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

A new series of complex perovskite-type compounds La1-xSrxCr1-xTixO3 involv ing substitutions at both A and B sites was prepared by the ceramic techniq ue (final heating at 1350 degrees C), X-ray powder diffraction and profile- refinement study of this series show it to comprise orthorhombic perovskite s (Pbnm, a approximate to b approximate to root 2a(p), c approximate to roo t 2a(p), Z = 4) in the range 0 less than or equal to x less than or equal t o 0.7 and tetragonal perovskites (I4/mcm, a approximate to root 2a(p), c ap proximate to 2a(p), Z = 4) in the range 0.8 less than or equal to x less th an 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 se ries. 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 La 1-xSrxCr1-xTixO3 have a > b, possibly resulting from distortion of the octa hedra. (C) 1999 Academic Press.