Bronzes with a tunnel structure KxP4O8(WO3)2m: The tenth member of the series—KP8W40O136

The crystal structure of KP₈W₄₀O₁₃₆, the tenth member of the series K_xP₄O₈(WO₃)_2m, has been resolved by three-dimensional single-crystal X-ray analysis. The space group is $\text{P2}{}_1\text{c}$ and the cell parameters are a = 19.589(3) Å, b = 7.5362(4) Å, c = 16.970(3) Å and β = 91.864(14)°. The framework is built up from ReO₃-type slabs connected through pyrophosphate groups. The structure is compared to those of the other members of the series: although the ReO₃-type slabs show a different type of tilting of the WO₆ octahedra, the dispersion of WO distances is always higher for the octahedra linked to one or two P₂O₇ groups and decreases in proportion as W is farther from these groups. The perovskite cages of the slabs are described and compared to those encountered in the structures of WO₃ and of the bronzes A_xWO₃.     

Structure cristalline du phosphatoantimonate K3Sb3P2O14

K₃Sb₃P₂O₁₄ crystallizes in the rhombohedral system, space group $\text{R}\text{3}\text{m}$ with a = 7.147(1) Å, c = 30.936(6) Å, Z = 3. The structure was determined from 701 reflections collected on a Nonius CAD4 automatic diffractometer with $\text{Mo}\text{K}\text{α}$ radiation. The final R index and the weighted R_w index are 0.033 and 0.042, respectively. The structure is built up from layers of SbO₆ octahedra and PO₄ tetrahedra sharing corners. The potassium ions are situated between the (Sb₃P₂O₁₄)^3? covalent layers.     

KxP2W2O16: A bronze with a tunnel structure built up from PO4 tetrahedra and WO6 octahedra

The structure of a $\text{K}{}_{\mathrm{x}}\text{P}{}_2\text{W}{}_4\text{O}{}_{16}\text{(x ? 0.4)}$ crystal was established by X-ray analysis. The solution in the cell of symmetry $\text{P2}{}_1\text{m}$, with a = 6.6702(5), b = 5.3228(8), c = 8.9091(8) Å, β = 100.546(7)°, Z = 1, has led to R = 0.033 and R_w = 0.036 for 2155 reflections with $\text{σ(I)}\text{I}\text{≤ 0.333}$. This structure can be described as two octahedra-wide ReO₃-type slabs connected through “planes” of PO₄ tetrahedra. A new structural family K_xP₂W_2nO_6n+4 can be foreseen which is closely related to the orthorhombic P₄W₈O₃₂ and the monoclinic Rb_xP₈W_8nO_24n+16 series.     

Crystal growth and X-ray data of the lead phosphates Pb4P2O9 and Pb8P2O13

Single crystals of the title compounds have been grown by the Czochralski technique. Pb₄P₂O₉ crystallizes in the space group $\text{P2}{}_1\text{c}$ with the parameters a = 9.4812 Å, b = 7.1303 Å, c = 14.390 Å, β = 104.51° and Pb₈P₂O₁₃ in $\text{C2}\text{m}$ with a = 10.641 Å, b = 10.206Å c = 14.342 Å, β = 98.34°.     

The crystal structure of a complex cerium(III) molybdate; Ce6(MoO4)8(Mo2O7)

Ce₆Mo₁₀O₃₉ crystallizes in the triclinic system with unit-cell dimensions (from single-crystal data) a = 10.148(5), Å, b = 18.764(6), Å, c = 9.566(5), Å, α = 103.12(7)°, β = 78.07(7)°, γ = 107.69(7)°, and space group $\text{P}\text{1}\text{, z = 2}$. The structure was solved using direct methods with 3113 countermeasured reflections (MoKα radiation), and refined using Fourier and least-squares techniques to a conventional R of 0.039 (ωR = 0.047). Ce₆Mo₁₀O₃₉ has a structure that consists of isolated MoO₄ tetrahedra together with one corner-shared pair of tetrahedra, linked to irregular eight-coordinate Ce(III) polyhedra. The average MoO distance of 1.77 Å, and average CeO distance of 2.52 Å are in good agreement with previously reported values.     

