scholarly journals Synthesis and crystal structure of La21Cr8−2aAlbGe7−bC12[a= 0.22 (2) andb= 0.758 (19)]

2016 ◽  
Vol 72 (11) ◽  
pp. 1565-1568
Author(s):  
Jaskarun Pabla ◽  
Yuri Janssen ◽  
Jack W. Simonson
Keyword(s):  
Crystal Structure ◽  
Three Dimensional ◽  
Structure Type ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
Cubic Crystal ◽  
Synthesis And Crystal Structure ◽  
Geometrically Frustrated ◽  
The Face ◽  
Face Centered

Single crystals of a new multinary chromium carbide, La21Cr8−2aAlbGe7−bC12(henicosalanthanum octachromium aluminium hexagermanium dodecacarbide), were grown from an La-rich self flux and were characterized by single-crystal X-ray diffraction. The face-centered cubic crystal structure is composed of isolated and geometrically frustrated regular Cr tetrahedra that are co-centered within regular C octahedra. These mutually separated Cr4−aC6clusters are distributed throughout a three-dimensional framework of Al, Ge, and La. The title compound is isotypic with La21−δMn8X7C12andR21Fe8X7C12(R= La, Ce, Pr;X= Al, Bi, Ge, Sn, Sb, Te) and represents the first example of a Cr-based compound with this structure-type.

A partly disordered 2 × 2 × 2 – superstructure of γ-brass related phase in Mn–Ni–Zn system

2021 ◽  
Vol 236 (3-4) ◽  
pp. 71-80
Author(s):  
Sivaprasad Ghanta ◽  
Anustoop Das ◽  
Rajat Kamboj ◽  
Partha P. Jana
Keyword(s):  
Crystal Structure ◽  
High Symmetry ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
X Ray ◽  
Lattice Constants ◽  
Cubic Lattice ◽  
The Face ◽  
Face Centered ◽  
Related Phase

Abstract The T phase in the Mn–Ni–Zn system was obtained as a product of high-temperature solid-state syntheses from the loaded composition of MnxNi2−xZn11 (x = 0.2–1.5)/MnxNi15.38−xZn84.62 (x = 1.54–11.54). The crystal structure of the T phase has been explored by means of X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDS). The structures were solved in the face-centered cubic space group F 4 ‾ 3 m $F‾{4}3m$ (216) and contain 409–410 atoms/unit cell. The lattice constants were found to be a = 18.1727(2) and 18.1954(1) Å for crystals C1 and C2, respectively. The crystal structure denoted the T phase is a (2aγ)3-superstructure of the ordinary cubic γ-brass-type phase. The phase is isostructural to (Fe, Ni)Zn6.5. A “cluster” description has been used to visualize the crystal structure of the title phase. The structures have been constructed by the five distinct clusters and they are situated about the high symmetry sites of the face-centered cubic lattice. The T phase is stabilized at a valance electron concentration of 1.78, which is slightly higher than those expected for typical γ-brass Hume‐Rothery compounds.

Synthesis and crystal structure of (Ag,Pd)22Se6

2013 ◽  
Vol 28 (1) ◽  
pp. 13-17 ◽  
Author(s):  
F. Laufek ◽  
A. Vymazalová ◽  
D.A. Chareev ◽  
A.V. Kristavchuk ◽  
J. Drahokoupil ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Diffraction Data ◽  
Glass Tube ◽  
Structure Type ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
Synthesis And Crystal Structure ◽  
X Ray ◽  
Cell Parameters ◽  
Silica Glass Tube

The (Ag,Pd)22Se6 phase was synthesized from individual elements by silica glass tube technique and structurally characterized from powder X-ray diffraction data. The (Ag,Pd)22Se6 phase crystallizes in Fm$\overline3$m symmetry, unit-cell parameters: a = 12.3169(2) Å, V = 1862.55(5) Å3, Z = 4, and Dc = 10.01 g/cm3. The crystal structure of the (Ag,Pd)22Se6 phase represents a stuffed 3a.3a.3a superstructure of the Pd structure (fcc), where only 4 from 108 available octahedral holes are occupied. Its crystal structure is related to the Cr23C6 structure type.

