Mechanical properties and strain behavior of ferroelectric PbTiO3 under hydrostatic pressure: a combined shell–core molecular dynamics study

Understanding the coupling between atomic structure, mechanical response, and ferroelectric behavior is essential for the reliable application of PbTiO3 in miniaturized devices. In this study, a core–shell molecular dynamics approach combined with atomic structure optimization is employed to investigate the mechanical properties, strain behavior, and the influence of hydrostatic pressure on the polarization–electric field hysteresis of PbTiO3. The calculated lattice parameters and elastic constants agree closely with both the present and previously reported first-principles results, with deviations below 1 %, confirming the reliability of the adopted shell-model potential. The calculated elastic constants reveal pronounced elastic anisotropy, with a marked difference between C11= 286.92 GPa and C33 = 99.05 GPa. The bulk modulus (K =100.54 GPa) and shear modulus (G = 56.193 GPa) indicate effective resistance to volumetric and shear deformation. Stress–strain analysis further demonstrates a high stress-bearing capability under multiaxial loading, with the shear stress σxy reaching 28.76 GPa at a shear strain of 24 % in the crystallographic plane. In addition, hydrostatic pressure is shown to significantly modify the P-E hysteresis characteristics, highlighting its critical role in regulating ferroelectric switching behavior. These results clarify the structure–property relationships governing the mechanical and ferroelectric responses of PbTiO3, providing useful insights for ferroelectric and microelectromechanical devices operating under high-stress and high-pressure conditions.