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Applications of Ferroelectrics, 1992. ISAF '92., Proceedings of the Eighth IEEE International Symposium on

Date Aug. 30 1992-Sept. 2 1992

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  • Proceedings of 1992 IEEE International Symposium on Applications of Ferroelectrics

    Publication Year: 1992
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    Freely Available from IEEE
  • The relation between the Mg concentration threshold effect and the defect structures of the congruent Mg:LiNbO3

    Publication Year: 1992 , Page(s): 43 - 46
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    Congruent Mg:LiNbO3 with Mg concentration of 0, 1.0, 2.7, 5.0, and 6.0 mo 1% has been prepared. A set of defect models consistent with density measurement is proposed. When the Mg concentration (Mg) exceeds a critical value (Mg)c, Nb-site Mg in the form of MgLiMgNb(1/3/)Nbsub Nb(2/3)/O3 appears in the crystal. The (Mg)c varies as the Li/Nb ratio of the crystal and should be 5.30 mo 1% for the congruent crystal. It is suggested that the optical absorption by the reduced crystals is due to defects comprising both F centers, formed under reduction, and different types of dipolarons. When (Mg) exceeds (Mg)c, (Mg Li-MgNb)-F-(MgLi-NbN) occurs in the reduced crystal, which causes an abrupt change in the optical absorption of the crystal View full abstract»

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  • Chemically prepared Pb(Zr,Ti)O3 thin films: the effects of orientation and stress

    Publication Year: 1992 , Page(s): 344 - 348
    Cited by:  Papers (4)  |  Patents (1)
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    The effects of orientation and stress on chemically prepared Pb(Zr,Ti)O3 (PZT) film properties have been determined. Systematic modification of the underlying substrate technology has made it possible to fabricate suites of films that have various degrees of orientation at a constant stress level, and to fabricate films that are in different states of stress but have similar orientation. Highly oriented films of the following compositions have been fabricated: PZT 60/40, PZT 40/60, and PZT 20/80. Remanent polarizations (≈60 μC/cm 2) greater than those of the best bulk polycrystalline ferroelectrics were obtained for PZT 40/60 films that were under compression and highly (001) oriented. Systematically varying orientation influenced ferroelectric properties, and the film stress also had a considerable effect. The sign of the film stress at the Curie point controlled the type of ferroelectric behavior exhibited by the films. Stress measurements as a function of thermal history indicated that the coefficient of thermal expansion of the paraelectric state was critical in determining the type of film ferroelectric behavior View full abstract»

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  • Poling and switching behavior of ferroelectric single grains studied by piezoelectric resonance

    Publication Year: 1992 , Page(s): 367 - 369
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    A piezoelectric resonance signal from a minute (~10 μg) single-grain ferroelectric sample was observed using an inductive pulse detection method (IPDM). The IPDM does not require electrodes to be coated on the samples and is suitable for small samples. Examples of temperature-dependent resonance signals from Rochelle salt, KH2 PO4 (KDP), and NH4H2PO4 (ADP) single grains are shown. The poling and switching behavior of a single grain of Rochelle salt in an external electric field is studied. The time dependence of the resonance frequency and decay time constant of the transient piezoelectric resonance signal reflects the change in sample polarization due to variation of domain structure. Another advantage of the IPDM is its capability of observing fast initial change just after the application of electric field. The in-situ detection characteristic is facilitated by the well-isolated detection and poling systems inherent to inductive methods View full abstract»

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  • DAAS technique for synthesizing doped PZT and PLZT thin films

