Abstract
The low-Q peaks on three pulsed-neutron powder patterns (total, U differential, and Pd differential) of the icosahedral quasicrystal Pd3SiU have been indexed on the basis of an assumed cubic structure of the crystals that by icosahedral twinning form the quasicrystal. The primitive unit cube is found to have edge length 56.20 A and to contain approximately 12,100 atoms. Similar analyses of pulsed-neutron patterns of Al55Cu10Li35, Al55Cu10Li30Mg5, and Al510Cu125Li235Mg130 give values of the cube edge length 58.3, 58.5, and 58.4 A, respectively, with approximately 11,650 atoms in the unit cube. It is suggested that the unit contains eight complexes in the beta-W positions, plus some small interstitial groups of atoms, with each complex consisting of a centered icosahedron of 13 clusters, each of 116 atoms with the icosahedral structure found in the body-centered cubic crystal Mg32(Al,Zn)49.
Full text
PDF
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Kofalt DD, Nanao S, Egami T, Wong KM, Poon SJ. Differential anomalous-x-ray-scattering study of icosahedral and amorphous Pd58.8U20.6Si20.6. Phys Rev Lett. 1986 Jul 7;57(1):114–117. doi: 10.1103/PhysRevLett.57.114. [DOI] [PubMed] [Google Scholar]
- Ma Y, Stern EA, Gayle FW. Structure of icosahedral Al-Cu-Li. Phys Rev Lett. 1987 May 11;58(19):1956–1959. doi: 10.1103/PhysRevLett.58.1956. [DOI] [PubMed] [Google Scholar]
- Pauling L. Additional evidence from x-ray powder diffraction patterns that icosahedral quasi-crystals of intermetallic compounds are twinned cubic crystals. Proc Natl Acad Sci U S A. 1988 Jul;85(13):4587–4590. doi: 10.1073/pnas.85.13.4587. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Pauling L. Additional evidence from x-ray powder diffraction patterns that icosahedral quasi-crystals of intermetallic compounds are twinned cubic crystals. Proc Natl Acad Sci U S A. 1988 Jul;85(13):4587–4590. doi: 10.1073/pnas.85.13.4587. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Pauling L. Evidence from electron micrographs that icosahedral quasicrystals are icosahedral twins of cubic crystals. Proc Natl Acad Sci U S A. 1990 Oct;87(20):7849–7850. doi: 10.1073/pnas.87.20.7849. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Pauling L. Factors determining the average atomic volumes in intermetallic compounds. Proc Natl Acad Sci U S A. 1987 Jul;84(14):4754–4756. doi: 10.1073/pnas.84.14.4754. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Pauling L. Icosahedral quasicrystals of intermetallic compounds are icosahedral twins of cubic crystals of three kinds, consisting of large (about 5000 atoms) icosahedral complexes in either a cubic body-centered or a cubic face-centered arrangement or smaller (about 1350 atoms) icosahedral complexes in the beta-tungsten arrangement. Proc Natl Acad Sci U S A. 1989 Nov;86(22):8595–8599. doi: 10.1073/pnas.86.22.8595. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Pauling L., Kamb B. A revised set of values of single-bond radii derived from the observed interatomic distances in metals by correction for bond number and resonance energy. Proc Natl Acad Sci U S A. 1986 Jun;83(11):3569–3571. doi: 10.1073/pnas.83.11.3569. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Pauling L. Unified structure theory of icosahedral quasicrystals: Evidence from neutron powder diffraction patterns that AlCrFeMnSi, AlCuLiMg, and TiNiFeSi icosahedral quasicrystals are twins of cubic crystals containing about 820 or 1012 atoms in a primitive unit cube. Proc Natl Acad Sci U S A. 1988 Nov;85(22):8376–8380. doi: 10.1073/pnas.85.22.8376. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Shen Y, Dmowski W, Egami T, Poon SJ, Shiflet GJ. Structure of Al-(Li,Mg)-Cu icosahedral alloys studied by pulsed neutron scattering. Phys Rev B Condens Matter. 1988 Jan 15;37(3):1146–1154. doi: 10.1103/physrevb.37.1146. [DOI] [PubMed] [Google Scholar]