Browsing by Author "Jones, JL"
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- ItemDomain wall and interphase boundary motion in a two-phase morphotropic phase boundary ferroelectric: Frequency dispersion and contribution to piezoelectric and dielectric properties(American Physical Society, 2012-07-12) Jones, JL; Aksel, E; Tutuncu, G; Usher, TM; Chen, J; Xing, XR; Studer, AJIn ferroelectric materials, enhanced dielectric and piezoelectric property coefficients are found in compositions near morphotropic phase boundaries (MPBs). The material response in these compositions may be contributed by enhanced intrinsic piezoelectric distortions or increased interface motion, e.g., contributions from domain wall and interphase boundary motion, though the relative effect of these mechanisms in different materials is not yet well understood. One of the major challenges to developing this understanding is the availability and sensitivity of in situ characterization techniques, particularly during the application of cyclic electric fields of subcoercive or weak amplitude, conditions at which the property coefficients are measured. Here, we use time-resolved neutron diffraction to resolve the subtle electric-field-induced crystallographic strain mechanisms in a prototypical MPB composition, 36%BiScO(3)-64%PbTiO(3), that contains coexisting monoclinic and tetragonal phases. We observe multiple cooperative electromechanical effects including domain wall motion in both the monoclinic and tetragonal phases, interphase boundary motion between the two phases, and electric-field-induced lattice strains. The measured effects span four orders of magnitude in frequency, facilitating the discrimination of intrinsic and extrinsic contributions to properties. Domain wall motion in the monoclinic phase dominates the response, leading to shifts of diffraction peaks as high as 2300 pm/V; these shifts reflect the field-induced changes in average pseudocubic (00h) lattice spacing of the monoclinic phase parallel to the electric field. Domain wall motion in the tetragonal phase is also readily apparent and exhibits a degree of frequency dispersion similar to that measured in both the relative permittivity and piezoelectric coefficients at similar conditions. © 2012, American Physical Society.
- ItemFerroelastic contribution to the piezoelectric response in lead zirconate titanate by in situ stroboscopic neutron diffraction(Elsevier B. V., 2006-11-15) Jones, JL; Hoffman, M; Daniels, JE; Studer, AJFerroelastic domain switching during dynamic actuation is measured in situ for a piezoelectric lead zirconate titanate (PZT) ceramic utilizing a new capability developed on The Australian Strain Scanner (TASS) at ANSTO. Diffraction patterns are obtained as a function of time during a 1 Hz cycle. The change in the 0 0 2 and 2 0 0 diffraction intensities indicates there is ferroelastic domain switching at sub-coercive (weak) fields. © 2006 Elsevier B.V.
- ItemFerroelastic domain switching fatigue in lead zirconate titanate ceramics(Elsevier, 2008-04) Pojprapai, S; Jones, JL; Studer, AJ; Russell, J; Valanoor, N; Hoffman, MThe influence of the frequency and amplitude of cyclic mechanical loading on soft, tetragonal lead zirconate titanate (PZT) ceramics was investigated via neutron diffraction. Intensity change in the {2 0 0} reflections provided quantitative measurements of domain switching behavior, domain texture and the strain resulting from domain switching. The results are explained using a viscoelasticity model. It was found that the magnitude of applied stress affects the level of strain accumulated, while its frequency affects the time taken for the strain to reach saturation. Furthermore, markedly different behaviors are exhibited by poled and unpoled samples. For samples loaded under identical conditions, the frequency effect is more pronounced in unpoled samples and the accumulated ferroelastic strain is greater in poled samples. © 2008, Elsevier Ltd.
- ItemAn in situ diffraction study of domain wall motion contributions to the frequency dispersion of the piezoelectric coefficient in lead zirconate titanate(American Institute of Physics, 2013-01-28) Seshadri, SB; Prewitt, AD; Studer, AJ; Damjanovic, D; Jones, JLThe contribution of non-180 degrees domain wall displacement to the frequency dependence of the longitudinal piezoelectric coefficient has been determined experimentally in lead zirconate titanate using time-resolved, in situ neutron diffraction. Under subcoercive electric fields of low frequencies, approximately 3% to 4% of the volume fraction of non-180 degrees domains parallel to the field experienced polarization reorientation. This subtle non-180 degrees domain wall motion directly contributes to 64% to 75% of the magnitude of the piezoelectric coefficient. Moreover, part of the 33 pm/V decrease in piezoelectric coefficient across 2 orders of magnitude in frequency is quantitatively attributed to non-180 degrees domain wall motion effects. © 2013, American Institute of Physics.
