Rb
 x
 P8W32O112: a tunnel structure built up from ReO3-type blocks and P2O7 groups

Giroult, J. P.; Goreaud, M.; Labbé, Ph.; Raveau, B.

doi:10.1107/s0567740880009466

Cited by 34 publications

(7 citation statements)

References 9 publications

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“…A new oxide with the composition Rb 0.8 P 4 W 16 O 56 (Giroult et al, 1980) was thus isolated. It was the ®rst`diphosphate tungsten bronze', the of®cial name given by Kihlborg (1982), a valuable replacement for previous nomenclature which included tungsten pyrophosphates or tungstophosphates.…”

Section: Introductionmentioning

confidence: 99%

Phosphate tungsten bronze series: crystallographic and structural properties of low-dimensional conductors

Roussel

Pérez

Labbé

2001

Acta Crystallogr B Struct Sci

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Phosphate tungsten bronzes have been shown to be conductors of low dimensionality. A review of the crystallographic and structural properties of this huge series of compounds is given here, corresponding to the present knowledge of the different X-ray studies and electron microscopy investigations. Three main families are described, monophosphate tungsten bronzes, A x (PO 2 ) 4 (WO 3 ) 2m , either with pentagonal tunnels (MPTBp) or with hexagonal tunnels (MPTBh), and diphosphate tungsten bronzes, A x (P 2 O 4 ) 2 (WO 3 ) 2m , mainly with hexagonal tunnels (DPTBh). The general aspect of these crystal structures may be described as a building of polyhedra sharing oxygen corners made of regular stacking of WO 3 -type slabs with a thickness function of m, joined by slices of tetrahedral PO 4 phosphate or P 2 O 7 diphosphate groups. The relations of the different slabs with respect to the basic perovskite structure are mentioned. The structural description is focused on the tilt phenomenon of the WO 6 octahedra inside a slab of WO 3 -type. In this respect, a comparison with the different phases of the WO 3 crystal structures is established. The various modes of tilting and the different possible connections between two adjacent WO 3 -type slabs involve a great variety of structures with different symmetries, as well as the existence of numerous twins in MPTBp's. Several phase transitions, with the appearance of diffuse scattering and modulation phenomena, were analysed by Xray scattering measurements and through the temperature dependence of various physical properties for the MPTBp's. The role of the W displacements within the WO 3 -type slabs, in two modulated structures (m = 4 and m = 10), already solved, is discussed. Finally, the complexity of the structural aspects of DPTBh's is explained on the basis of the average structures which are the only ones solved.

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Section: Introductionmentioning

confidence: 99%

Phosphate tungsten bronze series: crystallographic and structural properties of low-dimensional conductors

Roussel

Pérez

Labbé

2001

Acta Crystallogr B Struct Sci

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“…A 4 + 2 coordination appears for the W(1) atoms with a displacement of 0.22 (2)A, and for the W(3) atoms in spite of a weak displacement of 0.03 (2)A [or 0.10 (2)A for the second sort of W(3)] from the centre of gravity. This group does not appear to be geometrically different from those observed in the integral members (Giroult et al, 1980. Thus, the WO6 octahedra of the PaW28O100 framework are more distorted than those of the members n = 3 and n = 4.…”

Section: Description Of the Structure And Discussionmentioning

confidence: 68%

“…A study of the maps of electron density of Rb and P showed that the occupation of the corresponding sites is only partial, about 40% for Rb and 50% for P, as in RbxP8W32Oll 2 (Giroult et al, 1980). The atoms O(2), 0(4), 0(6), O(12) and O(13) are distributed over two neighbouring positions with an occupancy factor of 0.5 while the electron density contours appear to be almost spherical for the other atoms.…”

Section: Determination Of the Mean Structurementioning

confidence: 99%

Bronzes with a tunnel structure RbxP8W8nO24n+16. III. RbxP8W28O100: a member corresponding to a non-integral n value n = 3.5

