J. Phys. Colloques
Volume 50, Number C8, Novembre 198936th International Field Emission Symposium
|Page(s)||C8-259 - C8-263|
J. Phys. Colloques 50 (1989) C8-259-C8-263
FIELD ION MICROSCOPE IMAGE SIMULATIONS FOR ICOSAHEDRAL Al-MnA.J. MELMED1, 2, H.B. ELSWIJK1, 3 et H.A. FOWLER4
1 Surface Science Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, U.S.A.
2 Custom Probes Unlimited, P.O. Box 3938, Gaithersburg, MD 20878 USA
3 c/o Philips Research Laboratories, P.O. Box 80000, NL-5600JA Eindhoven, The Netherlands
4 Center for Computing and Applied Mathematics, National Institute of Standards and Technology, Gaithersburg, MD 20899, U.S.A.
New computer simulations of FIM images for the icosahedral phase of Al-Mn, using the Moore-Ranganathan-shell method, are presented and compared to the experimentally observed images. The closest agreement found thus far is for a cubic model having a 3.32 nm unit cell edge and containing an icosahedral inner atomic motif, with all Mn and only some of the Al atoms included in the simulated images. (An octahedral-motif decoration of a perfect 3-D Penrose model was also tested for comparison.) This surprising result can be understood as the result of inner-cell motif domination over the parent cubic features, due to the very large unit cell size.