The low-temperature behaviour of cancrinite:an in situ single-crystal X-ray diffraction study

2012 ◽  
Vol 76 (4) ◽  
pp. 933-948 ◽  
Author(s):  
G. Diego Gatta ◽  
P. Lotti ◽  
V. Kahlenberg ◽  
U. Haefeker
Keyword(s):  
Low Temperature ◽  
Single Crystal ◽  
Structure Refinement ◽  
Ambient Conditions ◽  
X Ray Diffraction ◽  
Structural Behaviour ◽  
X Ray ◽  
Positional Disorder ◽  
Deformation Processes

AbstractThe low-temperature structural behaviour of natural cancrinite with a formula Na6.59Ca0.93[Si6.12Al5.88O24](CO3)1.04F0.41·2H2O has been investigated by means of in situ single-crystal X-ray diffraction and Raman spectroscopy. High quality structure refinements were obtained at 293, 250, 220, 180, 140, 100 and at 293 K again (at the end of the low-T experiments). The variation in the unit-cell volume as a function of temperature (T) exhibits a continuous trend, without any evident thermoelastic anomaly. The thermal expansion coefficient αV = (1/V)∂V/∂T is 3.8(7) × 10–5 K–1 (between 100 and 293 K). The structure refinement based on intensity data collected at ambient conditions after the low-T experiment confirmed that the low-T induced deformation processes are completely reversible. The extraframework population does not show significant variations down to 100 K. The strong positional disorder of the carbonate groups along the c axis persists within the T range investigated. The structural behaviour of cancrinite at low-T is mainly governed by the continuous framework rearrangement through the ditrigonalization of the six-membered rings which lie in a plane perpendicular to [0001], the contraction of the four-membered ring joint units, the decrease of the ring corrugation in the (0001) plane, and the flattening of the cancrinite cages. A list of the principal Raman active modes in ambient conditions is provided and discussed.

In situ high temperature single crystal X-ray diffraction study of a natural omphacite

2000 ◽  
Vol 64 (6) ◽  
pp. 983-993 ◽  
Author(s):  
A. Pavese ◽  
R. Bocchio ◽  
G. Ivaldi
Keyword(s):  
High Temperature ◽  
Single Crystal ◽  
Diffusion Processes ◽  
Ambient Conditions ◽  
X Ray Diffraction ◽  
Structural Behaviour ◽  
X Ray ◽  
Thermal Expansion Coefficients ◽  
Using Data

AbstractIn situ high temperature single crystal X-ray diffraction (XRD) experiments have been performed on a chemically quasi-ideal omphacite sample up to 1000°C. The lattice parameters were studied as a function of temperature, and their thermal expansion coefficients determined. The b and c cell edges show discontinuities as a function of temperature which are interpreted here in terms of intracrystalline cation diffusion processes. Structure refinements have been carried out using data collected at room temperature, at 800°C and at ambient conditions after cooling. The structural behaviour as a function of temperature of chemically quasi-ideal omphacites is compared with those of jadeite and diopside.

Structural intergrowth of merlinoite/phillipsite and its temperature-dependent dehydration behaviour: a single-crystal X-ray study

2015 ◽  
Vol 79 (1) ◽  
pp. 191-203 ◽  
Author(s):  
Rosa Micaela Danisi ◽  
Thomas Armbruster ◽  
Mariko Nagashima
Keyword(s):  
Single Crystal ◽  
Unit Cell Volume ◽  
Structure Refinement ◽  
Ambient Conditions ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
X Ray ◽  
Khibiny Massif ◽  
Low Symmetry

AbstractSupposed 'merlinoite' crystals from Monte Somma, Vesuvius (Italy) and Fosso Attici, north of Rome (Italy) represent highly twinned coherent intergrowths between merlinoite and phillipsite on a submicroscopic level. The MER (Immm, a ≈ 14.1, b ≈ 14.2, c ≈ 9.9 Å) and PHI (P 21/m, a ≈ 9.9, b ≈ 14.3, c ≈ 8.7 Å, β = 124.8°) frameworks of similar composition are assembled from identical tetrahedral units, though with a different connectivity. Coherent intergrowth and twinning of the two frameworks lead to P42/mnm pseudosymmetry, which is diagnostic of the intergrowth. Under ambient conditions merlinoite has Immm symmetry or I4/mmm if twinned. a low-symmetry model of space group P121/m1 (a ≈ 14.2, b ≈ 14.2, c ≈ 10 Å, β = 90°) allows structure refinement and quantification of the two frameworks.Upon in situ dehydration to 250°C the evolution of the unit-cell volume of the Monte Somma merlinoite/phillipsite intergrowth displays an intermediate trend between previously studied pure merlinoite from the Khibiny massif (Russia) and Ba-rich phillipsite.The Monte Somma crystal studied by temperature-dependent single-crystal X-ray diffraction methods also contained a subordinate chabazite inclusion with no coherent structural relationship to the merlinoite/phillipsite framework. Thus, the modification of the chabazite framework on dehydration could also be studied.

scholarly journals Crystal structure refinement of MgSiO3high temperature C2/c clinoenstatite

2014 ◽  
Vol 70 (a1) ◽  
pp. C79-C79
Author(s):  
Akira Yoshiasa ◽  
Akihiko Nakatsuka ◽  
Maki Okube ◽  
Tomoo Katsura
Keyword(s):  
High Temperature ◽  
Single Crystal ◽  
Structure Refinement ◽  
Ambient Conditions ◽  
X Ray Diffraction ◽  
Temperature Quenching ◽  
Single Crystal Diffraction ◽  
X Ray ◽  
Metastable Structure ◽  
Rapid Pressure

