scholarly journals Electrochemical hydrogenation, lithiation and sodiation of the GdFe2–xMx and GdMn2–xMx intermetallics

2021 ◽  
pp. 139-149
Keyword(s):  
Electrode Materials ◽  
Electrochemical Impedance ◽  
Diffraction Method ◽  
Electrochemical Characteristics ◽  
Electrochemical Hydrogenation ◽  
Hydrogen Atoms ◽  
X Ray ◽  
Cell Parameters ◽  
The Difference ◽  
Better Than

Electrochemical hydrogenation, lithiation and sodiation of the phases GdFe2–xMx and GdMn2–xMx (M=Mn, Co, Ni, Zn, and Mg) and the influence of doping components on electrochemical characteristics of electrode materials on their basis were studied using X-ray powder diffraction method, scanning electron microscopy, energy dispersive X-ray analysis, X-ray fluorescent spectroscopy, cyclic voltammetry and electrochemical impedance spectroscopy. Phase analysis showed a simple correspondence between unit cell parameters of the phases and atomic radii of doping elements. Electrode materials based on GdFe2 and GdMn2 doped with 2 at.% of Co, Ni and Mg demonstrated better hydrogen sorption properties than those doped with Mn and Zn. Corrosion resistance of the doped electrodes was also better than of the binary analogues (e.g. corrosion potential of the GdFe2-based electrode was –0.162 V whereas that of GdFe1.96Ni0.04 was –0.695 V). The capacity parameters were increased in the following ranges: Zn<Mn<Mg<Co<Ni and Zn<Fe<Mg<Co<Ni for GdFe2–xMx and GdMn2–xMx, respectively. After fifty cycles of charge/discharge, we observed the changes in surface morphology and composition of the electrode samples. In the structure of studied Laves type phases with MgCu2-type structure, the most suitable sites for hydrogen atoms are tetrahedral voids 8a. During lithiation and sodiation of the phases, the atoms of the M-component of the structure are replaced by the atoms of lithium, and the atoms of gadolinium are replaced by the atoms of sodium. This difference in interaction is due to the difference in atomic sizes of the atoms. No insertion of lithium or sodium into the structural voids of the phases was observed.

Hydrogen Behavior in NdRh3-Based Hydrides

2016 ◽  
Vol 369 ◽  
pp. 163-167
Author(s):  
Stepan Alexandrovich Lushnikov ◽  
Tatyana Victorovna Filippova
Keyword(s):  
Diffraction Method ◽  
Hydrogen Desorption ◽  
X Ray Diffraction ◽  
Hydrogen Atoms ◽  
X Ray ◽  
Cubic Lattice ◽  
Cubic Lattices ◽  
Rate Of Heating ◽  
The Difference ◽  
Two Phases

Samples of desorbed NdRh3-based hydrides have been investigated by the X-ray diffraction method. X-ray data analysis showed that the samples contain two phases with hexagonal and cubic lattices. It was revealed that proportion of these phases in the samples depends on the rate of heating before the hydrogen desorption. At high rates of the heating in the desorbed samples amount of the phase with cubic lattice increased. This behaviour of the hydrogen in hydrides can be explained by the difference in the diffusion of disordered and ordered hydrogen atoms.

The crystallography and molecular structure of 1, 8-bisdehydro-[14]annulene

1966 ◽  
Vol 290 (1420) ◽  
pp. 94-114 ◽  
Keyword(s):  
Molecular Structure ◽  
Three Dimensional ◽  
Hydrogen Atoms ◽  
Carbon Bond ◽  
X Ray ◽  
Bond Lengths ◽  
Difference Density ◽  
Carbon Carbon Bond ◽  
The Difference ◽  
Better Than

A three-dimensional X-ray analysis of the crystal and molecular structure of 1,8-bisdehydro- [14]annulene, C 14 H 10 , is described. Carbon-carbon and carbon-hydrogen bond lengths have average estimated standard deviations of 0.009 and 0.06 Ǻ respectively and are discussed in the light of molecular orbital predictions of the electron density in the molecule; the root mean square agreement between observed and calculated carbon-carbon bond lengths is better than 0.01 Ǻ. Distortions of the carbon bond angles from strict trigonal and digonal symmetry are attributed to intramolecular steric interactions between hydrogen atoms and carbon or other hydrogen atoms. An analysis of the molecular vibrations in the lattice shows the three r.m.s. translational amplitudes about the molecular symmetry axes to be 0.18, 0.19, 0.18 Ǻ, the three corresponding r.m.s. librational amplitudes being 2.9, 2.2 and 3.6°. The ‘difference' density syntheses (σ = 0.06 e/Ǻ 3 ) are discussed and the crystal structure is related to anthracene and phenanthrene, isomers of bisdehydro-[14]annulene.

