Sample records for relaxor ferroelectric behavior

  1. Dynamics of relaxor ferroelectrics

    Microsoft Academic Search

    R. Pir; R. Blin; V. Bobnar

    We study a dynamic model of relaxor ferroelectrics based on the spheri- cal random-bond—random-field model and the Langevin equations of motion written in the representation of eigenstates of the random interaction matrix. The solution to these equations is obtained in the long-time limit where the system reaches an equilibrium state in the presence of random local electric fields. The complex

  2. Effects of ordering degree on the dielectric and ferroelectric behaviors of relaxor ferroelectric Pb(Sc1/2Nb1/2)O3 ceramics

    NASA Astrophysics Data System (ADS)

    Zhu, Mankang; Chen, Chuan; Tang, Jianlan; Hou, Yudong; Wang, Hao; Yan, Hui; Zhang, Weihong; Chen, Jian; Zhang, Wenjun

    2008-04-01

    Relaxor ferroelectric Pb(Sc0.5Nb0.5)O3 ceramics were synthesized by a modified solid oxide reaction method. The x-ray diffraction and Raman scattering analysis affirmed that annealing dominated the ordering degree of PSN samples. The measurements on dielectric response and ferroelectric behavior indicate the prominent impact of the ordering degree. The dielectric response of a relaxor ferroelectric is determined by the growing and freezing behaviors of the polar regions, which is correlated with the ordering degree. In addition, the behavior of the ferroelectric phase transition was controlled by the lattice distortion in ordered domain due to the displacement of Pb and ferroelectrically active Nb cations in the PSN lattice.

  3. Nonlinearity of a composite relaxor ferroelectric transducer

    NASA Astrophysics Data System (ADS)

    Lu, Jian-yu; Song, Tai K.; Greenleaf, James F.; Oakley, Clyde G.

    1992-11-01

    Relaxor ferroelectric materials have been studied extensively in both theory and experiments for many years. Their applications to medical ultrasonic transducers have also been investigated. In this paper, we report an experimental study of a composite relaxor ferroelectric transducer and its nonlinear phenomenon at certain bias voltages. Novel applications of the relaxor transducer to diffraction-limited beam production, acoustic power measurement, low speckle medical imaging, and high resolution pulse-echo imaging are discussed.

  4. ``Dielectric relaxor'' behavior of electroactive fluorinated polymers

    NASA Astrophysics Data System (ADS)

    Ang, Chen; Yu, Zhi

    2005-06-01

    The dielectric spectra of poly(vinylidene fluoride-trifluoroethylene) copolymers and poly(vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene) terpolymers are studied in a wide temperature and frequency range with electric field. It is found that the dominant relaxation process displays a peculiar characteristic—a "dielectric relaxor" behavior, rather than a "ferroelectric relaxor" behavior reported in the current literature; furthermore, we show the experimental observation that the existence of nanometer scale crystals embedded in an amorphous matrix is the base of the dielectric relaxor behavior and high electroactive performance in these polymers.

  5. Effects of composition and temperature on the large field behavior of [011]{sub C} relaxor ferroelectric single crystals

    SciTech Connect

    Gallagher, John A.; Lynch, Christopher S., E-mail: cslynch@seas.ucla.edu [Department of Mechanical and Aerospace Engineering, University of California Los Angeles, 420 Westwood Plaza, Los Angeles, California 90095 (United States); Tian, Jian [H. C. Materials Corporation, 479 Quadrangle Dr., Suite-E, Bolingbrook, Illinois 60440 (United States)

    2014-08-04

    The large field behavior of [011]{sub C} cut relaxor ferroelectric lead indium niobate–lead magnesium niobate–lead titanate, xPb(In{sub 1/2}Nb{sub 1/2})O{sub 3}-(1-x-y)Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}-yPbTiO{sub 3}, single crystals was experimentally characterized in the piezoelectric d{sub 322}-mode configuration under combined mechanical, electrical, and thermal loading. Increasing the concentration of lead indium niobate and decreasing the concentration of lead titanate in compositions near the morphotropic phase boundary resulted in a decrease of mechanical compliance, dielectric permittivity, and piezoelectric coefficients as well as a shift from a continuous to a discontinuous transformation.

  6. Relaxor behavior of bismuth layer-structured ferroelectric ceramic with m=2

    NASA Astrophysics Data System (ADS)

    Du, Huiling; Li, Ying; Li, Huilu; Shi, Xiang; Liu, Cui

    2008-11-01

    In this paper, the crystal structure, dielectric and ferroelectric studies of PbBi 2Nb 2O 9 and Pb 0.8Ba 0.2Bi 2Nb 2O 9 ceramics are reported. X-ray structural studies along with Rietveld refinement confirmed it to be an m=2 member of the Aurivillius family of oxides and the refined lattice parameters are calculated. The orthorhombic distortion decreases with increasing dopant radius. The decrease of the orthorhombic distortion further causes a decrease of the Curie temperature. It can be inferred that substitution of Pb by the larger cation Ba 2+ would lead to a lower thermal energy for phase transition. Broad dielectric maxima, which shift to higher temperature with increasing frequency, and the value of the relaxation parameter ? which is above 1 (estimated from the linear fit of the modified Curie-Weiss law with other empirical parameters ?Tm, ?T) indicate the relaxor nature for PBBN ceramics. Well-developed P-E hysteresis loops are obtained from PBBN samples. The Pr values are improved to 10.5 ?C/cm 2 at 423 K when Ba 2+ is introduced into the PBN-based ceramic.

  7. Structure factor of a relaxor ferroelectric

    NASA Astrophysics Data System (ADS)

    Guzmán-Verri, G. G.; Varma, C. M.

    2015-04-01

    We study a minimal model for a relaxor ferroelectric including dipolar interactions and short-range harmonic and anharmonic forces for the critical modes as in the theory of pure ferroelectrics together with quenched disorder coupled linearly to the critical modes. We present the simplest approximate solution of the model necessary to obtain the principal features of the correlation functions. Specifically, we calculate and compare the structure factor measured by neutron scattering in different characteristic regimes of temperature in the relaxor Pb (Mg1 /3Nb2 /3)O3 .

  8. Relaxor Ferroelectric Behavior from Strong Physical Pinning in a Poly(vinylidene fluoride-co-trifluoroethylene-co-chlorotrifluoroethylene) Random Terpolymer

    NASA Astrophysics Data System (ADS)

    Zhu, Lei; Yang, Lianyun; Tyburski, Brady; Domingues Dos Santos, Fabrice

    2015-03-01

    Although narrow single hysteresis loop (SHL) is observed for electron beam (e-beam) irradiated poly(vinylidene fluoride-co-trifluoroethylene) [P(VDF-TrFE)] random copolymers owing to strong chemical pinning in isomorphic (or defect-modified) crystals, it has not been achieved for P(VDF-TrFE)-based random terpolymers, such as P(VDF-TrFE-CFE) (CFE is 1,1-chlorofluoroethylene), which only exhibits double hysteresis loops (DHLs). This is attributed to the weak physical pinning of CFE units in isomorphic crystals. In this work, the comonomer CFE in the terpolymer was replaced by the larger chlorotrifluoroethylene (CTFE). Intriguingly, narrow SHLs were exclusively observed for the P(VDF-TrFE-CTFE) terpolymer above room temperature. This was attributed to the stronger physical pinning force of the larger CTFE, which has a smaller dipole moment (only 0.64 Debye). This result provides us further insight into the structure and behavior of relaxor ferroelectric polymers, which can help to design and develop new ferroelectric polymers with more desirable properties and enhanced performance. This work is supported by National Science Foundation (DMR-0907580 and DMR-1402733).

  9. Aging and Barkhausen noise in the relaxor ferroelectrics

    Microsoft Academic Search

    Lambert Key Chao

    2006-01-01

    Relaxor ferroelectrics are disordered crystalline materials whose polar order is limited to mesoscopic-scaled nanodomains. There is no ferroelectric phase transition, but a faster than Arrhenius cooperative freezing into a glassy relaxor regime instead. It is not understood how the random fields and random interactions present in these dielectrics inhibit the formation of long-range ferroelectric order. This thesis presents two types

  10. Field-induced percolation of polar nanoregions in relaxor ferroelectrics.

    PubMed

    Prosandeev, S; Wang, Dawei; Akbarzadeh, A R; Dkhil, B; Bellaiche, L

    2013-05-17

    A first-principles-based effective Hamiltonian is used to investigate low-temperature properties of Ba(Zr,Ti)O(3) relaxor ferroelectrics under an increasing dc electric field. This system progressively develops an electric polarization that is highly nonlinear with the dc field. This development leads to a maximum of the static dielectric response at a critical field, E(th), and involves four different field regimes. Each of these regimes is associated with its own behavior of polar nanoregions, such as shrinking, flipping, and elongation of dipoles or change in morphology. The clusters propagating inside the whole sample, with dipoles being parallel to the field direction, begin to form at precisely the E(th) critical field. Such a result, and further analysis we perform, therefore, reveal that field-induced percolation of polar nanoregions is the driving mechanism for the transition from the relaxor to ferroelectric state. PMID:25167451

  11. Aging and Barkhausen noise in the relaxor ferroelectrics

    NASA Astrophysics Data System (ADS)

    Chao, Lambert Key

    Relaxor ferroelectrics are disordered crystalline materials whose polar order is limited to mesoscopic-scaled nanodomains. There is no ferroelectric phase transition, but a faster than Arrhenius cooperative freezing into a glassy relaxor regime instead. It is not understood how the random fields and random interactions present in these dielectrics inhibit the formation of long-range ferroelectric order. This thesis presents two types of experiments aimed at shedding light on this issue: aging and Barkhausen noise. Aging shows low-temperature regimes with spin-glass-like behavior in relaxors with cubic perovskite crystalline structure that are not present in those with uniaxial tungsten-bronze crystalline structure. In particular, the cubic relaxor PMN/PT (90/10) [(PbMn1/3Nb2/3O3)1- x(PbTiO3)x, x = 0.1] shows aging that directly parallels that in re-entrant spin-glasses, with "hole-like" aging at low-temperature, where the uniaxial relaxor SBN:La (60/40) [Srx-yLayBa1- xNb2O6, x = 0.6, y = 0.01] shows cumulative, not "hole-like" aging. The Barkhausen experiments measure the noise from the abrupt reorientation of polar clusters driven by an ac field, giving a measure of a typical dynamic dipole step size in PMN/PT (90/10) of about 100 nanodomains in the paraelectric regime, which then abruptly freezes out on cooling into the relaxor regime. This suggests an abrupt growth of barriers associated with the dipoles. The presence of complicated spin-glass-like aging, requiring cooperativity between many aging units, combined with the relative insensitivity of aging effects to small field perturbations suggest that units much smaller than nanodomains are responsible for the aging. This points to a picture of the cubic relaxors where polar regions are coupled to canted moments orthogonal to the mean mid-scale polarization (Egami, 1999; Dkhil et al., 2001) which provide the glassy freezing, much like a re-entrant xy spin-glass. These canted moments are the unit cell analogs to tweed domain-patterning seen in PMN/PT compositions with large ferroelectric doping (Viehland et al., 1995; Xunhu et al., 1994). We note the relevance of a theory mapping the pre-martensitic tweed Hamiltonian onto a spin-glass Hamiltonian (Kartha et al., 1991; Sethna et al., 1992). We also present evidence of possible discrete polarization/depolarization steps in the pyroelectric current of SBN:La (60/40).

  12. Development of “fragility” in relaxor ferroelectrics

    SciTech Connect

    Wang, Yi-zhen, E-mail: wangyizhen80@gmail.com [College of Physics and Electronic Engineering, Hainan Normal University, Haikou 571158 (China); Bioengineering Program and Mechanical Engineering and Mechanics Department, Lehigh University, 19 Memorial Drive West, Bethlehem, Pennsylvania 18015 (United States); State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275 (China); Chen, Lan; Xiong, Xiao-min; Zhang, Jin-xiu [State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275 (China); Wang, Hai-yan [State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275 (China); Guangzhou Institute of Measurement and Testing Technology, Guangzhou 510663 (China); Frank Zhang, X. [Bioengineering Program and Mechanical Engineering and Mechanics Department, Lehigh University, 19 Memorial Drive West, Bethlehem, Pennsylvania 18015 (United States); Fu, Jun [College of Physics and Electronic Engineering, Hainan Normal University, Haikou 571158 (China)

    2014-02-07

    Relaxor ferroelectrics (RFs), a special class of the disordered crystals or ceramics, exhibit a pronounced slowdown of their dynamics upon cooling as glass-forming liquids, called the “Super-Arrhenius (SA)” relaxation. Despite great progress in glass-forming liquids, the “fragility” property of the SA relaxation in RFs remains unclear so far. By measuring the temperature-dependent dielectric relaxation in the typical relaxor Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}-x%PbTiO{sub 3} (PMN???x%PT) with 0???x???20.0, we in-depth study the “fragility” properties of the SA relaxation in PMN???x%PT. Such fascinating issues as the mechanism of the “fragility” at an atomic scale, the roles of the systematic configurational entropy change and interaction among relaxing units (RUs, including polar nanoregions and free dipoles) and the relation between “fragility” and ferroelectric order are investigated. Our results show that both the “fragility” of the temperature-dependent SA relaxation and ferroelectric order in the PMN???x%PT systems investigated arise thermodynamically from the configurational-entropy loss due to the attractive interaction among RUs, and develops as a power law, possibly diverging at the finite critical temperature T{sub c}. A reasonable physical scenario, based on our “configurational-entropy-loss” theory and Nowick's “stress-induced-ordering” theory, was proposed.

  13. Local structure in perovskite relaxor ferroelectrics: high-resolution 93

    E-print Network

    Vold, Robert

    Local structure in perovskite relaxor ferroelectrics: high-resolution 93 Nb 3QMAS NMR Donghua H in capacitors, sensors, actuators, and transduc- ers [1,2]. Most relaxors have ABO3 pseudo-perovskite structure to paraelectric phase transition [4]. In PSN-type perovskites, for example PbSc1=2Ta1=2O3 (PST), the 1:1 long

  14. Anisotropic nonlinear dielectric response of relaxor ferroelectrics

    NASA Astrophysics Data System (ADS)

    Pirc, R.; Blinc, R.; Vikhnin, V. S.

    2006-08-01

    The anisotropy of the nonlinear static dielectric response of inorganic relaxor ferroelectrics of lead magnesium niobate (PMN) type is studied in the framework of the spherical random bond-random field model. Assuming that the shape of a polar nanoregion (PNR) and thus its dipole moment is modified by the action of homogeneous lattice strains, the anisotropic part of the interaction between the PNRs is derived. This interaction is bilinear in the electric field as well as in the order parameter field components, and gives rise to an effective field-dependent interaction strength, which depends both on the magnitude and the direction of the electric field. In addition to the isotropic intrinsic nonlinearity of the system studied earlier, we thus obtain an anisotropic part of the nonlinear response. By comparing the results with the experimental data of Tagantsev and Glazounov [Appl. Phys. Lett. 74, 1910 (1999)] for PMN we calculate the temperature dependence of the anharmonicity coefficients in the effective free energy of the system.

  15. Anisotropic Local Correlations and Dynamics in a Relaxor Ferroelectric

    NASA Astrophysics Data System (ADS)

    Takenaka, Hiroyuki; Grinberg, Ilya; Rappe, Andrew M.

    2013-04-01

    Relaxor ferroelectrics have been a focus of intense attention due to their anomalous properties, and understanding the structure and dynamics of relaxors has been one of the long-standing challenges in solid-state physics. We investigate the local structure and dynamics in 75%PbMg1/3Nb2/3O3-25%PbTiO3 using molecular dynamics simulations and the dynamic pair distribution function technique. We show that relaxor transitions can be described by local order parameters. The relaxor phase is characterized by the presence of highly anisotropic correlations between the local cation displacements that resemble the hydrogen bond network in water. This contradicts the current model of polar nanoregion inside a nonpolar matrix. We therefore suggest a new model of a homogeneous random network of anisotropically coupled dipoles.

  16. High frequency dielectric spectroscopy of relaxor ferroelectrics and related materials

    Microsoft Academic Search

    V. Bovtun; J. Petzelt; S. Kamba; K. Porokhonskyy; A. Pashkin; S. Veljko; P. Samoukhina; Y. Yakimenko

    2004-01-01

    Relaxor and doped incipient ferroelectrics represent the partially disordered solids, where the main lattice periodicity is preserved and only some of the sublattices exhibit disorder. Dielectric response of these polar materials is defined by both crystal lattice dynamics and relaxational processes in a wide frequency range below the phonon frequencies. High frequency part of the response is very important for

  17. Computational Study of Local Structure and Dynamics in a Relaxor Ferroelectric

    NASA Astrophysics Data System (ADS)

    Takenaka, Hiroyuki

    2014-03-01

    Relaxor ferroelectrics exhibit a stronger piezoelectric effect, diffuse phase transitions with high permittivity, and unique dielectric response with strong frequency dispersion which are exploited for technological applications and give rise to scientific interest. The diffuse phase transitions have been explained by widely accepted model of polar nanoregions inside a non-polar matrix. Recent experimental and theoretical results, however, suggest requirements of alternate interpretations of the origin of the relaxor behavior. Macroscopic elucidations of structure and dynamics in relaxors are still one of challenging topics in solid-state physics. We analyzed local structure and dynamics with dynamic pair distribution function and diffuse scattering techniques for 0.75PbMg1/3Nb2/3O3-0.25PbTiO3, a prototypical relaxor, performing molecular dynamics simulations. Our analysis showed phase transition temperatures in good agreement with experimental values. From inspections of in-phase motion correlations for Pb pairs, we found analogy between the phase transition from the paraelectric phase to the relaxor phase in the relaxor and the behavior of the couplings from high temperature to room temperature in water. We, therefore, propose alternate model. This work was supported by the Department of Energy under grant DE-FG02-07ER46431.

  18. Recent progress in relaxor ferroelectrics with perovskite structure

    Microsoft Academic Search

    A. A. Bokov; Z.-G. Ye

    2006-01-01

    Relaxor ferroelectrics were discovered almost 50 years ago among the complex oxides with perovskite structure. In recent years\\u000a this field of research has experienced a revival of interest. In this paper we review the progress achieved. We consider the\\u000a crystal structure including quenched compositional disorder and polar nanoregions (PNR), the phase transitions including compositional\\u000a order-disorder transition, transition to nonergodic (probably

  19. Mesoscopic harmonic mapping of electromechanical response in a relaxor ferroelectric

    NASA Astrophysics Data System (ADS)

    Vasudevan, Rama K.; Zhang, Shujun; Ding, Jilai; Okatan, M. Baris; Jesse, Stephen; Kalinin, Sergei V.; Bassiri-Gharb, Nazanin

    2015-06-01

    Relaxor-ferroelectrics are renowned for very large electrostrictive response, enabling applications in transducers, actuators, and energy harvesters. However, insight into the dissimilar contributions (polarization rotation, wall motion) to the electromechanical response from electrostrictive strain, and separation of such contributions from linear piezoelectric response are largely ignored at the mesoscale. Here, we employ a band-excitation piezoresponse force microscopy (BE-PFM) technique to explore the first and second harmonics of the piezoelectric response in prototypical relaxor-ferroelectric 0.72Pb(Mg1/3Nb2/3)O3-0.28PbTiO3 (PMN-0.28PT) single crystals. Third order polynomial fitting of the second harmonic reveals considerable correlation between the cubic coefficient map and the first harmonic piezoresponse amplitude. These results are interpreted under a modified Rayleigh framework, as evidence for domain wall contributions to enhanced electromechanical response. These studies highlight the contribution of domain wall motion in the electromechanical response of relaxor ferroelectrics, and further show the utility of harmonic BE-PFM measurements in spatially mapping the mesoscopic variability inherent in disordered systems.

  20. Mesoscopic cell structure of relaxor ferroelectrics at morphotropic phase boundary

    NASA Astrophysics Data System (ADS)

    Ahn, Sang-Jin; Kim, Jong-Jean

    2003-03-01

    Mesoscopic cell structure of relaxor ferroelectrics at morphotropic phase boundary Sang-Jin Ahn and Jong-Jean Kim Physics Department, KAIST, Taejon 305-701, Korea Relaxor-based ferroelectrics such as PZN-xPT and PMN-xPT have drawn a great attention due to an observation of a huge piezoelectric coefficient and an ultra high strain level. Although the first principle calculations on the basis of a single perovskite unit cell structure could explain much of the experimental observations, recent observations of a complex mesoscopic ordering and a heterogeneous domain structure suggest a composite cell of many perovskite units as a basic building block. Raman scattering spectra and observed stoichiometry of PZN-xPT and PMN-xPT allow for only a random pile-up structure of the composite block cells. Our composite block cell needs 27 perovskite unit cells to satisfy the morphotropic phase boundary conditions of structural and compositional variations. Using this mesoscopic block cell model we calculate for allowed mixing concentrations x at morphotropic phase boundaries of relaxor ferroelectrics, which agree with observed values.

  1. The Effect of Nearest Neighbor [Pb-O] Divacancy Pairs on the Ferroelectric-Relaxor

    E-print Network

    Burton, Benjamin P.

    The Effect of Nearest Neighbor [Pb-O] Divacancy Pairs on the Ferroelectric-Relaxor Transition Ceramics Division, Materials Science and Engineering Laboratory, National Institute of Standards diagram: a ferroelectric ground-state phase at low X[Pb-O] (P); that transforms to a relaxor paraelectric

  2. Properties of epitaxial films made of relaxor ferroelectrics.

    PubMed

    Prosandeev, S; Wang, Dawei; Bellaiche, L

    2013-12-13

    Finite-temperature properties of epitaxial films made of Ba(Zr,Ti)O3 relaxor ferroelectrics are determined as a function of misfit strain, via the use of a first-principles-based effective Hamiltonian. These films are macroscopically paraelectric at any temperature, for any strain ranging between ?-3% and ?+3%. However, original temperature-versus-misfit strain phase diagrams are obtained for the Burns temperature (Tb) and for the critical temperatures (Tm,z and Tm,IP) at which the out-of-plane and in-plane dielectric response peak, respectively, which allow the identification of three different regions. These latter differ from their evolution of Tb, Tm,z, and/or Tm,IP with strain, which are the fingerprints of a remarkable strain-induced microscopic change: each of these regions is associated with its own characteristic behavior of polar nanoregions at low temperature, such as strain-induced rotation or strain-driven elongation of their dipoles or even increase in the average size of the polar nanoregions when the strength of the strain grows. PMID:24483699

  3. Influencing dielectric properties of relaxor polymer system by blending vinylidene fluoride-trifluoroethylene-based terpolymer with a ferroelectric copolymer

    NASA Astrophysics Data System (ADS)

    Casar, G.; Li, X.; Zhang, Q. M.; Bobnar, V.

    2014-03-01

    We report the influence of blending the poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) terpolymer [P(VDF-TrFE-CFE), a member of the relaxor polymer family that exhibits fast response speeds, giant electrostriction, high electric energy density, and large electrocaloric effect] with the ferroelectric poly(vinylidene fluoride-trifluoroethylene) copolymer [P(VDF-TrFE)] on its dielectric response. Although both components form separate crystalline phases, at low copolymer content, the P(VDF-TrFE-CFE)/P(VDF-TrFE) blends entirely exhibit a relaxorlike linear dielectric response, since the interfacial couplings to the bulky defects in the terpolymer convert the normal ferroelectric copolymer into a relaxor. On the other hand, the linear and particularly nonlinear dielectric experiments, i.e., temperature dependences of the second and the third harmonic dielectric response, clearly evidence that in blends with 20-50 wt. % of P(VDF-TrFE), the ferroelectric and relaxor states coexist. The nonlinear dielectric response further reveals the onset of ferroelectric behavior also in blends with low copolymer amount, due to a high VDF content in the terpolymer, which increases the ferroelectric interactions: While in relaxor polymers with lower VDF content, the third order nonlinear dielectric constant, in accordance with the theoretical predictions, exhibits solely positive values, here it changes sign even in the pure P(VDF-TrFE-CFE).

  4. Comparison of directly and indirectly measured electrocaloric effect in relaxor ferroelectric polymers

    NASA Astrophysics Data System (ADS)

    Lu, S. G.; Roži?, B.; Zhang, Q. M.; Kutnjak, Z.; Pirc, R.; Lin, Minren; Li, Xinyu; Gorny, Lee

    2010-11-01

    We report the directly measured electrocaloric effect (ECE) (the adiabatic temperature change ?T) of relaxor ferroelectric poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) terpolymer and its blend with poly(vinylidene fluoride-chlorotrifluoroethylene). The results show that the directly measured ?T in the relaxor terpolymer is much larger than that deduced from Maxwell relation and that the relaxor terpolymer possesses a giant ECE at room temperature. The large difference between the directly measured ?T and that deduced indicates that the Maxwell relation, which is derived for ergodic systems, is not suitable for deducing ECE in the relaxor ferroelectric polymers, which are nonergodic (polar-glass) material systems.

