Bulk moduli and high-pressure crystal structures of minium, Pb3O4, determined by X-ray powder diffraction

2003 ◽  
Vol 88 (7) ◽  
pp. 996-1002 ◽  
Author(s):  
Robert E. Dinnebier ◽  
Stefan Carlson ◽  
Michael Hanfland ◽  
Martin Jansen
Keyword(s):  
High Pressure ◽  
Crystal Structures ◽  
Powder Diffraction ◽  
X Ray

Structures of two new high-pressure forms of AlPO4 by X-ray powder diffraction and NMR spectroscopy

2011 ◽  
Vol 67 (1) ◽  
pp. 30-40 ◽  
Author(s):  
Masami Kanzaki ◽  
Xianyu Xue ◽  
Sindy Reibstein ◽  
Eleanor Berryman ◽  
Seonyi Namgung
Keyword(s):  
High Pressure ◽  
Nmr Spectroscopy ◽  
Ab Initio ◽  
Crystal Structures ◽  
Powder Diffraction ◽  
Structure Determination ◽  
Rietveld Method ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
X Ray

The crystal structures of two new high-pressure AlPO4 phases are reported. One phase synthesized at 6 GPa and 1523 K is triclinic (P\bar 1) whilst the other phase synthesized at 7 GPa and 1773 K is monoclinic (P2_1/c). 31P MAS (magic-angle spinning) NMR suggests three tetrahedral P sites with equal abundance in both phases. 27Al 3Q MAS NMR spectra provided evidence for two octahedral sites and one five-coordinated Al site in each phase. The crystal structures were solved using an ab initio structure determination technique from synchrotron powder X-ray diffraction data utilizing the local structural information from NMR, and were further refined by the Rietveld method. Both phases contain doubly bent chains made of six edge-shared Al polyhedra (including five-coordinated Al), which are joined by PO4 tetrahedra. The P\bar{1} phase is isostructural with FeVO4 and AlVO4. The two phases differ in the packing manner of the chains. This study has demonstrated that the combined application of ab initio structure determination via X-ray powder diffraction and solid-state NMR spectroscopy is a powerful approach to the rapid solution of complex inorganic crystal structures.

Distorted chiolite crystal structures of α-Na5M3F14 (M=Cr,Fe,Ga) studied by X-ray powder diffraction

2003 ◽  
Vol 18 (2) ◽  
pp. 128-134 ◽  
Author(s):  
A. Le Bail ◽  
A.-M. Mercier
Keyword(s):  
Crystal Structures ◽  
Powder Diffraction ◽  
Room Temperature ◽  
Rietveld Refinements ◽  
Space Group ◽  
X Ray ◽  
Precise Characterization

The crystal structures of the chiolite-related room temperature phases α-Na5M3F14 (MIII=Cr,Fe,Ga) are determined. For all of them, the space group is P21/n, Z=2; a=10.5096(3) Å, b=7.2253(2) Å, c=7.2713(2) Å, β=90.6753(7)° (M=Cr); a=10.4342(7) Å, b=7.3418(6) Å, c=7.4023(6) Å, β=90.799(5)° (M=Fe), and a=10.4052(1) Å, b=7.2251(1) Å, c=7.2689(1), β=90.6640(4)° (M=Ga). Rietveld refinements produce final RF factors 0.036, 0.033, and 0.035, and RWP factors, 0.125, 0.116, and 0.096, for MIII=Cr, Fe, and Ga, respectively. The MF6 polyhedra in the defective isolated perovskite-like layers deviate very few from perfect octahedra. Subtle octahedra tiltings lead to the symmetry decrease from the P4/mnc space group adopted by the Na5Al3F14 chiolite aristotype to the P21/n space group adopted by the title series. Facile twinning precluded till now the precise characterization of these compounds.

