Space-Group Determination of the Orthorhombic Form of NaV6O11

1995 ◽  
Vol 28 (5) ◽  
pp. 599-603 ◽  
Author(s):  
Y. Kanke ◽  
H. Shigematsu ◽  
K. Ohshima ◽  
K. Kato
Keyword(s):  
Phase Transition ◽  
Low Temperature ◽  
Single Crystal ◽  
Diffraction Study ◽  
Structural Phase ◽  
Unit Cell ◽  
Single Crystal Diffraction ◽  
Space Group ◽  
X Ray

The unit cell and space group of orthorhombic NaV6O11 (low-temperature form) are found by an X-ray single-crystal diffraction study at 300 K (hexagonal, P63/mmc), 100 K (hexagonal, P63 mc) and 20 K (orthorhombic). The orthorhombic form (o) shows no superstructure and its unit cell is related to the hexagonal one (h): a o ≃ a h + b h , a o ≃ −a h + b h and c o ≃ c h . Bijvoet-pair examination confirms that it crystallizes in the noncentrosymmetric space group Cmc21. The hexagonal (P63 mc)-orthorhombic (Cmc21) structural phase transition is proved to be of second order.

A Low-Temperature X-Ray Diffraction Study of Structural Phase Transition in La1.86Sr0.14CuO4

1990 ◽  
Vol 29 (Part 1, No. 12) ◽  
pp. 2763-2767
Author(s):  
Yousuke Watanabe ◽  
Tetsuo Hanaguri ◽  
Tetsuo Fukase ◽  
Isao Tanaka ◽  
Hironao Kojima
Keyword(s):  
Phase Transition ◽  
Low Temperature ◽  
Diffraction Study ◽  
Structural Phase Transition ◽  
Structural Phase ◽  
X Ray Diffraction ◽  
X Ray

scholarly journals From space group to space groupoid: the partial symmetry of low-temperature E-vanillyl oxime

2019 ◽  
Vol 75 (4) ◽  
pp. 733-741
Author(s):  
Katharina Ehrmann ◽  
Stefan Baudis ◽  
Berthold Stöger
Keyword(s):  
Phase Transition ◽  
High Temperature ◽  
Low Temperature ◽  
Euclidean Space ◽  
Single Crystal ◽  
Connected Components ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
Full Symmetry

The phase transition of E-vanillyl oxime {1-[(E)-(hydroxyimino)methyl]-4-hydroxy-3-methoxybenzene, C8H9NO3} has been analysed by single-crystal and powder X-ray diffraction. The high-temperature (HT) phase (P21/a, Z′ = 1) transforms into the low-temperature (LT) phase (threefold superstructure, P\overline{1}, Z′ = 6) at ca 190 K. The point operations lost on cooling, {m [010], 2[010]}, are retained as twin operations and constitute the twin law. The screw rotations and glide reflections are retained in the LT phase as partial operations acting on a subset of Euclidean space {\bb E}^3. The full symmetry of the LT phase, including partial operations, is described by a disconnected space groupoid which is built of three connected components.

Single-Crystal X-Ray Diffraction Study of Na[OCN] at 170 K and its Vibrational Spectra

2010 ◽  
Vol 65 (4) ◽  
pp. 528-532 ◽  
Author(s):  
Olaf Reckeweg ◽  
Armin Schulz ◽  
Brian Leonard ◽  
Francis J. DiSalvo
Keyword(s):  
Single Crystal ◽  
Diffraction Study ◽  
Single Crystals ◽  
Vibrational Spectra ◽  
Unit Cell ◽  
Fermi Resonance ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
Rhombohedral Symmetry

The unit cell of Na[OCN] has been determined on single crystals at 170 K to have rhombohedral symmetry with the lattice parameters a = 356.79(10) and c = 1512.3(5) pm (hexagonal setting). According to the only model for which a converging refinement could be achieved, Na[OCN] crystallizes isopointal to β -NaN3 in the space group R¯3m (no. 166, Z = 3) with a statistically disordered [OCN]− anion. The positional coordinates and displacement parameters could not be separated for the O and N end atoms of the triatomic anion. The vibrational spectra show the frequencies typical for an [OCN]− moiety with Fermi resonance between the 2δ and the νsym vibrations for which the undisturbed frequencies were calculated.