Structure cristalline du tétramétaphosphate de nickel-ammonium heptahydraté: Ni(NH4)2P4O12 · 7H2O

Nickel-ammonium tetrametaphosphate, Ni(NH₄)₂P₄O₁₂ · 7H₂O is triclinic with a = 13.841(3); b = 9.621(5); c = 7.482(2)Å; α = 98.05(4); β = 97.25(4); γ = 103.01(4)°; M = 536.59; V = 947.9ų; Z = 2; D_x = 1.879 g cm^?3; μ = 14.524 cm^?1, and space group $\text{P}\text{1}$. The crystal structure was solved using 1661 independent reflections measured on a single-crystal diffractometer (MoKα). The final R value is 0.056. The two crystallographic independent nickel atoms Ni(1) and Ni(2) are octahedrally coordinated: Ni(1) by four oxygen atoms and two water molecules, Ni(2) by six water molecules. Ni(1), closely connected to two P₄O₁₂ rings, forms a complex anion [Ni(P₄O₁₂)₂(H₂O)₂]^6? which is associated to ammonium polyhedra and [Ni(H₂O)₆]²⁺ octahedra. Another interesting feature of this atomic arrangement is the presence of a large channel (10 × 4) Ų parallel to the $\text{c}$ axis. The internal surface of this channel is covered by six zeolitic water molecules.     

Crystal structure of Fe2P2O7

Fe₂P₂O₇ crystallizes in the $\text{C}\text{1}$ space group with lattice parameters a = 6.649(2)Å, b = 8.484(2)Å, c = 4.488(1)Å, α = 90.04°, β = 103.89(3)°, γ = 92.82(3)°, and ?_cal = 3.86 g/cc. It is essentially isostructural with β-Zn₂P₂O₇. As in the Zn compound, the bridging oxygen atom in the P₂O₇ group shows a high anisotropic thermal motion. It appears that the P-O-P bond angle is linear as a result of extensive π bonding with the p orbitals on the bridging oxygen atom. The high thermal motion is vibration of the atom into cavities in the structure.     

(NH4)4P4O12 · 2Te(OH)6 · 2H2O,the first example of a tetrametaphosphate-tellurate

Ammonium tetrametaphosphate-tellurate dihydrate, (NH₄)₄P₄O₁₂ · 2Te(OH)₆ · 2H₂O, is triclinic with the following unit cell dimensions: a = 11.845(6), b = 8.554(5), c = 7.433(5) Å, α = 66.28(5), β = 95.91(5), γ = 76.00(5)° space group: $\text{P}\text{1}$ and Z = 1. The crystal structure has been determined with a final R value of 0.021. As in the previously described phosphate-tellurates, monophosphate-tellurate and trimetaphosphate-tellurates, the phosphoric anion (here the P₄O₁₂ ring) is independent of the octahedral Te(OH)₆ group. A complete pattern of the hydrogen bonds is given.     

Crystal structures of some niobium and tantalum oxides. VII. K4+5xTa16−xO42 (x ≈ 0.3)

K_4+5xTa_16?xO₄₂ crystallizes in the hexagonal system with unit-cell dimensions (from single-crystal data) a = 9.085(6), c = 12.254(8) Å and space group $\text{P6}{}_3\text{mcm}\text{, Z = 1}$. The structure was solved by Patterson and Fourier techniques and refinement by full-matrix least-squares methods using 271 reflections, measured by counter techniques, with I ? 3.5 σ (I), resulted in an R of 0.060 (R_w = 0.051). The structure consists of units of six octahedra, edge- and corner-shared to one another, that are linked by corner sharing through a single octahedron. This structure provided the “key” to other structures in the K₂O:Ta₂O₅ and Rb₂O:Nb₂O₅ systems. Its significance in this respect is discussed.     

