Formation of Metastable Silver Nanowires of Hexagonal Structure and Their Structural Transformation under Electron Beam Irradiation

We fabricated Ag nanowires (AgNWs) of 4H hexagonal structure with a diameter of ca. 20 nm using dc electrodeposition inside an anodic alumina oxide (AAO) membrane at low current density. 4H-AgNWs were formed in scale inside an AAO membrane with a pore diameter of ca. 20 nm. We propose that a small-pore-size AAO membrane and appropriate growth conditions favor the growth of 4H-Ag. Transmission electron microscopy (TEM) revealed the coexistence of single-crystalline 4H-AgNWs and fcc-AgNWs. The 4H-AgNWs tended to transform into fcc Ag particles under intense electron beam (EB) irradiation, which may be attributed to the knock-on displacement of Ag atoms by electrons generating defects.