Showing papers on "Ferroelectric ceramics published in 1981"
TL;DR: In this paper, the effects of grain orientation and La-modification on piezoelectric properties in hot-forged ferroelectric ceramics of some bismuth layer structure oxides were studied, comparing them with ordinarily fired (O.F.) ones.
Abstract: The effects of grain orientation and La-modification on piezoelectric properties in hot-forged (H.F.) ferroelectric ceramics of some bismuth layer structure oxides were studied, comparing them with ordinarily fired (O.F.) ones. La-modified and/or grain-oriented (H.F.) ceramics have the larger electromechanical coupling factor than non-modified and/or O.F. ones.
154 citations
TL;DR: In this article, a reported theory originally derived for rhombohedral-phase PLZT 6/65/35 ceramics is shown to be applicable to tetragonal-phase polyhedral-plzT 6.1/35 (PLZT6/65)/35 (P6/35)-ceramics also by introducing the remanent degree of 90° domain alignment γ90.
Abstract: The polarization reversal of some tetragonal-phase PLZT ceramics is studied. The results are explained in terms of 90° domain wall motions. A reported theory originally derived for rhombohedral-phase PLZT 6/65/35 ceramics is shown to be applicable to tetragonal-phase PLZT ceramics also by introducing the remanent degree of 90° domain alignment γ90. As a result, the calculation of coercive force is possible for various PLZT compositions considering the interaction of 90° domain wall motions and reacting forces established by the internal stress state of ferroelectric ceramics. The frequency dependence of coercive force and measurements of switching strain, including depolarization data obtained from either mechanically or electrically produced external forces, confirm the interpretation of predominantly occuring 90° reorientations and are consistent with the extended theory.
59 citations
TL;DR: In this paper, it was shown that knowledge of the sound speeds of a virgin and a poled specimen of a ferroelectric ceramic and certain associated properties of the hysteresis and butterfly loops permits the characterization of its equilibrium material properties in the polar direction consistent with an explicit version of the constitutive relations for the stress and the electric displacement.
Abstract: The mechanical, piezoelectric and dielectric properties of ferroelectric ceramics can be quite complicated. These materials exhibit both instantaneous and transient responses depending on various physical mechanisms such as dipole dynamics and domain switching. Hence the constitutive relations for the stress and the electric displacement which have been formulated are quite complicated and their characterization can be rather intricate. These constitutive relations must also describe the equilibrium responses of the ceramics when the transient processes have come to rest. In the paper, we show that knowledge of the sound speeds of a virgin and a poled specimen of a ferroelectric ceramic and certain associated properties of the hysteresis and butterfly loops permits the characterization of its equilibrium material properties in the polar direction consistent with an explicit version of the constitutive relations for the stress and the electric displacement.
29 citations
TL;DR: In this article, a small ferroelectric ceramic element with an insulating gate transistor and two diodes is used as an electrically addressed, nonvolatile memory device which is read out nondestructively.
Abstract: A small ferroelectric ceramic element is used with an insulating gate transistor and two diodes as an electrically addressed, nonvolatile memory device which is read out nondestructively. The device uses the anomalous photovoltaic effect in ferroelectric ceramics, an effect in which the polarity and magnitude of photovoltages depend on the direction and magnitude of remanent polarization. Experimental results give memory characteristics. The device could be programmed with pulses as short as 200 ns. There is long-time retention of stored data.
20 citations
TL;DR: In this paper, the shape-memory effect in PLZT (Lead Lanthanum Zirconate Titanate) ceramics with composition x/65/35 (4.0 x ǫ 8.0) has been investigated using bending experiments and temperature cycling.
Abstract: The shape-memory effect in PLZT (Lead Lanthanum Zirconate Titanate) ceramics with composition x/65/35 (4.0 x 8.0) has been investigated using bending experiments and temperature cycling. Relationships between load and the degree of bending, together with their temperature dependence, have been determined, and characteristic temperatures associated with the onset and disappearance of the pseudo-plastic shape change are compared with the observed dielectric anomalies. Effects of mechanical stress and electric field on the shape-memory temperatures and the magnitude of strain have also been investigated. It is concluded that domain alignment and the temperature-dependence of spontaneous strain are important factors governing the shape-memory effect in ferroelectrics. Preferred-orientation effects have been confirmed by X-ray diffraction analysis.
15 citations
TL;DR: In this article, acoustic emission induced by poling field was observed in the PZT-like ferroelectric ceramics at the room temperature, and the relationship between AE characteristics and electromechanical coupling coefficients as the measure of poling was established.
Abstract: Acoustic Emission (AE) induced by poling field was observed in the PZT-like ferroelectric ceramics at the room temperature. Relationships between AE characteristics and electromechanical coupling coefficients as the measure of poling show that domains in grains have the various levels of charactersitic threshold field to reverse their polarization directions or to move domain walls. Reversals of domain states with higher threshold field levels occur large amplitude acoustic emissions.
13 citations
TL;DR: In this paper, the electron and hole processes in transparent ferroelectric ceramics (TFC) are considered and the basic concepts about the defects and their relation to the electric conductivity in TPC are analyzed.
Abstract: The electron and hole processes in transparent ferroelectric ceramics (TFC) are considered. The basic concepts about the defects and their relation to the electric conductivity in TPC are analyzed. Results of the studies of electrical properties of the surface and specific features of hologram forming are presented. The basic applications of electron-hole processes in TPC are discussed.
10 citations
TL;DR: The phase transition in PLZT X/65/35 solutions is considered as a diffuse transformation characterized by the two processes comprising it, distortion of the symmetric structure and domain formation as discussed by the authors.
Abstract: The phase transition in PLZT X/65/35 solutions is considered as a diffuse transformation characterized by the two processes comprising it—distortion of the symmetric structure and domain formation. Transparent PSN ceramics are reported to be a promising material in matrix addressing devices due to a low operating voltage and a high P t/P t, ratio.
