Negative‐Pressure‐Induced Large Polarization in Nanosized PbTiO<sub>3</sub>
Jing Sun, Qiang Li, He Zhu, Zhanning Liu, Kun Lin, Na Wang, Qinghua Zhang, Lin Gu, Jinxia Deng, Jun Chen, Xianran Xing
Abstract
Abstract Ferroelectric materials usually undergo decay with particle size decreasing into the nanoscale. At the critical value, the crystal structure undergoes a transition from the ferroelectric to paraelectric phase and the ferroelectricity vanishes. It is a big issue to sufficiently maintain strong ferroelectricity at the nanoscale. Herein, it is reported that synthesized 0D freestanding PbTiO 3 nanoparticles (NPs) present negative pressure along the c axis (Δ c / c bulk × 100% = −2.406), inducing large spontaneous polarization P S (71.2 µC cm −2 in 12 nm). Further local structural studies by atomic pair distribution functions and extended X‐ray absorption fine structure indicate the structural evolution of nanosized PbTiO 3 . High‐angle annular dark‐field STEM images reveal the existence of preponderant PbO‐terminations on the surface of the PbTiO 3 NPs. Ab initio calculation reveals the enhanced hybridization between Pb and O ions, which gives rise to the negative pressure and tensile stress to stabilize the high tetragonality and large polarization. The present work demonstrates an untraditional route to enhance the ferroelectricity and related properties in functional nanostructured materials, being of significance to nanodevices.