Publications de Nava Setter | EPFL Graph Search

Chattez avec Graph Search

Posez n’importe quelle question sur les cours, conférences, exercices, recherches, actualités, etc. de l’EPFL ou essayez les exemples de questions ci-dessous.

AVERTISSEMENT : Le chatbot Graph n'est pas programmé pour fournir des réponses explicites ou catégoriques à vos questions. Il transforme plutôt vos questions en demandes API qui sont distribuées aux différents services informatiques officiellement administrés par l'EPFL. Son but est uniquement de collecter et de recommander des références pertinentes à des contenus que vous pouvez explorer pour vous aider à répondre à vos questions.

A micro-pump for medical applications is being developed using organometallic derived PZT thin films and silicon micromachining technology. Critical issues include the deposition of 'thick' PZT films (1 to 2 mu m thickness), film processing compatibility with available Si/SixNy/Ta/Pt structures and the establishing of piezoelectric poling parameters. A processing technique for the preparation of thick PZT films is presented. Piezoelectric properties are characterized by both direct method using alternating

A study was conducted on the effects of compositional modifications on the temperature coefficient of resonance frequency (TCF) in the disc planar vibration mode for the bismuth layer-structured compound SrBi2Nb2O9 (SBN)-based ceramics. The substitution of the strontium site by divalent and trivalent ions improved the TCF, accompanying the relaxation of elastic anomaly. The tolerance factor, t, was calculated for a pseudo cubic block to study the contribution of the structural factor to Curie temperature, T

The impact of electrode-adjacent passive layers on the small signal dielectric response of a ferroelectric film containing a 180degrees-domain pattern has been analyzed. It is shown that, for a realistic physical situation, the so-called "in-series capacitors formula" is still applicable for the description of the dielectric response of this system, however, with some apparent values of the passive-layer permittivity epsilon(mod), which is a function of parameters of the ferroelectric and the layers. It is

A modified processing method for lead nickel niobate-lead zirconate titanate (Pb(Ni1/3Nb2/3)O-3-Pb(Zr,Ti)O-3, PNN-PZT) solid solutions is presented. This method is based on the high-temperature synthesis of a precursor that contains all the B-site cations (Ti, Zr, Ni, and Nb). This synthesis yields a diphasic mixture that contains a ZrTiO4-like phase and a rutile-like phase. Both phases exhibit a cationic valence of 4; thus, it is concluded that the mixing of Ni and Nb cations is adequate for the preparatio

In the present study, piezoelectric, conductivity and dielectric measurements have been performed on virgin and fatigued ferroelectric PZT thin films prepared by spin-on sol-gel deposition process on Si/SiO2/Ti/Pt substrates. By fatiguing, the polarisation shows a strong exponential degradation, the hysteresis loops of the piezoelectric coefficient d(33) become smaller and asymmetric and the polarisation-induced asymmetry of the conductivity at low voltage and the relative permittivity both decrease. The en

An efficient, electrically conductive, chemical barrier for the integration of piezoelectric Pb(Zr,Ti)O3 (PZT) films on reactive metal substrates has been developed, opening new possibilities for PZT integration on micromechanical and semiconductor devices, Very reactive zir conium films have been taken in order to test the quality of the specially designed RuO2/Cr buffer under the condition of in situ sputter deposition of PZT at 600 degrees C. The PZT/RuO2 interface was found to be free of intermediate ph

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 verifiable predictions can be made on thick films. We illustrate this approach by applying it to SrRuO3/BaTiO3/SrRuO3 heterostructures with different terminations of the metal-oxide electrodes.

The (1-x)Pb(Sc1/2Nb1/2)O-3-xPbTiO(3)(x=0.4, PSNT(60/40)) thin films near the morphotropic phase boundary(MPB) composition were successfully deposited via sol-gel method. Taking the strict controls of processing factors such as the stable and homogeneous precursor solutions, conditions of heat treatment and suitable substrates, it was possible to obtain the pyrochlore-free PSNT(60/40) thin films. The effect of substrate on the microstructure and crystallographic orientation is shown. Dielectric behaviors of

An attractive combination of properties of the ferroelectric copolymer of vinylidene fluoride and trifluoroethylene (P(VDF-TrFE)), including a relatively high spontaneous polarization and low dielectric constant as well as low processing temperature makes this material useful for studying the ferroelectric gate operation for 1T nonvolatile ferroelecetric memory applications. Here we explore a silicon-based ferroelectric field effect transistor with P(VDF-TrFE) gate showing a persistent switching of the drai

Pb(Zr-x, Ti1-x)O-3 (PZT) piezoelectric thin films are of major interest in MEMS technology for their ability to provide electro-mechanical coupling. In this work, the effective transverse piezoelectric coefficient e(31,f) of sol-gel processed films was investigated as a function of composition, film texture and film thickness. Dense, textured and crack-free PZT films have been obtained on silicon substrates up to a thickness of 4 mum. Crystallization anneals have been performed for every 0.25 mum. Nucleatio

Thin films of neodymium-modified bismuth titanate Bi3.44Nd0.56Ti3O12 (BNT) were grown on Pt/TiO2/SiO2/Si substrates using chemical solution deposition method. The capacitors made by applying top Au electrodes on BNT films showed significantly improved values of the remanent polarization as compared to that using bismuth titanate Bi4Ti3O12 (BT) films. The 2P(r) value for the BNT capacitors was determined to be equal to 38 muC/cm(2) at an applied voltage of 24 V, whereas, for Bi4Ti3O12 ( BT) capacitors a valu

