Showing papers on "Ferroelectricity published in 2000"
TL;DR: In this paper, the fundamental physics behind the scarcity of ferromagnetic ferroelectric coexistence was explored and the properties of known magnetically ordered ferro-electric materials were examined.
Abstract: Multiferroic magnetoelectrics are materials that are both ferromagnetic and ferroelectric in the same phase. As a result, they have a spontaneous magnetization that can be switched by an applied magnetic field, a spontaneous polarization that can be switched by an applied electric field, and often some coupling between the two. Very few exist in nature or have been synthesized in the laboratory. In this paper, we explore the fundamental physics behind the scarcity of ferromagnetic ferroelectric coexistence. In addition, we examine the properties of some known magnetically ordered ferroelectric materials. We find that, in general, the transition metal d electrons, which are essential for magnetism, reduce the tendency for off-center ferroelectric distortion. Consequently, an additional electronic or structural driving force must be present for ferromagnetism and ferroelectricity to occur simultaneously.
3,146 citations
TL;DR: It is shown that a large piezoelectric response can be driven by polarization rotation induced by an external electric field, and the computations suggest how to design materials with better performance, and may stimulate further interest in the fundamental theory of dielectric systems in finite electric fields.
Abstract: Piezoelectric materials, which convert mechanical to electrical energy (and vice versa), are crucial in medical imaging, telecommunication and ultrasonic devices. A new generation of single-crystal materials, such as Pb(Zn1/3Nb2/3)O3-PbTiO3 (PZN-PT) and Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT), exhibit a piezoelectric effect that is ten times larger than conventional ceramics, and may revolutionize these applications. However, the mechanism underlying the ultrahigh performance of these new materials-and consequently the possibilities for further improvements-are not at present clear. Here we report a first-principles study of the ferroelectric perovskite, BaTiO3, which is similar to single-crystal PZN-PT but is a simpler system to analyse. We show that a large piezoelectric response can be driven by polarization rotation induced by an external electric field. Our computations suggest how to design materials with better performance, and may stimulate further interest in the fundamental theory of dielectric systems in finite electric fields.
1,789 citations
TL;DR: In this paper, the authors describe a material, cubic CaCu 3 Ti 4 O 12, which exhibits a large dielectric response, the temperature-dependence of which has not been seen, to our knowledge, in any existing material.
1,006 citations
TL;DR: High resolution x-ray powder diffraction measurements on poled PbZr1-xTixO3 (PZT) ceramic samples have shown that for both rhombohedral and tetragonal compositions the piezoelectric elongation of the unit cell does not occur along the polar directions but along those directions associated with the monoclinic distortion.
Abstract: High resolution x-ray powder diffraction measurements on poled PbZr1-xTixO3 (PZT) ceramic samples close to the rhombohedral-tetragonal phase boundary (the so-called morphotropic phase boundary) have shown that for both rhombohedral and tetragonal compositions the piezoelectric elongation of the unit cell does not occur along the polar directions but along those directions associated with the monoclinic distortion. This work provides the first direct evidence for the origin of the very high piezoelectricity in PZT.
