Showing papers by "L. E. Cross published in 1990"
TL;DR: In this paper, a classification of complex lead perovskites is presented based on the relative scale of long-range cation order, and the implications of Cation order in relation to relaxor and normal ferroelectric behavior are discussed.
Abstract: From a number of studies on ferroelectric and related materials based on complex lead perovskites [Pb(Bx′B1−x″)O3], it is apparent that the B-site cation order influences the crystallography, phase transitions, and other physical properties. A classification of complex lead perovskites is presented based on the relative scale of long-range cation order. In particular, we discuss the implications of cation order in relation to relaxor and normal ferroelectric behavior.
317 citations
TL;DR: In this paper, the K2Ln3+Nb5O15 system has been investigated for a range of rare-earth ions (La3+ to Ho3+, Y3+), and the temperature-dependent dielectric properties indicate that all but the La3+-containing materials have tungsten bronze orthorhombic structure.
80 citations
TL;DR: In this paper, the pyroelectric properties of morphotropic phase-boundary lead-barium-niobate tungsten-bronze ferroelectric single crystals have been investigated.
Abstract: Low‐temperature (10–300 K) dielectric and pyroelectric properties of morphotropic‐phase‐boundary lead‐barium‐niobate tungsten‐bronze ferroelectric single crystals have been investigated. Strong ‘‘Debye‐like’’ dielectric dispersion, along a nonpolar direction (perpendicular to the polarization direction), has been observed and characterized by dielectric spectrum techniques. A direct charge measurement method has been used to study the low‐temperature pyroelectric properties in polar and nonpolar directions. A ‘‘frozen‐in’’ polarization component in a nonpolar direction is also reported. The low‐temperature relaxation effects are explained by the internal reorientation polarization perturbation and a thermally agitated local dipole fluctuation model.
56 citations
TL;DR: In this paper, the polarization mechanisms of the morphotropic phase boundary compositions of tungsten bronze relaxor ferroelectrics, Pb1−xBaxNb2O6 (PBN[( 1−x) %]), were investigated by means of electrical, thermal, optical, and electron microscopic methods.
Abstract: Investigations of the polarization mechanisms in tungsten bronze relaxor ferroelectrics, Pb1–xBaxNb2O6 (PBN[(1−x) %]), in particular, of the morphotropic phase boundary compositions have been carried out for both ceramics and bulk crystals by means of electrical, thermal, optical, and electron‐microscopic methods. Relations of phase‐transition behavior with compositional and polarizational fluctuations have been carefully studied. Instead of a sharp boundary composition, it is found that a rather wide composition range, 1−x≊0.63±0.03 in Pb1−xBaxNb2O6, corresponds to the orthorhombic and tetragonal morphotropic phase boundary. It is demonstrated with the help of optical conoscopic interference figures that for the near‐morphotropic phase boundary single crystal PBN of tetragonal symmetry, the polarization vector can be switched orthogonally to an orthorhombic phase simply by the application of an electric field, which authenticates optically the 90° polarization rotation. A transmission electron microscope study in the temperature range from −180 °C to room temperature revealed the presence of incommensurate ferroelastic domains in the morphotropic phase boundary composition PBN crystals. In light of the above observed experimental data, the polarization mechanisms of the morphotropic phase‐boundary compositions are discussed in terms of qualitative thermodynamics.
51 citations
TL;DR: In this paper, the inhomogeneous distributions of internal shear stress and electrical field induced by external shear or applied electric field around a Griffith's type III crack tip in ferroelectric ceramics have been analyzed.
33 citations
01 Jan 1990
TL;DR: In this paper, a simple classification scheme was presented which essentially relates the scale of B-site cation order in complex lead based perovskites Pb(B′B″)O3 with either normal ferroelectric (antiferroelectric) or relaxor Ferroelectric behavior, as observed in these materials.
Abstract: A simple classification scheme is presented which essentially relates the scale of B-site cation order in complex lead based perovskites Pb(B′B″)O3 with either normal ferroelectric (antiferroelectric) or relaxor ferroelectric behavior, as observed in these materials.
