Influence of cation ordering on octahedral tilting in perovskites
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Date
2005-11-27
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The Bragg Institute, Australian Nuclear Science and Technology Organisation
Abstract
The compound LaO.6SrO.1Ti03, taken to represent the ideal Lag/3TiO3, adopts a structure in which the A-site layers are alternately fully and partly occupied by the La(Sr)ions. At room temperature the structure also shows a tilting of the TiO5 octahedra around a single axis perpendicular to the layering direction. Quenching the material during preparation can produce a variant in which the cations are disordered on the A-site, offering the opportunity to study the effect of cation ordering on octahedral tilting. Slow-cooled and quenched specimens were studied over a range of temperatures using high-resolution neutron powder diffraction. Inspection of the relevant diffraction peaks confirmed the expected difference in cation ordering. At room temperature, the cell volume was 0.1% less in the ordered sample than in the disordered one. The extent of octahedral tilting was much the same in the two samples, with similar transition temperatures for removal of the tilting. The orthorhombic distortion that accompanied this tilting in the ordered sample was, surprisingly, not evident in the disordered sample——that is the effect of disordering the cations seems to switch off the strain (tilt) order
parameter coupling in this perovskite. © 2005 The Authors
Description
Physical copy held by ANSTO Library at DDC 539.7217/2
Keywords
Lanthanum, Strontium, Titanium, Layers, Ambient temperature, Cations, Neutron diffraction, Perovskite, Strains
Citation
Zhang, Z., Howard, C. J., Carpenter, M. A., & Knight, K. S. (2005). Influence of cation ordering on octahedral tilting in perovskites. Paper presented at the Eighth International Conference on Neutron Scattering ICNS 2005: "Neutrons for structure and dynamics - a new era", Sydney Convention & Exhibition Centre, Sydney, Australia, 27 November-2 December 2005. In Final Programme and Abstract Book, (p. 233).