scholarly journals Crystalline structures of Rb2UBr6 ionic conductor determined by neutron diffraction

Nukleonika ◽  
2020 ◽  
Vol 65 (1) ◽  
pp. 3-11
Author(s):  
Krzysztof Małetka ◽  
Eric Ressouche ◽  
Hakan Rundlof ◽  
Rolland Tellgren ◽  
Włodzimierz Szczepaniak ◽  
...  
Keyword(s):  
High Temperature ◽  
Neutron Diffraction ◽  
Neutron Powder Diffraction ◽  
Unit Cell ◽  
Structural Studies ◽  
Space Group ◽  
Lattice Constants ◽  
Temperature Range ◽  
Tetragonal Unit Cell ◽  
Trigonal Phase

AbstractThe neutron powder diffraction technique has been used for structural studies of Rb2UBr6 solid electrolyte as a function of temperature. The low-, room-, and high-temperature structures have been determined. At the temperature range of 4.2–80 K, the compound crystallizes in a monoclinic unit cell in the P21/c space group. At 80 K and 853 K, the compound crystallizes in a tetragonal unit cell in the P4/mnc space group. At 300 K, the lattice constants are a = b = 7.745(1) and c = 11.064(1) Å. At the temperature range of 853–960 K, a trigonal phase is observed in the Pʒ̄ml space group.

Synchrotron and neutron diffraction study of 4-methylpyridine-N-oxide at low temperature

2006 ◽  
Vol 62 (4) ◽  
pp. 627-633 ◽  
Author(s):  
Françoise Damay ◽  
Adrian Carretero-Genevrier ◽  
Alain Cousson ◽  
Wouter Van Beek ◽  
Juan Rodriguez-Carvajal ◽  
...  
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Structural Model ◽  
Neutron Diffraction Study ◽  
Unit Cell ◽  
Methyl Groups ◽  
Asymmetric Unit ◽  
Space Group ◽  
Face To Face ◽  
Tetragonal Unit Cell

The structure of 4-methylpyridine-N-oxide has been determined at 250, 100 and 10 K by combined synchrotron (C6H7NO) and neutron (C6D7NO) powder diffraction experiments. At 250 K the space group is I41/amd and the tetragonal unit cell [a = b = 7.941 (2), c = 19.600 (5) Å] contains eight equivalent molecules. At 100 K the structure is orthorhombic, with space group Fddd, a = 12.138 (2), b = 10.237 (2) and c = 19.568 (3) Å. The 16 equivalent molecules are rotated by about 8° around the c axis with respect to positions at high temperature. At 10 K the best structural model corresponds to a tetragonal unit cell with the space group P41, a = b = 15.410 (2) Å and c = 19.680 (3) Å. The 32 molecules (eight molecules in the asymmetric unit) show complex reorientations around the three cell axes. Whereas at 250 and 100 K the deuterated methyl groups are largely disordered, at 10 K they are ordered in-phase along infinite chains parallel to a and b. Face-to-face methyl groups along c are in an eclipsed configuration. The structure at 10 K suggests that the manifold of rotational tunnelling transitions could be due to inequivalent lattice sites for crystallographically independent methyl groups.

scholarly journals Lattice constants and thermal expansion of H2O and D2O Ice Ih between 10 and 265 K. Addendum

2012 ◽  
Vol 68 (1) ◽  
pp. 91-91 ◽  
Author(s):  
K. Röttger ◽  
A. Endriss ◽  
Jörg Ihringer ◽  
S. Doyle ◽  
W. F. Kuhs
Keyword(s):  
Thermal Expansion ◽  
Unit Cell ◽  
Acta Cryst ◽  
Lattice Constants ◽  
Temperature Range ◽  
Polynomial Fit ◽  
Polynomial Expression ◽  
Cell Data ◽  
Cell Volumes ◽  
Volume Cell

In a previous paper we reported the lattice constants and thermal expansion of normal and deuterated ice Ih [Röttger et al. (1994). Acta Cryst. B50, 644–648]. Synchrotron X-ray powder diffraction data were used to obtain the lattice constants and unit-cell volumes of H2O and D2O ice Ih in the temperature range 15–265 K. A polynomial expression was given for the unit-cell volumes. It turns out that the coefficients quoted have an insufficient number of digits to faithfully reproduce the volume cell data. Here we provide a table with more significant digits. Moreover, we also provide the coefficients of a polynomial fit to the previously published a and c lattice constants of normal and deuterated ice Ih for the same temperature range.

