Publications by Nava Setter | EPFL Graph Search

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The processing and characterization of electrical properties of potassium niobate ceramic, KNbO3 (KN) have been studied. The difficulty of obtaining dense samples by conventional methods limits the knowledge on electrical properties of this material. In this paper, a complete route for processing of KN with density over 94% is described. Piezoelectric and dielectric data are presented. It is observed that the major problem concerning the density is related to incorrect stoichiometry, which is believed to be

A fiber-based flexural actuator was developed using a patterned piezoelectric ZnO/electrode fiber coating on a standard telecommunications optical fiber. The actuator was composed of a concentric inner Cr/Au electrode, a thick sputtered ZnO coating, and an outer Cr/Au electrode. Using standard photolithography, 30-mu m wide gaps in one of the electrodes were patterned along 2-cm lengths parallel with the fiber axis. This device can be driven in a bimorph mode. It was demonstrated that a split electrode actu

Low-frequency losses in weakly anharmonic cubic centrosymmetric crystals as a function of permittivity are estimated using phonon kinetics approach. It is shown that very steep dependencies up to the fifth power of permittivity (epsilon'' is-proportional-to epsilon(o)5) as recently observed in the Ba (B'1/2B''1/2)O3 complex perovskite systems may be expected in case of small dispersion of optical phonon branches. The extrapolation down from the high-frequency one-phonon absorption range using a classical da

Interferometric measurements of electric field-induced displacements in piezoelectric thin films using single-beam and double-beam optical detection schemes are reported. It is shown that vibrational response measured with a single-beam interferometer includes a large contribution of the bending motion of substrate. Therefore, it is difficult to apply single-beam technique for piezoelectric measurements in thin films. To suppress the bending effect a high-resolution double-beam interferometer is proposed. T

Size effect in ferroelectrics is treated as a competition between the geometrical symmetry of the ferroelectric sample and its crystalline symmetry. Polarization rotation is shown to be a clear finite size effect that results from this competition, which can be induced by all types of driving forces that are coupled with the sample geometry, such as electrical, mechanical and/or thermal. The concept is illustrated with the Landau theory analysis of the polarization state of a cylindrical nanowire of the pro

In this paper, we report on the performance of microwave phase shifters implemented on sol-gel derived Ba0.3Sr0.7TiO3 (BST) thin films. Coplanar waveguide (CPW) phase shifters, loaded-line phase shifters, and reflection-type digital phase shifters; have been realized on a single alumina substrate covered with a 300nm-thick BST film. The performances of different types of phase shifting cells are compared. It is shown that the optimally designed digital phase shifters have better performance although the dig

Strain-field measurements and in situ polarized light microscopy have been used to evidence a hysteretic, irreversible electric-field-induced transition to a quasimonodomain rhombohedral phase in 111-oriented, pseudo-orthorhombic PZN-8PT [0.92Pb(Zn1/3 ...

A unified approach for analysis of polarization fatigue and size effects on ferroelectric switching in relationship with injection and entrapment of charge at the interfacial layer of the ferroelectric film is developed. The proposed model suggests that an enhancement of the entrapped charge relaxation at the interfaces has a positive impact on both the polarization fatigue and size effects. This concept is implemented experimentally by introducing a thin conductive oxide (RuO2) layer into the top interface

Deposition of a hydrothermal method has a number of advantages; low deposition temperature, high-purity, deposition on a three-dimensional structure, and a large thickness. The present paper investigates the improvement of an epitaxial lead zirconate titanate (PZT) thin film deposited via hydrothermal synthesis. The critical parameter contributing to the film morphology was revealed to be the holding position of the reaction solution during deposition. In addition to this improvement, the SrRuO3 bottom elec

Far-infrared transmittance and reflectance of PbTiO3, PbZr0.53Ti0.47O3 and PbZr0.75Ti0.25O3 thin films deposited by a sol-gel technique on sapphire substrates were measured between room temperature and 650 degrees C. The spectra were fitted with a classical oscillator model to calculate the dielectric response. Polar-mode parameters are more accurate than data on bulk ceramic materials and are in good agreement with them. An analysis of the soft-made behaviour and comparison with the low-frequency permittiv

In this paper, we report on the performance of microwave phase shifters implemented on sol-gel derived Ba0.3Sr0.7TiO3 (BST) thin films. Coplanar waveguide (CPW) phase shifters, loaded-line phase shifters, and reflection-type digital phase shifters have been realized on a single alumina substrate covered with a 300nm-thick BST film. The performances of different types of phase shifting cells are compared. It is shown that the optimally designed digital phase shifters have better performance although the digi

For micromechanical applications, piezoelectric PbZrTO3 (PZT) thin films have been deposited on metallised Si3N4/SiO2 layers on Si wafers. Films with compositions near the morphotropic phase boundary (x=0.53) were prepared at 600°C using a multitarget, in- ...

