Engineering Relaxor Behavior in (BaTiO₃)_n/(SrTiO₃)_n Superlattices

Abstract

Complex‐oxide superlattices provide a pathway to numerous emergent phenomena because of the juxtaposition of disparate properties and the strong interfacial interactions present in these unit‐cell‐precise structures. This is particularly true in superlattices of ferroelectric and dielectric materials, wherein new forms of ferroelectricity, exotic dipolar textures, and distinctive domain structures can be produced. Here, relaxor‐like behavior, which is typically associated with the chemical inhomogeneity and complexity of solid solutions, is observed in (BaTiO3)n/(SrTiO3)n (n = 6–20 unit cells) superlattices. Dielectric studies and subsequent Vogel‐Fulcher analysis show significant frequency dispersion of the dielectric maximum across a range of periodicities, with enhanced dielectric constant and more robust relaxor behavior for smaller period n. Bond valence molecular‐dynamics simulations predict the relaxor‐like behavior observed experimentally, and interpretations of the polar patterns via 2D discrete‐wavelet transforms in shorter‐period superlattices suggest that the relaxor behavior arises from shape variations of the dipolar configurations, in contrast to frozen antipolar stripe domains in longer‐period superlattices (n = 16). Moreover, the size and shape of the dipolar configurations are tuned by superlattice periodicity, thus providing a definitive design strategy to use superlattice layering to create relaxor‐like behavior which may expand the ability to control desired properties in these complex systems.This article is protected by copyright. All rights reserved

Pressure-induced electronic to ionic phase transition and recurrence of ferroelectricity in PbTiO3

“…Inorganic perovskite oxides are ancient materials but still a hot topic today in the fields of physics, material science, and electronics. 1–9 Lead titanate (PbTiO 3 ) is one of the most representative chemicals of the ABO 3 -type perovskite oxide. A perfect ABO 3 -type perovskite oxide should have a cubic lattice but the PbTiO 3 crystal is distorted spontaneously into a tetragonal structure at room temperature.…”