  5. Electric-fieldtemperature phase diagram of the relaxor ferroelectric lanthanum-modified lead zirconate titanate

    E-print Network

    Bobnar, Vid

    ferroelectrics. S0163-1829 99 00233-7 I. INTRODUCTION Lanthanum-modified lead zirconate titanate ceramics Pb1 x than EC 5 kV/cm a long-range ferroelectric order is established in 9/65/35 PLZT ceramics. In particularElectric-field­temperature phase diagram of the relaxor ferroelectric lanthanum-modified lead

  6. Coexistence of ferroelectric and relaxor states in Ba2PrxNd1-xFeNb4O15.

    PubMed

    Kinka, Martynas; Josse, Michael; Castel, Elias; Bagdzevicius, Sarunas; Samulionis, Vytautas; Grigalaitis, Robertas; Banys, Juras; Maglione, Mario

    2012-09-01

    We have investigated the dielectric response of Ba(2)Pr(x)Nd(1-x)FeNb(4)O(15) ceramics (x = 0, 0.2, 0.5, 0.6, 0.8, 1) in the frequency range from 20 Hz to 1 GHz. The obtained results confirmed the continuous transformation from the ferroelectric behavior of Ba2NdFeNb4O15 to the pure relaxor response of Ba(2)PrFeNb(4)O(15) with increasing x. For intermediate x values, coexisting ferroelectric transition and relaxor dielectric signatures were observed, corresponding to two different phenomena in the framework of these materials. Increasing the amount of Pr decreases the ferroelectric phase transition temperatures in these ceramics; a large cooling¿heating hysteresis exceeding 50K was also observed. PMID:23007754

  7. Dispersion and distribution of optical index of refraction in ferroelectric relaxor crystal

    NASA Astrophysics Data System (ADS)

    Li, Chunlai

    This thesis deals with the optical properties of relaxor ferroelectrics with nano/micro polar regions, including their optical frequency dispersion near phase transition, thermo-optical properties, and transmission spectrum analysis. The essential objectives of this thesis work are to deepen the understanding on diffuse phase transition of relaxor ferroelectrics and to obtain practical data for potential optical application from technically important ferroelectrics crystals PBN and PZN-PT. Temperature dependent birefringence and optical refractive indices of PBN (Pb1-xBaxNb2O6) crystal (1-x=0.57) were measured in several optical wavelengths (lambda= 694nm, 633nm, 535nm, and 450nm) to understand the optical frequency dependency of ferroelectric phase transitions in relaxor ferroelectric crystals of tungsten bronze structure. Local polarization is verified to be dynamically activated by thermal process and probed effectively by suitable wavelength of light. An optical isotropic point, as a function of temperature and light frequency, is reported at which the crystal's standing birefringence is fully compensated by polarization. A modified single oscillator model is used to calculate the index of refraction in the ferroelectric phase. The deviation temperature from the single oscillator model is reported to be significantly marking the crossover from macroscopic to microscopic polarization. A new parameter, optical Curie temperature region, defined by the temperature difference between the well known Burns temperature and the deviation temperature (from the single oscillator model for index of refraction) is explored for its significance in depolarization behavior of the micro- to nano-polar regions of the ferroelectric relaxor. Temperature dependent optical indices of refraction of PZN-0.12PT (1-x)PbZn 1/3Nb2/3O3-xPbTiO3, x=0.12, were also studied with emphasis on poling effect. The refractive index n3 decreases as a result of [001] poling. Temperature dependent effective energy of dispersion oscillator E0 and dispersion energy Ed were calculated using single oscillator model and found that E0 and Ed increased by 32% and 60% after [001] poling, respectively. Birefringence of poled PZN-0.12PT also was measured with several frequencies and varying temperature. The polarization derived from refractive index and birefringence were consistent with each other. The remnant polarization was increased by approximately 30% as a result of [001] poling. Transmission spectrum of PZN-0.12PT was measured from near UV to IR for both poled sample and unpoled sample. Transmission was improved significantly after poling. By analyzing the transmission spectrum in the visible range, optical band gap and lattice phonon were determined. The existence of hydrogen in PZN-0.12PT single crystal grown by flux method was postulated based on evidence obtained by FTIR. For accurate and fast birefringence measurement, which is of fundamental importance to device design, quality control, and various sensing functions, a two-dimensional birefringence profiling and analysis system was designed and implemented successfully. Jones matrices of two and three 90° domains are derived and conclude that odd number of stacked 90° domains can be treated as a single 90° domain while even number of stacked 90° domains can be treated as two 90° domains. By rotating analyzer method a test experiment using voltage controllable liquid crystal as sample is demonstrated.

  8. High-temperature dielectric response of ferroelectric relaxors.

    PubMed

    Bobnar, Vid; Erste, Andreja; Gradisar, Urska; Filipic, Cene; Levstik, Adrijan; Kutnjak, Zdravko

    2011-11-01

    It has long been considered that polar nanoregions in relaxors form at Burns temperature T(d) ? 600K. High-temperature dielectric investigations of Pb(Mg(1/3)Nb(2/3)) O(3) (PMN) single crystal, PMN-PbTiO(3) ceramics, and (Pb,La) (Zr,Ti)O(3) ceramics reveal, however, that dielectric dispersion, detected around 600K, is due to the Maxwell-Wagner-type contributions of surface layers. The intrinsic response was analyzed in terms of the universal scaling, taking into account the asymptotic and the correction-to-scaling behavior, and the results imply much higher T(d) or formation of polar nanoregions in a broad temperature range. High values of the dielectric constant indicate, however, that polar order already exists at the highest measured temperatures of 800K. The obtained critical exponents indicate critical behavior associated with universality classes typically found in spin glasses. PMID:22083759

  9. First-principles-based effective Hamiltonian simulations of bulks and films made of lead-free Ba(Zr,Ti)O3 relaxor ferroelectrics

    NASA Astrophysics Data System (ADS)

    Prosandeev, Sergey; Wang, Dawei; Akbarzdeh, A. R.; Bellaiche, L.

    2015-06-01

    A review of the recent development and application of a first-principles-derived effective Hamiltonian technique to the study of lead-free Ba(Zr,Ti)O3 (BZT) relaxor ferroelectrics is provided. In addition to the computation and analysis of macroscopic properties (such as different types of dielectric responses and electric polarization) and their connections to previous published works, particular emphasis is given to microscopic insights arising from this atomistic technique. These include (i) the numerically-found determination of the physical origin of the relaxor behavior in BZT; and (ii) the prediction of polar nanoregions and the evolution of their morphology as a response to temperature, electric fields and epitaxial misfit strain. Other striking phenomena that were predicted in BZT compounds, such as Fano resonance and field-driven percolation, are also documented and discussed. Finally, a brief perspective of possible remaining computational studies to be conducted in relaxor ferroelectrics, in order to further understand them, is attempted.

  10. Ferroelectric to relaxor crossover and dielectric phase diagram in the BaTiO3-BaSnO3 system

    NASA Astrophysics Data System (ADS)

    Lei, C.; Bokov, A. A.; Ye, Z.-G.

    2007-04-01

    The (1-x)BaTiO3-xBaSnO3 (0?x?0.30) perovskite solid solution ceramics were prepared by solid state reaction and studied by dielectric spectroscopy. The complex dielectric permittivity was measured as a function of frequency (0.1Hz-100kHz) in the temperature (T) range of 123-573K. The transition from the high-temperature paraelectric state where the dielectric constant obeys the Curie-Weiss law to the ergodic cluster state is found to occur at the same temperature of 485K in all the compositions of x ?0.04 and at lower temperatures in those with a smaller x. For 0?x?xc=0.19, the temperature of the dielectric peak Tm, corresponding to the diffuse transition from the ergodic polar cluster state to the ferroelectric state, decreases with increasing x and does not depend on frequency. The diffuseness of the peak gradually increases. For x >xc, the permittivity exhibits relaxor behavior with the frequency-dependent Tm satisfying the Vogel-Fulcher law. The temperature variation of the permittivity on the high-temperature slope of the peak (T>Tm) is characterized by the characteristic Lorenz-type quadratic law for relaxors, with the diffuseness increasing with the increase of x. The mechanisms of the dielectric response in different parts of the phase diagram are discussed. In particular, the crossover from diffuse ferroelectric phase transition to relaxor ferroelectric behavior is attributed to the appearance at x >xc of the additional dielectric contribution arising from the flipping of the local polarization of the polar clusters. The temperature-composition phase diagram of the Ba(Ti1-xSnx)O3 system has been established, which delimits the paraelectric, ergodic polar cluster, nonergodic ferroelectric, and relaxor phases (states) and indicates the crossover from ferroelectric to relaxor behavior at x =xc.

  11. Development of phonon-polarization THz spectroscopy, and the investigation of relaxor ferroelectrics

    E-print Network

    Paxton, Benjamin John

    2006-01-01

    This thesis develops phonon-polariton based THz spectroscopy and uses this technique to make the first THz frequency dielectric measurements of a relaxor ferroelectric crystal, in particular KTao0.982Nb0.018O3 (KTN 1.8). ...

  12. Lattice-based Monte Carlo simulations of the electrocaloric effect in ferroelectrics and relaxor ferroelectrics

    NASA Astrophysics Data System (ADS)

    Ma, Yang-Bin; Albe, Karsten; Xu, Bai-Xiang

    2015-05-01

    Canonical and microcanonical Monte Carlo simulations are carried out to study the electrocaloric effect (ECE) in ferroelectrics and relaxor ferroelectrics (RFEs) by direct computation of field-induced temperature variations at the ferroelectric-to-paraelectric phase transition and the nonergodic-to-ergodic state transformation. A lattice-based Hamiltonian is introduced, which includes a thermal energy, a Landau-type term, a dipole-dipole interaction energy, a gradient term representing the domain-wall energy, and an electrostatic energy contribution describing the coupling to external and random fields. The model is first parametrized and studied for the case of BaTiO3. Then, the ECE in RFEs is investigated, with particular focus on the influence of random fields and domain-wall energies. If the strength or the density of the random fields increases, the ECE peak shifts to a lower temperature but the temperature variation is reduced. On the contrary, if the domain-wall energy increases, the peak shifts to a higher temperature and the ECE becomes stronger. In RFEs, the ECE is maximum at the freezing temperature where the nonergodic-to-ergodic transition takes place. Our results imply that the presence of random fields reduces the entropy variation in an ECE cycle by pinning local polarization.

  13. Observation of an unusual optical switching effect in relaxor ferroelectrics Pb(Mg1/3Nb2/3)O3-Pb(Zr0.53,Ti0.47)O3 transparent ceramics

    NASA Astrophysics Data System (ADS)

    Zhao, Wei; Ruan, Wei; Zeng, Jiangtao; Huang, Lizhu; Zhao, Kunyu; Zheng, Liaoying; Zeng, Huarong; Zhou, Yibo; Yang, Heji; Ruan, Xuezheng; Li, Guorong

    2014-02-01

    We present an unusual optical switching effect in relaxor ferroelectrics Pb(Mg1/3Nb2/3)O3-Pb(Zr0.53,Ti0.47)O3 transparent ceramics under strong AC electric fields, which is accompanied by a peculiar dielectric response rarely reported previously and attributed to the disruption of the ferroelectric domain structure by the strong AC field. The results provide further understanding on the domain behaviors under electric fields of the relaxor ferroelectrics and the potential for advancing electro-optic applications.

  14. Microstructure and strength modification of relaxor ferroelectric ceramics through microwave sintering for multilayer capacitors

    Microsoft Academic Search

    Zhipeng Xie; Yong Huang; Zhilun Gui; Jinlong Yang; Longtu Li

    1999-01-01

    Relaxor ferroelectric ceramics with the composition ofxPb(Mg1\\/3Nb2\\/3)O3-yPb(Zn1\\/3Nb2\\/3)O3-zPbTiO3 was fast sintered in a 2.45 GHz microwave system. Microwave-sintered samples illustrate more rapid densification and much\\u000a smaller grain size microstructure than conventional sintered samples. Also the microwave processing significantly increases\\u000a the dielectric strength and flexural strength of the relaxor so that its strength becomes comparable with modified BaTiO3, and could obtain comparable

  15. Order parameter and scaling behavior in BaZr{sub x}Ti{sub 1?x}O{sub 3} (0.3 < x < 0.6) relaxor ferroelectrics

    SciTech Connect

    Usman, Muhammad; Mumtaz, Arif, E-mail: arif@qau.edu.pk; Raoof, Sobia; Hasanain, S. K. [Department of Physics, Quaid-i-Azam University, Islamabad 45320 (Pakistan)] [Department of Physics, Quaid-i-Azam University, Islamabad 45320 (Pakistan)

    2013-12-23

    We report the relaxor behavior of the zirconium doped barium titanate BaZr{sub x}Ti{sub 1?x}O{sub 3} solid solutions and discuss the temperature, frequency, and concentration dependence in terms of correlations among the polar nanoregions. The relaxor behavior is analyzed within the mean field theory by estimating the Edward-Anderson order parameter q{sub EA}. Additionally, we find that q{sub EA} calculated for the different concentrations obeys a scaling behavior q{sub EA}=1?(T/T{sub m}){sup n}, where T{sub m} are the respective dielectric maxima temperatures and n?=?2.0?±?0.1. The frequency dependence of the q{sub EA} also shows results consistent with the above mentioned picture.

  16. High performance ferroelectric relaxor-PbTiO3 single crystals: Status and perspective

    NASA Astrophysics Data System (ADS)

    Zhang, Shujun; Li, Fei

    2012-02-01

    Ferroelectrics are essential components in a wide range of applications, including ultrasonic transducers, sensors, and actuators. In the single crystal form, relaxor-PbTiO3 (PT) piezoelectric materials have been extensively studied due to their ultrahigh piezoelectric and electromechanical properties. In this article, a perspective and future development of relaxor-PT crystals are given. Initially, various techniques for the growth of relaxor-PT crystals are reviewed, with crystals up to 100 mm in diameter and 200 mm in length being readily achievable using the Bridgman technique. Second, the characterizations of dielectric and electromechanical properties are surveyed. Boundary conditions, including temperature, electric field, and stress, are discussed in relation to device limitations. Third, the physical origins of the high piezoelectric properties and unique loss characteristics in relaxor-PT crystals are discussed with respect to their crystal structure, phase, engineered domain configuration, macrosymmetry, and domain size. Finally, relaxor-PT single crystals are reviewed with respect to specific applications and contrasted to conventional piezoelectric ceramics.

  17. Lead magnesium niobate relaxor ferroelectric ceramics of low-firing for multilayer capacitors

    Microsoft Academic Search

    Zhilun Gui; Yiushun Liu; Hongfei Sun

    1988-01-01

    Lead-magnesium-niobate relaxor ferroelectric ceramics with a high dielectric constant and low sintering temperature for multilayer capacitors have been studied. PMN-PT-PCW and PMN-PT+excess PbO+excess MgO with normal, chemically pure raw materials processed by the direct formation of oxides (mixed-oxides procedure) were sintered at 860-960°C. Values of ?max from 13000 to 18500 (at 1 kHz) and good aging characteristics were obtained. By

  18. Polar nanodomains and local ferroelectric phenomena in relaxor lead lanthanum zirconate titanate ceramics

    SciTech Connect

    Shvartsman, V.V.; Kholkin, A.L.; Orlova, A.; Kiselev, D.; Bogomolov, A.A.; Sternberg, A. [Department of Ceramics and Glass Engineering and Center for Research in Ceramic and Composite Materials (CICECO), University of Aveiro, 3810-193 Aveiro (Portugal); Department of Physics, Tver State University, 170000 Tver (Russian Federation); Institute of Solid State Physics, University of Latvia, LV-1063 Riga (Latvia)

    2005-05-16

    Transparent Pb{sub 0.9125}La{sub 0.0975}(Zr{sub 0.65}Ti{sub 0.35}){sub 0.976}O{sub 3} ceramics (conventionally abbreviated as PLZT 9.75/65/35) is a typical relaxor characterized by the absence of the ferroelectric order at the macroscopic scale. In this letter, we report on the observation of complex polar structures on the surface of this material via piezoresponse force microscopy (PFM). The irregular polarization patterns are associated with the formation of a glassy state, where random electric fields destroy the long-range ferroelectric order. The measure of the disorder, the correlation length of {approx}50 nm, was directly deduced from the PFM images. Local poling of relaxor ceramics resulted in the formation of a stable micron-size domain that could be continuously switched under varying dc bias (local relaxor-ferroelectric phase transition). Fractal analysis was applied to analyze the origin of local order in PLZT.

  19. Effect of grain size on the electrical properties of (Ba,Ca)(Zr,Ti)O3 relaxor ferroelectric ceramics

    NASA Astrophysics Data System (ADS)

    Tang, Xin-Gui; Chan, Helen Lai-Wah

    2005-02-01

    (Ba0.90Ca0.10)(Zr0.25Ti0.75)O3 (BCZT) relaxor ferroelectric ceramics with grain sizes of 0.85, 2.5, 15, and 30?m were prepared from powders synthesized using a sol-gel process. The effects of grain size and dc field on the dielectric properties and tunabilities of BCZT ceramics were investigated. As the grain size decreased, the maximum dielectric constant decreased and the transition temperature increased. The BCZT ceramics with various grain sizes showed a typical relaxor ferroelectric behavior. The dielectric relaxation rate follows the Vogel-Fulcher relation. The dielectric constant is greatly suppressed and the low loss is obtained under a dc electric field. At room temperature (300K) and 20kV/cm, the tunabilities and figures of merit are 42% and 62, 51% and 98, 56% and 193, and 51% and 182, respectively, for the BCZT ceramics with grain sizes of 0.85, 2.5, 15, and 30?m.

  20. Fracture of ferroelectric and relaxor electro-ceramics: influence of electric field 1 1 Work begun during a post doctoral appointment at the University of California, Santa Barbara

    Microsoft Academic Search

    Christopher S. Lynch

    1998-01-01

    Crack growth is studied in a ferroelectric and a relaxor composition of lead lanthanum zirconate titanate (PLZT) ceramic using Vicker’s indentations with electric field. The polarized ferroelectric composition displays excess crack growth perpendicular to the polarization direction. This excess crack growth is increased by an electric field in the polarization direction. The relaxor composition does not display this excess crack

  1. Dielectric properties and relaxor behavior of rare-earth (La, Sm, Eu, Dy, Y) substituted barium zirconium titanate ceramics

    SciTech Connect

    Chou Xiujian; Zhai Jiwei; Jiang Haitao; Yao Xi [Functional Materials Research Laboratory, Tongji University, Siping Road 1239, Shanghai 200092 (China)

    2007-10-15

    Based on the Ti-vacancy defect compensation model (Ba{sub 1-x}Ln{sub x})Zr{sub 0.2}Ti{sub 0.8-x/4}O{sub 3} (Ln=La,Sm,Eu,Dy,Y) ceramics have been fabricated via the conventional solid-state reaction method. The microstructures, dielectric properties, and ferroelectric relaxor behavior of (Ba{sub 1-x}Ln{sub x})Zr{sub 0.2}Ti{sub 0.8-x/4}O{sub 3} ceramics have been investigated. The results indicate that rare-earth ions with various ionic radii enter the unit cell to substitute for A-site Ba{sup 2+} ions and inhibit the grain growth. The typical ferroelectric relaxor behavior is induced due to the rare-earth ions substitution. The diffuseness of the phase transition and the degree of ferroelectric relaxor behavior are enhanced, the T{sub C} is remarkably shifted to lower temperature, and the tunability is suppressed with the increase of x value and substituted ionic radius for (Ba{sub 1-x}Ln{sub x})Zr{sub 0.2}Ti{sub 0.8-x/4}O{sub 3} (x=0.005-0.04, Ln=La,Sm,Eu,Dy,Y) ceramics. Tunable ferroelectric materials with moderate dielectric constant and low dielectric loss can be obtained by manipulating the doping amount of suitable rare-earth ions.

  2. Direct evidence of correlations between relaxor behavior and polar nano-regions in relaxor ferroelectrics: A case study of lead-free piezoelectrics Na0.5Bi0.5TiO3-x%BaTiO3

    NASA Astrophysics Data System (ADS)

    Ge, Wenwei; Luo, Chengtao; Devreugd, Christopher P.; Zhang, Qinhui; Ren, Yang; Li, Jiefang; Luo, Haosu; Viehland, D.

    2013-12-01

    Diffuse scattering and relaxor behavior in Na0.5Bi0.5TiO3 (NBT) and NBT-5.6 at. %BaTiO3 (NBT-5.6%BT) were investigated. X-ray diffraction revealed two types of diffuse scattering in NBT: (i) broad and (ii) asymmetric L-shaped. After modification with 5.6%BT, the broad diffuse scattering patterns became narrow, and the asymmetric L-shaped ones were replaced by symmetric ones. The symmetric diffuse scattering in NBT-5.6%BT disappeared with increasing dc electric field (E) for E ? 9.5 kV/cm where the frequency dispersion in the dielectric constant disappeared. These results demonstrate that the relaxor characteristics are directly correlated with the diffuse scattering and the presence polar nano-regions.

  3. Effects of Niobium Addition on the Relaxor Ferroelectric Properties and Ordering Structures of Lead Iron Tantalates

    Microsoft Academic Search

    Byong-Chul Woo; Byung-Kook Kim

    2003-01-01

    Pyrochlore-free Pb(Fe1\\/2Ta1\\/2)O3, Pb(Fe1\\/2Nb1\\/2)O3, and complete series of solid solutions between them were fabricated and their ordering structures as well as their dielectric properties were investigated. The dielectric properties of Pb(Fe1\\/2Ta1\\/2)O3 were those of typical relaxor ferroelectrics showing evident dielectric relaxation and diffusive phase transition, but the degrees of diffusive phase transition and dielectric relaxation decreased as Ta5+ was replaced by

  4. Study of Three Different Relaxor Ferroelectrics by High Resolution Micro-Brillouin Scattering

    Microsoft Academic Search

    Fuming M. Jiang; Seiji Kojima

    2000-01-01

    Three different relaxor ferroelectrics, 0.65PMN-0.35PT, Sr0.61Ba0.39Nb2O6 (SBN), and Pb0.85La0.1Zr0.65Ti0.35O3 have been studied by Brillouin scattering using a microscope with a focal point of 1-2 mum. Relaxation modes have been directly observed for the first time for all three samples. They form at a temperature much higher than the reported dielectric maximum temperature Tm. Thermal evolution of the polar microregions has

  5. Pressure as a probe of the physics of ABO{sub 3} relaxor ferroelectrics

    SciTech Connect

    SAMARA,GEORGE A.

    2000-02-14

    Results on a variety of mixed ABO{sub 3} oxides have revealed a pressure-induced ferroelectric-to-relaxor crossover and the continuous evolution of the energetics and dynamics of the relaxation process with increasing pressure. These common features have suggested a mechanism for the crossover phenomenon in terms of a large decrease in the correlation length for dipolar interactions with pressure--a unique property of soft mode or highly polarizable host lattices. The pressure effects as well as the interplay between pressure and dc biasing fields are illustrated for some recent results on PZN-9.5 PT,PMN and PLZT 6/65/35.

  6. Change from 3D-Ising to Random Field-Ising-Model Criticality in a Uniaxial Relaxor Ferroelectric

    E-print Network

    Osnabrück, Universität

    Change from 3D-Ising to Random Field-Ising-Model Criticality in a Uniaxial Relaxor Ferroelectric T piezoelectric sensors or actuators, where ceramics of lead zirconate titanate (PZT) or lead lanthanum zirconate titanate (PLZT) are extensively used [3], to optical applications like phase conjugated mirrors, where

  7. High performance relaxor-based ferroelectric single crystals for ultrasonic transducer applications.

    PubMed

    Chen, Yan; Lam, Kwok-Ho; Zhou, Dan; Yue, Qingwen; Yu, Yanxiong; Wu, Jinchuan; Qiu, Weibao; Sun, Lei; Zhang, Chao; Luo, Haosu; Chan, Helen L W; Dai, Jiyan

    2014-01-01

    Relaxor-based ferroelectric single crystals Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) have drawn much attention in the ferroelectric field because of their excellent piezoelectric properties and high electromechanical coupling coefficients (d33~2000 pC/N, kt~60%) near the morphotropic phase boundary (MPB). Ternary Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 (PIN-PMN-PT) single crystals also possess outstanding performance comparable with PMN-PT single crystals, but have higher phase transition temperatures (rhombohedral to tetragonal Trt, and tetragonal to cubic Tc) and larger coercive field Ec. Therefore, these relaxor-based single crystals have been extensively employed for ultrasonic transducer applications. In this paper, an overview of our work and perspectives on using PMN-PT and PIN-PMN-PT single crystals for ultrasonic transducer applications is presented. Various types of single-element ultrasonic transducers, including endoscopic transducers, intravascular transducers, high-frequency and high-temperature transducers fabricated using the PMN-PT and PIN-PMN-PT crystals and their 2-2 and 1-3 composites are reported. Besides, the fabrication and characterization of the array transducers, such as phased array, cylindrical shaped linear array, high-temperature linear array, radial endoscopic array, and annular array, are also addressed. PMID:25076222

  8. Crossover from ferroelectric to relaxor and cluster glass in BaTi1-xZrxO3 (x = 0.25-0.35) studied by non-linear permittivity

    NASA Astrophysics Data System (ADS)

    Kleemann, W.; Miga, S.; Dec, J.; Zhai, J.

    2013-06-01

    The electric susceptibilities ?1, ?2, and ?3 of BaTi1-xZrxO3 ceramics with 0.25 ? x ? 0.35 are measured at 90 ? T ? 350 K and 37 ? f ? 106 Hz. Crossover from ferroelectric (x = 0.25) to relaxor behavior (x = 0.35) via coexistence of both (x = 0.30) is indicated by increasing polydispersivity and suppression of ?2 intensity and negative ?3 tails. The relaxor properties are due to weak random fields acting on dipolar Ti4+ clusters in non-polar Zr4+ environment. Frustrated interaction between blocked polar nanoregions yields a cluster glass ground state for x = 0.35.

