Structure refinement of Al3Zr using single-crystal X-ray diffraction, powder neutron diffraction and CBED

The triclinic crystal structure of the φ phase in the structure of the Bi2O3–PbO phase diagram has been recently solved by the synergetic use of electron and X-ray diffraction on a polycrystalline Bi8Pb5O17 sample. In the present work the problem is re-examined on the basis of powder neutron diffraction data: the structure has been confirmed and refined by the Rietveld method. The increased accuracy of the O-atom positions allowed the study of the cationic ordering in this structure by means of bond-valence calculations and charge distribution analysis. The results, confirmed by the refinement of the site occupancies, indicate that the structure is ordered to a large extent, with Bi and Pb atoms occupying preferentially different lattice sites. In this frame, the φ phase being the most ordered one in the considered region of the Bi2O3–PbO phase diagram, it should represent the thermodynamically stable low-temperature polymorph.

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Structure refinement of (Al, Zn)49Mg32-type phases by single-crystal X-ray diffraction

Materials Science and Engineering A ◽

10.1016/s0921-5093(00)01094-7 ◽

2000 ◽

Vol 294-296 ◽

pp. 327-330 ◽

Cited By ~ 27

Author(s):

W. Sun ◽

F.J. Lincoln ◽

K. Sugiyama ◽

K. Hiraga

Keyword(s):

Single Crystal ◽

Structure Refinement ◽

X Ray Diffraction ◽

X Ray

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Redetermination of Sr2PdO3 from single-crystal X-ray data

Acta Crystallographica Section E Crystallographic Communications ◽

10.1107/s2056989018017176 ◽

2019 ◽

Vol 75 (1) ◽

pp. 30-32

Author(s):

Gohil S. Thakur ◽

Hans Reuter ◽

Claudia Felser ◽

Martin Jansen

Keyword(s):

Crystal Structure ◽

Single Crystal ◽

Diffraction Data ◽

Structure Refinement ◽

Structure Type ◽

X Ray Diffraction ◽

High Quality ◽

X Ray ◽

Cell Parameters ◽

Anisotropic Displacement Parameters

The crystal structure redetermination of Sr2PdO3 (distrontium palladium trioxide) was carried out using high-quality single-crystal X-ray data. The Sr2PdO3 structure has been described previously in at least three reports [Wasel-Nielen & Hoppe (1970). Z. Anorg. Allg. Chem. 375, 209–213; Muller & Roy (1971). Adv. Chem. Ser. 98, 28–38; Nagata et al. (2002). J. Alloys Compd. 346, 50–56], all based on powder X-ray diffraction data. The current structure refinement of Sr2PdO3, as compared to previous powder data refinements, leads to more precise cell parameters and fractional coordinates, together with anisotropic displacement parameters for all sites. The compound is confirmed to have the orthorhombic Sr2CuO3 structure type (space group Immm) as reported previously. The structure consists of infinite chains of corner-sharing PdO4 plaquettes interspersed by SrII atoms. A brief comparison of Sr2PdO3 with the related K2NiF4 structure type is given.

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Accurate H-atom parameters for the two polymorphs of L-histidine at 5, 105 and 295 K

Acta Crystallographica Section B Structural Science Crystal Engineering and Materials ◽

10.1107/s205252062100740x ◽

2021 ◽

Vol 77 (5) ◽

pp. 785-800

Author(s):

Giulia Novelli ◽

Charles J. McMonagle ◽

Florian Kleemiss ◽

Michael Probert ◽

Horst Puschmann ◽

...

Keyword(s):

Neutron Diffraction ◽

Single Crystal ◽

Diffraction Data ◽

Crystal Packing ◽

Basis Sets ◽

X Ray Diffraction ◽

X Ray ◽

Refinement Method ◽

Primary Amino ◽

Precision And Accuracy

The crystal structure of the monoclinic polymorph of the primary amino acid L-histidine has been determined for the first time by single-crystal neutron diffraction, while that of the orthorhombic polymorph has been reinvestigated with an untwinned crystal, improving the experimental precision and accuracy. For each polymorph, neutron diffraction data were collected at 5, 105 and 295 K. Single-crystal X-ray diffraction experiments were also performed at the same temperatures. The two polymorphs, whose crystal packing is interpreted by intermolecular interaction energies calculated using the Pixel method, show differences in the energy and geometry of the hydrogen bond formed along the c direction. Taking advantage of the X-ray diffraction data collected at 5 K, the precision and accuracy of the new Hirshfeld atom refinement method implemented in NoSpherA2 were probed choosing various settings of the functionals and basis sets, together with the use of explicit clusters of molecules and enhanced rigid-body restraints for H atoms. Equivalent atomic coordinates and anisotropic displacement parameters were compared and found to agree well with those obtained from the corresponding neutron structural models.