20 citations
TL;DR: In this article, a simple classification scheme was presented which essentially relates the scale of B-site cation order in complex lead based perovskites Pb(B′B″)O3 with either normal ferroelectric (antiferroelectric) or relaxor Ferroelectric behavior, as observed in these materials.
Abstract: A simple classification scheme is presented which essentially relates the scale of B-site cation order in complex lead based perovskites Pb(B′B″)O3 with either normal ferroelectric (antiferroelectric) or relaxor ferroelectric behavior, as observed in these materials.
20 citations
TL;DR: In this article, the SHG signal between 25 and 250°C was measured for a flux-grown single crystal, high-purity single-crystal fibers, and powder (0.5 μm average particle size).
17 citations
TL;DR: In this article, a laser interferometer was used to study the phase delay of converse piezoelectric response, and the real and imaginary parts of the piezolectric coefficients were calculated from the measured strain amplitude and the phase delays of the strain with respect to the applied electric field for PZT-5 ceramics.
Abstract: A laser interferometer was used to study the phase delay of converse piezoelectric response. The real and imaginary parts of the piezoelectric coefficients were calculated from the measured strain amplitude and the phase delay of the strain with respect to the applied electric field for PZT-5 ceramics. The same coefficients were also calculated from measured resonance properties by using Smits's iterative method. The results were in good agreement. The phase delay of the strain with respect to the applied electric field was also studied near resonance frequencies; the result was in excellent agreement with the classic vibration theory.
14 citations
TL;DR: In this article, the structural and dielectric properties of compositions from the solid solution system (1−x) Pb(Sc 1/2Ta1/2)O3-(x)PbTiO3 are characterized.
Abstract: The preliminary characterization of the structural and dielectric properties of compositions from the solid solution system (1−x) Pb(Sc1/2Ta1/2)O3-(x) PbTiO3 is presented. A morphotropic phase boun...
13 citations
TL;DR: In this article, the authors reported preliminary results on the fabrication of perovskite PZT and PLZT thin films using a sputtering technique and showed that growth at temperatures below 550 ° C yielded a major pyrochlore structure phase.
Abstract: This paper reports preliminary results on the fabrication of perovskite PZT and PLZT thin films using a sputtering technique. For glass, quartz and sapphire substrates, it was necessary to raise the substrate temperature above 550 ° C to achieve perovskite tetragonal structures of interest. Growth at temperatures below 550 ° C yielded a major pyrochlore structure phase. Excess of PbO in the target was also required to maintain stoichiometry in these films.
TL;DR: In this paper, the dielectric and piezoelectric phase angles of the relaxor ferroelectric ceramic (1−x) Pb(Mg1/3Nb2/3)O3-xPbTiO3(x =.07) with 1% La (lanthanum) were measured as a function of bias field using a bar resonator.
Abstract: Complex material parameters (piezoelectric coefficient d31, elastic s11 E, and the dielectric constant K33) of the relaxor ferroelectric ceramic (1−x) Pb(Mg1/3Nb2/3)O3-xPbTiO3(x =.07) with 1% La (lanthanum) were measured as a function of bias field using a bar resonator. The values of the dielectric and piezoelectric phase angles are found to be comparable (i.e., around 0.04 for a d.c. bias field of 2.5 kV/cm), while the elastic phase angle is an order of magnitude smaller (0.001 for the same d.c. bias). For comparison of complex material parameters found from bar resonators, a sample in the form of a small disk is used to measure Poisson's ratio as well as the real components of the piezoelectric and elastic coefficients as a function of bias field.
TL;DR: In this paper, a morphotropic phase boundary exists and separates two ferroelectric phases (tetragonal 4mm and orthorhombic m2m) at a temperature higher than Tc At T 063.
