Low temperature neutron diffraction data for CeCo0.86Ge2

Labradorite feldspars of the plagioclase solid solution series have been known for their complicated subsolidus phase relations and enigmatic incommensurately modulated structures. Characterized by the irrationally indexed e-reflections in the diffraction pattern, e-labradorite shows the largest variation in the incommensurate ordering states among the e-plagioclase structures. The strongly ordered low-temperature e-labradorite is one of the last missing pieces of the e-plagioclase puzzle. Nine plutonic and metamorphic labradorite feldspar samples from Canada, Ukraine, Minnesota (USA), Tanzania and Greenland with compositions ranging from An52.5 to An68 were studied with single-crystal X-ray diffraction. Two crystals from Labrador, Canada, and Duluth, MN, USA, with wide enough twin lamellae were analyzed with single-crystal neutron diffraction. The incommensurately modulated structures of e-plagioclase are refined for the first time with neutron diffraction data, which confirmed that the T—O distance modulation in the low-temperature e-plagioclase results from the Al–Si ordering in the framework. Detailed configurations of the M site are also observed in the structures refined from neutron diffraction data, which were not possible to see with X-ray diffraction data. The relation between the q-vectors and the mole% An composition is revealed for the entire compositional range of e-plagioclase, from An25 to An75. The previously proposed two-trend relation depending on the cooling rate and phase transition path is confirmed. A new classification of e-plagioclase (e α, e β and e γ) is proposed based on the q-vector of the structure, which makes it an independent character from the presence/absence of density modulation. New parameters are proposed to quantify the ordering states of these complicated aperiodic structures of e-plagioclases, such as the difference between 〈T1o—O〉 and 〈T1m—O〉 at phase t = 0.2 or the normalized intensity of the (071\bar 1) reflection.

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Cryo-neutron crystallographic data collection and preliminary refinement of left-handed Z-DNA d(CGCGCG)

Acta Crystallographica Section F Structural Biology Communications ◽

10.1107/s2053230x1801066x ◽

2018 ◽

Vol 74 (10) ◽

pp. 603-609 ◽

Cited By ~ 2

Author(s):

Joel M. Harp ◽

Leighton Coates ◽

Brendan Sullivan ◽

Martin Egli

Keyword(s):

Low Temperature ◽

Data Collection ◽

Neutron Diffraction ◽

Diffraction Data ◽

Water Molecules ◽

X Rays ◽

Neutron Diffraction Data ◽

Oak Ridge ◽

Left Handed ◽

Z Dna

Crystals of left-handed Z-DNA [d(CGCGCG)]2 diffract X-rays to beyond 1 Å resolution, feature a small unit cell (∼18 × 31 × 44 Å) and are well hydrated, with around 90 water molecules surrounding the duplex in the asymmetric unit. The duplex shows regular hydration patterns in the narrow minor groove, on the convex surface and around sugar–phosphate backbones. Therefore, Z-DNA offers an ideal case to test the benefits of low-temperature neutron diffraction data collection to potentially determine the donor–acceptor patterns of first- and second-shell water molecules. Nucleic acid fragments pose challenges for neutron crystallography because water molecules are located on the surface rather than inside sequestered spaces such as protein active sites or channels. Water molecules can be expected to display dynamic behavior, particularly in cases where water is not part of an inner shell and directly coordinated to DNA atoms. Thus, nuclear density maps based on room-temperature diffraction data with a resolution of 1.6 Å did not allow an unequivocal determination of the orientations of water molecules. Here, cryo-neutron diffraction data collection for a Z-DNA crystal on the Macromolecular Neutron Diffractometer at the Spallation Neutron Source at Oak Ridge National Laboratory and the outcome of an initial refinement of the structure are reported. A total of 12 diffraction images were recorded with an exposure time of 3.5 h per image, whereby the crystal was static for each diffraction image with a 10° φ rotation between images. Initial refinements using these neutron data indicated the positions and orientations of 30 water molecules within the first hydration shell of the DNA molecule. This experiment constitutes a state-of-the-art approach and is the first attempt to our knowledge to determine the low-temperature neutron structure of a DNA crystal.

