scholarly journals Synthesis, crystal structure, and electrochemical hydrogenation of the La2Mg17-xMx (M = Ni, Sn, Sb) solid solutions

2021 ◽  
Vol 12 (2) ◽  
pp. 197-203
Author(s):  
Vasyl Kordan ◽  
Vitalii Nytka ◽  
Ivan Tarasiuk ◽  
Oksana Zelinska ◽  
Volodymyr Pavlyuk

The crystal structure of La2Mg17-xSnx solid solution was determined by single crystal X-ray diffraction for the first time. This phase crystallizes in hexagonal symmetry with space group P63/mmc (a = 10.3911(3), c = 10.2702(3) Å, V = 960.36(6) Å3, R1 = 0.0180, wR2 = 0.0443 for the composition La3.65Mg30Sn1.10) and is related to the structure of CeMg10.3 and Th2Ni17-types which are derivative from the CaCu5-type. A series of isotypical solid solutions La2Mg17-xMx (M = Ni, Sn, Sb, x ~0.8) was synthesized and studied by X-ray powder diffraction, energy dispersive X-ray spectroscopy and fluorescent X-ray spectroscopy. All solid solutions crystallize with the structure related to the Th2Ni17-type. The electrochemical hydrogenation confirmed the similar electrochemical behavior of all studied alloys. The amount of deintercalated hydrogen depends on the physical and chemical characteristics of doping elements and increases in the sequence Sn < Mg < Sb < Ni. The most geometrically advantageous sites are octahedral voids 6h of the initial structure, thus a coordination polyhedron for H-atom is an octahedron [HLa2(Mg,M)4].

2021 ◽  
pp. 2150407
Author(s):  
S. I. Ibrahimova

The crystal structure and thermal properties of the [Formula: see text] compound have been investigated. Structural studies were performed by X-ray diffraction at room temperature. The crystal structure of this compound was found to correspond to the hexagonal symmetry of the space group P61. Thermal properties were studied using a differential scanning calorimetry (DSC). It was found in the temperature range [Formula: see text] that thermal effects occur at temperatures [Formula: see text] and [Formula: see text]. The thermodynamic parameters of these effects are calculated.


2019 ◽  
Vol 234 (9) ◽  
pp. 613-621
Author(s):  
Marc André Althoff ◽  
Jörn Frederik Martens ◽  
Marco Reichel ◽  
Manfred Metzulat ◽  
Thomas Matthias Klapötke ◽  
...  

Abstract The molecular and single crystal structure of O,O-diethyl O-[2-(dimethylamino)ethyl] phosphorothioate oxalate, as determined by single crystal X-ray diffraction studies, is described for the first time; although this compound is well-known by industry and research from the mid-20th century. The known decomposition product of pure O,O-diethyl O-[2-(dimethylamino)ethyl] phosphorothioate could also be structurally characterized. Additionally, the compounds are characterized by recent analytical methods e.g. NMR. The findings of our study support the thesis that the isolated decomposition product must be a by-product of the thiono-thiolo rearrangement process of the title compound.


1988 ◽  
Vol 32 ◽  
pp. 609-616 ◽  
Author(s):  
D. Chandra ◽  
C. S. Barrett ◽  
D. K. Benson

AbstractAn array of molecules that is anisotropic in the extreme has been discovered in certain thermal-energy storage materials and is reported here: neopentylglycol (NPG) and NPG-rich solid solutions with pentaglycerine (PG) have a crystal structure, stable at room temperature, that consists of bimolecular chains of molecules that are all unidirectionally aligned throughout a crystal. There are hydrogen bonds between every molecule in one chain and its neighbors in that chain, but none between molecules of one chain and any molecules of the neighboring parallel chains. Thus there are strong intermolecular bonds along each chain and only weaker bonds between the chains. The structure has been determined by using modern single crystal techniques with 529 independent reflections from a crystal of NPG (C5H12O2). The structure is monoclinic with space group P21/c - C2h5. This anisotropic structure transforms to a cubic structure at higher temperatures.


2012 ◽  
Vol 67 (3) ◽  
pp. 269-271
Author(s):  
Sadiqa Firdous ◽  
Nida Hassan Ansari ◽  
Seik Weng Ngb ◽  
Sammer Yousuf ◽  
Abdul Malik

A novel furo-furan lactone 1 has been isolated as fine needles from the ethyl acetate-soluble fraction of Heliotropium eichwaldi. This is the first report of any furo-furan from the genus Heliotropium. β -Sitosterol 3-O-β -D-glucoside 2 has also been obtained for the first time from this source. The structure of 1 was elucidated by X-ray diffraction studies.


