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Thin PZT films are one of the prominent materials in majority of chips and devices due to their ferroelectric properties. The main goal of this paper is analysis of the crystallographic orientations along the micro crystals of thin PZT (PbZr0.53 Ti0.47 O3) film with 10 % La content. For this purpose, we applied transmission electron microscopy in the diffraction mode, bright- and dark-field modes, the extinction bend contours method, and the stereographic projection. The main goal of the present paper is to study the microstructure and, in particularly, patterns of extinction bend contours of the sample of the thin PZT film with 10 % La content. [ABSTRACT FROM AUTHOR]

Experimental study on stopping power of ferroelectric Tryglycine Sulphate (TGS) single crystal for 24.779 MeV protons was carried out as a function of the temperature of TGS with an accuracy of 0.05%. The stopping power of the TGC crystal shows broad valleys in ferroelectric region when the proton beam is moving along the ferroelectric b-axis (010). The fluctuations with peak-peak variation of 0.3% - 0.6% for proton beam near the Curie temperature TC is observed. This variation in the ferroelectric region cannot be contributed to the dielectric constant of the medium. The electric field and the localized temperature due to passage of proton beam may cause the switching and pining of the domains. The domain switching time τs depends on the transverse electric field and sample thickness. The thermal spike model is used to estimate the increase in the localized temperature due to passage of 24.779 MeV Protons in ferroelectric TGS crystal. In this paper, the experimental method of measuring stopping power of TGS crystal for proton beam, interpretation of the results in terms of (i) increase in localized temperature of the crystal sample using thermal spike model, (ii) the transverse electric field developed in the crystal sample and (iii) the domain switching time to account the observed experimental fluctuations in stopping power of TGS crystal for proton beam is discussed. [ABSTRACT FROM AUTHOR]

The paper considers several examples of non-Debye dielectric response in complex heterogeneous media. The percolation phenomenon and Cole-Cole relaxation in disordered matter are discussed in detail. The models enable us to establish the relationship between the parameters of dielectric relaxation broadening, structural properties of the media and transport features of charge carriers in the considered systems. In addition, the origins of “strange kinetic” phenomena and the specific features of relaxation kinetics in systems with different kinds of confinements are discussed in the paper. In contrast to the usual Arrhenius or Vogel-Fulcher-Tammann patterns, a quite unusual non-monotonic dependence of relaxation time versus temperature is observed in such systems. Based on the free volume concept, a model for this type of kinetics was illustrated by several particular examples: water confined in porous glasses and doped ferroelectric crystal. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

The probability density function (PDF) for the lead ion in PbMg[sub 1/]3Nb[sub 2/3]O[sub 3]. crystal was calculated in the frames of the spherical layer model, using earlier published experimental data. Temperature evolution of the radial part of the PDF ρ(R) is analyzed in the temperature region 293K

Recent developments on micro-structuring of ferroelectric crystals, such as LiNbO3, have opened up new possibilities for several devices in nonlinear and electro optics. In this paper, after describing the basics of LiNbO3 based integrated electro-optic modulators, we will show how techniques such as etching, domain inversion and thin film processing can be used to realize new geometries which can take the performance to unprecedented levels. In particular we will report recent results on the use of domain inversion on a micron scale to tailor and improve the electro-optic response of LiNbO3 waveguide modulators, showing that these applications for domain inversion techniques might be even more important and commercially valuable than those in nonlinear optics (e.g. quasi-phase-matched optical parametric devices). With respect to standard single-domain structures, larger bandwidths and lower driving voltages can be obtained, thus achieving figure of merits for the electro-optic response that are up to 50% larger. As a demonstration, a ∼2 V switching voltage modulator with bandwidth much larger than 10 GHz was made possible by placing the waveguide arms of the Mach-Zehnder interferometer in opposite domain oriented regions. The modulator could be driven in a single drive configuration with inexpensive low voltage drivers, e.g. SiGe based, typically used for electro-absorption devices. Along the way we had developed a full wafer, up to 4″, poling process of LiNbO3 waveguide substrates without the need of any grinding of the back face after Ti indiffusion, thus achieving high yield (>90%) for the fabricated modulator chips. [ABSTRACT FROM AUTHOR]

This paper addresses the question of “how large is large enough for a crystallite to be a three dimensional Bravais lattice?” Based on the premise that the ratio of the bulk volume to that of the volume of the unit cell for a given material should determine the transition to a large molecule, it is proposed that for values of the ratio < 106 crystallites can be considered as large molecules. The universality of this criterion has been established by examples from magnetism, optics, ferroelectrics and superconductivity. It is expected, due to the wide variety of materials considered, that other classes of inorganic materials would also obey this rule leading to a quantitative definition for a nanocrystal or nanostructure. © 2003 American Institute of Physics [ABSTRACT FROM AUTHOR]

