1. Reversible structure manipulation by tuning carrier concentration in metastable Cu₂S (PNAS 114, 9832 (2017))

Structural evolution of a Cu₂S nanoplate under an electron dose-rate cycle at room temperature. (A) Snapshots of the electron diffraction patterns on increasing and decreasing the electron dose rate. Typical real-space lattice images with their FFTs of the (B) semiconducting monoclinic L-s phase and (C) insulating hexagonal H-i phase. In the diffraction series, an L-H–L-H structural transition can be identified when the electron dose rate is monotonically increased, and a reversible H-L–H-L structural transition is recorded as the electron dose rate is monotonically decreased.