Pushing the limits of STEM analysis and its application toward the characterization of nanocrystals and nanomaterials

Abstract

Aberration-corrected scanning transmission electron microscopes (STEM) have become widely available at user facilities over the past 20 years, enabling significant advancements in the analysis of nanomaterials. Aberration-corrected STEM offers a rich array of newly available atomic-resolution data, the analysis of which requires the development of new methods and models. Toward this end, the work presented in this document pushes the limits of aberration-corrected STEM for the atomic-scale structural and compositional characterization of nanocrystals and nanomaterials and introduces new methods for the interpretation of this data. The projects presented here include an evaluation of the effects of specimen tilt on the visibility of dopant atoms in doped nanocrystals, the development of an improved background fitting method for STEM-EEL spectra, the development of a method for quantifying the 3D radial distribution of elements in spherical core/shell nanocrystals, and preliminary results of the crystallographic analysis of a new bimetallic phase of Mn-Ga.