Up to now, classical 'water' loads have been used for low power testing of ITER ICRH prototype or mock-up antennas . A fair description of the antenna frequency response is obtained excepted for the phasing (0 π 0 π). High dielectric loads are requested to improve the antenna response in the low frequency band [1]. In view of laboratory testing, dummy loads are also required to have efficient wave spatial attenuation to avoid standing waves and to minimize load volume. In this paper, barium titanate ceramic powders mixed with water are shown to exhibit very attractive electromagnetic properties. Coupling performance of one triplet of the ITER ICRH antenna to such kind of loads is numerically investigated. The radiated wave attenuation into the load is also characterized. In spite of its frequency dispersion, 'barium titanate' loads are shown to allow the characterization of the full scale triplet frequency response on a scaled-down mock-up. [ABSTRACT FROM AUTHOR]

This paper discusses a number of recently developed all optical and optically assisted methods for ferroelectric domain engineering in lithium niobate and their impact on the micro-structuring of this optical ferroelectric crystal. Optical radiation is used to change the response of lithium niobate crystals to externally applied electric field encouraging or inhibiting ferroelectric domain inversion in a simultaneous or latent manner. Optically assisted poling processes have the advantage of producing ferroelectric domains with arbitrary shapes free from crystal symmetry restrictions which is very important for fabricating surface micro/nano-structures in this material. [ABSTRACT FROM AUTHOR]

Landau-Devonshire theory is a phenomenological theory of ferroelectrics. In this paper a detailed discussion of the application of this theory to ferroelectric films is given; also the interaction of the film with incident electromagnetic radiation is discussed via the Landau-Khalatnikov equations of motion. In particular the role of optimization in the theory is emphasized. It is shown that two important areas to which optimization is relevant are the minimization of the free-energy density, an essential part of the Landau-Devonshire theory, and to the way in which the equations of motion are solved. For the latter it turns out that it is better to work in real variables rather than the complex variables that are convenient to introduce into the formalism prior to the numerical work when dealing with harmonic waves. [ABSTRACT FROM AUTHOR]

Aim of the present work is to investigate the Random telegraph Signal (RTS) in a Floating Gate based memory cell (Flash memory) when the device is rapidly and periodically turned “on” and “off”. In particular, the low-frequency noise dependence as a function of frequency of the large-signal excitation has been experimentally explored. The results have been discussed in relation with the average time constants of trap. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

In this paper, we present a microscopic model for heterogeneous ferroelectric and an order parameter for relaxor phase. We write a Landau theory based on this model and its application to ferroelectric PbFe1/2Ta1/2O3 (PFT) and antiferroelectric NaNbO3:Gd. We later discuss the coupling between soft mode and domain walls, soft mode and quasi-local vibration and resulting susceptibility function. © 2003 American Institute of Physics [ABSTRACT FROM AUTHOR]

Diffuse neutron scattering is a valuable tool to obtain information about the size and orientation of the polar nanoregions that are a characteristic feature of relaxor ferroelectrics. In this paper, we present new diffuse scattering results obtained on Pb(Zn[sub 1/3]Nb[sub 2/3])O[sub 3] (PZN for short) and (1-x)Pb(Zn[sub 1/3]Nb[sub 2/3])O[sub 3]-xPbTiO[sub 3] (PZN-xPT) single crystals (with x=-4.5 and 9%), around various Bragg reflections and along three symmetry directions in the [100]-[011] zone. Diffuse scattering is observed around reflections with mixed indices, (100), (011) and (300), and 'along transverse and diagonal directions only. No diffuse scattering is found in longitudinal scans. The diffuse scattering peaks can be fitted well with a Lorentzian function, from which a correlation length is extracted. The correlation length increases with decreasing temperatures down to the transition at T[sub c], first following a Curie-Weiss law, then departing from it and becoming flat at very low temperatures. These results are interpreted in terms of three temperature regions: 1) dynamic polarization fluctuations (i.e. with a finite lifetime) at high temperatures, 2) static polarization reorientations (condensation of polar nanoregions) that can still reorient as a unit (relaxor behavior) at intermediate temperatures and 3) orientational freezing of the polar nanoregions with random strain fields in pure PZN or a structural phase transition in PZN-xPT at low temperatures. The addition of PT leads to a broadening of the diffuse scattering along the diagonal ([111]) relative to the transverse ([100]) direction, indicating a change in the orientation of the polar regions. Also, with the addition of PT, the polar nanoregions condense at a higher temperature above T[sub c]. [ABSTRACT FROM AUTHOR]

This paper examines the domain patterns and its relation to the macroscopic electromechanical behavior of ferroelectric solids using a theory based on homogenization and energy minimization. The domain patterns in different crystalline systems are classified, the spontaneous strain and polarization for single crystals and polycrystals are characterized, and the optimal texture of polycrystals for high-strain actuation is identified. The results also reveal why it is easy to pole PZT at compositions close to the ‘morphotropic phase boundary.’ © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

