scholarly journals Incommensurately Modulated Crystal Structure and Photoluminescence Properties of Eu2O3- and P2O5-Doped Ca2SiO4 Phosphor

Materials ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 58
Author(s):  
Hiromi Nakano ◽  
Shota Ando ◽  
Konatsu Kamimoto ◽  
Yuya Hiramatsu ◽  
Yuichi Michiue ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Light Emission ◽  
Red Light ◽  
Basic Unit ◽  
Β Phase ◽  
Stacking Order ◽  
Cell Dimensions ◽  
Incommensurate Modulation ◽  
Unit Cell Dimensions ◽  
Identical Chemical Composition

We prepared four types of Eu2O3- and P2O5-doped Ca2SiO4 phosphors with different phase compositions but identical chemical composition, the chemical formula of which was (Ca1.950Eu3+0.013☐0.037)(Si0.940P0.060)O4 (☐ denotes vacancies in Ca sites). One of the phosphors was composed exclusively of the incommensurate (IC) phase with superspace group Pnma(0β0)00s and basic unit-cell dimensions of a = 0.68004(2) nm, b = 0.54481(2) nm, and c = 0.93956(3) nm (Z = 4). The crystal structure was made up of four types of β-Ca2SiO4-related layers with an interlayer. The incommensurate modulation with wavelength of 4.110 × b was induced by the long-range stacking order of these layers. When increasing the relative amount of the IC-phase with respect to the coexisting β-phase, the red light emission intensity, under excitation at 394 nm, steadily decreased to reach the minimum, at which the specimen was composed exclusively of the IC-phase. The coordination environments of Eu3+ ion in the crystal structures of β- and IC-phases might be closely related to the photoluminescence intensities of the phosphors.

scholarly journals The crystal and molecular structure of the bis(N,N,N′,N′-tetramethylethanediamine) adduct of I(Br)InInBr2, In2Br3I•2C6H16N2, an indium–indium bonded molecule

1984 ◽  
Vol 62 (3) ◽  
pp. 601-605 ◽  
Author(s):  
Masood A. Khan ◽  
Clovis Peppe ◽  
Dennis G. Tuck
Keyword(s):  
Molecular Structure ◽  
Crystal Structure ◽  
Crystal And Molecular Structure ◽  
Heavy Atom ◽  
Orthorhombic Space Group ◽  
Trigonal Bipyramidal ◽  
Cell Dimensions ◽  
Unit Cell Dimensions ◽  
Heavy Atom Method ◽  
Distorted Trigonal Bipyramidal

The crystal structure of the title compound has been determined by the heavy atom method. The crystals are orthorhombic, space group Pbca, with unit cell dimensions a = 22.795(3) Å, b = 17.518(2) Å, c = 12.396(3) Å, Z = 8; R = 0.0409 for 1527 unique "observed" reflections. The structure is disordered, with each halogen site (X) occupied by 75% Br, 25% I. The molecule consists of two X2(tmen)In units (tmen = N,N,N′,N′-tetramethylethanediamine) with distorted trigonal bipyramidal geometry, joined by an In—In bond 2.775(2) Å in length.

scholarly journals X-ray Crystallographic Study of Ranaconitine

2011 ◽  
Vol 6 (11) ◽  
pp. 1934578X1100601
Author(s):  
Yang Li ◽  
Jun-Hui Zhou ◽  
Gui-Jun Han ◽  
Min-Juan Wang ◽  
Wen-Ji Sun ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Diffraction Analysis ◽  
Critical Role ◽  
X Ray Diffraction ◽  
Monoclinic System ◽  
X Ray ◽  
Crystallographic Study ◽  
Cell Dimensions ◽  
Unit Cell Dimensions

The crystal structure of natural diterpenoid alkaloid ranaconitine isolated from Aconitum sinomontanum Nakai has been determined by single crystal X-ray diffraction analysis. The crystal presents a monoclinic system, space group C2 with Z = 4, unit cell dimensions a = 30.972(19) Å, b = 7.688(5) Å, and c = 19.632(12) Å. Moreover, the intermolecular O–H···O hydrogen bonds and weak π-π interactions play a critical role in expanding the dimensionality.

