Showing papers by "L. E. Cross published in 1991"
TL;DR: In this paper, a phenomenological theory of Arlt, Dederichs, and Herbiet has been extended to include the nonlinear contributions of lead zirconate titanate Pb(ZrxTi1−x)O3 ceramics.
Abstract: The nonlinear electric and electromechanical responses of lead zirconate titanate Pb(ZrxTi1−x)O3 ceramics to an external ac electric field have been measured under different driving levels. The onset of measurable nonlinearity is observed to be accompanied by the appearance of hysteresis loops. This lossy nature suggests that the nonlinearities in a ferroelectric ceramic are generated by the domain‐wall motion. In addition, aging experiments and the bias field dependence of the threshold field (onset of nonlinearity) all indicate the extrinsic nature of the nonlinear behavior of ferroelectric ceramics. A phenomenological theory of Arlt, Dederichs, and Herbiet [Ferroelectrics 74, 34 (1987)] has been extended to include the nonlinear contributions. With only 90° wall vibration being considered, the theory leads to some basic understanding of the experimental results.
336 citations
TL;DR: In this article, the relaxor ferroelectric bears strong resemblance to spin and dipolar glasses, and the dielectric dispersion will have a characteristic freezing temperature, near which the relaxation time distribution strongly broadens extending into the macroscopic time regime.
Abstract: Evidence has been found that the relaxor ferroelectric bears strong resemblance to spin and dipolar glasses. The dielectric dispersion will be shown to have a characteristic freezing temperature, near which the relaxation time distribution strongly broadens extending into the macroscopic time regime. Below this characteristic temperature, a remanent polarization can be sustained. It is proposed that the glassy behavior arises due to correlations between phase separated superparaelectric moments.
329 citations
TL;DR: Construction d'un modele tridimensionnel de Ginzburg-Landau pour decrire les structures maclees tetragonales resultant d'une transition de phase ferroelectrique propre O λ -C 4ν du premier ordre dans les perovskites.
Abstract: A three-dimensional Landau-Ginzburg model has been constructed to describe the tetragonal twin structures resulting from a first-order ${\mathit{O}}_{\mathit{h}\mathrm{\ensuremath{-}}}$${\mathit{C}}_{4\mathit{v}}$ proper ferroelectric phase transition in perovskites. The model takes into account the nonlinear and nonlocal characteristics of the polarization (order parameter) as well as the electromechanical coupling. Quasi-one-dimensional (Q1D) analytic solutions for the space profiles of the order parameter are obtained for a 180\ifmmode^\circ\else\textdegree\fi{} twin and for a charge-neutral 90\ifmmode^\circ\else\textdegree\fi{} twin with a special choice of parameters. Without the presence of interfacial defects, such as dislocations, the Q1D solutions require the support of inhomogeneous mechanical constraints. Elastic deformation and dimensional changes associated with the twin structures, and their implications on the piezoelectric effect in ferroelectric ceramics, are also addressed.
288 citations
TL;DR: In this paper, transmission electron microscopy (TEM) has been used to explore details of the structural phase transitions and corresponding microstructural features in the solid solution of Pb1−xBaxNb2O6 (PBN) tungsten bronze ferroelectrics at compositions embracing the morphotropic phase boundary between orthorhombic and tetragonal ferroelectric phases.
Abstract: Transmission electron microscopy (TEM) has been used to explore details of the structural phase transitions and corresponding microstructural features in the solid solution of Pb1−xBaxNb2O6 (PBN) tungsten bronze ferroelectrics at compositions embracing the morphotropic phase boundary between orthorhombic and tetragonal ferroelectric phases. In addition to the ferroelectric domain structures that were consistent with the expected symmetries, incommensurate ferroelastic phases were observed. The “onset” and “lock-in” transition temperatures are a function of the Pb/Ba ratio, and for lead-rich compositions it appears that the incommensurate distortion may occur above the ferroelectric Curie temperature in the paraelectric phase.
46 citations
TL;DR: In this paper, the porosity of ferroelectric tungsten bronze Pb0.6Ba0.4Nb2O6 (PBN:60) with and without La3+-modification has been investigated.