A systematic study of the temperature dependence of superlattice reflections in the reciprocal space of a single crystal Pb(Mg[sub 1/3]Nb[sub 2/3])O[sub 3] (PMN) was performed using anomalous x-ray scattering technique. Our studies confirm the existence of the two types of nanoregions in PMN: a) chemically ordered nanodomains, and b) polar nanodomains formed by short-range correlated ionic displacements. No detailed temperature dependence of these superlattice reflections has been reported in the past. From monitoring the superlatttice reflections corresponding to polar nanodomains (i.e. α spots) over the temperature range 15K-800K, we found freezing temperature (T[sub f]) of correlated atomic displacements was near 200 K. In contrast, chemically ordered nanodomains, which give rise to F type superlattice peaks, exhibited spherical shape over the entire temperature interval 15-800 K. This leads us to suspect that chemically ordered regions might be different and independent of polar nanodomains. In this paper we explain the contributions of different atomic displacements to α and F superlattice reflections in PMN. Correlation and competition between Pb displacements and the tilting of oxygen octahedra network are presented to understand the microstructural origin of the relaxor ferroelectric behavior. [ABSTRACT FROM AUTHOR]

For the present study, La substituted PZT ceramics having compositional formula Pb1-3x/2LaxZr0.65Ti0.35O3 were prepared by conventional solid state method. La content was varied from x = 0 to 0.03 in the steps of 0.01. XRD analyses of all the samples were done and were found to have single phase with rhombohedral structure. In this paper, we are reporting the variation in ferroelectric properties of Pb1-3x/2LaxZr0.65Ti0.35O3 by varying La content. P-E hysteresis loops were recorded using P-E loop tracer based on Sawyer- Tower circuit for all the samples at 20 Hz. Increase in coercive field (Ec), remanant polarization (Pr), saturation polarization (Ps) and squareness ratio (Pr/Ps) was observed with increase in x. [ABSTRACT FROM AUTHOR]

Potassium dihydrogen phosphate crystal (KDP, KH2PO4) and Rubidium dihydrogen phosphate crystal (RDP, RbH2PO4) both are ferroelectric crystals and has been broadly studied because of their many properties in the area of ferroelectrics. In the present work, we have added third and fourth order anharmonic interactions and some other interaction terms in our modified Hamiltonian and have employed Green's function technique to elucidate temperature dependence of soft mode frequency, dielectric constant and loss tangent in both crystals. For a suitable temperature range, Curie-Weiss behaviour can be seen in our result. Also, for validation, we have compared our results with experimental researchers. [ABSTRACT FROM AUTHOR]

We present our recent results on the development and experimental testing of advanced dielectric materials that are capable of supporting the high RF electric fields generated by electron beams or pulsed high power microwaves. These materials have been optimized or specially designed for accelerator applications. The materials discussed here include low loss microwave ceramics, quartz, Chemical Vapor Deposition diamonds and nonlinear Barium Strontium Titanate based ferroelectrics. [ABSTRACT FROM AUTHOR]

Developing an innovative PS-DAVLL (Polarization Switching DAVLL) method of frequency stabilization, which used a ferroelectric liquid crystal cell as quarter wave plate, rubidium cell and developed ultra-stable current source, allowed to obtain a frequency stability of 10-9 (frequency reproducibility of 1,2·10-8) and reductions in external dimensions of laser source. The total power consumption is only 1,5 Watt. Because stabilization method used in the frequency standard is insensitive to vibration, the semiconductor laser interferometer was built for measuring range over one meter, which can also be used in industry for the accurate measurement of displacements with an accuracy of 1[μm/m]. Measurements of the VCSEL laser parameters are important from the standpoint of its use in laser interferometry or vibrometry, like narrow emission line ΔνFWHM = 70[MHz] equivalent of this laser type and stability of linear polarization of VCSEL laser. The undoubted advantage of the constructed laser source is the lack of mode-hopping effect during continuous work of VCSEL. [ABSTRACT FROM AUTHOR]

The aim of this paper is to study the nonlinear dissipative effects of ferroelectric polycrystals based on firm thermodynamics principles. The developed micro-mechanically motivated model is embedded into an electromechanically coupled finite element formulation. In this framework, each domain is represented by a single finite element, and initial dipole directions are randomly oriented so that the virgin state of the particular bulk ceramics of interest reflects an un-poled material. Thermodynamically consistent energy criterion based on Gibbs free energy is adopted for the initiation of domain switching processes. The so-called grain-boundary effects, that is the constraint imposed by the surrounding grains on a grain at its boundary is incorporated in this model by means of micro-macromechanically motivated concept. In the expression for the driving force, an additional term is incorporated based on the change in Gibbs free energy of the neighboring grains for the particular switching domain/grain of interest. To study the overall bulk ceramics behavior, straightforward volume averaging techniques are applied. The simulated numerical results show appreciable improvement in modeling the nonlinear response for ferroelectrics subjected to various loading aspects compared with the experimental data from the literature. [ABSTRACT FROM AUTHOR]

