In-situ Bragg coherent X-ray diffraction imaging of polar nanoregions in barium titanate nanocrystals during phase transition

We propose to explore the origin of an interesting stripe strain network we have recently discovered inside ferroelectric barium titanate oxide (BTO) nanocrystals. These strain stripes support the existence of local rhombohedral polar nanoregions (PNRs), not reported in nanocrystals before. We plan to use Bragg coherent X-ray imaging (BCDI) to study the temperature dependence of these PNRs in our sample. The 250nm single crystals are an ideal size and have internal 50nm well-defined strain stripe domains networks which are resolvable by BCDI at ID01. Crystals will be first selected at room temperature, then ramped up in temperature to cross the ferroelectric phase transition at 413K where the PNRs are expected to vanish. The evolution of the PNRs and reversibility of the network formation will thus be tracked in a single nanoparticle. The nanomaterial has potential in ferroelectric memory applications.