Crystal structure of Cd2V2O7

1967 ◽  
Vol 45 (20) ◽  
pp. 2297-2302 ◽  
Author(s):  
P. K. L. Au ◽  
C. Calvo
Keyword(s):  
Crystal Structure ◽  
Oxygen Atom ◽  
Lattice Parameters ◽  
The Other ◽  
Distorted Octahedron ◽  
Thermal Activity ◽  
Space Group ◽  
Bond Angles ◽  
Central Oxygen ◽  
Oxygen Atoms

Cadmium pyrovanadate crystallizes in the C2/m space group with lattice parameters a = 7.088(5) Å, b = 9.091(5) Å, c = 4.963(5) Å, β = 103°21(5)′, and z = 2. This crystal is an isostructure of the mineral thortveitite and thus the anion consists of a pair of centrosymmetrically related corner-sharing VO4 tetrahedra while the cation resides within a distorted octahedron of oxygen atoms. The anion has a linear V—O—V group, but, as with the isostructural pyrophosphates, the central oxygen atom shows an anomalously high thermal activity. The V—O bond distances are 1.76 Å for the inner bond and 1.70 Å for the terminal bond. The bond angles about the anion and cation are similar to those found for the other analogues of thortveitite.

scholarly journals Crystal structure of β-Zn3(PO4)2

1967 ◽  
Vol 45 (20) ◽  
pp. 2303-2316 ◽  
Author(s):  
J. S. Stephens ◽  
C. Calvo
Keyword(s):  
Crystal Structure ◽  
Oxygen Atom ◽  
Lattice Parameters ◽  
Monoclinic Space Group ◽  
Space Group ◽  
Basic Cation ◽  
Cation Coordination ◽  
Oxygen Atoms

β-Zn3(PO4)2 crystallizes in the monoclinic space group P 21/c with lattice parameters, a = 9.393(3) Å, b = 9.170(6) Å, c = 8.686(3) Å, β = 125.73(10)°, and Z = 4. The three independent cations are strongly ligated to 4, 5, and 5 oxygen atoms, with average Zn—O bond distances of 1.98 ± 0.09 Å, 2.10 ± 0.10 Å, and 2.08 ± 0.13 Å respectively. In addition there are two longer Zn—O distances of 2.51 Å and 2.55 Å in this structure. The PO4 groups exist as independent, nearly regular tetrahedra, with each oxygen atom ligated to two cations. Unlike the structures found for the α and γ phases of Zn3(PO4)2, which contain ribbons and sheets respectively as the basic cation coordination motif, the structure of β-Zn3(PO4)2 contains interconnected sheets.

Synthese und Kristallstruktur von (Cu,Zn)3,75Mo3O12 / Synthesis and Crystal Structure of (Cu,Zn)3,75Mo3O12

1995 ◽  
Vol 50 (2) ◽  
pp. 247-251 ◽  
Author(s):  
H. Szillat ◽  
Hk. Müller-Buschbaum
Keyword(s):  
Crystal Structure ◽  
Oxygen Atom ◽  
Single Crystals ◽  
The Other ◽  
Synthesis And Crystal Structure ◽  
Space Group ◽  
Occupancy Factor ◽  
X Ray ◽  
Group D ◽  
Oxygen Atoms

Single crystals of (Cu,Zn)3,75Mo3O12 have been prepared by crystallization from melts and investigated by X-ray diffractometer techniques. (Cu,Zn)3,75Mo3O12 crystallizes orthorhombically, space group D24-P212121, Z = 4, a = 17.947(9), b = 5.092(3), c = 10.685(5) Å. It is isotypic to Cu3,85Mo3O12. All molybdenum atoms are tetrahedrally coordinated by oxygen atoms. There are layers of CuO6 and ZnO6 octahedra, while other metal sites are occupied by copper in a deformed prismatic coordination with one oxygen atom at a remarkably greater distance from copper than the other five. Some of the zinc atoms occupy positions in chains of face-sharing octahedra with an occupancy factor of 0.75. The crystal structure is discussed with respect to the isotypic compound Cu3,85Mo3O12 and compounds of the type CuLnMo2O8.

