Showing papers on "Ferroelectric ceramics published in 1987"
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TL;DR: In this article, a phenomenological model of a vibrating 90°-domain wall in an electric and mechanic stress field is presented, which allows to separate the domain wall and the volume contribution to the complex dielectric, piezoelectric and elastic constants.
Abstract: A phenomenological model of a vibrating 90°-domain wall in an electric and mechanic stress field is presented. The model allows to separate the domain wall and the volume contribution to the complex dielectric, piezoelectric and elastic constants. The results are compared with representative measurements of the above mentioned six material parameters on a Fe-doped PZT sample. It turns out that the absolute values and the temperature dependencies of the intrinsic contributions are comparable to those obtained by a thermodynamical treatment. The ratio S0/P0 (spontaneous deformation/spontaneous polarization) which can also be derived in our model from the measured losses, is in good agreement with other measuring methods. It follows that, although there is as yet no physical interpretation for the loss mechanism, the conception of a vibrating 90°-domain wall under the above described conditions is a useful path towards a better insight into the material properties of ferroelectric ceramics.
127 citations
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TL;DR: In this paper, the role of crystal imperfections in pinning the domain boundaries is discussed, and a modified-PZT ferroelectric ceramic which has rhombohedral symmetry is studied.
Abstract: Transmission electron microscopy and electron diffraction have been used to study ferroelectric domain configurations in a modified-PZT ferroelectric ceramic which has rhombohedral symmetry. Wedge-shaped domains with head-to-tail dipole arrangements and fine lamellar domains are most commonly observed. Switching between these domain types and various other domain configurations is interpreted, and the role of crystal imperfections in pinning the domain boundaries is discussed.
112 citations
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TL;DR: In this article, phase relations and dielectric properties of ceramics in the PZN-BT-PT system are reported, and compositions with the perovskite structure, having high dielectrics constant and low temperature coefficient of capacitance, have been identified.
Abstract: The use of Pb(Zn1/3Nb2/3)O3 ceramics is restricted by the formation of a pyrochlore phase detrimental to both dielectric and piezoelectric properties. Recently it has been shown that a 6 mol% addition of BaTiO3 to PZN suppresses the formation of pyrochlore phase. Phase relations and dielectric properties of ceramics in the PZN-BT-PT system are reported here. Compositions with the perovskite structure, having high dielectric constant and low temperature coefficient of capacitance, have been identified.
110 citations
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Abstract: Domain splitting in the grains of ferroelectric ceramics reduces the internal elastic stresses which are caused by spontaneous deformation. Hysteresis switching reflects the increase or absence of internal stress. Small signal elastic and electric ac fields applied to the ceramic cause reversible domain wall motion thus giving contributions to the dielectric, piezoelectric and elastic constants of these materials.
83 citations
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TL;DR: In this article, a critical grain size for twinning has been found using transmission electron microscopy and the experimentally observed minimum grain size is consistent with values derived from a balance of the cubic to tetragonal elastic strain and twin surface energies.
15 citations
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TL;DR: In this paper, a thermally stimulated current was observed in paraelectric barium-strontium titanate ceramics doped with iron up to 1% in the range above the room temperature.
Abstract: A Thermally Stimulated Current in paraelectric barium-strontium titanate ceramics doped with iron up to 1% was studied in the range above the room temperature. Two TSC peaks, A and B, was observed: The peak A lied around at 90°C, the activation energy being 0.68 eV, whereas the peak B was found around at 130°C with the activation energy of 0.97 eV and regarded as due to migration of oxygen vacancies. These results suggest that the asymmetric hysteresis property in iron-doped ferroelectric ceramics may be brought about from the same charges.
12 citations
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TL;DR: In this paper, a correlation between the calculated electric field gradient seen by Li nuclei and the quadrupole splitting of 7Li NMR line shape allows the authors to localize the Mg or Zn atoms in either the octahedral or tetrahedral sites of the crystalline network.
8 citations
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8 citations
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TL;DR: In this paper, PZT ceramics with a large Zr/Ti ratio and a high Sn content (PSZT) were poled under a variety of single and two-stage conditions designed to deliberately produce non-uniform polarization distributions.
Abstract: Poling conditions are usually established for ferroelectric ceramics in such a way as to produce as high a degree of polarization uniformity as possible. However, ceramics with a very non-uniform polarization distribution in the direction parallel to the polar axis have a number of potential applications including monolithic bimorphs, actuators, and vibrators with unusual modes. In this study, PZT ceramics with a large Zr/Ti ratio and a high Sn content (PSZT) were poled under a variety of single- and two-stage conditions designed to deliberately produce non-uniform polarization distributions. The Laser Intensity Modulation Method (LIMM) was used to determine the distributions in a quantitative and nondestructive manner.
6 citations
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01 Jan 1987
4 citations
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01 Jan 1987
TL;DR: In this paper, the unique electrooptic and photoelectric properties of TFC are used in a number of solid state optoelectronic devices, particularly in high-speed light modulators and shutters, thermal and light filters, electrically controlled colour filters, alphanumeric displays, block data composers, video projectors, and optolectronic voltmeters.
Abstract: Due to their technological and raw material availability as well as resistance to corrosion and irradiation, ceramics are considered optimum materials to solve a number of scientific and technical problems. Studies and applications are progressing rapidly [1,2]. At present, transparent ferroelectric ceramics (TFC) have not yet established for themselves any significant fraction of the market for applications based on capacitance, ferrite, piezo- and constructional ceramics, ceramic substrates etc. However, the unique electrooptic and photoelectric properties of TFC are used in a number of solid state optoelectronic devices, particularly in high-speed light modulators and shutters, thermal and light filters, electrically controlled colour filters, alphanumeric displays, block data composers, video projectors and optoelectronic voltmeters.
