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arXiv · 2009.10037

Characterizing oxygen atoms in perovskite and pyrochlore oxides using ADF-STEM at a resolution of a few tens of picometers

Ali Mostaed·Brant Walkley·Monica Ciomaga Hatnean·Geetha Balakrishnan·Martin R. Lees·Richard Beanland·Derek C. Sinclair·Ian M. Reaney
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Abstract

We present an aberration corrected scanning transmission electron microscopy (ac-STEM) analysis of the perovskite (LaFeO3) and pyrochlore (Yb2Ti2O7 and Pr2Zr2O7) oxides and demonstrate that both the shape and contrast of visible atomic columns in annular dark-field (ADF) images are sensitive to the presence of nearby atoms of low atomic number (e.g. oxygen). We show that point defects (e.g. oxygen vacancies), which are invisible - or difficult to observe due to limited sensitivity - in X-ray and neutron diffraction measurements, are the origin of the complex magnetic ground state of pyrochlore oxides. In addition, we present, for the first time, a method by which light atoms can be resolved in quantitative ADF-STEM images. Using this method, we resolved oxygen atoms in perovskite and pyrochlore oxides.

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Ali Mostaed, Brant Walkley, Monica Ciomaga Hatnean, Geetha Balakrishnan, Martin R. Lees, Richard Beanland, Derek C. Sinclair, Ian M. Reaney. 2020-09-21. Characterizing oxygen atoms in perovskite and pyrochlore oxides using ADF-STEM at a resolution of a few tens of picometers. https://arxiv.org/abs/2009.10037

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