Spectroscopic Evidence for Exceptional Thermal Contribution to Electron Beam-Induced Fragmentation

While electron beam-induced fragmentation (EBIF) has been reported to result in the formation of nanocrystals of various compositions, the physical forces driving this phenomenon are still poorly understood. We report EBIF to be a much more general phenomenon than previously appreciated, operative across a wide variety of metals, semiconductors, and insulators. In addition, we leverage the temperature dependent bandgap of several semiconductors, using in situ cathodoluminescence spectroscopy, to quantify the thermal contribution to EBIF and find extreme temperature rises upward of 1000 K

Size-Dependent Polar Ordering in Colloidal GeTe Nanocrystals

The question of the nature and stability of polar ordering in nanoscale ferroelectrics is examined with colloidal nanocrystals of germanium telluride (GeTe). We provide atomic-scale evidence for room-temperature polar ordering in individual nanocrystals using aberration-corrected transmission electron microscopy and demonstrate a reversible, size-dependent polar-nonpolar phase transition of displacive character in nanocrystal ensembles. A substantial linear component of the distortion is observed, which is in contrast with theoretical reports predicting a toroidal state