Effect of strain and oxygen vacancies on the structure of 180o ferroelectric domain walls in PbTiO3
Abstract
In this paper we study the effect of normal and shear strains and oxygen vacancies on the structure of 180o ferroelectric domain walls in PbTiO3. It is known that oxygen vacancies move to the domain walls and pin them. Hence, we assume a periodic arrangement of oxygen vacancies on both Pb-centered and Ti-centered domain walls in PbTiO3. We use a semi-analytic anharmonic lattice statics method for obtaining the relaxed configurations using a shell potential. In agreement with recent ab initio calculations, we observe that a Pb-centered domain wall with oxygen vacancies is not stable even under strain. Our semi-analytic calculations for PbTiO3 show that oxygen vacancies affect the structure of 180o domain walls significantly but do not have a considerable effect on the thickness of domain walls; they broaden the domain walls by about fifty percent. We also study the effect of normal and shear strains on both perfect and defective 180o domain walls. We observe that normal and shear strains affect the structure but do not change the domain wall thickness.