scholarly journals Crystal structures and X-ray powder diffraction data for Cs2NiSi5O12, RbGaSi2O6, and CsGaSi2O6 synthetic leucite analogues

2021 ◽  
pp. 1-9
Author(s):  
Anthony M. T. Bell ◽  
Alex H. Stone
Keyword(s):  
Alkali Metal ◽  
Powder Diffraction ◽  
Divalent Cation ◽  
Alkali Metal Cation ◽  
Trivalent Cation ◽  
Powder Diffraction Data ◽  
Rietveld Refinements ◽  
X Ray ◽  
Trivalent Cations ◽  
Silicate Framework

Leucites are tetrahedrally coordinated silicate framework structures with some of the silicon framework cations partially replaced by divalent or trivalent cations. These structures have general formulae A2BSi5O12 and ACSi2O6; where A is a monovalent alkali metal cation, B is a divalent cation, and C is a trivalent cation. In this paper, we report the Rietveld refinements of three more synthetic leucite analogues with stoichiometries of Cs2NiSi5O12, RbGaSi2O6, and CsGaSi2O6. Cs2NiSi5O12 is Ia $\bar{3}$ d cubic and is isostructural with Cs2CuSi5O12. RbGaSi2O6 is I41/a tetragonal and is isostructural with KGaSi2O6. CsGaSi2O6 is $I\bar{4}3d$ cubic and is isostructural with RbBSi2O6.

scholarly journals A study of possible extra-framework cation ordering in Pbca leucite structures with stoichiometry RbCsX2+Si5O12 (X = Mg, Ni, Cd)

2019 ◽  
Vol 34 (S1) ◽  
pp. S2-S7
Author(s):  
Anthony M. T. Bell ◽  
C. Michael B. Henderson
Keyword(s):  
Alkali Metal ◽  
Alkali Metal Cation ◽  
Partial Ordering ◽  
Cation Ordering ◽  
Cation Site ◽  
Rietveld Refinements ◽  
Site Disorder ◽  
Trivalent Cations ◽  
Cation Sites ◽  
Silicate Framework

Leucites are silicate framework structures with some of the silicon framework cations partially replaced by divalent or trivalent cations. A monovalent extraframework alkali metal cation is also incorporated to balance the charges. We have previously reported Pbca leucite structures with the stoichiometries Cs2X2+Si5O12 (X = Mg, Mn, Co, Ni, Cu, Zn, Cd) and Rb2X2+Si5O12 (X = Mg, Mn, Ni, Cd). These orthorhombic leucite structures have all the silicon and non-silicon framework cations completely ordered onto separate crystallographic sites. This structure has five distinct Si sites and 1 X site; there are also two distinct sites for the extra-framework Cs or Rb. We have recently synthesised leucite analogues with two different extra-framework cations, these have the stoichiometry RbCsX2+Si5O12 (X = Mg, Ni, Cd). The initial Rietveld refinements assumed 50% Cs and 50% Rb on each of the two extra-framework cation sites. The refined structures for X = Ni and Cd have (within error limits) complete extra-framework cation site disorder. However, for X = Mg there is partial ordering of the extra-framework cation sites, the site occupancies are:- Cs1 0.37(3), Rb1 0.63(3), Cs2 0.63(3), Rb2 0.37(3).

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

scholarly journals Rietveld refinement of the crystal structures of Rb2XSi5O12(X= Ni, Mn)

2016 ◽  
Vol 72 (2) ◽  
pp. 249-252 ◽  
Author(s):  
Anthony M. T. Bell ◽  
C. Michael B. Henderson
Keyword(s):  
High Temperature ◽  
Solid State ◽  
X Rays ◽  
Ordered Structure ◽  
Powder Diffraction Data ◽  
Rietveld Refinements ◽  
Space Group ◽  
X Ray ◽  
Cation Disorder ◽  
Silicate Framework

The synthetic leucite silicate framework mineral analogues Rb2XSi5O12{X= Ni [dirubidium nickel(II) pentasilicate] and Mn [dirubidium manganese(II) pentasilicate]} have been prepared by high-temperature solid-state synthesis. The results of Rietveld refinements, using X-ray powder diffraction data collected using CuKα X-rays, show that the title compounds crystallize in the space groupPbcaand adopt the cation-ordered structure of Cs2CdSi5O12and other leucites. The structures consist of tetrahedral SiO4andXO4units sharing corners to form a partially substituted silicate framework. Extraframework Rb+cations sit in channels in the framework. All atoms occupy the 8cgeneral position for this space group. In these refined structures, silicon andXatoms are ordered onto separate tetrahedrally coordinated sites (T-sites). However, the Ni displacement parameter and the Ni—O bond lengths suggest that for theX= Ni sample, there may actually be some T-site cation disorder.

