Disruption of polar order in lead zirconate titanate by composition-modulated artificial superlattice

Lead zirconate titanate (Pb (Zr x , Ti 1− x )O 3 : PZT) is a well-known ferroelectric compound, in which long-range polar order is usually developed. In the present study, it was clarified by distortion-corrected atomic-scale scanning transmission electron microscopy imaging that long-range polar order is disrupted in PZT by utilizing composition-modulated superlattice. Shape of unit cell was unusual both in the Pb(Zr 0.65 Ti 0.35 )O 3 (PZT65) and Pb(Zr 0.30 Ti 0.70 )O 3 (PZT30) layers, which was due to mutual in-plane lattice constraint. By taking account of this, first-principles calculations clarified that multiple directions can be energetically favorable for lead-ion displacement, which explains a reason why long-range polar order was disrupted.