scholarly journals Synthesis, Crystal Structure and Magnetic Properties of Bixbyite-type Vanadium Oxide Nitrides

2009 ◽  
Vol 64 (3) ◽  
pp. 281-286 ◽  
Author(s):  
Suliman Nakhal ◽  
Wilfried Hermes ◽  
Thorsten Ressler ◽  
Rainer Pöttgen ◽  
Martin Lerch
Keyword(s):  
Crystal Structure ◽  
Vanadium Oxide ◽  
Magnetic Ordering ◽  
Vanadium Oxides ◽  
Detectable Amount ◽  
X Ray Diffraction ◽  
X Ray ◽  
Vanadium Sulfide ◽  
Structure Result ◽  
X Ray Absorption

Ammonolysis of vanadium sulfide leads to the formation of bixbyite-type vanadium oxide nitrides. Small amounts of nitrogen incorporated in the structure result in the stabilization of the bixbyite type not known for vanadium oxides. The crystal structure was investigated using X-ray diffraction and X-ray absorption spectroscopy. At temperatures above 550 °C the powders decompose to corundumtype V2O3 containing no detectable amount of nitrogen. Below 39 K magnetic ordering is observed.

PL Properties of (Ba, Ca)2( Si, P)O4: Eu Synthesized by Various Annealing and Cooling Process

2021 ◽  
Vol 1016 ◽  
pp. 231-235
Author(s):  
Shota Ando ◽  
Hiromi Nakano ◽  
Koichiro Fukuda
Keyword(s):  
Crystal Structure ◽  
X Ray Diffraction ◽  
High Concentration ◽  
Slow Cooling ◽  
X Ray ◽  
Host Materials ◽  
Emission Color ◽  
Increasing Temperature ◽  
X Ray Absorption ◽  
Color Emission

We have been investigating the series of P doped Ca2SiO4 (C2S) using Eu2+ or Eu3+ as activator with various colors. The crystal structure of C2S is particularly easily controlled by heating because the established polymorphs of C2S are, in the order of increasing temperature, γ, β, α’L, α’H, and α. In order to control the crystal structure, the phosphors were synthesized and then annealed at temperatures 1473 K-1773 K. The crystal structures and PL properties were compared between slow cooling and quenching (cooled in water). We found unique phenomena when the phosphors were treated by quenching process. In the case of (Ba1-xCax)2(Si0.94P0.06)O4:Eu3+ ( 0.25 ≤ x ≤ 1), color emission changed from red to blue-white for the phosphor with a high concentration of Ba and quenched at 1773 K. In general, Eu3+ doped phosphors showed the red emission color in any host materials. However, Ba-included and quenched-treatment phosphors emitted a bright white color. The mechanism and relationship between the PL property and crystal structure were characterized carefully using X-ray diffraction, electron microscope and X-ray absorption fine structure.

Hydrothermal Syntheses and Crystal Structures of Two New Mixed-valence Vanadium Oxides [Ni(en)2(H2O)2][Ni(en)3]2[V16O38Cl] · 3(H2O) and (H3O)2V3O8

2010 ◽  
Vol 65 (12) ◽  
pp. 1451-1456 ◽  
Author(s):  
Xing Liu ◽  
Xian-Hong Yin ◽  
Feng Zhang
Keyword(s):  
Vanadium Oxide ◽  
Single Crystal ◽  
Interlayer Space ◽  
Mixed Valence ◽  
Vanadium Oxides ◽  
Cluster Anions ◽  
X Ray Diffraction ◽  
Reaction Conditions ◽  
X Ray ◽  
Molar Ratios

Two vanadium oxides [Ni(en)2(H2O)2][Ni(en)3]2[V16O38Cl] ・3(H2O) (1) (en = ethylenediamine) and (H3O)2 V3O8 (2) were hydrothermally synthesized and characterized by single-crystal X-ray diffraction. 1 consists of [Ni(en)2(H2O)2]2+ and [Ni(en)3]2+ cations, discrete [V16O38Cl]6− cluster anions and H2O molecules, while 2 consists of anionic mixed-valent V5+/V4+ vanadium oxide layers constructed from pairs of corner-sharing VVO4 tetrahedra and VIVO5 square pyramids, with H3O+ cations occupying the interlayer space. Both 1 and 2 were synthesized under the same reaction conditions but with different V/Ni molar ratios, which shows that the reactant stoichiometry of the system plays a key role in the formation of different structures in the products.