Polyèdre de coordination de l'etain(II) dans SnC2O4: Relations structurales entre SnC2O4, Na2C2O4 et Na2Sn(C2O4)2

The crystal structure of SnC₂O₄ has been determined by X-ray single-crystal techniques and refined to R = 0,018 for 1139 reflections. The cell is monoclinic, space group $\text{C2}\text{c}$ with Z = 4 formula units, the parameters being a = 10,375(3)Å. b = 5,504(2)Å, c = 8,234(3)Å, β = 125,11(2)°. The oxalato groups, located on symmetry centers, are chelated to two Sn atoms through one oxygen on each carbon atom, giving rise to an infinite string (SnC₂O₄)_n. The Sn(II) atom is one-side bonded to four oxygen atoms with two SnO bonds of 2,232(2) Å and two of 2,393(2) Å. The tin atom is in a distorted trigonal bipyramid SnO₄E, the lone pair E occupying one of the apices of the equatorial trigonal base of the polyhedron. Crystal structure comparison with disodium bisoxalatostannate(II), Na₂Sn(C₂O₄)₂, permits one to deduce SnC₂O₄ by crystallographic shear operation $\text{1}\text{8}\text{[34}\text{2}\text{](001)}$ of $\text{c}\text{2}$ periodicity. Na₂Sn(C₂O₄)₂ can be described as an intergrowth of SnC₂O₄ and Na₂C₂O₄ structures and consldered as the first member of a new series Na₂Sn_1+n(C₂O₄)_2+n with n integer ? 0.     

Crystal structure of a barium-zinc decametaphosphate Ba2Zn3P10O30

Barium-zinc decametaphosphate, Ba₂Zn₃P₁₀O₃₀, is monoclinic, $\text{P2}\text{n}$, with the unit cell parameters a = 21.738(15), b = 5.356(5), c = 10.748(8) Å, β = 99.65(3)° and Z = 2. The crystal structure was solved with a final R value of 0.041. This salt provides the first structural evidence for the existence of a 10-phosphorus ring anion.     

Structural changes resulting from doping Ti2O3 with Sc2O3 or Al2O3

The crystal structures of (Ti_1?xSc_x)₂O₃, x = 0.0038, 0.0109, and 0.0413, and of (Ti_0.99Al_0.01)₂O₃, have been determined from X-ray diffraction data collected from single crystals using an automated diffractometer, and have been refined to weighted residuals of 25–34. Cell constants have also been determined for x = 0.0005, 0.0019, and 0.0232. The compounds are rhombohedral, space group $\text{R}\text{3}\text{c}$, and are isomorphous with α-Al₂O₃. The hexagonal cell dimensions range from a = 5.1573(2)Å, c = 13.613(1)Å for (Ti_0.9995Sc_0.0005)₂O₃ to a = 5.1659(4)Å, c = 13.644(1)Å for (Ti_0.9587Sc_0.0413)₂O₃, and a = 5.1526(2)Å, c = 13.609(1)Å for (Ti_0.99Al_0.01)₂O₃. Sc and Al substitution cause similar increases in the short near-neighbor metal-metal distance across the shared octahedral face; for Sc doping the increase is from 2.578(1) Å in pure Ti₂O₃ to 2.597(1) Å in (Ti_0.9587Sc_0.0413)₂O₃. By contrast, changes in the metal-metal distance across the shared octahedral edge appear to be governed by ionic size effects. The distance increases from 2.994(1) Å in Ti₂O₃ to 3.000(1) Å in (Ti_0.9587Sc_0.0413)₂O₃ and decreases to 2.991(1) Å in (Ti_0.99Al_0.01)₂O₃.     