The high-temperature clinoenstatite (HT-CEn) is one of the important MgSiO3 pyroxene polymorph. The single-crystal of C2/c HT-CEn endmember is firstly synthesized by rapid pressure-temperature quenching from 15-16 GPa and 900-19000C [1]. No report that it is produced as single crystal or large domain has been made on the MgSiO3 endmember. The HT-CEn-type modifications are observed in Ca-poor Mg-Fe clinoenstatite and pigeonite and are always found to be unquenchable in rapid cooling. The high pressure and high temperature experiments of MgSiO3 composition were carried out with a Kawai-type multi-anvil apparatus. The samples were quenched by rapidly releasing the oil pressure load and/or by blow out of anvil cell gasket. The space group of C2/c is strictly determined by Rigaku RAPID Weissenberg photographs and synchrotron radiation. Single-crystal X-ray diffraction experiments were performed at ambient conditions using a Rigaku AFC-5 four circle diffractometer. A total of 9383 reflections was measured and averaged in Laue symmetry 2/m to give 766 independent reflections used for the structure refinements. Final reliability factors converged smoothly to R = 0.029. The single-crystal diffraction analysis shows that the unusual bonding distances frozen in this metastable structure. The degree of kinking of the silicate tetrahedral chains is 1750for HT-CEn. The chain angle for HP-CEn is substantially smaller (1350) and the angle for L-CEn turned to the opposite direction at -1600(=2000). The degree of kinking increases by being curved in more than 1800in the transition from HT-CEn to L-CEn. As for the reverse change from the expansion to the stretch, a potential barrier exists in the point of the continuity. It is suggested that the reason which can quench structure under ambient conditions is the present HT-CEn single crystal was formed by the isosymmetric phase transition from HP-CEn. HT-CEn type single-crystals cannot be frozen without pressure.

Armstrongite at non-ambient conditions: An in-situ high-pressure single-crystal X-ray diffraction study

2019 ◽  
Vol 274 ◽  
pp. 171-175 ◽  
Author(s):  
Davide Comboni ◽  
Paolo Lotti ◽  
G. Diego Gatta ◽  
Maria Lacalamita ◽  
Ernesto Mesto ◽  
...  
Keyword(s):  
High Pressure ◽  
Single Crystal ◽  
Diffraction Study ◽  
Ambient Conditions ◽  
X Ray Diffraction ◽  
X Ray

Low-temperature and high-pressure polymorphs of isopropyl alcohol

CrystEngComm ◽  
2014 ◽  
Vol 16 (32) ◽  
pp. 7397-7400 ◽  
Author(s):  
Joe Ridout ◽  
Michael R. Probert
Keyword(s):  
High Pressure ◽  
Low Temperature ◽  
Single Crystal ◽  
Isopropyl Alcohol ◽  
The Other ◽  
X Ray Diffraction ◽  
X Ray

Single-crystal X-ray diffraction has been used to elucidate the structure of two polymorphs of isopropyl alcohol, one grown through in situ cryo-crystallisation, the other through high-pressure crystallisation.

The structure of chloromethyl thiocyanate, CH2ClSCN, in gas and crystalline phases

2015 ◽  
Vol 17 (24) ◽  
pp. 15805-15812 ◽  
Author(s):  
Y. Berrueta Martínez ◽  
L. S. Rodríguez Pirani ◽  
M. F. Erben ◽  
C. G. Reuter ◽  
Y. V. Vishnevskiy ◽  
...  
Keyword(s):  
Electron Diffraction ◽  
Low Temperature ◽  
Single Crystal ◽  
Gas Phase ◽  
Solid Phase ◽  
Gas Electron Diffraction ◽  
X Ray Diffraction ◽  
X Ray ◽  
Conformational Properties

The structural and conformational properties of chloromethyl thiocyanate, CH2ClSCN, were studied in the solid phase and in the gas phase usingin situlow-temperature single-crystal X-ray diffraction experiments (XRD) and gas electron diffraction (GED), respectively.

scholarly journals Low-Temperature Crystal Chemistry of Hingganite-(Y), from the Wanni Glacier, Switzerland

Minerals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 322 ◽  
Author(s):  
Liudmila Gorelova ◽  
Oleg Vereshchagin ◽  
Stéphane Cuchet ◽  
Vladimir Shilovskikh ◽  
Dmitrii Pankin
Keyword(s):  
Thermal Expansion ◽  
Low Temperature ◽  
Single Crystal ◽  
Layer Plane ◽  
X Ray Diffraction ◽  
Wavelength Dispersive Spectroscopy ◽  
X Ray ◽  
Thermal Expansion Anisotropy ◽  
High Thermal Expansion

Hingganite from the Wanni glacier (Switzerland) was studied by means of energy dispersive and wavelength-dispersive spectroscopy, Raman spectroscopy, and low-temperature single-crystal X-ray diffraction. According to its chemical composition, the investigated mineral should be considered as hingganite-(Y). It showed a relatively high content of Gd, Dy, and Er and had limited content of lighter rare-earth element (REE), which is typical for Alpine gadolinite group minerals. The most intense Raman bands were 116, 186, 268, 328, 423, 541, 584, 725, 923, 983, 3383, and 3541 cm−1. Based on data of low-temperature [(−173)–(+7) °C] in situ single-crystal X-ray diffraction, it was shown that the hingganite-(Y) crystal structure was stable in the studied temperature range and no phase transitions occurred. Hingganite-(Y) demonstrated low volumetric thermal expansion (αV = 9(2) × 10−6 °C−1) and had a high thermal expansion anisotropy up to compression along one of the directions in the layer plane. Such behavior is caused by the shear deformations of its monoclinic unit cell.

Sign in / Sign up

Export Citation Format

Share Document