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In the present paper the phenomena predicted in [2] for substances with FE and AFE phases coexisting is experimentally shown for Pb(Mg 1/3 Nb 2/3 )O 3 and Pb(B′ 1/2 B′′ 1/2 )O 3 -type compounds. Special attention is paid to analysis of their phase diagrams. The influence of external factors on the properties of these substances is considered. It is shown that all peculiarities in the behaviour of the substances in question are described on the basis of phase transitions between FE and AFE states. [ABSTRACT FROM AUTHOR]

In a semi-review paper, the fundamentals of the vibronic (pseudo Jahn-Teller) theory of ferroelectricity in perovskite crystals of ABO3 type, its main achievements and significant applications, are given. The theory is derived from first principles. First, the pseudo Jahn-Teller effect (PJTE) is introduced and shown to be the only source of polar instability that triggers the spontaneous polarization of the crystal. The driving force of the PJTE is added covalency by distortion, which is essentially of local (chemical) origin. Then, the earlier more qualitative, but physical transparent results in application of the PJTE theory to ABO3 perovskites are presented, followed by the rigorous formulation in terms of Greens' functions theory. The form of the adiabatic potential energy surface (APES) for the metal B sites with eight equivalent minima, obtained analytically, is confirmed by DFT calculations, and its parameter numerical values were estimated for BaTiO3. It explains the occurrence of the three ferroelectric and one paraelectric phases, and order-disorder transitions between them as due to temperature dependent gradual overcome of the consecutive barriers between its eight equivalent minima. The theoretical treatment of the phase transitions is carried out in the mean-field approximation yielding near-to-experimental Curie temperatures. An important further development of this theory was reached more recently, for the first time revealing the role of spin in ferroelectric polarization of perovskites with the electronic dn configuration of the B ion. It was shown that, subject to the PJTE, not only d0 configurations may be unstable to produce ferroelectricity ("the d0 mystery"), but some other specific dn configurations with unpaired electrons may be dipolar active too, the crystal being thus both magnetic and ferroelectric (multiferroic). The necessary conditions for such multiferroicity are formulated for the whole n = 0,1,...10 variety of perovskites, and it is shown to be different in the two (or more) possible spin arrangements of the same ion, high-spin or low-spin for n = 3, 4, ...7. In conditions of spin crossover this leads to a magnetic-ferroelectric crossover that can be manipulated by external perturbations, including electric magnetization, already realized experimentally. A novel chapter is opened in application of the vibronic PJTE theory to important problems of materials science by analyzing the interaction of the ferroelectric perovskites with external perturbations. For the paraelectric phase of BaTiO3 with local dynamic-polar instability, any external electric field, strain, or stress violates the equivalency of the eight minima of the APES, quenching the polar dynamics, thus contributing an orientational polarization (like in polar liquids). It increases the permittivity, flexoelectricity, electrostriction, and external pressure effects by several orders of magnitude, confirmed experimentally. The theory explains also the formation of polar nanoregions and laxor properties in the paraelectric phase as due to the "local drops formation" when two phases may coexist locally (which is not possible in displacive theories where the formation of a polarized phase requires long-range interaction). A significant part of the paper is devoted to discussion and comparison of the vibronic PJTE theory of ferroelectricity with other theories and empirical data. It is shown that a series of experimentally observed specific properties of perovskite ferroelectrics encounter fundamental difficulties in attempt to explain their origin by means of displacive theories. This is related to the B ion being (instantly) polar displaced along the trigonal axis in all the phases, the order-disorder character of the phase transitions, the role of the spin of the B ion in the ferroelectric polarization, the strong dependence of ferroelectricity and multiferroicity on the chemical composition, the giant effects in interaction with external perturbations, the formation of polar nanoregions in nonpolar phases leading to relaxor behavior, etc. All these unique properties of perovskite ferroelectrics follow directly from the vibronic (PJTE) theory. [ABSTRACT FROM AUTHOR]