It is shown that a strong but diffuse dielectric anomaly, commonly expected only in disordered ferroelectrics, may be inherent in strained and defect-free perovskite ferroelectric thin films. The origin of this unusual anomaly, which was never predicted for a defect-free system, is the overcritical trace of a critical point in the film phase diagram, This possibility is illustrated by the mean-field thermodynamic calculations performed for (111)-oriented PbTiO3 films epitaxially grown on dissimilar cubic su

Having a composition closed to the morphotropic phase boundary, PZT films of 14 mu m thickness with a porosity less than 7% were prepared by the double print double firing method. At room temperature the dielectric constant, remanent polarization and coercive field were equal to 1040, 24 mu C/cm(2) and 19kV/cm respectively. The coercive field of thick films has a value between the bulk ceramics and thin films values. At the temperature of the transition the dielectric constant is 15000. This value is far su

ZnO and AlN, which exhibit the wurtzite structure, were deposited onto metal coated SiO2 substrates by sputtering. X-ray diffraction (XRD) indicated that the films contained no second phases and exhibited an [0001] texture. Transmission electron microscopy (TEM) observations confirmed the XRD results and revealed the columnar microstructure of the films. The width of the columnar grains were less than 30 nm for AIN and between 100 and 400 nm for ZnO. In the ZnO grains, a large concentration of defects were

Nanocomposite films consisting of BaTiO3 and CeO2 have been grown by a self-assembled approach. The composite structure of those films varied with the volume fractions of BaTiO3 and CeO2. A BaTiO3 in the form of inclined nano-fibers embedded in CeO2 matrix was obtained for CeO2-rich composition, which results in an appreciable tunability with a very low permittivity of 50. The observed tunable properties imply the competitive potential of BaTiO3-CeO2 composite as an alternative tunable material.

A review of the properties of ferroelectric materials that are relevant to microwave tunable devices is presented: we discuss the theory of dielectric response of tunable bulk materials and thin films; the experimental results from the literature and from own work are reviewed; the correspondence between the theoretical results and the measured properties of tunable materials is critically analyzed; nominally pure, real (defected), and composite bulk materials and thin films are addressed. In addition, tech

Enhancement of ferroelectric properties, both spontaneous polarization and Curie temperature under negative pressure had been predicted in the past from first principles and recently confirmed experimentally. In contrast, piezoelectric properties are expec ...

Two W protection schemes for direct-contact bottom electrodes for PZT thin films, namely RuO2/Cr and RuO2/Ru, were compared with respect to protective performance and contact resistance up to 800 degrees C annealing temperature in oxygen. Cr clearly offers better protection for W than Ru-based schemes by forming a passivating Cr2O3 layer. No Cr is detected on the RuO2 surface, even after annealing at 800 degrees C, due to its entrapment by RuO2 by oxidoreduction. However, the formation of a continuous Cr2O3

Dielectric properties of K(Ta0,55Nb0,45)O-3 [KTN] single crystals with < 100 > and < 011 > crystallographic orientation were studied. Temperature dependencies of dielectric permittivity of monodomain and polydomain crystals of these orientations are compar ...

An all-fiber phase modulator based on lead titanate zirconate coating deposited by dc reactive magnetron sputtering was fabricated and optically characterized. The frequency response showed a flat broadband structure up to 600 kHz, with an efficiency of 0.73 rad/(V m). This is an order of magnitude higher than that for sputtered zinc oxide based phase modulators. Radial mode resonance peaks were observed between 10 and 700 MHz, with a maximum phase modulation amplitude of 0.3 rad at the fundamental radial r

Nava Setter

Chattez avec Graph Search

PZT films for micro-pumps

Properties of the elastic anomaly in SrBi2Nb2O9-based ceramics

Size effect on permittivity in ferroelectric polydomain thin films

Synthesis of lead nickel niobate-lead zirconate titanate solid solutions by a B-site precursor method

Characterisation of the fatigued state of ferroelectric PZT thin-film capacitors

Pb(Zr,Ti)O3 thin films on zirconium membranes for micromechanical applications

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

Preparation and dielectric properties of Pb(Sc1/2Nb1/2)O-3-PbTiO3 thin films near MPB compositions

Ferroelectric Polymer Gate Transistor as a Model System for Exploring the Mechanisms of the Retention Loss

{100}-textured, piezoelectric Pb(Zr-x Ti1-x)O-3 thin films for MEMS: integration, deposition and properties

Properties of chemical solution deposited polycrystalline neodymium-modified Bi4Ti3O12

Strain-induced diffuse dielectric anomaly and critical point in perovskite ferroelectric thin films

Screen printed PZT layer-fabrication and properties

Microstructure and defects of wurtzite structure thin films

Self-assembled ferroelectric-dielectric nanocomposite films for tunable applications

Ferroelectric materials for microwave tunable applications

Piezoelectric enhancement under negative pressure

Conducting barrier electrodes for direct contact of PZT thin films on tungsten

Dielectric properties of K(Ta0.55Nb0.45)O-3 Single Crystal

All-fiber phase modulator based on lead zirconate titanate thin-film coating