Characterizing oxygen atoms in perovskite and pyrochlore oxides using ADF-STEM at a resolution of a few tens of picometers
Abstract
We present an aberration corrected scanning transmission electron microscopy (ac-STEM) analysis of 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 a method by which light atoms can be resolved in the quantitative ADF-STEM images. Using this method, we resolved oxygen atoms in perovskite and pyrochlore oxides and propose this method to be suitable for other materials containing both light and heavy elements.
- Publication:
-
Acta Materialia
- Pub Date:
- April 2021
- DOI:
- 10.1016/j.actamat.2021.116717
- arXiv:
- arXiv:2009.10037
- Bibcode:
- 2021AcMat.20816717M
- Keywords:
-
- STEM;
- Vacancies;
- Point defects;
- Perovskite;
- Pyrochlore;
- Condensed Matter - Materials Science
- E-Print:
- 18 pages and 7 figures plus supplementary information