Abstract: Lead barium niobate (Pb1−xBaxNb2O6, PBN) is one of the oxide octahedron-type ferroelectrics with a tungsten bronze-type structure1,2,3 The crystal has a prototype symmetry of tetragonal 4/mmm at a temperature higher than Tc At T 063) with a polarization vector along the [110] direction (referring to the prototype symmetry)4,5 For a composition in the vicinity of 1−x-063, a morphotropic phase boundary exists and separates two ferroelectric phases (tetragonal 4mm and orthorhombic m2m) It is reported when a composition is close to the MPB, many useful physical properties would be enhanced (eg, dielectric constant6,7, piezoelectric coefficient7, and pyroelectric coefficient8) and are essentially temperature independent It is thus of theoretical and practical significance to study MPB PBN compositions
TL;DR: In this paper, a lead magnesium niobate (PMN) thin film was prepared by a solution sol-gel (SSG) technique and X-ray diffraction analysis indicated the perovskite phase of PMN formed at a temperature as low as 775°C.
Abstract: Lead magnesium niobate (PMN) thin films were prepared by a solution sol-gel (SSG) technique. X-ray diffraction analysis indicated that the perovskite phase of PMN formed at a temperature as low as 775°C. A highly oriented film along (111) direction was obtained on silicon substrate. The orientation and crystallization rate were strongly influenced by the type of substrate and heating conditions.
TL;DR: In this paper, the reflectance coefficient of SbSI has been studied under a small temperature modulation using null ellipsometry to determine the temperature sensitivity of the optical constants, and it was found that the reflective coefficient was highly sensitive to small temperature changes at wavelengths around the absorption edge.
Abstract: The reflectance coefficient of SbSI has been studied under a small temperature modulation using null ellipsometry. The intent of this work was to determine the temperature sensitivity of the optical constants. The reflectance coefficient was found to be highly sensitive to small temperature changes at wavelengths around the absorption edge. It is feasible to detect temperature changes of OC by monitoring the reflectance coefficient.
TL;DR: In this paper, the structural features of important families of oxide ferroelectrics and superconductors are reviewed to establish the crystal chemical similarities and some of the parameters contributing to the structural stability and influencing the respective transition temperatures are considered.
Abstract: The structural features of important families of oxide ferroelectrics and superconductors are reviewed to establish the crystal chemical similarities. Some of the parameters contributing to the structural stability and influencing the respective transition temperatures are considered. The location of most of the known ferroelectrics and superconductors are depicted in two ternary composition diagrams.
TL;DR: There has been considerable discussion of crystalline ferroelectrics with a glassy polarization phase, and there are materials in which evidences for regions of local, randomly oriented polarization far above the transition temperature Tc, up to a temperature Td, have been found.
Abstract: There has been considerable discussion of crystalline ferroelectrics with a glassy polarization phase. There are materials in which evidences for regions of local, randomly oriented polarization far above the transition temperature Tc, up to a temperature Td, have been found1.
TL;DR: In this paper, the authors investigated the dispersion of bulk modes as well as interface modes in the 180 degrees periodic domain structure and derived the expressions for the Hamiltonian and explicit equations for dispersion.
Abstract: Electroacoustic waves are investigated in the 180 degrees periodic domain structure. Some elementary methods are provided. The expressions for the Hamiltonian and the explicit equations for the dispersion of bulk modes as well as interface modes are obtained. The results are analysed and a possible elementary mode is proposed.
06 Jun 1990
TL;DR: In this paper, electrical properties of hot-pressed PLZT 9.5/65/35 ceramics were investigated as a function of applied voltage, temperature, and humidity, and it was determined that surface conductivity shows a greater increase with humidity than the bulk conductivity.
Abstract: Electrical properties of hot-pressed PLZT 9.5/65/35 ceramics were investigated as a function of applied voltage, temperature, and humidity. Conductivity at moderate field levels follows the Arrhenius equation with an activation energy of 1.24 eV. For the values of the electric field in the range of 15 to 80 kV/cm and temperature extending up to 150 degrees C, electrical conductivity fits the behavior predicted by the Schottky model. Using a guarded electrode arrangement, it was determined that surface conductivity shows a greater increase with humidity than the bulk conductivity. Surface conductivity in a humid environment increases with the time of exposure and can be up to two orders of magnitude higher than conductivity in dry air. >
TL;DR: In this article, the pyroelectric properties of a triglycerol-gelatin film were examined by using the Byer-Roundy and dynamic Chynoweth technique in the temperature range from −100°C to +60°C.