    Publication Year: 1992 , Page(s): 349 - 352
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    The deposition by aqueous acetate solution (DAAS) technique has been developed for the preparation of 5% Fe-doped Pb(Zr0.53Ti 0.47)O3 (PZT) and (Pb0.93La0.07 )(Zr0.65Ti0.35)0.983O 3 (PLZT) thin films on Pt⟨111⟩/Ti/SiO2/Si substrates. PZT films, crystallized at 600°C for 10 min, display good electrical properties and fatigue characteristics. Iron doping suppressed the crystallization of the films as measured by X-ray diffraction (XRD) and Fourier-transform infrared (FTIR) spectroscopy. When 5% of the zirconium and titanium were replaced by iron in the stoichiometric precursor solution, the film crystallized predominantly in the (110) orientation. When 5% excess iron was added to the precursor solution, the film crystallized in the (100) orientation. The electronic states and charge species responsible for photoconductivity were investigated by emission/excitation and photocurrent action spectroscopy. The low photoemission at 77 K and high photoconductivity at 298 K in the doped thin films, as compared with thermally iron-doped ceramics, are attributed to surface energy quenching and low trapping state density View full abstract»

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  • Processing and characterization of new members of Pb-K-niobate series

    Publication Year: 1992 , Page(s): 374 - 376
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    It is shown that by mixing the two ferroelectric compounds lead niobate and potassium niobate in different proportions a whole set of new materials can be obtained. Some of these compositions are found to be ferroelectric in nature and behave in accordance with the amount of potassium doping in the lead niobate. The new materials have the general formula of Pb1-xK2xNb2O6. Four new members of this class of materials have been processed, with x values of 0.23, 0.34, 0.43, and 0.50. The densified ceramic samples have been characterized, and it has been found that the first two are ferroelectric while the other two are not. Results for PKN with x=0.23 and x=0.34 are tabulated in comparison with the standard material with x=0.20 View full abstract»

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  • The analytic representation of the effective nonlinear coefficients for biaxial crystals in the coordinate planes

    Publication Year: 1992 , Page(s): 31 - 34
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    Analytical expressions for the effective second-order nonlinear coefficients for type-I and type-II phase matching for five groups of biaxial crystals in the coordinate planes of the optical ellipsoid are presented. Using these expressions, the coefficient value can be derived easily without numerical calculation for every point in the phase matching curves View full abstract»

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  • The effect of dysprosium on the microstructure and dielectric properties of (Ba1-xSrx)TiO3 ceramics

    Publication Year: 1992 , Page(s): 51 - 54
    Cited by:  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (528 KB)  

    A study was performed on the microstructure and dielectric properties of barium strontium titanate ceramics having the compositions (Ba1-xSrx)TiO3, and (Ba0.99-xSrxDy0.01)TiO3 with x in the range from 0 to 0.3. In all cases, the addition of dysprosium resulted in a marked reduction in grain size, from ≈50 μm to ≈1 μm, which was accompanied by a substantial increase in permittivity below the Curie temperature. The peak in permittivity at the Curie point was strongly suppressed by Dy-doping, and the phase transition range became broad and diffuse, particularly at the higher levels of strontium. TEM (transmission electron microscope) observations of a high density of dislocations and an inhomogeneous distribution of strontium within the grains suggest that the chemical segregation of strontium is largely responsible for this diffuse phase transition behavior View full abstract»

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  • The influence of La content in PLZT-x/95/5 ceramics (x =0.5 to 4%) on the dielectric, pyroelectric, thermally stimulated current and Raman scattering measurements and model interpretation

    Publication Year: 1992 , Page(s): 370 - 373
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    PLZT (lead lanthanum zirconate titanate) x/95/5 ceramics with low La concentration, x=0.5 to 4 wt.%, exhibit an antiferroelectric (AFE)-ferroelectric (FE)-paraelectric (PE) phase sequence. The FE phase exists in both AFE and PE phases in a wide range. Dielectric, pyroelectric, thermally stimulated current, and Raman scattering measurements have been performed as functions of temperature in all phases. The diffuse character of the phase transitions was confirmed, and the width of the phases coexistence was proved to depend on the La concentration. A model is proposed for interpreting the defects and the phase balance View full abstract»

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  • The use of design of experiments to evaluate the reliability of ferroelectric nonvolatile memories

