Microscopic crystallographic analysis of dislocations in molecular crystals

TL;DR

This paper introduces a low-dose, single-exposure electron microscopy technique that enables nanometre-resolved analysis of dislocations in molecular crystals, overcoming previous limitations due to crystal sensitivity.

Contribution

The study presents a novel low-dose electron microscopy method for unambiguously characterizing dislocations in molecular crystals at nanometre resolution.

Findings

Successful identification of dislocation character in various molecular crystals

Revealed slip systems and dislocation behaviors in organic materials

Demonstrated the method's effectiveness across different crystal types

Abstract

Organic molecular crystals encompass a vast range of materials from pharmaceuticals to organic optoelectronics and proteins to waxes in biological and industrial settings. Crystal defects from grain boundaries to dislocations are known to play key roles in mechanisms of growth and also in the functional properties of molecular crystals. In contrast to the precise analysis of individual defects in metals, ceramics, and inorganic semiconductors enabled by electron microscopy, significantly greater ambiguity remains in the experimental determination of individual dislocation character and slip systems in molecular materials. In large part, nanoscale dislocation analysis in molecular crystals has been hindered by the severely constrained electron exposures required to avoid irreversibly degrading these crystals. Here, we present a low-dose, single-exposure approach enabling nanometre-resolved analysis of individual extended dislocations in molecular crystals. We demonstrate the approach for a range of crystal types to reveal dislocation character and operative slip systems unambiguously.