In this paper, microstructural, ferroelectric and magnetic properties of multiferroic composite system (1-x) Ba0.5Sr0.5TiO3(BST) – (x) Ni0.4Co0.2Zn0.4Fe2O4(NCZF), where x = 0.1, 0.2, 0.3, 0.4 molar ratio have been studied. Grains of NCZF are larger in size and more symmetrical in comparison to BST grains. Overall grain size of BST grains in the composite samples decreases with increase in NCZF content. Polarization vs Electric Field (P-E) loops of the composite samples are unsaturated. The values of remanant polarization of the composite samples increase with increase in NCZF content. The composite samples possess saturated M-H loops with the values of remanant and saturation magnetization increases with increase in NCZF content. [ABSTRACT FROM AUTHOR]

In the present paper the phenomena predicted in [1] for substances with coexisting FE and AFE phases coexistence is experimentally shown. The examples of PZT-based solid solutions are investigated. The solid solutions for which FE and AFE states have equal or close energy stability possess the following experimental properties: - a high degree of (paraelectric) PE phase transition diffuseness; - an essential dispersion of permittivity in the region of diffuse maximum of the dependences ℇ′(T) and ℇ′′(T) and fulfilment of the Fogel-Fülcher law; - an increase of the measuring AC field amplitude E 0 leads to a linear decrease of T′ m and to an increase of ℇ′(T′ m ); the tangent of T′ m (E 0 ) dependence decreases with an increase of AC field frequency; - the presence of effects which point to the existence of polar phase domains at temperatures essentially higher than T′ m and T′′ m ; - dependence of their properties on the sample's history; - a long-duration relaxation. [ABSTRACT FROM AUTHOR]

Solution for BaTiO3was prepared via sol-gel route in this paper. Ceramic fibers of BaTiO3were then obtained by gel-spinning technique with the solution. FTIR spectra of the samples of fibers were characterized. TG-DTA spectra of the gel fibers were also conducted by a thermal analyzer. Different sintering conditions were performed, in order to obtain ceramic fibers with better ferroelectric and piezoelectric properties. The crystal structures of the samples were identified with XRD. The microstructures of the ceramic fibers were observed with SEM, Meanwhile, ferroelectric and piezoelectric properties of the BaTiO3ceramic fibers were characterized by using of a workstation measurement system, with the remnant polarization of 9.41 μC/cm2, coercive field of 3.13 kV/cm, piezoelectric constant of 172 pC/N and mechanical-electrical parameter of 0.56. [ABSTRACT FROM AUTHOR]

Dielectric properties of 2,3,6,7,10,11-hexahydroxytriphenylene tetrahydrate crystallites are examined in this paper. We observe a first order, order-disorder phase transition at a temperature of 251 K. The frequency dependence revealed four relaxation regions, where two relaxations follow the Arrhenius law with activation energy of 300 meV. Our investigation shows the experimental data below the phase transition to follow the Curie-Weiss law, however, ferroelectric ordering is not observed. [ABSTRACT FROM AUTHOR]

Silver nano particles have been widely used as catalyst for chemical industry. However, the catalytic efficiency of the silver has been limited by the aggregation of the silver, as the active sites are only located on the surface of the catalyst particles. In this paper we report the surface aggregation dynamics of silver on different ferroelectric polarization surface and temperature dependent behaviors. Meanwhile, reducing the particle size to obtain the dispersed morphology of silver was discussed by the dissipative particle dynamics method and density functional theory. The surface with upward polarization provides more electrons to the silver, which is responsible for the dispersed morphology of the silver. [ABSTRACT FROM AUTHOR]

This paper presents the design and modeling of micro-electromechanical systems (MEMS) on the ternary ferroelectric compounds (PZT) based by using finite element model (FEM) simulation. The conceptual framework establishes five steps to perform the critical analysis: design a novel structure, define the failure mechanisms under the given conditions, analyze different vibrations, analyze the operation principle, and detect resonance modes. In addition, MEMS failure modes were analyzed under different scenarios and the obtained results discussed. [ABSTRACT FROM AUTHOR]