NQR and Crystal Structure of 4,5-Dichloroimidazole, C3H2N2Cl2

1992 ◽  
Vol 47 (1-2) ◽  
pp. 177-181 ◽  
Author(s):  
Shi-Qi Dou ◽  
Alarich Weiss
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
Temperature Dependence ◽  
Room Temperature ◽  
Unit Cell ◽  
Space Group ◽  
Temperature Range ◽  
Temperature Coefficients ◽  
Group D

AbstractThe two line 35Cl NQR spectrum of 4,5-dichloroimidazole was measured in the temperature range 77≦ T/K ≦ 389. The temperature dependence of the NQR frequencies conforms with the Bayer model and no phase transition is indicated in the curves v ( 35Cl)= f(T). Also the temperature coefficients of the 35Cl NQR frequencies are "normal". At 77 K the 35Cl NQR frequencies are 37.409 MHz and 36.172 MHz and at 389 K 35.758 MHz and 34.565 MHz. The compound crystallizes at room temperature with the tetragonal space group D44-P41212, Z = 8 molecules per unit cell; at 295 K : a = 684.2(5) pm, c = 2414.0(20) pm. The relations between the crystal structure and the NQR spectrum are discussed.

High-temperature diffraction experiments and phase diagram of ZrO2 and ZrSiO4

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Akira Yoshiasa ◽  
Tsubasa Tobase ◽  
Hiroshi Arima-Osonoi ◽  
Ken-Ichi Funakoshi ◽  
Osamu Ohtaka ◽  
...  
Keyword(s):  
High Temperature ◽  
Unit Cell ◽  
Cubic Phase ◽  
Imaging Plate ◽  
X Ray Diffraction ◽  
Space Group ◽  
Cell Parameters ◽  
Time Observation ◽  
Short Time ◽  
Clear Change

Abstract High-temperature X-ray diffraction (XRD) experiments up to T = 2710 °C have been performed on ZrSiO4 and ZrO2 powders, using the container-less levitation technique. A two-dimensional imaging plate (IP) detector was used for short-time observation. The diffraction data in a wide area was projected in one dimension. The unit cell parameters, thermal expansions, and c/a ratios for ZrSiO4 (space group I41/amd and Z = 4), tetragonal ZrO2 (space group P42/nmc and Z = 2) and cubic ZrO2 (space group  F m 3   ‾ m $Fm3‾{}m$ and Z = 4) were measured to understand the high-temperature behaviors. The transition temperature between tetragonal and cubic ZrO2 was specified to be between 2430 and 2540 °C. The pre-transitional behavior was observed around 2200 °C. As no clear change in unit cell volume is evident, the phase boundary between the tetragonal and the cubic phase has been shown to be a positive slope. The ZrO2 and ZrO2–SiO2 phase diagrams are proposed based on the chemical composition and the crystal structure.

scholarly journals Synthesis, Crystal Structure and Magnetic Behaviour of Dimeric and Polymeric Gadolinium Trifluoroacetate Complexes

2006 ◽  
Vol 61 (6) ◽  
pp. 699-707 ◽  
Author(s):  
Daniela John ◽  
Alexander Rohde ◽  
Werner Urland
Keyword(s):  
Crystal Structure ◽  
Magnetic Behaviour ◽  
Magnetic Data ◽  
Space Group ◽  
X Ray ◽  
Lattice Constants ◽  
Temperature Range ◽  
X Ray Crystallography ◽  
Carboxylate Groups

The gadolinium(III) trifluoroacetates ((CH3)2NH2)[Gd(CF3COO)4] (1), ((CH3)3NH)[Gd(CF3 COO)4(H2O)] (2), Gd(CF3COO)3(H2O)3 (3) as well as Gd2(CF3COO)6(H2O)2(phen)3 · C2H5OH (4) (phen = 1,10-phenanthroline) were synthesized and structurally characterized by X-ray crystallography. These compounds crystallize in the space group P1̅ (No. 2, Z = 2) (1, 2 and 4) and P 21/c (No. 14, Z = 4) (3), respectively, with the following lattice constants 1: a = 884.9(2), b = 1024.9(2), c = 1173.1(2) pm, α = 105.77(2), β = 99.51(2), γ = 107.93(2)°; 2: a = 965.1(1), b = 1028.6(1), c = 1271.3(2) pm, α = 111.83(2), β = 111.33(2), γ = 90.44(2)°; 3: a = 919.6(2), b = 1890.6(4), c = 978.7(2) pm, β = 113.94(2)°; 4: a = 1286.7(8), b = 1639.3(8), c = 1712.2(9) pm, α = 62.57(6), β = 84.13(5), γ = 68.28(5)°. The compounds consist of Gd3+ ions which are bridged by carboxylate groups either to chains (1 and 2) or to dimers (3 and 4). In addition to the Gd3+ dimers, compound (4) also contains monomeric Gd3+ units. The magnetic behaviour of 2 and 3 was investigated in a temperature range of 1.77 to 300 K. The magnetic data for these compounds indicate weak antiferromagnetic interactions

