High temperature orbital, charge and structural phase transitions in the cation ordered manganites TbBaMn2O6 and YBaMn2O6.

Williams, A. J. and Attfield, J. P. and Redfern, S. A. T. (2005) High temperature orbital, charge and structural phase transitions in the cation ordered manganites TbBaMn2O6 and YBaMn2O6. Physical Review B, 72. p. 184426. DOI 10.1103/PhysRevB.72.184426

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Abstract

The high-temperature structures and phase transitions of the cation-ordered manganite perovskites TbBaMn2O6 and YBaMn2O6 have been studied by powder neutron diffraction and differential scanning calorimetry. TbBaMn2O6 undergoes an unprecedented transition from a charge and antiferro-orbitally ordered phase to a charge and ferro-orbitally ordered structure at 94.5 °C, and the charge and orbital ordering melts at 200 °C. An orthorhombic Cmmm phase with rotational order of MnO6 octahedra is observed above the transition, and at 514 °C this transforms to the aristotype tetragonal P4/mmm arrangement. YBaMn2O6 is charge and ferro-orbitally ordered up to 225 °C. Above this charge ordering transition, a C2/m phase with two rotational orders is found. This transforms to the Cmmm structure at 437 °C. Discontinuities in volume and volume expansion, and a limited phase coexistence region are observed at the charge ordering transitions, whereas the other transitions are continuous.

Item Type: Article
Uncontrolled Keywords: 2005 AREP 2005 P IA49
Subjects: 03 - Mineral Sciences
Divisions: 03 - Mineral Sciences
Journal or Publication Title: Physical Review B
Volume: 72
Page Range: p. 184426
Identification Number: 10.1103/PhysRevB.72.184426
Depositing User: Sarah Humbert
Date Deposited: 12 Aug 2010 12:56
Last Modified: 23 Jul 2013 10:00
URI: http://eprints.esc.cam.ac.uk/id/eprint/1879

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