scholarly journals Purification, crystallization and preliminary X-ray diffraction analysis of a hydroxycinnamoyl-CoA shikimate/quinate hydroxycinnamoyltransferase (HCT) fromCoffea canephorainvolved in chlorogenic acid biosynthesis

2012 ◽  
Vol 68 (7) ◽  
pp. 824-828 ◽  
Author(s):  
Laura A. Lallemand ◽  
James G. McCarthy ◽  
Sean McSweeney ◽  
Andrew A. McCarthy
Keyword(s):  
Structural Data ◽  
Coffea Canephora ◽  
Molecular Replacement ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cell Parameters ◽  
Key Enzyme ◽  
Substrate Specifities ◽  
Drop Technique ◽  
Better Than

Chlorogenic acids (CGAs) are a group of soluble phenolic compounds that are produced by a variety of plants, includingCoffea canephora(robusta coffee). The last step in CGA biosynthesis is generally catalysed by a specific hydroxycinnamoyl-CoA quinate hydroxycinnamoyltransferase (HQT), but it can also be catalysed by the more widely distributed hydroxycinnamoyl-CoA shikimate/quinate hydroxycinnamoyltransferase (HCT). Here, the cloning and overexpression of HCT fromC. canephorainEscherichia colias well as its purification and crystallization are presented. Crystals were obtained by the sitting-drop technique at 293 K and X-ray diffraction data were collected on the microfocus beamline ID23-2 at the ESRF. The HCT crystals diffracted to better than 3.0 Å resolution, belonged to space groupP42212 with unit-cell parametersa=b= 116.1,c= 158.9 Å and contained two molecules in the asymmetric unit. The structure was solved by molecular replacement and is currently under refinement. Such structural data are needed to decipher the molecular basis of the substrate specifities of this key enzyme, which belongs to the large plant acyl-CoA-dependent BAHD acyltransferase superfamily.

scholarly journals MSMEG_6292, a Mycobacterium smegmatis RNA polymerase secondary channel-binding protein: purification, crystallization and X-ray diffraction analysis

2018 ◽  
Vol 74 (9) ◽  
pp. 543-548
Author(s):  
Abyson Joseph ◽  
Valakunja Nagaraja ◽  
Ramanathan Natesh
Keyword(s):  
Rna Polymerase ◽  
Mycobacterium Smegmatis ◽  
Transcriptional Activity ◽  
Molecular Replacement ◽  
X Ray Diffraction ◽  
Secondary Channel ◽  
X Ray ◽  
Cell Parameters ◽  
Crystallization Method ◽  
Better Than

The transcriptional activity of RNA polymerase (RNAP) is controlled by a diverse set of regulatory factors. A subset of these regulators modulate the activity of RNAP through its secondary channel. Gre factors reactivate stalled elongation complexes by enhancing the intrinsic cleavage activity of RNAP. In the present study, the protein MSMEG_6292, a Gre-factor homologue from Mycobacterium smegmatis, was expressed heterologously in Escherichia coli and purified using standard chromatographic techniques. The hanging-drop vapour-diffusion crystallization method yielded diffraction-quality crystals. The crystals belonged to the trigonal space group P3121 (or its enantiomorph P3221), with unit-cell parameters a = b = 83.15, c = 107.07 Å, α = β = 90, γ = 120°. The crystals diffracted to better than 3.0 Å resolution. Molecular-replacement attempts did not yield any phasing models; hence, platinum derivatization was carried out with K2PtCl4 and derivative data were collected to 3.4 Å resolution.