Abstract: Several members of a new family of synthetic polypeptide polymers in form of gelatin thick films (20-80 μm thick) were studied for possible sensor applications. In the present paper the properties of a triglycerol-gelatin film are reported. The pyroelectric properties of the film were examined by using the Byer-Roundy and dynamic Chynoweth technique in the temperature range from −100°C to +60°C. The pyroelectric current measured by the Byer-Roundy method is heavily dominated by the thermally stimulated currents. However, the dynamic technique of Chynoweth revealed a true reversible pyroelectric response of the film. The value of the observed pyroelectric coefficient was found to be comparable to that of PVDF, the best known pyroelectric and piezoelectric polymer material.
16 Jul 1990
TL;DR: In this article, a morphotropic phase boundary has been shown to exist in the composition region near 1-x = 0.63l and optical memory effects associated with a field-induced phase transition were also observed for the nearMPB composition single crystals.
Abstract: The lead barium niobate solid solution system, Pbl-xBaxNb206 (PBN[( l-x)%l), has drawn increasing interest mainly because of its unique properties as a tungsten bronze type ferroelectric relaxor with a morphotropic phase boundary (MPB) separating a tetragonal ferroelectric phase 4mm (with polarization dipole along [OO 11) and an orthorhombic ferroelectric phase m2m (with polarization dipole along [ 1 lo]). Extraordinarily large dielectric, piezoelectric, and pyroelectric properties of morphotropic phase boundary PBN compositions have been reported. A morphotropic phase boundary has been shown to exist in the composition region near 1-x = 0.63l. Optical memory effects associated with a field-induced phase transition were also observed for the nearMPB composition single crystals172. In the present paper we report measurements of linear electrooptic coefficients and the temperature variation of the optical birefringence. Analysis of the above results were made in association with previously measured dielectric and pyroelectric properties. Electrooptic response of the PBN crystals to applied square wave voltage pulses were also studied. Transparent optical quality single crystals of Pb1-~BaxNb206 , where 1-x varies from 0.50 to 0.65, were grown by Czochralski technique. Transverse linear electrooptic coefficients were measured by using both a standard half wave voltage method and a Senarmont compensator method employing lock-in phase detection techniques. Measurements of temperature variation of optical birefringence, An(T), were carried out by monitoring the transmitted intensity between crossed polarizers in the temperature range from room temperature up to -450OC depending on the ferroelectric phase transition temperature of the corresponding sample.
06 Jun 1990
TL;DR: In this paper, the responses of piezoelectric and dielectric coefficients of lead zirconate-titanate (PZT) ceramics to AC electric fields have been directly investigated.
Abstract: By using an optical interferometer and other more conventional methods, the responses of piezoelectric and dielectric coefficients of lead zirconate-titanate (PZT) ceramics to AC electric fields have been directly investigated. The experimental results demonstrate the importance of electromechanical nonlinearities present in the ferroelectric ceramics. A phenomenological theory, based on a model of G Arlt et al. (1987), has been extended to describe the extrinsic contribution to piezoelectric, elastic, and dielectric coefficients. This can be attributed to both the linear and nonlinear vibrations of 90 degrees domain walls in tetragonally distorted ferroelectric ceramics. The proposed theory shows qualitative agreement with the experimental results. >
06 Jun 1990
TL;DR: In this article, the 0.9PMN-0.1PT ferroelectric relaxor composition was studied as a function of the electric bias field at 500 Hz using a laser interferometer.