Clathrathydrate von Tetramethylammoniumhydroxid: Neue Phasen und Kristallstrukturen [1] / Clathrate Hydrates of Tetramethylammonium Hydroxide: New Phases and Crystal Structures [1]

1992 ◽  
Vol 47 (2) ◽  
pp. 263-274 ◽  
Author(s):  
Dietrich Mootz ◽  
Dieter Stäben
Keyword(s):  
Unit Cell ◽  
Tetramethylammonium Hydroxide ◽  
Clathrate Hydrates ◽  
Space Group ◽  
Β Phase ◽  
Metastable Structure ◽  
Cell Dimensions ◽  
Structure Determinations ◽  
Butyl Amine ◽  
Unit Cell Dimensions

The melting diagram of the system tetramethylammonium hydroxide-water has been reinvestigated in the region of 66.67 - 100 mol% H2O , using DTA , DSC and temperature-dependent X-ray powder diffraction. This was done as correction and supplementation of a previous study in the same laboratory (D. Mootz, R. Seidel, J. Incl. Phenom. 8 , 139 (1990)). The system is now considered to contain as many as eight stable hydrates, three of them dimorphic with a low-temperature α and a high-temperature β form. The compositions are Me4NOH · χH2O with χ = 2 (α and β), 4, 4.6 (α and β), 5 (α and β), 6.67, 7.5, 8.75 and 10. A second 7.5-hydrate, called 7 .5 α in the previous study, is now regarded as metastable. - Structure determinations have been performed for the new phases with x = 4.6 (α), 6.67 and 8.75. The 4.6 α-hydrate, transforming to 4.6 β at 32 °C, is cubic with space group Pa3̄ and Z = 40 formula units per unit cell. The lattice constant is a = 21.493 Å at -160 °C. The 6.67-hydrate, melting with decomposition at 13 °C, is monoclinic with space group P21/m and Z = 6 . It was studied as the O-deuterated isotype with unit-cell dimensions a = 11.874, b = 20.019, c = 8.272 Å and β = 103.84° at 3 °C. The 8.75-hydrate, melting with decomposition at - 3 °C, is cubic with space group 14̄3 d, Z = 16 and a = 18.38(2) Å at - 20 °C. The three structures, as most others of the higher hydrates of the system studied previously, are those of polyhedral clathrate hydrates. For the hydrates 4 .6 α and 6.67 deviations of the anionic, i.e. proton-deficient, new water structures from being fully four-connected are described in detail. The 8.75-hydrate is isostructural with the hitherto unparalleled 9.75-hydrate of t-butyl amine. - The phase identity and structure of the 4.6 β-hydrate were recognized as those attributed to an erroneously assumed 5 β-phase in the previous study. 5 β now denotes the room-temperature form of the pentahydrate, previously called 5 α. The present 5 α is another of the new phases and the only one of the system with its structure still undetermined.

scholarly journals The reaction of 3,5-diphenyl-1,2-dithiolium-4-olate with aniline: the crystal structure of 1-phenylimino-2-phenylamino-3-phenylindene

1987 ◽  
Vol 65 (12) ◽  
pp. 2830-2833 ◽  
Author(s):  
David M. McKinnon ◽  
Peter D. Clark ◽  
Robert O. Martin ◽  
Louis T. J. Delbaere ◽  
J. Wilson Quail
Keyword(s):  
Molecular Structure ◽  
Crystal Structure ◽  
Single Crystal ◽  
Least Squares ◽  
Direct Methods ◽  
Monoclinic Space Group ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cell Dimensions ◽  
Unit Cell Dimensions