Fabrication of Bi6Fe2Ti3O18 Ceramics by Mixed Oxide Method

2012 ◽  
Vol 730-732 ◽  
pp. 100-104
Author(s):  
Agata Lisińska-Czekaj
Keyword(s):  
Room Temperature ◽  
Ceramic Powder ◽  
Diffraction Method ◽  
Elementary Cell ◽  
X Ray Diffraction ◽  
Stoichiometric Mixture ◽  
Pressing Method ◽  
X Ray ◽  
Cell Parameters ◽  
Ceramic Samples

In the present study Bi6Fe2Ti3O18 (BFTO) ceramics has been fabricated by solid state reaction from the mixture of simple oxides viz. Bi2O3, TiO2 and Fe2O3. Stoichiometric mixture of the powders was thermally analyzed so parameters of the thermal treatment were determined. The EDS measurements have shown conservation of the chemical composition of the ceramic powder after calcination. Hot-pressing method was used for final densification of ceramic samples. The crystalline structure of the sintered samples was examined by X-ray diffraction method at room temperature. It was found that BFTO ceramics sintered at T=980 °C adopted the orthorhombic structure of Aba2 (41) space group with the following elementary cell parameters: a=5.4567(2)Å, b=49.418(2) and c=5.4826(2). Details concerning the atom’s positions are presented.

Physicochemical Characteristics of an Ultra-Thin Hydrophobic Trichlorosilanes Using SiO2 as Adhesion

2019 ◽  
Vol 796 ◽  
pp. 80-87
Author(s):  
Akinsanya Damilare Baruwa ◽  
Esther Titilayo Akinlabi ◽  
Oluseyi Philip Oladijo ◽  
Stephen Akinwale Akinlabi ◽  
Jeff Chinn
Keyword(s):  
Room Temperature ◽  
Electrochemical Impedance ◽  
Physicochemical Characteristics ◽  
Total Reflection ◽  
Attenuated Total Reflection ◽  
Natural Seawater ◽  
X Ray Diffraction ◽  
X Ray ◽  
Hydrophobic Silane ◽  
Better Than

The aim of the research is to subject the three different silanes to chemical and electrochemical investigations in other to determine the most efficient organic compound. Three types of hydrophobic silanes [Tris (Trimethylsiloxy) silyethyl] dimethylchlorosilane (Alkyl); Tridecafloro-1,1,2,2-tetrahydrooctyltrichlorosilane (FOTS) and Henicosyl-1,1,2,2-tetrahydrododecyltricholrosilane (FDDTS) are presented and investigated. The three silanes are of different composition but are deposited at the same parameters and conditions. The chemical investigation was studied through (attenuated total reflection Fourier-transform infrared (ATR-FTIR) and x-ray diffraction (XRD), while the electrochemical study was conducted through EIS using natural seawater electrolyte at room temperature. From the investigation techniques, only electrochemical impedance results show that FDDTS performed better than both Alkyl and FOTS. The chemical analysis showed the presence of hydrophobic silane on all the coated samples, and no distinction can be drawn from associated peaks.

X-ray diffraction studies of rapid cooled Al-V and Al-Fe-V alloys

2019 ◽  
Vol 1 (96 extended issue) ◽  
pp. 5-11
Author(s):  
O. Shved ◽  
S. Mudry ◽  
V. Girzhon ◽  
O. Smolyakov
Keyword(s):  
Mechanical Properties ◽  
Physical Properties ◽  
Amorphous Matrix ◽  
Diffraction Method ◽  
Ternary Alloys ◽  
X Ray Diffraction ◽  
Rapid Cooling ◽  
X Ray ◽  
Cell Parameters ◽  
Nonequilibrium Conditions

Purpose: of this paper is to deep and more complete knowledge about the features of phase and structure formation in Al-based alloys with transition metals (TM) Fe and V at rapid cooling from melt. It is known, that nonequilibrium synthesis conditions of such alloys lead to quasicrystalline, amorphous or metastable phases formation, which can significantly improve the physical-chemical properties and first of all the mechanical ones. But understanding of compositional dependences of structure features at formation under nonequilibrium conditions and the correlation of these dependences with physical properties of alloys is far to be clear. Design/methodology/approach: Structure of Al-enriched Al-V, Al-V-Fe rapid cooled alloys was studied by X-ray diffraction method. In order to estimate the influence of structural state of alloy on the mechanical properties the integral microhardness was studied by Vickers method. Findings: Two quasicrystalline icosaedral phases with different cell parameters are revealed in ternary alloys Al100-3xV2xFex (x=2-4). Increasing of transition metal content promotes the formation of phase with higher quasicell parameter embedded in amorphous matrix. With increasing of the transition elements total content from 6 up to 12 at. % the microhardness of alloys increased gradually from 867 to 3050 MPa. Research limitations/implications: Research of nonequilibrium alloys revealed crystalline structure of Al-V alloys and quasicrystalline embedded in amorphous matrix of Al-Fe-V ternary alloys. Obtained results suppose that further structure and physical properties studies of Al-Fe-V alloys will allows to find the conditions to control the producing of materials with desired properties. Practical implications: Using of rapid cooling method for synthesis of Al-enriched Al-Fe-V alloys give an opportunity to produce alloys with significantly improved mechanical properties. Originality/value: Nonequilibrium conditions of cooling allow significantly changes the structure and properties.

