Structures and phase transition in the layered perovskite La0.6Sr0.1TiO3:: a new orthorhombic structure solved from high-resolution diffraction in combination with group theoretical analysis

The crystal structure of the layered perovskite La0.6Sr0.1TiO3 at room temperature has been solved by synchrotron x-ray powder diffraction in combination with group theoretical analysis. The structure is orthorhombic in Cmmm, on a cell with a = 7.7556(l), b = 7.7349(l) and c = 7.7910(l) Angstrom. It is believed that this is also the structure adopted by La2/3TiO3. Pertinent features are the alternation of fully and partly occupied layers of La (Sr) cations, and out-of-phase tilting of the TiO6 octahedra around an axis perpendicular to the direction of the cation ordering. The compound undergoes a second order transition to a tetragonal structure, the transition temperature being estimated as 360degreesC.