scholarly journals Rietveld refinement of the low temperature crystal structures of Cs2XSi5O12 (X = Cu, Cd and Zn)

2021 ◽  
Vol 12 (1) ◽  
pp. 60-63
Author(s):  
Anthony Martin Thomas Bell
Keyword(s):  
High Temperature ◽  
Solid State ◽  
Low Temperature ◽  
Rietveld Refinement ◽  
Powder Diffraction ◽  
Low Temperatures ◽  
Powder Diffraction Data ◽  
Space Group ◽  
X Ray ◽  
Silicate Framework

The synthetic leucite silicate framework mineral analogues Cs2XSi5O12 (X = Cu, Cd, Zn) were prepared by high-temperature solid-state synthesis. The results of Rietveld refinement, using 18 keV synchrotron X-ray powder diffraction data collected at low temperatures (8K X = Cu, Zn; 10K X = Cd) show that the title compounds crystallize in the space group Pbca and are isostructural with the ambient temperature structures of these analogues. The structures consist of tetrahedrally coordinated SiO4 and XO4 sharing corners to form a partially substituted silicate framework. Extraframework Cs cations sit in channels in the framework. All atoms occupy the 8c general position for this space group. In these refined structures, silicon and X atoms are ordered onto separate tetrahedrally coordinated sites (T-sites).

Determination of crystal structures and tautomeric states of 2-ammoniobenzenesulfonates by laboratory X-ray powder diffraction

2015 ◽  
Vol 230 (9-10) ◽  
Author(s):  
Sándor L. Bekö ◽  
Christian Czech ◽  
Marcus A. Neumann ◽  
Martin U. Schmidt
Keyword(s):  
Dft Calculations ◽  
Crystal Structures ◽  
Powder Diffraction ◽  
Laboratory Data ◽  
Powder Diffraction Data ◽  
Dft Methods ◽  
Rietveld Refinements ◽  
X Ray ◽  
Polymorph Screening

AbstractThe crystal structures of 4-chloro-5-methyl-2-ammoniobenzenesulfonate and of the corresponding derivatives 4,5-dimethyl- and 4,5-dichloro-2-ammoniobenzenesulfonates have been determined from laboratory X-ray powder diffraction data. The tautomeric state of all three compounds could also be unequivocally determined from laboratory data, using careful Rietveld refinements. The tautomeric state was confirmed by IR spectroscopy. The compounds are neither isostructural to each other nor to the 5-chloro-4-methyl derivate, despite the similar size of the chloro and methyl substituents. The influence of the chloro and methyl substituents on the packing and on the thermal stability is demonstrated. All crystal structures were confirmed by dispersion-corrected DFT calculations. For the 4-chloro-5-methyl and the 4,5-dichloro derivatives the DFT calculations indicated that the observed polymorph should not be the thermodynamical one. However, no other polymorphs could be found in experimental polymorph screening, even using seeding with the corresponding isostructural phases. Obviously the DFT methods need further improvements.

X-ray powder diffraction structural characterization of Pb1 − x Ba x Zr0.65Ti0.35O3 ceramic

2007 ◽  
Vol 63 (5) ◽  
pp. 713-718 ◽  
Author(s):  
M. Mir ◽  
V. R. Mastelaro ◽  
P. P. Neves ◽  
A. C. Doriguetto ◽  
D. Garcia ◽  
...  
Keyword(s):  
Phase Transition ◽  
Powder Diffraction ◽  
Room Temperature ◽  
Ceramic Materials ◽  
Powder Diffraction Data ◽  
Rietveld Refinements ◽  
X Ray ◽  
Cubic Structure ◽  
Good Agreement

The structure of Pb1 − x Ba x Zr0.65Ti0.35O3 (PBZT) ceramic materials with 0.00 ≤ x ≤ 0.40 was studied using synchrotron X-ray powder diffraction data. According to the Rietveld refinements, the structure of PBZT ceramics with x = 0.00, 0.10 and 0.20 at room temperature was rhombohedral R3c. A phase transition from rhombohedral to cubic was observed at 543 and 463 K for x = 0.10 and 0.20, respectively. The refinement for the compositions x = 0.30 and x = 0.40 showed a cubic structure from 10 to 450 K, in good agreement with the dielectric properties of these samples.

