Revealing the sequence of switching mechanisms in polycrystalline ferroelectric/ferroelastic materials

Ferroelectric materials find application in numerous electronic devices and are continuously enabling the development of new technologies. Their versatility is intimately related to the unique property to switch the polarization with electric fields. However, the switching mechanisms in polycrystalline ferroelectric materials remain insufficiently understood. Here we reveal that switching in ferroelectric/ferroelastic materials consists of a sequence of individual events, separated into three regimes: rapid movement of non-180 degrees domain walls, main switching phase with 180 degrees and non-180 degrees switching events, and creep-like non-180 degrees domain wall movement. The determination of the mechanisms was enabled by a novel measurement approach, simultaneously tracking the time dynamics of switched polarization, macroscopic strain, and structural changes. Time-resolved in situ synchrotron diffraction allowed direct insight into the non-180 degrees domain wall dynamics and lattice strains and gave evidence for strong time correlation of non-180 degrees switching events in different grains of the polycrystalline material. The obtained results open new opportunities for targeted manipulation of individual switching events and tuning of material's functional properties. (C) 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.