Crystal Structure and Thermal Behaviour of Er2(SeO4)3 · 8H2O

2004 ◽  
Vol 59 (9) ◽  
pp. 958-962 ◽  
Author(s):  
Ina Krügermann ◽  
Mathias S. Wickleder
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
Single Crystals ◽  
Thermal Behaviour ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Monoclinic Space Group ◽  
Powder Diffraction Data ◽  
Temperature Dependent ◽  
Selenic Acid

Single crystals of Er2(SeO4)3 ・ 8H2O were obtained by dissolving Er2O3 in selenic acid. The selenate crystallizes in the monoclinic space group C2/c (Z = 4, a = 1372.8(2), b = 687.51(7), c = 1860.2(3) pm, β = 101.85(2)◦, Rall = 0.0518) and contains the Er3+ ions in eightfold coordination of oxygen atoms that belong to two crystallographically different SeO42− ions and to four H2O molecules. According to DTA/TG measurements and temperature dependent powder diffraction data, Er2(SeO4)3 ・8H2O decomposes in several steps yielding finally Er2O3. Er2(SeO4)3 and Er2(SeO3)3 could be identified as intermediates, and for Er2(SeO4)3 a phase transition was detected.

The crystal structure of sarmientite, Fe23+ (AsO4)(SO4)(OH)·5H2O, solved ab initio from laboratory powder diffraction data

2014 ◽  
Vol 78 (2) ◽  
pp. 347-360 ◽  
Author(s):  
F. Colombo ◽  
J. Rius ◽  
O. Vallcorba ◽  
E. V. Pannunzio Miner
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Rietveld Method ◽  
Direct Methods ◽  
Hydroxyl Group ◽  
Monoclinic Space Group ◽  
Powder Diffraction Data ◽  
Patterson Function ◽  
Unit Cell Dimensions

AbstractThe crystal structure of sarmientite, Fe23+ (AsO4)(SO4)(OH)·5H2O, from the type locality (Santa Elena mine, San Juan Province, Argentina), was solved and refined from in-house powder diffraction data (CuKα1,2 radiation). It is monoclinic, space group P21/n, with unit-cell dimensions a = 6.5298(1), b = 18.5228(4), c = 9.6344(3) Å, β = 97.444(2)º, V = 1155.5(5) Å3, and Z = 4. The structure model was derived from cluster-based Patterson-function direct methods and refined by means of the Rietveld method to Rwp = 0.0733 (X2 = 2.20). The structure consists of pairs of octahedral-tetrahedral (Fe−As) chains at (y,z) = (0,0) and (½,½), running along a. There are two symmetry-independent octahedral Fe sites. The Fe1 octahedra share two corners with the neighbouring arsenate groups. Both individual chains are related by a symmetry centre and joined by two symmetry-related Fe2 octahedra. Each Fe2 octahedron shares three corners with double-chain polyhedra (O3, O4 with arsenate groups; the O8 hydroxyl group with the Fe1 octahedron) and one corner (O11) with the monodentate sulfate group. The coordination of the Fe2 octahedron is completed by two H2O molecules (O9 and O10). There is also a complex network of H bonds that connects polyhedra within and among chains. Raman and infrared spectra show that (SO4)2− tetrahedra are strongly distorted.

The Crystal Structure of [Mg2(H2O)6(HCO3)3]+Cl–, Containing a Magnesium-based Hetero-polycation

2008 ◽  
Vol 63 (12) ◽  
pp. 1347-1351 ◽  
Author(s):  
Robert E. Dinnebier ◽  
Martin Jansen
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
High Resolution ◽  
Structural Phase Transition ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Structural Phase ◽  
Close Packing ◽  
Powder Diffraction Data ◽  
Hydrogen Carbonate

The crystal structure of di-magnesium hexahydrate trihydrogencarbonate chloride, [Mg2(H2O)6- (HCO3)3]+Cl−, has been determined from high-resolution laboratory powder diffraction data (lattice parameters at r. t.: a = 8.22215(2), c = 39.5044(2) Å, V = 2312.85(2) Å3, space group R3̄̄c, Z = 6). The crystal structure of [Mg2(H2O)6(HCO3)3]+Cl− is built up of alternating sheets of Cl− anions and complex [Mg2(H2O)6(HCO3)3]+ cations consisting of two Mg(OH2)3O3 octahedra interconnected by three disordered hydrogen carbonate groups. The packing can be described as a cubic close packing of [Mg2(H2O)6(HCO3)3]+ cations with the Cl− anions filling all octahedral voids. In the temperature range from r. t. up to decomposition, which takes place in the range 398 K < T < 413 K, no structural phase transition occurs.