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Structure Refinement of CePtSi and Hydrogenation Behavior of CePdGe, CePtSi and CePtGe

Zeitschrift für Naturforschung B ◽

10.1515/znb-2007-0423 ◽

2007 ◽

Vol 62 (4) ◽

pp. 613-616 ◽

Cited By ~ 8

Author(s):

Wilfried Hermes ◽

Ute Ch. Rodewald ◽

Bernard Chevalier ◽

Rainer Pötgena

Keyword(s):

Single Crystal ◽

Diffraction Data ◽

Structure Refinement ◽

Three Dimensional ◽

Subsequent Annealing ◽

X Ray Diffraction ◽

X Ray ◽

Hydride Formation ◽

Arc Melting ◽

Cerium Compounds

The intermetallic cerium compounds CePdGe, CePtSi, and CePtGe were synthesized from the elements by arc-melting and subsequent annealing. The structure of CePtSi was refined from single crystal X-ray diffraction data: LaPtSi-type (ordered α-ThSi2 version), 141md, a = 419.6(1) and c = 1450.0(5) pm, wR2 = 0.0490, 362 F2 values and 16 variables. The Pt-Si distances within the three-dimensional [PtSi] network are 242 pm, indicating strong Pt-Si interactions. Hydrogenation of the three compounds at 623 K and 4 MPa H2 gave no indication for hydride formation.

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H-bonding scheme in allactite: a combined single-crystal X-ray and neutron diffraction, optical absorption spectroscopy, FTIR and EPMA-WDS study

Mineralogical Magazine ◽

10.1180/minmag.2016.080.020 ◽

2016 ◽

Vol 80 (5) ◽

pp. 719-732 ◽

Cited By ~ 2

Author(s):

G. Diego Gatta ◽

Ferdinando Bosi ◽

Maria Teresa Fernandez Diaz ◽

Ulf Hålenius

Keyword(s):

Neutron Diffraction ◽

Optical Absorption ◽

Single Crystal ◽

Absorption Spectroscopy ◽

Structure Refinement ◽

Site Occupancy ◽

Optical Absorption Spectroscopy ◽

Hydroxyl Groups ◽

X Ray ◽

Bonding Scheme

AbsatractThe crystal chemistry of allactite from Långban, Värmland (Sweden) was investigated by single-crystal X-ray and neutron diffraction, optical absorption spectroscopy, Fourier-transform infra-red spectroscopy (FTIR) and electron microprobe analysis by wavelength-dispersive spectroscopy (EPMA-WDS). The optical spectra indicate the presence of Mn in valence state 2+ only. Assuming 16 O atoms per formula unit, arsenic as As5+and the (OH) content calculated by charge balance, the resulting formula based on the EPMA-WDS data is (Mn2+6.73Ca0.13Mg0.12Zn0.02)∑7.00(As5+)2.00O16H8, very close to the ideal composition Mn7(AsO4)2(OH)8. In the unpolarized FTIR spectrum of allactite, fundamental (OH)-stretching bands are observed at 3236, 3288, 3387, 3446, 3484, 3562 and 3570 cm–1, suggesting that a number of OH environments, with different hydrogen bond strengths, occur in the structure. The neutron structure refinement shows that four independent H sites occur in allactite with full site occupancy, all as members of hydroxyl groups. The complex hydrogen-bonding scheme in the allactite structure is now well defined, with at least nine hydrogen bonds energetically favourable with mono-, bi- and trifurcated configurations.

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Disordered misfit [Ca2CoO3][CoO2]1.62 structure revisited via a new intrinsic modulation

Acta Crystallographica Section B Structural Science ◽

10.1107/s0108768108001213 ◽

2008 ◽

Vol 64 (2) ◽

pp. 144-153 ◽

Cited By ~ 26

Author(s):

Hervé Muguerra ◽

Dominique Grebille ◽

Françoise Bourée

Keyword(s):

Electronic Structure ◽

Single Crystal ◽

Diffraction Experiment ◽

X Ray Diffraction ◽

Neutron Diffraction Experiment ◽

X Ray ◽

Structural Modifications ◽

Local Ordering ◽

Powder Neutron Diffraction ◽

Modulation Vector

The structure of the thermoelectric lamellar misfit cobalt oxide [Ca2CoO3][CoO2]1.62 was refined again using single-crystal X-ray diffraction data. A new commensurate intrinsic modulation was observed involving a modulation vector orthogonal to the misfit direction (⅔,0,−⅓). The five-dimensional superspace group is C2/m(1δ0)(α0γ)gm and the structure was solved using a commensurate approximation. A new model is given involving an occupation modulation of the split sites of the [CoO] layer. This [CoO] layer can be described by triple chains running along b. The residual disorder along b can then be explained by the assumption of a local ordering with two types of clusters: CoO2 and Co5O4. A powder neutron diffraction experiment confirmed the ordering evidenced by the single-crystal X-ray diffraction study, but was not sufficient by itself to deal with this double modulated scheme. The new intrinsic modulation is destroyed by partial metal substitutions in the [CoO] layer. The structural modifications of this layer directly influence the physical properties which are related to the electronic structure of the [CoO2] layers.

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