Structural characterisation of the perovskite series SrxCa1-x-yNdyMnO3: Influence of the Jahn-Teller effect

Journal article

The crystal structures of the perovskite manganites SrxCa1-x-yNdyMnO3 with y=0.1 or 0.2 have been investigated using synchrotron X-ray powder diffraction. At room temperature the structures change from Pm over(3, -) m ↔ I 4 / mcm ↔ Pbnm depending on the cation distribution, the different structures exhibiting different tilts of the MnO6 octahedra. High temperature diffraction measurements demonstrate the presence of, an apparently continuous, isosymmetric I4/mcm to I4/mcm phase transition associated with the removal of long range orbital ordering. Heating the manganites to still higher temperatures results in a continuous transition to the cubic Pm over(3, -) m structure. A feature of such transitions is the continuous evolution of the octahedral tilt angle through the I4/mcm to I4/mcm phase transition. The orthorhombic structures do not exhibit orbital ordering and although a first order transition to the tetragonal structure is observed in Sr0.4Ca0.5Nd0.1MnO3, this high temperature tetragonal structure does not exhibit orbital ordering. © 2009 Elsevier Inc. All rights reserved.

Authors: Kennedy, B; Saines, P; Ting, J; Zhou, Q; Kimpton, J

• Journal: Journal of Solid State Chemistry
• Volume: 182
• Issue: 10
• Pages: 2858-2866
• Publication date: 2009-10-01
• DOI: 10.1016/j.jssc.2009.07.041
• EISSN: 1095-726X
• ISSN: 0022-4596
• Language: English
• Keywords: Structural phase transition; Perovskite; Manganites; Isosymmetric phase transition