Abstract
Structure-property relationships in ferroelectrics extend over several length scales from the individual unit cell to the macroscopic device, and with dynamics spanning a broad temporal domain. Characterizing the multi-scale structural origin of electric field-induced polarization reversal and strain in ferroelectrics is an ongoing challenge that so far has obscured its fundamental behaviour. By utilizing small intensity differences between Friedel pairs due to resonant scattering, we demonstrate a time-resolved X-ray diffraction technique for directly and simultaneously measuring both lattice strain and, for the first time, polarization reversal during in-situ electrical perturbation. This technique is demonstrated for BaTiO3-BiZn0.5Ti0.5O3 (BT-BZT) polycrystalline ferroelectrics, a prototypical lead-free piezoelectric with an ambiguous switching mechanism. This combines the benefits of spectroscopic and diffraction-based measurements into a single and robust technique with time resolution down to the ns scale, opening a new door to in-situ structure-property characterization that probes the full extent of the ferroelectric behaviour.
Highlights
The presence of a strong and rapidly applied electric field, these mechanisms may be suppressed in favour of an entirely homogeneous switching[9]
We present an example of the use of resonant synchrotron X-ray diffraction to directly and simultaneously measure the dynamic strain and, for the first time, the ionic response of a polycrystalline ferroelectric to cyclic electric fields. We demonstrate this approach using a high-energy (30 keV) X-ray beam on a material in which differentiating between multiple polarization reversal mechanisms remains a significant challenge: tetragonal 0.94·BaTiO3-0.06·BiZn0.5Ti0.5O3 (BT-BZT) perovskite-based polycrystalline ferroelectrics[30]
We have shown it is possible to measure the Friedel’s pair contrast by high-energy X-rays using powder diffraction
Summary
The presence of a strong and rapidly applied electric field, these mechanisms may be suppressed in favour of an entirely homogeneous switching[9]. Overlapping hkl and hkl Debye-Scherrer rings means measuring such Friedel pair contrast using powder diffraction has never been considered, despite the fact that the crystallographic structure of their powder crystallites can be actively inverted by an external electric field in the same manner as single crystals. This inversion provides the opportunity to observe the Friedel pair contrast by the application of an electric field
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