Chemical Bonding and Physical Properties of Yb5Bi3

2007 ◽  
Vol 62 (7) ◽  
pp. 935-940 ◽  
Author(s):  
Ying Liang ◽  
Raul Cardoso-Gil ◽  
Walter Schnelle ◽  
Marcus Schmidt ◽  
Jing Tai Zhao ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Chemical Bonding ◽  
Binary Compound ◽  
X Ray Diffraction ◽  
X Ray ◽  
Band Structure Calculations ◽  
Valence States ◽  
Effective Valence ◽  
X Ray Absorption ◽  
Structure Calculations

Abstract The binary compound Yb5Bi3 was synthesized by reaction of the elements in a sealed Ta container. Its crystal structure was determined from single-crystal X-ray diffraction data: β -Yb5Sb3-type, space group Pnma, Pearson code oP32, a = 12.6375(6), b = 9.7243(4), c = 8.4117(5) Å, V = 1033.72(9) Å3, Z = 4, Rgt(F) = 0.028, wRref(F2) = 0.069, T = 290 K. Band structure calculations and analysis of the chemical bonding suggest mainly ionic interactions in the crystal structure and a possible presence of ytterbium in two valence states Yb2+ and Yb3+. The magnetization measurements showed that at low temperatures Yb5Bi3 contains ytterbium exclusively in the 4f14 configuration without fluctuations to the Yb 4f13 configuration up to 400 K. From the Yb-LIII X-ray absorption spectroscopy data the effective valence of ytterbium was found to be 2.11 (89% of Yb in 4f14 configuration).

The Structure and Properties of Two New Silicotitanate Zeolites

1996 ◽  
Vol 465 ◽  
Author(s):  
M. L. Balmer ◽  
Y. Su ◽  
I. E. Grey ◽  
A. Santoro ◽  
R. S. Roth ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Ring Opening ◽  
Charge Compensation ◽  
Structure And Properties ◽  
Framework Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Covalently Bonded ◽  
X Ray Absorption ◽  
Open Framework Structure

ABSTRACTTwo new zeolitic crystalline phases with stoichiometry, CSTiSi2O6.5 and CS2TiSi6O15, have been discovered. CSTiSi2O6.5 has a crystal structure isomorphous to the mineral pollucite, CsAlSi2O6, with Ti+4 replacing Al+3. This replacement requires a mechanism for charge compensation. A combination of techniques including neutron diffraction, single crystal x-ray diffraction and x-ray absorption spectroscopy have revealed that eight extra oxygens are present per unit cell Cs2TiSi2O6.5 as compared to pollucite. As a result of the extra oxygen, the titanium coordination geometry is five-fold. Pentacoordinate titanium and tetrahedral silicon form a network structure with Cs residing in cages formed by the network. The crystal structure of Cs2TiSi6O15 is unique, with titanium octahedra and silicon tetrahedra forming an open framework structure with the Cs residing in large cavities. The largest covalently bonded ring opening to the Cs cavities in both compounds are smaller than a Cs ion, revealing that the Cs ion has minimal mobility in the structure. Cesium leach rates for both compounds are lower than or comparable to borosilicate glass.

