First-principles study of ferroelectric and piezoelectric properties of tetragonal SrTiO_3 and BaTiO_3 with in-plane compressive structures

摘要

Ferroelectric and piezoelectric properties of tetragonal SrTiO_3 and BaTiO_3 with in-plane compressive structures have been investigated using a first-principles calculation. It has been found that the ferroelectric structure appears even in SrTiO_3 with in-plane compressive structures. The piezoelectric constant e33 drastically increases in SrTiO_3 rather than that in BaTiO_3 as the tetragonal ratio ca (>1) is close to 1. On the other hand, e31 shows negative in SrTiO _3 while positive in BaTiO_3, although the changes in their absolute values are very small. We have found that these properties of e33 and e31 in SrTiO_3 and BaTiO_3 are closely related to the ionic distances.