Diffractometric crystal centering

A general formalism for centering a single-crystal on a four-circle diffractometer, based on the setting angles of reflections, is presented. The minimum information for the determination of crystal displacement are the diffractometer setting angles of two reciprocal vectors. The method is independent of the crystallographic system and does not require prior information about the crystal lattice. The size of the radiation source, beam divergence and homogeneity are shown to be significant factors for calculating the crystal displacement from the positions of the reflections. The method is primarily designed for samples enclosed in high-pressure diamond-anvil cells and other environments obscuring visual control of the sample position; however, high accuracy of the method in most cases allows the optical centering of the crystals to be improved, particularly for irregularly shaped samples. A procedure for retrieving true lattice dimensions, by accounting for the effect of the crystal displacement from the diffractometer center, is also presented.

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In situ determination of crystal structure for high pressure phase of ZrO2 using a diamond anvil and single crystal X-ray diffraction method

Physics and Chemistry of Minerals ◽

10.1007/bf00308274 ◽

1986 ◽

Vol 13 (4) ◽

pp. 233-237 ◽

Cited By ~ 138

Author(s):

Y. Kudoh ◽

H. Takeda ◽

H. Arashi

Keyword(s):

Crystal Structure ◽

High Pressure ◽

Single Crystal ◽

Diffraction Method ◽

X Ray Diffraction ◽

X Ray ◽

Diamond Anvil ◽

Pressure Phase

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An Externally-Heated Diamond Anvil Cell for Synthesis and Single-Crystal Elasticity Determination of Ice-VII at High Pressure-Temperature Conditions

Journal of Visualized Experiments ◽

10.3791/61389 ◽

2020 ◽

Author(s):

Xiaojing Lai ◽

Feng Zhu ◽

Jin S. Zhang ◽

Dongzhou Zhang ◽

Sergey Tkachev ◽

...

Keyword(s):

High Pressure ◽

Single Crystal ◽

Diamond Anvil Cell ◽

Temperature Conditions ◽

Diamond Anvil

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Single Crystal Growth of High-Pressure Phases of Ice and Salt Hydrate Far Below the Original Melting Point by Mixing Alcohol: Crystal Structure Determination of Magnesium Chloride Heptahydrate

10.26434/chemrxiv.11345063.v2 ◽

2020 ◽

Author(s):

Keishiro Yamashita ◽

Kazuki Komatsu ◽

Hiroyuki Kagi

Keyword(s):

Crystal Structure ◽

High Pressure ◽

Crystal Growth ◽

Single Crystal ◽

Room Temperature ◽

Growth Technique ◽

Salt Hydrate ◽

X Ray

An crystal-growth technique for single crystal x-ray structure analysis of high-pressure forms of hydrogen-bonded crystals is proposed. We used alcohol mixture (methanol: ethanol = 4:1 in volumetric ratio), which is a widely used pressure transmitting medium, inhibiting the nucleation and growth of unwanted crystals. In this paper, two kinds of single crystals which have not been obtained using a conventional experimental technique were obtained using this technique: ice VI at 1.99 GPa and MgCl<sub>2</sub>·7H<sub>2</sub>O at 2.50 GPa at room temperature. Here we first report the crystal structure of MgCl2·7H2O. This technique simultaneously meets the requirement of hydrostaticity for high-pressure experiments and has feasibility for further in-situ measurements.

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Comparison between beryllium and diamond-backing plates in diamond-anvil cells: Application to single-crystal x-ray diffraction high-pressure data

Review of Scientific Instruments ◽

10.1063/1.3590776 ◽

2011 ◽

Vol 82 (5) ◽

pp. 055111 ◽

Cited By ~ 7

Author(s):

Benedetta Periotto ◽

Fabrizio Nestola ◽

Tonci Balic-Zunic ◽

Ross J. Angel ◽

Ronald Miletich ◽

...

Keyword(s):

High Pressure ◽

Single Crystal ◽

Pressure Data ◽

X Ray Diffraction ◽

Diamond Anvil Cells ◽

X Ray ◽

Diamond Anvil

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Magnetically Oriented Powder Crystal to Indexing and Structure Determination

Acta Crystallographica Section A Foundations and Advances ◽

10.1107/s2053273314084393 ◽

2014 ◽

Vol 70 (a1) ◽

pp. C1560-C1560

Author(s):

Fumiko Kimura ◽

Wataru Oshima ◽

Hiroko Matsumoto ◽

Hidehiro Uekusa ◽

Kazuaki Aburaya ◽

...