10 citations
TL;DR: In this article, the authors introduced the activities of ferroelectric ceramics research in China, including the conventional barium titanate and lead zirconate titanate, the induced phase transition in PZT, the (Ba1-XSrx)2NaNb5O15,(Na1XLiX)NbO3 system, the hot forging of Bi4(PbXSr1-Sr 1-X)Ti4O15), the mixed oxide system of the low sintering temperature are discussed briefly.
Abstract: The activities of ferroelectric ceramics research in China are introduced. Besides the conventional barium titanate and lead zirconate titanate ceramics, the induced phase transition in PZT, the (Ba1-XSrx)2NaNb5O15,(Na1-XLiX)NbO3 system, the hot forging of Bi4(PbXSr1-X)Ti4O15, the mixed oxide system of the low sintering temperature are discussed briefly. Research activity on PLZT and its phase transition are presented.
8 citations
TL;DR: In this article, the influence of a low melting second phase added to the grain-oriented ferroelectric ceramics with bismuth layer structure on their densification, forging behavior, grain orientation and electrical properties is investigated by using the hot-forging method combined with liquid phase sintering.
Abstract: The influence of a low melting second phase added to the grain-oriented ferroelectric ceramics with bismuth layer structure on their densification, forging behavior, grain orientation and electrical properties is investigated by using the hot-forging method combined with liquid phase sintering. PbBi2Nb2O9 and Bi4Ti3O12 as host materials; Pb5Ge3O11, PbO and Bi2O3 as liquid phase agents are selected. The presence of liquid phase produces a good effect on hot-forging in PbBi2Nb2O9+Pb5Ge3O11 system. The PbO content ranging from 1 to 3 wt% in PbBi2Nb2O9+PbO system is most effective, and k33 of 15.4% is obtained. On the other hand, liquid phases in Bi4Ti3O12 ceramics have little effect on their densification and forging behavior.
7 citations
TL;DR: In this paper, a fracture mecahnics approach to evaluate a fracture strength of commercially available piezoelectric ceramics is described, where the relationship between nominal fracture toughness kQ and square root of crack tip is represented by two straight lines, and the fracture toughness can be determined by using the specimen with a notch root radius which is smaller than the maximum pore radius in the ceramic.
Abstract: A fracture mecahnics approach to evaluate a fracture strength of commercially available piezoelectric ceramics is described. Relationship between nominal fracture toughness kQ and square root of crack tip is represented by two straight lines, and the fracture toughness KIC can be determined by using the specimen with a notch root radius which is smaller than the maximum pore radius in the ceramic. A new parameter, TIC, which is estimated by the fracture toughness test and SEM observation of the largest pore size, provides a representative fracture strength as a material constant of the ceramics.
TL;DR: In this article, the boundary initial value problem was considered to characterize the transient responses of a partially or thoroughly poled disc of a ferroelectric ceramic and determine its boundary mechanical displacement history.
TL;DR: In this article, a model with internal stresses and a distorted surface layer was proposed, where the thickness of the sample was decreased to the average diameter of the grains, and the measured results were discussed.
Abstract: Thin sections in the thickness range down to 3–5 μm were produced from bariumtitanate ferroelectric ceramics. The small signal dielectric constant, as well as hysteresis loops were measured. Significant deviations from the bulk properties were observed, when the thickness of the sample was decreased to the average diameter of the grains. The measured results are discussed proposing a model with internal stresses and a distorted surface layer.
TL;DR: In this article, it was shown that the photosensitivity of ferroelectric-phase lead lanthanum zirconate titanate (PLZT) ceramics is dramatically improved by ion implantation into the surface exposed to image light.
Abstract: Photographic images can be stored in ferroelectric-phase lead lanthanum zirconate titanate (PLZT) ceramics using a novel photoferroelectric effect. These images are nonvolatile but erasable and can be switched from positive to negative by application of an electric field. We have found that the photosensitivity of ferroelectric PLZT is dramatically improved by ion implantation into the surface exposed to image light. For example, the intrinsic photosensitivity to near-UV light is increased by as much as four orders of magnitude by co-implantation with Ar and Ne. The increased photosensitivity results from implantation-induced decreases in dark conductivity and dielectric constant in the implanted layer. Furthermore, the increased photoferroelectric sensitivity has recently been extended from the near-UV to the visible spectrum by implants of Al and Cr. Ion-implanted PLZT is the most sensitive, nonvolatile, selectively-erasable image storage medium currently known.
TL;DR: In this article, the factors affecting capacitance (dielectric constant) and dielectric loss as a function of AC field have been discussed, and the high field properties of ferroelectric ceramics similar to PZT-4 and PZTs-8 are discussed.
Abstract: The high field properties of ferroelectric ceramics similar to PZT-4 and PZT-8 are of importance due to their major use as transmitting transducer materials. The present work discusses the factors affecting capacitance (dielectric constant) and dielectric loss as a function of AC field.
TL;DR: In this article, a study of photovoltaic response of SBN(50/50) doped with Cu as a function of wavelength of UV-visible radiation was made.
Abstract: A study has been made of photovoltaic response of SBN(50/50) doped with Cu as a function of wavelength of UV-visible radiation. Samples were densified by hot pressing. Spectral behaviour shows the influence of intrinsic transitions and of impurities: there are two maxima of photovoltaic current at 370 and 440 nm, and the maximum at 370 nm does not appear in the spectral response of photovoltage. This shows intrinsic transitions have thus a small influence on the production of high photovoltages. With white radiation provided by a high-pressure mercury-vapor lamp values of 5 V/cm and 4500 V/cm have been obtained for samples non doped and doped with Cu.