| 1. |
|
|
| 2. |
- Laniel, Dominique, et al.
(författare)
-
Synthesis, crystal structure and structure-property relations of strontium orthocarbonate, Sr2CO4
- 2021
-
Ingår i: Acta Crystallographica. Section B. - : International Union of Crystallography. - 2052-5192 .- 2052-5206. ; 77, s. 131-137
-
Tidskriftsartikel (refereegranskat)abstract
- Carbonates containing CO4 groups as building blocks have recently been discovered. A new orthocarbonate, Sr2CO4 is synthesized at 92 GPa and at a temperature of 2500 K. Its crystal structure was determined by in situ synchrotron single-crystal X-ray diffraction, selecting a grain from a polycrystalline sample. Strontium orthocarbonate crystallizes in the orthorhombic crystal system (space group Pnma) with CO4, SrO9 and SrO11 polyhedra as the main building blocks. It is isostructural to Ca2CO4. DFT calculations reproduce the experimental findings very well and have, therefore, been used to predict the equation of state, Raman and IR spectra, and to assist in the discussion of bonding in this compound.
|
|
| 3. |
- Makarova, Irina, et al.
(författare)
-
Crystal structure, hydrogen bonds and thermal transformations of superprotonic conductor Cs6(SO4)3(H3PO4)4
- 2021
-
Ingår i: Acta Crystallographica. Section B. - : International Union Of Crystallography. - 2052-5192 .- 2052-5206. ; 77:2, s. 266-274
-
Tidskriftsartikel (refereegranskat)abstract
- Crystals of Cs-6(SO4)(3)(H3PO4)(4) belong to the family of alkali metal acid salts that show a high protonic conductivity at relatively low temperatures. Such properties make superprotonic crystals an excellent choice for the study of the influence of the hydrogen subsystem on the physicochemical properties and promising materials for energy-efficient technologies. Single crystals of Cs-6(SO4)(3)(H3PO4)(4) were studied by neutron diffraction methods, optical polarization microscopy, scanning electron microscopy and energy-dispersive X-ray spectroscopy. Neutron diffraction studies made it possible to determine the positions of all the atoms with high accuracy, including the H atom on a hydrogen bond characterized by a single-minimum potential, to confirm the chemical composition of the Cs-6(SO4)(3)(H3PO4)(4) crystals and their cubic symmetry in low- and high-temperature phases, and to draw conclusions about the three-dimensional system of hydrogen bonds, which is fundamentally different in comparison with other superprotonic compounds. Based on the experimental data obtained, crystal transformations with temperature changes are reported, and the stability of the chemical composition is shown.
|
|
| 4. |
- Soliman, S.M., et al.
(författare)
-
Towards the chemical control of molecular packing: syntheses and crystal structures of three trans-[NiL4(NCS)2] complexes
- 2014
-
Ingår i: Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materials. - 2052-5206 .- 2052-5192. ; 70:1, s. 115-125
-
Tidskriftsartikel (refereegranskat)abstract
- Three nickel(II) isothiocyanato complexes of the formulatrans-[NiL4(NCS)2] (L = ethylisonicotinate, methylisonicotinateand 4-benzoylpyridine) have been prepared: [Ni(ethylisonicotinate)4(NCS)2] (I), [Ni(methylisonicotinate)4(NCS)2](II) and [Ni(4-benzoylpyridine)4(NCS)2] (III). All threecomplexes are monomeric and have a distorted octahedralgeometry around NiII. Despite their apparent molecularsimilarity, the crystal density of (III) (1.454 g cm 3) issignificantly higher than that of (I) and (II) (both1.408 g cm 3), suggesting that the molecular packing is mostefficient in (III). A study of the molecular Hirshfeld surfaces,together with density functional theory (DFT) calculations,provide insights into the origin of the molecular packingfeatures, and it is suggested that the greater crystal density of(III) results from smaller intermolecular electrostatic repulsions.
|
|
| 5. |
- Herzberg, Mikkel, et al.
