A 6D structure model for face-centred icosahedral quasicrystals consisting of so-called pseudo-Mackay and mini-Bergman-type atomic clusters is proposed based on the structure model of the AlPdCrFe 3/2 cubic approximant crystal (with space group Pa3, a = 40.5 Å) [Fujita et al. (2013). Acta Cryst. A69, 322-340]. The cluster centres form an icosahedral close sphere packing generated by the occupation domains similar to those in the model proposed by Katz & Gratias [J. Non-Cryst. Solids (1993), 153-154, 187-195], but their size is smaller by a factor τ [τ = (1 + (5))/2]. The clusters cover approximately 99.46% of the atomic structure, and the cluster arrangement exhibits 15 and 19 different local configurations, respectively, for the pseudo-Mackay and mini-Bergman-type clusters. The occupation domains that generate cluster shells are modelled and discussed in terms of structural disorder and local reorganization of the cluster arrangements (phason flip).
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http://dx.doi.org/10.1107/S2053273324008568 | DOI Listing |
Acta Crystallogr A Found Adv
November 2024
National Institute for Materials Science, Tsukuba, Ibaraki, 305, Japan.
A 6D structure model for face-centred icosahedral quasicrystals consisting of so-called pseudo-Mackay and mini-Bergman-type atomic clusters is proposed based on the structure model of the AlPdCrFe 3/2 cubic approximant crystal (with space group Pa3, a = 40.5 Å) [Fujita et al. (2013).
View Article and Find Full Text PDFRSC Adv
August 2024
Physics Department, King's College London Strand WC2R 2LS UK.
We compare the assembly of individual Au nanoparticles in a vacuum and between two Au(111) surfaces classical molecular dynamics on a timescale of 100 ns. In a vacuum, the assembly of three nanoparticles used as seeds, initially showing decahedral, truncated octahedral and icosahedral shapes with a diameter of 1.5-1.
View Article and Find Full Text PDFNanoscale Horiz
December 2023
Nanomaterials Lab, Swansea University, Bay Campus, Fabian Way, Swansea SA1 8EN, UK.
The multi-dimensional potential energy surface (PES) of a nanoparticle, such as a bare cluster of metal atoms, controls both the structure and dynamic behaviour of the particle. These properties are the subject of numerous theoretical simulations. However, quantitative experimental measurements of critical PES parameters are needed to regulate the models employed in the theoretical work.
View Article and Find Full Text PDFPhys Chem Chem Phys
January 2019
Instituto de Química Física Rocasolano, Consejo Superior de Investigaciones Científicas, CSIC, Calle Serrano 119, 28006 Madrid, Spain.
Crystal nucleation of repulsive hard-dumbbells from the sphere to the two tangent spheres limit is investigated at moderately high metastability by brute-force molecular dynamics simulations. Nucleation rates are in good agreement with previous simulations of hard-spheres and dumbbells. Icosahedral structures formed by twinned face-centred-cubic tetrahedra sharing five-fold symmetry axes and icosahedral centers are often found in spheres and dumbbells with either small (L/σ = 0.
View Article and Find Full Text PDFNat Mater
January 2015
1] Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA [2] Applied Physics Program, University of Michigan, Ann Arbor, Michigan 48109, USA [3] Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA.
Icosahedral quasicrystals (IQCs) are a form of matter that is ordered but not periodic in any direction. All reported IQCs are intermetallic compounds and either of face-centred-icosahedral or primitive-icosahedral type, and the positions of their atoms have been resolved from diffraction data. However, unlike axially symmetric quasicrystals, IQCs have not been observed in non-atomic (that is, micellar or nanoparticle) systems, where real-space information would be directly available.
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