2020 ◽  
Vol 76 (12) ◽  
pp. 1211-1221
Author(s):  
Manon Mirgaux ◽  
Laurence Leherte ◽  
Johan Wouters

Indoleamine 2,3-dioxygenase 1 has sparked interest as an immunotherapeutic target in cancer research. Its structure includes a loop, named the JK-loop, that controls the orientation of the substrate or inhibitor within the active site. However, little has been reported about the crystal structure of this loop. In the present work, the conformation of the JK-loop is determined for the first time in the presence of the heme cofactor in the active site through X-ray diffraction experiments (2.44 Å resolution). Molecular-dynamics trajectories were also obtained to provide dynamic information about the loop according to the presence of cofactor. This new structural and dynamic information highlights the importance of the JK-loop in confining the labile heme cofactor to the active site.


2010 ◽  
Vol 177 ◽  
pp. 497-501
Author(s):  
Feng Rui Zhai ◽  
Zhong Zhou Yi ◽  
Qun Cai ◽  
Huan Bin Song ◽  
Li Li Zhang ◽  
...  

The modality, physical and chemical characteristics, mineralogy and distribution of particle size of coal ash were studied by modern analytic technology SEM, spectral analysis, X - ray Diffraction (XRD) and laser granularity analyzer. The test results show that the mineralogy of coal ashes is dominated mainly by mullite, quartz and hematite.The coal ash of Yang Zonghai power plant has lower content of calcium oxide and is low calcium ash.At the same time, the losing amount is low to burn.The particle diameter is small and mainly concentrates on the range of 1-40 m.


Author(s):  
Alexander M. Antipin ◽  
Natalia I. Sorokina ◽  
Olga A. Alekseeva ◽  
Alexandra N. Kuskova ◽  
Elena P. Kharitonova ◽  
...  

A single crystal of Nd5Mo3O16with lead partly substituting for neodymium, which has a fluorite-like structure, was studied by precision X-ray diffraction, high-resolution transmission microscopy and EDX microanalysis. The crystal structure is determined in the space group Pn\bar 3n. It was found that the Pb atoms substitute in part for Nd atoms in the structure and are located in the vicinity of Nd2 positions. Partial substitutions of Mo cations for Nd positions and of Nd for Mo positions in crystals of theLn5Mo3O16oxide family are corroborated by X-ray diffraction for the first time. The first experimental verification of the location of an additional oxygen ion in the voids abutting MoO4tetrahedra was obtained.


2014 ◽  
Vol 2014 ◽  
pp. 1-7
Author(s):  
Tatiana M. Savankova ◽  
Lev G. Akselrud ◽  
Lyudmyla I. Ardanova ◽  
Alexey V. Ignatov ◽  
Eugeni I. Get’man ◽  
...  

Solid solutions of Pb(8−x)Na2Smx(VO4)6O(x/2)were studied using X-ray diffraction analysis including Rietveld refinement and scanning electron microscopy and by measuring their electrical conductivity. Crystal structure of the solid solutions was refined and the solubility region0≤x≤0.2was determined for samarium substitution for lead under the scheme2Pb2++□→2Sm3++O2-. The influence of degree of substitution on the electrical conductivity of solid solutions was established.


1981 ◽  
Vol 36 (2) ◽  
pp. 161-171 ◽  
Author(s):  
Joachim Fuchs ◽  
Axel Thiele ◽  
Rosemarie Palm

Abstract Dodecatungstosilicates free of crystal water were prepared for the first time by using tetraalkylammonium as cation. The crystal structure of the tetramethylammonium a-dodeeatungstosilicate [N(CH3)4]4SiW12O40 (1) and tetrabutylammonium) β-dodecatungstosilicate, [N(C4H9)4]4SiWi2040 (2) were solved by X-ray diffraction. (1) crystallizes tetragonal in the space group 14̅ with lattice parameters a = 14.642 Å; c= 12.706 Å; (2) orthorhombic, space group P212121 with a = 29.277 Å, b = 22.181 Å and c = 15.381 Å. The differences between the two isomeric heteropolyanions are discussed, especially the distances and angles between the tungsten atoms. Comparison of characteristic differences in the vibrational spectra permits the identification of the isomeric anions.


2021 ◽  
Author(s):  
Anna Pisareva ◽  
Gennady V. Shilov ◽  
Alexander Karelin ◽  
Rostislav Pisarev ◽  
Nadezhghda Bukun ◽  
...  

Octahydrate of tetralithium salt of calix[4]sarenesulfonic acid was isolated for the first time The crystal structure of salt was determined by X-ray diffraction analysis. Compound crystallized in triclinic syngony, P-1,...


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