921 citations
TL;DR: In this paper, a detailed analysis of the detailed structure of the tetragonal and monoclinic PZT phases on a sample with $x=0.45--0.48$ for which the lattice parameters are, respectively,
Abstract: The perovskitelike ferroelectric system ${\mathrm{PbZr}}_{1\ensuremath{-}x}{\mathrm{Ti}}_{x}{\mathrm{O}}_{3}$ (PZT) has a nearly vertical morphotropic phase boundary (MPB) around $x=0.45--0.50.$ Recent synchrotron x-ray powder diffraction measurements by Noheda et al. [Appl. Phys. Lett. 74, 2059 (1999)] have revealed a monoclinic phase between the previously established tetragonal and rhombohedral regions. In the present work we describe a Rietveld analysis of the detailed structure of the tetragonal and monoclinic PZT phases on a sample with $x=0.48$ for which the lattice parameters are, respectively, ${a}_{t}=4.044$ \AA{}, ${c}_{t}=4.138$ \AA{}, at 325 K, and ${a}_{m}=5.721$ \AA{}, ${b}_{m}=5.708$ \AA{}, ${c}_{m}=4.138$ \AA{}, $\ensuremath{\beta}=90.496\ifmmode^\circ\else\textdegree\fi{},$ at 20 K. In the tetragonal phase the shifts of the atoms along the polar [001] direction are similar to those in ${\mathrm{PbTiO}}_{3}$ but the refinement indicates that there are, in addition, local disordered shifts of the Pb atoms of $\ensuremath{\sim}0.2$ \AA{} perpendicular to the polar axis. The monoclinic structure can be viewed as a condensation along one of the $〈110〉$ directions of the local displacements present in the tetragonal phase. It equally well corresponds to a freezing-out of the local displacements along one of the $〈100〉$ directions recently reported by Corker et al. [J. Phys.: Condens. Matter 10, 6251 (1998)] for rhombohedral PZT. The monoclinic structure therefore provides a microscopic picture of the MPB region in which one of the ``locally'' monoclinic phases in the ``average'' rhombohedral or tetragonal structures freezes out, and thus represents a bridge between these two phases.
738 citations
TL;DR: In this paper, the phase pure BiFeO3 was synthesized using the oxide mixing technique followed by leaching with dilute nitric acid, and X-ray diffraction pattern indicated that the sample is phase pure.
Abstract: The difficulties in synthesizing phase pure BiFeO3 are well known. In this letter we are reporting the optimized synthesis conditions for obtaining phase pure BiFeO3 ceramic. The oxide mixing technique followed by leaching with dilute nitric acid has been used for the synthesis. X-ray diffraction pattern indicated that the sample is phase pure. Scanning electron microscopy along with energy dispersive x-ray fluorescence analysis confirmed the chemical homogeneity of the sample. No segregation of the impurity phase in the matrix was detected. Moreover, Bi/Fe atomic ratio is observed to be ∼1. The ferroelectric transition of the sample at 836 °C has been detected by differential thermal analysis.
738 citations
TL;DR: Recent studies involve submicron films of aromatic and aliphatic polyureas prepared by vapor deposition polymerization in vacuum and the piezoelectricity of polyurethane produced by the coupling of electrostriction and bias electric fields.
Abstract: Electrets of carnauba wax and resin have exhibited good stability of trapped charges for nearly 50 years. Dipolar orientation and trapped charge are two mechanisms contributing to the pyro-, piezo-, and ferroelectricity of polymers. Since the 1950s, shear piezoelectricity was investigated in polymers of biological origin (such as cellulose and collagen) as well as synthetic optically active polymers (such as polyamides and polylactic acids). Since the discovery of piezoelectricity in poled polyvinylidene fluoride (PVDF) in 1969, the pyro-, piezo-, and ferroelectricity were widely investigated in a number of polar polymers, such as copolymers of vinylidene fluoride and trifluoroethylene, copolymers of vinylcyanide and vinylacetate, and nylons. Recent studies involve submicron films of aromatic and aliphatic polyureas prepared by vapor deposition polymerization in vacuum and the piezoelectricity of polyurethane produced by the coupling of electrostriction and bias electric fields. Gramophone pickups using a piece of bone or tendon were demonstrated in 1959. Microphones using a stretched film of polymethyl glutamate were reported in 1968. Ultrasonic transducers using elongated and poled films of PVDF were demonstrated in 1972. Headphones and tweeters using PVDF were marketed in 1975. Hydrophones and various electromechanical devices utilizing PVDP and its copolymers have been developed during the past 30 years. This paper briefly reviews the history and recent progress in piezoelectric polymers.
504 citations
TL;DR: A review of the literature on size effects in ferroelectric materials, with an emphasis on thin film perovskite ferroelectrics, can be found in this paper.
Abstract: ▪ Abstract This paper reviews the literature on size effects in ferroelectric materials, with an emphasis on thin film perovskite ferroelectrics. The roles of boundary conditions, defect chemistry, electrode interfaces, surface layers, and microstructure in controlling the measured properties of ferroelectric films, as well as the observed deviation from bulk properties are discussed. Examples of the manifestation of size effects in terms of the low and high field dielectric properties, the piezoelectric effect, and the leakage behavior of films are given.