A comparative study of doped and un-doped sol-gel TiO2 and P25 TiO2 (photo)electrodes

2007 ◽  
Vol 55 (12) ◽  
pp. 153-160 ◽  
Author(s):  
Y. Pooarporn ◽  
A. Worayingyong ◽  
M. Wörner ◽  
P. Songsiriritthigul ◽  
A.M. Braun
Keyword(s):  
Indium Tin Oxide ◽  
Electrochemical Impedance ◽  
Anatase Phase ◽  
Sol Gel ◽  
Oxide Glass ◽  
Electrochemical Characteristics ◽  
X Ray Diffraction ◽  
X Ray ◽  
Titanium Dioxide Films ◽  
Indium Tin Oxide Glass

Doped and undoped titanium dioxide films have been deposited on indium tin oxide glass using the sol-gel technique. The percentage of rutile in the prepared TiO2, calcined at 823 K and determined by X-ray diffraction, was 23% compared to 24% of rutile in P25-TiO2. Cerium doped TiO2 showed mainly the anatase phase, as characterised by both X-ray diffraction and Raman spectroscopy. The electrochemical and photoelectrochemical properties of the films were studied by cyclic voltammetry and electrochemical impedance spectroscopy. The (photo)electrochemical characteristics of the different films are reported and discussed.

scholarly journals Growth and Characterization of Pure and Doped L-Alanine Tartrate Single Crystals

2013 ◽  
Vol 2013 ◽  
pp. 1-5 ◽  
Author(s):  
K. Rajesh ◽  
B. Milton Boaz ◽  
P. Praveen Kumar
Keyword(s):  
Single Crystals ◽  
Vickers Microhardness ◽  
Diffraction Method ◽  
Dielectric Studies ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cell Parameters ◽  
Ft Ir ◽  
Ft Ir Spectroscopy

Single crystals of pure and Lanthanum doped L-Alanine Tartrate were grown by slow evaporation method. The cell parameters were determined using single crystal X-ray diffraction method. To improve the physical properties of the LAT crystal, Lanthanum dopant was added by 2 mol%. ICP studies confirm the presence of Lanthanum in the grown LAT crystal. Transparency range of the crystal was determined using UV-VIS-NIR spectrophotometer. The functional groups of pure and doped LAT crystals were analyzed by FT-IR spectroscopy. Using Vickers microhardness tester, mechanical strength of the material was found. Dielectric studies of pure and doped LAT single crystals were carried out. The doped LAT crystal is found to have efficiency higher than that of pure LAT crystal.

Review of Residual Stress Determination and Exploitation Techniques Using X-Ray Diffraction Method

2006 ◽  
Vol 524-525 ◽  
pp. 229-234
Author(s):  
M. Belassel ◽  
J. Pineault ◽  
M.E. Brauss
Keyword(s):  
Residual Stress ◽  
Diffraction Method ◽  
Point Of View ◽  
Stress And Strain ◽  
Stress Determination ◽  
Calculation Methods ◽  
X Ray Diffraction ◽  
X Ray ◽  
True Meaning ◽  
The Difference

Although x-ray diffraction techniques have been applied to the measurement of residual stress in the industry for decades, some of the related details are still unclear to many production and mechanical testing engineers working in the field. This is because these details, specifically those associated with the transition between diffraction and mechanics, are not always emphasized in the literature. This paper will emphasize the appropriate calculation methods and the steps necessary to perform high quality residual stress measurements. Additionally, details are given regarding the difference between mechanical and x-ray elastic constants, as well as the true meaning of stress and strain from both diffraction and strain gage point of view. Cases where the material is subject to loading above the yield limit are also included.

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