ELECTRON MICROSCOPY OF QUASICRYSTALS AND THE VALIDITY OF THE TILING APPROACH

Abstract

A review is presented of high-resolution transmission electron microscopic studies on icosahedral, decagonal and dodecagonal quasicrystals executed during the last eight years, especially at ETH Zürich, with special consideration of the use made of tilings for the interpretation of the electron microscopic image contrast. Since the contrast contains information on the projected potential of the quasicrystal structure, the local details of decorated and undecorated tilings can be correlated to the image contrast. These tilings can even be superimposed directly onto the micrographs as an aid in structural interpretation. Also, tilings can directly be constructed by computer on the basis of contrast maxima or minima appearing in the image. These tilings serve to differentiate between quasiperiodic tiling and random tiling quasicrystal structures. Examples of the successful application of these types of tilings in the structural interpretation of electron microscopic observations on quasicrystal alloys are presented.