Note on the Structures of MIV P2O7 (MIV = Ge, Zr, and U).

Hagman, Lars‐Ove; Kierkegaard, Peder; Rasmussen, Svend Erik; Smidsrød, Olav; Lindberg, Alf A.; Jansen, Gert; Lamm, Bo; Samuelsson, Benny

doi:10.3891/acta.chem.scand.23-0327

Cited by 32 publications

(10 citation statements)

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“…This matter was resolved by Vo È llenke et al (1963), who described a 3 Â 3 Â 3 supercell of GeP 2 O 7 and thus showed that a superstructure could accommodate bent MÐ OÐM bonds. Similar supercells have been reported for TiP 2 O 7 (Vo È llenke et al, 1963;Sanz et al, 1997), ZrP 2 O 7 (Hagman & Kierkegaard, 1969;Chaunac, 1971;Pascard et al, 1971;Khosrovani et al, 1996) and ZrV 2 O 7 (Korthuis et al, 1995;Khosrovani et al, 1997). At high temperature, the superstructure peaks disappear and the structures can be described using the small unit cell with space group Pa " 3.…”

Section: Introductionsupporting

confidence: 76%

High-pressure properties of TiP₂O₇, ZrP₂O₇and ZrV₂O₇

Carlson

Andersen²

2001

J Appl Crystallogr

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High‐pressure synchrotron X‐ray powder diffraction studies of TiP2O7, ZrP2O7 and ZrV2O7 have been performed. The ZrV2O7 structure undergoes a reversible transition at 1.38–1.58 GPa from cubic α‐ to pseudo‐tetragonal β‐ZrV2O7 that displays an orthorhombic 2 × 3 × 3 supercell. At pressures above 4 GPa, ZrV2O7 becomes irreversibly X‐ray amorphous. No such transformations are observed for TiP2O7 and ZrP2O7, which compress smoothly up to the highest investigated pressures (40.3 and 20.5 GPa, respectively). These differences in high‐pressure properties are discussed in terms of the negative thermal expansion of ZrV2O7. The bulk moduli at ambient pressure (B0) for TiP2O7, ZrP2O7, α‐ZrV2O7 and β‐ZrV2O7 were estimated to be 42 (3), 39 (1), 17.0 (7) and 20.8 (10) GPa, respectively.

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Section: Introductionsupporting

confidence: 76%

High-pressure properties of TiP₂O₇, ZrP₂O₇and ZrV₂O₇

Carlson

Andersen²

2001

J Appl Crystallogr

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“…Studying Weissenberg pictures of a GeP O single crystal (3), a 3;3;3, Z"108, supercell was found that was also cubic within experimental error of that time. A careful study of the powder patterns for M"Si, Sn, Pb, Ti, Zr, Hf, and U compounds also showed similar supercells (3,4); these supercells were con"rmed for M"Ge, Zr, and U by indexing of Guinier-HaK gg photographs taken with strictly monochromatic CuK radiation (4). A landmark in the study of these compounds was the 3;3;3 superstructure determination of SiP O from single crystal data [a"22.418 A > , Pa3 ] (5).…”

Section: There Is a Recent Interest In M'4x4mentioning

confidence: 99%

Syntheses, Structures, and Thermal Expansion of Germanium Pyrophosphates

Losilla

Cabeza

Bruque

et al. 2001

Journal of Solid State Chemistry

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“…Polymorphic behavior has been noted for a large number of the com~ounds having this formulation (10)(11)(12)(13). The Lcrystallograpuhy of systems with the stoichiometry of MX207 is less well explored but again a number of polymorphs have been reported (14,15). On the other hand, the crystallographic nature of compounds with composition M4X207 has been rather ignored, report& f i r Na4P207, (4-6) Li4P207 (16,17) and Li4As207 (17).…”

Section: Introductionmentioning

confidence: 99%

Crystal Structure and Phase Transformations of Sodium Diarsenate, Na₄As₂O₇

Leung¹,

Calvo²

1973

Can. J. Chem.

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Sodium diarsenate at room temperature is monoclinic with lattice parameters a = 5.969(1), b = 10.126(1), c = 12.272(3) A and P = 92.87(2)". There are four formula units per cell with space group C2/c. The structure was refined by full-matrix least-squares to a final R value of 0.027 utilizing 1157 reflections measured on a Syntex P i automatic diffractometer. The anion, consisting of two AsO, tetrahedra sharing a common oxygen atom, with a bridging angle of 123.5" at that oxygen atom, lies on a two-fold axis. The bridging As-0 bond lengths are 1.783 A and the average terminal As-0 bond length is 1.658 8, uncorrected for thermal motion. Both Na ions show fivefold coordination to oxygen atoms. One of these sodium ions has a long interaction (2.852 A) with the bridging oxygen atom of the anion. Na,As207 undergoes a series of phase transformations between room temperature and 220 "C, and a further major transformation near 680 "C.Le sodium diarsenate est monoclinique a la temperature ambiante avec comme parametres du reseau a = 5.969(1), b = 10.126(1), c = 12.272(3) A et P = 92.87(2)". La maille contient quatre unites et le groupe spatial est C2/c. La structure a ete raffinte par la matrice des moindres carres jusqu'a une valeur finale R de 0.027, apres utilisation de 1157 reflexions mesurtes sur un diffractometre Syntex Pi auto-

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Note on the Structures of MIV P2O7 (MIV = Ge, Zr, and U).

Cited by 32 publications

References 0 publications

High-pressure properties of TiP₂O₇, ZrP₂O₇and ZrV₂O₇

High-pressure properties of TiP₂O₇, ZrP₂O₇and ZrV₂O₇

Syntheses, Structures, and Thermal Expansion of Germanium Pyrophosphates

Crystal Structure and Phase Transformations of Sodium Diarsenate, Na₄As₂O₇

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Note on the Structures of MIV P2O7 (MIV = Ge, Zr, and U).

Cited by 32 publications

References 0 publications

High-pressure properties of TiP2O7, ZrP2O7and ZrV2O7

High-pressure properties of TiP2O7, ZrP2O7and ZrV2O7

Syntheses, Structures, and Thermal Expansion of Germanium Pyrophosphates

Crystal Structure and Phase Transformations of Sodium Diarsenate, Na4As2O7

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High-pressure properties of TiP₂O₇, ZrP₂O₇and ZrV₂O₇

High-pressure properties of TiP₂O₇, ZrP₂O₇and ZrV₂O₇

Crystal Structure and Phase Transformations of Sodium Diarsenate, Na₄As₂O₇