First-principles Structural Stability in the Strontium-Titanium-Oxygen system

International audience; First principles calculations have been made to theoretically interpret the structural stability of SrTiO3 as a function of pressure or strain. We show that the orthorhombic Pbnm structure is more stable than the ideal perovskite one due to rotations of TiO6 octahedra at high pressures or deformations of TiO6 octahedra at low pressures. Such a study is extended to the structural stability of the Ruddlesden-Popper Srn+1TinO3n+1 phases for n=1, 2 and 3, in which the lattice constraints are induced by the intercalation of SrO layers in the perovskite structure.