Refinement of the structure of Mg2As2O7

1970 ◽  
Vol 48 (6) ◽  
pp. 890-894 ◽  
Author(s):  
C. Calvo ◽  
K. Neelakantan
Keyword(s):  
Crystal Structure ◽  
Oxygen Atom ◽  
Least Squares ◽  
Unit Cell ◽  
Full Matrix ◽  
Space Group ◽  
Cell Dimensions ◽  
Central Oxygen ◽  
R Value ◽  
Unit Cell Dimensions

The crystal structure of Mg2As2O7 has been refined by full matrix least squares procedures using 587 observed reflections. The structure of Mg2As2O7 is of the thortveitite type, as reported by Łukaszewicz, with space group C2/m and unit cell dimensions a = 6.567(2) Å, b = 8.524(4) Å, c = 4.739(1) Å, β = 103.8(1)°, and Z = 2. The As—O—As group in the anion appears to be linear but the central oxygen atom undergoes considerable disorder in the plane perpendicular to this group. The AsO bond distances uncorrected for thermal motion are 1.67 Å for the As—O(—As) bond and 1.66 and 1.65 Å for the terminal As—O bonds. The final R value obtained is 0.088.

THE CRYSTAL STRUCTURE AND PHASE TRANSITIONS OF β-Zn2P2O7

1965 ◽  
Vol 43 (5) ◽  
pp. 1147-1153 ◽  
Author(s):  
Crispin Calvo
Keyword(s):  
Crystal Structure ◽  
Phase Transitions ◽  
Oxygen Atom ◽  
Bond Angle ◽  
Thermal Motion ◽  
Mirror Plane ◽  
Red Emission ◽  
Space Group ◽  
Central Oxygen ◽  
Cation Coordination

β-Zn2P2O7 crystallizes in the C2/m space group with lattice parameters a = 6.61 ± 0.01 Å, b = 8.29 ± 0.01 Å, c = 4.51 ± 0.01 Å, β = 105.4° ± 0.2° and z = 2. The anion, P2O7−4, is centered with its mirror plane coinciding with the mirror plane of the space group. The central oxygen atom, however, shows high anisotropic thermal motion and thus it appears that the P—O—P bond angle is linear only as a result of thermal averaging. The cations are found on twofold axes in irregular sixfold coordination and these ZnO6 groups share three edges with neighboring cations. This cation coordination is, therefore, consistent with that predicted from the red emission of β-Zn2P2O7:Mn++.

Organoamido- and Aryloxo-lanthanoids. X. Tris(η2-3,5-di-t-butylpyrazolato)lanthanoid(III) Complexes and the X-Ray Crystal Structure of Er(η2-But2pz)3(thf)2

1994 ◽  
Vol 47 (7) ◽  
pp. 1223 ◽  
Author(s):  
JE Cosgriff ◽  
GB Deacon ◽  
BM Gatehouse ◽  
H Hemling ◽  
H Schumann
Keyword(s):  
Crystal Structure ◽  
Triphenylphosphine Oxide ◽  
The Other ◽  
Monoclinic Space Group ◽  
Space Group ◽  
X Ray ◽  
Trigonal Bipyramidal ◽  
Oxygen Atoms