  9. Pulsed laser deposition of relaxor ferroelectric lead magnesium niobate-lead titanate thin films and heterostructures

    NASA Astrophysics Data System (ADS)

    Lavric, Dan Silviu

    Since their discovery several decades ago, relaxor ferroelectrics (RFE) (1- x)Pb(Mg1/3Nb2/3)O3- xPbTiO3 (PMN-PT), engineered near the morphotropic phase boundary (x = 0.3), have raised tremendous interest in the ferroelectric community, due to their broad ferroelectric transition, enormous dielectric constant, high piezoelectric coefficients and exceptional electromechanical coupling factors. However, these attractive qualities were demonstrated mainly by PMN-PT single crystals and ceramics and scarcely at all by PMN-PT thin films. This thesis addresses critical issues of the pulsed laser deposition growth of high quality epitaxial 0.70PMN-0.30PT thin films and heterostructures, for potential ferroelectric and piezoelectric thin film applications. A review of relaxor ferroelectrics in terms of general characteristics, crystallographic structure, models and synthesis with a special emphasis on 0.70PMN-0.30PT solid solutions is presented, including current issues of the Pulsed Laser Deposition (PLD) method, highlighting particular problems of lead-compound synthesis. The development of two pulsed laser deposition systems, two six target carousels, a target motion amplifier, an inverse position arm sputtering system, one He-Ne laser alignment system and one shadow mask set are described. These systems have been used for the growth of epitaxial RFE PMN-PT thin films and heterostructures. The main issues regarding the growth of pure perovskite phase single crystal PMN-PT/(001)SrTiO3 thin films and PMN-PT/SrRuO3/(001)SrTiO 3 heterostructures by PLD, the optimized deposition parameter space for in-situ growth, and the structural and chemical characterization of high quality PMN-PT thin films and heterostructures are addressed. Epitaxial PMN-PT thin films and heterostructures of unprecedented quality, resembling that of bulk single crystals are reported, and the thickness dependences of the strain state and crystalline quality are established. A film-growth, self-regulatory mechanism was found to adjust the non-stoichiometric atomic flux coming from the off-stoichiometric PMN-PT targets to form the perovskite phase when lower deposition rates were used. Laser instabilities and their impact upon the films reproducibility are discussed. Dielectric and piezoelectric measurements performed on PMN-PT thin films, together with the factors that influence these measurements, are presented. The thickness dependences of dielectric and ferroelectric parameters is reported. Annealing treatments in high oxygen pressure are shown to improve film dielectric and ferroelectric properties. Thicker films demonstrate the highest room temperature dielectric constants (? = 12000) and ferroelectric properties (remnant polarization Pr = 20 ?C/cm2, coercive field EC = 10 KV/cm, saturation polarization PS = 38 ?C/cm2, saturation field ES = 30 KV/cm) ever reported for a PMN- PT film, regardless of the deposition method involved. The piezoelectric charge coefficient at high fields is found to be d33 = 30 pm/V.

  10. Relaxor-based ferroelectric single crystals: growth, domain engineering, characterization and applications.

    PubMed

    Sun, Enwei; Cao, Wenwu

    2014-08-01

    In the past decade, domain engineered relaxor-PT ferroelectric single crystals, including (1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-PT), (1-x)Pb(Zn1/3Nb2/3)O3-xPbTiO3 (PZN-PT) and (1-x-y)Pb(In1/2Nb1/2)O3-yPb(Mg1/3Nb2/3)O3-xPbTiO3 (PIN-PMN-PT), with compositions near the morphotropic phase boundary (MPB) have triggered a revolution in electromechanical devices owing to their giant piezoelectric properties and ultra-high electromechanical coupling factors. Compared to traditional PbZr1-x Ti x O3 (PZT) ceramics, the piezoelectric coefficient d 33 is increased by a factor of 5 and the electromechanical coupling factor k 33 is increased from < 70% to > 90%. Many emerging rich physical phenomena, such as charged domain walls, multi-phase coexistence, domain pattern symmetries, etc., have posed challenging fundamental questions for scientists. The superior electromechanical properties of these domain engineered single crystals have prompted the design of a new generation electromechanical devices, including sensors, transducers, actuators and other electromechanical devices, with greatly improved performance. It took less than 7 years from the discovery of larger size PMN-PT single crystals to the commercial production of the high-end ultrasonic imaging probe "PureWave". The speed of development is unprecedented, and the research collaboration between academia and industrial engineers on this topic is truly intriguing. It is also exciting to see that these relaxor-PT single crystals are being used to replace traditional PZT piezoceramics in many new fields outside of medical imaging. The new ternary PIN-PMN-PT single crystals, particularly the ones with Mn-doping, have laid a solid foundation for innovations in high power acoustic projectors and ultrasonic motors, hinting another revolution in underwater SONARs and miniature actuation devices. This article intends to provide a comprehensive review on the development of relaxor-PT single crystals, spanning material discovery, crystal growth techniques, domain engineering concept, and full-matrix property characterization all the way to device innovations. It outlines a truly encouraging story in materials science in the modern era. All key references are provided and 30 complete sets of material parameters for different types of relaxor-PT single crystals are listed in the Appendix. It is the intension of this review article to serve as a resource for those who are interested in basic research and practical applications of these relaxor-PT single crystals. In addition, possible mechanisms of giant piezoelectric properties in these domain-engineered relaxor-PT systems will be discussed based on contributions from polarization rotation and charged domain walls. PMID:25061239

  11. Scale effects of low-dimensional relaxor ferroelectric single crystals and their application in novel pyroelectric infrared detectors.

    PubMed

    Li, Long; Zhao, Xiangyong; Li, Xiaobing; Ren, Bo; Xu, Qing; Liang, Zhu; Di, Wenning; Yang, Linrong; Luo, Haosu; Shao, Xiumei; Fang, Jiaxiong; Neumann, Norbert; Jiao, Jie

    2014-04-23

    Scaling effects of low-dimensional relaxor ferroelectric single crystals have induced large delocalization of domain switching, leading to a dramatic increase in pyro-electric performances by 2-5.5 times, and promoting the detectivity of fabricated pyroelectric detectors to an international leading level of 2.21 × 10(9) cmHz(1/2) /W at 10 Hz, 4 times higher than that of commercial LiTaO3 -based detectors. PMID:24497438

  12. Strain-induced long range ferroelectric order and linear electro-optic effect in epitaxial relaxor thin films

    NASA Astrophysics Data System (ADS)

    Scarisoreanu, N. D.; Craciun, F.; Birjega, R.; Andrei, A.; Ion, V.; Negrea, R. F.; Ghica, C.; Dinescu, M.

    2014-08-01

    Relaxor ferroelectrics have neither long range ferroelectric order nor structural transformation down to the lowest temperatures, and display isotropic optical properties like quadratic electro-optic effect. However, if an anisotropy is forced through an external agent, like electric field or uniaxial strain, a ferroelectric and structural long range order can be induced in these materials. Here, we show that epitaxial strain in relaxor ferroelectric thin films can be employed to induce a linear electro-optic effect, opening the path to new strain-controlled electro-optic materials. Epitaxial thin films with Pb1-3x/2LaxZr0.2Ti0.8O3 (x = 0.22) composition grown by pulsed laser deposition on (001) SrRuO3/SrTiO3 single crystal heterostructures become tetragonal below the susceptibility peak, which occurs at a temperature 140 K higher as compared to bulk. These films show piezoelectric properties and almost linear electro-optic behaviour.

  13. High temperature lead-free relaxor ferroelectric: Intergrowth Aurivillius phase BaBi{sub 2}Nb{sub 2}O{sub 9}-Bi{sub 4}Ti{sub 3}O{sub 12} ceramics

    SciTech Connect

    Zhang Hongtao [School of Engineering and Materials Science, Queen Mary University of London, London E1 4NS (United Kingdom); Department of Materials, University of Oxford, Oxford OX1 3PH (United Kingdom); Yan Haixue; Reece, Michael J. [School of Engineering and Materials Science, Queen Mary University of London, London E1 4NS (United Kingdom); Nanoforce Technology Ltd., London E1 4NS (United Kingdom)

    2010-05-15

    Intergrowth BaBi{sub 2}Nb{sub 2}O{sub 9}-Bi{sub 4}Ti{sub 3}O{sub 12} (BaBi{sub 6}Ti{sub 3}Nb{sub 2}O{sub 21}) Aurivillius phase ceramic has been found to be a relaxor ferroelectric (RFE) with the highest reported temperature of the maximum of the dielectric permittivity (T{sub m}) of all of the known RFE systems. Dielectric characterization revealed that it has two dielectric anomalies. The first one is a frequency independent broad dielectric constant peak at {approx}280 deg. C, while the second anomaly shows relaxor behavior at 636 deg. C (100 kHz). There is obvious frequency dispersion of dielectric response at room temperature, which is in agreement with dielectric properties of a typical relaxor. Ferroelectric hysteresis loops and a measurable value of piezoelectric constant d{sub 33} confirmed the ferroelectric nature of BaBi{sub 6}Ti{sub 3}Nb{sub 2}O{sub 21} ceramics. The piezoelectric response remained even after annealing at temperatures above 636 deg. C.

  14. Compositional disorder, polar nanoregions and dipole dynamics in Pb(Mg1/3Nb2/3)O3-based relaxor ferroelectrics

    SciTech Connect

    Bokov, Alexei A. [Simon Fraser University, Canada; Rodriguez, Brian [University College, Dublin; Zhao, X [Iowa State University; Ko, JH [Hallym University, Korea; Jesse, Stephen [ORNL; Long, X [Simon Fraser University, Canada; Qu, W [Iowa State University; Kim, TH [Hallym University, Korea; Budai, John D [ORNL; Morozovska, A. N. [National Academy of Science of Ukraine, Kiev, Ukraine; Kojima, S [University of Tsukuba, Japan; Tan, X [Iowa State University; Kalinin, Sergei V [ORNL; Ye, Z.-G. [Simon Fraser University, Canada

    2011-01-01

    The complex structure of relaxor ferroelectrics comprises polar nanoregions (PNRs) which appear upon cooling below the Burns temperature and quenched compositional (chemical) disorder. The relation between the polar nanostructure and compositionally ordered regions (CORs) often observed in relaxors has been the subject of extensive theoretical investigations; however, the experimental data, especially concerning Pb(B0 1=3B00 2=3)O3-type complex perovskite relaxors, are rather limited. In this paper, we analyse and discuss the results of our recent investigations of the morphology of CORs and the dynamics of PNRs in Pb(Mg1/3Nb2/3)O3-based solid solutions in which the degree of compositional disorder was varied by means of changing the composition and/or by means of high-temperature annealing. The samples were characterised using X-ray diffraction, transmission electron microscopy, piezoresponse force microscopy, Brillouin light scattering, dielectric spectroscopy, as well as by measuring pyroelectric effect and ferroelectric hysteresis loops. No influence of the size of CORs on the PNRs relaxation in the ergodic relaxor phase is found. Instead, the CORs size influences significantly the diffuseness of the transition from the field-induced ferroelectric phase to the ergodic relaxor state. The results are interpreted in the framework of a model suggesting the coexistence of static and dynamic PNRs in the ergodic relaxor phase.

  15. Electromechanical properties of relaxor ferroelectric P(VDF-TrFE-CFE)-P(VDF-CTFE) blends.

    PubMed

    Gorny, Lee J; Lu, Sheng-Guo; Liu, Sheng; Lin, Minren

    2013-03-01

    Electromechanical properties of the relaxor ferroelectric poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) [P(VDF-TrFE-CFE)] terpolymer blended with a small amount of poly(vinylidene fluoride-chlorotrifluoroethylene) [P(VDF-CTFE)] copolymer, which possesses a much higher elastic modulus than that of the neat terpolymer, were investigated. It was observed that the presence of small amount of P(VDF-CTFE) does not affect the microstructure of the crystalline phase. However, the uniaxially stretched blended films show a slight increase in the crystallinity and increased or similar induced polarization at high electric fields compared with the neat terpolymer, likely caused by the interface effect. Consequently, for blends with P(VDF-CTFE) less than 5 wt%, the transverse strains S1 along the stretching direction for uniaxially stretched blended films are nearly the same as those of neat P(VDF-TrFE-CFE), whereas the elastic modulus along the S1-direction increases with the P(VDF-CTFE) content. As a result, the blended films exhibit a higher elastic energy density and electromechanical coupling factor k31 compared with the neat terpolymer. PMID:23475911

  16. Origin of the crossover between a freezing and a structural transition at low concentration in the relaxor ferroelectric K1 -xLixTaO3

    NASA Astrophysics Data System (ADS)

    Cai, Ling; Toulouse, Jean; Harriger, Leland; Downing, R. Gregory; Boatner, L. A.

    2015-04-01

    The origin of the relaxor behavior in K1 -xLixTaO3(KLT ) and other disordered perovskites is now recognized to be due to the reorientation of the polar nanodomains formed by the correlated dipoles of off-center ions. The collective dynamics of these systems evolve through several temperature stages. On decreasing temperature below the so-called Burns temperature TB, individual dipoles become correlated within nanosized regions. On further cooling, the slow dynamics of these polar regions allows local lattice distortions to take place and the formation of polar nanodomains at T*relaxors undergo a phase transition while others do not. In KLT, there is a critical Li concentration xc=0.022 above which the system undergoes a structural transition at Tc, and below which it freezes in a dipole glass state at Tf. To better understand the nature of this critical concentration, the changes that occur upon crossing it and the nature of the dipole glass state, the collective dynamics of KLT have been studied by dielectric spectroscopy and neutron diffraction for two Li concentrations (x =0.026 and 0.018 ) , close to but straddling the critical concentration xc. Two very different transitional behaviors are observed. Just below this critical concentration, KLT displays critical slowing down and the onset of freezing as seen in hydrogen-bonded molecular ferroelectrics, while just above this concentration, KLT undergoes a first-order structural transition.

  17. A relaxor ferroelectric single crystal cut resulting in large d312 and zero d311 for a shear mode accelerometer and related applications

    NASA Astrophysics Data System (ADS)

    Goljahi, S.; Gallagher, J.; Zhang, S. J.; Luo, J.; Sahul, R.; Hackenberger, W.; Lynch, C. S.

    2012-05-01

    Relaxor ferroelectric single crystals exhibit anisotropic piezoelectric behavior. This enables the use of a combination of crystal cut and poling to obtain piezoelectric properties optimized for certain applications. This work describes a crystal cut that is optimized for applications where a strong face shear mode d312 coupling is desired with a zero d311 or zero d322 piezoelectric coefficient. Such a crystal cut enables the production of stack actuators in a long bar shape with the electric field perpendicular to the bar length. These bars can be cantilevered with a mass at the end to produce a highly sensitive shear mode accelerometer. The zero value of d311 or d322 eliminates a possible extensional mode coupling along the length of the bar. Only one of d311 or d322 can be made equal to zero, the other having a negative value.

  18. Effects of lanthanum dopants on the Curie–Weiss and the local order behaviors for Pb{sub 1?x}La{sub x}(Fe{sub 2/3}W{sub 1/3}){sub 0.7}Ti{sub 0.3}O{sub 3} relaxor ferroelectrics

    SciTech Connect

    Hong, Cheng-Shong, E-mail: cshong@nknu.edu.tw [Department of Electronic Engineering, National Kaohsiung Normal University, Kaohsiung 824, Taiwan, ROC (China)] [Department of Electronic Engineering, National Kaohsiung Normal University, Kaohsiung 824, Taiwan, ROC (China); Chu, Sheng-Yuan, E-mail: chusy@mail.ncku.edu.tw [Department of Electrical Engineering, National Cheng Kung University, Tainan 701, Taiwan, ROC (China) [Department of Electrical Engineering, National Cheng Kung University, Tainan 701, Taiwan, ROC (China); Center for Micro/Nano Science and Technology, National Cheng Kung University, Tainan 701, Taiwan, ROC (China); Tsai, Cheng-Che [Department of Electronics Engineering and Computer Science, Tung Fang Design University, Kaohsiung 829, Taiwan, ROC (China)] [Department of Electronics Engineering and Computer Science, Tung Fang Design University, Kaohsiung 829, Taiwan, ROC (China); Hsu, Chi-Cheng; Su, Hsiu-Hsien [Department of Electrical Engineering, National Cheng Kung University, Tainan 701, Taiwan, ROC (China)] [Department of Electrical Engineering, National Cheng Kung University, Tainan 701, Taiwan, ROC (China)

    2013-02-15

    Graphical abstract: The local order as a function of temperature by using (a) the spin-glass model and (b) the modified-Landau theory for Pb{sub 1?x}La{sub x}(Fe{sub 2/3}W{sub 1/3}){sub 0.7}Ti{sub 0.3}O{sub 3} ceramics with different amounts of lanthanum dopants. Display Omitted Highlights: ? The effects of La are investigated for Pb{sub 1?x}La{sub x}(Fe{sub 2/3}W{sub 1/3}){sub 0.7}Ti{sub 0.3}O{sub 3} ceramics. ? La can change their dielectric properties and ordering state. ? The spin glassy behaviors and the freezing process are also affected by La. ? The response mechanisms of La are proposed for the local polarization behavior. -- Abstract: The effects of lanthanum dopants are investigated on the dielectric responses for Pb{sub 1?x}La{sub x}(Fe{sub 2/3}W{sub 1/3}){sub 0.7}Ti{sub 0.3}O{sub 3} ceramics. According to the experimental data and fitting results, it is concluded that the dielectric characteristics are changed from a long-range-ordered (LRO) ferroelectric state to a short-range-ordered (SRO) relaxor by increasing the amounts of lanthanum dopants. Furthermore, the spin glassy behaviors and the freezing process of local polarizations are not only affected by the ordering degree of B-site cations but also affected by the defect polar pairs. Their response mechanisms are proposed that the growth of the 1:1 ordered domain Pb{sub 1?x}La{sub x}(Fe{sub 1/2}W{sub 1/2})O{sub 3} is impeded since its charge imbalance is enhanced by increasing the amounts of lanthanum dopants, and the defect polar pairs of lead, tungsten and oxygen vacancy are induced by the pyrochlore phase, PbWO{sub 4} or Pb{sub 0.99}La{sub 0.01}WO{sub 4}, when the amount of lanthanum dopants exceed 5 mol.%.

  19. Phase transformation via a monoclinic phase in relaxor-based ferroelectric crystal ,,PbMg13Nb23O3...1x,,PbTiO3...x

    E-print Network

    Phase transformation via a monoclinic phase in relaxor-based ferroelectric crystal ,,PbMg1Õ3Nb2Õ3O3.020102 PACS number s : 77.80.Dj, 77.80.Bh Relaxor-based ferroelectric FE crystals (PbMg1/3Nb2/3O3)1 x(PbTiO3)x rotation from 111 to 001 will be largely cancelled in randomly oriented ceramics.14 These phenomena open

  20. Widely tunable reflection-type Fabry-Perot interferometer based on relaxor ferroelectric poly(vinylidenefluoride-chlorotrifluoroethylene-trifluoroethylene).

    PubMed

    Zhen, Hongyu; Ye, Hui; Liu, Xu; Zhu, Dexi; Li, Haifeng; Lu, Yingying; Wang, Qing

    2008-06-23

    A reflection-type Fabry-Perot interferometer (FPI) with a large tunability has been demonstrated on relaxor ferroelectric poly(vinylidenefluoride-chlorotrifluoroethylene-trifluoroethylene) [P(VDFCTFE-TrFE)] 78.9/13.9/7.2 mol% with a thickness of 9.2 microm. The optical path length of the FPI is modulated by the electrostrictive strain of the terpolymer under electric field, where the low-loss distributed Bragg reflector and aluminium film are employed as the mirrors in the FPI. A positive strain of 20% has been achieved in the terpolymer film under a field of 30 MV/m, which leads to the FPI with a tunable range of more than 200 nm at wavelengths around 680 nm. PMID:18575527

  1. Thermal conductivity and heat capacity of the relaxor ferroelectric [PbMg1/3Nb2/3O3]1-x[PbTiO3]x

    NASA Astrophysics Data System (ADS)

    Tachibana, Makoto; Takayama-Muromachi, Eiji

    2009-03-01

    The evolution of thermal conductivity and heat capacity for the series of [PbMg1/3Nb2/3O3]1-x[PbTiO3]x (PMN-PTx) single crystals with 0?x?1 are reported. PMN shows typical glasslike behavior in both measurements, which is attributed to the presence of polar nanoregions. With PT doping up to the region of morphotropic phase boundary (MPB), the plateau in thermal conductivity is progressively suppressed. This is reminiscent of partially crystallized glasses and suggests enhanced thermal boundary resistance from ferroelectric domains. The linear temperature contribution and large Cp/T3 peak in heat capacity remain nearly constant for PT doping up to the MPB but are rapidly suppressed for larger x . These results demonstrate that thermal properties are intimately coupled to the local structures in relaxor ferroelectric systems.

  2. Temperature-dependent dielectric nonlinearity of relaxor ferroelectric Pb0.92La0.08Zr0.52Ti0.48O3 thin films

    NASA Astrophysics Data System (ADS)

    Ma, Beihai; Hu, Zhongqiang; Liu, Shanshan; Tong, Sheng; Narayanan, Manoj; Koritala, Rachel E.; Balachandran, Uthamalingam

    2013-05-01

    Rayleigh analysis has been used to investigate the temperature dependence of the dielectric response of relaxor ferroelectric Pb0.92La0.08Zr0.52Ti0.48O3 films grown on platinized silicon substrates by chemical solution deposition. The irreversible contribution to dielectric permittivity maximizes at 50 °C and decreases with further temperature increase; while the intrinsic/reversible contribution is weakly dependent on temperature. The relaxor ferroelectric transition temperature Tm increases from 160 °C to 172 °C when the frequency increases from 1 kHz to 100 kHz. The dielectric nonlinearity decreases with temperature: falling from 0.012 cm/kV at room temperature to 0.005 cm/kV at 225 °C in tests at 1 kHz.

  3. (100) MgAl2O4 as a lattice-matched substrate for the epitaxial thin film deposition of the relaxor ferroelectric PMN-PT

    NASA Astrophysics Data System (ADS)

    Keogh, D.; Chen, Z.; Hughes, R. A.; Dabkowski, A.; Marinov, O.; Maunders, C.; Gunawan, L.; Deen, M. J.; Preston, J. S.; Botton, G. A.

    2010-01-01

    The (100) surface of MgAl2O4 is evaluated as a substrate for the thin film deposition of the relaxor ferroelectric PbMg1/3Nb2/3O3(65%)-PbTiO3(35%). With a lattice mismatch of less than 0.5%, this film-substrate combination presents a geometrical template for growth that is far superior to that formed with other commercially available oxide substrates. Films were deposited using the pulsed laser deposition technique and were characterized in terms of their crystallographic, microstructural, and dielectric properties. From a crystallographic perspective the films show excellent cube-on-cube epitaxy, are highly oriented, and show no evidence of the frequently observed parasitic pyrochlore phase. With the exception of a few faceted surface structures, the film’s microstructure is single-crystal-like, exhibiting a sharp film-substrate interface, a smooth top surface, and no discernable granularity. The dielectric response shows the frequency-dependent diffuse phase transition characteristic of a relaxor material, but with less frequency dispersion and a smaller maximum in the dielectric constant. Taken together, the results suggest that the (100) MgAl2O4 substrate could prove to be an effective substrate material, not only for the PbMg1/3Nb2/3O3(65%)-PbTiO3(35%) system, but also for a number of other important lattice-matched ferroelectric, relaxor, and ferroelectric superlattice systems.

  4. Bulk relaxor ferroelectric ceramics as a working body for an electrocaloric cooling device

    NASA Astrophysics Data System (ADS)

    Plaznik, Uroš; Kitanovski, Andrej; Roži?, Brigita; Mali?, Barbara; Urši?, Hana; Drnovšek, Silvo; Cilenšek, Jena; Vrabelj, Marko; Poredoš, Alojz; Kutnjak, Zdravko

    2015-01-01

    The electrocaloric effect (ECE), i.e., the conversion of the electric into the thermal energy has recently become of great importance for development of a new generation of cooling technologies. Here, we explore utilization of [Pb(Mg1/3Nb2/3)O3]0.9[PbTiO3]0.1 (PMN-10PT) relaxor ceramics as active elements of the heat regenerator in an ECE cooling device. We show that the PMN-10PT relaxor ceramic exhibits a relatively large electrocaloric change of temperature ?TEC > 1 K at room temperature. The experimental testing of the cooling device demonstrates the efficient regeneration and establishment of the temperature span between the hot and the cold sides of the regenerator, exceeding several times the ?TEC within a single PMN-10PT ceramic plate.

  5. Ergodicity reflected in macroscopic and microscopic field-dependent behavior of BNT-based relaxors

    NASA Astrophysics Data System (ADS)

    Dittmer, Robert; Gobeljic, Danka; Jo, Wook; Shvartsman, Vladimir V.; Lupascu, Doru C.; Jones, Jacob L.; Rödel, Jürgen

    2014-02-01

    The effect of heterovalent B-site doping on ergodicity of relaxor ferroelectrics is studied using (1 - y)(0.81Bi1/2Na1/2TiO3-0.19Bi1/2K1/2TiO3)-yBiZn1/2Ti1/2O3 (BNT-BKT-BZT) with y = {0.02;0.03;0.04} as a model system. Both the large- and small-signal parameters are studied as a function of electric field. The crystal structure is assessed by means of neutron diffraction in the initial state and after exposure to a high electric field. In order to measure ferroelastic domain textures, diffraction patterns of the poled samples are collected as a function of sample rotation angle. Piezoresponse force microscopy (PFM) is employed to probe the microstructure for polar regions at a nanoscopic scale. For low electric fields E < 2 kV.mm-1, large- and small-signal constitutive behavior do not change with composition. At high electric fields, however, drastic differences are observed due to a field-induced phase transition into a long-range ordered state. It is hypothesized that increasing BZT content decreases the degree of non-ergodicity; thus, the formation of long-range order is impeded. It is suggested that frozen and dynamic polar nano regions exist to a different degree, depending on the BZT content. This image is supported by PFM measurements. Moreover, PFM measurements suggest that the relaxation mechanism after removal of the bias field is influenced by surface charges.

  6. Visualization of polar nanoregions in lead-free relaxors via piezoresponse force microscopy in torsional dual AC resonance tracking mode.