Microwave characterisation of dielectric materials is vital to implement the material in communication devices and circuits. The microwave characterisation parameters are the dielectric constant, loss tangent, Q0 × f0, temperature coefficient of frequency and temperature coefficient of permittivity. This paper examines the microwave characterisation data of four different dielectric materials. From several experiments on different dielectric materials, it has been concluded that the concept of using Q0 × f0 and temperature coefficient of frequency, as a material property will not reflect on material's fundamental behaviour. On the other hand, it has been interesting to note that the temperature coefficient of permittivity of a material is a constant irrespective of the measurement technique and hence it is a material parameter. The studies on temperature dependent permittivity will reveal the knack of a material to operate as a frequency stable circuit or device. [ABSTRACT FROM AUTHOR]

The paper reviews the results of our studies concerning the ferroelastic domain structure in the crystals exhibiting superprotonic conductivity. We would like to show the ferroelastic domain structure and its temperature behaviour in solid acids which belong to the family of crystals with a general formula MxLiyHz(XO4)(x + y + z)/2 (M = Rb,K,Cs,NH4; X = S and Se). For the majority of crystals, which belong to that family, the transition to the phase with high proton conductivity is simultaneously the ferroelastic-paraelastic one. However, this does not apply to all crystals of the family. Therefore, a question arises about the role of the phenomenon of ferroelasticity in the superprotonic phase transition. Depending on x,y and z, there are different groups of crystals. Our paper presents the results of temperature evolution of ferroelastic domain pattern at ferroelastic-superprotonic phase transitions as well as at other structural phase transitions, which appear in different crystal groups. [ABSTRACT FROM AUTHOR]

This paper reviews the spontaneous polarization of ferroelectric ceramics and its variations with applied electric field, stress and temperature, especially at induced phase transitions. Normally, there are two kinds of field dependence of the induced polarization, the linear and nonlinear dependence. In this paper the nonlinear relationship will be emphasized. The application of these ceramics for underwater transducers, shock wave power generators, pyroelectric energy converters and pyroelectric voltage transformers are listed. [ABSTRACT FROM AUTHOR]

This paper is devoted to the analysis of effective electromechanical properties and their maxima in 0-3-type composites based on (1 - x)Pb(Mg1/3Nb2/3)O3 - xPbTiO3 single crystals. It is shown that the electromechanical interaction between the single-crystal and polymer components with the anisotropy of their piezoelectric coefficients e33(n)/|e31(n)| ≥ 5 results in relations d33* ≈ e33*s33*E, g33* ≈ h33*s33*D, and kt* ≈ k33* for the electromechanical constants. These relations hold in a wide range of volume fraction and aspect ratio of the spheroidal inclusions in the 0-3 composite. An increase in the maximum values of different effective parameters is expected by forming a system of oblate air pores in the matrix. [ABSTRACT FROM AUTHOR]

Recently a theoretical model of the polarization modulated and layer undulated (B7) structure in the systems formed by bent-core (bow-shaped) molecules was presented. In contradiction to the general expectation the model suggests that polarization splay is possible only when the molecules are tilted with respect to the layer normal, i. e. when the chiral symmetry of the system is broken. In this paper we present a detailed stability analysis of the tilted and the nontilted structure with respect to polarization modulation and show, that polarization modulation in the nontilted phase is not possible because the system has no possibility to relieve the stress in the domain walls, neither by bending the layers nor by reducing the smectic order. [ABSTRACT FROM AUTHOR]

Bacteriophage T4 is a virus that attacks bacteria by a fascinating mechanism involving a natural microactuator. In this paper we give a theory for this microactuator that explains the deformations observed and is capable of giving quantitative information on the forces produced and the changes in free energy that occur. The theory suggests a route to man-made synthesis of this actuator (“biomolecular epitaxy” (BME)) and some interesting experiments that could be done on synthesized sheets. [ABSTRACT FROM AUTHOR]

