The crystal structure of triclinic WO<sub>3</sub>

Diehl, R.; Brandt, G.; Salje, Ekhard K. H.

doi:10.1107/s0567740878005014

Cited by 199 publications

(97 citation statements)

References 11 publications

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“…From the simple overlap analysis given thus far one would expect WO3 to have a cubic structure. In fact, even though WO3 undergoes at least four phase transitions between 0 and 950K, an octahedral tilting distortion is always present, along with a displacement of the tungstens from the center of the octahedra (Salje, 1977;Diehl, Brandt & Salje, 1978;Woodward, Sleight & Vogt, 1995). In this compound no A---O interactions are present, therefore, M--O bonding forces must be responsible for the observed distortions from cubic symmetry.…”

Section: Sno~-lattice Show That a 180 ° M---o---m Bond Anglementioning

confidence: 99%

Octahedral Tilting in Perovskites. II. Structure Stabilizing Forces

Woodward¹

1997

Acta Crystallogr B Struct Sci

626

480

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The 23 Glazer tilt systems describing octahedral tilting in perovskites have been investigated. The various tilt systems have been compared in terms of their A-cation coordination and it is shown that those tilt systems in which all the A-cation sites remain crystallographically equivalent are strongly favored, when all the A sites are occupied by the same ion. Calculations based on both ionic and covalent models have been performed to compare the seven equivalent A-site tilt systems. Both methods predict that when the tilt angles become large, the orthorhombic a+b-b -tilt system will result in the lowest energy structure. This tilt system gives the lowest energy structure because it maximizes the number of short A---O interactions. The rhombohedral a-a-a-tilt system gives a structure with a slightly lower Madelung energy, but increased ion-ion repulsions destabilize this structure as the tilt angles increase. Consequently, it is stabilized by highly charged A cations and small to moderate tilt angles. The ideal cubic a°a°a° tilt system is only observed when stabilized by oversized A cations and/or M---O 7r-bonding. Tilt systems with nonequivalent A-site environments are observed when at least two A cations with different sizes and/or bonding preferences are present. In these compounds the ratio of large-to-small cations dictates the most stable tilt system.

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Section: Sno~-lattice Show That a 180 ° M---o---m Bond Anglementioning

confidence: 99%

Octahedral Tilting in Perovskites. II. Structure Stabilizing Forces

Woodward¹

1997

Acta Crystallogr B Struct Sci

626

480

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“…As for the WO]-portion of the Sb2WO6 structure, it would appear that all these polymorphs are characterized by essentially regular, corner-connected WO6 octahedra in which the W atoms are appreciably off-centre (Diehl, Brandt & Salje, 1978;Loopstra & Boldrini, 1966;Salje, 1977). A rather similar antiferroelectric pattern of tungsten movement to that observed in Sb2WO6 occurs in the room-temperature triclinic form of WO3 [viewed on its (101) plane (Diehl et al, 1978)]. The crystal chemistry underlying this phenomenon would appear to be an important problem in solid-state chemistry.…”

Section: Structure Refinement Of Sb2 W06mentioning

confidence: 99%

Antiferroelectric modulations in Sb₂WO₆ and Sb₂MoO₆

Ling¹,

Withers²,

Rae³

et al. 1996

Acta Crystallogr Sect B

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The structure of Sb2WO6 [Mr = 523.4, triclinic, F1, a = 11.132 (1), b = 9.896 (4), c = 18.482 (7)/~, a = 90.20 (4), /3 -96.87 (8), q, = 90.21 (5) °, Dx = 6.88 g cm -3, Z = 16, Mo Ka, A = 0.7107/~,, /z = 338.5cm -I, F(000)= 3536] has been refined as an enlarged 2a x 2b x 2c F-centred superstructure of the previously reported structure [Castro, Millan, Enjalbert, Snoeck & Galy (1994). Mat. Res. Bull. 29,[871][872][873][874][875][876][877][878][879]

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“…1. A monoclinic phase (P 2 1 /n) 60 [21] and a triclinic phase P1 exist at room temperature 61 [25,26]. At higher temperatures, Vogt et al [22] and Locherer 62 et al [19] concluded a transition from P bcn to the P 4/ncc 63 phase and Howard et al [23] observed an intermediate P 2 1 /c 64 phase.…”

mentioning

confidence: 99%

First-principles reinvestigation of bulk WO3

et al. 2016

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6Using first-principles calculations, we analyze the structural properties of tungsten trioxide WO 3 . Our calculations rely on density functional theory and the use of the B1-WC hybrid functional, which provides very good agreement with experimental data. We show that the hypothetical high-symmetry cubic reference structure combines several ferroelectric and antiferrodistortive (antipolar cation motions, rotations, and tilts of oxygen octahedra) structural instabilities. Although the ferroelectric instability is the largest, the instability related to antipolar W motions combines with those associated to oxygen rotations and tilts to produce the biggest energy reduction, yielding a P 2 1 /c ground state. This nonpolar P 2 1 /c phase is only different from the experimentally reported P c ground state by the absence of a very tiny additional ferroelectric distortion. The calculations performed on a stoichiometric compound so suggest that the low-temperature phase of WO 3 is not intrinsically ferroelectric and that the experimentally observed ferroelectric character might arise from extrinsic defects such as oxygen vacancies. Independently, we also identify never observed R3m and R3c ferroelectric metastable phases with large polarizations and low energies close to the P 2 1 /c ground state, which makes WO 3 a potential antiferroelectric material. The relative stability of various phases is discussed in terms of the anharmonic couplings between different structural distortions, highlighting a very complex interplay.

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The crystal structure of triclinic WO₃

Cited by 199 publications

References 11 publications

Octahedral Tilting in Perovskites. II. Structure Stabilizing Forces

Octahedral Tilting in Perovskites. II. Structure Stabilizing Forces

Antiferroelectric modulations in Sb₂WO₆ and Sb₂MoO₆

First-principles reinvestigation of bulk WO3

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The crystal structure of triclinic WO3

Cited by 199 publications

References 11 publications

Octahedral Tilting in Perovskites. II. Structure Stabilizing Forces

Octahedral Tilting in Perovskites. II. Structure Stabilizing Forces

Antiferroelectric modulations in Sb2WO6 and Sb2MoO6

First-principles reinvestigation of bulk WO3

Contact Info

Product

Resources

About

The crystal structure of triclinic WO₃

Antiferroelectric modulations in Sb₂WO₆ and Sb₂MoO₆