    PubMed

    Liu, Na; Dittmer, Robert; Stark, Robert W; Dietz, Christian

    2015-07-21

    Polar nanoregions (PNRs) play a key role in the functionality of relaxor ferroelectrics; however, visualizing them in lead-free relaxor ferroelectrics with high lateral resolution is still challenging. Thus, we studied herein the local ferroelectric domain distribution of the lead-free bismuth-based (1 -x)(Bi1/2Na1/2TiO3-Bi1/2K1/2TiO3) -x(Bi1/2Mg1/2TiO3) piezoceramics which show a relaxor behavior using dual AC resonance tracking (DART) piezoresponse force microscopy (PFM). By using excitation frequencies at either side of the contact resonance peak of the torsional cantilever vibration, an enhanced contrast in the amplitude and phase images of the piezoresponse can be achieved. Additionally, this tracking technique reduces the topographical crosstalk while mapping the local electromechanical properties. The true drive amplitude, drive phase, contact resonant frequency and quality factor can be estimated from DART-PFM data obtained with vertically or torsionally vibrating cantilevers. This procedure yields a three-dimensional quantitative map of the local piezoelectric properties of the relaxor ferroelectric samples. With this approach, torsional DART allowed for the visualization of fine substructures within the monodomains, suggesting the existence of PNRs in relaxor ferroelectrics. The domain structures of the PNRs were visualized with high precision, and the local electromechanical characteristics of the lead-free relaxor ferroelectrics were quantitatively mapped. PMID:26106953

  7. Blockage of domain growth by nanoscale heterogeneities in a relaxor ferroelectric Sr0.61Ba0.39Nb2O6

    NASA Astrophysics Data System (ADS)

    Pertsev, N. A.; Gainutdinov, R. V.; Bodnarchuk, Ya. V.; Volk, T. R.

    2015-01-01

    The growth of localized subsurface domains in a relaxor ferroelectric Sr0.61Ba0.39Nb2O6 is studied using the technique of piezoresponse force microscopy (PFM). Ferroelectric domains are created by applying moderate voltages of 10-50 V to the conductive tip of a scanning force microscope brought into contact with a nonpolar face of a Sr0.61Ba0.39Nb2O6 crystal. PFM images of written domains are acquired and analyzed quantitatively to determine the domain length along the polar axis and its width in the transverse direction. The dependences of domain sizes on the applied voltage, pulse duration, and the time passed after completion of the voltage pulse are reported and analyzed theoretically. It is shown that the observed kinetics of domain growth can be explained by the creep of domain boundaries occurring in the presence of random electric fields inherent in Sr0.61Ba0.39Nb2O6. The comparison of measured domain sizes with their equilibrium values calculated with the aid of the thermodynamic theory demonstrates that the growth of subsurface domains in Sr0.61Ba0.39Nb2O6 is blocked by nanoscale heterogeneities characteristic of this relaxor ferroelectric. These results may have important implications for the development of nonlinear optical devices based on nanoheterogeneous ferroelectrics.

  8. Ferroelectric and electromechanical properties of poly(vinylidene-fluoride-trifluoroethylene-chlorotrifluoroethylene) terpolymer

    NASA Astrophysics Data System (ADS)

    Xu, Haisheng; Cheng, Z.-Y.; Olson, Dana; Mai, T.; Zhang, Q. M.; Kavarnos, G.

    2001-04-01

    This letter reports the ferroelectric and electromechanical properties of a class of ferroelectric polymer, poly(vinylidene-fluoride-trifluoroethylene-chlorotrifluoroethylene) terpolymer, which exhibits a slim polarization hysteresis loop and a high electrostrictive strain at room temperature. The dielectric and polarization behaviors of this terpolymer are typical of the ferroelectric relaxor. The x-ray and Fourier transform infrared results reveal that the random incorporation of bulky chlorotrifluoroethylene (CTFE) ter-monomers into polymer chains causes disordering of the ferroelectric phase. Furthermore, CTFE also acts as random defect fields which randomize the inter- and intrachain polar coupling, resulting in the observed ferroelectric relaxor behavior.

  9. Octahedral tilt transitions in the relaxor ferroelectric Na1/2Bi1/2TiO3

    NASA Astrophysics Data System (ADS)

    Meyer, Kai-Christian; Gröting, Melanie; Albe, Karsten

    2015-07-01

    The kinetics of octahedral tilt transitions in the lead-free relaxor material sodium bismuth titanate Na1/2Bi1/2TiO3 (NBT) is investigated by electronic structure calculations within density functional theory. Energy barriers for transitions between tetragonal, rhombohedral and orthorhombic tilts in cation configurations with [001]- and [111]-order on the A-sites are determined by nudged elastic band calculations. By tilting entire layers of octahedra simultaneously we find that the activation energy is lower for structures with 001-order compared to such with 111-order. The energetic coupling between differently tilted layers is, however, negligibly small. By introducing a single octahedral defect we create local tilt disorder and find that the deformation energy of the neighboring octahedra is less in a rhombohedral than in a tetragonal structure. By successively increasing the size of clusters of orthorhombic defects in a rhombohedral matrix with 001-order, we determine a critical cluster size of about 40 Å . Thus groups of about ten octahedra can be considered as nuclei for polar nanoregions, which are the cause of the experimentally observed relaxor behavior of NBT.

  10. Origin of high-temperature relaxor-like behavior in CaCu3Ti4O12

    NASA Astrophysics Data System (ADS)

    Wang, Chun-Chang; Zhang, Mei-Ni; Xu, Ke-Biao; Wang, Guo-Jing

    2012-08-01

    The relaxor-like behavior in CaCu3Ti4O12 was investigated in details. The dielectric anomaly was found to be an extrinsic phenomenon related to oxygen vacancy. Annealing treatments in N2 and O2 atmospheres revealed that the relaxor-like behavior is composed of two types of relaxations with close relaxation parameters. Impedance analysis showed that the relaxations appearing in the low- and high-temperature wings of the anomaly are related to the dipolar and Maxwell-Wagner (MW) relaxation, respectively. Both relaxations are induced by the hopping motions of confined carriers related to single-ionized oxygen vacancies, and they are intimately linked with each other. The relaxor-like anomaly is attributed to the combining effect of these two relaxations, i.e., the dipolar relaxation first creates a steplike increase followed by a rapid decrease in dielectric constant caused by the MW relaxation, thereby, giving rise to the relaxor-like behavior.

  11. Polarization behavior of ferroelectric multilayered composite structures

    Microsoft Academic Search

    Y. T; C. K. Wong; B. Ploss; F. G. Shin

    2003-01-01

    We model the polarization behavior of ferroelectric multilayered composite structures including the double layer and the triple layer under the action of variable fields. The model takes into consideration the ceramic\\/polymer interfacial charge and the nonlinear hysteresis nature of the ferroelectric constituent materials to study the poling process of multilayered structures. The results obtained are compared with available experimental results

  12. Relaxor ferroelectricity and colossal magnetocapacitive coupling in ferromagnetic CdCr2S4

    Microsoft Academic Search

    J. Hemberger; P. Lunkenheimer; R. Fichtl; H.-A. Krug von Nidda; V. Tsurkan; A. Loidl

    2005-01-01

    Materials in which magnetic and electric order coexist-termed `multiferroics' or `magnetoelectrics'-have recently become the focus of much research. In particular, the simultaneous occurrence of ferromagnetism and ferroelectricity, combined with an intimate coupling of magnetization and polarization via magnetocapacitive effects, holds promise for new generations of electronic devices. Here we present measurements on a simple cubic spinel compound with unusual, and

  13. Large enhancement of energy-storage properties of compositional graded (Pb1-xLax)(Zr0.65Ti0.35)O3 relaxor ferroelectric thick films

    NASA Astrophysics Data System (ADS)

    Zhang, Liwen; Hao, Xihong; Yang, Jichun; An, Shengli; Song, Bo

    2013-09-01

    In this letter, the compositionally graded multilayer (Pb1-xLax)(Zr0.65Ti0.35)O3 (PLZT) relaxor ferroelectric thick films were fabricated on LaNiO3/Si(100) substrates via a sol-gel method. The effects of composition-gradient sequence on the microstructure, dielectric properties, and energy-storage behaviors were investigated in detail. As compared to PLZT films with single composition, the compositionally graded PLZT films displayed significant enhancement in dielectric properties and energy-storage performance. The largest dielectric constant of 2170 at 100 kHz and the largest discharged energy-storage density of 12.4 J/cm3 at 800 kV/cm were achieved in the up-graded multilayer PLZT thick films.

  14. Ferroelectric to relaxor crossover and dielectric phase diagram in the BaTiO3-BaSnO3 system

    Microsoft Academic Search

    C. Lei; A. A. Bokov; Z.-G. Ye

    2007-01-01

    The (1-x)BaTiO3-xBaSnO3 (0<=x=0.04 and at lower temperatures in those with a smaller x. For 0<=x<=xc=0.19, the temperature of the dielectric peak Tm, corresponding to the diffuse transition from the ergodic polar cluster state to the ferroelectric state, decreases with increasing x and does not depend on frequency. The diffuseness of the peak gradually increases. For x>xc, the permittivity exhibits relaxor

  15. Low temperature dielectric dispersion and relaxor like behavior in multiferroic Ba3NbFe3Si2O14

    NASA Astrophysics Data System (ADS)

    Rathore, Satyapal Singh; Mishra, S. K.; Vitta, Satish

    2012-04-01

    The structure and physical properties such as magnetization, heat capacity, and dielectric constant of the polycrystalline Ba3NbFe3Si2O14 have been studied in detail. It is found to be structurally similar to the single crystal and also has a similar antiferromagnetic transition at TN˜26 K. The heat capacity measured in the temperature range 5 K-300 K also shows a single peak at 26 K in agreement with the magnetic behavior. The dielectric constant measured both as a function of temperature and frequency, 10 Hz to 1 MHz however exhibits two clear peaks in the temperature ranges, 20 K-35 K, and 40 K-125 K, which are dispersive in nature. Both the peaks are found to be coupled to the magnetic order with the high temperature peak signaling the onset of magnetic order while the low temperature peak signifies the completion of magnetic order. The dispersion behavior is similar to that observed in relaxor ferroelectrics wherein formation of polar nano-regions affects the relaxation dynamics.

  16. Dielectric properties of material with random off-center defects: Monte Carlo simulation of relaxor ferroelectrics

    Microsoft Academic Search

    C.-C. Su; B. Vugmeister; A. G. Khachaturyan

    2001-01-01

    A Ginzburg-Landau type theory of interaction of randomly distributed local dipoles in a paraelectric crystal is developed. The interaction is caused by the polarization of the host lattice generated by these dipoles. The obtained effective Hamiltonian of the dipole-dipole interaction is employed for the Monte Carlo simulation of ferroelectric properties of a system with off-center dopant ions producing local dipoles.

  17. Pyroelectric energy conversion using PLZT ceramics and the ferroelectricergodic relaxor phase transition

    E-print Network

    Pilon, Laurent

    Pyroelectric energy conversion using PLZT ceramics and the ferroelectric­ergodic relaxor phase conversion using PLZT ceramics and the ferroelectric­ergodic relaxor phase transition Felix Y Lee, Hwan Ryul titanate (PLZT) ceramics undergoing a relaxor­ferroelectric phase transition. The Olsen cycle consists

  18. Variation of Piezoelectric properties and mechanisms across the relaxor-like/Ferroelectric continuum in BiFeO3- (K0.5Bi0.5)TiO3-PbTiO3 ceramics.

    PubMed

    Bennett, James; Shrout, Thomas R; Zhang, Shujun; Owston, Heather E; Stevenson, Tim J; Esat, Faye; Bell, Andrew J; Comyn, T P

    2015-01-01

    1- x - y)BiFeO3-x(K0.5Bi0.5)TiO3-yPbTiO3 (BFKBT- PT) piezoelectric ceramics were investigated across the compositional space and contrasted against the xBiFeO3- (1-x)(K0.5Bi0.5)TiO3 (BF-KBT) system, whereby a range of relaxor-like/ferroelectric behavior was observed. Structural and piezoelectric properties were closely related to the PbTiO3 concentration; below a critical concentration, relaxor-like behavior was identified. The mechanisms governing the piezoelectric behavior were investigated with structural, electrical, and imaging techniques. X-ray diffraction established that longrange non-centrosymmetric crystallographic order was evident above a critical PbTiO3 concentration, y > 0.1125. Commensurate with the structural analysis, electric-field-induced strain responses showed electrostrictive behavior in the PbTiO3-reduced compositions, with increased piezoelectric switching in PbTiO3-rich compositions. Positive-up-negative-down (PUND) analysis was used to confirm electric-field-induced polarization measurements, elucidating that the addition of PbTiO3 increased the switchable polarization and ferroelectric ordering. Piezoresponse force microscopy (PFM) of the BF-KBT-PT system exhibited typical domain patterns above a critical PbTiO3 threshold, with no ferroelectric domains observed in the BF-KBT system in the pseudocubic region. Doping of BiFeO3-PbTiO3 has been unsuccessful in the search for hightemperature materials that offer satisfactory piezoelectric properties; however, this system demonstrates that the partial substitution of alternative end-members can be an effective method. The partial substitution of PbTiO3 into BF-KBT enables long-range non-centrosymmetric crystallographic order, resulting in increased polar order and TC, compared with the pseudocubic region. The search for novel high-temperature piezoelectric ceramics can therefore exploit the accommodating nature of the perovskite family, which allows significant variance in chemical and physical characters in the exploration of new solid-solutions. PMID:25585388

  19. Structural properties of 0.65Pb(Mg1/3Nb2/3)O3-0.35PbTiO3 relaxor ferroelectric thin films on SrRuO3 conducting oxides.

    PubMed

    Lee, Ji Hye; Choi, Mi Ri; Jo, William; Jang, Ji Young; Kim, Mi Young

    2008-09-01

    Coating of 0.65Pb(Mg(1/3)Nb(2/3))O(3)-0.35PbTiO(3) (PMN-PT) relaxor ferroelectrics by a sol-gel method is followed by growth of epitaxial SrRuO(3) (SRO) metallic oxide electrodes on SrTiO(3) (STO) single-crystal substrate by pulsed laser deposition. High-quality PMN-PT films on SRO with preferred growth orientation were successfully fabricated by controlling the operation parameters. Structural properties of relaxor ferroelectric PMN-PT thin films on SRO/STO substrates have been studied by X-ray diffraction (XRD), transmission electron microscopy (TEM) and atomic force microscopy (AFM). In-plane and out-of-plane alignments of the heterostructure are confirmed and the structural twinning of the materials are also revealed. PMID:18547732

  20. Detection of the critical end point in PbSc0.5Ta0.36Nb0.14O3 relaxor ferroelectrics crystals via acoustic emission

    NASA Astrophysics Data System (ADS)

    Dul'kin, E.; Mihailova, B.; Gospodinov, M.; Roth, M.

    2014-09-01

    PbSc0.5Ta0.36Nb0.14O3 relaxor-ferroelectric crystals were studied by the means of dielectric and acoustic emission (AE) methods in the temperature range of 180-300 K. In zero dc electric field (E) no AE was detected at the smeared dielectric maximum Tm ? 260 K characteristic for canonical relaxor ferroelectrics. Under the E a phase transition appears at TC = 217 K for E ˜ 1 kV cm-1. The TC(E) dependence is linear with an anomaly point at E ˜ 1.3 kV cm-1, at which dTC/dE abruptly changes. At this E value the AE rate exhibits a maximum. The anomalous E point is assigned to be the critical end point for this solid solution.

  1. Metamaterials: Novel relaxor and magnetoelectric nanocomposite

    NASA Astrophysics Data System (ADS)

    Maiti, Tanmoy

    In this thesis, we have studied structure-property correlation of the various Ba(ZrxTi1-x)O3 compositions and a new complete phase diagram of Barium Zirconate Titanate, Ba(ZrxTi 1-x)O3 has been developed in the composition range 0?x?1.00. Barium Zirconate Titanate, Ba(ZrxTi1-x)O3 system depending on the composition, successively depicts the properties extending from simple dielectric (pure BaZrO3) to polar cluster dielectric, relaxor ferroelectric, 2nd order like diffuse phase transition, ferroelectric with pinched phase transitions and then to a proper ferroelectric (pure BaTiO3). So far there has been no other single solid solution system that demonstrates all complex aspects of ferroelectricity. Ba(ZrxTi1-x)O3 (BZT) ceramics of the several compositions have been prepared by convention solid state synthesis route. All the BZT compositions were verified to be single phase perovskite by studying the room temperature XRD behavior of these compositions. Dielectric behavior of the BZT ceramics has been studied with and without bias in the temperature range from 300 K to 15 K. The dielectric properties of the material show typical relaxor-like behavior for the BaZrxTi1-xO 3 compositions with 0.25behavior has been observed. In contrary to the classic relaxor ferroelectrics like PMN, PZN etc where intrinsic disorder prevails, in our present investigation we have introduced the disorder gradually through breaking the long range translational symmetry of BaZrO3 by the incorporation of Ti4+ ion in BaZrO 3 lattice to observe the relaxor behavior in a non-ferroelectric material like BaZrO3 with low dielectric constant (<40). From the thermal hysteresis in dielectric behavior and d.c. field dependent dielectric studies it has been concluded that with the incorporation of Ti4+ ion in the BaZrO3 matrix BaZrxTi1-xO3 compositions (x?0.80) start showing polar-cluster like behavior. Beyond an optimum content of polar BaTiO3 in the non polar matrix of BaZrO 3 probably a critical size and distribution density of the polar regions are reached when polar cluster like BaZrxTi1-xO3 ceramics start showing the relaxor-like behavior (x?0.75). This has been further confirmed from the calculation of degree of relaxation (gamma) and Vogel-Fulcher freezing temperature (TVF). To enhance our understanding the relaxor behavior in BaZrxTi1-xO3 ceramics pyroelectric, thermal strain measurements have been carried out from the cryogenic temperature to very high temperature (˜650 K). Powder neutron diffraction measurements have been carried out to determine the structure of the BZT relaxor compositions. Structural analysis of the powder neutron diffraction by Rietveld refinement reveals the global structure of the BZT relaxors as cubic. High q-resolution neutron scattering data has been collected on the BZT relaxor compositions by triple axis spectrometer. However, no such splitting in the Bragg peaks of BZT ceramics has been observed even at 4 K and mirror the results obtained from the powder neutron diffraction data predicting the global structure of BZT relaxors as cubic. The local structure of the BZT ceramics has been investigated by Raman spectra. It is seen from the Raman investigation that local polar regions exist in the BZT ceramics even at 550 K at which temperature both end members of the phase diagram BaZrO3 and BaTiO3 are cubic in pure form. From the detailed investigation on the structure and properties of BaZrxTi1-xO3 compositions it can be said that BZT is an engineered material designed by self-assembled polar nano-regions resulting some unusual properties, which can not be predicted from its constituents BaTiO3 and BaZrO3. Hence BaZrxTi1-xO3 is qualified as meta-materials. Further we have shown that one can engineer a meta-material, which can show dielectric relaxation behavior even none of the constituents of the materials does not show such properties. We have shown a potential approach to fabricate the rel

  2. Broad-Band Dielectric Spectroscopy of Relaxor Ferroelectric Sr0.61Ba0.39Nb2O6

    Microsoft Academic Search

    E. Buixaderas; M. Kempa; S. Veljko; M. Savinov; S. Kamba; J. Petzelt; R. Pankrath

    2005-01-01

    Broad-frequency range dielectric data of strontium barium niobate with 61% of Sr, from kHz to THz range, has been studied using various experimental techniques (FTIR, time-domain THz spectroscopy, HF coaxial technique and standard LF dielectric spectroscopy) in a wide interval of temperatures (20–600 K). Strong dielectric anisotropy was seen by all the experimental methods. Relaxor properties were detected in the

  3. Re-entrant relaxor behavior of Ba{sub 5}RTi{sub 3}Nb{sub 7}O{sub 30} (R = La, Nd, Sm) tungsten bronze ceramics

    SciTech Connect

    Li, Kun; Li Zhu, Xiao; Qiang Liu, Xiao; Ming Chen, Xiang [Department of Materials Science and Engineering, Zhejiang University, 38 Zheda Road, Hangzhou 310027 (China)] [Department of Materials Science and Engineering, Zhejiang University, 38 Zheda Road, Hangzhou 310027 (China)

    2013-03-18

    Ba{sub 5}RTi{sub 3}Nb{sub 7}O{sub 30} (R = La, Nd, Sm) tungsten bronze ceramics were prepared, and the dielectric and ferroelectric properties were investigated over a broad temperature range. The relaxor nature was determined for all compositions in their permittivity curves, and a second anomaly of the dielectric loss (tan {delta}) was observed around 250 K in Ba{sub 5}NdTi{sub 3}Nb{sub 7}O{sub 30} and around 275 K in Ba{sub 5}SmTi{sub 3}Nb{sub 7}O{sub 30}. Both the maximum and remanent polarization tended to decrease and vanish at low temperatures in the ferroelectric phase for all compositions, which was referred to as the low temperature re-entrant relaxor behavior. The remanent polarization increased with decreasing temperature first and then reached the maximum value at the re-entrant temperature (T{sub r}). For Ba{sub 5}RTi{sub 3}Nb{sub 7}O{sub 30} (R = La, Nd, Sm), T{sub r} decreased with the radius of R{sup 3+} cations and the applied field amplitude.

  4. Significant enhancement of energy-storage performance of (Pb0.91La0.09)(Zr0.65Ti0.35)O3 relaxor ferroelectric thin films by Mn doping

    NASA Astrophysics Data System (ADS)

    Liu, Yunying; Hao, Xihong; An, Shengli

    2013-11-01

    1.5-?m-thick (Pb0.91La0.09)(Zr0.65Ti0.35)O3 (PLZT) relaxor ferroelectric (RFE) films doped by Mn from 0 to 5 mol. % were deposited on LaNiO3/Si(100) substrates via a sol-gel method. The microstructure, dielectric properties, and energy-storage performance of PLZT thin films were investigated as a function of Mn content. X-ray diffraction patterns and scanning electron microscopy indicated that all the films possessed a similar microstructure with pure perovskite phase. However, the dielectric constant, average breakdown fields, and the difference between maximum polarization and remnant polarization of the films were improved by Mn doping. A giant recoverable energy-storage density of 30.8 J/cm3 was obtained in 1 mol. % Mn-doped films. Moreover, good temperature-dependent energy-storage stability was also observed in the films. These results indicated that Mn-doping was an efficient way to optimize the energy-storage behaviors of PLZT RFE films.

  5. Critical Property in Relaxor-PbTiO(3) Single Crystals --- Shear Piezoelectric Response.

    PubMed

    Li, Fei; Zhang, Shujun; Xu, Zhuo; Wei, Xiaoyong; Shrout, Thomas R

    2011-06-01

    The shear piezoelectric behavior in relaxor-PbTiO(3) (PT) single crystals is investigated in regard to crystal phase. High levels of shear piezoelectric activity, d(15) or d(24) >2000 pC N(-1), has been observed for single domain rhombohedral (R), orthorhombic (O) and tetragonal (T) relaxor-PT crystals. The high piezoelectric response is attributed to a flattening of the Gibbs free energy at compositions proximate to the morphotropic phase boundaries, where the polarization rotation is easy with applying perpendicular electric field. The shear piezoelectric behavior of pervoskite ferroelectric crystals was discussed with respect to ferroelectric-ferroelectric phase transitions and dc bias field using phenomenological approach. The relationship between single domain shear piezoelectric response and piezoelectric activities in domain engineered configurations were given in this paper. From an application viewpoint, the temperature and ac field drive stability for shear piezoelectric responses are investigated. A temperature independent shear piezoelectric response (d(24), in the range of -50°C to O-T phase transition temperature) is thermodynamically expected and experimentally confirmed in orthorhombic relaxor-PT crystals; relatively high ac field drive stability (5 kV cm(-1)) is obtained in manganese modified relaxor-PT crystals. For all thickness shear vibration modes, the mechanical quality factor Qs are less than 50, corresponding to the facilitated polarization rotation. PMID:21960942

  6. Critical Property in Relaxor-PbTiO3 Single Crystals --- Shear Piezoelectric Response

    PubMed Central

    Xu, Zhuo; Wei, Xiaoyong; Shrout, Thomas R.

    2011-01-01

    The shear piezoelectric behavior in relaxor-PbTiO3 (PT) single crystals is investigated in regard to crystal phase. High levels of shear piezoelectric activity, d15 or d24 >2000 pC N?1, has been observed for single domain rhombohedral (R), orthorhombic (O) and tetragonal (T) relaxor-PT crystals. The high piezoelectric response is attributed to a flattening of the Gibbs free energy at compositions proximate to the morphotropic phase boundaries, where the polarization rotation is easy with applying perpendicular electric field. The shear piezoelectric behavior of pervoskite ferroelectric crystals was discussed with respect to ferroelectric-ferroelectric phase transitions and dc bias field using phenomenological approach. The relationship between single domain shear piezoelectric response and piezoelectric activities in domain engineered configurations were given in this paper. From an application viewpoint, the temperature and ac field drive stability for shear piezoelectric responses are investigated. A temperature independent shear piezoelectric response (d24, in the range of ?50°C to O-T phase transition temperature) is thermodynamically expected and experimentally confirmed in orthorhombic relaxor-PT crystals; relatively high ac field drive stability (5 kV cm?1) is obtained in manganese modified relaxor-PT crystals. For all thickness shear vibration modes, the mechanical quality factor Qs are less than 50, corresponding to the facilitated polarization rotation. PMID:21960942

  7. Role of random electric fields in relaxors.

    PubMed

    Phelan, Daniel; Stock, Christopher; Rodriguez-Rivera, Jose A; Chi, Songxue; Leão, Juscelino; Long, Xifa; Xie, Yujuan; Bokov, Alexei A; Ye, Zuo-Guang; Ganesh, Panchapakesan; Gehring, Peter M

    2014-02-01

    PbZr(1-x)Ti(x)O3 (PZT) and Pb(Mg1/3Nb2/3)(1-x)Ti(x)O3 (PMN-xPT) are complex lead-oxide perovskites that display exceptional piezoelectric properties for pseudorhombohedral compositions near a tetragonal phase boundary. In PZT these compositions are ferroelectrics, but in PMN-xPT they are relaxors because the dielectric permittivity is frequency dependent and exhibits non-Arrhenius behavior. We show that the nanoscale structure unique to PMN-xPT and other lead-oxide perovskite relaxors is absent in PZT and correlates with a greater than 100% enhancement of the longitudinal piezoelectric coefficient in PMN-xPT relative to that in PZT. By comparing dielectric, structural, lattice dynamical, and piezoelectric measurements on PZT and PMN-xPT, two nearly identical compounds that represent weak and strong random electric field limits, we show that quenched (static) random fields establish the relaxor phase and identify the order parameter. PMID:24449912

  8. Role of random electric fields in relaxors

    PubMed Central

    Phelan, Daniel; Stock, Christopher; Rodriguez-Rivera, Jose A.; Chi, Songxue; Leão, Juscelino; Long, Xifa; Xie, Yujuan; Bokov, Alexei A.; Ye, Zuo-Guang; Ganesh, Panchapakesan; Gehring, Peter M.