3,5-Diphenyl-1,2-dithiolium-4-olate (1) reacts with aniline to form 1-phenylimino-2-phenylamino-3-phenylindene (3a). Under suitable conditions, 6-phenylbenzo[b]indeno[1,2-e]-1,2-thiazine is also formed. These structures are confirmed by alternative syntheses. The molecular structure of 3a has been determined by single crystal X-ray diffraction. Compound 3a crystallizes in the monoclinic space group C2/c with unit cell dimensions a = 20.777(3) Å, b = 6.130(3) Å, c = 31.327(3) Å, 3 = 99.59(1)°, and Z = 8. The structure was solved by direct methods and refined by least squares to a final R = 0.055. The molecular structure of 3a shows the three phenyl containing substituents to have the planes of their ring systems tilted between 40° and 60° from the plane of the indene system due to steric repulsions.

Crystal structures of phenacylkojate (2-(hydroxymethyl)-5-phenacyloxy-4H-pyran-4-one) and its complex with sodium chloride: bis(phenacylkojate)sodium chloride

1976 ◽  
Vol 54 (17) ◽  
pp. 2723-2732 ◽  
Author(s):  
Simon E. V. Phillips ◽  
James Trotter
Keyword(s):  
Crystal Structure ◽  
Sodium Chloride ◽  
Potassium Iodide ◽  
Unit Cell ◽  
Monoclinic Space Group ◽  
Hydroxyl Groups ◽  
Space Group ◽  
Cell Dimensions ◽  
Unit Cell Dimensions ◽  
Iodide Complex

The structures of the title compounds have been determined by three dimensional X-ray crystal structure analysis.Crystals of anhydrous phenacylkojate are monoclinic, space group P21/c, with unit cell dimensions a = 9.087(4), b = 11.764(3), c = 12.714(4) Å, β = 116.57(2)°, Z = 4. The structure was solved by direct methods and refined by full-matrix least-squares to R = 0.044 for 1225 independent diffractometer observations. The crystal structure is held together by hydrogen bonding between carbonyl and hydroxyl groups and [Formula: see text] interactions.Crystals of the sodium chloride complex are monoclinic, space group C2/c, with unit cell dimensions a = 11.3714(6), b = 15.796(1), c = 14.487(1) Å, β = 97.241(5)°, Z = 4. The structure was solved by heavy atom and Fourier methods and comparison with the previously determined structure of the potassium iodide complex. It was refined to R = 0.040 for 1670 independent diffractometer observations. The structure closely resembles that of the potassium iodide complex (P21/n), but in C2/c, the alkali metal ion being eight co-ordinate in each. Na+—O distances are in the range 2.558–2.674 Å and the [Formula: see text] hydrogen bonded distance is 3.266 Å.

Refinement of the structure of Mg2As2O7

1970 ◽  
Vol 48 (6) ◽  
pp. 890-894 ◽  
Author(s):  
C. Calvo ◽  
K. Neelakantan
Keyword(s):  
Crystal Structure ◽  
Oxygen Atom ◽  
Least Squares ◽  
Unit Cell ◽  
Full Matrix ◽  
Space Group ◽  
Cell Dimensions ◽  
Central Oxygen ◽  
R Value ◽  
Unit Cell Dimensions

The crystal structure of Mg2As2O7 has been refined by full matrix least squares procedures using 587 observed reflections. The structure of Mg2As2O7 is of the thortveitite type, as reported by Łukaszewicz, with space group C2/m and unit cell dimensions a = 6.567(2) Å, b = 8.524(4) Å, c = 4.739(1) Å, β = 103.8(1)°, and Z = 2. The As—O—As group in the anion appears to be linear but the central oxygen atom undergoes considerable disorder in the plane perpendicular to this group. The AsO bond distances uncorrected for thermal motion are 1.67 Å for the As—O(—As) bond and 1.66 and 1.65 Å for the terminal As—O bonds. The final R value obtained is 0.088.

scholarly journals Synthesis, Crystal Structure, and DFT Calculations of 1,3-Diisobutyl Thiourea

