in a slight flattening of the As-Fe-As bond angle within the FeAs layers. No indication of a structural instability could be detected. 57Fe Mössbauer spectroscopic data show only a single signal at 4.2, 77, and 298 K, subjected to quadrupole splitting. The isomer shift increases from 0.36(1) mms−1 at 298 K to 0.49(1) mms−1 at 4.2 K. No indication for magnetic ordering was found.

scholarly journals Low-Temperature Crystal Structure and Mean-Field Modeling of ErxDy1−xAl2 Intermetallics

Metals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1662
Author(s):  
Yaroslav Mudryk ◽  
Bruno P. Alho ◽  
Paula O. Ribeiro ◽  
Vitalij K. Pecharsky
Keyword(s):  
Crystal Structure ◽  
Low Temperature ◽  
Mean Field Theory ◽  
Mean Field ◽  
Magnetic Ordering ◽  
X Ray Diffraction ◽  
Easy Magnetization ◽  
Rhombohedral Distortion ◽  
Magnetization Axis ◽  
Low Temperature Crystal Structure

Low-temperature crystal structure of the ErxDy1−xAl2 alloys with x = 0.45, 0.67, 0.90 was examined using temperature-dependent powder X-ray diffraction. The Er-rich sample, Er0.9Dy0.1Al2, exhibits a rhombohedral distortion associated with the magnetic ordering that occurs around 20 K. The rhombohedral distortion is suppressed in Er0.67Dy0.33Al2, while a weak low-temperature tetragonal distortion is observed in Er0.45Dy0.55Al2. The mean-field theory supports the correlation between the type of structural distortion and the variable easy magnetization axis in ErxDy1−xAl2 intermetallics.

Thermally Induced Symmetry and Disorder: The Low-Temperature Crystal Structure of Diaquadichlorodimethyltin · 15-crown-5

1996 ◽  
Vol 1 (3) ◽  
pp. 359-363 ◽  
Author(s):  
Glenn P. A. Yap ◽  
Mostafa M. Amini ◽  
Seik W. Ng ◽  
Anne E. Counterman ◽  
Arnold L. Rheingold
Keyword(s):  
Crystal Structure ◽  
Low Temperature ◽  
Thermally Induced ◽  
Low Temperature Crystal Structure

Low-temperature crystal structure of RS-thiocamphor

2004 ◽  
Vol 219 (9) ◽  
Author(s):  
E. Louise R. Robins ◽  
Michela Brunelli ◽  
Asiloé J. Mora ◽  
Andrew N. Fitch
Keyword(s):  
Crystal Structure ◽  
Phase Transitions ◽  
Low Temperature ◽  
Room Temperature ◽  
Cubic Phase ◽  
X Ray Diffraction ◽  
Orthorhombic Space Group ◽  
Two Phase ◽  
X Ray ◽  
Low Temperature Crystal Structure

AbstractDSC and high-resolution powder X-ray diffraction measurements in the range 295 K–100 K show that RS-thiocamphor undergoes two phase transitions. The first, at around 260 K on cooling, is from the room-temperature body-centred-cubic phase to a short-lived intermediate. At 258 K the low-temperature form starts to appear. The crystal structure of the latter is orthorhombic, space group

Low temperature crystal structure and large lattice discontinuity at Tcin superconducting FeTeOxfilms

2013 ◽  
Vol 103 (10) ◽  
pp. 102604 ◽  
Author(s):  
L. K. Narangammana ◽  
X. Liu ◽  
Y. F. Nie ◽  
F. J. Rueckert ◽  
J. I. Budnick ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Low Temperature ◽  
Low Temperature Crystal Structure ◽  
Large Lattice

The low-temperature crystal structure of magnetite

1953 ◽  
Vol 6 (6) ◽  
pp. 565-566 ◽  
Author(s):  
H. P. Rooksby ◽  
B. T. M. Willis
Keyword(s):  
Crystal Structure ◽  
Low Temperature ◽  
Low Temperature Crystal Structure

scholarly journals Low-temperature crystal structure of 4-chloro-1H-pyrazole

2021 ◽  
Vol 77 (9) ◽  
pp. 955-957
Author(s):  
Kelly Rue ◽  
Raphael G. Raptis
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Carbon Atom ◽  
Low Temperature ◽  
Chlorine Atom ◽  
Molecular Assembly ◽  
Mirror Plane ◽  
X Rays ◽  
Asymmetric Unit ◽  
Low Temperature Crystal Structure

The structure of 4-chloro-1H-pyrazole, C3H3ClN2, at 170 K has orthorhombic (Pnma) symmetry and is isostructural to its bromo analogue. Data were collected at low temperature since 4-chloro-1H-pyrazole sublimes when subjected to the localized heat produced by X-rays. The structure displays intermolecular N—H...N hydrogen bonding and the packing features a trimeric molecular assembly bisected by a mirror plane (m normal to b) running through one chlorine atom, one carbon atom and one N—N bond. The asymmetric unit therefore consists of one and one-half 4-chloro-1H-pyrazole molecules. Thus, the N—H proton is crystallographically disordered over two positions of 50% occupancy each.

scholarly journals TheZ′ = 12 superstructure of Λ-cobalt(III) sepulchrate trinitrate governed by C—H...O hydrogen bonds

2016 ◽  
Vol 72 (3) ◽  
pp. 372-380 ◽  
Author(s):  
Somnath Dey ◽  
Andreas Schönleber ◽  
Swastik Mondal ◽  
Siriyara Jagannatha Prathapa ◽  
Sander van Smaalen ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Low Temperature ◽  
Hydrogen Bonds ◽  
Room Temperature ◽  
Structural Parameters ◽  
Molecular Packing ◽  
Nitrate Group ◽  
Structural Variations ◽  
Monoclinic Symmetry ◽  
Low Temperature Crystal Structure

Λ-Cobalt(III) sepulchrate trinitrate crystallizes inP6322 withZ= 2 (Z′ = 1/6) at room temperature. Slabs perpendicular to the hexagonal axis comprise molecules Co(sepulchrate) alternating with nitrate groupsAandB. Coordinated by six sepulchrate molecules, highly disordered nitrate groupsCare accommodated between the slabs. Here we report the fully ordered, low-temperature crystal structure of Co(sep)(NO3)3. It is found to be a high-Z′ structure withZ′ = 12 of the 12-fold 6a_{h}\times\sqrt{3}b_{h}\times c_{h} superstructure with monoclinic symmetryP21(cunique). Correlations between structural parameters are effectively removed by refinements within the superspace approach. Superstructure formation is governed by a densification of the packing in conjunction with ordering of nitrate groupC, the latter assuming different orientations for each of theZ′ = 12 independent copies in the superstructure. The Co(sep) moiety exhibits small structural variations over its 12 independent copies, while orientations of nitrate groupsAandBvary less than the orientations of the nitrate groupCdo. Molecular packing in the superstructure is found to be determined by short C—H...H—C contacts, with H...H distances of 2.2–2.3 Å, and by short C—H...O contacts, with H...O distances down to 2.2 Å. These contacts presumably represent weak C—H...O hydrogen bonds, but in any case they prevent further densification of the structure and strengthening of weak N—H...O hydrogen bonds with observed H...O distances of 2.4–2.6 Å.

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