Nanopore-induced dielectric and piezoelectric enhancement in PbTiO₃ nanowires

Porous tetragonal PbTiO₃ nanowires, synthesized through an intermediate pre-perovskite structure, exhibit distinct behaviors from those of the corresponding bulk PbTiO₃. Here we investigate the role of nanopores in the ferroelectric, dielectric, and piezoelectric properties of ferroelectric PbTiO₃ nanowires employing phase-field simulations. It is found that the presence of pores gives rise to large enhancements in both dielectric constant and piezoelectric coefficient by ~50% and 30%, respectively, compared with those of the bulk PbTiO₃. It is shown that the smaller the pore size is, the higher the dielectric and piezoelectric responses of the nanowire are. A charge compensation mechanism is proposed to explain the experimentally measured change of oxygen ions concentration at the pore surfaces. The findings provide in-depth insights into modulation of material properties through nanopores.