Tunable ferroelectric ceramic capacitors have shown great promise in reducing the size, weight, and power (SWAP) of traditional varactor-based devices. Ferroelectric devices fabricated from Barium Strontium Titanate (BST) have been demonstrated in the laboratory and are just now becoming available for commercial narrowband applications. This paper presents some of the tradeoffs in designing a small form factor (SFF), easily manufacturable, broadband tunable filter utilizing high volume, low-cost BST devices. Development status for filters that cover the 225 MHz to 2.7 GHz frequency range with superior narrowband performance, low in-band insertion loss, and high out-of-band rejection that is directly applicable to the stringent requirements of Joint Tactical Radio System (JTRS) Cluster 5 Software Defined Radio (SDR) is also presented. These Manufacturing Readiness Level (MRL) 4 filters currently provide a 50% reduction in size over traditional approaches, and future short-term plans promise further reductions in unit production cost (UPC) and SWAP. [ABSTRACT FROM AUTHOR]

The contact-type scanning nonlinear dielectric microscopy (SNDM) can measure the distribution of linear and nonlinear dielectric properties of insulators with sub-nanometer resolution. SNDM, however, has tip-abrasion problem and this problem is one of the obstacles for the high quality image. In this paper, in order to improve SNDM, we propose a non-contact scanning nonlinear dielectric microscopy (NC-SNDM) which focused on the nonlinear dielectric signal for controlling the non-contact condition. With NC-SNDM technique, topographic and SNDM images were obtained successfully. [ABSTRACT FROM AUTHOR]

This paper describes the electrical properties of the CSD-derived ferroelectric PZT thin films on the oxide electrode of LaNiO 3 (LNO), which can improve the electrical fatigue for the PZT thin film. We successfully control the orientation of the resulting LNO thin film electrode by the molecular design of the precursor solution to control the orientation of the PZT thin film with a MPB composition on the LNO. As a result, PZT/LNO thin film capacitors exhibited superior electrical properties with no fatigue, not only for remanent polarization but also for piezoelectric and dielectric properties. [ABSTRACT FROM AUTHOR]

A SPICE-based model of an n-channel ferroelectric field effect transistor has been developed based on both theoretical and empirical data. This model was used to generate the I-V characteristic of several logic gates. The use of ferroelectric field effect transistors in memory circuits is being developed by several organizations. The ability of FFETs to have different characteristics depending on the initial polarization can be used to create logic gates. These gates can have properties not available to standard CMOS logic gates, such as memory, reconfigurability and memory. This paper investigates basic properties of FFET logic gates. [ABSTRACT FROM AUTHOR]

Besides the high electrostriction in the relaxor P(VDF-TrFE-CFE) terpolymers, the high dielectric constant (> 50) and high breakdown field lead to a high electric energy density (∼10 J/cm³), which is attractive for the high efficiency charge storage capacitors. This paper presents charging and discharging behavior, as well as the discharged energy density as a function of the field. The field dependence of the polarization response and the polarization saturation at very high field result in a nearly linear increase of the discharged energy density with field. For the field dependent polarization response in the low to medium field range, Rayleigh's law has been introduced in the past to describe the field dependent behavior (with loss) in this field range. We examine the relationship between the Rayleigh's law and the complex dielectric constant notation used widely in the scientific and engineering community and show that a modified complex notation can describe the field dependent dielectric response with loss in the low and medium field range quite well. [ABSTRACT FROM AUTHOR]

There has been extensive research activity since the discovery of fatigue free La-doped Bi 4 Ti 3 O 12 films on Pt electrodes. These films show superior ferroelectric properties and require a lower deposition temperature than the previously discovered SrBi 2 Ta 2 O 9 . Substitution of Bi by lanthanide elements other than La is of interest due to change in the magnitude of the structural distortion in the perovskite block, thereby, changing the remanent polarization. In this paper we discuss the doping of bismuth titanates with other lanthanide elements (Nd, Sm). The films were prepared by spin coating on Pt coated Si substrates. Structural characterization was performed by X-ray diffraction followed by ferroelectric characterization. [ABSTRACT FROM AUTHOR]

The ferroelectromagnet ceramics Pb(Fe0.5Nb0.5)O3 ( PFN) has been synthesized by solid state reaction technique. The measurements of the dielectric constant and loss as a function of temperatures and frequencies determined the relaxor ferroelectric behavior of this compound. The X-ray diffraction pattern shows the phase purity and the SEM images of fractured surface demonstrate the granular properties of the materials. In this paper, we study the magnetic field effect on the dielectric properties of PFN by measuring the dielectric constant and loss at different applied magnetic fields and different temperatures. [ABSTRACT FROM AUTHOR]

