CH3CN: X-ray structural investigation of a unique single crystal. β → α phase transition and crystal structure

2002 ◽  
Vol 58 (6) ◽  
pp. 1005-1010 ◽  
Author(s):  
Renée Enjalbert ◽  
Jean Galy
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
High Temperature ◽  
Transition Temperature ◽  
Single Crystal ◽  
Structural Investigation ◽  
X Ray ◽  
Α Phase ◽  
First Time

The phase transition from the low- (β) to the high-temperature (α) form of acetonitrile, CH3CN, has been directly observed and studied on a unique single crystal. Both the β and α structures have been determined at temperatures close to the transition temperature (206 K and 201 K), taking advantage of the hysteresis. A single crystal of the β form was obtained for the first time.

scholarly journals Raman Spectroscopy and Single-Crystal High-Temperature Investigations of Bentorite, Ca6Cr2(SO4)3(OH)12·26H2O

Minerals ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 38
Author(s):  
Rafał Juroszek ◽  
Biljana Krüger ◽  
Irina Galuskina ◽  
Hannes Krüger ◽  
Martina Tribus ◽  
...  
Keyword(s):  
Crystal Structure ◽  
High Temperature ◽  
Single Crystal ◽  
Chemical Formula ◽  
Crystal Chemical Formula ◽  
Single Crystal Diffraction ◽  
Bending Vibrations ◽  
X Ray ◽  
First Time

The crystal structure of bentorite, ideally Ca6Cr2(SO4)3(OH)12·26H2O, a Cr3+ analogue of ettringite, is for the first time investigated using X-ray single crystal diffraction. Bentorite crystals of suitable quality were found in the Arad Stone Quarry within the pyrometamorphic rock of the Hatrurim Complex (Mottled Zone). The preliminary semi-quantitative data on the bentorite composition obtained by SEM-EDS show that the average Cr/(Cr + Al) ratio of this sample is >0.8. Bentorite crystallizes in space group P31c, with a = b = 11.1927(5) Å, c =21.7121(10) Å, V = 2355.60(18) Å3, and Z = 2. The crystal structure is refined, including the hydrogen atom positions, to an agreement index R1 = 3.88%. The bentorite crystal chemical formula is Ca6(Cr1.613Al0.387)Σ2[(SO4)2.750(CO3)0.499]Σ3.249(OH)11.502·~25.75H2O. The Raman spectra of bentorite from two different localities exhibit the presence of the main stretching and bending vibrations related to the sulfate group at 983 cm−1 (ν1), 1109 cm−1 (ν3), 442 cm−1 (ν2), and 601 cm−1 (ν4). Moreover, the presence of bands assigned to the symmetric Cr(OH)63− stretching mode and hydroxyl deformation vibrations of Cr–OH units at ~540 cm−1 and ~757 cm−1, respectively, may be used to distinguish between ettringite and bentorite. In situ high temperature single crystal XRD experiments show that the decomposition of bentorite starts at ca. 45 °C and that a dehydroxylation product similar to metaettringite is formed.

O,O-diethyl O-[2-(dimethylamino)ethyl] phosphorothioate: structural evidence of the decomposition product and its oxalate salt

2019 ◽  
Vol 234 (9) ◽  
pp. 613-621
Author(s):  
Marc André Althoff ◽  
Jörn Frederik Martens ◽  
Marco Reichel ◽  
Manfred Metzulat ◽  
Thomas Matthias Klapötke ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Title Compound ◽  
Analytical Methods ◽  
Decomposition Product ◽  
X Ray Diffraction ◽  
X Ray ◽  
Rearrangement Process ◽  
Study Support ◽  
First Time

Abstract The molecular and single crystal structure of O,O-diethyl O-[2-(dimethylamino)ethyl] phosphorothioate oxalate, as determined by single crystal X-ray diffraction studies, is described for the first time; although this compound is well-known by industry and research from the mid-20th century. The known decomposition product of pure O,O-diethyl O-[2-(dimethylamino)ethyl] phosphorothioate could also be structurally characterized. Additionally, the compounds are characterized by recent analytical methods e.g. NMR. The findings of our study support the thesis that the isolated decomposition product must be a by-product of the thiono-thiolo rearrangement process of the title compound.

X-Ray and Raman Investigations on Cyanides ofMono- and DivalentMetals and Synthesis, Crystal Structure and Raman Spectrum of Tl5(CO3)2(CN)

2002 ◽  
Vol 57 (8) ◽  
pp. 895-900 ◽  
Author(s):  
Olaf Reckeweg ◽  
Arndt Simon
Keyword(s):  
Crystal Structure ◽  
Raman Spectroscopy ◽  
Raman Spectrum ◽  
Single Crystal ◽  
Aqueous Ammonia ◽  
Ammonia Solution ◽  
Aqueous Ammonia Solution ◽  
Divalent Metals ◽  
X Ray ◽  
First Time

Pseudobinary cyanides of monovalent and divalent metals were synthesized, and X-ray and Raman data of the cyanides were measured. Single crystal X-ray structure analyses were performed on Zn(CN)2 (Pn3̄m (No. 224), a = 591.32(7) pm), Hg(CN)2 (I4̄2d (No. 122), a = 969.22(14) and c = 890,15(18) pm) and for the first time on AgCN (I4̄2d (No. 166), a = 600.58(8) and c = 526.28(11) pm). The data are compared with literature data. The reaction of TlF and NaCN in 25% aqueous ammonia solution in air led to Tl5(CO3)2(CN) which was characterized by X-ray (Cmca (No. 64), 1468.1(3), 1171.6(2) and 1266.0(3) pm) and Raman spectroscopy.

