Size-dependent polar ordering in colloidal GeTe nanocrystals

Nano Lett. 2011 Mar 9;11(3):1147-52. doi: 10.1021/nl104075v. Epub 2011 Feb 21.

Abstract

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.