Investigation of mesoscopic inhomogeneities caused by the coexistence of FE and AFE phases is carried out in PLLZT solid solutions Pb1-x(Li½La½)x (Zr1-y Ty)O3 with x = 0.1 and 0.15, in which the energy difference between FE and AFE states is small. A weak distinction in free energy leads to the coexistence of the said phases domains at temperatures lower than the point of paraelectric phase transition In the discussed PLLZT solid solutions equivalent crystallographic sites are occupied by ions differing in the size. In the vicinity of the interphase border a process of ions segregation takes place. In the present paper, development of the process of "stratification" of the solid solutions in the course of time is studied. The said process is shown to be entirely completed in the course of 100-120 h. [ABSTRACT FROM AUTHOR]

The paper presents synthesis of (1-x)PMN-(x)PT (PMN-PT) near morphotropic phase boundary (MPB) i.e. for x = 0.25, 0.31, 0.33 and 0.35, using hydroxide co-precipitation method. Further, PMN-PT compositions under investigation were systematically characterized for density, structural, morphological, dielectric and ferroelectric properties. X-ray diffraction data reveals single phase formation of PMN-PT. The scanning electron microscopy (SEM) images were recorded and used to understand morphology of the samples. In present study, it was noted that the PMN-PT composition with x = 0.25 exhibits the maximum value of dielectric constant (ϵ) and saturation polarization (Pmax) amongst the PMN-PT compositions under investigation. [ABSTRACT FROM AUTHOR]

Sodium metavanadate has pyroxene-type one dimensional VO4-tetrahedral chains, which is analogous to the SiO4-chains in Bi2SiO5. Although it is known to undergo ferroelectric phase transition, its mechanism has not been clarified. This paper shows the spectroscopic results of simultaneous measurement of Raman/Brillouin scattering by utilizing ultra-narrowband holographic notch filters. The spectroscopic anomalies accompanying to the phase transition were observed for the first time in both Raman and Brillouin regimes. [ABSTRACT FROM AUTHOR]

In this paper we report on the investigation of longitudinal ultrasonic wave attenuation, velocity and ultrasonically induced piezoelectric voltage in P(VDF-TrFE) composites with fillers of conductive carbon nanotubes (CNT). Moreover, temperature dependences of ultrasonic attenuation in the composites were shown to be sensitive to thermal cycling over the ferroelectric phase transition. [ABSTRACT FROM AUTHOR]

In this paper, we established the origin of the experimentally observed topological instability representing the change of the plane domain wall shape by formation of so-called “fingers” during fast polarization reversal of the ferroelectric capacitor. By means of a simplified model we show that the topological instability of the domain wall can be attributed to retardation of the bulk screening of residual depolarization field. [ABSTRACT FROM PUBLISHER]

The paper first introduces the basic physics behind perovskite multiferroics. Then the recent progress on simple, complex perovskites, and manganites are briefly reviewed. The review discloses two important directions on achievement multiferrocity in perovskite: pay with strain engineering and adjust octahedral deformation. The authors also suggest that specific issues like leakage current and characterization platforms are also very important for the study of multiferroics. [ABSTRACT FROM PUBLISHER]

