High resolution transmission electron microscopy observation of thermally fluctuating phasons in decagonal Al-Cu-Co

In situ high-temperature, high resolution transmission electron microscopy (HRTEM) was performed on an Al-Cu-Co decagonal quasicrystal, to investigate thermal fluctuation of phasons. A tiling pattern constructed from the HRTEM image was analyzed in the framework of the strip-projection method. Transitions between two local tile arrangements were observed at high temperature for the first time, and were shown to correspond to a thermal phason fluctuation.