    Publication Year: 1992 , Page(s): 416 - 419
    Cited by:  Papers (2)
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    A full factorial experiment was performed on 4 K ferroelectric random access memory (FRAM) devices to determine their fatigue performance as a function of fatigue temperature, fatigue voltage, read/write voltage, pattern, and number of cycles of fatigue. The resulting response surface of short-term retention (10 s at 80°C) and long-term retention (40 h at 100°C) and the product functionality were the metrics used to evaluate the product performance. An empirical model was used to predict yields and product performance. Based on this model, process modifications were undertaken to improve the performance of the product fabricated with PZT (nominal composition: Pb1.10Zr0.48Ti0.52O3. As a result, better than two-orders-of-magnitude improvement in product performance over operating conditions was seen. In addition, a statistically based monitoring program has been developed to ensure product performance View full abstract»

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  • Measurement of electro-optic coefficient of ferroelectric PLZT thin films

    Publication Year: 1992 , Page(s): 233 - 235
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    A novel and simple technique using a magnetooptical modulator based on the Faraday effect is proposed for measuring the electrooptic coefficient (EO) of ferroelectric PLZT (La-doped lead zirconate titanate) thin films. This technique measures phase retardation shift by determining the frequency change of the modulated light. The main error of the measuring system comes from reading goniometers with a precision of 10-5 radians. Thus, the measurable retardation of the optical path is the order of a few angstroms. Experimental results are presented for thin ferroelectric PLZT films made by magnetron sputtering. The quadratic EO coefficient of the PLZT films varies in the range of 0.1×10-16 to 1.0×10-16 (m/v) 2, depending on the sputtering conditions View full abstract»

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  • Quasi lumped parameter method for microwave measurements of dielectric dispersion in ferroelectric ceramics

    Publication Year: 1992 , Page(s): 480 - 483
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    A modified lumped parameter method is discussed which is judged to be especially suitable for microwave measurements of dielectric dispersion in high dielectric materials in a particular frequency region. The method combines some of the features of the lumped parameter method and the distributed parameter method. Dielectric dispersions for PbZr1-xTixO3, BaTiO3, and Ba xSr1-xTiO3 ceramics in the frequency domain from 1 MHz to 1 GHz are presented. The principle of the measurement and the accuracy of the experimental data which are retrieved are also discussed View full abstract»

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  • Development of portable DC voltage standard using PZTs

    Publication Year: 1992 , Page(s): 554 - 555
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    A simple, portable DC voltage standard has been developed, using poled PZT (lead zirconate titanate) with the application of a charge recovery process. The charge decay is due to compensating charges coming to the PZT surfaces from the atmosphere and/or by electrical loading of the PZT, and these charges screen the intrinsic PZT charge. The maximum open circuit voltage of the PZT has been recovered and measured with an accuracy of ±10 μV. It was also confirmed that the PZT DC voltage source remained constant at different places View full abstract»

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  • Automated system for processing of PLZT powders derived from acetate precursors

    Publication Year: 1992 , Page(s): 484 - 487
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    An IBM-PC-based system for producing and controlling the production of PLZT (lead lanthanum zirconate titanate) powders from water-soluble acetate precursors is described. Problems with the development of appropriate sensing systems and algorithms are discussed. A proposed prototype system is presented. An automated batching system will be run by an expert system in such a manner in that when the desired composition of the PLZT acetate solution to be made is entered, the process will be changed to yield the correct amounts of each constituent needed View full abstract»

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  • Pyrochlore/perovskite phase transformation in lead zinc-niobate based ceramics

    Publication Year: 1992 , Page(s): 377 - 380
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    A phase transformation from pyrochlore to perovskite takes place during the firing of Pb(Zn1/3Nb2/3)O3 (PZN)-based ceramics. Stabilization of the perovskite phase in PZN-based ceramics is closely related to the type of additive and its amount. A thermodynamic model based on the chemical potential of the system that accounts for the stabilization of the perovskite phase in terms of the internal stress introduced by the additives is proposed. The additives that stabilize the perovskite phase in PZN-based ceramics are those materials that can initiate the formation of perovskite subgrains View full abstract»

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  • Influence of high energy grinding on the texture, structure and electrical properties of barium titanate

