Atomistic determination of flexoelectric properties of crystalline dielectrics
R. Maranganti,Pradeep Sharma +1 more
Reads0
Chats0
TLDR
In this article, a lattice dynamics based microscopic approach is used to estimate the flexoelectric tensor of perovskite dielectrics, and the authors compare their estimates with experimental/theoretical values.Abstract:
Upon application of a uniform strain, internal sublattice shifts within the unit cell of a noncentrosymmetric dielectric crystal result in the appearance of a net dipole moment: a phenomenon well known as piezoelectricity. A macroscopic strain gradient on the other hand can induce polarization in dielectrics of any crystal structure, even those which possess a centrosymmetric lattice. This phenomenon, called flexoelectricity, has both bulk and surface contributions: the strength of the bulk contribution can be characterized by means of a material property tensor called the bulk flexoelectric tensor. Several recent studies suggest that strain-gradient induced polarization may be responsible for a variety of interesting and anomalous electromechanical phenomena in materials including electromechanical coupling effects in nonuniformly strained nanostructures, ``dead layer'' effects in nanocapacitor systems, and ``giant'' piezoelectricity in perovskite nanostructures among others. In this work, adopting a lattice dynamics based microscopic approach we provide estimates of the flexoelectric tensor for certain cubic crystalline ionic salts, perovskite dielectrics, $III\text{\ensuremath{-}}V$ and $II\text{\ensuremath{-}}VI$ semiconductors. We compare our estimates with experimental/theoretical values wherever available and also revisit the validity of an existing empirical scaling relationship for the magnitude of flexoelectric coefficients in terms of material parameters. It is interesting to note that two independent groups report values of flexoelectric properties for perovskite dielectrics that are orders of magnitude apart: Cross and co-workers from Penn State have carried out experimental studies on a variety of materials including barium titanate while Catalan and co-workers from Cambridge used theoretical ab initio techniques as well as experimental techniques to study paraelectric strontium titanate as well as ferroelectric barium titanate and lead titanate. We find that, in the case of perovskite dielectrics, our estimates agree to an order of magnitude with the experimental and theoretical estimates for strontium titanate. For barium titanate however, while our estimates agree to an order of magnitude with existing ab initio calculations, there exists a large discrepancy with experimental estimates. The possible reasons for the observed deviations are discussed.read more
Citations
More filters
Journal ArticleDOI
Flexoelectric Effect in Solids
TL;DR: Flexoelectricity is a universal effect allowed by symmetry in all materials as discussed by the authors and has been studied in many nanoscale systems, and potential applications of this electromechanical phenomenon have been discussed.
Journal ArticleDOI
Mechanical Writing of Ferroelectric Polarization
Haidong Lu,Chung Wung Bark,D. Esqué-de los Ojos,Jorge Alcalá,Chang-Beom Eom,Gustau Catalan,Alexei Gruverman +6 more
TL;DR: It is demonstrated that the stress gradient generated by the tip of an atomic force microscope can mechanically switch the polarization in the nanoscale volume of a ferroelectric film, enabling applications in which memory bits are written mechanically and read electrically.
Journal ArticleDOI
Fundamentals of flexoelectricity in solids
TL;DR: This review paper presents a critical analysis of the current knowledge on the flexoelectricity in common solids, excluding organic materials and liquid crystals.
Journal ArticleDOI
Flexoelectric rotation of polarization in ferroelectric thin films
Gustau Catalan,Axel Lubk,A. H. G. Vlooswijk,Etienne Snoeck,César Magén,César Magén,A. Janssens,G. Rispens,Guus Rijnders,D. H. A. Blank,Beatriz Noheda +10 more
TL;DR: This work has studied the strain distribution inside epitaxial films of the archetypal ferroelectric PbTiO(3), where the mismatch with the substrate is relaxed through the formation of domains (twins).
Journal ArticleDOI
Piezoelectric nanogenerators—Harvesting ambient mechanical energy at the nanometer scale
TL;DR: In this paper, theoretical calculations and experimental characterization methods for predicting or determining the piezoelectric potential output of nanowires are reviewed first, and representative models of NGs are then discussed for harvesting mechanical energy from high-frequency acoustic waves and low-frequency vibrations/frictions.
References
More filters
Posted Content
Giant flexoelectric effect in two-dimensional boron-nitride sheets
TL;DR: In this paper, it was shown that a single-atom-thick boron-nitride (BN) sheet exhibits an unusual nonlinear electromechanical effect: it becomes macroscopically polarized when bent out-of-plane.