Pressure-induced phase transition(s) in KMnF 3 and the importance of the excess volume for phase transitions in perovskite structures.

Guennou, Mael and Bouvier, Pierre and Garbarino, Gaston and Kreisel, Jens and Salje, Ekhard K. H. (2011) Pressure-induced phase transition(s) in KMnF 3 and the importance of the excess volume for phase transitions in perovskite structures. Journal of Physics: Condensed Matter, 23 (48). p. 485901. DOI 10.1088/0953-8984/23/48/485901

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Abstract

We report a pressure-dependent investigation of KMnF3 by x-ray diffraction up to 30 GPa. The results are discussed in the framework of Landau theory and in relation to the isostructural phase transition in SrTiO3. The phase transition temperature near 186 K in KMnF3 shifts to room temperature at a critical pressure of Pc = 3.4 GPa; the pressure dependence of the transition point follows ΔPc/ΔTc = 0.0315 GPa K−1. The transition becomes second order under high pressure, close to the tricritical point. The phase transition is determined by the rotation of MnF6 octahedra with their simultaneous expansion along the rotation axis. The rotation angle was found to increase to 10.5° at 24 GPa. An additional anomaly was observed at higher pressure around 25 GPa, suggesting a further phase transition.

Item Type:	Article
Uncontrolled Keywords:	2011AREP;IA63;
Subjects:	03 - Mineral Sciences
Divisions:	03 - Mineral Sciences
Journal or Publication Title:	Journal of Physics: Condensed Matter
Volume:	23
Page Range:	p. 485901
Identification Number:	10.1088/0953-8984/23/48/485901
Depositing User:	Sarah Humbert
Date Deposited:	06 Feb 2012 16:18
Last Modified:	23 Jul 2013 10:03
URI:	http://eprints.esc.cam.ac.uk/id/eprint/2354

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