Determining the crystal structure of Sr5(PO4)3Br, a new compound in the apatite series, by powder diffraction modeling

1998 ◽  
Vol 13 (2) ◽  
pp. 70-73 ◽  
Author(s):  
Dagmar Nötzold ◽  
Harm Wulff
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Powder Diffraction ◽  
Figure Of Merit ◽  
Rietveld Method ◽  
Structure Model ◽  
Powder Diffraction Data ◽  
X Ray ◽  
Cell Parameters ◽  
Atomic Parameters

Pentastrontium bromidephosphate, Sr5(PO4)3Br, was prepared by solid state reaction. The crystal structure of polycrystalline Sr5(PO4)3Br was refined from X-ray powder diffraction data by the Rietveld method using the structure model of Sr5(PO4)3Cl single crystals. Sr5(PO4)3Br is isostructural with Sr5(PO4)3Cl. The space group is P63/m. The cell parameters are a0=9.9641(1) Å, c0=7.2070(1) Å, α=β=90°, γ=120°, Z=2, d(calc)=4.27 g/cm3, and d(expt)=4.10 g/cm3. Atomic parameters are given. Final values are Rp=10.9%, Rwp=14.3%, and S=1.28. The figure of merit is F30=58 (0.013, 39).

Crystal structures of newly synthesized SbV1.50FeIII0.50(PO4)3 and (SbV0.50FeIII0.50)P2O7

2007 ◽  
Vol 22 (1) ◽  
pp. 47-54 ◽  
Author(s):  
Abderrahim Aatiq ◽  
Rachid Bakri
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Powder Diffraction ◽  
Room Temperature ◽  
Rietveld Method ◽  
Hexagonal Cell ◽  
Space Group ◽  
X Ray ◽  
Cell Parameters ◽  
Air Atmosphere

Synthesis and structure of two phosphates belonging to the ternary Sb2O5-Fe2O3-P2O5 system are reported. Structures of both SbV1.50FeIII0.50(PO4)3 and (SbV0.50FeIIIe0.50)P2O7 phases, obtained by solid state reaction in air atmosphere at 950 °C and 900 °C, respectively, were determined at room temperature from X-ray powder diffraction using the Rietveld method. Sb1.50Fe0.50(PO4)3 phosphate belongs to the Nasicon-type structure with R32 space group. Hexagonal cell parameters are ahex.=8.305(1) Å and chex.=22.035(2) Å. Rietveld refinement results show a 2-2 ordered distribution, along the c-axis, of X(1) and X(2) sites (crystallographic formula [Sb0.88Fe0.12]X(1)[Fe0.38Sb0.62]X(2)(PO4)3) in the Nasicon framework. (Sb0.50Fe0.50)P2O7 is isotypic with β-SbP2O7 pyrophosphate [Pna21 space group; a=7.865(1) Å, b=15.699(2) Å, c=7.847(1) Å]. Its crystal structure is built up from corner-shared SbO6 or FeO6 octahedra and P2O7 groups (two group types). Each P2O7 group shares its six vertices with three SbO6 and three FeO6 octahedra, and each octahedra is connected to six P2O7 groups. A quasi 1-1 ordered distribution, along the b-axis, of Sb5+ and Fe3+ ions in the pyrophosphate framework are observed.

Structure Re-determination of LASSBio-294 – a cardioactive compound of the N-acylhydrazone class – using X-ray powder diffraction data

2013 ◽  
Vol 28 (S2) ◽  
pp. S491-S509 ◽  
Author(s):  
Fanny N. Costa ◽  
Fabio Furlan Ferreira ◽  
Tiago F. da Silva ◽  
Eliezer J. Barreiro ◽  
Lídia M. Lima ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Goodness Of Fit ◽  
Rietveld Method ◽  
Therapeutic Interventions ◽  
Powder Diffraction Data ◽  
X Ray ◽  
Cell Parameters

Many N-acylhydrazone derivatives synthetized in LASSBio® cannot be prepared as single crystals of sufficient size and/or quality for structure determination to be carried out using single crystal X-ray diffraction techniques. This article highlights the opportunity for determining crystal structures of this class of compounds directly from powder diffraction data. For this task, the crystal structure of LASSBio-294 was re-determined by means of conventional X-ray powder diffraction data and so, compared with the crystal structure already determined for single crystal data. LASSBio-294 is a cardioactive compound of the N-acylhydrazone class, which can become part of the therapeutic interventions designed to decrease exertional fatigue, and, consequently, improve the quality of life of patients suffering from chronic heart failure. Its final crystal structure was refined by means of the Rietveld method (Rietveld, 1967; 1969). This drug crystallizes in a monoclinic (P21/c) space group, with unit cell parameters a = 11.3413(3) Å, b = 12.3573(4) Å, c = 9.0158(3) Å, β = 89.821(2)°, V = 1263.55(7) Å3, Z = 4, Ź = 1 and ρcalc = 1.4419(1) g cm−3. The goodness-of-fit indicator and R-factors were, respectively: χ2 = 1.203, RBragg = 0.696%, Rwp = 5.59%, Rexp = 4.65% and Rp = 4.18%. The molecules in LASSBio-294 are H-bonded along the c-axis involving the atoms N(3)–H(8)···O(4).