Nature has always amused us; sometimes it holds us in awe and sometimes it leaves us spellbound with its mysterious and inscrutable ways of working. The most significant and fundamental understanding of materials observed today is based on their constituent elements and position of the elements in the periodic table; which decides their property, behavior, reactivity and affinity with other elements. Given this primary aspects what comes secondary is the specificity or the multiplicity of functions that can be achieved from a material. In the present era, there is an incredible and massive increase in the number of functional materials to meet the ever-increasing need of electronic devices and their miniaturization. Functional materials have carved a special niche for itself in the field of material science. This review is exclusively intended to highlight and satiate the academic curiosity of novices about functional aspects of ferroelectric materials. It explores the various intricate and inherent principles and mechanisms which underpins the functional dimensions of ferroelectric materials. Ferroelectrics span a huge fraction of functional materials. Phenomenon like photovoltaic effect in ferroelectric materials, ferroelectric emission of electrons and their multifaceated applications are also discussed. Low dimensional ferroelectrics and their multifunctional prospects are also briefly covered in this review. It also includes brief idea of ferroelectric meta-materials, dielectric super-capacitors and its advantage over other preexisting ones. It is mostly informative and resourceful in providing multifunctional aspects of ferroelectrics. This review assures researchers who are genuinely interested in broadening their information base along with getting a fresh perspective into this emerging field of ferroelectrics as functional materials. [ABSTRACT FROM AUTHOR]

The concept of local ferroelectricity discussed in this paper belongs to the emerging field of ultrathin multiferroics. The idea of the ferroelectric polarization associated with the domain walls in magnets proposed by V.G. Bar'yakhtar et al. more than thirty years ago has recently got experimental evidence including electric field driven magnetic domain wall motion and electric field induced Stark shift in the single molecule microscopy. The special attention is paid here to the magnetoelectric properties of dislocation in stripe domain structure (i.e. the stripe domain heads) that differ considerably from the ones of straight domain wall segments. It is shown that the electric field induced displacement of the domain wall can be increased by an order of value with external constant magnetic field. [ABSTRACT FROM PUBLISHER]

Editorial. Focuses on the ferroelectrics journal containing papers presented at the seventh Russia-Cis-Baltic-Japan Symposium (RCBJSF-7) on ferroelectricity, held in Saint Petersburg, Russia on June 24-28, 2002. Institutes that organised the symposium; Key topics included in presentations at the convention; Schedule of the next symposium on ferroelectricity.

The article honors professor Julio A. Gonzalo, a condensed matter physicist, and acknowledges his contributions in the field of ferroelectricity and other phenomena. He carried out experimental work in ferroelectric physics and physics of phase transitions including valuable theoretical contributions to fundamental aspects. Further, Gonzalo has published about 200 scientific papers and five scientific books related to ferroelectricity.

The year 2020 marks hundred years since the watershed discovery of the phenomenon of ferroelectricity although at that time its importance was hardly realized. We provide a historical account of this event and its impact in terms of new materials discovery, novel fundamental physics concepts and technological applications on a decadal basis. We emphasize how ferroelectrics and the broader class of ferroics enriched our understanding of not only a wide variety of functional materials including multiferroics but also numerous device concepts and even a slew of topological defects these materials can harbor. Finally, we touch upon the current as well as future research topics in this ever growing and fecund area of interdisciplinary science. [ABSTRACT FROM AUTHOR]

One of the negative effects of ferroelectric applications, particularly for electrocaloric effect (ECE) applications, is temperature hysteresis (ΔTHyst). Temperature hysteresis is the difference between the temperatures corresponding to the maximum dielectric permittivity in heating and cooling modes. The value of ΔTHyst is commensurate with the value of the ECE temperature change. The ECE is a phenomenon in which a material shows a reversible temperature change under an applied electric field. The aim of this work is to study the possibilities of temperature hysteresis reduction by varying the ceramic sintering temperature, changing the stoichiometry of BaxSr1-xTiO3 solid solutions, and changing the rate of the heating-cooling cycle. [ABSTRACT FROM AUTHOR]

We report the preparation and characterization of vanadium substituted four-layer Aurivillius compound Bi5Fe1.5V0.5Ti2O15 using spin coating method. Ferroelectricity in the prepared films are confirmed from the well saturated polarization vs electric field (P-E) loops having remnant polarization (2 Pr) around 12.94 µC/cm2 at room temperature. In addition, low temperature P-E measurements show a decrease in Pmax and 2 Pr, which is attributed to the stabilization of defect dipole complexes and domain pinning, as seen in bismuth-based ferroelectrics. Additionally, this decrease in polarization is accompanied by an increase in imprint, confirming the presence of defect dipoles manifested as internal fields. [ABSTRACT FROM AUTHOR]