(författare)
-
The structure of magnesium stearate trihydrate determined from a micrometre-sized single crystal using a microfocused synchrotron X-ray beam
- 2023
-
Ingår i: Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materials. - 2052-5192. ; 79, s. 330-335
-
Tidskriftsartikel (refereegranskat)abstract
- Crystalline magnesium stearate has been extensively used as an additive in pharmaceutical and other industries for decades. However, the lack of suitably large crystals has hindered the determination of the crystal structure and thereby a more fundamental understanding of the structure-functionality relationship. Presented here is the structure of magnesium stearate trihydrate as determined from X-ray diffraction data of a micrometre-sized single crystal measured at a fourth-generation synchrotron facility. Despite the small size of the single crystals and the weak diffraction, it was possible to determine the positions of the non-hydrogen atoms reliably. Periodic dispersion-corrected density functional theory calculations were used to obtain the positions of the hydrogen atoms playing an important role in the overall organization of the structure via a hydrogen-bond network.
|
|
| 6. |
- Jørgensen, Mads R V, et al.
(författare)
-
Neutron and X-ray investigations of the Jahn-Teller switch in partially deuterated ammonium copper Tutton salt, (NH4)2[Cu(H2O)6](SO4)2
- 2017
-
Ingår i: Acta Crystallographica. Section B: Structural Science, Crystal Engineering and Materials. - 2052-5192. ; 73:1, s. 87-93
-
Tidskriftsartikel (refereegranskat)abstract
- The structural phase transition accompanied by a Jahn-Teller switch has been studied over a range of H/D ratios in (NH4)2[Cu(H2O)6](SO4)2 (ACTS). In particular, single-crystal neutron diffraction investigations of crystals with deuteration in the range 50 to 82% are shown to be consistent with previous electron paramagnetic resonance (EPR) experiments exhibiting a phase boundary at 50% deuteration under ambient pressure. Polycrystalline samples show that the two phases can co-exist. In addition, single-crystal neutron and polycrystalline X-ray diffraction pressure experiments show a shift to lower pressure at 60% deuteration versus previous measurements at 100% deuteration.
|
|
| 7. |
- Koley, Biplab, et al.
(författare)
-
Structure and stability of γ1-AuZn2.1 : A γ-brass-related complex phase in the Au-Zn System
- 2020
-
Ingår i: Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materials. - 2052-5192. ; 76, s. 1109-1116
-
Tidskriftsartikel (refereegranskat)abstract
- γ1-AuZn2.1 in the Au-Zn binary system has been synthesized and its structure analyzed by single-crystal X-ray diffraction. It crystallizes in the trigonal space group P31m (No. 157) with ∼227 atoms per unit cell and represents a 3a × 3a × c superstructure of rhombohedrally distorted γ-Au5-x Zn8+y. The structure is largely tetrahedrally closed packed. The formation of γ1-AuZn2.1 can be understood within the framework of a Hume-Rothery stabilization mechanism with a valence electron concentration of 1.68 e/a (valence electrons per atom).
|
|
| 8. |
- Pistor, Paul, et al.
(författare)
-
Structure reinvestigation of α-, β- And γ-In2S3
- 2016
-
Ingår i: Acta Crystallographica. Section B: Structural Science, Crystal Engineering and Materials. - 2052-5192. ; 72, s. 410-415
-
Tidskriftsartikel (refereegranskat)abstract
- Semiconducting indium sulfide (In2S3) has recently attracted considerable attention as a buffer material in the field of thin film photovoltaics. Compared with this growing interest, however, detailed characterizations of the crystal structure of this material are rather scarce and controversial. In order to close this gap, we have carried out a reinvestigation of the crystal structure of this material with an in situ X-ray diffraction study as a function of temperature using monochromatic synchrotron radiation. For the purpose of this study, high quality polycrystalline In2S3 material with nominally stoichiometric composition was synthesized at high temperatures. We found three modifications of In2S3 in the temperature range between 300 and 1300 K, with structural phase transitions at temperatures of 717 K and above 1049 K. By Rietveld refinement we extracted the crystal structure data and the temperature coefficients of the lattice constants for all three phases, including a high-temperature trigonal γ-In2S3 modification.
|
|