482 citations
TL;DR: In this article, the relaxation time of BiFeO3 was estimated using the relaxation times of the intermediate compositions of the BaTiO3 mixture, and the authors showed that the capacitance observed is from the bulk of the sample.
Abstract: BiFeO3, when forming a solid solution with BaTiO3, shows structural transformations over the entire compositional range. Above 70 mole % of BiFeO3 the structure is rhombohedral and below 4 mole %, it is tetragonal. In between the structure is cubic. The ferroelectric TC decreases with increasing composition of BaTiO3 and a relatively small relaxation is observed. Impedance measurements showed a structural dependence and analysis of which has clearly shown that the capacitance observed is from the bulk of the sample. Relaxation time (τ) of BiFeO3 was estimated using the relaxation times of the intermediate compositions. Magnetization measurements showed field induced ferromagnetism. As the structure becomes cubic with increasing concentration of BaTiO3, paramagnetism sets in, as evidenced by the electron spin resonance spectra.
463 citations
TL;DR: In this article, a misfit strain-temperature phase diagram of SrTiO3 films is developed taking into account the existence of two coupled instabilities (antiferrodistortive and ferroelectric) in this crystal.
Abstract: A Landau-Ginsburg-Devonshire-type theory is used to describe the mechanical substrate effect on equilibrium states and phase transitions in SrTiO3 epitaxial thin films. The misfit strain-temperature phase diagram of SrTiO3 films is developed taking into account the existence of two coupled instabilities (antiferrodistortive and ferroelectric) in this crystal. It is shown that SrTiO3 films remain paraelectric down to 0 K only in a narrow range of small negative misfit strains between -2 x 10(-3) and -2.2 x 10(-4). Outside this "paraelectric gap," he 2D clamping and straining of the film by the substrate leads to the appearance of ferroelectricity in SrTiO3 films. The temperature of the ferroelectric transition increases rapidly outside the aforementioned misfit strain range.
461 citations
TL;DR: The electron emission from ferroelectrics (FEE) is an unconventional electron emission effect as discussed by the authors, which is a tunneling emission current which screens uncompensated polarization charges, generated by a deviation of macroscopic spontaneous polarization from its equilibrium state under pyroelectric effect, piezoelectric effect, or polarization switching.
Abstract: Electron emission from ferroelectrics (FEE) is an unconventional electron emission effect. Methods of FEE excitation are quite different compared to classic electron emission from solids. Two kinds of FEE have been observed, “weak” and “strong.” “Weak” electron emission (current density 10−12–10−7 A/cm2) occurs from polar surfaces of ferroelectric materials in the ferroelectric phase only. A source of the electric field for “weak” FEE excitation is an uncompensated charge, generated by a deviation of macroscopic spontaneous polarization from its equilibrium state under a pyroelectric effect, piezoelectric effect, or polarization switching. The FEE is a tunneling emission current which screens uncompensated polarization charges. It is shown that the FEE is an effective tool for direct domain imaging and studies of electronic properties of ferroelectrics. “Strong” FEE, which is 10–12 orders of magnitude higher than “weak” FEE, achieves 100 A/cm2 and is plasma-assisted electron emission. Two modes of the sur...
TL;DR: In this article, the effects of concentration and distribution of defects controlled by quenching and doping of higher-valent cations on the ferroelectric properties of dense Bi4Ti3O12 ceramics were investigated.
Abstract: The effects of concentration and distribution of defects controlled by quenching and doping of higher-valent cations on the ferroelectric properties of dense Bi4Ti3O12 ceramics were investigated. The remanent polarization (Pr) of non-doped ceramics quenched from 800°C (above the Curie temperature) was twice as large as those of samples subjected to slow cooling to 25°C and quenched from 600°C (below the Curie temperature). These results imply that domain pinning by defects dominates the polarization properties. The incorporation of vanadium and tungsten into Ti site significantly reduced the influence of domain pinning, resulting in a very large 2Pr of over 40 µC/cm2.
