Showing papers on "Ferroelectric ceramics published in 1978"
TL;DR: In this article, the phase diagrams of four ferroelectric ceramics based on lead zirconate (PbZrO 3 ) were determined using dielectric constant and loss measurements.
83 citations
TL;DR: In this article, the physical nature of dielectric losses is explained by the damping of moving 90° domain walls for frequencies up to 108 Hz, and the origin of damping is attributed to point defects within the 90°domain wall.
Abstract: The oscillation of domain walls caused by alternating fields is often thought to be the origin of dielectric losses. In this paper the physical nature of losses is explained by the damping of moving 90° domain walls. For frequencies up to 108 Hz the origin of damping of the wall motion is ascribed to point defects within the 90° domain wall. At high frequencies damping results from the reflection of thermal‐lattice waves impinging on a moving 90° domain wall.
60 citations
TL;DR: In this paper, the structural and dielectric properties of 0.1Pb0.9K0.95-xPbZrO3-(0. 9-x)PbTio3 solid solutions in the region of morphotropic phase boundary between tetragonal and rhombohedral structures were studied.
Abstract: The structural and dielectric properties have been studied on 0.1Pb0.9K0.1(Zn1/3Nb2/3)O2.95–xPbZrO3–(0.9-x)PbTio3 solid solutions in the region of morphotropic phase boundary between tetragonal and rhombohedral structures. In the X-ray analysis, the{200} reflections which were mainly selected to investigate are split into three lines, in which two are due to the tetragonal structure and central one is due to the rhombohedral structure in the miscibility gap between x=0.43~0.55. The phase boundary between two structures is not a line but a region, where the lattice parameters of each phase remain constant. In the dielectric study, the appearance of two phases is also investigated, being based on the "mixing rule" from the volume fractions and the dielectric constants of two phases. The Curie temperature of each phase does not change in the coexistence region of two phases.
50 citations
TL;DR: In this paper, the presintered layer structure bismuth compounds of PbBi2Nb2O9, Na0.5Bi4.5Ti4O15 and Pb2Bi4Ti5O18 are hot-worked by press forging under the maximum load of 200 kg/cm2 at a temperature of 1000°C to 1200°C.
Abstract: The presintered layer structure bismuth compounds of PbBi2Nb2O9, Na0.5Bi4.5Ti4O15, PbBi4Ti4O15 and Pb2Bi4Ti5O18 are hot-worked by press forging under the maximum load of 200 kg/cm2 at a temperature of 1000°C to 1200°C. The reduction ratio of height is more than 70%. The well-oriented polycrystalline samples with an orientation degree of more than 0.8 can be obtained. The measured results of dielectric and ferroelectric properties are correlated with SEM observations and x-ray diffractions.
45 citations
TL;DR: In this article, gas-gun impact techniques have been used to pulse charge nanofarad capacitors from the shock depoling of PZT 56/44 and pZT 95/5 ferroelectric ceramics.
Abstract: Gas‐gun impact techniques have been used to pulse charge nanofarad capacitors from the shock depoling of PZT 56/44 and PZT 95/5 ferroelectric ceramics. The PZT materials were depoled in the normal mode. Pulse powers of hundreds of kilowatts were produced in a few microseconds. The PZT 56/44 material was impacted in the stress range from 4.4 to 11.8 GPa. A maximum load voltage of 55 kV was produced at 7.9 GPa, resulting in a charge release of about 78%. Shock‐induced electrical breakdown in the PZT material occurred at 11.8 GPa. The PZT 95/5 material was impacted at 1.4 and 2.9 GPa stress levels. A maximum load voltage of 81 kV was produced at the higher stress, resulting in a charge release of about 74% before electrical breakdown occurred in the PZT material.
32 citations
TL;DR: In this article, a wide range of compositions of hot-pressed mixed oxide PLZT ferroelectric ceramics, covering both the rhombohedral and tetragonal phases, have been investigated.
Abstract: Piezoelectric properties of a wide range of compositions of hot-pressed mixed oxide PLZT ferroelectric ceramics, covering both the rhombohedral and tetragonal phases, have been investigated. The values of the electromechanical coupling constant, kp, were observed to range from 0.25 to 0.72. The values of the piezoelectric strain constant, d33, were observed to range from 76-710 × 10-12 C/N, Systemic variation of the Zr/Ti ratio and the La-concentration were discussed.
14 citations
TL;DR: In this article, the relation between mechanical strength and the ferroelectric state of the material has been determined and the effect on the strength of different kinds of defects which are formed during hardening, γ-irradiation, and polarization has been studied.
Abstract: Strength characteristics of ferroelectric ceramics possessing various internal biasing field values have been studied and the relation between mechanical strength and the ferroelectric state of the material has been determined. Anisotropy of the polarized ferroelectric ceramics mechanical strength has been studied. The effect on the strength of different kinds of defects which are formed during hardening, γ-irradiation, and polarization has been studied.
12 citations
TL;DR: In this article, the authors considered the optical induced birefringence change (OIBC) in PLZT in view of space charge formed by photoexcitation of carriers and showed that complete screening of the applied field by space-charge field does not occur.
Abstract: Optically induced birefringence change (OIBC) in PLZT is considered in view of space charge formed by photoexcitation of carriers. On the basis of optical measurements it is shown that, in general, complete screening of the applied field by space-charge field does not occur. Experimental results confirm theoretical calculations of electric fields and currents related to OIBC on the basis of a one-dimensional model.
