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Structural transformations and physical properties of (1-x) Na0.5Bi0.5TiO3 - x BaTiO3 solid solutions near a morphotropic phase boundary

Mohanty, Hari Sankar and Dam, Tapabrata and Borkar, Hitesh and Pradhan, Dhiren K and Mishra, K K and Kumar, Ashok and Sahoo, Balaram and Kulriya, Pawan K and Cazorla, C and Scott, J F and Pradhan, Dillip K (2019) Structural transformations and physical properties of (1-x) Na0.5Bi0.5TiO3 - x BaTiO3 solid solutions near a morphotropic phase boundary. In: JOURNAL OF PHYSICS-CONDENSED MATTER, 31 (7).

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Official URL: https://doi.org/10.1088/1361-648X/aaf405

Abstract

Piezoelectric and other physical properties are significantly enhanced at (or near) a morphotropic phase boundary (MPB) in ferroelectrics. MPB materials have attracted significant attention owing to both fundamental physics as well as the possibility of well-regulated energy and information storage devices which are dominated by lead (Pb)-based materials. Here, we report the crystal structure, Raman spectra, dielectric constant and polarization near the MPB of lead free (1 - x) Na0.5Bi0.5TiO3 - x BaTiO3 (0.00 <= x <= 0.10) solid-solution, prepared by sol-gel auto combustion technique and sintered by microwave sintering technique. With the addition of BaTiO3 into Na0.5Bi0.5TiO3, it induces a structural phase transition from R3c (a single phase) to R3c + P4mm (a dual phase) close to x = 0.06 and 0.07 and transform to a high symmetry tetragonal phase P4mm at higher compositions (x = 0.08 to 0.10) as evident from our x-ray Rietveld refinement and Raman spectroscopic results. We perform first-principles calculations based on density functional theory that confirm a structural transition from a rhombohedral to a tetragonal phase under increasing x. In the prepared solid solution, an anomalous enhancement of remnant polarization (2P(r)(0)) was observed for x = 0.06 and 0.07, which has been explained based on the existence of the MPB. On the other hand, the value of coercive field E-C(0) was found to be decreased linearly from x = 0.00 to 0.06; it is constant for higher compositions. Further details of the ferroelectric properties on the electric field poled samples have been studied and compared with the as-grown (unpoled) samples.

Item Type: Journal Article
Additional Information: Copyright of this article belongs to IOP PUBLISHING LTD
Keywords: lead-free ferroelectric materials; NBT-BT solid solution; morphotropic phase boundary; first-principles calculations; microwave sintering; crystal structure
Department/Centre: Division of Chemical Sciences > Materials Research Centre
Depositing User: Id for Latest eprints
Date Deposited: 28 Jan 2019 08:53
Last Modified: 28 Jan 2019 08:53
URI: http://eprints.iisc.ac.in/id/eprint/61471

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