Anisotropic Local Correlations and Dynamics in a Relaxor Ferroelectric

Abstract

Relaxor ferroelectrics have been a focus of intense attention due to their anomalous dielectric characteristics, diffuse phase transitions, and strong piezoelectricity. Understanding the structure and dynamics of relaxors has been one of the long-standing challenges in solid-state physics, with the current model of polar nanoregions in a non-polar matrix providing only a qualitative description of the relaxor phase transitions. In this paper, we investigate the local structure and dynamics in 75%PbMg${}_{1/3}$Nb${}_{2/3}$O${}_3$-25%PbTiO${}_3$ (PMN-PT) using molecular dynamics simulations and the dynamic pair distribution function technique. We show for the first time that relaxor transitions can be described by local order parameters. We find that structurally, the relaxor phase is characterized by the presence of highly anisotropic correlations between the local cation displacements. These correlations resemble the hydrogen bond network in water. Our findings contradict the current polar nanoregion model; instead, we suggest a new model of a homogeneous random network of anisotropically coupled dipoles.

We combine our manuscript and supplementary information in one file. 5 pages and 3 figures in main text. 3 pages and 3 figures in supplementary information

References in corpus (4)

• Giant electrocaloric effect in the thin film relaxor ferroelectric 0.9 PbMg_(1/3)Nb_(2/3)O_3 - 0.1 PbTiO_3 near room temperature
• Vogel-Fulcher freezing in relaxor ferroelectrics
• Finite-Temperature Properties of Ba(Zr,Ti)O${}_3$ Relaxors From First Principles
• Dielectric relaxation and polar phonon softening in relaxor ferroelectric PbMg_(1/3)Ta_(2/3)O_3

Cited by in corpus (13)

• Reinterpretation of bond-valence model with bond-order formalism: an improved bond-valence based interatomic potential for PbTiO${}_3$
• Origin of Stationary Domain Wall Enhanced Ferroelectric Susceptibility
• Random Electric Field Instabilities of Relaxor Ferroelectrics
• Paraelectric and Ferroelectric States in a Model for Relaxor Ferroelectrics
• First-principles studies of the local structure and relaxor behavior of Pb(Mg${}_{1/3}$Nb${}_{2/3}$)O${}_3$-PbTiO${}_3$-derived ferroelectric perovskite solid solutions
• Condensation of the atomic relaxation vibrations in lead-magnesium-niobate at $T=T^{\ast }$
• Sr-induced dipole scatter in BST: Insights from MD simulations using a transferable bond valence-based interatomic potential
• Terahertz dielectric response and coupled dynamics of ferroelectrics and multiferroics from effective Hamiltonian simulations
• Structure Factor of a Relaxor Ferroelectric
• Relaxation of dynamically disordered tetragonal platelets in the relaxor ferroelectric $0.964{\mathrm{Na}}_{1/2}{\mathrm{Bi}}_{1/2}{\mathrm{TiO}}_3-0.036{\mathrm{BaTiO}}_3$
• Anelastic relaxor behavior of Pb(Mg1/3Nb2/3)O3
• Phase transition of chemically doped uniaxial relaxor ferroelectric
• Sb-5s lone pair dynamics and collinear magnetic ordering in Ba2FeSbSe5