| Reference Type | Journal (article/letter/editorial) |
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| Title | Haüyne: phase transition and high-temperature structures obtained from synchrotron radiation and Rietveld refinements |
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| Journal | Mineralogical Magazine |
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| Authors | Hassan, I. | Author |
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| Antao, S. M. | Author |
| Parise, J. B. | Author |
| Year | 2004 (June) | Volume | 68 |
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| Issue | 3 |
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| Publisher | Mineralogical Society |
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| DOI | doi:10.1180/0026461046830201Search in ResearchGate |
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| Generate Citation Formats |
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| Mindat Ref. ID | 243552 | Long-form Identifier | mindat:1:5:243552:1 |
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| GUID | 0 |
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| Full Reference | Hassan, I., Antao, S. M., Parise, J. B. (2004) Haüyne: phase transition and high-temperature structures obtained from synchrotron radiation and Rietveld refinements. Mineralogical Magazine, 68 (3) 499-513 doi:10.1180/0026461046830201 |
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| Plain Text | Hassan, I., Antao, S. M., Parise, J. B. (2004) Haüyne: phase transition and high-temperature structures obtained from synchrotron radiation and Rietveld refinements. Mineralogical Magazine, 68 (3) 499-513 doi:10.1180/0026461046830201 |
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| Abstract/Notes | AbstractThe structural behaviour of a haüyne with a chemical composition of Na4.35Ca2.28K0.95[Al6Si6O24]- (SO4)2.03, at room pressure and from 33 to 1035°C on heating, was determined by using in situ synchrotron X-ray powder diffraction data (λ = 0.92249(5) Å). The satellite reflections in haüyne are lost at ∼400°C and a true substructure results because of this phase transition. There is a discontinuity in the a unit-cell parameter at ∼585°C. The α parameter increases rapidly and non-linearly to 585°C, but above 585°C, the expansion rate decreases. The percent volume change between 33 and 576°C is 2.0(3)%, and 0.6(3)% between 593 and 1035°C. Between 33 and 1035°C, the Al–O, Si–O and S–O distances are constant. Between 33 and 576°C, the angle of rotation of the AlO4 tetrahedron, jAl, changesfrom 11.5 to 5.8°, while the angle of rotation of the SiO4 tetrahedron, φSi, changesfrom 12.4 to 6.3°. The Al–O–Si bridging angle changesfrom 150.05(2) to 153.08(1)° from 33 to 576°C. Beyond 585°C, φAl and φSi angles remain nearly constant even though the maximum rotation of the tetrahedra is not achieved. Moreover, the Al–O–Si angle continues to increase at a slower rate from 585 to 1035°C by 1.05(2)°. From 33 to ∼585°C, the K atom position migrates at a slower rate than the Na and Ca atoms, and the structure expands at a high rate. Beyond 585°C, all the atomic positions of the interstitial cations (Na+, K+, Ca2+) remain nearly constant and the expansion of the structure is retarded. |
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