Defect thermodynamics and kinetics in thin strained ferroelectric films: The interplay of possible mechanisms

Morozovska, Anna N.; Eliseev, Eugene A.; Krishnan, P. S. Sankara Rama; Tselev, Alexander; Strelkov, Evgheny; Borisevich, Albina Y.; Varenyk, Olexander V.; Morozovsky, Nicholas V.; Munroe, Paul; Kalinin, Sergei V.; Valanoor, Nagarajan

doi:10.1103/physrevb.89.054102

Cited by 28 publications

(18 citation statements)

References 61 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…79,84,85 However, growth of films beyond the critical thickness for strain relaxation results in formation of dislocations. These dislocations have been predicted [86][87][88][89][90][91][92][93] and shown 41,[94][95][96][97][98][99] to affect the ferroelectric and dielectric properties. In epitaxial Ba 0.6 Sr 0.4 TiO 3 films, a suppression of the permittivity was reported and explained by a concentration of misfit dislocations (~10 11 cm À2 ) altering the dielectric stiffness.…”

Section: August 2016mentioning

confidence: 99%

Scaling Effects in Perovskite Ferroelectrics: Fundamental Limits and Process‐Structure‐Property Relations

et al. 2016

View full text Add to dashboard Cite

Ferroelectric materials are well‐suited for a variety of applications because they can offer a combination of high performance and scaled integration. Examples of note include piezoelectrics to transform between electrical and mechanical energies, capacitors used to store charge, electro‐optic devices, and nonvolatile memory storage. Accordingly, they are widely used as sensors, actuators, energy storage, and memory components, ultrasonic devices, and in consumer electronics products. Because these functional properties arise from a noncentrosymmetric crystal structure with spontaneous strain and a permanent electric dipole, the properties depend upon physical and electrical boundary conditions, and consequently, physical dimension. The change in properties with decreasing physical dimension is commonly referred to as a size effect. In thin films, size effects are widely observed, whereas in bulk ceramics, changes in properties from the values of large‐grained specimens is most notable in samples with grain sizes below several micrometers. It is important to note that ferroelectricity typically persists to length scales of about 10 nm, but below this point is often absent. Despite the stability of ferroelectricity for dimensions greater than ~10 nm, the dielectric and piezoelectric coefficients of scaled ferroelectrics are suppressed relative to their bulk counterparts, in some cases by changes up to 80%. The loss of extrinsic contributions (domain and phase boundary motion) to the electromechanical response accounts for much of this suppression. In this article, the current understanding of the underlying mechanisms for this behavior in perovskite ferroelectrics is reviewed. We focus on the intrinsic limits of ferroelectric response, the roles of electrical and mechanical boundary conditions, grain size and thickness effects, and extraneous effects related to processing. In many cases, multiple mechanisms combine to produce the observed scaling effects.

show abstract

Section: August 2016mentioning

confidence: 99%

Scaling Effects in Perovskite Ferroelectrics: Fundamental Limits and Process‐Structure‐Property Relations

et al. 2016

View full text Add to dashboard Cite

show abstract

“…Continuous approximation for the concentration of the electrons in the conduction band is consistent with the following expression for electro-chemical potential [31]:…”

Section: Continuity Equation For Donor Concentrationmentioning

confidence: 57%

Self-consistent modelling of electrochemical strain microscopy in mixed ionic-electronic conductors: Nonlinear and dynamic regimes

Varenyk

Silibin

Киселев

et al. 2015

Journal of Applied Physics

View full text Add to dashboard Cite

Dynamic Electrochemical Strain Microscopy (ESM) response of mixed ionic-electronic conductors is analysed in the framework of the Thomas-Fermi screening theory and Vegard law with accounting of the steric effects. The emergence of dynamic charge waves and nonlinear deformation of the surface as result of applying probing voltage is numerically explored. 2D maps of the strain and concentration distribution across the mixed ionic-electronic conductor and bias-induced surface displacements for ESM microscopy were calculated. Obtained numerical results can be of applied to quantify ESM response of Li-based solid electroytes, materials with resistive switching and electroactive ferroelectric polymers, which are of potential interest for flexible and high-density non-volatile memory devices

show abstract

“…In the case, the proportionality coefficient is determined either from the ab-initio calculation [37] or from experiments [38,39]. It should be noted that the influence of Vegard strain, coming from the diffusion and the accumulation of defects near the interfaces of ferroelectric thin films, results in the pronounced change of their polar properties [40,41]. Therefore it is natural to expect that one could not neglect Vegard strains when describing polar properties of ferroelectric nanoparticles.…”

Section: Surface Stress (Originated From the Surface Tension)mentioning

confidence: 99%

Effect of Vegard strains on the extrinsic size effects in ferroelectric nanoparticles

et al. 2014

Self Cite

View full text Add to dashboard Cite

By changing the size and the shape of ferroelectric nanoparticles, one can govern their polar properties including their improvements in comparison with the bulk prototypes. At that the shift of the ferroelectric transition temperature can reach as much as hundreds of Kelvins. Phenomenological description of these effects was proposed in the framework of Landau-Ginsburg-Devonshire (LGD) theory using the conceptions of surface tension and surface bond contraction. However, this description contains a series of poorly defined parameters, which physical nature is ambiguous. It is appeared that the size and shape dependences of the phase transition temperature along with all polar properties are defined by the nature of the size effect.Existing LGD-type models do not take into account that defects concentration strongly increases near the particle surface. In order to develop an adequate phenomenological description of size effects in ferroelectric nanoparticles, one should consider Vegard strains (local lattice deformations) originated from defects accumulation the near surface.In the paper we propose a theoretical model that takes into account Vegard strains and perform a detailed quantitative comparison of the theoretical results with experimental ones for quasi-spherical nanoparticles, which reveal the essential (about 100 K) increase of the transition temperature in spherical nanoparticles in comparison with bulk crystals. The average radius of nanoparticles was about 25 nm, they consist of KTa 1х Nb х O 3 solid solution, where KTaO 3 is a quantum paraelectric, while KNbO 3 is a ferroelectric. From the comparison between the theory and experiment we unambiguously established the leading contribution of Vegard strains into the extrinsic size effect in ferroelectric nanoparticles. We determined the dependence of * Corresponding author 1: anna.n.morozovska@gmail.com † Corresponding author 2: isgolovina@ukr.net 1 Vegard strains on the content of Nb and reconstructed the Curie temperature dependence on the content of Nb using this dependence. Appeared that the dependence of the Curie temperature on the Nb content becomes non-monotonic one for the small (< 20 nm) elongated KTa 1-х Nb х O 3 nanoparticles. We established that the accumulation of intrinsic and extrinsic defects near the surface can play the key role in the physical origin of extrinsic size effect in ferroelecric nanoparticles and govern its main features.

show abstract

Defect thermodynamics and kinetics in thin strained ferroelectric films: The interplay of possible mechanisms

Cited by 28 publications

References 61 publications

Scaling Effects in Perovskite Ferroelectrics: Fundamental Limits and Process‐Structure‐Property Relations

Scaling Effects in Perovskite Ferroelectrics: Fundamental Limits and Process‐Structure‐Property Relations

Self-consistent modelling of electrochemical strain microscopy in mixed ionic-electronic conductors: Nonlinear and dynamic regimes

Effect of Vegard strains on the extrinsic size effects in ferroelectric nanoparticles

Contact Info

Product

Resources

About