Abstract: The hydrostatic piezoelectric coefficient d/sub h/, in the 0.9PMN-0.1PT ferroelectric relaxor composition was studied as a function of the electric bias field at 500 Hz using a laser interferometer. It was found that d/sub h/ approaches a very large value of approximately 300 pC/N and then saturates at an electric bias field of approximately 3.5 kV/cm. The voltage coefficient and the sensitivity were also found to be comparable to and larger than, respectively, those in lead zirconate-titanate (PZT) ceramics despite a high dielectric constant in the relaxor material. Unlike the d/sub 33/ and d/sub 31/ piezoelectric coefficients, d/sub h/ did not, under the experimental conditions, depend on electric bias field in a manner predicted by the phenomenological theory. >
TL;DR: In this paper, the pyroelectric response of a triglycerol-gelatin film, belonging to a new family of pyro-electric modified polypeptides, was examined over a temperature range from-20°C to +85°C, by the dynamic Chynoweth1 technique.
Abstract: The pyroelectric response of a triglycerol-gelatin film, belonging to a new family of pyroelectric modified polypeptides, is examined over a temperature range from-20°C to +85°C, by the dynamic Chynoweth1 technique. The size of the observed pyroelectric coefficient of the film is found to be comparable to that of polyvinylidene fluoride (PVDF), the best known piezoelectric and pyroelectric polymer.
06 Jun 1990
TL;DR: In this paper, the piezoelectric, electromechanical, and dielectric properties of lead lanthanum zirconate titanate (PLZT) ceramics at different remanent polarization levels were studied for acoustic imaging applications.
Abstract: The piezoelectric, electromechanical, and dielectric properties of lead lanthanum zirconate titanate (PLZT) ceramics at different remanent polarization levels were studied for acoustic imaging applications The remanent polarizations at different levels were achieved by applying electric switching pulses with different widths The piezoelectric coefficient obtained by direct and converse effects decreased with the remanent polarization, but the relations were not linear The electromechanical coupling factor also decreased with the remanent polarization and the mechanical quality factor was not basically affected by remanent polarization The dielectric properties varied in different polarization states, but they had different behaviors for different crystal structures of samples The aging effect was researched in several partially polarized states and in the completely polarized state No apparent difference in aging rates was observed >
06 Jun 1990
TL;DR: In this article, the use of yttrium barium copper oxide films (the orthorhombic superconducting phase commonly referred to as one-two-three, termed as YBCO) as electrodes on ferroic materials for use in dielectric and piezoelectric devices was investigated.
Abstract: The goal of the study reported was to qualify the use of yttrium barium copper oxide films (the orthorhombic superconducting phase commonly referred to as one-two-three, termed as YBCO) as electrodes on ferroic materials for use in dielectric and piezoelectric devices. The substrates used were barium titanate (BT), lead zirconate titanate (PZT), and lead magnesium niobate-lead titanate (92.5PMN-7.5PT). The YBCO films were synthesized on the substrates by spin coating, spraying, screen-printing, and tape cast laminations. The dielectric loss data as a function of temperature and frequency of YBCO electrode samples indicate differing degrees of interfacial interaction. The coatings did not have a good adhesion on PMN-7.5PT. The interaction with BT was excessive. The PZT-YBCO system appears to be the most compatible with minimum adverse interactions and excellent adhesion properties without substantial loss of electrical properties. >
06 Jun 1990
TL;DR: In this paper, the dielectric and pyroelectric properties of gelatin-based synthetic polypeptides were studied for possible sensor applications, and gelatin films modified with triglycerol were found to have particularly interesting properties.
Abstract: The dielectric and pyroelectric properties of gelatin-based synthetic polypeptides were studied for possible sensor applications. Among the compositions examined, gelatin films modified with triglycerol were found to have particularly interesting properties. The films exhibited a strong dispersion in the dielectric permittivity accompanied by a high dielectric loss near room temperature. The possible relaxational mechanisms responsible for the observed dielectric behavior are discussed. The pyroelectric properties of the films were investigated. The measurements performed on prepoled samples proved the presence of a true, reversible pyroelectric response in the films. The value of the pyroelectric coefficient of the films was found to be comparable to that of PVDF polymer. >