TL;DR: The intrinsic coercive field is realized for the first time, in two-dimensional Langmuir-Blodgett polymer films as thin as 1 nm, in good agreement with the theoretical intrinsic value, exhibits the expected dependence on temperature, and does not depend on thickness below 15 nm.
Abstract: The Landau-Ginzburg theory of ferroelectricity predicts the intrinsic coercive field for polarization reversal, but the observed extrinsic coercive field is always much smaller as a result of nucleation, dynamic processes not covered by the static theory. We have realized the intrinsic coercive field for the first time, in two-dimensional Langmuir-Blodgett polymer films as thin as 1 nm. The measured coercive field is in good agreement with the theoretical intrinsic value, exhibits the expected dependence on temperature, and does not depend on thickness below 15 nm.
TL;DR: In this paper, the dependence of P(N), the switched charge per unit area P versus switching event number N, in ABO3 perovskite structure ferroelectric thin films is given.
Abstract: An analytic expression in closed form is given for “fatigue,” the dependence of P(N), the switched charge per unit area P versus switching event number N, in ABO3 perovskite structure ferroelectric thin films is given. The analysis is based upon Arlt’s model for fatigue in bulk perovskites, which involves preferential electromigration of oxygen vacancies to sites parallel to the electrode–ferroelectric interface plane, together with some arguments by Brennan on the effectiveness of such defect planes in pinning domain walls. The model is applied to PZT/Pt with no adjustable parameters and yields in complete agreement with experimental data the dependence of P(N) at different frequencies, different voltages, and different temperatures. Notably, unlike other proposals in the literature, the model does not involve any charge injection from the electrodes.
TL;DR: The design and synthesis of a ferroelectric liquid crystal composed of racemic molecules and shows the thermodynamically stable structure to be a uniformly tilted smectic bow-phase (banana phase), with all layer pairs homochiral and ferroElectric (SmCSPF).
Abstract: We describe the design and synthesis of a ferroelectric liquid crystal composed of racemic molecules. The ferroelectric polarization results from spontaneous polar symmetry breaking in a fluid smectic. The ferroelectric phase is also chiral, resulting in the formation of a mixture of macroscopic domains of either handedness at the isotropic-to-liquid crystal phase transition. This smectic liquid crystal is thus a fluid conglomerate. Detailed investigation of the electrooptic and polarization current behavior within individual domains in liquid crystal cells shows the thermodynamically stable structure to be a uniformly tilted smectic bow-phase (banana phase), with all layer pairs homochiral and ferroelectric (SmC S P F ).
TL;DR: In this article, the authors reported the successful growth of Ba(Ti1−xZrx)O3 (x=0.05-0.2) single-crystal fibers by the laser-heated pedestal growth technique.
Abstract: In this article, we report the successful growth of Ba(Ti1−xZrx)O3 (x=0.05–0.2) single-crystal fibers by the laser-heated pedestal growth technique. A single-phase perovskite structure of the materials has been identified by the x-ray diffraction technique. The phase diagram for Ba(Ti1−xZrx)O3 single crystals is established for x⩽0.2. Dielectric properties as function of temperature and frequency and room-temperature hysteresis loops are measured. The remnant polarization (Pr) and coercive fields (Ec) are obtained and compared for both single crystals and ceramics. The small dielectric relaxation has been observed for the lower-temperature phase transition (around 40 °C at 1 kHz) of the sample with x=0.08. The relaxation times follow the Arrhenius law with τ0=0.4×10−13 s and Erelax=0.53 eV. A common feature of the low-temperature relaxation mode in the sample is also observed, which follows the Arrhenius law with the τ0=0.8×10−10 s and Erelax=0.46 eV.
TL;DR: In this article, the domain structures and phase transitions of relaxor-based piezo-/ferroelectric (1−x)Pb(Mg1/3Nb2/3)O3−xPbTiO3 [PMNT] single crystals, grown from high temperature solutions, have been analyzed by polarized light microscopy using an optical crystallographic approach.
