On the depth resolution of transmission Kikuchi diffraction (TKD) analysis

Junliang Liu; Sergio Lozano-Perez; Angus J Wilkinson; Chris R M Grovenor

doi:10.1016/j.ultramic.2019.06.003

On the depth resolution of transmission Kikuchi diffraction (TKD) analysis

Ultramicroscopy. 2019 Oct:205:5-12. doi: 10.1016/j.ultramic.2019.06.003. Epub 2019 Jun 10.

Authors

Junliang Liu¹, Sergio Lozano-Perez², Angus J Wilkinson², Chris R M Grovenor²

Affiliations

¹ Department of Materials, University of Oxford, Parks Road, OX1 3PH, United Kingdom. Electronic address: bryanchina@hotmail.com.
² Department of Materials, University of Oxford, Parks Road, OX1 3PH, United Kingdom.

PMID: 31234103
DOI: 10.1016/j.ultramic.2019.06.003

Abstract

In this paper, we have analyzed the depth resolution that can be achieved by on-axis transmission Kikuchi diffraction (TKD) using a Zr-Nb alloy. The results indicate that the signals contributing to detectable Kikuchi bands originate from a depth of approximately the mean free path of thermal diffuse scattering (λ_TDS) from the bottom surface of a thin foil sample. This existing surface sensitivity can thus lead to the observation of different grain structures when opposite sides of a nano-crystalline foil are facing the incident electron beam. These results also provide a guideline for the ideal sample thickness for TKD analysis of ≤ 6λ_TDS, or 21 times the elastic scattering mean free path (λ_MFP) for samples of high crystal symmetry. For samples of lower symmetry, a smaller thickness ≤ 3λ_TDS, or ≤ 10λ_MFP is suggested.

Keywords: Depth resolution; Nanocrystalline material; Thermal diffuse scattering; Transmission Kikuchi diffraction (TKD); Zr alloys.