The crystal structure of a complex cerium(III) molybdate containing a dimolybdate chain,Ce2(MoO4)2(Mo2O7)

Ce₂(MoO₄)₂(Mo₂O₇) crystallizes in the triclinic system with unit cell dimensions (from single-crystal data) a = 11.903(8), b = 7.509(5), c = 7.385(5) Å, α = 94.33(8), β = 97.41(8), γ = 88.56(7)°, and space group $\text{P}\text{1}\text{, z = 2}$. The structure was solved using Patterson (“P1 method”) and Fourier techniques. Of the 8065 unique reflections measured by counter techniques, 6314 with I ≥ 3σ(I) were used in the least-squares refinement of the model to a conventional R of 0.035 (R_w = 0.034). The structure of Ce₂(MoO₄)₂(Mo₂O₇) consists of dimolybdate chains of the K₂Mo₂O₇ and (NH₄)₂Mo₂O₇ type separated by isolated MoO₄ tetrahedra and cerium(III) polyhedra.     

The crystal structure of the 2:5 phase in the K2OZrO2 system: K4Zr5O12, a compound with octahedral and trigonal prismatic zirconium(IV) coordination

K₄Zr₅O₁₂ crystallizes in the trigonal system with unit-cell dimensions a = 5.821(2) Å, c = 10.437(3) Å, and space group $\text{P}\text{3}\text{m1}$. The structure was solved by Patterson and Fourier techniques. the 386 unique reflections measured by counter techniques were reduced to 334 with I ? 3σ (I); these were used in full-matrix least-squares refinement of the model to a conventional R of 0.0196 (ωR = 0.0228). K₄Zr₅O₁₂ has a structure that may be described as consisting of perovskite-like layers (potassium ions are cube octahedrally coordinated) with sheets of hexagonal rings of edge-shared trigonal prismatically coordinated zirconium(IV) ions inserted between every third and fourth layer of the perovskite-like structure. The trigonal prisms are face shared to octahedra above and below alternately to form cavities that are occupied by pairs of potassium ions in ninefold coordination.     

A pentagonal tunnel structure with copper in square planar coordination: The oxides KCuNb3O9 and KCuTa3O9

The structure of two new oxides KCuTa₃O₉ and KCuNb₃O₉ has been solved from X-ray powder data and by electron microscopy. Both compounds are orthorhombic, space group Pnc2 with $\text{a ? 8.8}$ Å, $\text{b ? 10.1}$ Å, and $\text{c ? 7.6}$ Å. Their host lattice is built up from corner-sharing MO₆ octahedra (M = Nb, Ta) forming pentagonal tunnels where the K⁺ ions are located. The copper ions are located in distorted perovskite CaCu₃Mn₄O₁₂-type cages and exhibit a square planar coordination. The relationships between these oxides and the TTB, HTB, ITB, and Ba_0.15WO₃ structures are discussed.     

Crystal growth and properties of lead pyrophosphate,Pb2P2O7

Single crystals of Pb₂P₂O₇ have been grown by the Czochralski technique. They have the triclinic space group $\text{P}\text{1}$ with cell dimensions a = 6.9627 Å, b = 6.9754Å, c = 12.764 Å, α = 96.78°, β = 91.16°, γ = 89.68°. There are four molecules per unit cell. Dielectric properties for this compound have been measured and are discussed.     

Crystal structure of KSbP2O8

KSbP₂O₈ crystallizes in the rhombohedral system, space group $\text{R}\text{3}$, with a = 4.7623(4) Å, c = 25.409(4)Å, and Z = 3. The structure was determined from 487 reflexions collected on a NONIUS CAD4 automatic diffractometer with MoK^?α radiation. The final R index and weighted R_w index are 0.030 and 0.038, respectively. This structure is built up from layers of SbO₆ octahedra and PO₄ tetrahedra sharing corners. These (SbP₂O^?₈)_n layers are very similar to the (ZrP₂O^2?₈)_n layers in the well-known α-ZrP compound.     

