A new series of complex perovskites La1-xSrxCr1-xTixO3:: Structural characterization

A new series of complex perovskite-type compounds La1-xSrxCr1-xTixO3 involving substitutions at both A and B sites was prepared by the ceramic technique (final heating at 1350 degrees C), X-ray powder diffraction and profile-refinement study of this series show it to comprise orthorhombic perovskites (Pbnm, a approximate to b approximate to root 2a(p), c approximate to root 2a(p), Z = 4) in the range 0 less than or equal to x less than or equal to 0.7 and tetragonal perovskites (I4/mcm, a approximate to root 2a(p), c approximate to 2a(p), Z = 4) in the range 0.8 less than or equal to x less than or equal to 0.9. The tetragonal to cubic phase transition occurs between x = 0.9 and 1.0. Cation ordering is not observed in this solid solution series. The structures of the orthorhombic and tetragonal members are derived from the cubic aristotype by rotation of (Cr,Ti)O-6 octahedra. In contrast to most Pbnm-type perovskites, the orthorhombic compounds in the series La1-xSrxCr1-xTixO3 have a > b, possibly resulting from distortion of the octahedra. (C) 1999 Academic Press.