A New Series of Complex Perovskites La1-xSrxCr1-xTixO3: Structural Characterization

A new series of complex perovskite-type compounds La1-xSrxCr1-xTixO3involving substitutions at bothAandBsites was prepared by the ceramic technique (final heating at 1350°C). X-ray powder diffraction and profile-refinement study of this series show it to comprise orthorhombic perovskites (Pbnm,a`b` ap,c` ap,Z=4) in the range 0,x,0.7 and tetragonal perovskites (I4/mcm,a` ap,c`2ap,Z=4) in the range 0.8,x,0.9. The tetragonal to cubic phase transition occurs betweenx=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)O6octahedra. In contrast to mostPbnm-type perovskites, the orthorhombic compounds in the series La1-xSrxCr1-xTixO3havea>b, possibly resulting from distortion of the octahedra.