Structures of incommensurate and commensurate composite crystals Na x CuO2 (x = 1.58, 1.6, 1.62)

2007 ◽  
Vol 63 (1) ◽  
pp. 17-25 ◽  
Author(s):  
Sander van Smaalen ◽  
Robert Dinnebier ◽  
Mikhail Sofin ◽  
Martin Jansen
Keyword(s):  
Single Crystal ◽  
Powder Diffraction ◽  
Accurate Method ◽  
Structure Model ◽  
Powder Diffraction Data ◽  
X Ray Diffraction ◽  
Rietveld Refinements ◽  
X Ray ◽  
Valence Fluctuations ◽  
Composite Crystals

Na x CuO2 (x ≃ 1.6) has been synthesized for different compositions x, resulting in both commensurate and incommensurate composite crystals. The crystal structures are reported for two incommensurate compounds (x = 1.58 and 1.62) determined by Rietveld refinements against X-ray powder diffraction data. The incommensurate compounds and commensurate Na8Cu5O10 (x = 1.6) are found to possess similar structures, with valence fluctuations of Cu2+/Cu3+ as the origin of the modulations of the CuO2 subsystems; the displacive modulations of Na being defined by the closest Na—O contacts between the subsystems. A comparison of the structure models obtained from single-crystal X-ray diffraction, synchrotron-radiation X-ray powder diffraction and X-ray powder diffraction with Cu Kα1 radiation indicates that single-crystal X-ray diffraction is by far the most accurate method, while powder diffraction with radiation from an X-ray tube provides the least accurate structure model.

Use of TALP with laboratory powder diffraction data from 2D detectors

2013 ◽  
Vol 28 (S2) ◽  
pp. S481-S490
Author(s):  
Oriol Vallcorba ◽  
Anna Crespi ◽  
Jordi Rius ◽  
Carles Miravitlles
Keyword(s):  
Organic Compounds ◽  
Structural Study ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Powder Pattern ◽  
Experimental Setup ◽  
Intensity Data ◽  
Powder Diffraction Data ◽  
X Ray ◽  
Molecular Compounds

The viability of the direct-space strategy TALP (Vallcorba et al., 2012b) to solve crystal structures of molecular compounds from laboratory powder diffraction data is shown. The procedure exploits the accurate metric refined from a ‘Bragg-Brentano’ powder pattern to extract later the intensity data from a second ‘texture-free’ powder pattern with the DAJUST software (Vallcorba et al., 2012a). The experimental setup for collecting this second pattern consists of a circularly collimated X-ray beam and a 2D detector. The sample is placed between two thin Mylar® foils, which reduces or even eliminates preferred orientation. With the combination of the DAJUST and TALP software a preliminary but rigorous structural study of organic compounds can be carried out at the laboratory level. In addition, the time-consuming filling of capillaries with diameters thinner than 0.3mm is avoided.

Crystal structure of the anticancer drug carmustine determined by X-ray powder diffraction

2021 ◽  
pp. 1-3
Author(s):  
Carina Schlesinger ◽  
Edith Alig ◽  
Martin U. Schmidt
Keyword(s):  
Crystal Structure ◽  
Anticancer Drug ◽  
Powder Diffraction ◽  
Room Temperature ◽  
Powder Diffraction Data ◽  
Orthorhombic Space Group ◽  
Commercial Sample ◽  
One Dimensional ◽  
X Ray ◽  
Hydrogen Bond Pattern

The structure of the anticancer drug carmustine (1,3-bis(2-chloroethyl)-1-nitrosourea, C5H9Cl2N3O2) was successfully determined from laboratory X-ray powder diffraction data recorded at 278 K and at 153 K. Carmustine crystallizes in the orthorhombic space group P212121 with Z = 4. The lattice parameters are a = 19.6935(2) Å, b = 9.8338(14) Å, c = 4.63542(6) Å, V = 897.71(2) ų at 153 K, and a = 19.8522(2) Å, b = 9.8843(15) Å, c = 4.69793(6) Å, V = 921.85(2) ų at 278 K. The Rietveld fits are very good, with low R-values and smooth difference curves of calculated and experimental powder data. The molecules form a one-dimensional hydrogen bond pattern. At room temperature, the investigated commercial sample of carmustine was amorphous.

Sign in / Sign up

Export Citation Format

Share Document