Crystal structure of the ternary semiconductor Cu2In14/3□4/3Se8 determined by X-ray powder diffraction data

2018 ◽  
Vol 33 (3) ◽  
pp. 237-241 ◽  
Author(s):  
Gerzon E. Delgado ◽  
Luigi Manfredy ◽  
S. A. López-Rivera
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Rietveld Method ◽  
Structural Models ◽  
Powder Diffraction Data ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Ternary Semiconductor

The crystal structure of the partially ordered vacancy compound Cu2In14/3□4/3Se8, belonging to the system I3-III7-□2-VI12, was analyzed using X-ray powder diffraction data. Several structural models were derived from the structure of the selenium-rich phase β-Cu0.39In1.2Se2 by permuting the cations in the available Wyckoff positions. The refinement of the best model by the Rietveld method in the tetragonal space group P$\overline 4 $ 2c (No 112), with unit-cell parameters a = 5.7487(3) Å, c = 11.5106(6) Å, V = 380.40(3) Å3, led to Rp = 9.0%, Rwp = 9.9%, Rexp = 7.2%, S = 1.4 for 134 independent reflections. This model has the following Wyckoff site atomic distribution: Cu in 2e (0,0,0); In in 2b (½,0,¼), 2d (0,½,¼), and 2f (½,½,0);□ in 2f (½,½,0); Se in 8n (x,y,z).

X-ray powder diffraction data of LaNi0.5Ti0.45Co0.05O3, LaNi0.45Co0.05Ti0.5O3, and LaNi0.5Ti0.5O3 perovskites

2021 ◽  
pp. 1-6
Author(s):  
Mariana M. V. M. Souza ◽  
Alex Maza ◽  
Pablo V. Tuza
Keyword(s):  
Crystal Structure ◽  
Rietveld Method ◽  
Pechini Method ◽  
Powder Diffraction Data ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Modified Pechini Method ◽  
Scanning Electron

In the present work, LaNi0.5Ti0.45Co0.05O3, LaNi0.45Co0.05Ti0.5O3, and LaNi0.5Ti0.5O3 perovskites were synthesized by the modified Pechini method. These materials were characterized using X-ray fluorescence, scanning electron microscopy, and powder X-ray diffraction coupled to the Rietveld method. The crystal structure of these materials is orthorhombic, with space group Pbnm (No 62). The unit-cell parameters are a = 5.535(5) Å, b = 5.527(3) Å, c = 7.819(7) Å, V = 239.2(3) Å3, for the LaNi0.5Ti0.45Co0.05O3, a = 5.538(6) Å, b = 5.528(4) Å, c = 7.825(10) Å, V = 239.5(4) Å3, for the LaNi0.45Co0.05Ti0.5O3, and a = 5.540(2) Å, b = 5.5334(15) Å, c = 7.834(3) Å, V = 240.2(1) Å3, for the LaNi0.5Ti0.5O3.

Crystallographic study of ternary ordered skutterudite IrGe1.5Se1.5

2010 ◽  
Vol 25 (3) ◽  
pp. 247-252 ◽  
Author(s):  
F. Laufek ◽  
J. Návrátil
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Rietveld Method ◽  
Crystallographic Data ◽  
Powder Diffraction Data ◽  
X Ray ◽  
Crystallographic Study ◽  
Related Phase ◽  
The Ideal

The crystal structure of skutterudite-related phase IrGe1.5Se1.5 has been refined by the Rietveld method from laboratory X-ray powder diffraction data. Refined crystallographic data for IrGe1.5Se1.5 are a=12.0890(2) Å, c=14.8796(3) Å, V=1883.23(6) Å3, space group R3 (No. 148), Z=24, and Dc=8.87 g/cm3. Its crystal structure can be derived from the ideal skutterudite structure (CoAs3), where Se and Ge atoms are ordered in layers perpendicular to the [111] direction of the original skutterudite cell. Weak distortions of the anion and cation sublattices were also observed.

Crystal structure of potassium tetraperoxomolybdate (VI) K2[Mo(O2)4]

2005 ◽  
Vol 20 (3) ◽  
pp. 203-206 ◽  
Author(s):  
M. Grzywa ◽  
M. Różycka ◽  
W. Łasocha
Keyword(s):  
Crystal Structure ◽  
Low Temperature ◽  
Diffraction Pattern ◽  
Powder Diffraction ◽  
Rietveld Method ◽  
Structure Refinement ◽  
Crystal Structure Refinement ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters

