Local structural disorder and its influence on the average global structure and polar properties in Na0.5Bi0.5TiO3

Rao, Badari Narayana and Datta, Ranjan and Chandrashekaran, Selva S and Mishra, Dileep K and Sathe, Vasant and Senyshyn, Anatoliy and Ranjan, Rajeev (2013) Local structural disorder and its influence on the average global structure and polar properties in Na0.5Bi0.5TiO3. In: PHYSICAL REVIEW B, 88 (22).

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Abstract

Na0.5Bi0.5TiO3 (NBT) and its derivatives have prompted a great surge in interest owing to their potential as lead-free piezoelectrics. In spite of five decades since its discovery, there is still a lack of clarity on crucial issues such as the origin of significant dielectric relaxation at room temperature, structural factors influencing its depoling, and the status of the recently proposed monoclinic (Cc) structure vis-a-vis the nanosized structural heterogeneities. In this work, these issues are resolved by comparative analysis of local and global structures on poled and unpoled NBT specimens using electron, x-ray, and neutron diffraction in conjunction with first-principles calculation, dielectric, ferroelectric, and piezoelectric measurements. The reported global monoclinic (Cc) distortion is shown not to correspond to the thermodynamic equilibrium state at room temperature. The global monocliniclike appearance rather owes its origin to the presence of local structural and strain heterogeneities. Poling removes the structural inhomogeneities and establishes a long-range rhombohedral distortion. In the process the system gets irreversibly transformed from a nonergodic relaxor to a normal ferroelectric state. The thermal depoling is shown to be associated with the onset of incompatible in-phase tilted octahedral regions in the field-stabilized long range rhombohedral distortion.

Item Type:	Journal Article
Publication:	PHYSICAL REVIEW B
Publisher:	AMER PHYSICAL SOC
Additional Information:	Copyright for this article belongs to the AMER PHYSICAL SOC
Department/Centre:	Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited:	29 Jan 2014 07:34
Last Modified:	29 Jan 2014 07:35
URI:	http://eprints.iisc.ac.in/id/eprint/48211

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