Publications by Nava Setter | EPFL Graph Search

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The phenomenon of time-dependent polarization loss in poled ferroelectric capacitors, also known as retention, represents one of the most important reliability issues for ferroelectric nonvolatile memories. In a number of publications different ways to con ...

Ultrathin films of the ferroelectric polymer poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] have recently attracted intensive research interest due to their potential applications in emerging organic devices. As special geometry confinement syst ...

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 ...

Three ceramic preparations of lead scandium tantalate were chosen for the present study because they exhibit three different relaxer-type dielectric response behaviours. Two preparations, made in lead-rich atmospheres, so as to conserve virtually 100% occupancy of the perovskite (ABO(3)) A sites, were annealed or quenched so as to yield extreme values for the long-range order parameter (s) for (Sc, Ta) ordering on the perovskite B site;thus s = 0.93 and 0.10 for pst-o and pst-d, respectively. The third prep

The relaxor ferroelectric PbMg1/3Nb2/3O3 (PMN) is investigated by means of dielectric and Fourier transform far infrared transmission spectroscopy in ,the frequency range from 10 kHz to 15 THz at temperatures between 20 and 900 K using mostly thin films on ...

The contrast mechanisms of domain imaging experiments assisted by atomic force microscope (AFM) have been investigated by model experiments on nonpiezoelectric (silicon oxide) and piezoelectric [Pb(Zr,Ti)O-3] thin films. The first step was to identify the electrostatic charge effects between the tip, the cantilever, and the sample surface. The second step was to explore the tip-sample piezoelectric force interaction. The static deflection of the cantilever was measured as a function of dc bias voltage (V-dc

We report a 2-step approach to prepare tetragonal perovskite PbZr0.1Ti0.9O3 submicro/nano wires in gram scale and with over 95% wire content. Non-perovskite precursor wires were first fabricated by hydrothermal processing. A subsequent annealing in a PbO a ...

The effects of niobium doping on the hysteresis parameters of sol-gel Pb-1.1-x/2(Zr0.53Ti0.47)(1-x)NbxO3 (0 < x < 0.05) have been reported fbr two sets of films with analogous grain size and degree of (111) texture but with different surface microstructures. For both sets, a strong continuous decay of the remnant and maximum polarizations and slope of the hysteresis loop at the coercive field was observed with increasing niobium concentration. The held dependence of the remnant polarization for any given ni

The influence of flexoelectric coupling on the internal structure of neutral domain walls in the tetragonal phase of perovskite ferroelectrics is studied. The effect is shown to lower the symmetry of 180 degrees walls which are oblique with respect to the ...

Pyrochlore free Pb(Mg1/3Nb2/3)O-3 (PMN) thin films were prepared from alkoxide-based solution precursors. The influence of different seeding layers and chemical solution on the microstructures is shown. Dielectric, electrostrictive, and piezoelectric properties of the films were characterized in detail. Films show relaxor-like behavior, but with dielectric permittivity which is low (around 4000 at peak) compared to bulk ceramics and single crystals. Several parameters which might be responsible for this low

The phenomenon of polarization imprint consisting of the development of a preferential polarization state in ferroelectric films is known as one of the major issues impacting the development of high density ferroelectric memories. According to the commonly accepted scenario, the imprint is related to the charge injection and charge accumulation in the nearby-electrode passive layer of the ferroelectric film. Recent studies demonstrated that the coercive voltage shift induced by the imprint exhibits a nonlin

All-fiber optical phase modulators were fabricated by coating standard telecommunication optical fibers with thin films of piezoelectric ZnO. Piezoelectric optical fiber coatings of PbZrxTi1-xO3(PZT) were also produced, and the actuation capability necessary for making optical fiber modulators is demonstrated. Both the ZnO and the PZT fiber coatings were deposited by reactive direct current magnetron sputtering of metal targets. The geometry of the sputtering system, fiber rotation, and reactive sputtering

A novel piezoelectric thin-film accelerometer has been designed and its performance has been analysed. The piezoelectric thin film (PZT for example) is delineated into an array of pads to reduce the sensor capacitance. By filling the cavity around the PZT pads either with a polymer or a gas with controlled pressure, damping can be controlled. The piezoelectric thin-film material (i.e., pads) is clamped between a seismic mass and a base plate (silicon substrate). During acceleration in the axial direction th

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 polarization profile across the walls are derived for several limiting cases and wall widths are estimated. It is shown analytically that different regimes of screening and different dependences for the width of charged domain walls on the temperature and p

Impurity elements used as dopants are essential to semiconductor technology for controlling the concentration of charge carriers. Their location in the semiconductor crystal is determined during the fabrication process and remains fixed. However, another p ...

