Electron microscopy of quasicrystals - where are the atoms?

Quasicrystals represent aperiodically ordered form of solids with symmetries long thought forbidden in nature. Since their discovery, the fundamental key question has been where are the atoms? in these novel aperiodic solids, and electron microscopy has indeed provided images of real atomic arrangements in quasicrystals. In this tutorial review, we describe the microscopic view of quasicrystals using state-of-the-art scanning transmission electron microscopy, providing intriguing details that had never been unveiled by the early diffraction-based structural analyses.