Recent developments on micro-structuring of ferroelectric crystals, such as LiNbO3, have opened up new possibilities for several devices in nonlinear and electro optics. In this paper, after describing the basics of LiNbO3 based integrated electro-optic modulators, we will show how techniques such as etching, domain inversion and thin film processing can be used to realize new geometries which can take the performance to unprecedented levels. In particular we will report recent results on the use of domain inversion on a micron scale to tailor and improve the electro-optic response of LiNbO3 waveguide modulators, showing that these applications for domain inversion techniques might be even more important and commercially valuable than those in nonlinear optics (e.g. quasi-phase-matched optical parametric devices). With respect to standard single-domain structures, larger bandwidths and lower driving voltages can be obtained, thus achieving figure of merits for the electro-optic response that are up to 50% larger. As a demonstration, a ∼2 V switching voltage modulator with bandwidth much larger than 10 GHz was made possible by placing the waveguide arms of the Mach-Zehnder interferometer in opposite domain oriented regions. The modulator could be driven in a single drive configuration with inexpensive low voltage drivers, e.g. SiGe based, typically used for electro-absorption devices. Along the way we had developed a full wafer, up to 4″, poling process of LiNbO3 waveguide substrates without the need of any grinding of the back face after Ti indiffusion, thus achieving high yield (>90%) for the fabricated modulator chips. [ABSTRACT FROM AUTHOR]

In recent years, bismuth layer structured ferroelectrics (BLSFs) have been given much attention because some materials, such as Ba2Bi4Ti5O18, are excellent candidate materials for nonvolatile ferroelectric random access memory (FRAM) applications. BLSFs are also better candidates because of their higher Curie points. Recently, we have carried out computer simulation in atomic scale in order to predict the energies associated with the accommodation of aliovalent and isovalent dopants (Pb2+, Al3+, Ga3+, In3+, Ta5+) in the Aurivillius structure of Ba2Bi4Ti5O18. In this work, the predicted stable phases were synthesized using solid state reactions and their products then were characterized using powder X-ray diffraction method. The cell parameters were determined using Rietveld refinement in orthorhombic system with space group of B2cb. The cell parameters for Ba2Bi4Ti5O18 doped with Pb2+, Al3+, Ga3+, In3+, Ta5+ were a = 5.5006(6) b = 5.4990(5) c = 50.5440(7) Å; a = 5.5012(4) b = 5.4986(8) c = 50.5449(7) Å; a = 5.5006(3) b = 5.4999(3) c = 50.5437(9) Å; a = 5.5007(4) b = 5.4989(7) c = 50.5446(6) Å; and a = 5.5000(5) b = 5.4995(8) c = 50.5436(6) Å. Results from the ferroelectric properties measurement for Ba2Bi4Ti5O18 doped with Pb2+, Al3+, Ga3+, In3+, Ta5+ were Pr = 16.7 μC/cm2, Ec = 35.1 kV/cm; Pr = 15.9 μC/cm2, Ec = 33.8 kV/cm; Pr = 15.6 μC/cm2, Ec = 34.2 kV/cm; Pr = 15.3 μC/cm2, Ec = 34.0 kV/cm; Pr = 16.9 μC/cm2, Ec = 35.6 kV/cm. [ABSTRACT FROM AUTHOR]

We study the growth process of ferroelectric materials by kinetic Monte Carlo simulations. An ionic model with long-range Coulomb interactions is used to model the relaxor single crystals. The growth is characterized by thermodynamic processes involving adsorption and evaporation, with solid-on-solid restrictions. An algorithm is developed in order to simulate growth under such a model, for which existing formalism of the kinetic Monte Carlo algorithm is inadequate. We study the growth rates and the order structure of the grown crystals as a function of temperature, chemical composition, and growth orientation. Tests of our algorithm on NaCl gave good results. Preliminary results on growth in Ba-based heterovalent binaries showed 1:2 ordering along the [111] direction over limited scales. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

In this paper the possibility of observing chaotic behaviour in an electronic circuit including a nonlinear ferroelectrics has been investigated. The ferroelectrics constitutes the medium interposed between the two plates of a capacitor, and is obtained by successive vapour deposition of Strontium, Tantalum and Bismuth on Platinum substrates in small areas. The device is characterized by a nonlinear hysteretic behaviour observed by estimating the output voltage by using a Sawyer-Tower configuration. Different circuits showing chaos and based on hysteretic behaviour of the nonlinearities have been reported in literature. In particular, in the circuit reported in [1] the nonlinearity consists of a piecewise linear resistor, only the two tracts with positive slope are effectively involved in the dynamics and an hysteretic behaviour switching between these two linear segments of the nonlinearity can be addressed as responsible of the emergence of iperchaos in the circuit. Starting from the chaos generator reported in [1], the following dimensionless equations have been developed: where f(x) is the nonlinearity due to the hysteresis of the ferroelectrics capacitor. The functional f(x) constitutes a simple model of the ferroelectrics device and is defined by two functions (the upper curve and the lower curve based on experimental data on the ferroelectrics). Chaotic solutions of system (1) were searched for, by performing numerical integration with respect to different values of the parameters. Finally, the circuit implementing equations (1) has been realized. Experimental results show that for a suitable range of parameter a chaotic attractor emerges. Fig. 1 shows the projection of the attractor onto the phase plane x1-x2. The paper addresses the possibility of exploiting the rich dynamics of ferroelectrics hysteresis to obtain new chaotic attractors with low cost circuits. © 2003 American Institute of Physics [ABSTRACT FROM AUTHOR]

