Competing structural phase transition scenarios in the giant tetragonality ferroelectric BiFeO3-PbTiO3: Isostructural vs multiphase transition

Kothai, V and Senyshyn, Anatoliy and Ranjan, Rajeev (2013) Competing structural phase transition scenarios in the giant tetragonality ferroelectric BiFeO3-PbTiO3: Isostructural vs multiphase transition. In: JOURNAL OF APPLIED PHYSICS, 113 (8).

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Abstract

A systematic x-ray and neutron powder diffraction study of the giant tetragonality multiferroic (1-x) BiFeO3-(x) PbTiO3 have revealed that the compositions close to the morphotropic phase boundary present two different structural phase transition scenarios on cooling from the cubic phase: (i) cubic -> tetragonal (T-2) + tetragonal (T-1) -> tetragonal (T-1) and (ii) cubic -> tetragonal (T-2) + tetragonal (T-1) + rhombohedral (R3c) -> tetragonal (T-1) + rhombohedral (R3c). The comparatively larger tetragonality (c/a - 1) of the T-1 phase as compared to the coexisting isostructural T-2 phase is shown to be a result of significantly greater degree of overlap of the Pb/Bi-6s and Ti/Fe-3d with the O-2p orbitals as compared to that in the T-2 phase. The formation/suppression of the minor metastable rhombohedral phase seems to be governed by subtle play of local kinetic factors. In the scenario when the minor rhombohedral (R) phase is formed along with the tetragonal phases it is able to accommodate the large transformation stress in the system due to formation of the tetragonal phases, and prevent the solid from disintegration into powder after sintering. When the metastable rhombohedral phase is not formed, the large transformation strain ruptures the grain boundaries leading to fragmentation of the dense solid to powder. (C) 2013 American Institute of Physics. http://dx.doi.org/10.1063/1.4792215]

Item Type:	Journal Article
Publication:	JOURNAL OF APPLIED PHYSICS
Publisher:	AMER INST PHYSICS
Additional Information:	Copyright for this article belongs to the AMER INST PHYSICS, USA.
Department/Centre:	Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited:	26 Apr 2013 11:03
Last Modified:	26 Apr 2013 11:03
URI:	http://eprints.iisc.ac.in/id/eprint/46466

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