M.T. Averbuch-Pouchot

Crystal structure of triclinic CeP5O14: A new type of ultraphosphate

Abstract The new form of cerium(III) ultraphosphate, CeP 5 O 14 described here is triclinic with a = 9.227(5), b = 8.890(5), c = 7.219(4)A, α = 110.12(5)°, β = 102.68(5)°, γ = 82.13(5)°. Space group is P 1. Z = 2. D x = 3.186 mg/m 3 . Crystal structure of this salt has been solved by using 4587 independent reflections with a final R value 0.029. The atomic arrangement can be described as [P 10 O 28 ] sheets spreading in (110) planes. The internal structure of these sheets is mainly a linkage of (P 12 O 36 ) rings in which 40% of the phosphorus atoms are branching phosphorus.

Crystal chemistry of MIIAg(PO3)3 Polyphosphates for MII = Zn, Co, Ni, Mg and MII4Na4(P4O12)3 Tetrametaphosphates for MII = Zn, Co, Ni: Crystal Structures of ZnAg(PO3)3 and Zn4Na4(P4O12)3

The crystal chemistry of M II M I (PO 3 ) 3 for M I = Na, Ag and M II = Ni, Co, Mg, Zn, Mn is reexamined. All these compounds, previously described as orthorhombic pseudo-cubic s a lts, in fact belong to (at least) two different structural types. A first form corresponds to a cubic (143 d ) tetrametaphosphate M I 4 M II 4 (P 4 O 12 ) 3 ; a second form is an orthorhombic long chain polyphosphate which has a unit cell closely related to the cubic one. We describe the crystal structure of the zinc-sodium salt Na 4 Zn 4 (P 4 O 12 ) 3 which has the cubic form with a = 14.570(A) and Z = 4. The second structure type has been solved with the silver-zinc salt ZnAg(PO 3 ) 3 , with a = 13.921, b = 10.718, c = 9.925(A), and Z = 8; space group Pcca . Final R values are, respectively, 0.045 and 0.024. Chemical preparations and crystal data are given for Ag M II (PO 3 ) 3 with M II = Zn, Co, Ni, Mg and for Na 4 M II 4 (P 4 O 12 ) 3 with M II = Zn, Co, Ni. The close relationship between the atomic arrangement of Zn 4 Na 4 (P 4 O 12 ) 3 and Al 4 (P 4 O 12 ) 3 is discussed. The crystal structure of the long chain polyphosphate corresponds to a new type of infinite (PO 3 ) n chain with a period of 12 tetrahedra.

Crystal chemistry of some addition compounds of alkali iodates with telluric acid

Five addition compounds of telluric acid with alkali iodates are described. Three of these compounds are orthorhombic and isotypic: RbIO 3 ·Te(OH) 6 , KIO 3 ·Te(OH) 6 , and NH 4 IO 3 ·Te(OH) 6 . The crystal structure of this class of compounds has been solved with the potassium salt whose unit-cell dimensions are a = 14.30(1) A, b = 6.734(5) A, c = 8.711(5) A, Pc 2 1 n (C 9 2 v ). Z = 4. Crystal data are given for the two isotypic salts. The crystal structures of two other compounds have been determined. 2KIO 3 ·Te(OH) 6 is trigonal, R 3, with the unit cell dimensions a = 6.500(5) A, c = 25.717(8) A, Z = 3 for the hexagonal description. NH 4 IO 3 ·Te(OH) 6 ·H 2 O is triclinic ( P 1) with a = 10.99(1) A, b = 6.932(4) A, c = 6.559(4) A, α = 88.89(5), β = 90.88(5), γ = 104.48(5)°, and Z = 2. For these three different crystal structure determinations the final R values are, respectively, 0.047, 0.030, and 0.036. The first class of compounds described in this paper, MIO 3 ·Te(OH) 6 ( M = K, Rb, NH 4 ) is a new class of piezoelectric materials.

Crystal structure of cerium(III) diammonium polyphosphate (NH4)2Ce(PO3)5

Abstract Cerium(III) diammonium polyphosphate, (NH 4 ) 2 Ce(PO 3 ) 5 , is triclinic P 1 with the following unit cell dimensions: a = 7.241(5) A, b = 13.314(8) A, c = 7.241(5)A, α = 90.35(5)°, β′ = 107.50(5)°, γ = 90.28(5)°, and Z = 2, V = 665.7 A 3 , D x = 2.85 g/cm 3 . The crystal structure of this new type of polyphosphate has been solved and refined from 4130 independent reflections to a final R value 0.029. The most interesting feature of this salt is the existence of two infinite crystallographically nonequivalent (PO 3 ) − ∞ chains, one running parallel to the a axis, the other along the c axis, both with a period of five tetrahedra. This compound seems to be the first example of a long chain polyphosphate with crystallographic independent chains.