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TL;DR: Theoretical equations for remanent polarization and coercive force of ferroelectric ceramics with closed pores are derived as a function of shape factor and volume fraction of closed pores, based on the modified cubes model as mentioned in this paper.
Abstract: Theoretical equations for remanent polarization and coercive force of ferroelectric ceramics with closed pores are derived as a function of shape factor and volume fraction of closed pores, based on the modified cubes model. This theory is applied to the experimental results obtained by Nagata with good agreement between theoretical and experimental ones.
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TL;DR: In this paper, a single-plate actuator capable of bending equivalently to a bimorph was proposed using semiconductive ferroelectric ceramics, which is a simple structure named as a "monomorph" as compared with a multi-stacked type in the bimomorph.
Abstract: A New actuator device is proposed using semiconductive ferroelectric ceramics. This device is a single-plate actuator capable of bending equivalently to a bimorph. A significant difference is simple structure named as a “monomorph” as compared with a multi-stacked type in the bimorph. The bend in the monomorph device is realized by non-uniform electric field distribution in the piezoelectric ceramics, through the semiconductor-metal contact effect (Schottky barrier). The monomorph has been demonstrated in the solid solutions PbZrO3-(K1/2Bi1/2)ZrO3 and BaTiO3-Dy2O3. Both systems reveal the tip deflectionof several hundred micrometers in a 0.5mm thick plate.
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TL;DR: In this paper, the modification par des impuretes des ceramiques piezoelectriques de BaTiO 3 permet d'augmenter leurs temperatures d'emploi jusqu'a 200°C.
Abstract: La modification par des impuretes des ceramiques piezoelectriques de BaTiO 3 permet d'augmenter leurs temperatures d'emploi jusqu'a 200°C
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01 Jan 1987
TL;DR: The properties of piezoelectric ceramics are dependent on crystallites, grain boundaries and pores as well as grain orientation, secondary phase and composite structure.
Abstract: Properties of ferroelectric ceramics are dependent on crystallites, grain boundaries and pores as well as grain-orientation, secondary-phase and composite structure. Such microstructural parameters have large effects on the electric, dielectric, piezoelectric and mechanical properties of piezoelectric ceramics.1,2)
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01 Jan 1987
TL;DR: In this paper, photorefraction (PR) is observed in prepolarized TFC in the absence of applied field throughout the ferroelectric state and in an applied field PR is observed over a wide interval of temperature around a diffuse phase transition.
Abstract: Transparent ferroelectric ceramics (TFC) of the PLZT X/65/35 type (La- doped lead zirconate-titanate, where X is the lanthanum concentration in at.%, 65/35 is the Zr/Ti ratio) display photoconductivity [1], the photovoltaic (PV) effect [2,3] and a pronounced electrooptic effect. For this reason photorefraction (PR) is observed in prepolarized TFC in the absence of applied field throughout the ferroelectric state. In an applied field PR is observed over a wide interval of temperature around a diffuse phase transition, as well as in the ferroelectric state.
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TL;DR: In this paper, the authors present experimental results to show a pronounced manifestation of a new electric-to-mechanical coupling phenomenon in the ferroelectric ceramic PZT 65/35.
Abstract: In this paper, we present experimental results to show a pronounced manifestation of a new electric-to-mechanical coupling phenomenon in the ferroelectric ceramic PZT 65/35. This phenomenon has been previously reported in the electro-optic ceramic PLZT 7/65/35. We believe that it is also present in other ferroelectric materials. In particular, experimental evidence indicates that this coupling phenomenon during the process of poling results in flexural mechanical displacements which are much larger than the combined changes in thickness due to domain switching and conventional piezoelectric coupling. Its influence also increases markedly with remanent polarization.
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TL;DR: In this article, the authors studied the domain structure realignment in PLZT ferroelectric ceramics in a broad temperature range and showed that the intensity of domain processes depends on the mode of sample polarization.
Abstract: Processes of the domain structure (DS) realignment in PLZT ferroelectric ceramics are studied in a broad temperature range. It is established that in samples of polarized ceramics changes of temperature are accompanied by the DS realignment in the absence of the electric field. The intensity of domain processes depends on the mode of sample polarization.
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01 Jan 1987
TL;DR: In this article, the authors have analyzed the different requirements of production and given recommendations to follow in the search for new compositions of transparent ceramics and showed that the strong defect structure of PLZT (vacancies in sublattices A and B of the perovskite structure at concentrations of 1021cm-3, oxygen vacancies, possible implantation of La ions in sub-lattice B) suggest the existence of local dipoles at temperatures much higher (by 100 degrees and more) than the temperature T c of the maximum value of dielect
Abstract: The study of the interrelation between composition, structure and physical and chemical properties of a material with respect to possible control of its characteristics is one of the most important problems of physics and chemistry of the solid state. And this is completely the case with the TFC: we have analyzed in Part I the different requirements of production and given recommendations to follow in the search for new compositions. Up to the present time the lanthanum doped lead zirconate-titanate (PLZT) system has been most studied for science and applications [1]. As a rule, transparent ceramics are produced from chemically coprecipitated raw material by two-stage hot pressing techniques (in vacuo with a following treatment in oxygen or air) - see, e.g., [2]. There are, of course, a lot of different technological variations. The strong defect structure of PLZT (vacancies in sublattices A and B of the perovskite structure at concentrations of 1021cm-3, oxygen vacancies, possible implantation of La ions in sublattice B) suggest the existence of local dipoles at temperatures much higher (by 100 degrees and more) than the temperature T c of the maximum value of dielectric constant, and make the phase transition in ceramics strongly diffused [3,4]. Consequently, the PLZT ceramics along with the “classical” compound of lead magnesium-niobate (PMN) are becoming a model for studies of diffusion of the phase transition.