Synchrotron X-ray diffraction study of the Ba1−xSrSnO3 solid solution

At room temperature the sequence of phases with increasing amounts of strontium in the stannate perovskite system Ba1−xSrSnO3 has been established from high resolution synchrotron X-ray powder diffraction. The observed sequence orthorhombic (Pbnm), orthorhombic (Ibmm), tetragonal (I4/mcm), and cubic (Pm3̄m) is a consequence of the sequential introduction of cooperative tilting of the corner sharing SnO6 octahedra. The cell volume changes smoothly across the series with no obvious discontinuities associated with the phase transitions.

Portions of the synchrotron X-ray diffraction profiles (λ=0.82453 Å) from selected Ba1−xSrxSnO3 samples together with the results of fitting by the Rietveld method.Figure optionsDownload as PowerPoint slideHighlights
► Structures of the stannate perovskites Ba1−xSrSnO3 refined from synchrotron XRD.
► The sequence Pm3̄m→I4/mcm→Ibmm→Pbnm results from tilting of the octahedra.
► The tilting maintains optimal bonding of the cations seen from the BVS analysis.