    Publication Year: 1992 , Page(s): 398 - 400
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    It is shown that nanocrystalline barium titanate can be obtained from high-energy ball-milling of conventional commercially available barium titanate powder. X-ray investigations, surface determination, and dielectric studies have been carried out on several samples obtained with different periods of grinding. It is found that stabilization of the cubic phase at room temperature occurs for values of grain size and coherently diffracting domain size lower than 0.12 μm and 2.5×102 Å, respectively View full abstract»

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  • Domain investigations: a select review

    Publication Year: 1992 , Page(s): 171 - 178
    Cited by:  Patents (2)
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    The author points out that practically all macroscopic properties of ferroelectrics are extensively influenced by their domain structures, though the mechanisms involved vary. He first surveys the role of domains, whether advantageous or detrimental, in practical devices. He then presents a review of recent progress in selected areas of research, namely, the role of ferroelasticity in the formation of domain structures (2-D and 3-D constraints), domain-wall-conditioned permittivity, and the high-field dielectric response of ferroelectric lock-in phases. Some areas for further investigation are also discussed View full abstract»

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  • Pure and modified lead titanate thin films by sol-gel

    Publication Year: 1992 , Page(s): 420 - 423
    Cited by:  Papers (2)
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    Pure and modified lead titanate thin films were fabricated by spin coating an alkoxide-based solution onto platinum-coated silicon substrates. The solution was made by combining lead acetate trihydrate, titanium IV isopropoxide, and diethanolamine in isopropanol with lanthanum as a dopant. Various heating schedules and techniques were examined to optimize the dielectric and microstructural properties of the films. The films were tested for dielectric and hysteresis properties, and characterized by various methods. Perovskite PbTiO3 was found to form at approximately 400°C and could be obtained by heating for short soaking durations of 10 min per layer. Measured at 1 kHz, an average dielectric constant of 410 was obtained for pure lead titanate films heated at 500°C for 1 h. Hysteresis measurements taken on these films at 100 Hz revealed an average remanent polarization of 11 μC/cm2 with a coercive field of approximately 75 kV/cm. The films doped with 5% lanthanum exhibited a dielectric constant of 825 with a coercive field of 52 kV/cm and a remanent polarization of 25 μC/cm2 View full abstract»

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  • Grain size effect on the dielectric properties of strontium barium titanate

    Publication Year: 1992 , Page(s): 55 - 58
    Cited by:  Papers (1)  |  Patents (2)
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    The effect of grain size on the dielectric properties of Sr0.2Ba0.8TiO3 (SBT) ceramic is reported. SBT powder prepared by a hydrothermal procedure was used in this study. A porous ceramic was prepared by sintering the powder compacts between 1100°C and 1350°C for 5 min-10 h, either by conventional sintering or by fast firing. When the average grain size of the ceramic was between 0.75 and 1.2 μm, the room temperature dielectric constant peaked to 5500-6000. In porous fine grain ceramic, classic P vs. E hysteresis behavior is observed. The etched and polished microstructure of fine grain porous ceramic showed multidomain characteristics View full abstract»

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  • Defect structures and fatigue in ferroelectric PZT thin films

    Publication Year: 1992 , Page(s): 244 - 247
    Cited by:  Papers (1)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (432 KB)  

    A thermally stimulated current (TSC) technique has been used to characterize natural and electric-field-induced defect distributions in PZT (lead zirconate titanate) films. The principal defects give rise to TSC peaks near 400 K and 500 K, with defect concentrations of about 10 21 cm-3 and an activation energy of about 0.8 eV. Changes in the defect structures as a function of the number of switching cycles and processing conditions are described, and their relationship to fatigue are discussed. It is suggested that the defects distributions measured by TSC arise from extended defects rather than from point defects. Domain splitting and pinning as a result of such defects generated during polarization reversals may account for fatigue in PZT films View full abstract»

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  • Domain orientation and piezoelectric properties of Ag doped PMN-PZT ceramics

