Crystal Structure of Ferroelastic Pb5Al2.96Cr0.04F19 at 300 K

Bravic, G.; Mühll, Régnault von der; Ravez, J.

doi:10.1006/jssc.2000.8945

Cited by 2 publications

(3 citation statements)

References 7 publications

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“…3 Tables S1±S12 present previously published atomic coordinates for phases V, IV and II, as well as the atomic coordinates for phase IV following transformation to the body-centered setting, the re®ned atomic coordinates of phase III in space group P " 1 by Bravic et al (2000) as transformed to I " 1, and the atomic displacements along each axis at all four phase transitions. Fig.…”

Section: Structural Characteristicsmentioning

confidence: 99%

“…The atomic coordinates from x13.3 and those from Table 4 proved to be equally adequate in re®nement, giving the results in x4.2. The coordinates were used later by Bravic et al (2000) as a starting model that led to R = 0.065, based on a set of F obs measured at 300 K from a single crystal with the composition Pb 5 Al 2.96 Cr 0.04 F 19 ; at room temperature, the latter is isostructural with phase III of Pb 5 Al 3 F 19 but differs from it in detail, see x14 and Table S11.…”

Section: Structure Refinement By Use Of Irreducible Representationsmentioning

confidence: 99%

“…S1(a±c) of the supplemetary material. The structure derived hereunder for phase III has also been used by Bravic et al (2000) in a single-crystal re®nement of Pb 5 Al 2.96 Cr 0.04 F 19 , see x14.…”

Section: Introductionmentioning

confidence: 99%

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Structure–property correlation over five phases and four transitions in Pb₅Al₃F₁₉

Abrahams

Ravez

Ritter

et al. 2003

Acta Crystallogr B Struct Sci

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The calorimetric and dielectric properties of Pb(5)Al(3)F(19) in the five phases stable under ambient pressure are correlated with structure for fuller characterization of each phase. The first-order transition between ferroelectric phase V and antiferroelectric phase IV at T(V,IV) = 260 (5) K exhibits a thermal hysteresis of 135 (5) K on heating, with a maximum atomic displacement Delta(xyz)(max) = 1.21 (6) A; the transition from phase IV to ferroelastic phase III at 315 (5) K is also first order but with a thermal hysteresis of 10 (5) K and Delta(xyz)(max) = 0.92 (7) A; that from phase III to paraelastic phase II at 360 (5) K is second order without hysteresis and has Delta(xyz)(max) = 0.69 (4) A; and the transition from phase II to paraelectric phase I at 670 (5) K is second or higher order, with Delta(xyz)(max) = 0.7 (4) A. The measured entropy change DeltaS at T(V,IV) agrees well with DeltaS as derived from the increased configurational energy by Stirling's approximation. For all other phase transitions, 0.5 > or = DeltaS > 0 J mol(-1) K(-1) is consistent with an entropy change caused primarily by the changes in the vibrational energy. The structure of phase III is determined both by group theoretical/normal mode analysis and by consideration of the structures of phases II, IV and V reported previously; refinement is by simultaneous Rietveld analysis of the X-ray and neutron diffraction powder profiles. The structure of prototypic phase I is predicted on the basis of the atomic arrangement in phases II, III, IV and V. The introduction of 3d electrons into the Pb(5)Al(3)F(19) lattice disturbs the structural equilibrium, the addition of 0.04% Cr(3+) causing significant changes in atomic positions and increasing T(IV,III) by approximately 15 K. Substitution of Al(3+) by 20% or more Cr(3+) eliminates the potential minima that otherwise stabilize phases IV, III and II.

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Section: Structural Characteristicsmentioning

confidence: 99%

Section: Structure Refinement By Use Of Irreducible Representationsmentioning

confidence: 99%

See 1 more Smart Citation

Structure–property correlation over five phases and four transitions in Pb₅Al₃F₁₉

Abrahams

Ravez

Ritter

et al. 2003

Acta Crystallogr B Struct Sci

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Zur Kristallstruktur von Ba₃Al₂F₁₂

Kaiser¹,

Babel

2004

Zeitschrift anorg allge chemie

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Inhaltsübersicht. Bei der Darstellung von BaMnAlF 7 erhielten wir als Nebenprodukt Einkristalle von Ba 3 Al 2 F 12 (a ϭ 1020,3(2), b ϭ 988,5(1), c ϭ 952,2(1) pm, Raumgruppe Pnnm, Z ϭ 4). Die erneute Verfeinerung bestätigte die schon bekannte Struktur, lieferte aber verbesserte Ergebnisse (R 1 Ј ϭ 0,028 bzw. wR 2 ϭ 0,06 für 1908 bzw.Abstract. Preparing BaMnAlF 7 we obtained single crystals of Ba 3 Al 2 F 12 as a by-product (a ϭ 1020.3(2), b ϭ 988.5(1), c ϭ 952.2(1) pm, space group Pnnm, Z ϭ 4). The redetermination confirmed the structure already known, but improved the results (R 1 Ј ϭ 0.028 and wR 2 ϭ 0.06 for 1908 and 2717 reflections, resp.).

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Crystal Structure of Ferroelastic Pb5Al2.96Cr0.04F19 at 300 K

Cited by 2 publications

References 7 publications

Structure–property correlation over five phases and four transitions in Pb₅Al₃F₁₉

Structure–property correlation over five phases and four transitions in Pb₅Al₃F₁₉

Zur Kristallstruktur von Ba₃Al₂F₁₂

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Crystal Structure of Ferroelastic Pb5Al2.96Cr0.04F19 at 300 K

Cited by 2 publications

References 7 publications

Structure–property correlation over five phases and four transitions in Pb5Al3F19

Structure–property correlation over five phases and four transitions in Pb5Al3F19

Zur Kristallstruktur von Ba3Al2F12

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Structure–property correlation over five phases and four transitions in Pb₅Al₃F₁₉

Structure–property correlation over five phases and four transitions in Pb₅Al₃F₁₉

Zur Kristallstruktur von Ba₃Al₂F₁₂