10 citations
TL;DR: In this article, the coupled electromechanical responses of poled ferroelectric ceramics were considered and the boundary-initial value problems were solved using Laplace transform technique, and numerical inversions of the transform solutions were obtained by utilizing the method outlined by Luke and Salzer.
Abstract: In this paper we consider the coupled electromechanical responses of poled ferroelectric ceramics. Our considerations are linear as well as one dimensional. The constitutive relations which characterize the stress and the electric field in terms of the strain and the electric displacement reflect the fact that the responses of such a material are time dependent. These time dependent processes arise principally because domain switching, due to mechanical loadings and the application of external electric fields, does not occur instantaneously as well as due to other mechanical and electrical relaxation effects. We then formulate the boundary-initial value problems which correspond to the voltage mode, finite resistance, and pulse poling and depoling experiments. These problems are solved using Laplace transform technique, and numerical inversions of the transform solutions are obtained by utilizing the method outlined by Luke and Salzer.
7 citations
TL;DR: In this paper, the dielectric properties of PZT 95/5 were examined at high pressures using a tetrahedral anvil apparatus, and the authors attempted to provide these data by determining the small signal and high electric field dielectrics properties at pressures over 4 GPa.
Abstract: The dielectric properties of PZT 95/5 were examined at high pressures using a tetrahedral anvil apparatus. This ceramic has practical applications as a power source in which large quantities of charge are released by dynamic (shock wave) depolarization. Numerous mathematical models of this process have been proposed; however, the use of models has been limited because of the lack of high pressure electrical properties. This study attempted to provide these data by determining the small signal and high electric field dielectric properties at pressures over 4 GPa.
6 citations
TL;DR: In this paper, the electric field produced in a ferroelectric ceramic disk polarized in the axial direction when it is subjected to uniform transient loading over one of its planar surfaces was investigated.
Abstract: We investigate the electric field produced in a ferroelectric ceramic disk polarized in the axial direction when it is subjected to uniform transient loading over one of its planar surfaces. It is shown that the structure of the electric field depends on the instantaneous piezoelectric response, the degradation of the piezoelectric response due to the time dependent effects of depoling, and the structure of the mechanical disturbance. For the situation when electric field‐strain relaxation is much faster than stress‐strain relaxation, the voltage obtained by integrating the calculated electric field is in excellent qualitative agreement with the observed behavior of PZT 65/35.
TL;DR: In this paper, a model of positive temperature coefficient of resistance in ferroelectric ceramics is proposed, where a potential barrier is found by electrons in a bound state near oxygen vacancies.
Abstract: A model of positive temperature coefficient of resistance in ferroelectric ceramics is proposed. In the grain boundary region a potential barrier is found by electrons in a bound state near oxygen vacancies.Interaction between the trapped electrons and polarization results in stabilization of phase fluctuation, appreciable deepening of the impurity level and its strong dependence on temperature.
01 Jul 1978
TL;DR: In this article, a comparative study with the results obtained during a Ferroelectric-antiferroelectric or ferroelectricparaelectric phase transition with rising temperature is achieved.
Abstract: 2014 Thermoelectric converters using ferroelectric ceramics are described in this paper. The large loss of the remanent polarization during a phase transition with rising or decreasing temperature is used in these converters. The principle of operation is reported ; experimental results, experimental and theoretical efficiencies are given for a ferroelectric-antiferroelectric phase transition during a drop in temperature. A comparative study with the results obtained during a ferroelectric-antiferroelectric or ferroelectric-paraelectric phase transition with rising temperature is achieved. REVUE DE PHYSIQUE APPLIQUEE TOME 13, JUILLET 1978. Classification Physics Abstracts 77.70 77.80
TL;DR: In this article, the possibility of improving the parameters of a controlled thin-film resistor with memory, deposited on a ferroelectric substrate, was studied, and it was shown that the photoelectric properties of the semiconductor film are changed under the influence of the substrate.
Abstract: The possibility of improving the parameters of controlled thin film resistor with memory, deposited on a ferroelectric substrate was studied. It is shown that the photoelectric properties of the semiconductor film are changed under the influence of the ferroelectric substrate.
TL;DR: In this article, the ferroelectric field effect has been observed in a semiconducting thin film of n-type In2O3 deposited on a Pb(Zr, Ti)O3 ceramic substrate.
Abstract: The ferroelectric field effect has been observed in a semiconducting thin film of n-type In2O3 deposited on a Pb(Zr, Ti)O3 ceramic substrate. Typical resistivity values are approximately 11.8 ohm-cm for the depoled state, 0.56 ohm-cm for the carrier enhancement state (ON state) and 2500 ohm-cm for the depleted carrier state (OFF state). Resistivity “ON-OFF” ratios as high as 5 × 103 have been observed. The resistivity change from enhancement to depletion is large enough to be useful, however this device is lacking in long term stability.
TL;DR: In this article, the eigenstate space of the coupling factor is compared with the elastic space, Thermodynamic passivity generates inequalities and the maximum coupling factor has been found, for sub-maximum coupling factors the coincidence of the elastic and coupling eigenstates is partly proved, but evidence indicates the relation is satisfied.
Abstract: Eigenvalues and states of the elasticity matrix SE are calculated for poled ferroelectric ceramics. The eigenstate space of the coupling factor is compared with the elastic space, Thermodynamic passivity generates inequalities and the maximum coupling factor is found. The thermodynamic limit of maximum coupling factor introduces an additional equation, used to express the ratio d33/d33 in elastic coefficients. For sub-maximum coupling factors the coincidence of the elastic and coupling eigenstates is partly proved, but evidence indicates the relation is satisfied.