- ItemIn situ neutron diffraction studies of a commercial, soft lead zirconate titanate ceramic: response to electric fields and mechanical stress(Springer, 2010-03-20) Pramanick, A; Prewitt, AD; Cottrell, MA; Lee, W; Studer, AJ; An, K; Hubbard, CR; Jones, JLStructural changes in commercial lead zirconate titanate (PZT) ceramics (EC-65) under the application of electric fields and mechanical stress were measured using neutron diffraction instruments at the Australian Nuclear Science and Technology Organisation (ANSTO) and the Oak Ridge National Laboratory (ORNL). The structural changes during electric-field application were measured on the WOMBAT beamline at ANSTO and include non-180° domain switching, lattice strains and field-induced phase transformations. Using time-resolved data acquisition capabilities, lattice strains were measured under cyclic electric fields at times as short as 30 μs. Structural changes including the (002) and (200) lattice strains and non-180° domain switching were measured during uniaxial mechanical compression on the NRSF2 instrument at ORNL. Contraction of the crystallographic polarization axis, (002), and reorientation of non-180° domains occur at lowest stresses, followed by (200) elastic strains at higher stresses. © 2010, Springer.
- ItemIntrinsic and extrinsic contributions to the piezoelectric effect in soft lead zirconate titanate (PZT) ceramics by time-resolved neutron diffraction(The Bragg Institute, Australian Nuclear Science and Technology Organisation, 2005-11-27) Jones, JL; Daniels, JE; Studer, AJ; Hoffman, M; Finlayson, TRPiezoelectric ceramics are used in biomedical, naval, micromechanical, and many other precision engineering applications and therefore require a well-characterized, stable response. Utilizing a new capability developed on the The Australian Strain Scanner (TASS) at ANSTO, we have directly measured in situ the intrinsic and extrinsic t contributions to the piezoelectric effect in soft lead zirconate titanate (PZT) ceramics. The 002 and 200 diffraction peaks are measured as a function of time using a stroboscopic technique which enables timing resolutions of less than 30us. In other words, we have measured the 200 and 002 peak profiles as a function of time during piezoelectric activation. In this tetragonal crystal structure, a comparison of the 002 and 200 integrated intensity yields the non-180° domain switching contribution (extrinsic) while shifting of the peaks yields the change in 001 and 100 lattice strains (intrinsic). Both components lead to the macroscopic strain measured as the piezoelectric response, which is found to be a function of frequency and applied electric field. These results go toward explaining the nonlinearities of piezoelectric response versus frequency and magnitude of driving field measured in earlier work. © The Authors
- ItemMeasurement and analysis of field-induced crystallographic texture using curved position-sensitive diffraction detectors(Springer Nature, 2014-02-09) Simons, H; Daniels, JE; Studer, AJ; Jones, JL; Hoffman, MThis paper outlines measurement and analysis methodologies created for determining the structural responses of electroceramics to an electric field. A sample stage is developed to apply electric fields to ceramic materials at elevated temperatures during neutron diffraction experiments. The tested voltages and temperatures range from −20 kV to +20 kV and room temperature to 200 °C, respectively. The use of the sample environment for measuring the response of ferroelectric ceramics to an electrical stimulus is demonstrated on the instrument Wombat, a monochromatic neutron diffractometer employing a curved positive sensitive detector. Methodologies are proposed to account for the geometrical effects when vector fields are applied to textured materials with angularly dispersive detector geometries. Representative results are presented for the ferroelectric (Bi1/2Na1/2)TiO3-6%BaTiO3 (BNT-6BT) which show both phase transformation and ferroelectric domain texturing under the application of an electric field. This experimental and analysis approach is well suited for time-resolved measurements such as stroboscopic and in situ studies on a variety of electro-active materials.© 2014, Springer Science+Business Media New York.
