Crystal structure of calcium zirconium diorthophosphate, CaZr(PO4)2

2003 ◽  
Vol 18 (4) ◽  
pp. 296-300 ◽  
Author(s):  
Koichiro Fukuda ◽  
Kazuko Fukutani
Keyword(s):  
Crystal Structure ◽  
Rietveld Method ◽  
Three Dimensional ◽  
Direct Methods ◽  
Dimensional Structure ◽  
Pentagonal Bipyramid ◽  
Powder Diffraction Data ◽  
Orthorhombic Space Group ◽  
X Ray ◽  
Reliability Indices

The crystal structure of CaZr(PO4)2 was determined from conventional X-ray powder diffraction data using direct methods, and it was further refined by the Rietveld method. The structure was orthorhombic (space group P212121, Z=4) with a=1.448 76(4), b=0.672 13(1), c=0.623 47(2) nm, and V=0.607 10(3) nm3. Final reliability indices were Rwp=6.49%, RB=2.43%, and S=1.32. The Ca atom is sevenfold coordinated, and the Ca atom and surrounding oxygen atoms form a distorted capped octahedron with a mean Ca–O distance of 0.243 nm. The ZrO7 coordination polyhedron is a distorted pentagonal bipyramid with a mean Zr–O distance of 0.216 nm. CaO7, ZrO7, and PO4 polyhedra share edges to form infinite chains with the composition [CaO3ZrO3P2O8]12− along the [010]. Individual chains are linked together, forming a two-dimensional sheet parallel to (100). These sheets are stacked in the [100] direction to form a three-dimensional structure.

Crystal structure of lanthanum oxyorthosilicate, La2SiO5

2006 ◽  
Vol 21 (4) ◽  
pp. 300-303 ◽  
Author(s):  
Koichiro Fukuda ◽  
Tomoyuki Iwata ◽  
Eric Champion
Keyword(s):  
Crystal Structure ◽  
Structural Model ◽  
Rietveld Method ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Monoclinic Space Group ◽  
X Ray ◽  
Reliability Indices ◽  
Volumetric Expansion ◽  
Tricapped Trigonal Prism

The crystal structure of La2SiO5 was refined from laboratory X-ray powder diffraction data (CuKα1) using the Rietveld method. The crystal structure is monoclinic (space group P21∕c,Z=4) with lattice dimensions a=0.93320(2) nm, b=0.75088(1) nm, c=0.70332(1) nm, β=108.679(1)°, and V=0.46687(1) nm3. The final reliability indices were Rwp=7.14%, RP=5.52%, and RB=3.83%. There are two La sites in the structural model, La1 and La2. La1 is ninefold coordinated to oxygen, forming a tricapped trigonal prism with a mean La1-O distance of 0.263 nm. The La2O7 coordination polyhedron is a distorted capped octahedron with a mean La2-O distance of 0.251 nm. The La1O9 polyhedra share faces and the La2O7 polyhedra share edges, forming two sets of sheets that alternate parallel to the (100) plane. These sheets are linked through SiO4 tetrahedra and non-silicon-bonded oxygen atoms to form a three-dimensional structure. This compound is isomorphous with the low-temperature (X1) phases of R2SiO5 (R=Y and Gd). The volumes of RO9 polyhedra steadily increase with increasing ionic radius of R, from Y3+ to Gd3+ to La3+, which causes substantial volumetric expansion of the crystals.

Crystal structure of cyanometallates Me3[Co(CN)6]2 and KMe[Fe(CN)6] with Me=Mn2+, Ni2+, Cu2+

1999 ◽  
Vol 14 (1) ◽  
pp. 25-30 ◽  
Author(s):  
Grzegorz Małecki ◽  
Alicja Ratuszna
Keyword(s):  
Crystal Structure ◽  
Rietveld Method ◽  
Three Dimensional ◽  
Lattice Parameters ◽  
Powder Diffraction Data ◽  
Bridging Ligands ◽  
Cubic Symmetry ◽  
X Ray ◽  
C And N ◽  
Starting Model

