From Quasicrystals to Crystals with Interpenetrating Icosahedra in Ca–Au–Al: In Situ Variable-Temperature Transformation
dc.contributor.author | Pham, Joyce | |
dc.contributor.author | Meng, Fanqiang | |
dc.contributor.author | Lynn, Matthew | |
dc.contributor.author | Miller, Gordon | |
dc.contributor.author | Ma, Tao | |
dc.contributor.author | Kreyssig, Andreas | |
dc.contributor.author | Kramer, Matthew | |
dc.contributor.author | Goldman, Alan | |
dc.contributor.author | Miller, Gordon | |
dc.contributor.department | Ames National Laboratory | |
dc.contributor.department | Physics and Astronomy | |
dc.date | 2019-12-10T20:18:43.000 | |
dc.date.accessioned | 2020-06-29T23:23:36Z | |
dc.date.available | 2020-06-29T23:23:36Z | |
dc.date.issued | 2018-01-01 | |
dc.description.abstract | <p>The irreversible transformation from an icosahedral quasicrystal (i-QC) CaAu4.39Al1.61 to its cubic 2/1 crystalline approximant (CA) Ca13Au56.31(3)Al21.69 (CaAu4.33(1)Al1.67, <em>Pa</em>3̅ (No. 205); Pearson symbol: <em>cP</em>728; <em>a</em> = 23.8934(4)), starting at ∼570 °C and complete by ∼650 °C, is discovered from in situ, high-energy, variable-temperature powder X-ray diffraction (PXRD), thereby providing direct experimental evidence for the relationship between QCs and their associated CAs. The new cubic phase crystallizes in a Tsai-type approximant structure under the broader classification of polar intermetallic compounds, in which atoms of different electronegativities, viz., electronegative Au + Al vs electropositive Ca, are arranged in concentric shells. From a structural chemical perspective, the outermost shell of this cubic approximant may be described as interpenetrating and edge-sharing icosahedra, a perspective that is obtained by splitting the traditional structural description of this shell as a 92-atom rhombic triacontahedron into an 80-vertex cage of primarily Au [Au59.86(2)Al17.14□3.00] and an icosahedral shell of only Al [Al10.5□1.5]. Following the proposal that the cubic 2/1 CA approximates the structure of the i-QC and on the basis of the observed transformation, an atomic site analysis of the 2/1 CA, which shows a preference to maximize the number of heteroatomic Au–Al nearest neighbor contacts over homoatomic Al–Al contacts, implies a similar outcome for the i-QC structure. Analysis of the most intense reflections in the diffraction pattern of the cubic 2/1 CA that changed during the phase transformation shows correlations with icosahedral symmetry, and the stability of this cubic phase is assessed using valence electron counts. According to electronic structure calculations, a cubic 1/1 CA, “Ca24Au88Al64” (CaAu3.67Al2.67) is proposed.</p> | |
dc.identifier | archive/lib.dr.iastate.edu/ameslab_manuscripts/508/ | |
dc.identifier.articleid | 1511 | |
dc.identifier.contextkey | 15968536 | |
dc.identifier.s3bucket | isulib-bepress-aws-west | |
dc.identifier.submissionpath | ameslab_manuscripts/508 | |
dc.identifier.uri | https://dr.lib.iastate.edu/handle/20.500.12876/7436 | |
dc.language.iso | en | |
dc.relation.ispartofseries | IS-J 9592 | |
dc.source.bitstream | archive/lib.dr.iastate.edu/ameslab_manuscripts/508/IS_J_9592.pdf|||Sat Jan 15 00:42:32 UTC 2022 | |
dc.source.uri | 10.1021/jacs.7b10358 | |
dc.subject.disciplines | Condensed Matter Physics | |
dc.title | From Quasicrystals to Crystals with Interpenetrating Icosahedra in Ca–Au–Al: In Situ Variable-Temperature Transformation | |
dc.type | article | |
dc.type.genre | article | |
dspace.entity.type | Publication | |
relation.isAuthorOfPublication | 2ae7cd46-13ac-44c3-af5d-86458fb38962 | |
relation.isOrgUnitOfPublication | 25913818-6714-4be5-89a6-f70c8facdf7e | |
relation.isOrgUnitOfPublication | 4a05cd4d-8749-4cff-96b1-32eca381d930 |
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