Piezoelectricity of SrTiO3: an ab initio description.
Résumé
The complete piezoelectric tensor of ferroelectric SrTiO3 at low temp. is computed by ab initio theor. simulations. Both direct and converse-coupled with elastic compliance-piezoelectricity are computed and interpreted in terms of electronic and nuclear contributions. The role of the ferroelec. soft phonon mode on this property is found to be dramatic thus leading to a possible giant piezoelec. response at very low temperature. Two possible space groups are considered for the ferroelec. phase of SrTiO3, both compatible with the available exptl. data: a tetragonal I4cm and an orthorhombic Ima2 one. The piezoelectric response of the two symmetries is predicted to be rather different and could be experimentaly detected to clarify the (still unknown) structure of the ferroelectric phase of SrTiO3.