The crystal structure of four cyanometallates has been determined from X-ray powder diffraction data using the Rietveld method. The variously hydrated compounds Cu3[Co(CN)6]2, Mn3[Co(CN)6]2 and KNi[Fe(CN)6] crystallize at cubic symmetry (Fm3m) with lattice parameters 10.032(2), 10.413(3) and 10.234(5) Å, respectively. The crystal of KMn[Fe(CN)6]·2H2O shows a monoclinic structure (P21/c) with the lattice parameters a=10.108(2) Å, b=10.104(3) Å, c=10.114(3) Å, β=92°, 93°. The starting model was based on an isomorphic Mn3[Co(CN)6]2 single crystal structure, where Co and Mn ions are octahedrally coordinated by C and N atoms, respectively, forming three-dimensional bimetallic networks with the C≡N groups as bridging ligands.

scholarly journals Crystal structure of barium perchlorate anhydrate, Ba(ClO4)2, from laboratory X-ray powder data

2015 ◽  
Vol 71 (6) ◽  
pp. 588-591 ◽  
Author(s):  
Jeonghoo H. Lee ◽  
Ji Hoon Kang ◽  
Sung-Chul Lim ◽  
Seung-Tae Hong
Keyword(s):  
Crystal Structure ◽  
Three Dimensional ◽  
Structure Type ◽  
Site Symmetry ◽  
Powder Diffraction Data ◽  
Asymmetric Unit ◽  
Orthorhombic Space Group ◽  
Special Position ◽  
X Ray ◽  
Barium Perchlorate

The previously unknown crystal structure of barium perchlorate anhydrate, determined and refined from laboratory X-ray powder diffraction data, represents a new structure type. The title compound was obtained by heating hydrated barium perchlorate [Ba(ClO4)2·xH2O] at 423 Kin vacuofor 6 h. It crystallizes in the orthorhombic space groupFddd. The asymmetric unit contains one Ba (site symmetry 222 on special position 8a), one Cl (site symmetry 2 on special position 16f) and two O sites (on general positions 32h). The structure can be described as a three-dimensional polyhedral network resulting from the corner- and edge-sharing of BaO12polyhedra and ClO4tetrahedra. Each BaO12polyhedron shares corners with eight ClO4tetrahedra, and edges with two ClO4tetrahedra. Each ClO4tetrahedron shares corners with four BaO12polyhedra, and an edge with the other BaO12polyhedron.

Crystal structure of silver metagermanate, Ag2GeO3

2010 ◽  
Vol 25 (1) ◽  
pp. 15-18 ◽  
Author(s):  
Hirokazu Kurachi ◽  
Tomoyuki Iwata ◽  
Shuxin Ouyang ◽  
Jinhua Ye ◽  
Koichiro Fukuda
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Rietveld Method ◽  
Powder Diffraction Data ◽  
X Ray ◽  
Reliability Indices ◽  
Cell Dimensions ◽  
Unit Cell Dimensions ◽  
Identity Period

The crystal structure of Ag2GeO3 was determined from laboratory X-ray powder diffraction data (Cu Kα1) using the Rietveld method. The title compound is orthorhombic with space group P212121, Z=4, unit-cell dimensions a=0.463 09(1) nm, b=0.713 93(2) nm, and c=1.040 79(3) nm, and V=0.344 10(2) nm3 . The final reliability indices were Rwp=5.58%, S=1.26, Rp=4.20%, RB=0.67% , and RF=0.35% . The GeO4 tetrahedra form infinite chains of [Ge2O6] along the a axis, with two tetrahedra per identity period of 0.463 nm. Individual chains are connected by Ag atoms, one-half of which are almost linearly coordinated by two O atoms and the rest are coordinated by three O atoms. The relatively short Ag-Ag distances of 0.299 to 0.339 nm indicate Ag(I)-Ag(I) interaction. This compound is isostructural with Ag2SiO3.