The complex oxides are very fascinating materials because of the interesting structures and wide variety of properties associated with them such as superconductors, ideal semiconductors, magnetic materials, catalysts, ferroelectrics, dielectrics, electrode materials for batteries, fuel cells and so on. The Structural and electronic properties of Lnn+1NinO2n+2 (Ln=La, Ce, Pr, Pm; n=3) are investigated by performing the full-potential linearized augmented plane wave method. The results related to La4Ni3O8 are in excellent agreement with the reported data. While, the results for Ce4Ni3O8, Pr4Ni3O8 and Pm4Ni3O8; are reported for the first time. We expect that the obtained results will be very useful for future experimental research. [ABSTRACT FROM AUTHOR]

Ferroelectrics have received intense attention due to its great application potential in RAM devices and new types of sensors. The stability issue of ferroelectric domain in lead meta niobate (PbNb2O6) single crystal for its manipulation using electric field at nano scale control on the geometrical dimensions of domain is reported, which is highly desirable for both applications and fundamental study. The analytical parameters like critical radius of nucleation of domain (rc), domain wall energy (α), critical energy of nucleation (ωc), geometrical dimensions of domain for this peculiar ferroelectric crystal are calculated and condition of back-switching on removal of applied electric field is discussed. [ABSTRACT FROM AUTHOR]

This article is devoted to the synthesis and investigation of thin ferroelectric and magnetostrictive layers as potential constituents of composite multiferroics. We chose alloy Fe10Ni90 as magnetostrictive medium. The magnetic anisotropy and magnetoelastic properties of films Fe10Ni90 are investigated. It is shown that they can be significantly modified with a variation in the thickness of the samples in the range 40-80 nm. We chose polyvinylidene fluoride(PVDF) as ferroelectric medium. Its films were obtained by spin-coating and had a thickness of ~200 nm. The analysis of the crystallinity and phase composition of the films are completed. It is established that the factors influencing on these properties are the thickness of the films and the conditions for their heat treatment. The magnetic properties of the PVDF / Fe10Ni90 film structures with optimized parameters of layered components are determinate. [ABSTRACT FROM AUTHOR]

We perform Monte-Carlo simulations of a realistic model of the perovskite multiferroic manganites RMnO3 (R = Gd, Tb, Dy) in order to obtain the ground state phase diagram. It is shown that the dynamic Dzyaloshinskii-Moriya interaction plays a crucial role in stabilizing the state with coexisting incommensurate magnetic and ferroelectric order. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

We discuss theoretically the isotope effects on phase transition temperature Tc and generalized force constant kf in perovskite-type ferroelectric. We give the result of our calculation on the reduced force constant of the soft optic phonon with quantum-mechanical electron-phonon interaction model at finite temperature. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

An extended two sublattice pseudospin lattice coupled mode model by adding third and fourth order phonon an harmonic interaction terms as well as external electric field term is considered for (CH2NH2COOH)3 H2SO4 crystal. With the help of double-time temperature dependent green's function method expression for shift width, soft mode frequency, dielectric constant loss tangent and Acoustic attenuation are derived. By fitting model values in the theoretical expressions. Temperature and electric field dependence of soft mode frequency, dielectric constant and loss tangent are calculated. The theoretical result compare well with experimental results of Bye et al [ferroelectrics, 4(1972)253]. [ABSTRACT FROM AUTHOR]

An extended two sublattice pseudospin lattice coupled mode model of Chaudhuri et al [Phys.Rev.338 (1988) 689] by adding third and fourth-order phonon anharmonic interactions terms is considered for triglycine sulphate (CH2NH2COOH)3H2SO4 crystal and its isomorphs. With the help of double-time temperature dependent Green's function method, expressions for shift,width, soft mode frequency, dielectric constant and loss tangent are derived. By fitting model values in the theoritical expressions, temperature dependence of soft mode frequency, dielectric constant and loss tangent are calculated. The theoretical results compare well with experimental results of Aravazhi et al [Ferroelectrics200 (1997) 279.] [ABSTRACT FROM AUTHOR]

Ba0,25Sr0,75TiO3 (BST) thin films has been deposited on a Si (100) p-type substrate by chemical solution deposition (CSD) method followed by spin coating technique (at 3000 rpm rotational speed for 30 seconds) and annealing process at the temperature around 850° C for 15 hours. The films show a maximum optical absorption at green light. An I-V investigation on the films results in agreement that the thin films have a photodiode characteristic. Electrical conductivity of the BST thin films is in the range of 2.79×10-7 to 5.3×10-7 S/cm, it is the range of semiconductor materials. The electrical conductivity and photocurrent increase when the light intensity increases from 1000 to 6000 Lux. A BST thin film has been utilized as a light meter in an ATMega8535 microcontroller since it is sensitive with a light intensity change. Base on calibration and validation curves, a measurement using this microcontroller results in comparable light intensity values with that result from a standard instrument. [ABSTRACT FROM AUTHOR]

