New phase transitions in ceramic SrSnO3: Raman scattering analysis and differential thermal analysis

Singh, M. K. and Karan, N. K. and Katiyar, R. S. and Scott, J. F. and Jang, H. M. (2008) New phase transitions in ceramic SrSnO3: Raman scattering analysis and differential thermal analysis. Journal of Physics: Condensed Matter, 20 (5). 055210. DOI 10.1088/0953-8984/20/5/055210

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Official URL: http://dx.doi.org/10.1088/0953-8984/20/5/055210

Abstract

We report a continuous or nearly continuous order–disorder transition from orthorhombic (pseudo-tetragonal) to orthorhombic structure on heating in SrSnO3 at 377 ◦C, and a discontinuous transition near 260 ◦C. The transition at 377 ◦C is manifested in an order of magnitude increase in Raman linewidths and in a λ-shaped anomaly in the specific heat. Previous work (Mountstevens et al 2005 Phys. Rev. B 71 220102R) has interpreted the Pnma–Imma transition at 636 ◦C as a continuous order–disorder transition and emphasized that this would be unique for an octahedron-tilting transition in oxide perovskite, as they have always been found to be displacive (‘Glazer’s rule’). Our work on Raman scattering and differential thermal analysis shows that the disorder sets in at much lower temperature 377 ◦C, so that the 636 ◦C transition is a disorder–disorder or a displacive transition within an already highly disordered structure. Hence it may not be as unusual as had been claimed, and Glazer’s rule remains inviolate.

Item Type: Article
Uncontrolled Keywords: 2007 AREP IA55 2008 P
Subjects: 03 - Mineral Sciences
Divisions: 03 - Mineral Sciences
Journal or Publication Title: Journal of Physics: Condensed Matter
Volume: 20
Page Range: 055210
Identification Number: 10.1088/0953-8984/20/5/055210
Depositing User: Sarah Humbert
Date Deposited: 16 Feb 2009 13:03
Last Modified: 23 Jul 2013 10:08
URI: http://eprints.esc.cam.ac.uk/id/eprint/690

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