Structural and electronic phase transitions in Sr1−xCexMnO3 perovskites

The structures of eight members of the series Sr1−xCexMnO3 with 0.075⩽x⩽0.4 have been established using synchrotron X-ray powder diffraction. These exhibit the sequence of structurescubicPm3¯m⟶x≈0.08tetragonalI4/mcm⟶x≈0.35orthorhombicImmawith increasing Ce content. Unusual peak broadening due to domain wall scattering is observed near the composition-induced first-order cubic–tetragonal transition. The temperature dependence of the structures for three examples x=0.1, 0.2 and 0.35 is described. For the x=0.1 and 0.35 samples evidence for a first-order loss of the orbital ordering associated with a cooperative Jahn–Teller distortion is presented. The onset of the orbitally disordered state is accompanied by a discontinuous reduction in cell volume.

Graphical abstractThe presence of small amounts of trivalent Mn in the series Sr1−xCexMnO3 has a dramatic effect on the structure, with the structure changing from cubic to tetragonal and finally orthorhombic. The orbital ordering present at room temperature is lost upon heating.Figure optionsDownload full-size imageDownload as PowerPoint slide