The complexes Ln (But2pz)3( thf )2 ( Ln = Y, La, Pr, Nd , Sm, Gd, Dy , Er , Yb, Lu; But2pz- = 3,5-di-t-butylpyrazolate; thf = tetrahydrofuran ), and [ Ln (But2pz)3(OPPh3)2].( dme )n ( Ln = La, n = ⅔ ; Ln = Er , n = 1; dme = 1,2-dimethoxyethane) have been prepared by reaction of the lanthanoid metal with bis ( pentafluorophenyl )mercury and the corresponding pyrazole in either thf , or in dme in the presence of triphenylphosphine oxide. The X-ray crystal structure of Er (η2-But2pz)3( thf )2 [monoclinic, space group P21 (No. 4), a 9.738(4), b 19.602(4), c 11.636(4) Ǻ, β 99.42(3)°, R 0.0374 for 3667 observed reflections] shows the complex to be an eight-coordinate monomer with three chelating But2pz ligands . The arrangement of centres ( Cen ) of the N-N bonds of the But2pz ligands [< Er -N> 2.336 Ǻ; Cen-Er-Cen 140.1(4)°, 110.3(4)° and 109.6(4)°] and the thf oxygen atoms [< Er -O> 2.351 Ǻ; O- Er -O 140.1(4)°] is intermediate between trigonal bipyramidal and square pyramidal. The other Ln (But2pz)3( thf )2 complexes and Ln (But2pz)3(OPPh3)2 are considered to have similar structures.

The crystal structure of vlodavetsite, AlCa2(SO4)2F2Cl·4H2O

1995 ◽  
Vol 59 (394) ◽  
pp. 159-162 ◽  
Author(s):  
G. L. Starova ◽  
S. K. Filatov ◽  
G. L. Matusevich ◽  
V. S. Fundamensky
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Coordination Polyhedron ◽  
Specific Interaction ◽  
Distorted Octahedron ◽  
Water Molecules ◽  
Space Group ◽  
Oxygen Atoms

AbsractThe crystal structure of vlodavetsite, AlCa2(SO4)2F2Cl·4H2O, has been determined, space group I4/m, a = 6.870(1), c = 13.342(2) Å, Z = 2, Dx = 2.35 g/cm3. The polyhedron cation chains are parallel to [001] and consist of couples of distorted Ca octahedra alternating with one distorted Al octahedron rotated through 24° with respect to the former. The chains are linked by SO4-tetrahedra so that all of the four tetrahedron oxygen atoms take part in coordination of Ca atoms to form a distorted octahedron with Cl and F atoms. The Al coordination polyhedron consists of two F atoms and four oxygen atoms belonging to water molecules. There is a specific interaction via hydrogen bonds between oxygen atoms of SO4-tetrahedra and water molecules.

scholarly journals Crystal structure of CaK2As2O7 and CdK2P2O7

1976 ◽  
Vol 54 (21) ◽  
pp. 3319-3324 ◽  
Author(s):  
Romolo Faggiani ◽  
Crispin Calvo
Keyword(s):  
Crystal Structure ◽  
Least Squares ◽  
Coordination Sphere ◽  
Divalent Cations ◽  
Lattice Parameters ◽  
Full Matrix ◽  
Space Group ◽  
Bond Lengths ◽  
The Mean ◽  
Oxygen Atoms

Crystals of CaK2As2O7 and CdK2P2O7, both grown from the melt, are monoclinic with Z = 4. The lattice parameters are a = 9.222(6), b = 5.835(3), c = 14.698(10) Å, β = 105.84(5)° with space group P21/c for the diarsenate and a = 9.737(2), b = 5.548(1), c = 12.766(2) Å, β = 106.50(2)° with space group C2/c for the diphosphate. The structures were refined by full-matrix least-squares methods utilizing 2070 reflections (R = 0.056) for the diarsenate and 1145 reflections (R = 0.067) for the diphosphate. Both structures contain pseudo-hexagonally packed anions, in staggered configurations, forming layers with the divalent cations in six coordinate sites between the layers. The average M—O bond lengths are 2.342 and 2.290 Å for M = Ca and Cd respectively. The K ion has nine oxygen atoms with mean K—O bond lengths of 2.943 and 3.020 Å in the diarsenate in the coordination sphere. The mean of the ten shortest K—O is 2.939 Å in the diphosphate.