    2014-01-01

    PbZr1–xTixO3 (PZT) and Pb(Mg1/3Nb2/3)1–xTixO3 (PMN-xPT) are complex lead-oxide perovskites that display exceptional piezoelectric properties for pseudorhombohedral compositions near a tetragonal phase boundary. In PZT these compositions are ferroelectrics, but in PMN-xPT they are relaxors because the dielectric permittivity is frequency dependent and exhibits non-Arrhenius behavior. We show that the nanoscale structure unique to PMN-xPT and other lead-oxide perovskite relaxors is absent in PZT and correlates with a greater than 100% enhancement of the longitudinal piezoelectric coefficient in PMN-xPT relative to that in PZT. By comparing dielectric, structural, lattice dynamical, and piezoelectric measurements on PZT and PMN-xPT, two nearly identical compounds that represent weak and strong random electric field limits, we show that quenched (static) random fields establish the relaxor phase and identify the order parameter. PMID:24449912

  9. Large Energy Storage Density and High Thermal Stability in a Highly Textured (111)-Oriented Pb0.8Ba0.2ZrO3 Relaxor Thin Film with the Coexistence of Antiferroelectric and Ferroelectric Phases.

    PubMed

    Peng, Biaolin; Zhang, Qi; Li, Xing; Sun, Tieyu; Fan, Huiqing; Ke, Shanming; Ye, Mao; Wang, Yu; Lu, Wei; Niu, Hanben; Zeng, Xierong; Huang, Haitao

    2015-06-24

    A highly textured (111)-oriented Pb0.8Ba0.2ZrO3 (PBZ) relaxor thin film with the coexistence of antiferroelectric (AFE) and ferroelectric (FE) phases was prepared on a Pt/TiOx/SiO2/Si(100) substrate by using a sol-gel method. A large recoverable energy storage density of 40.18 J/cm(3) along with an efficiency of 64.1% was achieved at room temperature. Over a wide temperature range of 250 K (from room temperature to 523 K), the variation of the energy density is within 5%, indicating a high thermal stability. The high energy storage performance was endowed by a large dielectric breakdown strength, great relaxor dispersion, highly textured orientation, and the coexistence of FE and AFE phases. The PBZ thin film is believed to be an attractive material for applications in energy storage systems over a wide temperature range. PMID:25996244

  10. Large enhancement of the recoverable energy storage density and piezoelectric response in relaxor-ferroelectric capacitors by utilizing the seeding layers engineering

    NASA Astrophysics Data System (ADS)

    Xie, Zhenkun; Yue, Zhenxing; Peng, Bin; Zhang, Jie; Zhao, Chuan; Zhang, Xiaohua; Ruehl, Griffin; Li, Longtu

    2015-05-01

    In this work, we demonstrate an approach to improve the recoverable energy-storage performance and piezoelectric response of 0.4Bi(Ni1/2Zr1/2)O3-0.6PbTiO3 (BNZ-PT) relaxor-ferroelectric film capacitors by utilizing the seeding layers engineering. Highly (100)-oriented BNZ-PT films were prepared through alternatively introducing PbO seeding layers, and the effects of PbO seeds on microstructure and electrical properties were investigated in details. Compared to the films without seeds, the PbO-seeded BNZ-PT films exhibit significant enhancement in dielectric and piezoelectric properties as well as energy-storage performance. The maximum energy-storage density of 56.1 ± 2.4 J/cm3 and a piezoelectric coefficient as high as 125 ± 10 pm/V have been achieved in the highly (100)-oriented BNZ-PT films at 2167 kV/cm, which are increased by 40.6% and 50.6% compared to the films without seeds, respectively. The observed tremendous enhancement of energy-storage performance and piezoelectric response can be attributed to the better crystallization quality and higher degree of (100)-preferred orientation in the films which would motivate higher domain-wall mobility.

  11. Nonlinear electric–mechanical behavior and micromechanics modelling of ferroelectric domain evolution

    Microsoft Academic Search

    W. Lu; D.-N. Fang; C. Q. Li; K.-C. Hwang

    1999-01-01

    Domains exist in ferroelectric ceramics. External loads, such as electric field and stress, can cause domain switching. Domain switching always results in nonlinear ferroelectricity and ferroelasticity of ferroelectric ceramics. In this investigation, nonlinear electric–mechanical behavior related to ferroelectric and ferroelastic domain switching is experimentally and theoretically studied. In the experimental work, the electric–mechanical response of a soft PZT ferroelectric ceramic

  12. Relaxor ferroelectricity in strained epitaxial SrTiO3 thin films on DyScO3 substrates

    Microsoft Academic Search

    M. D. Biegalski; Y. Jia; D. G. Schlom; S. Trolier-McKinstry; S. K. Streiffer; V. Sherman; R. Uecker; P. Reiche

    2006-01-01

    The ferroelectric properties of 500 A˚ thick strained, epitaxial SrTiO3 films grown on DyScO3 substrates by reactive molecular-beam epitaxy are reported. Despite the near 1% biaxial tensile strain, the x-ray rocking curve full widths at half maximum in omega are as narrow as 7 arc sec (0.002°). The films show a frequency-dependent permittivity maximum near 250 K that is well

  13. Feature article Novel polymer ferroelectric behavior via crystal isomorphism and the

    E-print Network

    Taylor, Philip L.

    ] behavior in ceramics, RFE and double-hysteresis-loop (DHL) behavior in crystalline ferroelectric polymers behavior is observed. Obviously, the physics for ferroelectric polymers is different from that for ceramics nonlinear dielectric properties Different from ceramic ferroelectrics, ferroelectric (FE) polymers represent

  14. The dielectric behavior of polycrystalline ferroelectric films with fiber textures

    E-print Network

    Li, Jiangyu

    The dielectric behavior of polycrystalline ferroelectric films with fiber textures Quangen Du of crystallographic symmetry, texture, and internal strain on the dielectric properties of polycrystalline ferroelec- tric thin films with fiber textures, including spontaneous polarization, coercivity, dielectric

  15. Investigation of the multiscale constitutive behavior of ferroelectric materials using advanced diffraction techniques

    Microsoft Academic Search

    Robert C. Rogan

    2004-01-01

    Ferroelectric ceramics are widely used in a diverse set of devices including sensors, actuators, and transducers. The technological importance of ferroelectrics originates from their large electromechanical coupling. Ferroelectric materials exhibit a complicated behavior in response to both electrical and mechanical loads which produce large internal stresses that eventually lead to failure. Efforts to model and predict the behavior of ferroelectrics

  16. Electric-field-induced local structural phenomena in relaxor ferroelectric PbSc(0.5)Nb(0.5)O3 near the intermediate temperature T* studied by Raman spectroscopy.

    PubMed

    Steilmann, T; Maier, B J; Gospodinov, M; Bismayer, U; Mihailova, B

    2014-04-30

    Raman spectroscopy at different temperatures and under an external electric field E was applied to PbSc0.5Nb0.5O3 single crystals in order to gain further insights into the mesoscopic-scale coupling processes in perovskite-type (ABO3) relaxor ferroelectrics. Parallel and cross-polarized Raman spectra were collected between 800-80?K with E applied along the cubic [1?0?0], [1?1?0] or [1?1?1] crystallographic directions. The analysis was focused on the field-induced changes in the temperature evolution of three low-energy phonon modes: the Pb-localized mode near 50?cm(-1), the Pb-BO3 translation mode near 150?cm(-1), and the B-cation-localized mode near 250?cm(-1). The results show that competitive ferroelectric (FE) and antiferroelectric (AFE) coupling exists within the system of off-centred Pb(2+) cations, within the system of off-centred B-site cations as well as between off-centred Pb(2+) and B-site cations. The strong AFE-type coupling between Pb(2+) cations along the cubic body diagonal significantly influences the coupling between the B-site cations via the Pb-BO3 mode and results in AFE-type behaviour of the 'microscopic' T* determined from the B-cation-localized mode near 250?cm(-1), which explains the previously reported non-trivial field dependence of the 'macroscopic' characteristic temperatures: the temperature of the dielectric-permittivity maximum Tm, T*, and the Burns temperature TB. The comparative analysis between PbSc0.5Nb0.5O3 and PbSc0.5Ta0.5O3 indicates that two major displacive order parameters couple to form a relaxor state in B-site complex perovskites: the FE order associated with polar shifts of B-site cations and the AFE order associated with polar shifts of A-site cations. The latter penetrates through both polar and non-polar regions, but it is highly frustrated due to the high density of translation-symmetry faults in the chemical NaCl-type B-site order. The frustrated AFE order of off-centred A-site cations might be the key factor for the existence of a relaxor state. PMID:24722533

  17. The extrinsic nature of nonlinear behavior observed in lead zirconate titanate ferroelectric ceramic

    E-print Network

    Cao, Wenwu

    . This lossy nature suggests that the nonlinearities in a ferroelectric ceramic are generated by the domain of nonlinearity) all indicate the extrinsic nature of the nonlinear behavior of ferroelectric ceramics behavior of piezoceramic materials is very important because ferroelectric ceramics are now widely used

  18. Effect of electric fields on fracture behavior of ferroelectric ceramics

    Microsoft Academic Search

    H. G Beom; S. N Atluri

    2003-01-01

    The asymptotic problem of a semi-infinite crack perpendicular to the poling direction in a ferroelectric ceramic subjected to combined electric and mechanical loading is analyzed to investigate effect of electric fields on fracture behavior. Electromechanical coupling induced by the piezoelectric effect is neglected in this paper. The shape and size of the switching zone is shown to depend strongly on

  19. Acoustic evidence of distinctive temperatures in relaxor-multiferroics

    NASA Astrophysics Data System (ADS)

    Smirnova, E.; Sotnikov, A.; Ktitorov, S.; Zaitseva, N.; Schmidt, H.; Weihnacht, M.

    2014-02-01

    We present an acoustic study of relaxor ferroelectrics with magnetic ordering PbFexB1-xO3 (B = Nb, Ta, W) in the wide temperature range from 100 to 750 K as well as relaxor PbMg1/3Nb2/3O3 at temperatures from 300 to 750 K. The longitudinal and transverse acoustic wave velocity and attenuation have been measured by the ultrasonic pulse-echo technique at frequencies of 5 and 10 MHz. The strong anomalies observed in the longitudinal sound velocity and attenuation versus temperature are correlated with a temperature range of the coexistence of relaxor ferroelectric and antiferromagnetic states. Attenuation peaks have been observed at distinctive temperatures for relaxors, i.e., at TB (Burns temperature) and T* (an additional distinctive temperature). Fluctuations of the polar nanoregion boundaries are considered as the source of the acoustic anomalies.

  20. Composition dependence of the diffuse scattering in the relaxor ferroelectric compound (1-x)Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}-xPbTiO{sub 3} (0{<=}x{<=}0.40)

    SciTech Connect

    Matsuura, M.; Hirota, K. [Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581 (Japan); Gehring, P. M. [NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8562 (United States); Ye, Z.-G.; Chen, W. [Department of Chemistry, Simon Fraser University, Burnaby, British Columbia, V5A 1S6 (Canada); Shirane, G. [Department of Physics, Brookhaven National Laboratory, Upton, New York 11973-5000 (United States)

    2006-10-01

    We have used neutron diffraction to characterize the diffuse scattering in five single crystals of the relaxor ferroelectric (1-x)Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}-xPbTiO{sub 3} (PMN-xPT) with x=0, 10, 20, 30, and 40%. The addition of ferroelectric PbTiO{sub 3} modifies the well-known 'butterfly' and 'ellipsoidal' diffuse scattering patterns observed in pure PMN (x=0), which are believed to be associated with the presence of randomly oriented polar nanoregions. In particular, the anisotropy of the diffuse scattering diminishes as the PT content increases. The spatial correlation length {xi} along the [110] direction derived from the width of the diffuse scattering at room temperature increases from 12.6 A for PMN to 350 A for PMN-20%PT. In addition, the diffuse scattering intensity at q=0 grows and reaches a maximum value around the morphotropic phase boundary (MPB), which suggests that it is proportional to the dielectric susceptibility. Beyond x=30%, a concentration very close to the MPB, no diffuse scattering is observed below T{sub C}, and well-defined critical behavior appears near T{sub C}. By contrast, the diffuse scattering for x{<=}20% persists down to low temperatures, where the system retains an average cubic structure (T{sub C}=0). Finally, the anisotropic soft transverse optic (TO) modes observed in PMN are found to be isotropic for PMN-30%PT, which strongly suggests a connection between the anisotropic diffuse scattering and the TO modes.

  1. Unconventional resistive switching behavior in ferroelectric tunnel junctions.

    PubMed

    Mao, H J; Song, C; Xiao, L R; Gao, S; Cui, B; Peng, J J; Li, F; Pan, F

    2015-04-21

    We investigate an unconventional resistive switching (RS) behavior in La0.67Sr0.33MnO3/BaTiO3/metal (LSMO/BTO) ferroelectric tunnel junctions (FTJs), which is dominated by the variation of the barrier potential profile modulated by the migration of oxygen vacancies in the p-LSMO/n-BTO junction. The LSMO/BTO/Co junction exhibits a remarkable self-rectifying effect ascribed to the high-density interface state at the BTO/Co interface, in contrast to the symmetric conductivity when the top metal electrode is inert Pt. The effects of ferroelectric polarization on the RS behavior are also emphasized. Our work builds a bridge between FTJs and resistive random access memory devices. PMID:25789877

  2. Structure-property-performance relationships of new high temperature relaxors for capacitor applications

    NASA Astrophysics Data System (ADS)

    Stringer, Craig J.

    This thesis extends the investigations on perovskite solid solutions based on PbTiO3-Bi(Me',Me")O3 (Me' = Sc3+, Zn2+, Mg2+, Ni2+, In3+ , Fe3+, etc. and Me" = Ti4+, Nb 5+, W6+) systems. The ferroelectric transition temperature (TC) behavior was considered in the tetragonal phase region of the PbTiO 3-Bi(Me',Me")O3 systems. Trends in the TC compositional dependence exhibited three main cases: case 1, a continued increase in transition temperature above the end-member PbTiO3 (495°C); case 2, an increase and then decrease of the transition temperature; and case 3, a continuous decrease in the transition temperature with Bi(Me',Me")O 3 additions. New relaxor materials were developed from the PbTiO3-Bi(Me',Me")O 3 solid solutions; specifically, the Bi(Mg3/4W1/4)O 3-PbTiO3 (BMW-PT) binary solid solution and BiScO3-Pb(Mg 1/3Nb2/3)O3-PbTiO3 (BS-PMN-PT) ternary solid solution were investigated. Permittivity, polarization and pyroelectric measurements were performed on BMW-PT and BS-PMN-PT compositions with respect to temperature with characteristic relaxor behavior observed. The complex solid solution BMW-PT exhibited a morphotropic phase boundary at ˜48 mol% PbTiO3 with a corresponding TC of 205°C. On further structural analysis with diffraction contrast transmission electron microscopy along with x-ray diffraction, evidence of B-site ordering was observed. The BS-PMN-PT proved to be a model system with high temperature relaxor properties of Tmax ˜ 250°C to 300°C and ?max ˜ 14,000 to 17,000 at 1 kHz. The deviation temperature, TD, or temperature of the onset of local spontaneous polarization, was determined by thermal strain measurement and high temperature dielectric measurement to be approximately 600°C; up to 250°C higher than any reported value for relaxor ferroelectrics. The frequency dependence of the temperature of the permittivity maximum was found to follow the Vogel-Fulcher relationship, with an activation energy (EA) of ˜0.1 eV, and a freezing temperature (Tf) of ˜150°C. Static and in-situ transmission electron microscopy investigations of the BS-PMN-PT compositions demonstrated a frustrated microstructure of nanometer scale regions and were used to establish structure-property relationships with different electric field and thermal histories. A comparative study of the key relaxor parameters, EA, T f, and TD was tabulated with previously investigated relaxor ferroelectrics. These parameters were found to scale relative to other lead-based perovskite relaxor ferroelectric compounds and solid solutions, with the BS-PMN-PT ternary system exhibiting the highest temperature behavior. Finally, to demonstrate one possible application area for these materials, multilayer ceramic capacitor devices were designed for operation at 300°C and up to 10 kHz. The voltage saturation was found to be extremely encouraging at 300°C with observed changes in capacitance (˜3%) on the application of 10 kV/cm. The insulation resistivity followed an Arrhenius behavior and at 300°C was ˜1010 O-cm. Weibull statistics were used to estimate a characteristic breakdown field at 300°C for the BS-PMN-PT multilayer capacitors of ˜40 kV/cm. Current-voltage measurements were performed to voltages up to breakdown and exhibited Ohmic behavior, indicating intrinsically controlled conduction. Highly accelerated life time tests were performed on BS-PMN-PT capacitors. It was observed that silver migration from termination electrodes caused premature failure at elevated temperature.

  3. Electric field cycling behavior of ferroelectric hafnium oxide.

    PubMed

    Schenk, Tony; Schroeder, Uwe; Peši?, Milan; Popovici, Mihaela; Pershin, Yuriy V; Mikolajick, Thomas

    2014-11-26

    HfO2 based ferroelectrics are lead-free, simple binary oxides with nonperovskite structure and low permittivity. They just recently started attracting attention of theoretical groups in the fields of ferroelectric memories and electrostatic supercapacitors. A modified approach of harmonic analysis is introduced for temperature-dependent studies of the field cycling behavior and the underlying defect mechanisms. Activation energies for wake-up and fatigue are extracted. Notably, all values are about 100 meV, which is 1 order of magnitude lower than for conventional ferroelectrics like lead zirconate titanate (PZT). This difference is mainly atttributed to the one to two orders of magnitude higher electric fields used for cycling and to the different surface to volume ratios between the 10 nm thin films in this study and the bulk samples of former measurements or simulations. Moreover, a new, analog-like split-up effect of switching peaks by field cycling is discovered and is explained by a network model based on memcapacitive behavior as a result of defect redistribution. PMID:25365475

  4. Temperature characteristics and development of field-induced phase transition in relaxor ferroelectric Pb(Mg{sub 1/3}Nb{sub 2/3}){sub 0.87}Ti{sub 0.13}O{sub 3} ceramics

    SciTech Connect

    Peraentie, J.; Hagberg, J.; Uusimaeki, A.; Jantunen, H. [Microelectronics and Materials Physics Laboratories and EMPART Research Group of Infotech Oulu, University of Oulu, P.O. Box 4500, FIN-90014 Oulu (Finland)

    2008-09-29

    Ferroelectric phase inducing threshold electric field E{sub th} and its temperature dependence were determined in relaxor ferroelectric 0.87Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}-0.13PbTiO{sub 3} (PMN-13PT) ceramics by measuring dielectric response on a dc field pulse. Evolution of the induced ferroelectricity was observed by means of polarization measurements. An inducing threshold field was found to have a minimum of E{sub th,min}=1.55 kV/cm at T=-5 deg. C. In contrast to pure PMN, which shows a minimum threshold field near the depolarization temperature, the temperature of the minimum threshold field differs by an amount of {delta}T=23 deg. C from the depolarization temperature T{sub dp}=18 deg. C in PMN-13PT.

  5. Continuous cross-over from ferroelectric to relaxor state and piezoelectric properties of BaTiO{sub 3}-BaZrO{sub 3}-CaTiO{sub 3} single crystals

    SciTech Connect

    Benabdallah, F.; Veber, P., E-mail: veber@icmcb-bordeaux.cnrs.fr; Prakasam, M.; Viraphong, O.; Maglione, M. [CNRS, ICMCB, UPR 9048, F-33600 Pessac (France); Université Bordeaux, ICMCB, UPR 9048, F-33600 Pessac (France); Shimamura, K. [National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan)

    2014-04-14

    Optimal properties like piezoelectricity can be found in polarizable materials for which the structure changes sharply under small composition variations in the vicinity of their morphotropic phase boundary or the triple point in their isobaric temperature-composition phase diagram. In the latter, lead-free (Ba{sub 0.850}Ca{sub 0.150})(Ti{sub 0.900}Zr{sub 0.100})O{sub 3} ceramics exhibit outstanding piezoelectric coefficients. For the first time, we report the growth of piezoelectric lead-free single crystals in the BaTiO{sub 3}-BaZrO{sub 3}-CaTiO{sub 3} pseudo-ternary system. The stoichiometry control in the CaO-BaO-TiO{sub 2}-ZrO{sub 2} solid solution led to single crystals with various compositions ranging from (Ba{sub 0.857}Ca{sub 0.143})(Ti{sub 0.928}Zr{sub 0.072})O{sub 3} to (Ba{sub 0.953}Ca{sub 0.047})(Ti{sub 0.427}Zr{sub 0.573})O{sub 3}. We evidenced a continuous cross-over from a ferroelectric state at high titanium content to a relaxor one on increasing the zirconium content. Such a property tuning is rather seldom observed in lead-free ferroelectrics and confirms what was already reported for ceramics. Single crystal with (Ba{sub 0.838}Ca{sub 0.162})(Ti{sub 0.854}Zr{sub 0.146})O{sub 3} composition, which has been grown and oriented along [001] crystallographic direction, displayed electromechanical coefficients d{sub 31} and k{sub 31} of 93 pC.N{sup ?1} and 0.18, respectively, near the room temperature (T?=?305?K)

  6. Relaxor fluorinated polymers: novel applications and recent developments

    NASA Astrophysics Data System (ADS)

    Bauer, François; Dos Santos, Domingues; Zhang, Qiming

    2011-04-01

    It has been found that by introducing defects into the P(VDF-TrFE) copolymers, it is possible to convert the polymer from a normal ferroelectric to a relaxor ferroelectric. A new class of ferroelectric polymers, i.e., the terpolymers of P(VDF-TrFE-CFE) or of P(VDF-TrFE-CTFE), was developed from the normal ferroelectric PVDF-TrFE polymer by employing proper defect modifications which eliminate detrimental effects associated with a normal first order F-P transition while maintaining high material responses. Relevant studies show that this class of electroactive polymers offers unique properties in comparison with other ferroelectric polymers. The syntheses of these relaxor ferroelectric polymers have been done by a combination of the suspension polymerization process and an oxygen-activated initiator at a temperature of 40 °C. Films from cast solution can be made in different length and thicknesses. Stretching of these films increases the performance as well as the mechanical properties. These relaxor-ferroelectric terpolymers P(VDF-TrFE-CFE), P(VDF-TrFE-CTFE) are multifunctional i.e. electrostrictive material, dielectric for electric energy storage. The terpolymer exhibits high electrostrictive strain (>7%) with relatively high modulus (>0.4GPa). Examples of devices applications using unimorphe systems are presented. Micropump and Optical device concerning a liquid-filled varifocal lens on a chip are described.

  7. Local probing of relaxation time distributions in ferroelectric polymer nanomesas: Time-resolved piezoresponse force spectroscopy and spectroscopic imaging

    SciTech Connect

    Rodriguez, Brian [University College, Dublin] [University College, Dublin; Jesse, Stephen [ORNL] [ORNL; Kim, J. [University of Nebraska, Lincoln] [University of Nebraska, Lincoln; Ducharme, S. [University of Nebraska, Lincoln] [University of Nebraska, Lincoln; Kalinin, Sergei [Oak Ridge National Laboratory (ORNL)] [Oak Ridge National Laboratory (ORNL)

    2008-01-01

    Time-resolved piezoresponse force spectroscopy (TR-PFS) and spectroscopic imaging are developed to probe the spatial variability of relaxation behavior in nanoscale ferroelectric materials and structures. TR-PFS was applied to study polarization dynamics in polyvinylidine fluoride and trifluoroethylene nanomesas. We demonstrate that polarization relaxation in ferroelectric polymers is slow even on the 10 nm length scale of piezoresponse force microscopy (PFM) signal generation. Furthermore, the relaxation times are found to be nonuniform within the nanomesa, indicative of a complex internal structure. The applicability of TR-PFM for studies of polarization dynamics in ferroelectric polymers and relaxors is discussed.