Abstract: The domain structures and phase transitions of relaxor-based piezo-/ferroelectric (1−x)Pb(Mg1/3Nb2/3)O3−xPbTiO3 [PMNT] single crystals, grown from high temperature solutions, have been analyzed by polarized light microscopy using an optical crystallographic approach. The substitution of Ti4+ ions for the B-site complex (Mg1/3Nb2/3)4+ ions in the relaxor PMN results in a long-range symmetry breaking, as revealed by the formation of birefringent macrodomains. The domain structures of the PMNT80/20 crystals indicate a primitive trigonal symmetry at room temperature with a weak birefringence. PMNT crystals with 50% Ti show tetragonal domain structures, reflecting the symmetry of PbTiO3. Single crystals of PMNT65/35 exhibit complex morphotropic domain structures, which are composed of both the trigonal and the tetragonal phase intimately mixed together. The domain structures, the sequence and temperature of phase transitions have been interpreted in relation to the morphotropic phase boundary behavior of the PMN-PT system. It is shown that in situ analysis of domain structures and phase transitions can be used as a nondestructive analytical tool for evaluating the local morphotropic composition and the properties, which sensitively depend upon the individual domains and the Ti4+ concentration. The analysis of morphotropic domain structures and phase transitions provides a better understanding of the microscopic mechanisms of the enhanced piezoelectric properties recently disclosed in PMNT and other relaxor-based piezocrystals.
TL;DR: Far-infrared ellipsometry and low-frequency dielectric measurements in SrTiO3 thin films demonstrate that the Lyddane–Sachs–Teller relation between the optical-phonon eigenfrequencies and the dielectic constant is fully maintained, as is the case in the bulk material.
Abstract: Understanding the behaviour of the dielectric constant in ferroelectric thin films remains a challenging problem. These ferroelectric materials have high static dielectric constants, and so are important for their applications in high-storage-density capacitor structures such as dynamic random access memory (DRAM). But the dielectric constant tends to be significantly reduced in thin films, thereby limiting the potential benefit of ferroelectrics for memory devices. Extensive studies have shown that this phenomenon could be caused by a 'dead layer' of very low dielectric constant between the ferroeletric film and the electrode. And, although very few direct measurements are in fact available, it has been recognized that the lattice dynamical properties in the thin films should also play a key role in the reduction of the dielectric constant. Here we report far-infrared ellipsometry and low-frequency dielectric measurements in SrTiO3 thin films, which demonstrate that the Lyddane-Sachs-Teller relation between the optical-phonon eigenfrequencies and the dielectric constant is fully maintained, as is the case in the bulk material. This indicates that the dramatic reduction of the dielectric constant is a consequence of a profound change of the lattice dynamical properties, in particular of the reduced softening of its lowest optical-phonon mode. Our results therefore provide a better understanding of the fundamental limitations of the dielectric constant values in ferroelectric thin films.
TL;DR: It is believed that specific properties of the domain structure in ferroelectrics with a passive layer can resolve the long-standing "paradox of the coercive field."
Abstract: We study the domain structure in ferroelectric thin films with a "passive" (nonferroelectric) layer at the interface between the film and electrodes. An abrupt transition from a monodomain to a polydomain state has been found with the increase of the passive layer thickness d. The domain width changes very quickly at the transition (exponentially with d(-2)). The slope of the hysteresis loop is in agreement with experiment, assuming realistic parameters of the layer. The slope scales as 1/d, involving only the properties of the layer. We believe that specific properties of the domain structure in ferroelectrics with a passive layer can resolve the long-standing "paradox of the coercive field."
TL;DR: In this paper, the main interest in the area of practical applications of ferroelectrics, particularly at the microwave frequency, is oriented now to room temperature, and in this connection, FerroElectrics like BaxSr1−xTiO3 should be carefully studied.
Abstract: The main interest in the area of practical applications of ferroelectrics, particularly at the microwave frequency, is oriented now to room temperature. In this connection, ferroelectrics like BaxSr1−xTiO3 should be carefully studied. Such materials are characterized by the second order phase transition. In a perfect ferroelectric crystal, the phase transition takes place at temperature TC, which is called the Curie temperature. Real (defected) crystals and ceramic samples are characterized by a presence of built-in electric field and mechanical strains. In the case of the real crystal, the temperature of the phase transition TC′, is displaced to lower temperature and the temperature of the maximum of e(T)Tm is displaced to higher value with respect to TC. Thus, for the real ferroelectric sample (not for an incipient ferroelectric), one has TC′
TL;DR: In this paper, a Maxwell-Wagner series capacitor model is proposed to explain anomalous dielectric properties of ferroelectric superlattices, which can account for most experimental results reported to date.
