Cation disorder in Sr0.67Ba0.33Nb2O6 assessed by aberration corrected stem
Résumé
The microstructure and composition of a single crystal of the relaxor Sr0.67Ba0.33Nb2O6 have been assessed by aberration corrected TEM. Electron diffraction showed the presence of diffuse intensity and superstructure incommensurate reflections, compatible with Sr vacancies and Sr/Ba mixing at specific crystal sites respectively. Atomic resolution high angle annular dark field imaging confirmed the presence of these cation vacancies and electron energy loss spectroscopy demonstrated the random mixing of Ba and Sr. Unveiling structure and chemistry with this unprecedent spatial resolution gives the necessary understanding of the electric charge disorder at the origin of polar nanodomains, ultimately leading to relaxor behaviour.