JAHN-TELLER DISTORTED PEROVSKITES

The Jahn-Teller Distortion and Cation Ordering in the Perovskite Sr2MnSbO6
M Cheah, P J Saines and B J Kennedy
J Solid State Chem 179, 1775-1781 (2006)

The perovskite Sr2MnSbO6 has been synthesized using conventional ceramic techniques and structurally characterized using high-resolution powder X-ray and neutron diffraction. The structure is tetragonal in space group I4/m. The octahedra were found to feature Jahn–Teller (JT) distortion due to the presence of Mn3+, and this is identified as strongly contributing to the octahedral tilting. Evidence for B-site cation ordering is presented however there is extensive anti-site disorder. The disordering of the Mn3+ and Sb5+ cations is believed to be a result of the similar size of these two cations and the polarizability of the Sb5+ cation. The structure was found to undergo a transition to cubic symmetry at 521 °C with removal of the octahedral tilting leading to the quenching of the JT distortion. This phase transition was found to be continuous and tricritical in nature.

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