Effects of pressure on the local atomic structure of CaWO4 and YLiF4: mechanism of the scheelite-to-wolframite and scheelite-to-fergusonite transitions

Errandonea, Daniel; Manjón, F. J.; Somayazulu, Maddury; Häusermann, Daniel M.

doi:10.1016/j.jssc.2003.10.017

Cited by 87 publications

(78 citation statements)

References 52 publications

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“…2 at 2θ = 4.2° and at 2θ = 12.8 °. These facts are indicative of a structural phase transition around 12.2(9) GPa, which is in agreement with previous Raman observations [25] and with the transition pressure estimated from the MoO 4 /Sr radii ratio [39].…”

Section: Resultssupporting

confidence: 92%

High-pressure X-ray diffraction study of SrMoO4 and pressure-induced structural changes

Errandonea

Kumar

et al. 2008

Journal of Solid State Chemistry

101

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SrMoO 4 was studied under compression up to 25 GPa by angle-dispersive xray diffraction. A phase transition was observed from the scheelite-structured ambient phase to a monoclinic fergusonite phase at 12.2(9) GPa with cell parameters a = 5.265 (9) Å, b = 11.191(9) Å, c = 5.195 (5) Å, and β = 90.9°, Z = 4 at 13.1 GPa. There is no significant volume collapse at the phase transition. No additional phase transitions were observed and on release of pressure the initial phase is recovered, implying that the observed structural modifications are reversible. The reported transition appeared to be a ferroelastic second-order transformation producing a structure that is a monoclinic distortion of the low-pressure phase and was previously observed in compounds isostructural to SrMoO 4 . A possible mechanism for the transition is proposed and its character is discussed in terms of the present data and the Landau theory. Finally, the EOS is reported and the anisotropic compressibility of the studied crystal is discussed in terms of the compression of the Sr-O and Mo-O bonds.

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Section: Resultssupporting

confidence: 92%

High-pressure X-ray diffraction study of SrMoO4 and pressure-induced structural changes

Errandonea

Kumar

et al. 2008

Journal of Solid State Chemistry

101

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“…Our X-ray diffraction data refute the EXAFS study of the phase transition in SrWO 4 , in which the wolframite phase (P2/c, Z = 2), taken by MgWO 4 at ambient conditions, has been postulated [14]. Recently, Errandonea et al [7] have argued the scheelitewolframite phase transition in CaWO 4 above 11 GPa based on the energy-dispersive X-ray powder diffraction data. In their latest unpublished data, however, Errandonea et al [15] have found out that the pressure-induced post-scheelite polymorphs of CaWO 4 and SrWO 4 are fergusonites using angledispersive X-ray powder diffraction.…”

Section: Discussionsupporting

confidence: 83%

“…1 and 3). They correspond neither to the fergusonite type nor to the PbWO 4 -III (P2 1 /n, Z = 8), LaTaO 4 (P2 1 /c, Z = 4), HgWO 4 (C2/c, Z = 4), or BaMnF 4 (Cmc2 1 , Z = 4) types previously considered as candidates for the pressure-induced post-scheelite structures [2,7]. Moreover, the patterns collected between 15 and 20.7 GPa cannot be indexed on a basis of a single SrWO 4 phase (i.e., see Fig.…”

Section: Resultsmentioning

confidence: 93%

SrWO₄ at high pressures

Grzechnik

Crichton

Hanfland

2005

Physica Status Solidi (b)

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Room-temperature high-pressure behaviour of SrWO 4 scheelite (I4 1 /a, Z = 4) has been studied to 20.7 GPa in a diamond anvil cell using synchrotron angle-dispersive X-ray powder diffraction. Above 10 GPa, it transforms to the fergusonite structure (I2/a, Z = 4). Both scheelite and fergusonite types are ordered superstructures of fluorite (Fm3m, Z = 4). There is no significant volume collapse at the scheelitefergusonite phase transition. However, the compression data including both phases of strontium tungstate cannot be fitted by a common Birch -Murnaghan equation of state. An onset of decomposition into component oxides occurs at about 15 GPa. The pressure-induced transformations are irreversible.

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“…2a it can be seen that the monoclinic strains 11 ε and 33 ε are in absolute value considerable larger than 22 ε . This fact is coherent with the idea that a displacement of the atomic layers of the scheelite phase along the [100] or [010] directions is involved in the scheelite-to-fergusonite transition [14]. The differences between the diagonal components of the monoclinic strain tensor are a natural consequence of the fact that compression of the fergusonite phase of the compounds typified by CaWO 4 is very anisotropic [16,17,21].…”

Section: Spontaneous Strainssupporting

confidence: 75%

Landau theory applied to phase transitions in calcium orthotungstate and isostructural compounds

Errandonea¹

2007

Europhys. Lett.

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Effects of pressure on the local atomic structure of CaWO4 and YLiF4: mechanism of the scheelite-to-wolframite and scheelite-to-fergusonite transitions

Cited by 87 publications

References 52 publications

High-pressure X-ray diffraction study of SrMoO4 and pressure-induced structural changes

High-pressure X-ray diffraction study of SrMoO4 and pressure-induced structural changes

SrWO₄ at high pressures

Landau theory applied to phase transitions in calcium orthotungstate and isostructural compounds

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Effects of pressure on the local atomic structure of CaWO4 and YLiF4: mechanism of the scheelite-to-wolframite and scheelite-to-fergusonite transitions

Cited by 87 publications

References 52 publications

High-pressure X-ray diffraction study of SrMoO4 and pressure-induced structural changes

High-pressure X-ray diffraction study of SrMoO4 and pressure-induced structural changes

SrWO4 at high pressures

Landau theory applied to phase transitions in calcium orthotungstate and isostructural compounds

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SrWO₄ at high pressures