Ferroelectricity in Pb_1+δZrO₃ Thin Films

Antiferroelectric PbZrO 3 is being considered for a wide range of applications where the competition between centrosymmetric and noncentrosymmetric phases is important to the response. Here, we focus on the epitaxial growth of PbZrO 3 thin films and understanding the chemistry–structure coupling in Pb 1+δ ZrO 3 (δ = 0, 0.1, 0.2). High-quality, single-phase Pb 1+δ ZrO 3 films are synthesized via pulsed-laser deposition. Although no significant lattice parameter change is observed in X-ray studies, electrical characterization reveals that while the PbZrO 3 and Pb 1.1 ZrO 3 heterostructures remain intrinsically antiferroelectric, the Pb 1.2 ZrO 3 heterostructures exhibit a hysteresis loop indicative of ferroelectric response. Further X-ray scattering studies reveal strong quarter-order diffraction peaks in PbZrO 3 and Pb 1.1 ZrO 3 heterostructures indicative of antiferroelectricity, while no such peaks are observed for Pb 1.2 ZrO 3 heterostructures. Density functional theory calculations suggest the large cation nonstoichiometry is accommodated by incorporation of antisite Pb Zr defects, which drive the Pb 1.2 ZrO 3 heterostructures to a ferroelectric phase with R 3 c symmetry. In the end, stabilization of metastable phases in materials via chemical nonstoichiometry and defect engineering enables a novel route to manipulate the energy of the ground state of materials and the corresponding material properties.