38 citations
TL;DR: The pyroelectric response of selected compositions from this solid solution system have been investigated in this article, and the results indicate the presence of a relatively broad, curved morphotropic phase boundary.
Abstract: The pyroelectric response of selected compositions from this solid solution system have been investigated. The nature of the temperature dependence of the pyroelectric coefficient for the compositions examined indicate the presence of a relatively broad, curved morphotropic phase boundary, [x = 0.3–0.45]. The high values of pyroelectric coefficient achievable, in particular for low x compositions [x = 0–0.1], suggest potential application of these materials as highly efficient and versatile field-stabilized devices.
24 citations
TL;DR: In this paper, thin films of lead zirconate titanate have been fabricated for application to a new family of flexure-wave piezoelectric micromotors that are characterized by low speed and high torque.
Abstract: Thin films of lead zirconate titanate have been fabricated for application to a new family of flexure-wave piezoelectric micromotors that are characterized by low speed and high torque. The high relative dielectric constant and breakdown strength of the films lead to high stored energy densities. Evaluation of the film as a bimorph yielded a value of -88 pC/N for the transverse piezoelectric strain coefficient, d31; the relevant electromechanical coupling factor, k31, calculated thereupon was 0.22. The development of the piezoelectric ultrasonic micromotors from the PZT thin films, and the architecture of the stator structure are described. Nonoptimized prototype micromotors show rotational velocities of 100–300 rpm at drives of 3–5 V.
16 citations
TL;DR: In this article, the authors collected and reviewed supporting evidence with particular emphasis on the nature of these precursor phase transitions in the temperature range 93-250°K, and reported the real part of the intrinsic dielectric constant at microwave frequencies is in excess of 120, with a loss tangent δ≤0.2.
Abstract: Since our first two publications1,2 pointing out the possible close interrelationship between high temperature superconductivity and an incipient or relaxor-like ferroelectricity, there have been numerous additional reports which support such an interrelationship. It is the purpose of this paper to collect and review this supporting evidence with particular emphasis on the nature of these precursor phase transitions in the temperature range 93-250°K. New dielectric measurements at 9.2 GHz are also reported on YBa2Cu3O7-x showing the real part of the intrinsic dielectric constant at microwave frequencies is in excess of 120, with a loss tangent δ≤0.2.
9 citations
TL;DR: It is feasible to detect temperature changes of 10(-2) degrees C by monitoring the reflectance, and thus MoS(2) is a potential candidate material for the pyrooptical sensors.
Abstract: The temperature sensitivity of the reflectance of MoS2 under small temperature modulations has been investigated. It is feasible to detect temperature changes of 10−2°C by monitoring the reflectance, and thus MoS2 is a potential candidate material for the pyrooptical sensors.
7 citations
TL;DR: The dielectric and pyroelectric properties of triglycerol-gelatin thick films were studied as a function of temperature and frequency and the value of the pyro electric coefficient of the films was found to be comparable to that of polyvinylidene fluoride (PVDF).
Abstract: The dielectric and pyroelectric properties of triglycerol-gelatin thick films were studied as a function of temperature and frequency. The films exhibited a strong dispersion in the dielectric permittivity accompanied by a high dielectric loss near room temperature. The pyroelectric current measured by the static Byer-Roundy method is heavily dominated by the thermally stimulated currents. Measurements performed on prepoled samples using the dynamic technique of A.G. Chynoweth (1956) clearly proved the presence of a true, reversible pyroelectric response in the examined films. The value of the pyroelectric coefficient of the films was found to be comparable to that of polyvinylidene fluoride (PVDF). >
7 citations
TL;DR: Taylor et al. as discussed by the authors used relaxor ferroelectric ceramics and laser interferometer to construct a relaxor relaxor for fiberglass fiber-optic fiberglass.
