The generalized Vogel-Fulcher-Tamman equation for describing the dynamics of relaxor ferroelectrics
Levit, Rafael (Universitat Politècnica de Catalunya. Departament de Física)
Martinez-Garcia, Julio C. (Universitat Autònoma de Barcelona. Departament de Física)
Ochoa, Diego A. (Universitat Politècnica de Catalunya. Departament de Física)
Garcia, Jose E. (Universitat Politècnica de Catalunya. Departament de Física)

Date:	2019
Abstract:	Relaxor ferroelectrics (RF) are outstanding materials owing to their extraordinary dielectric, electromechanical, and electro-optical properties. Although their massive applications, they remain to be one of the most puzzling solid-state materials because understanding their structural local order and relaxation dynamics is being a long-term challenge in materials science. The so-called Vogel-Fulcher-Tamman (VFT) relation has been extensively used to parameterize the relaxation dynamics in RF, although no microscopic description has been firmly established for such empirical relation. Here, we show that VFT equation is not always a proper approach for describing the dielectric relaxation in RF. Based on the Adam-Gibbs model and the Grüneisen temperature index, a more general equation to disentangle the relaxation kinetic is proposed. This approach allows to a new formulation for the configurational entropy leading to a local structural heterogeneity related order parameter for RF. A new pathway to disentangle relaxation phenomena in other relaxor ferroics could have opened.
Rights:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan es reconegui l'autoria de l'obra original.
Language:	Anglès
Document:	Article ; recerca ; Versió publicada
Subject:	Ferroelectrics and multiferroics ; Materials for devices
Published in:	Scientific reports, Vol. 9 (August 2019) , art. 12390, ISSN 2045-2322

DOI: 10.1038/s41598-019-48864-0
PMID: 31455803

8 p, 1.5 MB

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