Tunability of ferroelectric complex oxides is achieved by applied bias voltage. Many applications require usage of relatively low voltage which is achievable by using a ferroelectric thin-film. Recently developed dielectric metamaterials were implemented in bulk and in thick films. Metamaterials are resonant structures. The frequency range of 0.1–1.5 THz is of special interest for such applications as non-destructive evaluation of materials and detection of chemical and biological hazards. This paper numerically investigates the possibility of a resonant effect in a thin-film ferroelectric metamaterial and the effects of increased dielectric constant and thickness on the thin-film's resonance frequency. [ABSTRACT FROM AUTHOR]

Effect of lower ionic radii (Na and Nd) substitution in A-site on the structure, dielectric, ferroelectric and piezoelectric properties of SrBi4Ti4O15(SBT) is investigated in this paper. The samples are prepared by solid state double sintering method and sol gel method based on pechini process. Substitution of smaller ions reduced the dielectric constant and remanent polarization values. But sol gel samples showed good dielectric and ferroelectric properties. A-site substitution has resulted in improved Curie temperature and piezoelectric properties. As a result, Na and Nd modified SBT ceramics are found to be excellent high temperature piezoelectric materials. [ABSTRACT FROM PUBLISHER]

In this paper scanning probe microscopy investigations of surface morphology and local ferroelectric properties of sol-gel deposited PZT thin films are presented. It is shown that the films have sufficiently low surface roughness about 2 nm and small grain size about 20 nm. Possibility of the film polarization by applying both positive and negative DC voltage between the SPM probe and the sample is demonstrated. Additionally, times of residual piezoresponse signal relaxation are measured and domain wall velocity for the PZT films is calculated. [ABSTRACT FROM AUTHOR]

Ferroelectricity and piezoelectricity are two of the common ferroelectric material properties, which have widespread observations in many biological systems, and these are referred to as biopiezoelectricity and bioferroelectricity. This paper presents a short overview of the main issues of piezoelectricity and ferroelectricity, their manifestation in organic, biological, and molecular systems. As a showcase of novel biopiezomaterials, the investigation of diphenylalanine (FF) peptide nanotubes (PNTs) is described by computational molecular modeling, as well by experimental AFM/PFM measurements. FF PNTs present a unique class of self-assembled functional biomaterials, owing to their wide range of useful properties, including nanostructural piezoelectric and ferroelectric properties. [ABSTRACT FROM AUTHOR]

This paper highlights the structural, dielectric and pyroelectric properties of two complex tungsten bonze ceramics (K2Pb2Pr2W2Ti4Nb4O30and K2Pb2Pr2W2Ti4Ta4O30) which were prepared by high temperature mixed oxide method. Room temperature X-ray structural analysis confirms the formation of the compounds in single phase. SEM micrographs show uniform distribution of densely packed rod like grains. Variation of dielectric parameters with temperature and frequency shows the phase transition at 350°C and 426°C for the respective samples. Temperature dependent hysteresis loop confirms the existence of ferroelectricity in the materials. The current variation with voltage at different temperatures shows the semiconductor like behaviour of the materials. The temperature dependent dc conductivity follows the Arrhenius equation, and reveals the negative temperature coefficient of resistance (NTCR) behaviour of the materials. The current (for a fixed voltage) variation with temperature shows that the materials have high pyroelectric co-efficient and figure of merit, thus making them useful for pyroelectric sensors. [ABSTRACT FROM AUTHOR]

In this paper we report the mechanism and nature of relaxor ferroelectric behavior in the environmental friendly lead free Barium Zirconate Titanate (BZT) system. A revised complete (Structure:Property) phase diagram of Ba(ZrxTi1-x)O3, with compositions 0.00≤ × ≤1.00 has been developed based on their electrical properties. Two different kinds of relaxor behaviors have been observed in the BZT system; one is dominated by polar Ti-rich regions and another by non-polar Zr-rich regions. All the BZT relaxor compositions are characterized by dielectric properties with and without bias, pyroelectric and thermal expansion measurements in the wide range of temperatures. The structure of the BZT compositions has been evaluated by XRD, Neutron diffraction study. Further the local structure of the BZT compositions has been probed by micro-Raman spectra. Although the global structure of BZT relaxors is cubic as observed in Neutron diffraction studies, the local symmetry is non-cubic as evident in the micro-Raman spectra of BZT relaxors as well as in their thermal strain measurement, dielectric and pyroelectric behavior. [ABSTRACT FROM PUBLISHER]