Anionische Komplexe [Mo2(O2CPh)4X2]2⊖ mit X = N3, Cl, Br. Die Kristallstruktur von (PPh4)2[Mo2(O2CPh)4Cl2] · 2CH2Cl2 / Anionic Complexes [Mo2(O2C-Ph)4X2]2⊖ with X = N3, Cl, Br. The Crystal Structure of (PPh4)2[Mo2(O2C-Ph)4Cl2] · 2CH2Cl2

1985 ◽  
Vol 40 (1) ◽  
pp. 13-18 ◽  
Author(s):  
Kay Jansen ◽  
Kurt Dehnicke ◽  
Dieter Fenske
Keyword(s):  
Crystal Structure ◽  
Ir Spectra ◽  
Diffraction Data ◽  
Unit Cell ◽  
Monoclinic Space Group ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
Lattice Constants ◽  
Anionic Complexes

The syntheses and IR spectra of the complexes [Mo2(O2C-Ph)4X2]2⊖ with X = N3, CI, Br and the counter ion PPh4⊕ are reported. The azido and the bromo complexes are obtained from a solution of [Mo2(O2CPh)4] with PPh4N3 in pyridine or by reaction with PPh4Br in CH2Br2, respectively. When (PPh4)2[Mo2(O2CPh)4(N3)2] is dissolved in CH2Cl2, nitrogen is evolved and the complex with X = CI is obtained. The crystal structure of (PPh4)2[Mo2(O2CPh)4Cl2] · 2CH2Cl2 was determined from X-ray diffraction data (5676 observed independent reflexions, R = 0.042). It crystallizes in the monoclinic space group P21/n with four formula units per unit cell; the lattice constants are a = 1549, b = 1400, c = 1648 pm, β = 94.6°. The centrosymmetric [Mo2(O2CPh)4Cl2]2⊖ ion has a rather short Mo-Mo bond of 213 pm, whereas the MoCl bonds are very long (288 pm)

scholarly journals Crystal Chemistry and High-Temperature Behaviour of Ammonium Phases NH4MgCl3·6H2O and (NH4)2Fe3+Cl5·H2O from the Burned Dumps of the Chelyabinsk Coal Basin

Minerals ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 486 ◽  
Author(s):  
Andrey A. Zolotarev ◽  
Elena S. Zhitova ◽  
Maria G. Krzhizhanovskaya ◽  
Mikhail A. Rassomakhin ◽  
Vladimir V. Shilovskikh ◽  
...  
Keyword(s):  
Crystal Structure ◽  
High Temperature ◽  
Unit Cell ◽  
X Ray Diffraction ◽  
Coal Basin ◽  
Unit Cell Parameters ◽  
Space Group ◽  
X Ray ◽  
Cell Parameters ◽  
Mineral Phases

The technogenic mineral phases NH4MgCl3·6H2O and (NH4)2Fe3+Cl5·H2O from the burned dumps of the Chelyabinsk coal basin have been investigated by single-crystal X-ray diffraction, scanning electron microscopy and high-temperature powder X-ray diffraction. The NH4MgCl3·6H2O phase is monoclinic, space group C2/c, unit cell parameters a = 9.3091(9), b = 9.5353(7), c = 13.2941(12) Å, β = 90.089(8)° and V = 1180.05(18) Å3. The crystal structure of NH4MgCl3·6H2O was refined to R1 = 0.078 (wR2 = 0.185) on the basis of 1678 unique reflections. The (NH4)2Fe3+Cl5·H2O phase is orthorhombic, space group Pnma, unit cell parameters a = 13.725(2), b = 9.9365(16), c = 7.0370(11) Å and V = 959.7(3) Å3. The crystal structure of (NH4)2Fe3+Cl5·H2O was refined to R1 = 0.023 (wR2 = 0.066) on the basis of 2256 unique reflections. NH4MgCl3·6H2O is stable up to 90 °C and then transforms to the less hydrated phase isotypic to β-Rb(MnCl3)(H2O)2 (i.e., NH4MgCl3·2H2O), the latter phase being stable up to 150 °C. (NH4)2Fe3+Cl5·H2O is stable up to 120 °C and then transforms to an X-ray amorphous phase. Hydrogen bonds provide an important linkage between the main structural units and play the key role in determining structural stability and physical properties of the studied phases. The mineral phases NH4MgCl3·6H2O and (NH4)2Fe3+Cl5·H2O are isostructural with natural minerals novograblenovite and kremersite, respectively.