    Publication Year: 1992 , Page(s): 144 - 147
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    The hysteresis, dielectric, and piezoelectric properties of ternary 0.5PMN-0.5-PZT (lead magnesium niobate-lead zirconate titanate) ceramics with Ag substitution are described. These ceramics show good square hysteresis loops and thus are promising for thin-film memory applications. At high Ag concentrations the dielectric loss decreased, indicating an increase in the ordering of the structure. A marked increase in the piezoelectric properties, particularly the thickness coupling factor and the piezoelectric charge coefficient, d33, was observed View full abstract»

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  • The effect of photo-refractively induced periodic strain grating on piezoelectric vibration in LiNbO3:Fe

    Publication Year: 1992 , Page(s): 156 - 159
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    Strong nonlinear behavior was observed in an LiNbO3:Fe piezoelectric resonator with a photorefractive periodic grating. The resonator is a y-cut plate with Au electrodes totally or partially deposited on both faces. The current-voltage and the admittance-frequency characteristics show nonlinear behavior such as hysteresis only near the resonance frequency. In some conditions, the current changes negatively with the voltage. These characteristics depend on the Q-value of the resonator. The present nonlinear phenomena do not occur when the Q-value is too large, while they occur at larger values of Q in usual resonators. It was found that the Q-value of the resonator with the photorefractive grating varied when the resonator was annealed or when the period of the grating was changed View full abstract»

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  • 90°-domain reversal in Pb(ZrxTi1-x)O3 ceramics

    Publication Year: 1992 , Page(s): 401 - 404
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    A simple and direct method is proposed which can be used for quantitatively distinguishing the mechanisms of domain reorientation processes in polycrystalline materials. Using this method, the 90° domain reorientation in Pb(ZrxTi1-x)O3 (PZT) ceramic under electric field was examined by X-ray diffraction analysis. It was found that the polarization switching in the PZT ceramic with a composition near the morphotropic phase boundary is predominantly controlled by two successive 90° domain processes rather than by 180° domain wall reversal. Experimental results also indicate that the coercive field of the ceramics is related to the cooperative deformation associated with each grain, which arises from the 90° domain reversal process View full abstract»

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  • Model of electrooptic effects by Green function and summary representation: applications to bulk and thin film PLZT displays and spatial light modulators

    Publication Year: 1992 , Page(s): 600 - 603
    Cited by:  Papers (1)
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    In order to understand electrooptic effects in single crystals or ceramic materials, it is necessary to know the optimum field distribution and to accurately determine the electrooptic parameters, including the half-wave voltage applied, so that accurate electrooptic coefficients can be obtained. For this purpose, three computational methods have been used: Green's function, iteration, and summary representation. The principle of the method of summary representations is described. Field distributions and electrooptic effects in ceramic bulk and thin-film materials have been calculated using this method. The method has been used to treat problems in PLZT (lead lanthanum zirconate titanate) bulk and thin-film displays/spatial light modulators View full abstract»

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  • Dielectric properties and crystal structures of entire compositions in the ternary system Pb(Mg1/2W1/2)O3-Pb(Ni1/3Nb 2/3)O3-PbTiO3

    Publication Year: 1992 , Page(s): 66 - 69
    Cited by:  Papers (1)
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    Crystal structures and dielectric properties were investigated over the entire range of composition in the system Pb(Mg1/2W 1/2)O3-Pb(Ni1/3 Nb2/3)O3-PbTiO3(PM A morphotropic phase boundary (MPB) was found on the compositional line with 45 to 50 mol.% PT content. The PT-rich composition with Tc>100°C showed a steep temperature dependence of the dielectric constant. The PMW-rich composition with Tc around room temperature or below showed a diffuse phase transition. Superlattice reflections due to the ordering of Mg and W ions in the perovskite B-site were observed in the X-ray diffraction patterns of the PMW-rich composition. The results obtained indicate that PMW-rich compositions were relaxor ferroelectric. A downward Curie temperature shift as a function of PMW content was saturated in the PMW-rich compositional region, which suggests that the PMW-rich region is not a simple solid solution but a nanometer composite of an ordered region and a disordered region View full abstract»

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