scholarly journals Phase transition and proton ordering at 50 K in 3-(pyridin-4-yl)pentane-2,4-dione

2017 ◽  
Vol 73 (6) ◽  
pp. 1172-1178 ◽  
Author(s):  
Khai-Nghi Truong ◽  
Carina Merkens ◽  
Martin Meven ◽  
Björn Faßbänder ◽  
Richard Dronskowski ◽  
...  
Keyword(s):  
Phase Transition ◽  
Low Temperature ◽  
Single Crystal ◽  
Structural Phase ◽  
Pyridyl Ring ◽  
Temperature Phase ◽  
Crystallographic Axis ◽  
Temperature Phase Transition ◽  
Intramolecular Hydrogen ◽  
Low Temperature Phase

Single-crystal neutron diffraction experiments at 100 and 2.5 K have been performed to determine the structure of 3-(pyridin-4-yl)pentane-2,4-dione (HacacPy) with respect to its protonation pattern and to monitor a low-temperature phase transition. Solid HacacPy exists as the enol tautomer with a short intramolecular hydrogen bond. At 100 K, its donor···acceptor distance is 2.450 (8) Å and the compound adopts space group C2/c, with the N and para-C atoms of the pyridyl ring and the central C of the acetylacetone substituent on the twofold crystallographic axis. As a consequence of the axial symmetry, the bridging hydrogen is disordered over two symmetrically equivalent positions, and the carbon–oxygen bond distances adopt intermediate values between single and double bonds. Upon cooling, a structural phase transition to the t 2 subgroup P\bar 1 occurs; the resulting twins show an ordered acetylacetone moiety. The phase transition is fully reversible but associated with an appreciable hysteresis in the large single crystal under study: transition to the low-temperature phase requires several hours at 2.5 K and heating to 80 K is required to revert the transformation. No significant hysteresis is observed in a powder sample, in agreement with the second-order nature of the phase transition.

X-ray powder diffraction data for estra-4,9-diene-3,17-dione, C18H22O2

2020 ◽  
Vol 35 (4) ◽  
pp. 282-285
Author(s):  
Zhicheng Zha ◽  
Ting Tang ◽  
Xiaoyan Bian ◽  
Qing Wang
Keyword(s):  
Single Crystal ◽  
Cell Volume ◽  
Powder Diffraction ◽  
Structure Data ◽  
Diffraction Data ◽  
Unit Cell Volume ◽  
Unit Cell ◽  
Powder Diffraction Data ◽  
Space Group ◽  
X Ray

X-ray powder diffraction data for estra-4,9-diene-3,17-dione, C18H22O2, are reported [a = 9.236(7) Å, b = 10.294(4) Å, c = 15.471(1) Å, unit cell volume V = 1471.11 Å3, Z = 4, and space group P212121]. All measured lines were indexed and are consistent with the P212121 space group. No detectable impurities were observed. The single-crystallographic data of the compound are also reported [a = 9.2392(7) Å, b = 10.2793(5) Å, c = 15.4822(7) Å, unit cell volume V = 1470.37(15) Å3, Z = 4, and space group P212121]. Both single-crystal and powder diffraction methods can get the similar structure data.

Crystal Structure of the Dy3Ni11.83Si3.98 Compound

2019 ◽  
Vol 289 ◽  
pp. 77-81
Author(s):  
Bohdana Belan ◽  
Mykola Manyako ◽  
Katarzyna Pasinska ◽  
Marta Demchyna ◽  
Roman E. Gladyshevskii
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Large Family ◽  
Type Structure ◽  
Single Crystal Diffraction ◽  
Space Group ◽  
X Ray ◽  
Arc Melting ◽  
Pearson Symbol ◽  
Ternary Silicide

The new ternary silicide Dy3Ni11.83(1)Si3.98(1)was synthesized from the elements by arc-melting and its crystal structure was determined by X-ray single-crystal diffraction. The compound crystallizes in a Sc3Ni11Ge4-type structure: Pearson symbolhP38, space groupP63/mmc(No. 194),a= 8.1990(7),c= 8.6840(7) Å,Z= 2;R= 0.0222, wR= 0.0284 for 365 reflections. The structure belongs to a large family of structures related to the EuMg5.2type, with representatives among ternary aluminides, silicides, germanides,etc.

Sign in / Sign up

Export Citation Format

Share Document