Polarization behavior in a compositionally graded relaxor-ferroelectric crystal visualized by angle-resolved polarized Raman mapping

Explaining the properties and functions of materials in terms of their atomic arrangements and inhomogeneous structures is a fundamental challenge for the development of ferroelectric oxides. Dielectric response, a fundamental property of matter, can be explained by long-wavelength polar lattice vibrations and dipole relaxations capable of responding to electrical bias; therefore spectroscopic methods, such as Raman spectroscopy, can be used to investigate its origin. Herein, we used angle-resolved polarized Raman mapping to investigate how phase boundaries and giant dielectric responses are related in a relaxor-Pb(Mg1/3Nb2/3)O-3-ferroelectric-PbTiO3 (PMN-xPT) solid-solution system using a compositionally graded crystal, with gradual changes in polarization direction visualized by Raman mapping. The variation of the width of quasielastic light scattering with position reveals the following: The huge dielectric response observed in PMN-xPT is ascribable to the slowing down of a relaxation related to mesoscopic ferroelectric domains near the phase boundary, which is characteristic of relaxor-ferroelectric solid-solution systems and differentiates them from other ferroelectrics. Relaxor ferroelectrics exhibit fascinating physical properties, ranging from large dielectric responses to enhanced performance of ultrasonic transducers. Here, the authors apply angle-resolved polarized Raman mapping to study the origin of the emergent giant dielectric response in a relaxor-ferroelectric solid solution.