This work reports on the development of a Lead Lanthanum Zirconate Titanate (PLZT) bulk ferroelectric poled ceramic structure as a Ferroelectric Sensor (FS) sensor. The ceramic was implanted during its fabrication with a platinum (Pt) wire which works as an internal electrode. The ceramic was then submitted to experimental setups in order to validate and determine the Pt-wire mechanical and optical effects. This FS was also mounted on a finger splint in order to measure the blood flow that results from the pulsations of blood occurring with each heartbeat. Also this FS was used as opacity sensor allows performing 2D scanning and generating 3D graphics or images of opacity depending on the percentage of opacity of the sample. On the other hand the FS works as ECG modulator, piezoelectric microbalance, photodetector, high power signal mixer, temperature monitor, vibration sensor for industrial motors, and other important applications. [ABSTRACT FROM AUTHOR]

Barium strontium titanate (Ba0.8Sr0.2TiO3) nanocrystalline thin film fabricated by a modified sol-gel process was crystallized at low temperature 550 °C. The microstructure displayed a polycrystalline nature with average nanograin size of 11 nm. The BST thin film annealed at 550 °C show good dielectric properties. The BST thin films show a diffuse type phase transition. The room temperature dielectric constant and dissipation factors are 310 and 0.03 at 100 kHz, respectively. The capacitance-frequency curves reveal that the film shows typical frequency dispersion at low frequency. The ferroelectric nature of the BST thin film was indicated by butterfly-shaped C-V curves. The effect of temperature on C-V characteristic of the BST thin films has been investigated. The sample shows paraelectric nature well above the transition temperature as indicated by the absence of butterfly-shaped C-V curves. [ABSTRACT FROM AUTHOR]

We present a theoretical analysis of dielectric loss of antiferroelectric liquid crystals by using a discrete phenomenological model which incorporates the effects such as steric, van der Waals, chirality, quadrupolar, nearest-neighbouring (NN) and next-nearest-neighbouring (NNN) layers interactions. The effect of chirality on dielectric loss of chiral smectic liquid crystal phases is significant; thus, analytical and numerical results on dielectric loss in terms of eigen frequencies of the phase and amplitude modes are presented. [ABSTRACT FROM AUTHOR]

Ferroelectric materials show remarkable physical behaviors that make them essential for many devices and have been extensively studied for their applications of nonvolatile random access memory (NvRAM) and high-speed random access memories. Although ferroelectric ceramics (polycrystals) present ease in manufacture and in compositional modifications and represent the widest application area of materials, computational and theoretical studies are sparse owing to many reasons including the large number of constituent atoms. Macroscopic properties of ferroelectric polycrystals are dominated by the inhomogeneities at the crystallographic domain/grain level. Orientation of grains/domains is critical to the electromechanical response of the single crystalline and polycrystalline materials. Polycrystalline materials have the potential of exhibiting better performance at a macroscopic scale by design of the domain/grain configuration at the domain-size scale. This suggests that piezoelectric properties can be optimized by a proper choice of the parameters which control the distribution of grain orientations. Nevertheless, this choice is complicated and it is impossible to analyze all possible combinations of the distribution parameters or the angles themselves. Hence we have implemented the stochastic optimization technique of simulated annealing combined with the homogenization for the optimization problem. The mathematical homogenization theory of a piezoelectric medium is implemented in the finite element method (FEM) by solving the coupled equilibrium electrical and mechanical fields. This implementation enables the study of the dependence of the macroscopic electromechanical properties of a typical crystalline and polycrystalline ferroelectric ceramic on the grain orientation. [ABSTRACT FROM AUTHOR]

The ferroelectric phase transition in Sn2P2S6 crystals is a result of a strong non-linear interaction between vibrational modes with Bu and Ag symmetry which determines the three-well shape of the potential. Such multistability is reflected in spectroscopic and thermodynamic characteristics of the lattice anharmonicity. By analysing the quasielastic and Brillouin light scattering, heat capacity, volume thermal expansion and heat transport temperature behavior, it was found that negative contribution of the optic modes to the Gruneisen coefficient in a wide temperature interval of the ferroelectric phase is special characteristic of the investigated ferroelctrics. [ABSTRACT FROM AUTHOR]

Multiferroics: the multifunctional materials exhibit the entwined nature between the two distinct phenomena of ferroelectricity and ferromagnetism, which allow them to utilize for novel device concepts that would not be attainable by either ferroelectric or ferromagnetic materials. Magnetic and ferroelectric materials are time-honoured research subjects which have led to new discoveries, both scientific and technological. Multiferroic compounds are the source of magnetoelectric (ME) effects that are strong enough to induce magnetic or electric phase transitions, thus exerting ME phase control. The giant response can be generated by the presence of exceptionally large magnetic and/or electric fields in matter, which are the result of the long-range ordering. In this sense the ME effect in multiferroics is ‘large’ if the ME contribution corresponding to the free energy of the system is large. Due to their interesting physical, chemical, and mechanical properties, these materials have been used to realize a vast number of devices ranging from giant devices like electrical transformers to tiny devices like sensors, used in integrated circuits or as storage devices. Furthermore, these materials are likely to offer new kinds of devices and functionality, because of their size-dependent physical and chemical properties, which have motivated a lot of current research activity in the area of ferroelectric and magnetic materials. In particular, advances in atomic and nanoscale growth and characterization techniques have led to the production of modern ferroelectromagnetic materials that reveal a range of fascinating phenomena. These phenomena derived from the fact that electrons have spin as well as charge, giving an extra level of complexity to the physics, and an extra degree of freedom in device design. Magnetoelectric coupling between electric and magnetic order parameters has been theoretically predicted, and there is intense interest in its implementation in device architectures taking advantage of these properties. Multiferroics may be in the form of single-phase, exhibit mulitferroicity generally at low temperatures and in a composite form as a product property of a composite phase consisting of a magnetostrictive and a piezoelectric material. Hence, the search continues for new single-phase and composite multiferroic materials that exhibit high ordering temperatures, high coupling constant, low dielectric loss and low leakage current. [ABSTRACT FROM AUTHOR]