Crystal structure of an inclusion complex between chiral monoaza-15-crown-5 and S(–)-1-phenyl-ethyl ammonium percholorate

2003 ◽  
Vol 218 (5) ◽  
Author(s):  
Süheyla Özbey ◽  
F. B. Kaynak ◽  
M. Toğrul ◽  
N. Demirel ◽  
H. Hoşgören
Keyword(s):  
Crystal Structure ◽  
Inclusion Complex ◽  
Single Crystal ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
New Type

AbstractA new type of inclusion complex, S(–)-1 phenyl ethyl ammonium percholorate complex of R-(–)-2-ethyl - N - benzyl - 4, 7, 10, 13 - tetraoxa -1- azacyclopentadecane, has been prepared and studied by NMR, IR and single crystal X-ray diffraction techniques. The compound crystallizes in space group

Physicochemical and Catalytic Properties of Spinels Formed by Solid-Solid Interaction Between Fe2O3and V2O5

1996 ◽  
Vol 61 (8) ◽  
pp. 1131-1140 ◽  
Author(s):  
Abd El-Aziz Ahmed Said
Keyword(s):  
Vanadium Oxide ◽  
Active Sites ◽  
Catalyst Surface ◽  
Catalytic Properties ◽  
Flow System ◽  
Oxide Catalysts ◽  
X Ray Diffraction ◽  
Selective Catalyst ◽  
X Ray ◽  
Solid Catalysts

Vanadium oxide catalysts doped or mixed with 1-50 mole % Fe3+ ions were prepared. The structure of the original samples and those calcined from 200 up to 500 °C were characterized by TG, DTA, IR and X-ray diffraction. The SBET values and texture of the solid catalysts were investigated. The catalytic dehydration-dehydrogenation of isopropanol was carried out at 200 °C using a flow system. The results obtained showed an observable decrease in the activity of V2O5 on the addition of Fe3+ ions. Moreover, Fe2V4O13 is the more active and selective catalyst than FeVO4 spinels. The results were correlated with the active sites created on the catalyst surface.

Crystal Forms of Semisynthetic Ergot Alkaloid Terguride

2002 ◽  
Vol 67 (4) ◽  
pp. 479-489 ◽  
Author(s):  
Michal Hušák ◽  
Bohumil Kratochvíl ◽  
Ivana Císařová ◽  
Ladislav Cvak ◽  
Alexandr Jegorov ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Ergot Alkaloid ◽  
Simplified Model ◽  
Quantum Mechanical ◽  
Quantum Mechanical Calculations ◽  
X Ray Diffraction ◽  
Torsion Angles ◽  
Crystal Forms ◽  
X Ray ◽  
Independent Molecules

Two new structures of semisynthetic ergot alkaloid terguride created by unusual number of symmetry-independent molecules were determined by X-ray diffraction methods at 150 K. Form A (monoclinic, P212121, Z = 12) contains three symmetry-independent terguride molecules and two molecules of water in the asymmetric part of the unit cell. The form CA (monoclinic, P21, Z = 8) is an anhydrate remarkable by the presence of four symmetry-independent molecules in the crystal structure. Conformations of twelve symmetry-independent molecules that were found in four already described terguride structures are compared with torsion angles obtained by ab initio quantum-mechanical calculations for the simplified model of N-cyclohexyl-N'-diethylurea.

scholarly journals High-pressure synthesis and crystal structure of the mixed-cation borate Ga4In4B15O33(OH)3

2019 ◽  
Vol 74 (4) ◽  
pp. 357-363
Author(s):  
Daniela Vitzthum ◽  
Hubert Huppertz
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
High Temperature ◽  
Diffraction Data ◽  
X Ray Diffraction ◽  
Synthesis And Crystal Structure ◽  
X Ray ◽  
Mixed Cation ◽  
High Pressure High Temperature ◽  
Pressure Synthesis

AbstractThe mixed cation triel borate Ga4In4B15O33(OH)3 was synthesized in a Walker-type multianvil apparatus at high-pressure/high-temperature conditions of 12.5 GPa and 1300°C. Although the product could not be reproduced in further experiments, its crystal structure could be reliably determined via single-crystal X-ray diffraction data. Ga4In4B15O33(OH)3 crystallizes in the tetragonal space group I41/a (origin choice 2) with the lattice parameters a = 11.382(2), c = 15.244(2) Å, and V = 1974.9(4) Å3. The structure of the quaternary triel borate consists of a complex network of BO4 tetrahedra, edge-sharing InO6 octahedra in dinuclear units, and very dense edge-sharing GaO6 octahedra in tetranuclear units.

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