Abstract: A Maxwell–Wagner series capacitor model is proposed to explain anomalous dielectric properties of ferroelectric superlattices. The results of the model show that a superlattice consisting of normal ferroelectric layers separated by low-resistivity interfacial regions can account for most experimental results reported to date, namely: dielectric enhancement for certain stacking periodicities, giant permittivities, and temperature migration of dielectric maxima as a function of frequency. The predictions of the model are discussed and compared to our own experimental results from thin film superlattice capacitors made by pulsed-laser deposition.
TL;DR: In this paper, the ground-state polarization of PbTiO3 thin films was studied using a microscopic effective Hamiltonian with parameters obtained from first-principles calculations.
Abstract: The ground-state polarization of PbTiO3 thin films is studied using a microscopic effective Hamiltonian with parameters obtained from first-principles calculations. Under short-circuit electrical boundary conditions, (001) films with thickness as low as three unit cells are found to have a perpendicularly polarized ferroelectric ground state with significant enhancement of the polarization at the surface.
TL;DR: In this article, the fundamental physics behind the scarcity of ferromagnetic ferroelectric coexistence was explored and the properties of known magnetically ordered ferro-electric materials were examined.
Abstract: Multiferroic magnetoelectrics are materials that are both ferromagnetic and ferroelectric in the same phase. As a result, they have a spontaneous magnetization that can be switched by an applied magnetic field, a spontaneous polarization that can be switched by an applied electric field, and often some coupling between the two. Very few exist in nature or have been synthesized in the laboratory. In this paper, we explore the fundamental physics behind the scarcity of ferromagnetic ferroelectric coexistence. In addition, we examine the properties of some known magnetically ordered ferroelectric materials. We find that, in general, the transition metal d electrons, which are essential for magnetism, reduce the tendency for off-center ferroelectric distortion. Consequently, an additional electronic or structural driving force must be present for ferromagnetism and ferroelectricity to occur simultaneously.
01 Mar 2000
TL;DR: In this paper, the authors studied the domain structure in ferroelectric thin films with a nonferroelectric layer at the interface between the film and electrodes and found an abrupt transition from a monodomain to a polydomain state with the increase of the passive layer thickness.
Abstract: We study the domain structure in ferroelectric thin films with a "passive" (nonferroelectric) layer at the interface between the film and electrodes. An abrupt transition from a monodomain to a polydomain state has been found with the increase of the passive layer thickness d. The domain width changes very quickly at the transition (exponentially with d(-2)). The slope of the hysteresis loop is in agreement with experiment, assuming realistic parameters of the layer. The slope scales as 1/d, involving only the properties of the layer. We believe that specific properties of the domain structure in ferroelectrics with a passive layer can resolve the long-standing "paradox of the coercive field."
TL;DR: In this paper, the effects of induced biaxial strain on the electrical transport and magnetic properties of epitaxial thin films of SrRuO3 and La0.67Sr0.33MnO3 by structural transitions of ferroelectric BaTiO3 substrates have been studied.
Abstract: Effects of induced biaxial strain on the electrical transport and magnetic properties of epitaxial thin films of SrRuO3 and La0.67Sr0.33MnO3 by structural transitions of ferroelectric BaTiO3 substrates have been studied. Large jumps of electrical resistivity (∼5% in SrRuO3 and ∼12% in La0.67Sr0.33MnO3) and low field magnetization (∼70% in La0.67Sr0.33MnO3) have been observed in the films at the structural transition temperatures of BaTiO3 substrate. The hysteretic jumps are reproducible through many thermal cycles, and they can be attributed to strain effects induced by the substrate. The use of phase transitions of ferroelectric substrates to manipulate lattice strain of epitaxial thin film heterostructures can be a useful way to modify the properties of perovskite oxides.