High-temperature X-ray powder diffraction study of the tetragonal-cubic phase transition in nanocrystalline, compositionally homogeneous ZrO2–CeO2 solid solutions

2008 ◽  
Vol 23 (S1) ◽  
pp. S70-S74 ◽  
Author(s):  
L. M. Acuña ◽  
R. O. Fuentes ◽  
D. G. Lamas ◽  
I. O. Fábregas ◽  
N. E. Walsöe de Reca ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
High Temperature ◽  
Powder Diffraction ◽  
Solid Solutions ◽  
Tetragonal Phase ◽  
Room Temperature ◽  
Cubic Phase ◽  
X Ray ◽  
First Order

Crystal structure of compositionally homogeneous, nanocrystalline ZrO2–CeO2 solutions was investigated by X-ray powder diffraction as a function of temperature for compositions between 50 and 65 mol % CeO2. ZrO2-50 and 60 mol % CeO2 solid solutions, which exhibit the t′-form of the tetragonal phase at room temperature, transform into the cubic phase in two steps: t′-to-t″ followed by t″-to-cubic. But the ZrO2-65 mol % CeO2, which exhibits the t″-form, transforms directly to the cubic phase. The results suggest that t′-to-t″ transition is of first order, but t″-to-cubic seems to be of second order.

scholarly journals Ba2ZnGe2S6O: Ein neues Oxidsulfid mit Tetraedergerüststruktur/On Ba2ZnGe2S6O. A New Oxide Sulfide with Tetrahedral Framework Structure

1980 ◽  
Vol 35 (6) ◽  
pp. 672-675 ◽  
Author(s):  
Chr. L. Teske
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Coordination Sphere ◽  
Framework Structure ◽  
Tetrahedral Framework ◽  
Space Group ◽  
X Ray ◽  
Lattice Constants ◽  
First Time ◽  
Ray Methods

Abstract Ba2ZnGe2S6O was prepared for the first time and the crystal structure determined by using single crystal X-ray methods. The space group is D32d-P4̄21m, tetragonal (No. 113). Lattice constants: a = 963.59 ± 0.22; c = 645.06 ± 0.25 pm. The tetrahedral framework structure is described and discussed. Zn is linked only to sulfur. The oxygen belongs to the coordination sphere of Ge and Ba.

Structure of fluorite-like compound based on Nd5Mo3O16with lead partly substituting for neodymium

2015 ◽  
Vol 71 (2) ◽  
pp. 186-193 ◽  
Author(s):  
Alexander M. Antipin ◽  
Natalia I. Sorokina ◽  
Olga A. Alekseeva ◽  
Alexandra N. Kuskova ◽  
Elena P. Kharitonova ◽  
...  
Keyword(s):  
Crystal Structure ◽  
High Resolution ◽  
Single Crystal ◽  
Experimental Verification ◽  
X Ray Diffraction ◽  
Transmission Microscopy ◽  
X Ray ◽  
Oxygen Ion ◽  
First Time ◽  
Edx Microanalysis

A single crystal of Nd5Mo3O16with lead partly substituting for neodymium, which has a fluorite-like structure, was studied by precision X-ray diffraction, high-resolution transmission microscopy and EDX microanalysis. The crystal structure is determined in the space group Pn\bar 3n. It was found that the Pb atoms substitute in part for Nd atoms in the structure and are located in the vicinity of Nd2 positions. Partial substitutions of Mo cations for Nd positions and of Nd for Mo positions in crystals of theLn5Mo3O16oxide family are corroborated by X-ray diffraction for the first time. The first experimental verification of the location of an additional oxygen ion in the voids abutting MoO4tetrahedra was obtained.

scholarly journals Crystal Structure and Dielectric Property of Endohedral Lithium Fullerene

2014 ◽  
Vol 70 (a1) ◽  
pp. C195-C195
Author(s):  
Shinobu Aoyagi ◽  
Kunihisa Sugimoto ◽  
Hiroshi Okada ◽  
Norihisa Hoshino ◽  
Tomoyuki Akutagawa
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
Dielectric Property ◽  
Low Temperature ◽  
Dielectric Permittivity ◽  
Single Crystal ◽  
Temperature Dependence ◽  
Structure Analysis ◽  
X Ray ◽  
Dielectric Phase

Endohedral lithium fullerene Li+@C60 can have a dielectric polarization by the off-centered location of the Li+ cation inside the C60 cage. The x-ray structure analysis of the PF6– salt [Li@C60](PF6) revealed that the Li+ cation occupies two off-centered equivalent positions at 20 K and hence the crystal is non-polar [1]. The disordered structure at low temperature is explained by a static orientation disorder of polar Li+@C60 cations and/or a dynamic tunneling of the Li+ cation inside the C60 cage. The Li+ tunneling would be suppressed by an intermolecular interaction at lower temperature and a dielectric phase transition might be induced. We reveal the dielectric property and crystal structure of [Li@C60](PF6) below 20 K in this study. The temperature dependence of the dielectric permittivity was measured for the single crystal down to 9 K. The dielectric permittivity increases with decreasing temperature according to the Curie-Weiss law. Such a behavior was also observed in H2O@C60 crystal but not in empty C60 crystal [2]. No dielectric phase transition was observed in H2O@C60 down to 8 K. In contrast, a dielectric anomaly suggesting a phase transition was observed in [Li@C60](PF6) around 18 K. The single-crystal x-ray diffraction experiment below 20 K was also performed at SPring-8 BL02B1. The crystal has a cubic structure at 20 K [1]. The temperature dependence of the cubic lattice constant shows no anomaly around 18 K. However, diffraction peaks that are forbidden for the given structure appear below 18 K. Thus the crystal symmetry is lowered by the dielectric phase transition. We present the result of the crystal structure analysis of the newly discovered low-temperature phase.

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