Substitution in barium-fluoride apatite: The crystal structures of Ba10(PO4)6F2, Ba6La2Na2(PO4)6F2 and Ba4Nd3Na3(PO4)6F2

The crystal structures of the apatites Ba₁₀(PO₄)₆F₂(I), Ba₆La₂Na₂(PO₄)₆F₂(II) and Ba₄Nd₃Na₃(PO₄)₆F₂ (III) have been determined by single-crystal X-ray diffraction. All three compounds crystallize in a hexagonal apatite-like structure. The unit cells and space groups are: I, a = 10.153(2), c = 7.733(1)Å, $\text{P6}{}_3\text{m}\text{; a = 9.9392(4), c = 7.4419(5)}$Å, $\text{P}\text{6}$; III, a = 9.786(2), c = 7.281(1)Å, $\text{P}\text{3}$. The structures were refined by normal full-matrix crystallographic least squares techniques. The final values of the refinement indicators R_w and R are: I, R_w = 0.026, R = 0.027, 613 observed reflections; II, R_w = 0.081, R = 0.074, 579 observed reflections; III, R_w = 0.062, R = 0.044, 1262 observed reflections.In I, the Ba(1) atoms located in columns on threefold axes, are coordinated to nine oxygen atoms; the Ba(2) sites form triangles about the F site and are coordinated to six oxygen atoms and one fluoride ion. The fluoride ions are statistically displaced ～0.25 Å from the Ba(2) triangles. This displacement of the F ions is analogous to the displacement of OH ion in Ca₁₀(PO₄)₆(OH)₂.The structures of II and III contain disordered cations. In II there is disorder between La and Na in the column cation sites as well as triangle sites. In III, Nd and Na ions are ordered in the column sites, but there is disorder among Ba and the remaining Nd and Na ions in the triangle sites to give an average site population of $\text{2}\text{3}\text{Ba}\text{,}\text{1}\text{6}\text{Nd}\text{,}\text{1}\text{6}\text{Na}$. The coordination of the rare earth ions and Na ions in the ordered column sites are nine and six oxygens, respectively, in accord with the greater charge of the rare earth ions as compared with Na. The F ions in both II and III suffer from considerable disorder in position, and their locations are not precisely known.     

Structural studies in the Li2MoO4MoO3 system: Part 1 the low temperature form of lithium tetramolybdate,LLi2Mo4O13

LLi₂Mo₄o₁₃ crystallizes in the triclinic system with unit-cell dimensions a = 8.578 Å, b = 11.450 Å, c = 8.225 Å, α = 109.24°, β = 96.04°, γ = 95.95° and space group $\text{P}\text{1}\text{, Z = 3}$. The calculated and measured densities are 4.02 g/cm³ and 4.1 g/cm³ respectively. The structure was solved using three-dimensional Patterson and Fourier techniques. Of the 2468 unique reflections collected by counter methods, 1813 with I ? 3σ(I) were used in the least-squares refinement of the model to a conventional R of 0.031 (ωR = 0.038). LLi₂Mo₄O₁₃ is a derivative of the V₆O₁₃ structure with oxygen ions arranged in a face-centred cubic type array with octahedrally coordinated molybdenum and lithium ions ordered into layers.     

The crystal structure of Cu4(PO4)2O

Cu₄(PO₄)₂O crystallizes in the space group $\text{P}\text{1}$ with a = 7.5393(8) Å, b = 8.1021(9) Å, c = 6.2764(8) Å, α = 113.65(1)°, β = 98.42(1)° and γ = 74.19(1)°. The structure was refined by full-matrix least-squares techniques using automatic diffractometer data to R = 0.046 (R_w = 0.056). Four unique copper atoms are in six, five-, and four-coordinated polyhedra which are linked together to form a three-dimensional network. The structure is best described in terms of a cubic close-packed array of oxygen atoms with one-tenth of the possible anion sites vacant.