  8. Dielectric response of the relaxor ferroelectric Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3} in the nonergodic state after a DC electric field is turned off

    SciTech Connect

    Kolpakova, N. N. [Russian Academy of Sciences, Ioffe Physicotechnical Institute (Russian Federation)], E-mail: kolpakova@mail.ioffe.ru; Czarnecki, P. [A. Mickiewicz University, Institute of Physics (Poland)

    2006-06-15

    The Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3} (PMN) relaxor system is used as an example to analyze the temperature dependences of the low-frequency dielectric permitivity ({epsilon}'(T)) measured during zero-field heating (ZFH) from T = 10 K to T = 300 K after using different field cooling (FC) conditions. No changes in the temperature dependences of the permittivity have been detected during the transition from a nonergodic relaxor state (NERS) into an ergodic relaxor state (ERS) (at T{sub f} {approx} 216 K). However, the difference {delta}{epsilon}'(T) between the curves corresponding to different field cooling conditions in the same electric field has different shapes and different values below and above T {sup {yields}} (T{sub f} + 9 K){sup -} (for E{sub dc} = 1.52 kV/cm). The reduced permittivities {epsilon}'{sub r}(T, f) recorded under different cooling conditions are shown to change their behavior when passing through T = T{sub f} + 9 K. In NERS, these curves diverge: the stronger the field (0 {<=} E{sub dc} {<=} 3 kV/cm), the larger the divergence. In ERS, however, the {epsilon}'{sub r}(T, f) curves coincide under different cooling conditions irrespective of the field. The character of the changes in {delta}{epsilon}'(T) and {epsilon}'{sub r} (T, f) during the NERS-ERS transition is frequency-independent. The difference in the behavior of the dielectric response during ZFH after cooling in different (ZFC, FC) modes (even in a weak field), for both transition through T{sub f} and cooling down to T = 10 K, indicates different NERSs forming under these conditions. The contribution to {epsilon}'(T) from slowly relaxing regions ({omega} {approx} 0.1 mHz), whose polarization is reoriented after the field is turned off, is responsible for the fact that, during the NERS-ERS transition, the {epsilon}'{sub r}(T, f) curves coincide at a temperature that is higher than T = T{sub f}.

  9. Temperature independent shear piezoelectric response in relaxor-PbTiO3 based crystals

    PubMed Central

    Li, Fei; Zhang, Shujun; Xu, Zhuo; Wei, Xiaoyong; Luo, Jun; Shrout, Thomas R.

    2010-01-01

    The temperature dependence of the shear piezoelectric responses in relaxor-PbTiO3 based perovskite crystals with rhombohedral, orthorhombic, and tetragonal phases were investigated. Based on thermodynamic analysis, high shear piezoelectric coefficients (d24) and good thermal stability were predicted in orthorhombic crystals, owing to the “vertical” orthorhombic-rhombohedral phase boundary. By resonance measurements, shear piezoelectric coefficient d24 was found to be on the order of ?2100 pC?N at room temperature, maintaining same value over the temperature range of ?50–100 °C. In contrast, the shear piezoelectric coefficients d15, with values of 3300, 3600, and 2000 pC?N at room temperature for rhombohedral, orthorhombic, and tetragonal crystals, respectively, exhibited strong temperature dependent behavior due to their respective ferroelectric-ferroelectric phase transitions. PMID:21245942

  10. Microstructural effects on the dielectric and electromechanical properties of lead magnesium(1\\/3)niobium(2\\/3)oxygen(3) relaxor ferroelectrics

    Microsoft Academic Search

    Metin Koyuncu

    2000-01-01

    One of the major concerns with the electrostrictive PbMg1\\/3Nb 2\\/3O3 (PMN) based materials is the formation of a stable non-ferroelectric second phase in small amounts. One objective of this project is to clear the reason behind its formation and consistently achieve 100% pure perovskite phase using the columbite route. Second objective is to develop a model to understand the effect

  11. Introduction Strontium Barium Niobate k-Space Spectroscopy Results Conclusions Unraveling Relaxor Phase Transitions by

    E-print Network

    Osnabrück, Universität

    Introduction Strontium Barium Niobate k-Space Spectroscopy Results Conclusions Unraveling Relaxor 2009 WILLIAMSBURG WORKSHOP ON FUNDAMENTAL PHYSICS OF FERROELECTRICS #12;Introduction Strontium Barium ferroelectrics Introduction Strontium Barium Niobate k-Space Spectroscopy Results Conclusions SBN ­ SrxBa1-xNb2O6

  12. Fano resonance and dipolar relaxation in lead-free relaxors

    NASA Astrophysics Data System (ADS)

    Wang, D.; Hlinka, J.; Bokov, A. A.; Ye, Z.-G.; Ondrejkovic, P.; Petzelt, J.; Bellaiche, L.

    2014-11-01

    Fano resonance is a phenomenon in which a discrete state interferes with a continuum of states and has been observed in many areas of science. Here, we report on the prediction of a Fano resonance in ferroelectric relaxors, whose properties are poorly understood: an ab initio molecular dynamic scheme reveals such resonance between the bare optical phonon mode of the Zr sublattice (the discrete state) and the bare optical phonon mode of the Ti sublattice (the continuum of states) in disordered lead-free Ba(Zr,Ti)O3. The microscopic origins of the discrete state and continuum of states are discussed in the context of relaxor properties. Furthermore, our simulations suggest that the T* characteristic temperature of relaxor is related to a hardening of the vibrational frequencies associated with fluctuation of the Ti sublattice. Finally, a terahertz relaxation mode reflecting reorientations of Ti dipoles and showing a thermally activated behaviour is predicted, in agreement with previous experiments.

  13. A-site doping-induced renormalization of structural transformations in the PbSc{sub 0.5}Nb{sub 0.5}O{sub 3} relaxor ferroelectric under high pressure

    SciTech Connect

    Maier, B. J.; Welsch, A.-M.; Mihailova, B.; Paulmann, C.; Bismayer, U. [Department Geowissenschaften, Universitaet Hamburg, Grindelallee 48, D-20146 Hamburg (Germany); Angel, R. J.; Zhao, J. [Virginia Tech Crystallography Laboratory, Department of Geosciences, Virginia Tech, Blacksburg, Virginia 24060 (United States); Engel, J. M. [Institut fuer Werkstoffwissenschaften, Technische Universitaet Dresden, Helmholtzstr. 7, D-01069 Dresden (Germany); Schmitt, L. A. [Materials Science Structure Research, Universitaet Darmstadt, Petersenstr. 23, D-64287 Darmstadt (Germany); Gospodinov, M. [Institute of Solid State Physics, Bulgarian Academy of Sciences, Boulevard Tzarigradsko Chausse 72, 1784 Sofia (Bulgaria); Friedrich, A. [Institut fuer Geowissenschaften, Goethe-Universitaet, Altenhoeferallee 1, D-60438 Frankfurt am Main (Germany)

    2010-05-01

    The effect of A-site incorporated Ba{sup 2+} and Bi{sup 3+} on the pressure-driven structural transformations in Pb-based perovskite-type relaxor ferroelectrics has been studied with in situ x-ray diffraction and Raman scattering of PbSc{sub 0.5}Nb{sub 0.5}O{sub 3}, Pb{sub 0.93}Ba{sub 0.07}Sc{sub 0.5}Nb{sub 0.5}O{sub 3}, and Pb{sub 0.98}Bi{sub 0.02}Sc{sub 0.51}Nb{sub 0.49}O{sub 3} in the range from ambient pressure to 9.8 GPa. The substitution of Ba{sup 2+} for Pb{sup 2+} represents the case in which A-site divalent cations with stereochemically active lone-pair electrons are replaced by isovalent cations with a larger ionic radius and no active lone pairs, leading to formation of strong local elastic fields. In contrast, substitution of Bi{sup 3+} for Pb{sup 2+} involves the replacement of divalent A-site cations with active lone-pair electrons by aliovalent cations with nearly the same ionic radius and active lone pairs so it induces local electric fields but not strong elastic fields. The two types of dopants have rather distinct effects on the changes in the atomic structure under pressure. The embedding of Ba{sup 2+} and associated elastic fields hinders the development of pressure-induced ferroic ordering and thus smears out the phase transition. The addition of Bi{sup 3+} enlarges the fraction of spatial regions with a pressure-induced ferroic distortion, resulting in a more pronounced phase transition of the average structure, i.e., the preserved lone-pair order and the absence of strong local elastic fields enhances the development of the ferroic phase at high pressure. For all compounds studied, the high-pressure structure exhibits glide-plane pseudosymmetry associated with a specific octahedral tilt configuration.

  14. Anisotropy of ferroelectric behavior of (1 - x)Bi1/2Na1/2TiO3-xBaTiO3 single crystals across the morphotropic phase boundary

    NASA Astrophysics Data System (ADS)

    Schneider, D.; Jo, Wook; Rödel, J.; Rytz, D.; Granzow, T.

    2014-07-01

    (1 - x)(Bi1/2Na1/2)TiO3-xBaTiO3 (BNT-100xBT) single crystals with three different compositions of x = 0.036, 0.065, and 0.088, covering the rhombohedral to predominantly tetragonal region of the phase diagram and encompassing the morphotropic phase boundary (MPB), were grown by top-seeded solution growth. Dielectric and ferroelectric measurements were performed on samples with different orientations with respect to the crystallographic axes. While the results complied with the current understanding of the crystallographic structure, no enhancement of electromechanical properties based on transient polarization rotation was observed. This clearly sets BNT-100xBT apart from other relaxor ferroelectric systems with a rhombohedral-tetragonal MPB such as (1 - x) Pb(Mg1/3Nb2/3)O3-xPbTiO3. An anomaly was observed in the poling behavior of the strain in <001> oriented BNT-100xBT in the immediate vicinity of the MPB with x = 0.065, resulting in a giant small-signal piezoelectric coefficient d33 of 4600 pm/V. This effect is hypothesized to be due to an irreversible phase change from rhombohedral polar nanoregions to tetragonal ferroelectric microdomains.

  15. Manganese incorporation into ferroelectric lead titanate

    Microsoft Academic Search

    Stanislav Stoupin

    2007-01-01

    Substitution with 3d magnetic transition elements in ABO 3 ferroelectric perovskite host media is widely utilized to produce relaxor ferroelectrics. Many resulting solid solutions exhibit magnetoelectric properties affected by concentration levels of the introduced magnetic ions. For conventional material preparation techniques such as firing of mechanically mixed oxides, incorporation is often limited by 5 mol% concentration level. Doping at higher

  16. Relaxor properties of Ba0.9Bi0.067(Ti1-xZrx)O3 ceramics Simon Annie, Ravez Jean, Maglione Mario

    E-print Network

    Paris-Sud XI, Université de

    of lead pollution [1]. 2. Lead-free relaxor ferroelectrics ceramics derived from BaTiO3 Depending on bothRelaxor properties of Ba0.9Bi0.067(Ti1-xZrx)O3 ceramics Simon Annie, Ravez Jean, Maglione Mario Abstract : Starting from the well-known ferroelectric material BaTiO3, we show that coupled substitutions

  17. Incipient ferroelectrics: Anomalous T1 behaviors and their rotor interpretation

    NASA Astrophysics Data System (ADS)

    Deng, Hai-Yao; Hu, Kaige; Lam, Chi Hang; Huang, Haitao

    2012-01-01

    The quantum temperature (denoted by T1) behaviors of three typical incipient ferroelectrics, SrTiO 3, KTaO 3 and CaTiO 3, are studied. This quantity is argued to serve fundamentally in identifying the nature of the local mode responsible for the dielectric responses. Our main findings are as follows. For all compounds, T1 saturates at low temperatures. For CaTiO 3, T1 monotonically increases with temperature and no clear saturation is discernible at high temperatures. For KTaO 3, similar behaviors are observed but with a little twist: a dip shows up around 35 K, above which T1 increases but below it T1 decreases with temperature. Although it is hardly seeable in this compound, this dip might mark a transition, whose nature is unclear for the moment. In parallel with KTiO 3, SrTiO 3 also has a dip, which is much stronger and broader. It happens around 105 K, at which the famous anti-ferrodistortive (AFD) transition occurs. Were it not for this dip, T1 would drop to zero in SrTiO 3 at low temperatures and the ferroelectric (FE) transition would take place. The dip halts the drop and makes T1 rise up to a value that is enough to stabilize the FE instability. In this respect, the dip is essential in preventing the FE transition in SrTiO 3. Since the dip and the AFD transition occur at roughly the same temperature, we attempt to ascribe the former to the latter. This ascription is compatible with previous work [A. Yamanaka, M. Kataoka, Y. Inaba, K. Inoue, B. Hehlen, E. Courtens, Europhys. Lett., 50:(2000) 688]. To interpret the T1 behaviors, we utilize an anisotropic rotor model, according to which the local variable is supposed to move on a non-uniform sphere. By tuning the anisotropy parameter, ?, qualitative agreement can be achieved. Especially, a single ??100 can fit the T1 of CaTiO 3 over the entire temperature range under consideration, whereas the fitting for KTaO 3 requires two different ?, namely, ??260 above the dip temperature and ??40 below it. Analogously, two ? are also required for SrTiO 3. Below the dip temperature, a very good fitting can be obtained with ??40. We did not try to fit the high temperature data of SrTiO 3, because the data in this range are scarce and inaccurate. Nevertheless, we believe that a different and bigger ? should be at work, considering the case with KTaO 3. Assuming the AFD transition as the cause of the dip in SrTiO 3, we may claim that, the true role of the AFD transition in stabilizing the FE instability is to reduce the ? and then enhance quantum fluctuations.

  18. Dielectric, structural and microstructural characteristics of tetragonal-structured PLZT relaxors

    SciTech Connect

    Dai, X.; Xu, Z.; Viehland, D. [Univ. of Illinois, Urbana, IL (United States)

    1994-12-31

    Tetragonal PLZT ceramics (Zr/Ti = 40/60) with lanthanum contents of approximately 12 atomic% posses a unique transformation. Dielectric constant measurements have revealed a spontaneous switching between relaxor and normal ferroelectric behaviors, in addition significant thermal hysteresis effects were observed near the switching temperature. Temperature dependent x-ray line broadening above the switching temperature was observed which revealed the development of significant internal strain indicating the presence of local cubic-tetragonal structural transformations which preserve the average cubic symmetry, while line splitting was observed below the switching temperature indicating the formation of a macroscopic tetragonal structure. Micropolar domain coarsening and a subsequent transformation to a normal micron-sized domain configuration was observed by hot-stage transmission electron microscopy.

  19. Synthesis and Dielectric Study of NBT- BSN: a Lead Free Relaxor Materials

    NASA Astrophysics Data System (ADS)

    Kumar, Nitin; Singh, K. N.; Bajpai, P. K.

    2011-11-01

    Solid solutions of (1-x)(Na0.5Bi0.5TiO3)—x(BaSnO3) (x = 0, 0.15, 0.20, 0.25) are successfully synthesized using conventional solid state reaction route. Formation of solid solutions is confirmed by x-ray diffraction technique. NBT stabilizes in hexagonal structural form whereas the other end member of solid solution BSN stabilizes in cubic structure. Lattice parameters (a, b) and the unit cell volume increase, whereas c-parameter decreases with increasing BSN composition. The temperature dependent dielectric constant and dc conductivity also show anomalies at phase transition and show ferroelectric relaxor behavior. Modified Curie-Weiss law is used to fit the dielectric data that exhibits almost complete diffusion phase transition characteristics.

  20. Quest for lead free relaxors in YIn(1-x)Fe(x)O? (0.0 ? x ? 1.0) system: role of synthesis and structure.

    PubMed

    Shukla, Rakesh; Sayed, Farheen N; Grover, Vinita; Deshpande, Sudhanshu K; Guleria, Apurav; Tyagi, Avesh K

    2014-10-01

    The B-site tailored YIn(1-x)Fe(x)O3 (0.0? x? 1.0) series was synthesized by glycine-aided gel-combustion technique and subjected to extensive structural and electrical investigations. The temperature had tremendous bearing on the phase evolution exhibited by the system. The entire system crystallized as C-type metastable polymorph in the as-synthesized form. Hexagonal polymorphs of Fe(3+)-rich compositions could be isolated by controlled heat treatment at 750 °C. Raman spectroscopic investigations showed that, while there is a general shrinkage of the lattice due to substitution of a smaller ion at In(3+)-site, there is an apparent dilation of the Y-O bond, and this anomaly reflects in the electrical behavior exhibited by the system. The single-phasic hexagonal nominal compositions, YIn(1-x)Fe(x)O3 (0.0 ? x ? 0.3), were also studied by impedance spectroscopy. The dielectric constant was found to drastically increase from 10 for YInO3 to 1000 for YIn(0.7)Fe(0.3)O3 at room temperature stressing the role of B-site tailoring on electrical behavior. More interestingly, careful substitution of Fe into YInO3 could tune the electrical behavior from a dielectric to relaxor ferroelectric in the temperature range studied. The nominal composition YIn(0.7)Fe(0.3)O3 showed a classical relaxor ferroelectric like behavior which is an important observation in context of the search for new lead free relaxor materials. PMID:25207665

  1. Investigation of the multiscale constitutive behavior of ferroelectric materials using advanced diffraction techniques

    NASA Astrophysics Data System (ADS)

    Rogan, Robert C.

    Ferroelectric ceramics are widely used in a diverse set of devices including sensors, actuators, and transducers. The technological importance of ferroelectrics originates from their large electromechanical coupling. Ferroelectric materials exhibit a complicated behavior in response to both electrical and mechanical loads which produce large internal stresses that eventually lead to failure. Efforts to model and predict the behavior of ferroelectrics have been hindered by the lack of suitable constitutive relations that accurately describe the electromechanical response of these materials. While many measurements have been conducted on the macroscopic response of single-crystals or polycrystals, multiaxial (and multiscale) data about the in situ internal strain and texture response of these materials is lacking; this information is critical to the development of accurate models, and diffraction techniques which directly measure internal crystal strains and material texture are aptly suited to supply it. A neutron diffraction technique was employed which allowed for the simultaneous measurement of material texture and lattice strains in directions parallel and transverse to an applied mechanical load. By comparing the behaviors of single-phase tetragonal, single-phase rhombohedral, and dual-phase morphotropic compositions, information concerning mechanics of average macroscopic behavior was inferred. In an effort to probe more of the multiaxial constitutive behavior, a high-energy X-ray diffraction technique was employed. Using transmission geometry and a 2-D image plate detector, 36 different directions of sample behavior were measured simultaneously. Polychromatic scanning X-ray microdiffraction was used to investigate the microscale three-dimensional strain tensor in single-crystals. One investigation yielded the first ever direct measurement of the tri-axial strain fields associated with single domain walls in ferroelectrics. The second investigation recorded the domain switching mechanisms activated to accommodate indentation-induced fracture stresses. Finally, 3-D XRD was used to probe the mesoscale constitutive behavior of single, embedded grains of BaTiO3 within a polycrystalline matrix. The experimental methods described in this thesis provide access to two-dimensional and three-dimensional multiaxial constitutive strain behavior in ferroelectrics for each of the microscopic , mesoscopic, and macroscopic length scales. Results from each of these length scales will provide critical data for models attempting to accurately describe the behavior of ferroelectric materials.

  2. A finite element model for rate-dependent behavior of ferroelectric ceramics

    Microsoft Academic Search

    Sang-Joo Kim; Qing Jiang

    2002-01-01

    In this article, materials within a crystallite are modeled by continuum particles consisting of various types of ferroelectric variants which are characterized by their mass fractions. The constitutive behavior of each type of variant is characterized by a proposed Helmholtz free energy potential. Polarization switching is modeled by continuous changes of mass fractions which are governed by a onset criterion

  3. Nanoscale piezoelectric and ferroelectric behaviors of seashell by piezoresponse force microscopy

    NASA Astrophysics Data System (ADS)

    Li, Tao; Zeng, Kaiyang

    2013-05-01

    Seashells, the armor of one of the most ancient species, have demonstrated outstanding mechanical properties such as simultaneous strengthening and toughening. The seashells have also been proven to exhibit piezoelectric and ferroelectric properties, which may contribute to their mechanical behaviors and various functionalities. This work has elaborated in more details of the piezoelectric and ferroelectric behaviors of the nacre by using the DART (Dual-AC Resonance Tracking) and vector-PFM (Piezoresponse Force Microscope), as well as the SS-PFM (Switching Spectroscopy PFM) techniques. By using the vector-PFM technique, the local polarization directions of intracrystalline biopolymers are found to be very close to the direction perpendicular to the platelet surface, and it, therefore, shows strong piezoresponse along this direction. On the other hand, the interlamellar biopolymer shows strong piezoresponse in the direction parallel to the platelet surface. This intrinsic piezoelectric property of the biopolymer may be the basis for sensing and actuating during biomineralization process. Besides the piezoresponse, the locations of various biopolymers are also revealed in-situ by using the PFM technique. The ferroelectric behaviors of nacre have been observed by SS-PFM method. Based on the shapes of the ferroelectric hysteresis loops, it is found that the biopolymers in nacre exhibit the similar behaviors to that of the polyvinylidene fluoride (PVDF) based co- or ter-polymers for energy storage applications.

  4. Relaxor piezoelectric film actuators, waveguides, and photonic crystals: Fabrication and characterization

    NASA Astrophysics Data System (ADS)

    Vanga, Raghav

    Microscale wavelength de-multiplexers, and tunable filters are required for emerging advances in optical communication, and light based computing systems. This particular thesis emphasizes the utilization of piezoelectric relaxor ferroelectric single crystals for MEMS based applications such as optical micro-interconnects, microvalves and chemical sensing elements. First, a novel mechanism based on electric field gradient induced piezoactuation is proposed. This mechanism makes use of an interdigitated electrode structure for the actuation and the mechanism is tested in bulk and micron scale actuators. Secondly, we have implemented the Crystal Ion Slicing technique for the fabrication of piezoelectric relaxor single crystal films from a bulk crystal. The films are characterized using X-Ray diffraction, atomic force microscopy, and electron probe microanalysis studies. Thirdly, we demonstrate for the first time optical waveguiding in piezoelectric relaxor ferroelectrics single crystals. We also demonstrate for the first time the fabrication and functioning of on-chip photonic crystals using the single crystal relaxor ferroelectrics. Tunable optical filters (one-dimensional photonic crystals) are fabricated in these single crystal materials through micro- and nano-fabrication techniques. Optical waveguides needed for the filters are fabricated through helium implantation process. A thorough characterization of the filters is done by quantifying the optical response in the infrared wavelength range through the observation of band gaps. Finally, the technologies needed for the fabrication of a microscale beam routing filter is developed. These kind of devices have immediate applications in channel add-drop filter, wavelength division multiplexers, optical interconnects etc.

  5. Relaxor piezoelectric film actuators, waveguides and photonic crystals: Fabrication and characterization

    NASA Astrophysics Data System (ADS)

    Vanga, Raghav

    Microscale wavelength de-multiplexers, and tunable filters are required for emerging advances in optical communication, and light based computing systems. This particular thesis emphasizes the utilization of piezoelectric relaxor ferroelectric single crystals for MEMS based applications such as optical micro-interconnects, microvalves and chemical sensing elements. First, a novel mechanism based on electric field gradient induced piezoactuation is proposed. This mechanism makes use of an interdigitated electrode structure for the actuation and the mechanism is tested in bulk and micron scale actuators. Secondly, we have implemented the Crystal Ion Slicing technique for the fabrication of piezoelectric relaxor single crystal films from a bulk crystal. The films are characterized using X-Ray diffraction, atomic force microscopy, and electron probe microanalysis studies. Thirdly, we demonstrate for the first time optical waveguiding in piezoelectric relaxor ferroelectrics single crystals. We also demonstrate for the first time the fabrication and functioning of on-chip photonic crystals using the single crystal relaxor ferroelectrics. Tunable optical filters (one-dimensional photonic crystals) are fabricated in these single crystal materials through micro- and nano-fabrication techniques. Optical waveguides needed for the filters are fabricated through helium implantation process. A thorough characterization of the filters is done by quantifying the optical response in the infrared wavelength range through the observation of band gaps. Finally, the technologies needed for the fabrication of a microscale beam routing filter is developed. These kind of devices have immediate applications in channel add-drop filter, wavelength division multiplexers, optical interconnects etc.

  6. High-temperature ferroelectric behaviors of poly(vinylidene fluoride-trifluoroethylene) copolymer ultrathin films with electroactive interlayers

    NASA Astrophysics Data System (ADS)

    Hou, Ying; Zhang, Xiuli; Zhang, Yuan; Xu, Guoqiang; Xu, Haisheng

    2012-03-01

    The high-temperature ferroelectric behaviors for poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) copolymer ultrathin films with electroactive interlayers have been studied. The different electroactive polymers, commercial poly(3,4-ethylene dioxythiophene)-poly(styrene sulfonic) acid (PEDOT-PSSH), in situ synthesized PEDOT-PSSH with high PEDOT ratio and poly(3,4-ethylene dioxythiophene)-poly(styrene sulfonic) ammonia (PEDOT-PSSNH4), are used as the interlayer between P(VDF-TrFE) and metal electrodes. It is found that the ferroelectric properties at high temperature are strongly dependent on the interlayer and the faster degradation occurs on the sample with the interlayer which has enough protons as compensating charges. Further analysis on the polarization response behaviors and capacitance shows that the high-temperature ferroelectric properties are more closely associated with the compensating charges in interlayer than the ferroelectric film itself, illustrating the importance of the appropriate interlayer materials.

  7. Finite-temperature properties of the relaxor PbMg1 /3Nb2 /3O3 from atomistic simulations

    NASA Astrophysics Data System (ADS)

    Al-Barakaty, A.; Prosandeev, Sergey; Wang, Dawei; Dkhil, B.; Bellaiche, L.

    2015-06-01

    An atomistic numerical scheme is developed and used to study the prototype of relaxor ferroelectrics, that is PbMg1 /3Nb2 /3O3 (PMN), at finite temperatures. This scheme not only reproduces known complex macroscopic properties of PMN, but also provides a deep microscopic insight into this puzzling system. In particular, relaxor properties of PMN are found to originate from the competition between (1) random electric fields arising from the alloying of Mg and Nb ions belonging to different columns of the Periodic Table within the same sublattice; (2) the simultaneous condensation of several off-center k points as a result of a specific short-range, antiferroelectriclike interaction between lead-centered dipoles; and (3) ferroelectriclike interactions. Such origins contrast with those recently proposed for the homovalent Ba(Zr,Ti)O3 solid solution, despite the fact that these two materials have similar macroscopic properties—which therefore leads to a comprehensive understanding of relaxor ferroelectrics.

  8. Origin of the relaxor state in Pb(BxB1-x)O3 perovskites Silvia Tinte, B. P. Burton, and Eric Cockayne

    E-print Network

    Burton, Benjamin P.