Lead lanthanum titanate (Pb0.9La0.1TiO3) and lead calcium titanate (Pb0.9Ca0.1TiO3) ferroelectric ceramics were prepared by semi-chemical route. Both the materials were calcined at 600°C for pure perovskite phase formation. Grain size ∼1 and 0.5μm were observed for PCT 90/10 and PLT 90/10 ceramics, respectively. Room temperature value of [variant_greek_epsilon]r and tanδ at 10 kHz in PLT 90/10 material were found to be 835 and 0.035. [ABSTRACT FROM AUTHOR]

In this work we present a characterization of a ferroelectric liquid crystal modulator and its performance optimization as an optical switch. We present a procedure to characterize the orientation of the liquid crystal layer and its change with the applied voltage. Then we illuminate the modulator with white light and analyze the transmitted light with a portable spectro-photometer. The chromatic dispersion of the phase shift introduced by the modulator is obtained from the spectral intensity of the transmitted light. Then we apply this result to evaluate the response as an optical switch both for white light and monochromatic laser light with different wavelengths. We show that it is possible to optimize the response of the modulator for wavelengths that are far from the design wavelength. For that purpose a quarter wave-plate is placed in front of the modulator. In this configuration the modulator is illuminated with elliptically polarized light, being the polarization ellipse selected to produce at the exit two states as close as possible to be orthogonal. [ABSTRACT FROM AUTHOR]

The relative current noise power spectral density S = SI(f)/I2 observed in organic semiconductors exhibits a maximum at the trap-filling transition between the ohmic and the space-charge-limited-current regime. The electrostatic conditions determining the crossover from ohmic to space-charge-limited transport at the trap-filling transition are here discussed. These arguments shed light on the need to adopt a percolative fluctuations model to account for the competition between insulating and conductive phases as the voltage increases. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

The present work establishes a finite element based solution for the rigorous homogenization problem to quantify the microstructural features such as crystallographic orientation and spatial distribution of domains on the global piezoelectric response of single-crystalline and polycrystalline ferroelectric materials. The crystal orientation dependences of the macroscopic electromechanical properties of single-crystal as well as polycrystalline ferroelectrics BaTiO3, and PbTiO3 are studied based on this method. Both the materials show large anisotropy in the piezoelectric strain djK in its single-crystal form. The homogenized electromechanical properties of polycrystalline system also exhibit significant anisotropic behaviours. An optimum texture, at which the piezoelectric response of both the polycrystalline material is maximised, is identified. Piezoelectric performance characteristics like the electromechanical coupling coefficients at various textures are evaluated for polycrystals of both the materials. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

In order to test a critical lateral dimension in two dimensional (2D) planar ferroelectric, epitaxial PbTiO3 discrete islands were fabricated by both lithography process and chemical solution deposition process with different lateral size. The evolution of 90° domain structures as a function of film thickness and lateral dimensions was characterized extensively by reciprocal space mapping using the Huber six-circle diffractometer of the synchrotron x-ray diffraction beam line at Pohang Light Source. This method is useful for considering a reciprocal lattice point that is tilted out of the growth plane and has many advantages for the investigation of imperfect heterostructures. As the pattern size decreases in micron scale, the substrate clamping effects is significantly reduced and thus the misfit strain in the films could be relaxed further. As the lateral size of patterns decreases to about 100 nm by e-beam lithography, the quite different domain structures were observed especially in the strain distribution as well as tilting of a-domains. The new type of a-domains appeared in the nanoscale PbTiO3 patterns in the center of the reciprocal space map of tilted PbTiO3 (100) that has been observed in the continuous films. These new a-domains are aligned along the substrate normal without the tilting angle required to maintain an a/c twin boundary relationship. Equilibrium domain structures in the PbTiO3 thin film islands are also analyzed by the finite element simulation and found to be consistent with the experimental observation. In the case of nano islands formed by chemical solution deposition, c-domain abundance increases as both size and thickness decrease identically, which implies that if the size can be reduced below a certain critical size there exists only single c-domain. Compared to the case of patterns with lateral dimension of 100 nm and thickness of 100 nm which has a tendency of reduced c-domain abundance due to the reduction of compressive strain, islands with thickness of 30 nm and 120 nm lateral size have larger c-domain abundance. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

