Concept

Électret

Publications associées (57)

Macroscopic Theory of Charged Domain Walls in Ferroelectrics

This thesis consists of a theoretical analysis of charged domain walls in ferroelectrics based on Landau theory and the theory of semiconductors. First, the internal structure of a 180-degree charged domain wall is considered. It is shown that different re ...

EPFL2012

Head-to-head and tail-to-tail 180^{°} domain walls in an isolated ferroelectric

Nava Setter, Alexander Tagantsev, Maxim Gureev

Head-to-head and tail-to-tail 180 degrees domain walls in a finite isolated ferroelectric sample are theoretically studied using Landau theory. The full set of equations, suitable for numerical calculations, is developed. The explicit expressions for the p ...

2011

Strong ferroelectric domain-wall pinning in BiFeO3 ceramics

Nava Setter, Dragan Damjanovic, Marija Kosec

We have studied the polarization-electric-field hysteresis, the dielectric permittivity dispersion, the piezoelectric properties, the electric-field-induced strain, and the interrelations between these properties for bismuth ferrite (BiFeO3) ceramics. The ...

American Institute of Physics2010

Effective permittivity of porous media: a critical analysis of the complex refractive index model

Alessandro Brovelli

The availability of reliable constitutive models linking he bulk electric properties of porous media to their inner structure is a key requirement for useful quantitative applications of noninvasive methods. This study focuses on the use of dielectric meas ...

2008

Surface-stimulated phenomena in the polarization response of ferroelectrics

Guido Gerra

The integration of ferroelectrics in electronic devices requires that they be used in the form of thin films, which implies that for such systems finite-size effects related to the presence of a ferroelectric-electrode interface become important. In this t ...

EPFL2008

First-principles description of ferroelectric/electrode interfaces and properties of not very thin ferroelectric capacitors

Nava Setter, Alexander Tagantsev, Guido Gerra

We formulate an approach to the size effect problem in ferroelectric-electrode systems where ab initio calculations are combined with a phenomenological framework. The parameters of the model can be extracted from the calculations, while experimentally ver ...

Ieee Service Center, 445 Hoes Lane, Po Box 1331, Piscataway, Nj 08855-1331 Usa2007

Ferroelectric gate on AlGaN/GaN heterostructures

Lisa Malin

The capability of switching the spontaneous polarisation under an applied electric field in ferroelectric materials can be exploited for the use in low power, non-volatile, re-writable memory devices. Currently available commercially is ferroelectric rando ...

EPFL2007

Ionic polarizability of conductive metal oxides and critical thickness for ferroelectricity in BaTiO3

Nava Setter, Alexander Tagantsev, Guido Gerra

We report a first-principles investigation of ultrathin BaTiO3 films with SrRuO3 electrodes. We find that the ionic relaxations in the metal-oxide electrode play a crucial role in stabilizing the ferroelectric phase. Comparison with frozen-phonon calculati ...

2006

Phase transitions, anisotropy and domain engineering

Matthew Davis

Relaxor-ferroelectric single crystals PZN-xPT [(1-x)Pb(Zn1/3Nb2/3)O3-xPbTiO3] and PMN-xPT [(1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3] continue to attract much interest due to their anomalously large piezoelectric properties (d33 > 2000 pm/V; k33 > 90%) when poled ("do ...

EPFL2006

Static dielectric properties of carbon nanotubes from first principles

Nicola Marzari, Boris Kozinsky

We characterize the response of isolated single-wall (SWNT) and multiwall (MWNT) carbon nanotubes and nanotube bundles to static electric fields using first-principles calculations and density-functional theory. The longitudinal polarizability of SWNTs sca ...

2006

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