    Origin of the relaxor state in Pb(BxB1-x)O3 perovskites Silvia Tinte, B. P. Burton, and Eric.84.Dy, 64.70.Kb, 61.46.-w Perovskite-based A(B1/2B1/2)O3 and A(B1/3B2/3)O3 relaxor ferroelectrics (RFE-range chemical order that enhances relaxor properties in the important family of Pb(BxB1-x)O3 perovskites[8

  9. Memristive behaviors in Pt/BaTiO{sub 3}/Nb:SrTiO{sub 3} ferroelectric tunnel junctions

    SciTech Connect

    Wen, Zheng [College of Physics, Qingdao University, Qingdao 266071 (China); National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093, China and Department of Materials Science and Engineering, College of Engineering and Applied Sciences, Nanjing University, Nanjing 210093 (China); Wu, Di, E-mail: diwu@nju.edu.cn; Li, Aidong [National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093, China and Department of Materials Science and Engineering, College of Engineering and Applied Sciences, Nanjing University, Nanjing 210093 (China)

    2014-08-04

    We demonstrate memristive behaviors in Pt/BaTiO{sub 3}/Nb:SrTiO{sub 3} metal/ferroelectric/semiconductor ferroelectric tunnel junctions, in which the semiconductor electrode can be switched between the accumulated and the depleted states by polarization reversal in the BaTiO{sub 3} barrier via the ferroelectric field effect. An extra barrier, against electron tunneling, forms in the depleted region of the Nb:SrTiO{sub 3} electrode surface, which together with the ferroelectric barrier itself modulate the tunneling resistance with the change of effective polarization. Continuous resistance modulation over four orders of magnitude is hence achieved by application of programmed voltage pulses with different polarity, amplitude, and repetition numbers, as a result of the development of the extra barrier.

  10. Ferroelectric VDF/TrFE/CTFE terpolymers: synthesis and electric properties

    NASA Astrophysics Data System (ADS)

    Chung, T. C. Mike; Petchsuk, Atitsa

    2001-07-01

    This paper discusses a new ferroelectric polymer with high dielectric constant (>50 at 1K-1M Hz) and large electrostrictive response (~5%) at ambient temperature, which is based on a processable semicrystalline terpolymer comprising vinylidene difluoride (VDF), trifluoroethylene (TrFE), and chlorotrifluoroethylene (CTFE). This VDF/TrFE/CTFE terpolymer was prepared by a combination of a borane/oxygen initiator and bulk polymerization process at ambient temperature. The control of monomer addition afforts the terpolymers with high molecular weight and relatively narrow molecular weight and composition distributions. The incorporated bulky CTFE units homogeneously distributed along the polymer chain seem to reduce the thickness of ferroelectric crystalline domains without destroying the overall crystallinity. This nano-size semicrystalline morphology results in the reduction of ferroelectric-paraelectric (F-P) phase transition to near ambient temperature with a very small energy barrier. Some terpolymers exhibited common ferroelectric relaxor behaviors with a broad dielectric peak that shifted toward higher temperatures as the frequency increased, and a slim polarization hysteresis loop at near the dielectric peak (around ambient temperature) that gradually evolved into a normal ferroelectric polarization hysteresis loop with reduced temperature.

  11. Origin of the ``Waterfall'' Effect in Phonon Dispersion of Relaxor Perovskites

    Microsoft Academic Search

    J. Hlinka; S. Kamba; J. Petzelt; J. Kulda; C. A. Randall; S. J. Zhang

    2003-01-01

    We have undertaken an inelastic neutron scattering study of the perovskite relaxor ferroelectric Pb(Zn1\\/3Nb2\\/3)O3 with 8% PbTiO3 (PZN-8%PT) in order to elucidate the origin of the previously reported unusual kink on the low frequency transverse phonon dispersion curve (known as the ``waterfall effect''). We show that its position (qwf) depends on the choice of the Brillouin zone and that the

  12. Experimental studies on physical deterioration and electrical fatigue behavior in ferroelectric polymers

    NASA Astrophysics Data System (ADS)

    He, Xiangtong

    Ferroelectric materials are widely used in various electronic applications based upon their excellent electrical bi-stabilities and dielectric performance in response to the applied electric field. They have been utilized to make nonvolatile electronic memories by exploiting the hysteretic behavior and high energy density capacitors in regard to the high capability of electrical energy storage. One critical issue is that the ferroelectrics are required to endure a large number of electrical cycles. A large body of scientific efforts has been devoted to high fatigue failure resistance of ferroelectric-based electronic devices. Fatigue failure of ferroelectric materials still needs to be solved. It is the objective of this work to explore the intrinsic origin of fatigue failure mechanisms. In this study, it was found that electric-field-induced stress relaxation in ?-phase poly(vinylidene fluoride) (PVDF) films can be well described by using the Kohlraush function groups, also known as the stretched exponential relaxation function. The electric strength of the dielectric is strongly dependent on its elastic properties due to the electromechanical coupling effect. Our fitting result of the stretched exponent is in accordance with a Weibull cumulative distribution function. This indicates that the elastic properties of insulating polymers are crucial to the capability of electrical energy storage. In ferroelectric materials, the electromechanical coupling may be indicative of the microscopic origin of polarization fatigue. Further experiments were focused on the polarization fatigue in semi-crystalline poly(vinylidene fluoride trifluoroethylene) [P(VDF-TrFE)] copolymers films, whose ferroelectric response is superior to PVDF homopolymer films. Fatigue resistance of normal virgin P(VDF-TrFE) films was compared to that of P(VDF-TrFE) films modulated by using magnetic field. It was shown that normal P(VDF-TrFE) films exhibit a higher fatigue resistance. The artificially introduced lattice reorientation in magnetic-field-modulated P(VDF-TrFE) films would be closely related to the fatigue resistance. Under an ac electric field, the correspondingly microstructures may also influence the electrically induced lattice defects. Polarization fatigue data in P(VDF-TrFE) films was also analyzed by a dynamic Coffin-Manson law, wherein the corresponding coefficients and the exponent of the function can be estimated via different Weibull distribution function. The smallest scale found to be significant in electrical fatigue is the irreversible atomic movements. Studies on electrical failure behavior were also performed in P(VDF-TrFE) copolymer films. Experiment results consistently show that the measured electric polarization near the breakdown limit with respect to the failure life cycles obeys the Coffin-Manson law that is the most widely used to describe the mechanical fatigue failure behavior. The corresponding Coffin-Manson exponents remain constant. Our experimental evidence indicates that accumulation of the disordered structure at the atomic level is closely related to the physical origin of the fatigue in dielectric materials. It is the intrinsic atomic movement that constitutes the major finding in this work.

  13. Zone Boundary Soft Modes in Relaxor PMN

    NASA Astrophysics Data System (ADS)

    Gehring, Peter; Swainson, Ian; Stock, Chris; Xu, Guangyong; Luo, Haosu

    2008-03-01

    The lattice dynamics of PbMg1/3Nb2/3O3, a prototypical relaxor, have been studied using neutron TOF techniques at the NIST Center for Neutron Research. Unusual ``columns'' of inelastic scattering are seen at the M and R-point zone boundaries at 300,that extend from 5,eV to the elastic line. The columns weaken substantially upon heating to 600,, suggesting the existence of soft, zone boundary modes. This would imply a dynamical origin to the superlattice peaks previously observed via TEM and x-ray diffraction techniques. Preliminary neutron structure factor calculations indicate that the corresponding ionic displacements involve the Mg/Nb and Pb atoms. This picture is consistent with x-ray studies according to which the superlattice peaks result from <110> correlated, anti- parallel Pb displacements [1]. The potential relationship between the columns and superlattice peaks is intriguing because the temperature dependence of the M-point superlattice peak tracks that of the soft, zone center mode [2], which is associated with the development of short-range ferroelectric correlations. [1] A. Tkachuk and H. Chen, AIP Conf. Proc., 677, p. 55 (2003); [2] P. M. Gehring, S. Wakimoto, Z.-G. Ye, and G. Shirane, Phys. Rev. Lett. 87, 277601 (2001).

  14. Evolution of multiple dielectric responses and relaxor-like behaviors in pure and nitrogen-ion-implanted (Ba, Sr)TiO3 thin films

    NASA Astrophysics Data System (ADS)

    Yang, Jing; Gao, Yanhong; Bai, Wei; Zhang, Yuanyuan; Shen, Hong; Sun, Jinglan; Meng, Xiangjian; Duan, Chungang; Tang, Xiaodong; Chu, Junhao; meng xiangjian Team; chu junhao Team

    2015-03-01

    Multiple dielectric responses are comparatively investigated in the pure and nitrogen-ion-implanted (Ba, Sr)TiO3 (BST) films. Larger diffusive degree of phase transition and more relaxor-like features than those of pure BST films are observed in implanted ones, where the long-range-dipolar-correlated-orders were further segregated into local polar orders after the implantation. Moreover, the implanted films possess a transition from local reorientations of groups of dipoles induced nearly-constant-loss (NCL) type to oxygen vacancies (Vo) hopping type conduction at high temperature. Whereas, pure films behave as NCL type conduction along with a dielectric relaxation, which arises from the motions of defect complexes Vo2+ -Ti3+.

  15. Evolution of multiple dielectric responses and relaxor-like behaviors in pure and nitrogen-ion-implanted (Ba, Sr)TiO3 thin films

    NASA Astrophysics Data System (ADS)

    Gao, Y. H.; Yang, J.; Shen, H.; Sun, J. L.; Meng, X. J.; Chu, J. H.

    2014-03-01

    Multiple dielectric responses are comparatively investigated in the pure and nitrogen-ion-implanted (Ba, Sr)TiO3 (BST) films. Larger diffusive degree of phase transition and more relaxor-like features than those of pure BST films are observed in implanted ones, where the long-range-dipolar-correlated-orders were further segregated into local polar orders after the implantation. Moreover, the implanted films possess a transition from local reorientations of groups of dipoles induced nearly constant-loss (NCL) type to oxygen vacancies (Vo) hopping type conduction at high temperature. Whereas, pure films behave as NCL type conduction along with a dielectric relaxation, which arises from the motions of defect complexes Vo2+-Ti3+.

  16. A field model interpretation of crack initiation and growth behavior in ferroelectric ceramics: change of poling direction and boundary condition

    Microsoft Academic Search

    G. C. Sih

    2002-01-01

    Strain energy density expressions are obtained from a field model that can qualitatively exhibit how the electrical and mechanical disturbances would affect the crack growth behavior in ferroelectric ceramics. Simplification is achieved by considering only three material constants to account for elastic, piezoelectric and dielectric effects. Cross interaction of electric field (or displacement) with mechanical stress (or strain) is identified

  17. Sol-gel technology for ferroelectric thin films

    SciTech Connect

    Kim, You Song [Research Institute of Industrial Science and Technology, Pohang (Korea, Democratic People`s Republic of); Jang, Hyun M. [Pohang Univ. of Science and Technology (Korea, Democratic People`s Republic of)

    1994-12-31

    Sol-gel-derived ferroelectric thin films can offer particular promise for various microelectronic applications, including FRAM, DRAM elements, thin-film capacitors and pyroelectric IR sensors. In this article, recent progress in the sol-gel processing of two typical ferroelectric thin-film systems is briefly reviewed. These are lead zirconate titanate (PZT) solid solution and Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}-based relaxor ferroelectrics. Several examples of the sol chemistry-structures/ferroelectric properties relationships are illustrated using various recent data, including results from the authors` laboratory.

  18. Enhanced ferroelectric and ferromagnetic properties in lead-free multilayer composite films based on ferroelectric (Bi0.5Na0.5)0.945Ba0.055TiO3 and multiferroic BiFeO3

    NASA Astrophysics Data System (ADS)

    Perez-Rivero, A.; Ricote, J.; Bretos, I.; García-Hernández, M.; Calzada, M. L.; Jiménez, R.

    2015-02-01

    The study of the functional properties of the multilayer composite films of ferroelectric (Bi0.5Na0.5)0.945Ba0.055TiO3 (BNBT) and multiferroic BiFeO3 (BF) obtained by chemical solution deposition has been performed in this work. First, it has been observed a significant improvement of the remnant polarization of the multilayer composite with respect to the single phase film of BNBT: Pr = 32 ?C × cm-2, which is comparable with the values reported for bulk BNBT. This is a consequence of the stabilization of the ferroelectric domains of BNBT, although the relaxor character is still present. The leakage currents, which prevent the full exploitation of the properties of BF films, are reduced thanks to the combination with insulator BNBT layers. Besides, the magnetic behavior shows values of remnant magnetization at room temperature that makes this multilayer composites promising for multiferroic applications.

  19. Electric-field-controlled interface strain coupling and non-volatile resistance switching of La{sub 1-x}Ba{sub x}MnO? thin films epitaxially grown on relaxor-based ferroelectric single crystals

    SciTech Connect

    Zheng, Ming; Zhu, Qiu-Xiang; Li, Xue-Yan; Yang, Ming-Min; Li, Xiao-Min; Shi, Xun; Luo, Hao-Su; Zheng, Ren-Kui, E-mail: zrk@ustc.edu [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Wang, Yu [Department of Applied Physics, The Hong Kong Polytechnic University, Hong Kong (China)

    2014-09-21

    We have fabricated magnetoelectric heterostructures by growing ferromagnetic La{sub 1-x}Ba{sub x}MnO? (x=0.2, 0.4) thin films on (001)-, (110)-, and (111)-oriented 0.31Pb(In{sub 1/2}Nb{sub 1/2})O?-0.35Pb(Mg{sub 1/3}Nb{sub 1/2})O?-0.34PbTiO? (PINT) ferroelectric single-crystal substrates. Upon poling along the [001], [110], or [111] crystal direction, the electric-field-induced non-180° domain switching gives rise to a decrease in the resistance and an enhancement of the metal-to-insulator transition temperature TC of the films. By taking advantage of the 180° ferroelectric domain switching, we identify that such changes in the resistance and TC are caused by domain switching-induced strain but not domain switching-induced accumulation or depletion of charge carriers at the interface. Further, we found that the domain switching-induced strain effects can be efficiently controlled by a magnetic field, mediated by the electronic phase separation. Moreover, we determined the evolution of the strength of the electronic phase separation against temperature and magnetic field by recording the strain-tunability of the resistance [(?R/R){sub strain}] under magnetic fields. Additionally, opposing effects of domain switching-induced strain on ferromagnetism above and below 197 K for the La?.?Ba?.?MnO? film and 150 K for the La?.?Ba?.?MnO? film, respectively, were observed and explained by the magnetoelastic effect through adjusting the magnetic anisotropy. Finally, using the reversible ferroelastic domain switching of the PINT, we realized non-volatile resistance switching of the films at room temperature, implying potential applications of the magnetoelectric heterostructure in non-volatile memory devices.

  20. Electric-field-controlled interface strain coupling and non-volatile resistance switching of La1-xBaxMnO3 thin films epitaxially grown on relaxor-based ferroelectric single crystals

    NASA Astrophysics Data System (ADS)

    Zheng, Ming; Zhu, Qiu-Xiang; Li, Xue-Yan; Yang, Ming-Min; Wang, Yu; Li, Xiao-Min; Shi, Xun; Luo, Hao-Su; Zheng, Ren-Kui

    2014-09-01

    We have fabricated magnetoelectric heterostructures by growing ferromagnetic La1-xBaxMnO3 (x = 0.2, 0.4) thin films on (001)-, (110)-, and (111)-oriented 0.31Pb(In1/2Nb1/2)O3-0.35Pb(Mg1/3Nb1/2)O3-0.34PbTiO3 (PINT) ferroelectric single-crystal substrates. Upon poling along the [001], [110], or [111] crystal direction, the electric-field-induced non-180° domain switching gives rise to a decrease in the resistance and an enhancement of the metal-to-insulator transition temperature TC of the films. By taking advantage of the 180° ferroelectric domain switching, we identify that such changes in the resistance and TC are caused by domain switching-induced strain but not domain switching-induced accumulation or depletion of charge carriers at the interface. Further, we found that the domain switching-induced strain effects can be efficiently controlled by a magnetic field, mediated by the electronic phase separation. Moreover, we determined the evolution of the strength of the electronic phase separation against temperature and magnetic field by recording the strain-tunability of the resistance [(?R/R)strain] under magnetic fields. Additionally, opposing effects of domain switching-induced strain on ferromagnetism above and below 197 K for the La0.8Ba0.2MnO3 film and 150 K for the La0.6Ba0.4MnO3 film, respectively, were observed and explained by the magnetoelastic effect through adjusting the magnetic anisotropy. Finally, using the reversible ferroelastic domain switching of the PINT, we realized non-volatile resistance switching of the films at room temperature, implying potential applications of the magnetoelectric heterostructure in non-volatile memory devices.

  1. VOLUME 84, NUMBER 25 P H Y S I C A L R E V I E W L E T T E R S 19 JUNE 2000 Crossover from Glassy to Inhomogeneous-Ferroelectric Nonlinear Dielectric Response

    E-print Network

    Pirc, Rasa

    to Inhomogeneous-Ferroelectric Nonlinear Dielectric Response in Relaxor Ferroelectrics Vid Bobnar, Zdravko Kutnjak single crystal and in 9 65 35 PLZT ceramics has been determined by measuring the first and third harmonic to a spherical glass, while above the critical field a transition into a ferroelectric state occurs. PACS numbers

  2. Dielectric, piezoelectric, and ferroelectric properties of grain-orientated Bi{sub 3.25}La{sub 0.75}Ti{sub 3}O{sub 12} ceramics

    SciTech Connect

    Liu Jing; Shen Zhijian; Yan Haixue; Reece, Michael J.; Kan Yanmei; Wang Peiling [Department of Inorganic Chemistry, Arrhenius Laboratory, Stockholm University, S-106 91 Stockholm (Sweden); Department of Materials, Queen Mary University of London, Mile End Road, London E1 4NS (United Kingdom); Shanghai Institute of Ceramics, Chinese Academy of Science, 1295 Dingxi Road, Shanghai 200050 (China)

    2007-11-15

    By dynamic forging during Spark Plasma Sintering (SPS), grain-orientated ferroelectric Bi{sub 3.25}La{sub 0.75}Ti{sub 3}O{sub 12} (BLT) ceramics were prepared. Their ferroelectric, piezoelectric, and dielectric properties are anisotropic. The textured ceramics parallel and perpendicular to the shear flow directions have similar thermal depoling behaviors. The d{sub 33} piezoelectric coefficient of BLT ceramics gradually reduces up to 350 deg. C; it then drops rapidly. The broadness of the dielectric constant and loss peaks and the existence of d{sub 33} above the permittivity peak, T{sub m}, show that the BLT ceramic has relaxor-like behavior.

  3. Characterization of nonlinear behavior in a tunable phase shifter using ferroelectric PZT thin-film capacitors and its effect on system performance

    Microsoft Academic Search

    J. X. Qiu; D. C. Judy; J. S. Pulskamp; R. G. Polcawich; R. Kaul; F. Crowne

    2009-01-01

    In this paper, the nonlinear behavior in a tunable phase shifter using ferroelectric lead zirconate titanate (PZT) thin-film capacitors is described. The phase shifter is of reflection-type consisting of a coplanar waveguide Lange coupler and two ferroelectric PZT varactors on high resistivity silicon substrate. The nonlinearity is characterized by measuring the AM\\/AM and AM\\/PM transfer curves of the device, a

  4. A Mesoscopic Electromechanical Theory of Ferroelectric Films and Ceramics

    E-print Network

    Bhattacharya, Kaushik

    A Mesoscopic Electromechanical Theory of Ferroelectric Films and Ceramics Jiangyu Li and Kaushik the effective electromechanical behavior of ferroelectric ceramics and thin films. This paper specifically actuation strains in ferroelectric single crystals through polarization rotation [1, 2] , or by domain

  5. Ferroelectric fluoro-terpolymers with high dielectric constant and large electromechanical response at ambient temperature

    NASA Astrophysics Data System (ADS)

    Chung, T. C.; Petchsuk, Atitsa

    2003-08-01

    This paper discusses a new family of ferroelectric polymorphs fluoro-terpolymers comprising vinylidene difluoride (VDF), trifluoroethylene (TrFE), and a chloro-containing third monomer, including vinyl chloride (VC), 1,1-chlorofluoroethylene (CFE), chlorodifluoroethylene (CDFE), chlorotrifluoroethylene (CTFE), with narrow molecular weight and composition distributions. The slightly bulky chlorine atom serves as a kink in the polymer chain, which spontaneously alters the chain conformation and crystalline structure. Comparing with the corresponding VDF/TrFE copolymer, the slowly increasing chlorine content (< 8 mol% of ter-monomer) gradually changes the all-trans chain conformation to tttg+tttg- conformation, without significant reduction of overall crystallinity. Curie (F-P) phase transition temperature between the mixed ferroelectric phases and paraelectric phase (tg+tg- conformation) also gradually reduced to near ambient temperature, with very small activation energy. Consequently, the terpolymers show high dielectric constant (>80) and large electrostrictive response (>5%) at ambient temperature, and exhibiting common ferroelectric relaxor behaviors with a broad dielectric peak that shifted toward higher temperatures as the frequency increased, and a slim polarization hysteresis loop at ambient temperature.

  6. Dielectric and Mössbauer studies of ferroelectric and magnetic phase transitions in A-site and B-site substituted multiferroic PbFe0.5Nb0.5O3.

    PubMed

    Raevski, Igor P; Kubrin, Stanislav P; Raevskaya, Svetlana I; Prosandeev, Sergey A; Malitskaya, Maria A; Titov, Victor V; Sarychev, Dmitry A; Blazhevich, Aleksei V; Zakharchenko, Irina N

    2012-09-01

    In the present study, we diluted either A- or B- sublattice of perovskite multiferroic PbFe(0.5)Nb(0.5)O(3) (PFN) and studied the changes of the magnetic and ferroelectric phase transition temperatures and dielectric properties caused by such dilution. Dielectric studies of PFN single crystals show that, in contrast to the commonly adopted view, the ferroelectric phase transition in PFN is non-diffused and the relaxor-like behavior usually observed in ceramic samples has an extrinsic nature. A-site substitutions (Ba, Ca) lead to the smearing of the permittivity-temperature maximum, lowering its maximum temperature, T(m) and inducing relaxor behavior. B-site diluting of PFN by Ti increases T(m) and only slightly affects the permittivity maximum diffuseness. Both A-site and B-site substitutions in PFN lead to lowering of its Neel temperature, T(N). However, above a certain compositional threshold, fast lowering of T(N) stops and a new magnetic state with comparatively high (~50K) transition temperature becomes stable in a rather wide compositional range. PMID:23007753

  7. Elastic behavior of PbTiO{sub 3} crystals near ferroelectric phase transition

    SciTech Connect

    Dul`kin, E.A. [Rostov State Univ., Rostov-na-Donu (Russian Federation)

    1995-03-01

    Domain structures arising in multiaxial ferroelectric crystals below the Curie point (T{sub c}) are generally a superposition of the 180{degrees} ferroelectric domains and 180{degrees} mechanical domains (twins). The latter domains are characterized by spontaneous strains directed along different crystallographic axes and form the so called ferroelastic phase within the crystal bulk. The twins in the ferroelectric phase are packed in such a way that the net strain (taking into account the sign of strain in each domain) vanishes in the crystals. The simplest example of such packing has the phase divided into 90{degrees} twins. In this case, the spontaneous strain along the axis normal to the twinning plane is lacking in the crystals. The 90{degrees} twins are typical of perovskite crystals. Therefore, this paper deals with PbTiO{sub 3} crystals. 7 refs., 2 figs.

  8. Influence of Quantum Zero Point Energy on the Ferroelectric Behavior of Isomorphous Systems

    Microsoft Academic Search

    C. ARAGÓ; J. GARCÍA; J. A. GONZALO; C. L. WANG; W. L. ZHONG; X. Y. XUE

    2004-01-01

    The influence of the relative amount of zero point energy in the double potential wells associated with reorientable dipoles in ferroelectric systems has been investigated. The quantitative dependence of the dielectric constant ?, the saturation polarization PS0 and the critical temperature TC as a function of zero point energy =??0\\/2 = kBT was determined from the appropriate quantum effective field

  9. Relaxor-based solid solutions for piezoelectric and electrostrictive applications

    NASA Astrophysics Data System (ADS)

    Alberta, Edward F.

    This thesis explores the dielectric, piezoelectric, and electrostrictive properties of a number of relaxor ferroelectric-based solid solution systems. The components of these solid solution systems have a variety of characteristics ranging from normal- to relaxor- to anti-ferroelectric. Some of the relaxor end-members investigated were Pb(In1/2Nb1/2)O3 [PIN], Pb(In1/2Ta1/2)O3 [PIT], Pb(Sc 1/2Nb1/2)O3 [PSN], Pb(Ni1/3Nb 2/3)O3 [PNN], Pb(Mg1/3Nb2/3)O 3 [PMN], and Pb(Zn1/3Nb2/3)O3 [PZN]. Several of these systems have Curie temperatures [Tc] that are among the highest known for MPB compositions. Some examples are PIN-0.38PT with a Tc of 319°C, PIT-0.38PT with a Tc of 248°C, and PSN 0.42PT with a Tc of 254°C. While these are slightly lower that those of typically found in PZT, the temperature dependence of the piezoelectric properties was found to be minimal. The electromechanical coupling coefficients were largely unchanged upon heating to as high as 150°C. This is approximately equal to the Tc of PMN-PT and PZN-PT and significantly exceeds the generally accepted maximum operating temperature for these materials. Many of the materials studied were found to have very large electromechanical coupling factors and produce extraordinarily high field-induced strains. Both PSN-0.42PT and PNN-0.15PZ-0.34PT were found to produce strain levels of ˜0.30% under unipolar drive with limited hysteresis. Peak-to-peak strain levels of as much as 0.60% were possible under bipolar drive conditions. Both of these MPB compositions had very large piezoelectric properties, with the slightly larger values of d33 = 810pC/N, kp = 0.69, kt = 0.56, and k33 = 0.80 occurring in PNN-PZ-PT. Each of the MPB compositions studied has features that can be exploited for specific applications. The combination of high Tc and coercive field found in both PIN-PT and Bi(Ni1/2T1/2)O3 -PT should allow these materials to be used at high drive levels and/or at high temperatures. The high strain, low hysteresis, and large piezoelectric properties found in PSN-PT and PNN-PZ-PT indicate that these could be excellent actuators as well as ultrasound transducers. Other materials such as PIN-PbZrO 3, have large anisotropy in the electromechanical coupling coefficients (k33 = 0.29 and k31 = 0.04) that leads to large hydrostatic piezoelectric figures-of-merit. The 1-x(PSN-PT)-x(PZN-PT) pseudo binary system was also successfully used to show that relaxor-based ternary systems could be used to combine the features of two MPB compositions, in this case for example, the high Tc and temperature stability of PSN-PT with the low cost and easy crystal growth of PZN-PT. Macro- to micro-domain transitions occurred in many of the relaxor-relaxor solid solutions including both the PIN-PMN and PSN-PMN solid solutions. Large values of the electrostrictive coefficient similar to that of pure PMN were also measured. The PIN-PMN system exhibited particularly low levels of strain hysteresis. The ability to compositionally tune the properties of these systems will be advantageous in the design of room temperature IR sensors, micropositioners, and capacitors. The PIN-PNN system was determined to have large values of the pyroelectric coefficient at low temperatures. With appropriate compositional tuning the pyroelectric coefficient can be maximized at 77K making this an excellent candidate for cooled pyroelectric imaging.