X-ray diffraction has been conducted to study the microscopic-scale structures for 0.72Pb(Mg1/3Nb2/3)O3-0.28PbTiO3 relaxor ferroelectrics in a high external DC field during phase transition. Clear quasi-periodic structures were observed along <111> and <1-11> directions near Tc induced by the high external DC field. The formation of these periodic structures are interpreted as a type of Coulomb interaction among adjacent polar clusters. The cluster size was estimated to be 17nm. It was also found that the dominating interaction direction among clusters (periodic direction) were changeable among <111> and <1-11> as temperature changed. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

Fast switching (<10 nsec) measurement results on the recently developed BST(M) (barium strontium titanium oxide composition with magnesium-based additions) ferroelectric materials are presented. These materials can be used as the basis for new advanced technology components suitable for high-gradient accelerators. A ferroelectric ceramic has an electric field-dependent dielectric permittivity that can be altered by applying a bias voltage. Ferroelectric materials offer significant benefits for linear collider applications, in particular, for switching and control elements where a very short response time of <10 nsec is required. The measurement results presented here show that the new BST(M) ceramic exhibits a high tunability factor: a bias field of 40–50 kV/cm reduces the permittivity by a factor of 1.3–1.5. The recently developed technology of gold biasing contact deposition on large diameter (110 cm) thin wall ferroelectric rings allowed ∼few nsec switching times in witness sample experiments. The ferroelectric rings can be used at high pulsed power (tens of megawatts) for X-band components as well as at high average power in the range of a few kilowatts for the L-band phase-shifter, under development for optimization of the ILC rf coupling. Accelerator applications include fast active X-band and Ka-band high-power ferroelectric switches, high-power X-band and L-band phase shifters, and tunable dielectric-loaded accelerating structures. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

Description is given of a preliminary conceptual design for a tuner that employs a new ferroelectric ceramic that allows fast changes in coupling between the SRF acceleration structure of a linac and the external RF feeding line. The switching time of this device is in the range of a few microseconds. Utilization of this tuner is predicted to decrease Ohmic losses in the acceleration structure and thereby to reduce the power consumption of the linac. Using parameters of the TESLA-800 collider as an example, it is shown that it may be possible to reduce the ac mains power consumption by 12 MW, or about by 10%. The design of the tuner that is described allows reduced pulsed and average heating of the ferroelectric ceramics. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

We present results on a new ferroelectric material based on bulk low-loss BST (Barium-Strontium Titanium oxides) compounds especially developed for accelerator applications. We have demonstrated suitable nonlinear dielectric properties of this material that make it useful for switching and tuning RF accelerator components. The material exhibits a dielectric constant of 400–500 and tunability factor of 1.2. The best sample of those studied demonstrated a loss factor <4×10-3 at 35 GHz. Ferroelectric rings and substrates are key components required for electrically controlled switches and phase shifters for active pulse compressors for future linear colliders. A thin ferroelectric layer incorporated into a dielectric loaded accelerating structure allows compensation of any frequency shift caused by ceramic waveguide machining tolerances and dielectric constant heterogeneity. A tuning range of 1.1% has been demonstrated for an X-Band (11–13 GHz) dielectric accelerating structure. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

The mixed perovskite oxides KTa1-xNbxO3, or KTN, are a model system for studying ferroelectric behavior and phase transitions under pressure. Crystals with x > 0.1 exhibit ferroelectric soft-mode behavior and a sequence of phase transitions, while for x ≤ 0.02 a pressure-induced ferroelectric-to-relaxor crossover occurs. The system also exhibits a pressure-induced crossover from classical-to-quantum behavior ultimately leading to the complete suppression of the phase transition and the formation of a quantum paraelectric state. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

Principles and preliminary design for a microwave active pulse compressor using an electrically-controlled ferroelectric switch are presented. The design of an 11.4 GHz, 500 MW pulse compressor with a pulse width of about 40 nsec and a compression ratio of 10 is described. It is planned to test this compressor using the Omega-P/NRL X-band magnicon. © 2003 American Institute of Physics [ABSTRACT FROM AUTHOR]

Ferroelectric and ferroelastic phases with very low domain wall energies have been shown to form miniaturized microdomain structures. A theory of an adaptive ferroelectric phase has been developed to predict the microdomain-averaged crystal lattice parameters of this structurally inhomogeneous state. The theory is an extension of conventional martensite theory, applied to ferroelectric systems with very low domain wall energies. The cases of ferroelectric microdomains of tetragonal (FEt) symmetry are considered. It is shown that a nano-scale coherent mixture of microdomains can be interpreted as an adaptive ferroelectric phase, whose microdomain-averaged crystal lattice is monoclinic. The crystal lattice parameters of this monoclinic phase are self-adjusting parameters, which minimize the transformation stress. Self-adjustment is achieved by application of the invariant plane strain (IPS) to the parent cubic lattice, and the value of the self-adjusted parameters constitutes a mixture of the lattice constants of the parent and product phases. Experimental investigations of Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) and Pb(Zn1/3Nb2/3)O3-PbTiO3 (PZN-PT) single crystals confirm many of the predictions of this theory. © 2003 American Institute of Physics [ABSTRACT FROM AUTHOR]