Effects of an external electric field and crack-like defects on the ferroelectric polarisation of PbTiO3

Abstract

This study employs atomic structure optimisation based on the core-shell model to investigate the dependence of electric polarisation in PbTiO₃ (PTO) on external electric fields and the presence of defects. The results reveal the relationship between polarisation (P) and electric field (E), as illustrated by the hysteresis loop, with characteristic parameters including the coercive field E_c=±0.115 eV/Å, the remanent polarisation P_r=±86,8 µC/cm², and the saturation polarisation P_s=±101,21 µC/cm². The presence of cracks leads to a reduction in P_r by 34.9, 40.2, and 31.2% for crack sizes of a×c, a×2c, and 2a×c, respectively, while Ec decreases by 21.7% (a×c) and 18.3% (a×2c), but increases by 16.5% in the case of 2a×c. Additionally, the stress at E_c drops by 40.6% (from 7.2 to 4.28 GPa), indicating structural disruption. These findings not only elucidate the polarisation mechanism of PTO but also provide an important theoretical basis for optimising ferroelectric device design, particularly ferroelectric random access memories (FeRAM), sensors, and high-precision electronic control systems. The study also suggests future research directions for investigating the interaction between structural defects and external electric fields in ferroelectric materials.