Molecular, crystallographic and algorithmic factors in structure determination from powder diffraction data by simulated annealing

2002 ◽  
Vol 35 (4) ◽  
pp. 443-454 ◽  
Author(s):  
Kenneth Shankland ◽  
Lorraine McBride ◽  
William I. F. David ◽  
Norman Shankland ◽  
Gerald Steele
Keyword(s):  
Crystal Structure ◽  
Simulated Annealing ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Solution Process ◽  
Search Space ◽  
Systematic Investigation ◽  
Monoclinic Space Group ◽  
Powder Diffraction Data ◽  
Structure Solution

The crystal structure of famotidine form B has been solved directly from powder diffraction data by the application of simulated annealing. The molecule crystallizes in the monoclinic space groupP21/cwith refined unit-cell dimensionsa = 17.6547 (4),b= 5.2932 (1),c= 18.2590 (3) Å and β = 123.558 (1)° atT= 130 K. The core of this work is a systematic investigation of the influence of algorithmic, crystallographic and molecular factors on the structure solution process. With an appropriate choice of annealing schedule, molecular description and diffraction data range, the overall number of successes in solving the crystal structure is close to 100%. Other factors, including crystallographic search space restrictions and parameter sampling method, have little effect on the structure solution process. The basic principles elucidated here have been factored into the design of theDASHstructure solution program.

Ab initio determination and Rietveld refinement of the crystal structure of Ni0.50TiO(PO4)

1999 ◽  
Vol 14 (1) ◽  
pp. 10-15 ◽  
Author(s):  
P. Gravereau ◽  
J. P. Chaminade ◽  
B. Manoun ◽  
S. Krimi ◽  
A. El Jazouli
Keyword(s):  
Crystal Structure ◽  
Ab Initio ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Rietveld Method ◽  
Heavy Atom ◽  
Monoclinic Space Group ◽  
Powder Diffraction Data ◽  
X Ray ◽  
Heavy Atom Method

The structure of the oxyphosphate Ni0.50TiO(PO4) has been determined ab initio from conventional X-ray powder diffraction data by the “heavy atom” method. The cell is monoclinic (space group P21/c, Z=4) with a=7.3830(5) Å, b=7.3226(5) Å, c=7.3444(5) Å, and β=120.233(6)°. Refinement of 46 parameters by the Rietveld method, using 645 reflexions, leads to cRwp=0.152, cRp=0.120, and RB=0.043. The structure of Ni0.50TiO(PO4) can be described as a TiOPO4 framework constituted by chains of tilted corner-sharing TiO6 octahedra running parallel to the c axis, crosslinked by phosphate tetrahedra and in which one-half of octahedral cavities created are occupied by Ni atoms. Ti atoms are displaced from the center of octahedra units in alternating long (2.231) and short (1.703 Å) Ti–O bonds along chains.

New Crystal Data for Seven Molybdates MIIUMo4O16 (MII = Mg,Mn,Cd,Ca,Hg,Sr,Pb)

1988 ◽  
Vol 3 (2) ◽  
pp. 106-109 ◽  
Author(s):  
M.R. Lee ◽  
M. Quartern ◽  
S. Jaulmes
Keyword(s):  
Solid State ◽  
Single Crystals ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Solid State Reaction ◽  
Monoclinic Space Group ◽  
Crystal Data ◽  
Powder Diffraction Data ◽  
Unit Cell Parameters ◽  
Cell Parameters