Measurement of Atomic Elastic Constants by Pulsed Neutron Powder Diffraction

1992 ◽  
Vol 36 ◽  
pp. 577-583
Author(s):  
A. C. Lawson ◽  
G. H. Kwei ◽  
J. A. Goldstone ◽  
B. Cort ◽  
R. I. Sheldon ◽  
...  
Keyword(s):  
High Temperature ◽  
Neutron Diffraction ◽  
Rietveld Refinement ◽  
Powder Diffraction ◽  
Elastic Constants ◽  
Diffraction Data ◽  
High Temperature Superconductors ◽  
Neutron Powder Diffraction ◽  
Neutron Diffraction Data ◽  
Pulsed Neutron

AbstractWe have developed a technique for determining the atomic elastic constants from measurements of the Debye-Waller factors. The Debye-Waller factors are obtained by Rietveld refinement of time-of-flight neutron diffraction data and interpreted in terms of an atomic Debye-Waller temperature. The method is applicable to powders and to materials that must be encapsulated for safety or environmental reasons. We will illustrate our technique with applications to actinide metals, to metallic hydrides and to high-temperature superconductors.

Quaternäre Strontium-Kupfer(I)-Lanthanoid(III)-Selenide mit Cer und Praseodym: SrCuCeSe3 und SrCuPrSe3, ein ungleiches Geschwisterpaar / Quaternary Strontium Copper(I) Lanthanoid(III) Selenides with Cerium and Praseodymium: SrCuCeSe3 and SrCuPrSe3, Unequal Brother and Sister

2004 ◽  
Vol 59 (9) ◽  
pp. 985-991 ◽  
Author(s):  
Sabine Strobel ◽  
Thomas Schleid
Keyword(s):  
Single Crystals ◽  
Coordination Number ◽  
Unit Cell ◽  
Structural Relationship ◽  
The Other ◽  
Space Group ◽  
Lattice Constants ◽  
The Third ◽  
Other Hand ◽  
Third Dimension

Quaternary strontium copper(I) lanthanoid(III) selenides are formed by the oxidation of elemental strontium, copper and the corresponding lanthanoid with selenium. Orange to red needle-shaped single crystals of SrCuPrSe3 and SrCuCeSe3 have been synthesized by heating mixtures of Sr, Cu, Pr / Ce and Se with CsI as a flux in evacuated silica tubes to 800°C for 7 d. Both compounds crystallize orthorhombically in space group Pnma with four formula units per unit cell, but with unlike lattice constants (a = 1097.32(6), b = 416.51(2), c = 1349.64(8) pm for SrCuPrSe3 and a = 846.13(5), b = 421.69(2), c = 1663.42(9) pm for SrCuCeSe3) and therefore different structure types. The Pr3+ cations in SrCuPrSe3 are surrounded octahedrally by six Se2− anions forming chains of edge-sharing [PrSe6]9− octahedra that are joined by common vertices. Together with [CuSe4]7− tetrahedra they form [CuPrSe3]2− layers piled up parallel (001). Between those layers the Sr2+ cations are coordinated by seven Se2− anions in the shape of capped trigonal prisms linking the structure in the third dimension. On the other hand in SrCuCeSe3 the Ce3+ cations as well as the Sr2+ cations adopt a coordination number of seven. Since the bonding distances between cerium and selenium match with those of strontium and selenium the two crystallographically independent sites of these cations are occupied statistically by Ce3+ and Sr2+ with equal ratios. Nevertheless, there is a close structural relationship between SrCuPrSe3 and SrCuCeSe3. Similar to SrCuPrSe3 where Cu+ and Pr3+ cations together with Se2− anions form [CuPrSe3]2− layers parallel (001), the Cu+ cations and [(Ce1/Sr1)Se7]11.5− polyhedra in SrCuCeSe3 build strongly puckered layers which are connected by (Ce2)3+/(Sr2)2+ cations. The copper selenium part in both compounds correlates as well, with [CuSe4]7− tetrahedra linked by common vertices to form [CuSe3]5− chains running along [010].

Notizen: Eine neue bicyclische Zinn-Selen-Verbindung. Synthese und Kristallstruktur von [{Cp(CO)2Fe}3ClSn3Se4] / A New Bicyclic Tin Selenium Compound. Synthesis and Crystal Structure of [{Cp(CO)2Fe}3ClSn3Se4]

1993 ◽  
Vol 48 (7) ◽  
pp. 1009-1012 ◽  
Author(s):  
Kurt Merzweiler ◽  
Harald Kraus
Keyword(s):  
Crystal Structure ◽  
Structure Determination ◽  
Unit Cell ◽  
Monoclinic Space Group ◽  
Synthesis And Crystal Structure ◽  
Selenium Compound ◽  
Space Group ◽  
X Ray ◽  
Lattice Constants ◽  
Compound Synthesis

[{Cp(CO)2Fe}SnCl3] reacts with Na2Se in THF to form the compound [{Cp(CO)2Fe}3ClSn3Se4] 1. 1 crystallizes in the monoclinic space group P21/n with 4 formula units per unit cell. The lattice constants are α = 1435.2(7), b = 1124.4(4), c = 1972.7(12) pm, β = 94.59(4)°. According to the X-ray structure determination 1 contains a bicyclic Sn3Se4 framework.

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