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. (C) 2020 Acta Materialia inc. Published by Elsevier Ltd. All rights reserved.