AbstractSeven isotopic molybdates MIIUMo4O16 have been synthesized by solid state reaction with MII = Mg, Mn, Cd, Ca, Hg, Sr, Pb. Single crystals of CaUMo4O16 were obtained. Previously reported as triclinic, this compound is monoclinic, space group P2/n. Unit-cell parameters for the seven compounds are:MgUMo4O16: a = 11.393(2), b = 6.505(1), c = 7.918(2) Å, β = 89.81(3)°, V = 586.8(5) Å3, Z = 2, Dx = 5.12 Mg m−3;MnUMo4O16: a = 11.413(2), b = 6.555(1), c = 8.023(1) Å, β = 89.86(2)°, V = 600.2(4)Å3, Z = 2, Dx = 5.18 Mg m−3;CdUMo4O16: a = 11.427(2), b = 6.607(1), c = 8.144(2) Å3, β = 90.40(2)°, V = 614.8(5)Å3, Z = 2, Dx = 5.37 Mg m−3;CaUMo4O16: a = 11.443(3), b = 6.653(2), c = 8.239(2)Å, β = 90.51(3)°, V = 627.2(6)Å3, Z = 2, Dm = 4.83(5), Dx = 4.88 Mg m−3;HgUMo4O16: a = 11.439(3), b = 6.643(1), c = 8.257(2)Å, β = 90.53(3)°, V = 627.4(6)Å3, Z = 2, Dx = 5.73 Mg m−3;SrUMo4O16: 11.465(3), b = 6.768(2), c = 8.492(2) Å, β = 90.86(3)°, V = 658.8(6)Å3, Z = 2, Dx = 4.88 Mg m−3;PbUMo4O16: a = 11.470(4), b = 6.813(2), c = 8.557(2)Å, β = 90.88(4)°, V = 668.7(8)Å3, Dx = 5.41 Mg m−3;Powder diffraction data for each phase are reported.

Crystal and X-Ray Powder Data for Three Orthovanadates M Th2 (VO4)3 (M = K, Rb, Cs)

1989 ◽  
Vol 4 (3) ◽  
pp. 165-167 ◽  
Author(s):  
A. Elfakir ◽  
J.P. Souron ◽  
M. Quartern
Keyword(s):  
Solid State ◽  
Single Crystals ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Solid State Reaction ◽  
Monoclinic Space Group ◽  
Powder Diffraction Data ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters

AbstractThree isotopic orthovanadates MTh2 (VO4)3 with M = K, Rb, Cs have been syndiesized by solid state reaction. Single crystals of K Th2 (VO4)3 and Rb Th2 (VO4)3 were obtained. These compounds are isotypic with the corresponding orthophosphates: monoclinic, space group C2/c, Z = 4. Unit-cell parameters for die diree compounds were determined. Powder diffraction data for each phase are reported.

scholarly journals Symmetry reduction due to gallium substitution in the garnet Li6.43(2)Ga0.52(3)La2.67(4)Zr2O12

2016 ◽  
Vol 72 (3) ◽  
pp. 287-289 ◽  
Author(s):  
Lars Robben ◽  
Elena Merzlyakova ◽  
Paul Heitjans ◽  
Thorsten M. Gesing
Keyword(s):  
Crystal Structure ◽  
Single Crystals ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Powder Diffraction Data ◽  
Lanthanum Zirconate ◽  
Cubic Symmetry ◽  
X Ray ◽  
Symmetry Space ◽  
Symmetry Space Group

Single-crystal structure refinements on lithium lanthanum zirconate (LLZO; Li7La3Zr2O12) substituted with gallium were successfully carried out in the cubic symmetry space groupI\overline{4}3d. Gallium was found on two lithium sites as well as on the lanthanum position. Due to the structural distortion of the resulting Li6.43(2)Ga0.52(3)La2.67(4)Zr2O12(Ga–LLZO) single crystals, a reduction of the LLZO cubic garnet symmetry fromIa\overline{3}dtoI\overline{4}3dwas necessary, which could hardly be analysed from X-ray powder diffraction data.

Powder diffraction data and Rietveld refinement of Hägg-carbide, χ-Fe5C2

1999 ◽  
Vol 14 (2) ◽  
pp. 130-132 ◽  
Author(s):  
Johannes J. Retief
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Systematic Errors ◽  
Rietveld Analysis ◽  
Monoclinic Space Group ◽  
Powder Diffraction Data ◽  
X Ray Diffraction ◽  
X Ray ◽  
Experimental Values

The structure and powder diffraction data of Hägg-carbide (χ-Fe5C2) have been redetermined and improved by X-ray diffraction. Experimental values of 2θ, corrected for systematic errors, relative peak intensities, lattice spacings, and the Miller indices of 27 observed reflections up to 100° 2θ are reported. The unit cell is monoclinic (space group C2/c, Z=4) with a=11.588 Å, b=4.579 Å, c=5.059 Å, and β=97.75°. The crystal structure has been refined by Rietveld analysis, resulting in Rwp=0.073.

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