Giroult¹,

Goreaud²,

Labbé³

et al. 1982

Acta Crystallogr Sect B

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The member n = 3.5 of the series RbxPsWsnO24n+16 has been studied by X-ray diffraction. The structure of a single crystal with the composition Rbl.74PsW28OI00 has been established. The mean structure was solved in the space group P2/c with a = 15.723 (4), b = 3.764 (3), c = 17.118 (4) A, fl = 113.42 (2) °, leading to R = 0.030 and R w = 0.033 for 1512 reflections with I >_ 0"005Ima × and a(I)/I < 0.333. The actual structure can be described with the cell a, 2b, c, space group P21/c. The host lattice of this compound is built up from ReO3-type slabs connected through P207 groups.It can also be described as an ReO3-type framework in which P207 groups replace two octahedra in an ordered manner. A comparison is made between this nonintegral member of the series and the integral members n = 3 and n = 4, especially concerning the distortion of the framework.

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“…94 " 106 In terms of the definition of an oxide bronze advanced earlier, these phases are not true bronzes but are lower ternary or quarternary oxides. However, the acidic P0 4 group is able to react and the resulting phases form the socalled phosphate bronzes.…”

Section: The Phosphate 'Bronzes' and Related Phasesmentioning

confidence: 99%

The Crystal Chemistry of the Higher Tungsten Oxides

Tilley

1995

The Chemistry of Non-Sag Tungsten

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The crystal chemistry of binary and ternary tungsten oxides with overall compositions between M0 3 and approximately M0 2 is reviewed. The chapter focuses primarily upon the reduced oxides and their fully oxidised analogues and descriptions of the structures have been employed which stress the linkage of component metal oxygen polyhedra.The stable form of the parent oxide W0 3 consists of corner-linked W0 6 octahedra. Reduction by way of the addition of metal atoms which can occupy the cage sites between these octahedra leads to the formation of the perovskite structure tungsten bronzes.Slight reduction of the binary oxide with medium sized metal atoms produces compounds containing units of edge-shared octahedra. These materials form the crystallographic shear (CS) phases. At greater degrees of reduction with similar metals pentagonal bipyramidal WÖ 7 polyhedra are utilised to form a variety of pentagonal column (PC) phases. This group includes the tetragonal tungsten bronze (TTB) structure and derivatives thereof.Low temperature preparations have lead to the formation of two other W0 3 structure types based upon rings of corner-sharing octahedra, one of which is the hexagonal tungsten bronze framework and the other the pyrochlore framework. These can be considered as parent structures for the high temperature hexagonal tungsten bronze (HTB) phases, the intergrowth tungsten bronze (ITB) phases and a number of ternary phases with structures related to that of pyrochlore.An extensive group of phases, the so-called 'phosphate tungsten bronzes', are ternary oxides containing phosphate groups, rather than bronzes. They are described in terms of the octahedral and tetrahedral polyhedra from which they are built up and their relationship to Mo 4 O n structure indicated.A concluding section considers some aspects of the stability and reactivity of these phases.

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Rb_xP₈W₃₂O₁₁₂: a tunnel structure built up from ReO₃-type blocks and P₂O₇ groups

Cited by 34 publications

References 9 publications

Phosphate tungsten bronze series: crystallographic and structural properties of low-dimensional conductors

Phosphate tungsten bronze series: crystallographic and structural properties of low-dimensional conductors

Bronzes with a tunnel structure RbxP8W8nO24n+16. III. RbxP8W28O100: a member corresponding to a non-integral n value n = 3.5

The Crystal Chemistry of the Higher Tungsten Oxides

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Rb x P8W32O112: a tunnel structure built up from ReO3-type blocks and P2O7 groups

Cited by 34 publications

References 9 publications

Phosphate tungsten bronze series: crystallographic and structural properties of low-dimensional conductors

Phosphate tungsten bronze series: crystallographic and structural properties of low-dimensional conductors

Bronzes with a tunnel structure RbxP8W8nO24n+16. III. RbxP8W28O100: a member corresponding to a non-integral n value n = 3.5

The Crystal Chemistry of the Higher Tungsten Oxides

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Rb_xP₈W₃₂O₁₁₂: a tunnel structure built up from ReO₃-type blocks and P₂O₇ groups