Elastic anomalies associated with transformation sequences in perovskites: I. Strontium zirconate, SrZrO <sub>3</sub>

McKnight, Ruth E. A. and Howard, C. J. and Carpenter, M. A. (2009) Elastic anomalies associated with transformation sequences in perovskites: I. Strontium zirconate, SrZrO <sub>3</sub>. Journal of Physics: Condensed Matter, 21 (1). 015901. DOI 10.1088/0953-8984/21/1/015901

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Official URL: http://iopscience.iop.org/0953-8984/21/1/015901

Abstract

Elastic behaviour associated with the hierarchy of tilting transitions in SrZrO3 has been examined using resonant ultrasound spectroscopy on a ceramic sample at temperatures between 153 and 1531 K. Changes in slope of the evolution of resonance frequencies with temperature indicate that phase transitions occur at 1038 K (Pnma \leftrightarrow Imma ), 1122 K (Imma \leftrightarrow I4/mcm ), and 1367 K (I4/mcm \leftrightarrow Pm\bar {3}m ). Strain analysis of previously recorded neutron diffraction data shows that the I4/mcm \leftrightarrow Pm\bar {3}m and Pnma \leftrightarrow Imma transitions are close to tricritical in character, and that Imma \leftrightarrow I4/mcm is first order. Deviations from the form of the elastic behaviour predicted by Landau theory are found. In particular, elastic softening in the vicinity of the Imma \leftrightarrow I4/mcm transition suggests that local dynamical fluctuations between individual tilt systems occur, rather than a discontinuous switch from one phase to another. Determinations of the mechanical quality factor, Q, show that SrZrO3 in the Pm\bar {3}m phase is a classically high-Q (i.e. non-dissipating) cubic material. I4/mcm and Imma phases both have much greater dissipation (low Q), which is tentatively attributed to the mobility of twin walls. The room temperature Pnma phase is unexpectedly much stiffer than both I4/mcm and Imma phases and has high Q. It appears that when two separate tilt systems operate, as in Pnma, they can interact to reduce strain/order parameter relaxations.

Item Type: Article
Uncontrolled Keywords: 09AREP; IA58;
Subjects: 03 - Mineral Sciences
Divisions: 03 - Mineral Sciences
Journal or Publication Title: Journal of Physics: Condensed Matter
Volume: 21
Page Range: 015901
Identification Number: 10.1088/0953-8984/21/1/015901
Depositing User: Sarah Humbert
Date Deposited: 30 Apr 2010 14:27
Last Modified: 23 Jul 2013 09:57
URI: http://eprints.esc.cam.ac.uk/id/eprint/1374

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