Abstract: Keywords: relaxor ferroelectric ceramics ; laser interferometer Note: Taylor, Dj Penn State Univ,Mat Res Lab,University Pk,Pa 16802Fq936Times Cited:0Cited References Count:12 Reference LC-ARTICLE-1991-009doi:10.1007/BF00723374 Record created on 2006-08-21, modified on 2017-05-10
TL;DR: In this article, the displacements of opposing surfaces of PZT ceramic bar resonators were measured under length extensional mode resonance using a high frequency double beam laser interferometer system.
Abstract: The displacements of opposing surfaces of PZT ceramic bar resonators were measured under length extensional mode resonance using a high frequency double beam laser interferometer system. The results of the measured displacements are in good agreement with displacement values calculated using modified Cady equations.
TL;DR: Y1Ba2Cu3O7-x (YBCO) was studied as a potential electrode material for devices utilizing perovskite ferroelectric materials as discussed by the authors, and the YBCO electrode was found to react more with the PMN based substrates.
Abstract: Y1Ba2Cu3O7-x (YBCO) was studied as a potential electrode material for devices utilizing perovskite ferroelectric materials. Electrode thick film coatings were made on Barium Titanate (BT), Lead Magnesium Niobate-Lead Zinc Niobate (PMN-24 PZN), Lead Magnesium Niobate-Lead Titanate (PMN-7.5PT) and Lead Zirconate Titanate (PZT). Conventional slow fire techniques with flowing oxygen were initially used to fire the electrode onto the substrate. These 24 hour firing cycles caused excessive interactions at the electrode-substrate interface, as determined by dielectric constant and loss data. PbO vapor pressure was found to play a key role in the adhesion of these coatings.An alternate “fast fire” technique was excellent in producing conductive, adhering electrode coatings. YBCO electroded PZT samples performed identical to PZT electroded with gold. The YBCO electrode was found to react more with the PMN based substrates.
TL;DR: In this paper, thin films of PbZrO 3 -Pb(Zn 0.33 Nb 0.67 )0 3, with PZN contents of 8-12%, were fabricated through the sol-gel spin-on technique.
Abstract: Thin films of PbZrO 3 -Pb(Zn 0.33 Nb 0.67 )0 3 , with PZN contents of 8- 12%, were fabricated through the sol-gel spin-on technique. The structural, low frequency capacitive, and polarization reversal characteristics were investigated as a function of composition in this solid solution system. The switching of ferroelectric polarization was tested by a sequence of square wave pulses consisting of two positive pulses followed by two negative pulses. Compositions with higher PZN contents are promising for switching applications; the films were typically characterized by a switched charge of 4-14 μC/cm 2 , coercive field of around 30 kV/cm, and relative permittivity of 400-800.
TL;DR: In this article, the authors show that the piezoelectric effect in ferroelectric ceramics cannot be explained by the average of the intrinsic piezo-electric effect of the oriented ferro-electric domains.
Abstract: Experimental evidence show that the piezoelectric effect in ferroelectric ceramics cannot be accounted for by the average of the intrinsic piezoelectric effect of the oriented ferroelectric domains. The measured values of piezoelectric moduli dij are usually 60-70% larger than the calculated average values at room temperature.1,2,3 The difference as well as the absolute values of dij become smaller when the system is cooled,4 which suggests that reversible ferroelectric/ferroelastic domain wall movement may be the cause for the discrepancy, because the walls are more mobile at higher temperatures.
TL;DR: In this paper, the temperature dependence of pyroelectric coefficients of lead barium niobate Pb1−xBaxNb2O6 (PBN) single crystals using the Byer-Roundy technique was investigated.
Abstract: The temperature dependence of the pyroelectric coefficients of lead barium niobate Pb1−xBaxNb2O6 (PBN) single crystals were investigated using the Byer-Roundy technique. Pyroelectric coefficients were found to be enhanced in single crystals of the near-morphotropic phase boundary (MPB) compositions. High pyroelectric coefficients (336 μC/m2−K, 1 − × = 0.684) and switchable polarization vectors between the two perpendicular crystallographic directions ([001] and [110]) in crystal of near-morphotropic phase boundary composition (1 − x = 0.615) were found to be of interest for pyroelectric device applications.