Synthesis and Crystal Structure of Tetraphenylarsonium Pentachlorocarbonylosmate(IV), (Ph4As)[OsCl5(CO)]

1997 ◽  
Vol 52 (8) ◽  
pp. 978-980 ◽  
Author(s):  
M Höhling ◽  
W Preetz
Keyword(s):  
Crystal Structure ◽  
Complex Anion ◽  
Structure Type ◽  
Close Packing ◽  
Cation Sublattice ◽  
X Ray Diffraction ◽  
Synthesis And Crystal Structure ◽  
X Ray ◽  
Positional Disorder ◽  
Intermolecular Contacts

The structure of tetraphenylarsonium pentachlorocarbonylosmate(IV), (Ph4As)[OsCl5(CO)], the first example of a halogenocarbonyl complex with osmium in the oxidation state +IV, has been determined at 208 K by single crystal X-ray diffraction: tetragonal, space group P4/n with a = 12.821 , c = 8.084 Å, Z = 2. There are short intermolecular contacts between neighbouring anions along the tetragonal axis c and unusually large displacement ellipsoids of the carbonyl group and the four equatorial Cl ligands arising from a positional disorder of the complex anion. By analogy with a variety of reported structures of the (Ph4As)[RuNCl4] structure type this is attributed to the close packing of the cation sublattice. Compared to other monocarbonylosmates the Os-C bond of 1.94(2) Å is extraordinaryly long while the bond between Os and the trans coordinated Cl ligand of 2.286(3) Å is rather short.

The Influence of the Synthesis Method on the Formation of Phase Composition and Catalytic Centers Gd2Zr2O7

2020 ◽  
Vol 1009 ◽  
pp. 69-74
Author(s):  
Ekaterina Borisovna Markova ◽  
Alexander Genrihovich Cherednichenko ◽  
V.V. Kurilkin ◽  
J.M. Serov
Keyword(s):  
Crystal Structure ◽  
Synthesis Method ◽  
Nanocrystalline Powders ◽  
Face Centered Cubic ◽  
Cubic Crystal ◽  
Wide Range ◽  
Physicochemical Methods ◽  
Degradation Reaction ◽  
Cubic Structure ◽  
Face Centered

The influence of the type of crystal structure of complex gadolinium oxides on their catalytic activity was studied using a wide range of physicochemical methods. It was shown that the synthesized nanocrystalline powders Gd2Zr2O7 form highly symmetric face-centered cubic crystal structures. In the course of catalytic experiments, it was found that the formation of a cubic structure increases the degree of conversion of propane and the shift of cracking temperatures to a lower area. The formation of various defects contributes to the course of the dehydrogenation or degradation reaction due to the different number of catalytic centers.

scholarly journals Synthesis and Crystal Structure of the New Telluric Acid Adduct (RbCl)3·Te(OH)6

2012 ◽  
Vol 67 (1) ◽  
pp. 1-4
Author(s):  
Dirk Mahlmeister ◽  
Elisabeth Irran
Keyword(s):  
Crystal Structure ◽  
Three Dimensional ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
Tellurium Atom ◽  
Synthesis And Crystal Structure ◽  
Dimensional Network ◽  
Tricapped Trigonal Prism ◽  
Acid Adduct ◽  
Oxygen Atoms

The new telluric acid adduct (RbCl)3 ・ Te(OH)6 was prepared by dissolving RbCl and Te(OH)6 in the molar ratio of 3 : 1 in deionized water at r. t. and slow evaporation of the solvent in air. The crystal structure of the colorless crystals was determined with single-crystal X-ray diffraction (trigonal space group: R3̄c (no. 167), a = 14.4392(8), c = 10.4301(16) Å , Z = 6). In (RbCl)3 ・ Te(OH)6, the rubidium atom is surrounded by five chlorine and four oxygen atoms in form of an irregular tricapped trigonal prism. Each tellurium atom is octahedrally surrounded by six oxygen atoms. The Te(OH)6 octahedra and the RbCl5O4 polyhedra are linked to a dense three-dimensional network which is additionally strengthened by hydrogen bonds.