This paper is devoted to the problem of the electromechanical coupling of advanced composites based on relaxor-ferroelectric single crystals with large piezoelectric activity. A novel 0–3–0 PMN–0.33PT single crystal/porous araldite composite is considered as a material with large values of electromechanical coupling factors with a variable anisotropy. The role of physical and microstructural factors in achieving the considerable electromechanical coupling is discussed for 0–3–0 connectivity. [ABSTRACT FROM PUBLISHER]

In spite of a number of studies on the ferroelectricity of the isotope exchanged SrTi18O3, it has not been clarified yet why the spontaneous polarization P in the isotope exchanged SrTi18O3 is not parallel to [100]c as expected from the Slater mode but parallel to [110]c. In this paper it is shown that the dipole-dipole interaction between the rhombohedral polar clusters which exist from well above Tc is closely related to the formation of the P parallel to [110]c. The results are consistent with the appearance of the relaxational mode in the Raman spectra and suggest the existence of the order-disorder nature of this transition. [ABSTRACT FROM AUTHOR]

This paper proposed an application of Artificial Neural Network (ANN) to concurrently model ferroelectric hysteresis properties of Barium Titanate in both single-crystal and bulk-ceramics forms. In the ANN modeling, there are 3 inputs, which are type of materials (single or bulk), field amplitude and frequency, and 1 output, which is hysteresis area. Appropriate number of hidden layer and hidden node were achieved through a search of up to 2 layers and 30 neurons in each layer. After ANN had been properly trained, a network with highest accuracy was selected. Query file of unseen input data was then input to the selected network to obtain the predicted hysteresis area. From the results, the target and predicted data were found to match very well. This therefore suggests that ANN can be successfully used to concurrently model ferroelectric hysteresis property even though the considered ferroelectrics are with different domains, grains and microscopic crystal structures. [ABSTRACT FROM AUTHOR]

The National Aeronautics and Space Administration (NASA) is developing high-tolerance, radiation-hardened electronics for missions in and beyond Low Earth orbit. Ferroelectric-based electronics are highly viable candidates for these electronics because of their inherent radiation-hardened property. Since standard memory devices are prone to damage caused by radiation, ferroelectric memory may provide the needed radiation-tolerance. To test the effectiveness of ferroelectric random access memory (FRAM) in Low Earth orbit, a 512 K Ramtron FRAM will be flown on a Low Earth orbit satellite that will be launched by NASA. This paper discusses the advantages of ferroelectric electronics and outlines the Low Earth orbit ferroelectric memory test experiment. [ABSTRACT FROM AUTHOR]

This paper describes an automated-measurement system of ferroelectric hysteresis loops, which was developed in LabView environment based on Virtual Instrument. The system provides a function obtaining nonlinear polarization current from measured current data, which is important for properly estimating ferroelectricity of a dielectric, especially for one with high electric loss. In addition, the relationship between nonlinear polarization current density and external electric field of a ferroelectric reveals more information which is helpful for researches of polar order and/or ferroelectric characteristics. [ABSTRACT FROM AUTHOR]

This paper investigated the ferroelectric and dielectric properties of Sm-doped BaTiO3 sintered in different atmosphere. The influence of variable doping concentration on microstructure, ferroelectric and dielectric properties was studied. The results showed that the dielectric-temperature curve of Sm-doped BaTiO3 was smoother than that of pure BaTiO3. And tunability of Sm-doped BaTiO3 was smaller than that of pure BaTiO3. Dielectric constant of the samples sintered in nitrogen was smaller than that of samples sintered in air. The hysteresis loop displayed that ferroelectric polarization decreased with Sm doping. [ABSTRACT FROM AUTHOR]