Synthesis, crystal structure, and thermoelectric properties of a new layered carbide (ZrC)3[Al3.56Si0.44]C3

2007 ◽  
Vol 22 (10) ◽  
pp. 2888-2894 ◽  
Author(s):  
Koichiro Fukuda ◽  
Miyuki Hisamura ◽  
Yusuke Kawamoto ◽  
Tomoyuki Iwata
Keyword(s):  
Crystal Structure ◽  
Electrical Conductivity ◽  
Thermoelectric Properties ◽  
Powder Diffraction ◽  
Rietveld Method ◽  
Direct Methods ◽  
Conductivity Measurements ◽  
Maximal Power ◽  
X Ray ◽  
Reliability Indices

A new quaternary layered carbide, (ZrC)3[Al3.56Si0.44]C3, has been synthesized and characterized by x-ray powder diffraction and thermopower and electrical conductivity measurements. The crystal structure was successfully determined using direct methods and further refined by the Rietveld method. The crystal is trigonal (space group R3m*, Z = 3) with lattice dimensions a = 0.331389(7), c = 4.90084(7) nm, and V = 0.46610(1) nm3. The final reliability indices calculated from the Rietveld refinement were Rwp = 9.53% (S = 1.70), Rp = 7.22%, RB = 1.81%, and RF = 0.94%. The crystal structure is composed of the NaCl-type [Zr3C4] slabs separated by the Al4C3-type [Al0.89Si0.11C] layers. This material had thermoelectric properties comparable to the layered carbides (ZrC)2[Al3.56Si0.44]C3 (Zr2[Al3.56Si0.44]C5), (ZrC)2Al3C2, and (ZrC)3Al3C2 in the temperature range of 373–1273 K, with the maximal power-factor value of 6.6 × 10−5 W m−1K−2 at 545 K. The two quaternary carbides have been found to form a homologous series with the general formula of (ZrC)n[Al3.56Si0.44]C3 (n = 2 and 3).

Electron density distribution and crystal structure of lithium barium silicate, Li2BaSiO4

2010 ◽  
Vol 25 (4) ◽  
pp. 336-341 ◽  
Author(s):  
Tatsunari Kudo ◽  
Yoshinori Hirano ◽  
Koichi Momma ◽  
Koichiro Fukuda
Keyword(s):  
Crystal Structure ◽  
Electron Density ◽  
Structural Model ◽  
Rietveld Method ◽  
Three Dimensional ◽  
Direct Methods ◽  
Atomic Displacement ◽  
Entropy Method ◽  
Reliability Indices ◽  
Atomic Displacement Parameters

Crystal structure of Li2BaSiO4 was reinvestigated by laboratory X-ray powder diffraction. The title compound was hexagonal with space group P63cm, Z=6, unit-cell dimensions a=0.810 408(2) nm, c=1.060 829(4) nm, and V=0.603 370(3) nm3. The initial structural model was successfully derived by the direct methods and further refined by the Rietveld method, with the anisotropic atomic displacement parameters being assigned for all atoms. The reliability indices calculated from the Rietveld refinement were Rwp=6.72%, S=1.17, Rp=5.06%, RB=1.86%, and RF=0.98%. The maximum-entropy method-based pattern fitting (MPF) method was used to confirm the validity of the structural model, in which conventional structure bias caused by assuming intensity partitioning was minimized. The final reliability indices calculated from MPF were Rwp=6.74%, S=1.17, Rp=5.10%, RB=1.49%, and RF=0.69%. Atomic arrangements of the final structural model were in excellent agreement with the three-dimensional electron-density distributions determined by MPF.

Electron density distribution and crystal structure of Ca1-x/2AlSi(N3-xOx):Eu2+ (x ∼ 0.11)

2011 ◽  
Vol 26 (S1) ◽  
pp. S38-S43 ◽  
Author(s):  
Daisuke Urushihara ◽  
Toru Asaka ◽  
Takashi Takeda ◽  
Naoto Hirosaki ◽  
Koichiro Fukuda
Keyword(s):  
Crystal Structure ◽  
Electron Density ◽  
Structural Model ◽  
Rietveld Method ◽  
Three Dimensional ◽  
X Ray ◽  
Reliability Indices ◽  
Transmission Electron ◽  
Cell Dimensions ◽  
Unit Cell Dimensions

