Powder Diffraction Studies of Phase Transitions in Manganese Perovskites


The results of recent structural studies of some Manganese perovskites are presented, in particular oxides in
the system Cal_xSrxMn03 and SrRllo.sMno.503' In the fIrst series we fIrstly show the power of synchrotron X-ray powder
diffraction to refme accurate and precise structures for oxides containing fIrst row transition metals and then show the
presence of a direct orthorhombic Pbnm to tetragonal 14/mcm transition associated with the tilting of the Mn06
octahedra. The inclusion of a heavier second row transition metal reduces the precision of the structure, however the
details of the tetmgonal to cubic phase transition in SrRllo.sMno.503 are still established.
Keywords: Perovskite, Phase Transition, Synchrotron X-ray Powder Diffraction, Jahn- Teller Distortion. B. J. Kennedy
School of Chemistry, The University of Sydney, Sydney, NSW 2006 Australia