TL;DR: In this paper, a new concept of polarization reversal and domain dynamics in modified ferroelectrics is presented, where clusters with a reversed polarization within ferroelectric domains are nucleated under applied field in the vicinity of random fields around quenched defects.
Abstract: A new concept of polarization reversal and domain dynamics in modified ferroelectrics is presented. Accordingly, clusters with a reversed polarization within ferroelectric domains are nucleated under applied field in the vicinity of random fields around quenched defects. The random fields significantly lower the activation barrier required for nucleation, thus controlling the kinetics of polarization reversal and domain dynamics. In this model, polarization switching occurs by the breakdown of ferroelectric long-range order, through a polar cluster state.
TL;DR: In this article, the conductivity of mixed-phase composite electrolytes based on poly(ethylene oxide), lithium salts, and ferroelectric materials has been studied and the results showed that the combined addition of rutile type and assured long-term interfacial stability.
Abstract: The electrochemical properties of mixed‐phase composite electrolytes based on poly(ethylene oxide) (PEO), lithium salts , and ferroelectric materials have been studied. The ion‐conduction and lithium‐ion transference numbers of the composite polymer electrolytes were enhanced by the addition of these ferroelectric materials as a ceramic filler. The conductivity behavior of the composite electrolyte depended on the combination of lithium salt and the ferroelectric materials. The conductivity enhancement in the PEO‐LiX composite electrolytes with ferroelectric materials was rationalized by correlating the association tendency of anions with lithium cations and the spontaneous polarization of the ferroelectric ceramics due to their particular crystal structure. The combined addition of rutile type and assured long‐term interfacial stability. All the electrolytes studied here showed decomposition potentials higher than 4V vs. . © 2000 The Electrochemical Society. All rights reserved.
TL;DR: In this article, the fatigue behavior of commercial bulk Lead Zirconate Titanate (PZT) induced by bipolar cycling was investigated, and the authors found that higher cycling fields (2× E c ) yield stronger fatigue, higher AE energy values and lower threshold values for the onset of AE events at high cycle numbers.
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26 Jul 2000
TL;DR: In this paper, the classical Landau model of ferroelectric liquid crystals and its behavior in external electric and magnetic fields were investigated. But the results were limited to the case of Lyotropic liquid crystal and living tissues.
Abstract: Symmetry and ferroelectricity in liquid crystals incommensurate liquid crystals the classical Landau model of ferroelectric liquid crystals ferroelectric liquid crystals in external electric and magnetic fields the generalized Landau model and the behaviour in external fields - dipolar and quadrupolar order in ferroelectric liquid crystals thermodynamic properties of ferroelectric liquid crystals light propagation in ferroelectric liquid crystals the dynamics of ferroelectric liquid crystals local ordering in ferroelectric liquid crystals microscopic theory of ferroelectric liquid crystals classes of ferroelectric liquid crystals, ferroelectricity in mixtures free standing Sm C* films polymeric liquid crystalline ferroelectrics and liquid crystal glasses the possibility of ferroelectric ordering in Lyotropic liquid crystals and living tissues optical bistability and switching in surface stabilized (SS) ferroelectric liquid crystals the soft mode in the Sm A* phase and the electroclinic effect the field distorted helix anti-ferroelectric liquid crystals - structure, theoretical, model, dielectric properties, tristable switching, potential applications ferroelectric liquid crystal devices non-linear optics of liquid crystals.
TL;DR: In this paper, the Rietveld analysis of the powder x-ray diffraction patterns showed that there are two kinds of Bi ions in Bi2O2 layers and one Bi ion in the Bi 2O 2 layers was displaced to the other Bi ion along the polarization direction by about 2% of parameter a, which would contribute to the large 2Pr.
Abstract: Ferroelectric intergrowth Bi4Ti3O12–SrBi4Ti4O15 has been demonstrated to have a large remanent polarization (2Pr) of 30 μC/cm2 and a high Curie temperature of 610 °C using bulk ceramics The Rietveld analysis of the powder x-ray diffraction patterns showed that there are two kinds of Bi ions in Bi2O2 layers One Bi ion in the Bi2O2 layers was displaced to the other Bi ion along the polarization direction by about 2% of parameter a, which would contribute to the large 2Pr