Automated detection and mapping of crystal tilt using thermal diffuse scattering in transmission electron microscopy

TL;DR

This paper introduces a new automated method to accurately determine local crystal tilt in transmission electron microscopy using Kikuchi band analysis of diffraction patterns, enabling high-resolution orientation mapping over large areas.

Contribution

The paper presents a geometric analysis technique for Kikuchi bands to determine crystal tilt from TEM diffraction data, implemented in automated software for practical applications.

Findings

Achieves approximately 0.1 mrad accuracy in tilt measurement

Successfully applied to high-Mn steel and epitaxial interfaces

Enables tilt mapping over fields of view larger than 100 nm

Abstract

Quantitative interpretation of transmission electron microscopy (TEM) data of crystalline specimens often requires the accurate knowledge of the local crystal orientation. A method is presented which exploits momentum-resolved scanning TEM (STEM) data to determine the local mistilt from a major zone axis. It is based on a geometric analysis of Kikuchi bands within a single diffraction pattern, yielding the centre of the Laue circle. Whereas the approach is not limited to convergent illumination, it is here developed using unit-cell averaged diffraction patterns corresponding to high-resolution STEM settings. In simulation studies, an accuracy of approximately 0.1mrad is found. The method is implemented in automated software and applied to crystallographic tilt and in-plane rotation mapping in two experimental cases. In particular, orientation maps of high-Mn steel and an epitaxially grown La$_{\text{0.7}}$Sr$_{\text{0.3}}$MnO$_{\text{3}}$-SrTiO$_{\text{3}}$ interface are presented. The results confirm the estimates of the simulation study and indicate that tilt mapping can be performed consistently over a wide field of view with diameters well above 100nm at unit cell real space sampling.