Crystal structure of Ca1-x/2AlSi(N3-xOx):Eu2+ (x ∼ 0.11) has been characterized using an X-ray powder diffractometer and a transmission electron microscope equipped with an energy dispersive X-ray analyzer (EDX) and an electron energy loss spectrometer (EELS). The title compound is orthorhombic with space group Cmc21, Z = 4, unit-cell dimensions a = 0.979780(7) nm, b = 0.565197(4) nm, c = 0.506356(3) nm, and V = 0.280404(3) nm3. The atom ratio Al:Si was determined to be 1:1 by EDX, and the presence of O atoms in the crystal structure was confirmed by EELS. The x-value and the atomic coordinates of the final structural model were determined by the Rietveld method. The maximum-entropy methods-based pattern fitting (MPF) method was used to confirm the validity of the structural model, in which conventional structure bias caused by assuming intensity partitioning was minimized. The reliability indices calculated from MPF are Rwp = 9.18%, S = 1.17, Rp = 6.77%, RB = 1.91%, and RF = 0.86%. Atomic arrangements of the final structural model are in an excellent agreement with the three dimensional electron-density distributions determined by MPF.

Crystal structure of calcium cobalt orthophosphate, CaCo[Ca0.1Co0.9](PO4)2

2006 ◽  
Vol 21 (3) ◽  
pp. 220-224
Author(s):  
Koichiro Fukuda ◽  
Hajime Hasegawa ◽  
Tomoyuki Iwata ◽  
Shinobu Hashimoto
Keyword(s):  
Crystal Structure ◽  
Rietveld Refinement ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Direct Methods ◽  
Monoclinic Space Group ◽  
Powder Diffraction Data ◽  
Space Group ◽  
X Ray ◽  
Reliability Indices

Crystal structure of Ca1.1Co1.9(PO4)2 was successfully determined from laboratory X-ray powder diffraction data (Co Kα) using direct methods and the Rietveld refinement. The crystal structure was found to be monoclinic (space group P21∕n, Z=4) with lattice dimensions of a=1.452 67(5) nm, b=0.494 34(1) nm, c=0.867 50(3) nm, β=92.316(1)°, and V=0.622 45(3) nm3. The final reliability indices calculated from the Rietveld refinement were Rwp=3.93%, Rp=3.02%, RB=4.10%, and S=1.48. Both Co and Ca atoms were distributed over the 2a and 2d sites with a preference of Ca at the 2d site. The coexistence of Co and Ca on the 2a and 2d sites is indispensable for stabilizing Ca1.1Co1.9(PO4)2 in the Ca3(PO4)2-Co3(PO4)2 system.

X-ray powder diffraction study of LiCrP2O7

2007 ◽  
Vol 63 (3) ◽  
pp. i70-i72 ◽  
Author(s):  
Ludmila S. Ivashkevich ◽  
Kirill A. Selevich ◽  
Anatoly I. Lesnikovich ◽  
Anatoly F. Selevich
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Rietveld Method ◽  
Three Dimensional ◽  
Powder Diffraction Data ◽  
Monoclinic Crystal ◽  
X Ray ◽  
Monoclinic Crystal Structure ◽  
Dimensional Network ◽  
Tetrahedral Environment

The monoclinic crystal structure of lithium chromium(III) diphosphate, LiCrP2O7, isotypic with other members of the series LiM IIIP2O7 (M III = Mn, Fe, V, Mo, Sc and In), was refined from laboratory X-ray powder diffraction data using the Rietveld method. The Cr3+ cation is bonded to six O atoms from five diphosphate anions to form a distorted octahedron. Links between the bent diphosphate anions and the Cr3+ cations result in a three-dimensional network, with tunnels filled by the Li+ cations in a considerably distorted tetrahedral environment of O atoms.

Rietveld refinement of the crystal structure of α-CoSO4

1993 ◽  
Vol 8 (1) ◽  
pp. 54-56 ◽  
Author(s):  
Peter C. Burns ◽  
Frank C. Hawthorne
Keyword(s):  
Crystal Structure ◽  
Rietveld Refinement ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Rietveld Method ◽  
Powder Diffraction Data ◽  
Orthorhombic Space Group ◽  
Space Group ◽  
X Ray

The crystal structure of α-CoSO4 has been refined by the Rietveld method from X-ray powder diffraction data. The structure is orthorhombic, space group Pnma, a = 8.6127(4), b = 6.7058(3), c = 4.7399(2) Å, V = 273.75(3) Å3. Final RB = 2.41%, RP = 5.24%, RWP=6.66%, RWP (expected) =5.74% (WP =weighted profile). The structure consists of edge-sharing octahedral chains parallel to [010] interconnected by SO4 tetrahedra.

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