Limited by challenges in light-atom imaging, microscopic investigations of ferroelectricity have used cation–cation displacements as a proxy for the true cation–anion distortions. Using electron ptychography, oxygen anions can be tracked to observe an otherwise-hidden ferroelectric mechanism in thin-film NaNbO3, which would have appeared antiferroelectric from cations alone.
- Harikrishnan KP
- Ruijuan Xu
- David A. Muller