scholarly journals Struktur und Schwingungsspektrum des α-Undekawolframatophosphats Na2[N(CH3)4]4HPW11O39 · 7H2O / Structure and Vibrational Spectrum of the α-Undecatungstophosphate Na2[N(CH3)4]4HPW11O39 · 7H2O

1981 ◽  
Vol 36 (5) ◽  
pp. 544-550 ◽  
Author(s):  
Joachim Fuchs ◽  
Axel Thiele ◽  
Rosemarie Palm
Keyword(s):  
Crystal Structure ◽  
Vibrational Spectrum ◽  
Lattice Parameters ◽  
X Ray Diffraction ◽  
Vibration Spectra ◽  
Space Group ◽  
X Ray ◽  
Oxygen Atoms

The crystal structure of the compound Na2[N(CH3)4]4HPW11O39 · 7H2O was solved by X-ray diffraction. It crystallizes in the space group C2/m with lattice parameters a= 23.895 Å, b = 11.417 Å, c = 28.930 Å, β= 126.0°.The distances between the tungsten atoms and the kind of bridging by oxygen atoms prove the α-isomer. The differences between the vibration spectra of α-undecatungsto-phosphate and α-dodecatungstophosphate are discussed

Crystal structure of Cu3(AsO4)2

1968 ◽  
Vol 46 (6) ◽  
pp. 917-927 ◽  
Author(s):  
Sandra J. Poulsen ◽  
C. Calvo
Keyword(s):  
Crystal Structure ◽  
Oxygen Atom ◽  
Bond Distance ◽  
Unit Cell ◽  
Monoclinic Crystal ◽  
Space Group ◽  
Bond Lengths ◽  
Oxygen Distance ◽  
Atom Bond ◽  
Oxygen Atoms

Cu3(AsO4)2 forms a monoclinic crystal with lattice parameters a = 6.327(5) Å, b = 8.642(5) Å, c = 11.313(5) Å, β = 92.04(4)°, and Z = 4. The space group is P21/c. The two orthoarsenate anions in the unit cell have average AsO bond lengths of 1.68 Å and 1.70 Å with mean deviations of 0.02 Å and 0.01 Å respectively. The three cations are fivefold coordinated to oxygen atoms with mean cation oxygen atom bond lengths of 2.005 Å, 2.053 Å, and 2.017 Å for the three independent cations. The range of bond distances extends from 1.892 Å to 2.362 Å. Only one additional cation oxygen distance of less than 3 Å occurs and this lies at 2.76 Å. The cation polyhedra form sheets parallel to the ab plane by corner and edge sharing of common oxygen atoms. Adjacent sheets are bonded through the long Cu—O bond distance cited above and by the AsO43− anions. Each of the arsenic atoms shares three oxygen atoms with one sheet and one with the adjacent one.

THE CRYSTAL STRUCTURE OF α-Zn3(PO4)2

1965 ◽  
Vol 43 (2) ◽  
pp. 436-445 ◽  
Author(s):  
Crispin Calvo
Keyword(s):  
Crystal Structure ◽  
Oxygen Atom ◽  
Tetrahedral Site ◽  
Green Emission ◽  
Lattice Parameters ◽  
Monoclinic Space Group ◽  
Space Group ◽  
Oxygen Tetrahedron

α-Zn3(PO4)2 crystallized in the monoclinic space group C2/c with lattice parameters a = 8.14 ± 0.02 Å, b = 5.63 ± 0.01 Å, c = 15.04 ± 0.04 Å, β = 105°08′ ± 05′, and Z = 4. The cations are found in two types of tetrahedrally coordinated sites. One-third of the cations lie on twofold axes within an oxygen tetrahedron. The remaining cations are found in a pair of edge-sharing oxygen atom tetrahedra. The green emission of Mn++ in α-Zn3(PO4)2 is consistent with Mn++ substituting for Zn++ in either tetrahedral site.

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