Structural characterisation of the perovskite series Sr0.9−xCaxCe0.1MnO3: Influence of the Jahn–Teller effect

Fifteen perovskite-type compounds Sr0.9−xCaxCe0.1MnO3, x=0–0.9 in steps as fine as 0.05, have been synthesised by solid state methods, and the room temperature structures characterised using X-ray synchrotron powder diffraction. At low Ca contents (x⩽0.45) the structures are tetragonal in space group I4/mcm and at high Ca contents (x⩾0.55) the compounds are orthorhombic in space group Pbnm. At room temperature these two phases co-exist in the compound with x=0.5. XANES measurements show the Ce to be present as Ce4+ in all the oxides. High temperature structures are reported for selected members.

At room temperature the oxides with x⩽0.45 in the series Sr0.9-xCaxCe0.1MnO3 are tetragonal in I4/mcm with a large Jahn–Teller distortion, and those with x⩾0.55 are orthorhombic, in Pbnm. Heating the tetragonal samples results in two transitions, ultimately the structure becomes cubic.Figure optionsDownload as PowerPoint slide