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To make BNT-BT ceramics, in this study, we put amount of small BaTiO3 (BT) which has the characteristics of the ferroelectric and the tetragonal structure at the normal temperature in BNT. The temperature goes up very fast to the maximum, 100degC for first 3 minutes and then it is saturated. We can recognize from the P-E curve that much more generation of heat is accompanied the impressed electric...
Investigations in the development of lead-free piezoelectric ceramics have recently claimed properties comparable to that of PZT-based materials. In this work, the dielectric and piezoelectric properties of the various systems were contrasted in relation to their respective Curie temperatures. Though comparable with respect to TC, enhanced properties reported in the K,NaNbO3 family are the result...
The electric properties of bismuth-and sodium-modified barium titanate, Ba1-x(Bi1/2Na1/2)xTiO3 (BBNT) were studied as a lead-free PTC (positive temperature coefficient of resistivity) thermistor material usable over 130degC. Two semiconductorization processes and their electric properties are described. Lanthanum(La)-doped BBNT ceramics sintered in air still show dielectric behaviors, but Nb-doped...
Ferroelectric capacitors made from Ba0.5Sr0.5TiO3 (BST) are applied as varactors in tunable, high frequency circuit applications. In this context, a voltage-controlled oscillator (VCO) based on Colpitts architecture has been designed and implemented using discrete RF BJTs and tunable ferroelectric Capacitor. The tunable ferroelectric capacitor has been fabricated on quartz substrate with BST deposited...
(1-x)Pb(Sc0.5Ta0.5)O3-xPb(Zr0.52Ti0.48)O3 (PSTZT-100x) ceramics were prepared by using conventional oxide processing, and their piezoelectric and ferroelectric properties studied. The results of X-ray diffraction (XRD) suggest that PSTZT-100x ceramics formed a single-phase perovskite structure when 0.1lesxles0.8. The ceramics exhibit relatively good piezoelectric and ferroelectric properties: piezoelectric...
In this paper, we systematically present the physical and mathematical meanings of the parameters used in Burfoot et al.'s and Eiras et al.'s model. Based on our experimental results in (l-x)PFW-xPT relaxor system and the theoretically modelling results, it is shown that the parameter values in Burfoot et al.'s model and Eiras et al.'s model have not any variations after normalizing the maximum dielectric...
The anisotropy of polarization and strain behavior in textured Bi0.5(Na0.85K0.15)0.5TiO3 ceramics are investigated for lead-free piezoelectric ceramics actuators. The textured Bi0.5(Na0.85K0.15)0.5TiO3 ceramics are fabricated by reactive templated grain growth (RTGG) using plate-like Bi4Ti3O12 particles. RTGG[//] (sliced parallel to the casting direction) and RTGG[square] (sliced perpendicularly to...
We fabricated a new ferroelectric gate field-effect transistor memory (F-FET) with an intermediate electrode inserted between the ferroelectric capacitor (Cf) and the metal-oxide-semiconductor field-effect transistor (MOSFET) for writing data. The structure was a RuO2 top electrode/polycrystalline ferroelectric Pb(Zr0.52Ti0.48)O3 (PZT)/(Pt/RuO2) intermediate electrode/SiO2/Si substrate. The basic...
A PZT, Pb(Zr,Ti)O3 (40:60), ferroelectric layer has been successfully deposited onto a Al0.3Ga0.7N/GaN heterostructure with a 2DEG, two dimensional electron gas. Due to the chemical and temperature stability of AlGaN/GaN it was possible to implement the concept of field-effect transistor with ferroelectric gate. The high temperature processing conditions for PZT were optimised in order to grow highly...
We report in this paper, the fabrication process of surface acoustic wave (SAW) devices by direct writing using electron beam lithography on very high resistivity materials, and the frequency characterization of the high frequency devices realized using this technologic process. Various experimental parameters relative to lithography system, resist deposition and lift-off process were studied and...
Recording density, domain switching time and bit error rate were evaluated using a data storage system based on scanning nonlinear dielectric microscopy. Congruent lithium tantalate single crystals with the thickness less than 50 nm were used as recording media. Local domain switching was carried out by applying voltage pulse on the recording media using a conductive cantilever. Close-packed domain...
The temperature usage range of rhombohedral Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMNT) piezoelectric crystals is limited by the Curie temperature (TC) and further limited by the strongly curved morphotropic phase boundary (MPB). It is found in PMNT crystals that TC decreases or keeps constant at low dc bias and then increases with increasing field, while the ferroelectric-ferroelectric phase transition temperature...
This study is part of a new research program to develop fundamental understanding of the fracture and fatigue behavior of piezoelectric single crystals through the combination of computational and experimental approaches. In this work we present 1) experimental results on the creation of artificial surface defects in piezoelectric single crystals using a focused ion beam (FIB) system and 2) initial...
Barium strontium titanate has been targeted as one potential ferroelectric glass-ceramic for high energy density dielectric materials. Previous testing has shown that the dielectric constant of these materials was as high as 1000 and dielectric breakdown strength up to 800 kV/cm. This did not, however, result in exceptional energy density (~ 0.90 J/cm3). In order to increase overall energy density...
Modeling of electrostatic field distribution and energy storage in diphasic dielectrics containing high-permittivity BaTiO3 in a glass host has been carried out using analytical modeling based on the Maxwell Garnett (MG) mixing rule, and numerical simulations accomplished using boundary element method (BEM) method software. The field distribution was studied as a function of the dielectric contrasts...
The influence of the stress and orientation of a lead zirconate titanate (PZT) film on its piezoelectric properties was investigated. Preferentially (111) oriented PZT films were prepared on various substrates with different thermal expansion coefficient, such as stainless steel, alumina, magnesia, and silicon by the CSD method. Preferentially (100) oriented PZT films were also prepared on stainless...
The following topics are dealt with: capacitors and dielectrics; ceramic processing; epitaxial thin films; ferroelectric memory; lithium niobate and soft ferroelectrics; multiferroics; nonlinear dielectrics; non-Pb piezoelectrics; piezoelectric materials; single crystals; scanning probe techniques; thin film piezoelectrics and tunable microwave materials.
Our group has been investigating properties of nanostructured Barium Strontium Titanate (BST) thin-films for use in a number of microwave/millimetre wave applications in collaboration with the Air Force Research Laboratory. Currently, a ferroelectric varactor shunt switch which can be useful for low power, low voltage microwave/millimeterwave switching is under investigation. A coplanar waveguide...
Piezoelectric micro machined ultrasonic transducers (pMUT) are piezoelectric laminated plates operating at flexural modes. The pMUT's fabricated in this work contained a 4 ??m thick lead zirconate titanate (PZT) thin film deposited by a sol-gel technique, and exhibiting a permittivity of ??r=1200, and an effective transverse piezoelectric coefficient e31,f of 12 C/m2. A further optimization of the...
Tunable filters are critical size, weight, power, and cost (SWAP-C) enabling components for military radios: Joint Tactical Radios (JTRS), Weapons Data Link (WDL), Tactical Target Networking Technology (TTNT), and cognitive radios. The ability to tune (center frequency, bandwidth) and reconfigure (bandpass, notch) filters dynamically in the system allows agile communications. In this paper we will...
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