2015 ◽  
Vol 2015 ◽  
pp. 1-5 ◽  
Author(s):  
Ataf A. Altaf ◽  
Adnan Shahzad ◽  
Zarif Gul ◽  
Sher A. Khan ◽  
Amin Badshah ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Dft Calculations ◽  
Single Crystal ◽  
Crystal Packing ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cell Dimensions ◽  
Unit Cell Dimensions ◽  
Model Support

1,3-Diisobutyl thiourea was synthesized and characterized by single crystal X-ray diffraction. It gives a monoclinic (α=γ= 90 andβ  ≠90) structure with the space group P21/c. The unit cell dimensions area= 11.5131 (4) Å,b= 9.2355 (3) Å,c= 11.3093 (5) Å,α= 90°,β= 99.569° (2),γ= 90°,V= 1185.78 (8) Å3, andZ= 4. The crystal packing is stabilized by intermolecular (N–H⋯S) hydrogen bonding in the molecules. The optimized geometry and Mullikan's charges of the said molecule calculated with the help of DFT using B3LYP-6-311G model support the crystal structure.

The Crystal Structure of Indium Monobromide

1950 ◽  
Vol 3 (4) ◽  
pp. 581 ◽  
Author(s):  
NC Stephenson ◽  
DP Mellor
Keyword(s):  
Crystal Structure ◽  
Layer Structure ◽  
Unit Cell ◽  
Space Group ◽  
Cell Dimensions ◽  
Unit Cell Dimensions

The crystal structure of indium monobromide has been determined using powder and complete rotation photographs. The unit cell dimensions are ������������ a= 4.46�0.005 Ǻ������������ b=12.39�0.02 Ǻ ������������ c= 4 73�0.01 Ǻwith four molecules per cell. The space group is D172h:: -Cmcm. The structure is a layer structure isomorphous with that of thallium iodide TlI. Each indium has five bromine atoms arranged about it at the corners of a rectangular pyramid with one In-Br bond of 2.80 Ǻ and four In-Br bonds of 3.29 Ǻ. Indium atoms are similarly arranged about bromine atoms.

SECTION– a computer program for the graphic display of cross sections through a unit cell

1999 ◽  
Vol 32 (2) ◽  
pp. 353-354 ◽  
Author(s):  
Leonard J. Barbour
Keyword(s):  
Crystal Structure ◽  
Computer Program ◽  
Cross Sections ◽  
Unit Cell ◽  
Graphic Display ◽  
Cross Sectional ◽  
Cell Dimensions ◽  
Unit Cell Dimensions ◽  
Microsoft Windows ◽  
Symmetry Operations

SECTIONis a 32-bit Microsoft Windows-based program that displays cross-sectional slices through a packed crystal structure. Unit-cell dimensions as well as the unique atomic positions and symmetry operations are read fromSHELXinstruction files.

Crystal and Molecular Structure of Cycasin, (Z)-β-D-Glucopyranosyloxy-NNO-azoxymethane

1995 ◽  
Vol 48 (5) ◽  
pp. 1059 ◽  
Author(s):  
ME Tate ◽  
IM Delaere ◽  
GP Jones ◽  
ERT Tiekink
Keyword(s):  
Molecular Structure ◽  
Crystal Structure ◽  
Structure Analysis ◽  
Crystal And Molecular Structure ◽  
Crystal Structure Analysis ◽  
Monoclinic Space Group ◽  
Cell Dimensions ◽  
Cycas Revoluta ◽  
Unit Cell Dimensions

Characterization of cycasin , (Z)-β-D-glucopyranosyloxy-NNO-azoxymethane, from Cycas revoluta Thunb . is reported. A crystal structure analysis shows the azoxy substituents adopt a Z configuration. The colourless crystals are monoclinic, space group C2 with unit cell dimensions a 15.409(4), b 4.855(4), c 15.752(4) Ǻ, β 109.87(2)°, Z 4; the structure was refined to final R 0.033, 886 reflections with I ≥ 3.0σ(I) being used.

Sign in / Sign up

Export Citation Format

Share Document