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

Abstract Ammonium tetrametaphosphate-tellurate dihydrate, (NH 4 ) 4 P 4 O 12 · 2Te(OH) 6 · 2H 2 O, is triclinic with the following unit cell dimensions: a = 11.845(6), b = 8.554(5), c = 7.433(5) A, α = 66.28(5), β = 95.91(5), γ = 76.00(5)° space group: P 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 P 4 O 12 ring) is independent of the octahedral Te(OH) 6 group. A complete pattern of the hydrogen bonds is given.

Chemical preparation and X-ray structure determination of K0.30NbF3

Abstract The preparation and crystal structure of K 0.30 NbF 3 single crystals are described. The compound is orthorhombic with a = 7.540(3), b = 13.06(2), c = 7.750(3), A, space group C 222 1 . The structure refines to R = 0.044 with 455 reflections. The framework derives from the Magneli hexagonal tungsten bronze and is similar to the K 0.25 VF 3 orthorhombic phase.

Crystal structure of an ammonium phospho-chromate: (NH4)3PCr4O16

Abstract Ammonium phospho-chromate (NH4)3PCr4O16 is trigonal (R3m) with the following unit cell dimensions: aH = 12.033(8), cH = 10.032(8) A˚, and Z = 3 for the hexagonal cell, aR = 7.710(5) A˚, αR = 102.59(5)° and Z = 1 for the rhombohedral cell. Crystal structure of this compound has been solved with a final R value 0.054. The main feature of this atomic arrangement is the existence in the anion configuration of a central PO4 tetrahedron linked to four CrO4 tetrahedra.

Contribution to the crystal chemistry of tetrametaphosphates(I)

Abstract Crystal structures of K4P4O12 · 2H2O and of two polymorphs of Na2K2P4O12 · 2H2O are reported. K4P4O12 · 2H2O is triclinic P1 with a = 8.153(4), b = 8.222(4), c = 11.154(8) A, α = 97.33(5), β = 95.46(5), γ = 88.92(5)°, and Z = 2. R = 0.021 for 2898 reflections. Na2K2P4O12 · 2H2O has two crystalline forms: a triclinic one ( P 1 ) with a = 11.366(8), b = 7.908(5), c = 7.929(5) A, α = 90.07(5), β = 106.85(5), γ = 95.66(5)°, and Z = 2, and a tetragonal one (P41) with a = 7.928(5), c = 21.66(2), and Z = 4. The crystal structures of the first and second crystalline forms have been solved with final R values of 0.022 for 2505 reflections and 0.036 for 1347 reflections, respectively. Crystal data and chemical preparations are given for Na2(NH4)2P4O12 · 2H2O and Na2Rb2P4O12 · 2H2O, both isotypic with the triclinic form of Na2K2P4O12 · 2H2O. Unit-cell dimensions are, respectively, a = 11.547(8), b = 8.012(5), c = 8.044(5) A, α = 89.76(5), β = 106.22(5), and γ = 94.78(5)°, for the ammonium salt, and a = 11.577(8), b = 8.006(5), c = 8.032(5) A, α = 89.79(5), β = 106.58(5), and γ = 95.19(5)° for the rubidium salt. In addition the crystal structures of the two crystalline forms of Na4P4O12 · 4H2O were reexamined in order to localize the hydrogen atoms and refine their positions.

Crystal structure of Na3PO4 · 12H2O

Abstract The crystal structure of trisodium monophosphate hemihydrate was determined. The space group is C2 c and a unit cell contains eight formula units. The unit cell dimensions of Na 3 PO 4 · 1 2 H 2 O are a = 9.631(3), b = 5.416(2), c = 16.938(8) A, β = 102.60(5)°. The final R value is 0.027 for a set of 1430 independent reflections. This atomic arrangement is mainly a three-dimensional network of distorted NaO6 octahedra. The hydrogen bonding scheme is given.

Crystal structure of K3PCr4O16: A second example of a quaternary phosphorus

Abstract K 3 PCr 4 O 16 is monoclinic ( Cc ) with the following unit cell dimensions: a = 9.512(6), b = 11.74(2), c = 14.74(2) A, β = 106.13(5)°, and Z = 4. The crystal structure has been solved, with a final R value 0.055. The main feature of this atomic arrangement is the geometrical configuration of the PCr 4 O 16 anion: a central PO 4 tetrahedron sharing its four corners with CrO 4 tetrahedra. This phosphochromic anion provides the second example of a quaternary phosphorus in a finite anion.