Keyword(s):

Crystal Structure ◽

Single Crystal ◽

Crystal Lattice ◽

Powder Diffraction ◽

Diffraction Method ◽

Lattice Parameters ◽

X Ray Diffraction ◽

X Ray ◽

Crystal Lattice Parameters

In pharmaceutical sciences, the crystal structure is of primary importance because it influences drug efficacy. Due to difficulties of growing a large single crystal suitable for the single crystal X-ray diffraction analysis, powder diffraction method is widely used. In powder method, two-dimensional diffraction information is projected onto one dimension, which impairs the accuracy of the resulting crystal structure. To overcome this problem, we recently proposed a novel method of fabricating a magnetically oriented microcrystal array (MOMA), a composite in which microcrystals are aligned three-dimensionally in a polymer matrix. The X-ray diffraction of the MOMA is equivalent to that of the corresponding large single crystal, enabling the determination of the crystal lattice parameters and crystal structure of the embedded microcrytals.[1-3] Because we make use of the diamagnetic anisotropy of crystal, those crystals that exhibit small magnetic anisotropy do not take sufficient three-dimensional alignment. However, even for these crystals that only align uniaxially, the determination of the crystal lattice parameters can be easily made compared with the determination by powder diffraction pattern. Once these parameters are determined, crystal structure can be determined by X-ray powder diffraction method. In this paper, we demonstrate possibility of the MOMA method to assist the structure analysis through X-ray powder and single crystal diffraction methods. We applied the MOMA method to various microcrystalline powders including L-alanine, 1,3,5-triphenyl benzene, and cellobiose. The obtained MOMAs exhibited well-resolved diffraction spots, and we succeeded in determination of the crystal lattice parameters and crystal structure analysis.

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Microporous crystal structure of labuntsovite-Fe and high-pressure behavior up to 23 GPa

Acta Crystallographica Section B Structural Science Crystal Engineering and Materials ◽

10.1107/s205252061700498x ◽

2018 ◽

Vol 74 (1) ◽

pp. 1-11 ◽

Cited By ~ 1

Author(s):

Sergey M. Aksenov ◽

Elena A. Bykova ◽

Ramiza K. Rastsvetaeva ◽

Nikita V. Chukanov ◽

Irina P. Makarova ◽

...

Keyword(s):

Crystal Structure ◽

High Pressure ◽

Single Crystal ◽

Cross Section ◽

Structure Refinement ◽

Alkaline Complex ◽

X Ray ◽

Cell Parameters ◽

Diamond Anvil ◽

The Stability

Labuntsovite-Fe, an Fe-dominant member of the labuntsovite subgroup, was first discovered in the Khibiny alkaline massif on Mt Kukisvumchorr [Khomyakov et al. (2001). Zap. Vseross. Mineral. Oba, 130, 36–45]. However, no data are published about the crystal structure of this mineral. Labuntsovite-Fe from a peralkaline pegmatite located on Mt Nyorkpakhk, in the Khibiny alkaline complex, Kola Peninsula, Russia, has been investigated by means of electron microprobe analyses, single-crystal X-ray structure refinement, and IR and Raman spectroscopies. Monoclinic unit-cell parameters of labuntsovite-Fe are: a = 14.2584 (4), b = 13.7541 (6), c = 7.7770 (2) Å, β = 116.893 (3)°; V = 1360.22 (9) Å3; space group C2/m. The structure was refined to final R 1 = 0.0467, wR 2 = 0.0715 for 3202 reflections [I > 3σ(I)]. The refined crystal chemical formula is (Z = 2): Na2K2Ba0.7[(Fe0.5Ti0.1Mg0.05)(H2O)1.3]{[Ti2(Ti1.9Nb0.1)(O,OH)4][Si4O12]2}·4H2O. The high-pressure in situ single-crystal X-ray diffraction study of the labuntsovite-Fe has been carried out in a diamond anvil cell. The labuntsovite-type structure is stable up to 23 GPa and phase transitions are not observed. Calculations using the BM3 equation of state resulted in the bulk modulus K = 72 (2) GPa, K′0 = 3.7 (2) and V 0 = 1363 (2) Å3. Compressing of the heteropolyhedral zeolite-like framework leads to the deformation of main structural units. Octahedral rods show the gradual increase of distortion and the wave-like character of rods becomes more distinct. Rod deformations result in the distortion of the silicon–oxygen ring which is not equal in different directions. Structural channels are characterized by a different ellipticity–pressure relationship: the cross-section of the largest channel I and channel II demonstrates the stability of the geometrical characteristics which practically do not depend on pressure: ∊channel I ≃ 0.85 (4) (cross-section is rather regular) and ∊channel II ≃ 0.52 (2) within the whole pressure range. However, channel III is characterized by the increasing of ellipticity with pressure (∊ = 0.40 → 0.10).

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