Electrode stability, interdiffusion, phase purity and deviation from stoichiometry at the PZT-electrode interface are key issues in PZT thin film integration. This article highlights the use of transmission electron imaging combined with energy dispersive spectroscopy (EDS) for the investigation of these phenomena. The accuracy of the EDS analysis is discussed. It will be shown that using a standard PZT sample and controlled conditions, reliable analysis can be performed. Diffusion mechanisms have been stud

Structural and dielectric properties of epitaxial SrTiO3 (STO) thin films on LaAlO3 substrates fabricated by a two-step growth technique using pulsed laser deposition were investigated by in situ and ex situ observations in terms of strain relaxation from ...

Fiber optic modulators were fabricated by coating optical fibers with electrode and piezoelectric ZnO layers. The techniques of piezoelectric fiber optic modulator (PFOM) fabrication are presented, and the microstructure and crystallographic texture of the coatings are analyzed, Ln order to produce thick (approximately 5 mu m) ZnO coatings, it was necessary to study the reactive de magnetron sputtering process in O-2/Ar gas mixtures under conditions close to the transition between an oxidized and nonoxidize

The domain nucleation and growth during polarization switching in Pb(Zr,Ti)O-3 (PZT) ferroelectric thin film capacitors with Pt top (TE) and bottom electrodes (BE) were studied by means of atomic force microscopy (AFM). The experimental configuration used in this study differs from that conventionally used (AFM tip/PZT/BE) where the AFM tip acts as a positionable TE. A small ac voltage was applied between the electrodes with a step by step increasing dc bias voltage. The induced piezoelectric vibration was

The effect of varying the thickness of Pt top electrodes made by the electron beam induced deposition technique on the domain nucleation characteristics of Pb(Zr,Ti)O-3 films has been investigated by piezoresponse force microscopy. The advantage of this ex ...

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Physical model of retention and temperature-dependent polarization reversal in ferroelectric films

Thermally Induced Cooperative Molecular Reorientation and Nanoscale Polarization Switching Behaviors of Ultrathin Poly(vinylidene fluoride-trifluoroethylene) Films

Strong ferroelectric domain-wall pinning in BiFeO3 ceramics

Relationship between Nanostructure and Dielectric Response of Lead Scandium Tantalate .1. Structure and Domain Textures

Soft and central mode behaviour in PbMg1/3Nb2/3O3 relaxor ferroelectric

Principle of ferroelectric domain imaging using atomic force microscope

Large-scale fabrication of titanium-rich perovskite PZT submicro/nano wires and their electromechanical properties

Use of ferroelectric hysteresis parameters for evaluation of niobium effects in lead zirconate titanate thin films

Bichiral structure of ferroelectric domain walls driven by flexoelectricity

Electromechanical properties and self-polarization in relaxor Pb(Mg1/3Nb2/3)O-3 thin films

Nature of nonlinear imprint in ferroelectric films and long-term prediction of polarization loss in ferroelectric memories

Sputter deposited piezoelectric fiber coatings for acousto-optic modulators

Design of a novel thin-film piezoelectric accelerometer

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

Polarization charge as a reconfigurable quasi-dopant in ferroelectric thin films

Stoichiometry and interdiffusion in PZT thin films studied by transmission electron microscopy

Structural and dielectric properties of strain-controlled epitaxial SrTiO3 thin films by two-step growth technique

Fabrication and structural analysis of ZnO coated fiber optic phase modulators

High resolution study of domain nucleation and growth during polarization switching in Pb(Zr,Ti)O-3 ferroelectric thin film capacitors

Domain nucleation behavior in ferroelectric films with thin and ultrathin top electrodes versus insulating top layers