The Bit formation using atomic force microscopy (AFM) was studied on 270-nm-thick < 111 > preferentially oriented Pb(Zr0.4Ti0.6)O-3 (PZT) films prepared by the sol-gel process. To minimize the cantilever-sample capacitive farce interaction, the experiment was carried out at or near the sample edge. Bit formation was investigated by calculating the electric field in AFM-tip/PZT film/bottom electrode configuration. It was found both experimentally and theoretically that:the bit size is linearly dependent on t

Two all-fiber wavelength tunable devices, one utilizing thermal tuning and a second based on strain tuning, have been produced by combining resistive Ti/Pt and piezoelectric ZnO fiber coatings with fiber Bragg gratings (FBGs). The Ti and Pt coatings with thicknesses of 40 and 300 nm, respectively, were deposited by sequential magnetron sputter deposition. ZnO fiber coatings with a thickness of 18 mu m were deposited by dual magnetron reactive sputtering. Joule heating of the Ti/Pt fiber coating was employed

A strong influence of ferroelectric polarization on d.c. conduction has been observed in PZT thin films with Pt electrodes. It is shown that the current-voltage response taken for measuring times of hundreds of seconds at room temperature is controlled by the crossover from the transient to steady-state conduction regime. In the transient regime the current flowing against the initial direction of the ferroelectric polarization is higher than that flowing in the reverse direction. In the steady-stare regime

Dielectric properties of single crystals of LAGaO3 have been measured at low frequencies as well as in the microwave region over a wide temperature range. Measurements performed on two crystal orientations, viz. (001) and (I 10), show dielectric anomalies at a transition near 145-degrees-C. Dielectric anisotropy below, but not above, 145-degrees-C confirm the previously reported orthorhombic symmetry at room temperature and rhombohedral symmetry above 145-degrees-C. Domain wall motion which arises as a resu

Ordered patterns of highly compliant ferroelastic domains have been created by use of tensile strained epitaxial Pb(Zr, Ti)O-3 thin films, of very low defect density, grown on DyScO3 substrates. The effect of 180 degrees switching on well-ordered a/c 90 de ...

The properties of Pb1-xCaxTiO3 (x=0-30) thin films for applications in point-detectors and arrays can be further improved ii porous, low-dielectric constant layers are being Used. Both 2-methoxyethanol and 1,3-propanediol based solution precursors were used for spin-coating platinized Si3N4/SiO2/Si wafers. The heating-rate during the final anneal was observed to be the controlling parameter for the evolution of either dense or porous microstructures, Low temperature crystallization of the perovskite phase (

We report the thermodynamic potential for single-domain (110) thin films epitaxially grown on dissimilar cubic substrates. Using different sets of paraelectric phase elastic compliance coefficients of PbTiO3 single crystal, calculated from the experimental ...

We present piezoresponse force microscopy measurements on individual integrated potassium niobate (KNbO3) nanowires. The devices consist of KNbO3 nanowires on SiO2 substrates being mechanically clamped and electrically biased by lithographically defined me ...

Nava Setter

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Preparation and characterization of KNbO3 ceramics

Optical fibers with patterned ZnO/electrode coatings for flexural actuators

Relation between Intrinsic Microwave and Submillimeter Losses and Permittivity in Dielectrics

Interferometric measurements of electric field-induced displacements in piezoelectric thin films

Size effect in ferroelectrics: Competition between geometrical and crystalline symmetries

Microwave phase shifters based on sol-gel derived Ba0.3Sr0.7TiO3 ferroelectric thin films

Electric-field-induced orthorhombic to rhombohedral phase transition in [111](C)-oriented 0.92Pb(Zn1/3Nb2/3)O-3-0.08PbTiO(3)

Charge relaxation at the interfaces of low-voltage ferroelectric film capacitors: Fatigue endurance and size effects

Ferroelectric properties of an epitaxial lead zirconate titanate thin film deposited by a hydrothermal method below the Curie temperature

Far-infrared dielectric response of PbTiO3 and PbZr1-xTixO3 thin ferroelectric films

Microwave phase shifters based on sol-gel derived Ba0.3Sr0.7TiO3 ferroelectric thin films

Pb(Zr,Ti)O3 thin films by in-situ reactive sputtering on micromachined membranes for micromechanical applications

Quantitative analysis of the bit size dependence on the pulse width and pulse voltage in ferroelectric memory devices using atomic force microscopy

Wavelength tunable fiber Bragg grating devices based on sputter deposited resistive and piezoelectric coatings

Effect of ferroelectric polarization on current response of PZT thin films

Dielectric-Properties of Lanthanum Gallate (Lagao3) Crystal

Compliant ferroelastic domains in epitaxial Pb(Zr, Ti)O-3 thin films

Electrical properties and microstructural evolution of porous Pb1-xCaxTiO3 pyroelectric thin films

Single-domain (110) PbTiO3 thin films: Thermodynamic theory and experiments

Piezoresponse force microscopy on doubly clamped KNbO3 nanowires