Potassium tetraperoxomolybdate (VI) K2[Mo(O2)4] was prepared, and its X-ray powder diffraction pattern was recorded at low temperature (258 K). The unit cell parameters were refined to a=10.7891(2) Å, α=64.925(3)°, space group R−3c (167), Z=6. The compound is isostructural with potassium tetraperoxotungstate (VI) K2[W(O2)4] (Stomberg, 1988). The sample of K2[Mo(O2)4] was characterized by analytical investigations, and the results of crystal structure refinement by Rietveld method are presented; final RP and RWP are 9.79% and 12.37%, respectively.

scholarly journals Preparation, differential thermal analysis and crystal structure of the new quaternary compound CuVInSe3

2018 ◽  
Vol 64 (6) ◽  
pp. 548
Author(s):  
Gustavo Marroquin ◽  
Gerzon E. Delgado ◽  
Pedro Grima-Gallardo ◽  
Miguel Quintero
Keyword(s):  
Crystal Structure ◽  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Powder Diffraction ◽  
Powder Diffraction Data ◽  
Unit Cell Parameters ◽  
Quaternary Compound ◽  
X Ray ◽  
Cell Parameters ◽  
Structural Variables

The crystal structure of the quaternary compound CuVInSe3 belonging to the system (CuInSe2)1-x(VSe)x with x= ½, was analyzed using X-ray powder diffraction data. This material was synthesized by the melt and anneal method and crystallizes in the tetragonal space group P2c (Nº 112), with unit cell parameters a = 5.7909(4) Å, c = 11.625(1) Å, V = 389.84(5) Å3. The Rietveld refinement of 25 instrumental and structural variables led to Rexp = 6.6 %, Rp = 8.7 %, Rwp = 8.8 % and S = 1.3 for 4501 step intensities and 153 independent reflections. This compound has a normal adamantane structure and is isostructural with CuFeInSe3. The DTA indicates that this compound melts at 1332 K.

Powder diffraction data of two tricydic diazonia diiodide salts used in silver iodide solid electrolytes

1993 ◽  
Vol 8 (3) ◽  
pp. 175-179
Author(s):  
J. Estienne ◽  
O. Cerclier ◽  
J. J. Rosenberg
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Silver Iodide ◽  
Solid Electrolytes ◽  
Rietveld Method ◽  
Powder Diffraction Data ◽  
Organic Salts ◽  
X Ray ◽  
Structure Determinations

Indexed X-ray powder diffraction data are reported for two organic salts with carbon rings having two quaternary nitrogens: diazonia-6,9 dispiro [5.2.5.2] hexadecane and diazonia-6,9 dispiro [5.2.5.3] heptadecane diiodides. For these compounds, which give solid electrolytes when associated with AgI, powder diffraction diagrams calculated by the Rietveld method from single crystal structure determinations are presented and are compared to the experimental diffraction data.

Cristobalite-Related Phases in the NaAlO2–NaAlSiO4 System. II. A Commensurately Modulated Cubic Structure

1998 ◽  
Vol 54 (5) ◽  
pp. 547-557 ◽  
Author(s):  
R. L. Withers ◽  
J. G. Thompson ◽  
A. Melnitchenko ◽  
S. R. Palethorpe
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Rietveld Method ◽  
Powder Diffraction Data ◽  
Tetrahedral Framework ◽  
X Ray ◽  
Sodium Aluminosilicate ◽  
Vacancy Ordering ◽  
Cubic Structure

The crystal structure of a new cubic cristobalite-related sodium aluminosilicate Na1.45Al1.45Si0.55O4 [P213, a = 14.553 (1) Å] has been modelled using a modulation wave approach and the model tested against X-ray powder diffraction data using the Rietveld method. Owing to there being 64 independent positional parameters and eight independent Na sites, refinement of the tetrahedral framework atom positions and Na occupancies was not possible. The framework was modelled successfully in terms of q 1 = 1\over 4〈020〉_p^*-type (p = parent) modulation waves with the requirement that the MO4 (M = Al0.725Si0.275) tetrahedra be as close to regular as possible. Na/vacancy ordering was modelled successfully in terms of q 2 = 1\over 4〈220〉_p^* modulation waves. Only the Na-atom positions were refined. The significance of this unique modulated cubic cristobalite-related structure and the possible insight it provides to understanding β-cristobalite are discussed.

Crystal structure determination of non-stoichiometric Ca4−xRuO6−x (x = 1.17) from X-ray powder diffraction data

2016 ◽  
Vol 31 (1) ◽  
pp. 59-62
Author(s):  
Martin Etter ◽  
Maximilian J. Krautloher ◽  
Nakheon Sung ◽  
Joel Bertinshaw ◽  
Bumjoon Kim ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Flux Growth ◽  
Powder Diffraction Data ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Growth Method ◽  
Calcium Ruthenate

A new non-stoichiometric calcium ruthenate [Ca4−xRuO6−x with x = 1.17(1)] was synthesized by the flux growth method and characterized by the X-ray powder diffraction. The crystal structure is isostructural to the K4CdCl6 type with space group R$\bar 3$c. Unit-cell parameters are a = 9.2881(1), c = 11.1634(2) Å, V = 834.03(3) Å3, and Z = 6.

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