Limitations to the measurement of oxygen concentrations by HRTEM imposed by surface roughness

Andrew R. Lupini, Matthew F. Chisholm, Klaus Van Benthem, Leslie J. Allen, Mark P. Oxley, Scott D. Findlay, Maria Varela, Stephen J. Pennycook, Chun Lin Jia, Markus Lentzen, Knut Urban

Research output: Contribution to journalLetterOtherpeer-review

2 Citations (Scopus)

Abstract

In an article published in Microscopy and Microanalysis recently (Jia et al., 2004), it was claimed that aberration-corrected high resolution transmission electron microscopy (HRTEM) allows the quantitative measurement of oxygen concentrations in ceramic materials with atomic resolution. Similar claims have recently appeared elsewhere, based on images obtained through aberration correction (Jia et al., 2003; Jia & Urban, 2004) or very high voltages (Zhang et al., 2003). Seeing oxygen columns is a significant achievement of great importance (Spence, 2003) that will doubtlessly allow some exciting new science; however, other models could provide a better explanation for some of the experimental data than variations in the oxygen concentration. Quantification of the oxygen concentrations was attempted by comparing experimental images with simulations in which the fractional occupancy in individual oxygen columns was reduced. The results were interpreted as representing nonstoichiometry within the bulk and at grain boundaries. This is plausible because previous studies have shown that grain boundaries can be nonstoichiometric (Kim et al., 2001), and it is indeed possible that oxygen vacancies are present at boundaries or in the bulk. However, is this the only possible interpretation? We show that for the thicknesses considered a better match to the images is obtained using a simple model of surface damage in which atoms are removed from the surface, which would usually be interpreted as surface damage or local thickness variation (from ion milling, for example).
Original languageEnglish
Pages (from-to)111-115
Number of pages5
JournalMicroscopy and Microanalysis
Volume11
Issue number2
DOIs
Publication statusPublished - 1 Apr 2005
Externally publishedYes

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