The crystal structures of solvent-free alkali-metal squarates from powder diffraction data

2005 ◽  
Vol 220 (11) ◽  
Author(s):  
Robert E. Dinnebier ◽  
Hanne Nuss ◽  
Martin Jansen
Keyword(s):  
High Resolution ◽  
Alkali Metal ◽  
Crystal Structures ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Room Temperature ◽  
Solvent Free ◽  
Crystallographic Data ◽  
Powder Diffraction Data ◽  
X Ray

AbstractThe crystal structures of solvent-free lithium, sodium, rubidium, and cesium squarates have been determined from high resolution synchrotron and X-ray laboratory powder patterns. Crystallographic data at room temperature of Li

Crystal Structures of Pigment Red 170 and Derivatives, as Determined by X-ray Powder Diffraction

2006 ◽  
Vol 45 (8) ◽  
pp. 1313-1317 ◽  
Author(s):  
Martin U. Schmidt ◽  
Detlef W. M. Hofmann ◽  
Christian Buchsbaum ◽  
Hans Joachim Metz
Keyword(s):  
Crystal Structures ◽  
Powder Diffraction ◽  
X Ray

The BaAl4 Structure and its Derivatives from the R-Zn-Ga Systems

2012 ◽  
Vol 194 ◽  
pp. 5-9 ◽  
Author(s):  
Yuriy Verbovytskyy ◽  
Antonio Pereira Gonçalves
Keyword(s):  
Crystal Structures ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Powder Diffraction Data ◽  
Space Group ◽  
X Ray ◽  
First Time

Seven new ternary RZn1+xGa3-x (R = Ce, Pr, Nd, Sm, Ho and Er) and R5Zn2Ga17 (R = Ce) phases are synthesized for the first time. Their crystal structures are solved on basis of X-ray powder diffraction data. The above mentioned compounds belong to the BaAl4 (space group I4/mmm) and Rb5Hg19 (space group I4/m) structure types. Details of the structure of the Ce5Zn2Ga17 compound and relationship with RZn2-xGa2+x (BaAl4 type) and R3Zn8-xGa3+x (La3Al11 type) are briefly discussed.

Phase transitions in ReO3studied by high-pressure X-ray diffraction

2000 ◽  
Vol 33 (2) ◽  
pp. 279-284 ◽  
Author(s):  
J.-E. Jørgensen ◽  
J. Staun Olsen ◽  
L. Gerward
Keyword(s):  
High Pressure ◽  
Phase Transitions ◽  
Powder Diffraction ◽  
Ambient Pressure ◽  
Rhombohedral Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Oxygen Ions ◽  
Pressure Phase ◽  
Related Phase

ReO3has been studied at pressures up to 52 GPa by X-ray powder diffraction. The previously observed cubicIm3¯ high-pressure phase was shown to transform to a monoclinic MnF3-related phase at about 3 GPa. All patterns recorded above 12 GPa could be indexed on rhombohedral cells. The compressibility was observed to decrease abruptly at 38 GPa. It is therefore proposed that the oxygen ions are hexagonally close packed above this pressure, giving rise to two rhombohedral phases labelled I and II. The zero-pressure bulk moduliBoof the observed phases were determined and the rhombohedral phase II was found to have an extremely large value of 617 (10) GPa. It was found that ReO3transforms back to thePm3¯mphase found at ambient pressure.

Determination of the crystal structure of magnesium perchlorate hydrates by X-ray powder diffraction and the charge-flipping method

2010 ◽  
Vol 66 (6) ◽  
pp. 579-584 ◽  
Author(s):  
Kevin Robertson ◽  
David Bish
Keyword(s):  
Crystal Structures ◽  
Powder Diffraction ◽  
Fundamental Parameter ◽  
Magnesium Perchlorate ◽  
Space Group ◽  
X Ray ◽  
Partial Pressures ◽  
Dehydration Reactions

X-ray powder diffraction (XRD) data were used to solve the crystal structures of phases in the magnesium perchlorate hydrate system, Mg(ClO4)2·nH2O (n = 4, 2). A heating stage and humidity generator interfaced to an environmental cell enabled in-situ XRD analyses of dehydration reactions under controlled temperatures and partial pressures of H2O (P_{{\rm H}_2{\rm O}}). The crystal structures were determined using an ab initio charge-flipping method and were refined using fundamental-parameter Rietveld methods. Dehydration of magnesium perchlorate hexahydrate to tetrahydrate (348 K) results in a decrease in symmetry (space group = C2), where isolated Mg2+ cations are equatorially coordinated by four H2O molecules with two [ClO4]− tetrahedra at the apices. Further dehydration to the dihydrate (423 K) leads to bridging of the isolated packets to form double corner-sharing chains of octahedra and polyhedra (space group = C2/m).

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