Controlling Aspect Ratio of Copper Group Nanowire Arrays by Electrochemical Deposition in the Nanopores of AAO

2011 ◽  
Vol 335-336 ◽  
pp. 429-432 ◽  
Author(s):  
Xiu Yu Sun ◽  
Fa Qiang Xu
Keyword(s):  
Aspect Ratio ◽  
Nanowire Arrays ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
X Ray ◽  
Anodic Aluminum ◽  
Au Nanowire ◽  
The Face ◽  
Face Centered ◽  
Xrd Patterns

Highly ordered Cu, Ag and Au nanowire arrays with high aspect ratio and highly dense self-supporting nanowire patterns of copper group were successfully prepared using cyclic voltammetry with the assistance of anodic aluminum oxide (AAO) template. The X-ray diffraction (XRD) patterns of the metal nanowries were indexed to the face-centered cubic structure. The field emission scanning electron microscope (FE-SEM) results demonstrated that the length of nanowire could be controlled by changing the electrodepositon conditions. The aspect ratio of nanowire arrays can be tuned.

Novel Nanohybrids Derived from the Attachment of FePt Nanoparticles on Carbon Nanotubes

2008 ◽  
Vol 8 (11) ◽  
pp. 5942-5951 ◽  
Author(s):  
Theodoros Tsoufis ◽  
Aphrodite Tomou ◽  
Dimitrios Gournis ◽  
Alexios P. Douvalis ◽  
Ioannis Panagiotopoulos ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Carbon Nanotubes ◽  
Particle Size ◽  
Fept Nanoparticles ◽  
Face Centered Cubic ◽  
Magnetization Measurements ◽  
Hybrid Sample ◽  
The Face ◽  
Face Centered ◽  
Mwcnts Surface

Multiwalled carbon nanotubes (MWCNTs) were used as nanotemplates for the dispersion and stabilization of FePt nanoparticles (NPs). Pre-formed capped FePt NPs were connected to the MWCNTs external surface via covalent binding through organic linkers. Free FePt NPs and MWCNTs-FePt hybrids were annealed in vacuum at 700 °C in order to achieve the L10 ordering of the FePt phase. Both as prepared and annealed samples were characterized and studied using a combination of experimental techniques, such as Raman and Mössbauer spectroscopies, powder X-ray Diffraction (XRD), magnetization and transmittion electron microscopy (TEM) measurements. TEM measurements of the hybrid sample before annealing show that a fine dispersion of NPs along the MWCNTs surface is achieved, while a certain amount of free particles attached to each other in well connected dense assemblies of periodical or non-periodical particle arrangements is also observed. XRD measurements reveal that the FePt phase has the face-centered cubic (fcc) disordered crystal structure in the as prepared samples, which is transformed to the face-centered tetragonal (fct) L10 ordered crystal structure after annealing. An increase in the average particle size is observed after annealing, which is higher for the free NPs sample. Superparamagnetic phenomena due to the small FePt particle size are observed in the Mössbauer spectra of the as prepared samples. Mössbauer and magnetization measurements of the MWCNTs-FePt hybrids sample reveal that the part of the FePt particles attached to the MWCNTs surface shows superparamagnetic phenomena at RT even after the annealing process. The hard magnetic L10 phase characteristics are evident in the magnetization measurements of both samples after annealing, with the coercivity of the hybrid sample over-scaling that of the free NPs sample by a factor of 1.25.

Magnetic Properties and Morphology of the Cobalt Particles Prepared in Different Liquid Solvent

2013 ◽  
Vol 749 ◽  
pp. 192-197
Author(s):  
Xue Min Huang ◽  
Quan Sheng Wang ◽  
Ying Liu ◽  
Xiu Chen Zhao ◽  
Shu Lai Wen
Keyword(s):  
Crystal Structure ◽  
Magnetic Properties ◽  
Ethylene Glycol ◽  
Water System ◽  
Cubic Phase ◽  
Water Mixture ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
The Difference ◽  
Face Centered