- ItemNeutron diffraction study of the polarization reversal mechanism in [111](c)-oriented Pb(Zn1/3Nb2/3)O-3-xPbTiO(3).(American Institute of Physics, 2007-05-24) Daniels, JE; Finlayson, TR; Davis, M; Damjanovic, D; Studer, AJ; Hoffman, M; Jones, JLThe polarization reversal mechanism in [111](c)-oriented Pb(Zn1/3Nb2/3)O-3-xPbTiO(3) has been investigated by in-situ neutron diffraction. Stepwise static-field measurements of the (222)(c) rocking curves confirm a two-stage polarization reversal mechanism via a sequence of non-180 degrees domain reorientations. The time-resolved response has also been measured upon application of a bipolar square wave with a 30 s period to observe directly the relaxation times of diffracted neutron intensity during the reversal process. Upon application of a large antipolar field, the diffraction intensity increases quickly, before relaxing over a longer time period with an exponential decay constant, tau, of approximately 5.7 s. These large time constants correlate with a frequency dependence of the macroscopic strain-field response. © 2007, American Institute of Physics
- ItemOrigin of large recoverable strain in 0.94(Bi0.5Na0.5)TiO3-0.06BaTiO3 near the ferroelectric-relaxor transition(America Institute of Physics, 2013-02-11) Simons, H; Daniels, JE; Glaum, J; Studer, AJ; Jones, JL; Hoffman, MPiezoceramics of composition 0.94(Bi(0.5)Na(0.5))TiO(3)-0.06BaTiO(3) demonstrate large recoverable strain at elevated temperature (T > 75 degrees C), which is absent at room temperature. In situ neutron diffraction was used to measure changes in the crystallographic and domain structures during electric field application at temperatures ranging from 25 degrees C to 100 degrees C. Quantitative evaluation of the ferroelastic domain volume fraction in the field-induced phases enabled calculation of the strain contribution from non-180 degrees domain switching. The large recoverable strain is shown to be associated with the reversible nature of the phase transformation. These findings have implications to additional BNT-xBT-based composition and other relaxor ferroelectrics. © 2013, American Institute of Physics
- ItemQuantitative comparison between the degree of domain orientation and nonlinear properties of a PZT ceramic during electrical and mechanical loading(Cambridge University Press, 2011-05-01) Marsilius, M; Granzowa, T; Jones, JLThe macroscopic electromechanical coupling properties of ferroelectric polycrystals are composed of linear and nonlinear contributions. The nonlinear contribution is typically associated with the extrinsic effects related to the creation and motion of domain walls. To quantitatively compare the macroscopic nonlinear properties of a lead zirconate titanate ceramic and the degree of domain orientation, in-situ neutron and high-energy x-ray diffraction experiments are performed and they provide the domain orientation density as a function of the external electric field and mechanical compression. Furthermore, the macroscopic strain under the application of external electrical and mechanical loads is measured and the nonlinear strain is calculated by means of the linear intrinsic piezoelectric effect and the linear intrinsic elasticity. The domain orientation density and the nonlinear strain show the same dependence on the external load. The scaling factor that relates to the two values is constant and is the same for both electrical and mechanical loadings. © 2011, Cambridge University Press
- ItemTime-resolved diffraction measurements of electric-field-induced strain in tetragonal lead zirconate titanate(American Institute of Physics, 2007-05-01) Daniels, JE; Finlayson, TR; Studer, AJ; Hoffman, M; Jones, JLThe dynamic electric-field-induced strain in piezoelectric ceramics enables their use in a broad range of sensor, actuator, and electronic devices. In piezoelectric ceramics which are also ferroelectric, this macroscopic strain is comprised of both intrinsic (piezoelectric) and extrinsic (non-180 degrees domain switching) strain components. Extrinsic contributions are accompanied by hysteresis, nonlinearity, and fatigue. Though technologically significant, direct measurement of these mechanisms and their relative contributions to the macroscopic response has not yet been achieved at driving frequencies of interest. Here we report measurements of these mechanisms in ceramic lead zirconate titanate during application of subcoercive cyclic driving electric fields using an in-situ stroboscopic neutron diffraction technique. Calculations are made from the diffraction measurements to determine the relative contributions of these different strain mechanisms. During applied electric field square waves of +0.5E(c) unipolar and +/- 0.5E(c) bipolar, at 1 Hz, non-180 degrees domain switching is found to contribute 34% and 40% of the macroscopically measured strain, respectively. © 2007, American Institute of Physics
- ItemTime-resolved studies of ferroelectric materials using Neutron Stroboscopic techniques during the application of electric fields(Australian Institute of Physics, 2006-12-05) Daniels, JE; Finlayson, TR; Studer, AJ; Jones, JLAn experimental facility utilising stroboscopic methods has been developed at the Australian Nuclear Science and Technology Organisation and has been applied to study the time dependence of neutron Bragg peak intensities, in response to applied high-voltage electric fields. One advantage of such methods is that relatively small changes in scattering intensity which may occur in materials as the result of the application of a stimulus such as electric field, can be enhanced. The present stroboscopic facility with a timing resolution below 20μs, has been applied to study the variation of Bragg peak intenstities from ferroelectric materials such as triglycine sulphate (TGS), a common pyroelectric detector material, and lead zirconate titanate (PZT), the most widely used material for electromechanical transducer applications. The results obtained show the first insight into the real-time structural response of these materials during dynamic electrical loading. Single crystal TGS shows very interesting structural behaviour in the first two hundred microseconds of switching of field intensity, which is apparent in large relaxation effects in the diffracted intensity of particular hkl reflections. For the ceramic PZT, both intrinsic (lattice strains) and extrinsic (domain wall motion) contributions to the macroscopic strain have been identified from the measurement of changes in Bragg peak intensities, for the first time, during dynamic actuation.