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Low-temperature crystal structure of the unconventional spin-triplet superconductor UTe2 from single-crystal neutron diffraction

Acta Crystallographica Section B Structural Science Crystal Engineering and Materials ◽

10.1107/s2052520619016950 ◽

2020 ◽

Vol 76 (1) ◽

pp. 137-143 ◽

Cited By ~ 4

Author(s):

Vladimir Hutanu ◽

Hao Deng ◽

Sheng Ran ◽

Wesley T. Fuhrman ◽

Henrik Thoma ◽

...

Keyword(s):

Crystal Structure ◽

Low Temperature ◽

Neutron Diffraction ◽

Single Crystal ◽

Diffraction Data ◽

Linear Thermal Expansion ◽

The Body ◽

Superconducting Transition ◽

Neutron Diffraction Data ◽

Spin Triplet

The crystal structure of a new superconductor UTe2 has been investigated using single-crystal neutron diffraction for the first time at the low temperature (LT) of 2.7 K, just above the superconducting transition temperature of ∼1.6 K, in order to clarify whether the orthorhombic structure of type Immm (No. 71), reported for the room-temperature (RT) structure persists down to the superconducting phase and can be considered as a parent symmetry for the development of spin-triplet superconductivity. In contrast to the previously reported phase transition at about 100 K [Stöwe (1996). J. Solid State Chem. 127, 202–210], our high-precision LT neutron diffraction data show that the body-centred RT symmetry is indeed maintained down to 2.7 K. No sign of a structural change from RT down to 2.7 K was observed. The most significant change depending on temperature was observed for the U ion position and the U–U distance along the c direction, implying its potential importance as a magnetic interaction path. No magnetic order could be deduced from the neutron diffraction data refinement at 2.7 K, consistent with bulk magnetometry. Assuming normal thermal evolution of the lattice parameters, moderately large linear thermal expansion coefficients of about α = 2.8 (7) × 10−5 K−1 are estimated.

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Low temperature magnetic behaviour of CuFeS2 from neutron diffraction data

Journal of Magnetism and Magnetic Materials ◽

10.1016/s0304-8853(96)00252-1 ◽

1996 ◽

Vol 162 (2-3) ◽

pp. 347-354 ◽

Cited By ~ 32

Author(s):

J.C. Woolley ◽

A.-M. Lamarche ◽

G. Lamarche ◽

M. Quintero ◽

I.P. Swainson ◽

...

Keyword(s):

Low Temperature ◽

Neutron Diffraction ◽

Diffraction Data ◽

Magnetic Behaviour ◽

Neutron Diffraction Data

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Crystal structure of low-temperature form of bismuth vanadium oxide determined by rietveld refinement of X-ray and neutron diffraction data (α - Bi4V2O11)

Materials Research Bulletin ◽

10.1016/0025-5408(94)90138-4 ◽

1994 ◽

Vol 29 (2) ◽

pp. 175-184 ◽

Cited By ~ 55

Author(s):

O. Joubert ◽

A. Jouanneaux ◽

M. Ganne

Keyword(s):

Crystal Structure ◽

Low Temperature ◽

Neutron Diffraction ◽

Vanadium Oxide ◽

Rietveld Refinement ◽

Diffraction Data ◽

Neutron Diffraction Data ◽

X Ray ◽

Temperature Form

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Low Temperature Magnetic Structure of CrNiAs

Materials Science Forum ◽

10.4028/www.scientific.net/msf.443-444.379 ◽

2004 ◽

Vol 443-444 ◽

pp. 379-382 ◽

Cited By ~ 4

Author(s):

M. Bacmann ◽

Daniel Fruchart ◽

A. Koumina ◽

P. Wolfers

Keyword(s):

Low Temperature ◽

Neutron Diffraction ◽

Magnetic Structure ◽

Diffraction Data ◽

Magnetic Moments ◽

Neutron Diffraction Data ◽

Temperature Range ◽

Powder Neutron Diffraction ◽

Integrated Intensity ◽

Typical Satellite

The magnetic structure of CrNiAs was determined from magnetisation and powder neutron diffraction experiments. In the 110-182 K temperature range, the compound is ferromagnetic, resulting mainly from the Cr moment of 1.25(5) μB. Below 110 K, neutron diffraction data reveals typical satellite reflections which propagation vector is 0.228 c*. A model of oscillating magnetic moments was refined from the integrated intensity of the few additional lines.

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