The two kinds of flower-like ultrafine cobalt particles were prepared by reducing cobalt chloride (CoCl2·6H2O) with hydrazine hydrate (N2H4·H2O) under ultrasonic and microwave radiation, in which ethanol-water or ethylene glycol-water mixture was used as solvent. The morphology, crystal structure and magnetic properties of the as-prepared particles were characterized by scanning electron microscope (SEM), x-ray diffraction pattern (XRD) and vibrating sample magnetometer (VSM). The results show that the petals of the flower-like cobalt particles prepared in the ethanol-water system were dendritic, while the petals of the flower-like cobalt particles prepared in the ethylene glycol-water system were sword-like. The crystal structure of cobalt particles prepared in the two kinds of systems both consisted of hexagonal close-packed cubic phase and face-centered cubic phase, but the relative content was different. The saturation magnetization of the cobalt particles with dendritic petals and the cobalt particles with sword-like petals was the same approximately, but their coercivity was greatly different (the difference in value about 7184.14Am-1), which might be attributed to the magnetocrystalline anisotropy and shape anisotropy.

scholarly journals Synthesis, crystal structure and charge-distribution validation of a new alluaudite-type phosphate, Na2.22Mn0.87In1.68(PO4)3

2020 ◽  
Vol 76 (8) ◽  
pp. 1369-1372
Author(s):  
Abdessalem Badri ◽  
Inmaculada Alvarez-Serrano ◽  
María Luisa López ◽  
Mongi Ben Amara
Keyword(s):  
Crystal Structure ◽  
Single Crystals ◽  
Three Dimensional ◽  
Structure Type ◽  
X Ray Diffraction ◽  
Flux Method ◽  
X Ray ◽  
Coordination Numbers ◽  
Dimensional Network ◽  
Anionic Framework

Na2.22Mn0.87In1.68(PO4)3, sodium manganese indium tris(phosphate) (2.22/0.87/1.68), was obtained in the form of single crystals by a flux method and was structurally characterized by single-crystal X-ray diffraction. The compound belongs to the alluaudite structure type (space group C2/c) with general formula X(2)X(1)M(1)M(2)2(PO4)3. The X(2) and X(1) sites are partially occupied by sodium [occupancy 0.7676 (17) and 1/2] while the M(1) and M(2) sites are fully occupied within a mixed distribution of sodium/manganese(II) and manganese(II)/indium, respectively. The three-dimensional anionic framework is built up on the basis of M(2)2O10 dimers that share opposite edges with M(1)O6 octahedra, thus forming infinite chains extending parallel to [10\overline{1}]. The linkage between these chains is ensured by PO4 tetrahedra through common vertices. The three-dimensional network thus constructed delimits two types of hexagonal channels, resulting from the catenation of M(2)2O10 dimers, M(1)O6 octahedra and PO4 tetrahedra through edge- and corner-sharing. The channels are occupied by Na+ cations with coordination numbers of seven and eight.

scholarly journals Preparation and Characterization of porous Carbon/Nickel Nanofibers for Supercapacitor

2013 ◽  
Vol 8 (4) ◽  
pp. 155892501300800 ◽  
Author(s):  
Dawei Gao ◽  
Lili Wang ◽  
Xin Xia ◽  
Hui Qiao ◽  
Yibing Cai ◽  
...  
Keyword(s):  
Carbon Nanofibers ◽  
Porous Carbon ◽  
Composite Nanofibers ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
Nickel Particles ◽  
The Face ◽  
Embedded Particles ◽  
Face Centered

Two polymer solutions of polyacrylonitrile, polyvinyl pyrrolidone, and Ni(CH3COOH)2 in dimethylformamide were electrospun into ternary composite nanofibers, followed by stabilization and carbonization processes to obtain porous carbon/nickel composite nanofibers with diameters of 100–200 nm. The study revealed that carbon/nickel composite nanofibers were successfully prepared, which allowed nickel particles with diameters of 20–70 nm to be uniformly distributed in the carbon nanofibers. It was also observed that the fibrous structures with particles embedded formed and the fibers broke into shorter fibers after sintering. X-ray diffraction indicated that embedded particles crystallized with the face centered cubic structure. The Brunauer-Emmett-Teller analysis revealed that carbon/nickel composite nanofibers with meso-pores possessed larger specific surface area than that of carbon nanofibers. The specific capacitance of the composite nanofiber electrode was as high as 103.8 F/g and showed stable cyclicity (73.8%).

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