  10. Nonlinear electric-mechanical behavior of a soft PZT51 ferroelectric ceramic

    Microsoft Academic Search

    Daining Fang; Changqing Li

    1999-01-01

    In this investigation, the electric-mechanical response of a PZT ferroelectric ceramic subjected to the combined electric-mechanical loads was experimentally observed. The effect of different compressive stress levels on the electromechanical response was examined. The stress-strain relationship was also measured. The ceramic sample was isolated from the test frame and the high voltage arcing were prevented effectively in the setup which

  11. Ferroelectric Pump

    NASA Technical Reports Server (NTRS)

    Jalink, Antony, Jr. (Inventor); Hellbaum, Richard F. (Inventor); Rohrbach, Wayne W. (Inventor)

    2000-01-01

    A ferroelectric pump has one or more variable volume pumping chambers internal to a housing. Each chamber has at least one wall comprising a dome shaped internally prestressed ferroelectric actuator having a curvature and a dome height that varies with an electric voltage applied between an inside and outside surface of the actuator. A pumped medium flows into and out of each pumping chamber in response to displacement of the ferroelectric actuator. The ferroelectric actuator is mounted within each wall and isolates each ferroelectric actuator from the pumped medium, supplies a path for voltage to be applied to each ferroelectric actuator, and provides for positive containment of each ferroelectric actuator while allowing displacement of the entirety of each ferroelectric actuator in response to the applied voltage.

  12. Magnetoelectric relaxor A. Levstik,a

    E-print Network

    Bobnar, Vid

    between the local nanocluster polarizations and magnetizations. Magnetoelectric multiferroics can the magnetic properties at all here. The important point is that magnetoelectric effects have been ob- servedMagnetoelectric relaxor A. Levstik,a V. Bobnar, C. Filipic, J. Holc, M. Kosec, and R. Blinc Jozef

  13. Organic ferroelectrics

    Microsoft Academic Search

    Sachio Horiuchi; Yoshinori Tokura

    2008-01-01

    Ferroelectricity results from one of the most representative phase transitions in solids, and is widely used for technical applications. However, observations of ferroelectricity in organic solids have until recently been limited to well-known polymer ferroelectrics and only a few low-molecular-mass compounds. Whereas the traditional use of dipolar molecules has hardly succeeded in producing ferroelectricity in general, here we review advances

  14. Ferroelectric properties of vinylidene fluoride copolymers

    Microsoft Academic Search

    Takeo Furukawa

    1989-01-01

    Ferroelectric properties of copolymers of vinylidene fluoride with trifluoroethylene and tetrafluoroethylene are described with special interest in their polarization reversal and phase transition behavior. The ferroelectric phase consists of all-trans molecules packed in a parallel fashion while molecules adopt irregular TT, TG, T[Gbar] conformations in the paraelectric phase. In the ferroelectric phase, polarization reversal occurs at very high fields (>

  15. Nanoscale Observation of Poling Behaviors in Nd-Substituted Bi4Ti3O12 Ferroelectric Thin Films

    NASA Astrophysics Data System (ADS)

    Shin, Ran Hee; Hye Lee, Ji; Kim, Gracia; Jo, William; Kim, Dae Hyun; Lee, Hyun Jin; Kang, Jeongsoo

    2010-09-01

    In this study, the effects of oxygen vacancies on the local poling properties of Bi-layered ferroelectric thin films were examined. Bi3.15Nd0.85Ti3O12 (BNT) thin films were coated on Pt(111)/Ti/SiO2/Si substrates using a sol-gel method. An oxygen vacancy of 2.4±0.5% was observed mainly at the Bi2O22+ layers in the film that annealed in an oxygen-deficient atmosphere. The film containing oxygen vacancies showed a shift in the polarization-electric field hysteresis loop. Contact-mode electrostatic force microscopy revealed a domain pinning behavior in the BNT film with oxygen vacancies. The unpolarized domains were explained by the built-in field formed by the oxygen vacancies in the Bi2O22+ layers.

  16. SISGR – Domain Microstructures and Mechanisms for Large, Reversible and Anhysteretic Strain Behaviors in Phase Transforming Ferroelectric Materials

    SciTech Connect

    Wang, Yu

    2013-12-06

    This four-year project (including one-year no-cost extension) aimed to advance fundamental understanding of field-induced strain behaviors of phase transforming ferroelectrics. We performed meso-scale phase field modeling and computer simulation to study domain evolutions, mechanisms and engineering techniques, and developed computational techniques for nanodomain diffraction analysis; to further support above originally planned tasks, we also carried out preliminary first-principles density functional theory calculations of point defects and domain walls to complement meso-scale computations as well as performed in-situ high-energy synchrotron X-ray single crystal diffraction experiments to guide theoretical development (both without extra cost to the project thanks to XSEDE supercomputers and DOE user facility Advanced Photon Source).

  17. Low-temperature switching fatigue behavior of ferroelectric SrBi2Ta2O9 thin films

    NASA Astrophysics Data System (ADS)

    Yuan, G. L.; Liu, J.-M.; Zhang, S. T.; Wu, D.; Wang, Y. P.; Liu, Z. G.; Chan, H. L. W.; Choy, C. L.

    2004-02-01

    The ferroelectric hysteresis and fatigue behavior over a wide temperature range from 290 to 50 K for SrBi2Ta2O9 thin films with Pt electrodes on silicon substrates, prepared by metalorganic decomposition (MOD) and pulsed-laser deposition (PLD), are investigated. It is found that given a fixed electrical field amplitude, the coercivity of all films increases with decreasing temperature T. The saturated hysteresis loop easily obtained for the MOD-prepared thin films has its remnant polarization enhanced with decreasing T, but the PLD-prepared samples exhibit minor loops whose remnant polarization decays with decreasing T. While the films prepared by MOD exhibit improved fatigue resistance at low T, significant fatigue effect at low T is observed for the films prepared by PLD. Although we cannot rule out the effect of strain, the experimental results can be explained by competition between pinning and depinning of domain walls, which are dependent of temperature and defect charges.

  18. Crystal structure and dielectric properties of ferroelectric ceramics in the BaO-Sm 2O 3-TiO 2Nb 2O 5 system

    Microsoft Academic Search

    X. H. Zheng; X. M. Chen

    2003-01-01

    Some tungsten–bronze ferroelectrics were synthesized and characterized in the BaO-Sm2O3-TiO2-Nb2O5 system. Ba4Sm2Ti4Nb6O30 and Ba5SmTi3Nb7O30 had the tetragonal filled tungsten–bronze structure; while Ba3Sm3Ti5Nb5O30 consisted of the orthorhombic tungsten–bronze major phase and the BaTi4O9 secondary phase. The present dielectric ceramics exhibited relaxor behavior with the maximum temperatures around 185, 285 and 130°C for Ba3Sm3Ti5Nb5O30, Ba4Sm2Ti4Nb6O30 and Ba5SmTi3Nb7O30, respectively. Moreover, Ba3Sm3Ti5Nb5O30 exhibited a

  19. High-temperature memory in (Pb/La)(Zr/Ti)O3 as intrinsic of the relaxor state rather than due to defect relaxation

    NASA Astrophysics Data System (ADS)

    Cordero, F.; Craciun, F.; Franco, A.; Galassi, C.

    2006-07-01

    It has been recently shown that the memory of multiple aging stages, a phenomenon considered possible only below the glass transition of some glassy systems, appears also above that temperature range in the relaxor ferroelectric (Pb/La)(Zr/Ti)O3 (PLZT). Doubts exist whether memory at such high temperature is intrinsic of the glassy relaxor state or is rather due to migration of mobile defects. It is shown that the memory in the electric susceptibility and elastic compliance of PLZT 9/65/35 is not enhanced but depressed by mobile defects like O vacancies, H defects, and mobile charges resulting from their ionization. In addition, memory is drastically reduced at La contents slightly below the relaxor region of the phase diagram, unless aging is protracted for long times (months at room temperature). This is considered as evidence that in the nonrelaxor case memory is indeed due to slow migration of defects, while in the La rich case it is intrinsic of the relaxor state, even above the temperature of the susceptibility maximum.

  20. Ferroelectricity in Si-doped HfO2 revealed: a binary lead-free ferroelectric.

    PubMed

    Martin, Dominik; Müller, Johannes; Schenk, Tony; Arruda, Thomas M; Kumar, Amit; Strelcov, Evgheni; Yurchuk, Ekaterina; Müller, Stefan; Pohl, Darius; Schröder, Uwe; Kalinin, Sergei V; Mikolajick, Thomas

    2014-12-23

    Static domain structures and polarization dynamics of silicon doped HfO2 are explored. The evolution of ferroelectricity as a function of Si-doping level driving the transition from paraelectricity via ferroelectricity to antiferroelectricity is investigated. Ferroelectric and antiferroelectric properties can be observed locally on the pristine, poled and electroded surfaces, providing conclusive evidence to intrinsic ferroic behavior. PMID:25352107

  1. Dielectric and Ferroelectric Behavior of Bismuth-Doped Barium Titanate Ceramic Prepared by Microwave Sintering

    NASA Astrophysics Data System (ADS)

    Mahapatra, A.; Parida, S.; Sarangi, S.; Badapanda, T.

    2014-12-01

    Bismuth-doped barium titanate ceramics with the general formula Ba1-x Bi2x/3TiO3 (x = 0.0, 0.01, 0.025, 0.05) have been prepared by the solid state reaction technique. The phase formation and structural property of all compositions have been studied by x-ray diffraction (XRD) pattern and Rietveld refinement. XRD pattern reports the single phase tetragonal crystal system with space group of P4mm. All compositions have been sintered at 1100°C in a microwave furnace for 30 min. The variation of dielectric constant with respect to temperature and frequency was studied and it was found that the dielectric constant decreases whereas transition temperature increased with the increase in Bi content. The diffusivity parameter was calculated by the modified Curie-Weiss law and the diffusivity increased with the increase in Bi content. The ferroelectric property was studied by the P-E hysteresis loop and it was observed that the saturation polarization decreased, but the coercive field increased with Bi content. The optical band gap was calculated from UV-Visible spectroscopy and found to decrease with Bi content.

  2. Anisotropic Optical Behavior of Ferroelectric Bismuth Titanate: A Comparison of Experiment and Theory

    NASA Astrophysics Data System (ADS)

    Roy, Amritendu; Prasad, Rajendra; Auluck, Sushil; Garg, Ashish

    2010-03-01

    Optical properties of bismuth titanate (Bi4Ti3O12 or BiT) are of technological interest as its band gap lies in the visible region. Here we compare the results of theoretical and experimental studies conducted on pure bismuth titanate single crystals. Highly oriented BiT single crystals were synthesized using flux growth method. Spectroscopic ellipsometry measurements were made between 300 to 800 nm for different sample orientations. To obtain the absorption coefficient near the band edge, optical transmission measurements were also made. The refractive index data was fitted to a two-term Sellmeier formula. We also calculated the optical constants for both ferroelectric and paraelectric phases of bismuth titanate using density functional theory as implemented in the Vienna ab-initio simulation package (VASP) in conjunction with projector augmented wave method (PAW). Our calculations show the anisotropy of the optical properties for the electric field parallel and perpendicular to the c-axis of the crystal. Our calculations are in good agreement with the experimental data.

  3. Measuring and Altering Ferroelectric Domain Structures in Lead Perovskite Single-Crystals

    NASA Astrophysics Data System (ADS)

    Harker, John Chamberlain

    Relaxor ferroelectric single-crystal materials PMN-PT and PZN-PT are currently of interest to the scientific community due to their enhanced properties and possible role as next-generation piezoelectric transducers in applications such as sonar and medical ultrasound. One key phenomenon affecting both the properties and the mechanical integrity of these materials is the ferroelectric domain structure within the material. In this work we examine the morphology and behavior of domain structures in PMN-29%PT. In order to do this we first present details of the construction and testing of a working piezo-response force microscope (PFM), and then use the PFM to verify a new domain observation technique called "relief polishing". Relief polishing is shown to reveal surface domains in the same manner as acid etching, preserving domain details as small as 0.5mum. Using these two techniques, we then determine that cutting and polishing strongly affect the surface and subsurface ferroelectric domain structures in PMN-29%PT. Specifically, we show that saw cutting can create characteristic striated domain structures as deep as 130mum within a sample, while straight polishing creates a characteristic domain structure known as the "fingerprint" pattern to a depth proportional to the size of the polishing grit, on the order of 0--12mum for grits as large as 15mum. We hypothesize that most samples contain these "skin effect" domain structures. In consequence, it is suggested that researchers presenting experimental results on domain structures should report the physical treatment history of the samples along with the experimental data.

  4. Polarization behavior of poly(vinylidene fluoride-trifluoroethylene) copolymer ferroelectric thin film capacitors for nonvolatile memory application in flexible electronics

    NASA Astrophysics Data System (ADS)

    Mao, D.; Mejia, I.; Stiegler, H.; Gnade, B. E.; Quevedo-Lopez, M. A.

    2010-11-01

    The time domain and electric field dependence of the polarization switching kinetics of poly(vinylidene fluoride-trifluoroethylene) copolymer based thin film metal-ferroelectric-metal capacitors have been characterized. At room temperature, the time required for complete switching polarization decreases from >1 s to <50 ?s as the voltage is increased from 6 to 12 V, while low nonswitching polarization is maintained. In the time domain, the ferroelectric switching polarization reversal behavior for devices biased above the coercive field follows the nucleation-limited-switching model. The exponential relationship between switching time and applied electric field indicates nucleation dominated switching kinetics. Switching behavior as a function of temperature was also characterized from -60 to 100 °C in the voltage range of 6-12 V. Higher temperatures induce larger dc conductance leakage at low frequencies and increases nonswitching polarization for all the voltages studied. It is demonstrated that for certain frequencies, by controlling the switching voltage, our optimized ferroelectric thin film capacitor shows stable switching polarization in a temperature range compatible with flexible electronics applications.

  5. Ferroelectric/ferroelastic behavior and piezoelectric response of lead zirconate titanate thin films under nanoindentation

    SciTech Connect

    Koval, V.; Reece, M.J.; Bushby, A.J. [Department of Materials, Queen Mary University of London, Mile End Road, London, E1 4NS (United Kingdom)

    2005-04-01

    The electromechanical response of pure lead zirconate titanate (PZT) and Mn-doped PZT thin ferroelectric films under nanoindentation forces of up to 500 mN was investigated. The stress-induced current transients were measured as a function of the externally applied load on films of different thicknesses using a spherical WC-Co cermet indenter of 500 {mu}m nominal radius. It was found that the quasi-static current generated through the direct piezoelectric effect is superimposed with a contribution from irreversible domain processes during the loading/unloading cycle. The film thickness dependency of the electrical transients and an asymmetry of the current-force curves are attributed to the in-plane clamping stress in the films produced by a dissimilar substrate. Analysis of corresponding charge-force hysteresis loops revealed a significant role for the residual stress state on the polarization switching in thin films. By the application of an indentation force, a portion of Barkhausen jumps was empirically estimated to increase as a consequence of reduction of the clamping effect on domains. The Rayleigh hysteretic charge-force curves showed recovery of the charge released during the load-unload stress cycle. For the thicker 700 nm films, the total charge released during loading was fully recovered with weak hysteresis. In contrast, strong in-plane clamping stresses in the 70 nm thick films are suggested to be reponsible for incomplete recovery upon unloading. A considerable domain-wall contribution to the electromechanical response was demonstrated by an enhanced polarization state, which was shown by an increase of the effective piezoelectric coefficient d{sub eff} of about 35% of its initial value for the thin films at a maximum force of 500 mN.

  6. Spatially resolved mapping of ferroelectric switching behavior in self-assembled multiferroic nanostructures: strain, size, and interface effects

    Microsoft Academic Search

    Brian J. Rodriguez; Stephen Jesse; Arthur P. Baddorf; T. Zhao; Y. H. Chu; R. Ramesh; Eugene A. Eliseev; Anna N. Morozovska; Sergei V. Kalinin

    2007-01-01

    Local ferroelectric polarization switching in multiferroic BiFeO3-CoFe2O4 nanostructures is studied using switching spectroscopy piezoresponse force microscopy (SS-PFM). Dynamic parameters such as the work of switching are found to vary gradually with distance from the heterostructure interfaces, while nucleation and coercive biases are uniform within the ferroelectric phase. We demonstrate that the electrostatic and elastic fields at interfaces do not affect

  7. Linear electro-optic properties of relaxor-based ferroelectric 0.24Pb(In1/2Nb1/2)O3-(0.76 - x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 single crystals

    NASA Astrophysics Data System (ADS)

    Wu, Fengmin; Yang, Bin; Sun, Enwei; Liu, Gang; Tian, Hao; Cao, Wenwu

    2013-07-01

    Linear electro-optic properties of 0.24Pb(In1/2Nb1/2)O3-(0.76 - x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 single crystals, with compositions in the rhombohedral, morphotropic phase boundary (MPB) and tetragonal phases, have been investigated. Very large effective electro-optic coefficient ?c (204 pm/V) was observed in a crystal with the MPB composition when it is poled along [001]. The rhombohedral phase (x = 0.27 and 0.30) single crystals poled along [111] direction and tetragonal phase (x = 0.39) single crystal poled along [001] direction are in single domain, and their electro-optic coefficients (?c = 76, 94, and 43 pm/V for the crystals with x = 0.27, 0.30, and 0.39, respectively) were found to be much higher than that of traditional electro-optic single crystal LiNbO3 (?c = 19.9 pm/V). The electro-optic coefficients of the single crystal in the rhombohedral phase have excellent temperature stability in the experimental temperature range of 10-40 °C. The half-wave voltage V? was calculated to be much lower (less than 1000 V) than that of LiNbO3 single crystal (2800 V). These superior properties make the ternary relaxor-PT single crystals very promising for electro-optic modulation applications.

  8. Large strain response based on relaxor-antiferroelectric coherence in Bi0.5Na0.5TiO3-SrTiO3-(K0.5Na0.5)NbO3 solid solutions

    NASA Astrophysics Data System (ADS)

    Liu, Laijun; Shi, Danping; Knapp, Michael; Ehrenberg, Helmut; Fang, Liang; Chen, Jun

    2014-11-01

    The effect of (K0.5Na0.5)NbO3 (KNN) addition on the ferroelectric and dielectric behavior of 90Bi0.5Na0.5TiO3-10SrTiO3 (BNT-ST) lead-free piezoceramics was investigated. Polarization and strain hysteresis loops indicate that a relaxor-antiferroelectric coherence will be produced with the addition of KNN as a replacement for ST up to 5% and the destabilization of the phase coherence is accompanied by an enhancement of the bipolar strain with the increase of temperature, which is ˜0.37% (corresponding to a large signal d33* of ˜530 pm/V at 90 °C) at 5 mol. % KNN content. This strain was analyzed as derived from an electrostrictive effect at lower electric fields and a field-induced antiferroelectric-ferroelectric phase transition at higher electric fields. The large polar strain response would be of great interest for environmental friendly high-temperature actuators.

  9. Specific features of switching processes in soft ferroelectric ceramics based on lead zirconate-titanate

    NASA Astrophysics Data System (ADS)

    Akbaeva, G. M.; Borodin, V. Z.

    2015-03-01

    Switching processes in soft ferroelectric ceramic materials based on lead zirconate-titanate have been studied. It has been found that these materials, which possess properties of relaxors and have an additional low-frequency phase transition between two rhombohedral phases, R3 c ? R3 m, exhibit specific features upon the repolarization near this transition: in addition to the decrease in the coercive field, the domain compression effect disappears, which indicates changes in the switching mechanism.

  10. Effect of strain on ferroelectric and magnetic behavior in Pb(Zr0.52Ti0.48)O3-based magnetoelectric heterostructures.

    PubMed

    Huang, W; Zeng, H Z; Zhu, J; Hao, J H; Dai, J Y

    2011-12-01

    In this paper, the "sandwich" structured magnetoelectric composite films of Pb(Zr0.52Ti0.48)O3/ NiFe2O4/Pb(Zr0.52Ti0.48)O3 and Pb(Zr0.52Ti0.48)O3/CoFe2O4/Pb(Zr0.52Ti0.48)O3 are epitaxially grown on SrRuO3/SrTiO3 substrates by pulsed-laser deposition. The crystalline quality and microstructures of these heterostructures are investigated by X-ray diffraction technique. The effects of strain on the ferroelectric, magnetic and magnetoelectric coupling properties of these thin films are systematically studied. The results show that the strain effect induced by lattice mismatch between the ferroelectric/ferromagnetic layers plays an important role in the ferroelectric and magnetic properties of these composite films. Compared to the strained Pb(Zr0.52Ti0.48)O3/ CoFe2O4/Pb(Zr0.52Ti0.48)O3 heterostructure, improved ferroelectric properties with an out-of-plane polarization (2P(r)) of 34.2 microC/cm2 and electric coercivity field of 158 kV/cm are obtained in the strain-free Pb(Zr0.52Ti0.48)O3/NiFe2O4/Pb(Zr0.52Ti0.48)O3 heterostructure. The ME measurement results not only show that the strain induced by lattice mismatch has great influence on the ME behavior, but also provide an understanding of the multilayers with full control over the interface structure at the atomic-scale. PMID:22409090

  11. Two kinds of anomalous dielectric phenomena in Pr-doped SrTiO 3 ceramics: The Debye-like and ferroelectric-like behaviors

    NASA Astrophysics Data System (ADS)

    Liu, Cheng; Liu, Peng

    2010-12-01

    Sr 1 -xPr xTiO 3 ceramics (0.00? x?0.07) were investigated over a broad temperature and frequency range for their interesting dielectric behaviors. Two kinds of anomalous dielectric behaviors were observed, i.e. Debye-like relaxation behaviors for the specimens of x?0.03 and ferroelectric-like dielectric peaks appearing in x?0.04. According to our experiments, the Debye-like relaxation, as well as the CDC behavior ( ?r?3000) detected in x=0.01, was closely related to the IBLC mechanism. The anomalous dielectric peaks appearing in x?0.04 were ascribed to an electron transportation process instead of a TF-P.

  12. Temperature-dependent coherent oscillation in photorefractive relaxor strontium barium

    E-print Network

    Osnabrück, Universität

    Temperature-dependent coherent oscillation in photorefractive relaxor strontium barium niobate M of the photorefractive light-induced scattering (beam fanning) in Sr0.61Ba0.39Nb2O6 (strontium barium niobate) doped

  13. Resistive switching via the converse magnetoelectric effect in ferromagnetic multilayers on ferroelectric substrates.

    PubMed

    Pertsev, N A; Kohlstedt, H

    2010-11-26

    A voltage-controlled resistive switching is predicted for ferromagnetic multilayers and spin valves mechanically coupled to a ferroelectric substrate. The switching between low- and high-resistance states results from the strain-driven magnetization reorientations by about 90°, which are shown to occur in ferromagnetic layers with a high magnetostriction and weak cubic magnetocrystalline anisotropy. Such reorientations, not requiring external magnetic fields, can be realized experimentally by applying moderate electric field to a thick substrate (bulk or membrane type) made of a relaxor ferroelectric having ultrahigh piezoelectric coefficients. The proposed multiferroic hybrids exhibiting giant magnetoresistance may be employed as electric-write nonvolatile magnetic memory cells with nondestructive readout. PMID:21030777

  14. Size effects in a relaxor: further insights into PMN.

    PubMed

    Grigalaitis, R; Ivanov, M; Macutkevic, J; Banys, J; Carreaud, J; Kiat, J M; Laguta, V V; Zalar, B

    2014-07-01

    Dielectric measurements of PbMg1/3Nb2/3O3 (PMN) powder and dense ceramics with grain sizes between 15?nm and two microns were carried out in a broad frequency range (20?Hz-1?GHz). Clear grain size dependence of relaxor behavior was evidenced. A progressive transformation from Vogel-Fulcher behavior towards the Arrhenius process in the PMN with reduction of grain size in both ceramics and powder was observed. In the case of ceramics we were able to extract deeper information from the distributions of relaxation times and an analysis using the Vogel-Fulcher law, revealing two main contributions: a fast part of distribution of relaxation times with a maximum close to 10(-11)?s, which is almost grain-size independent and has a non-polar origin; whereas, a process with long relaxation times (in the time range of 10(-8)?to 10(-5)?s) is associated with the dynamics of the polar nanoregions and is strongly suppressed with reduction of grain size. The results of dielectric investigations are confirmed by Nuclear Magnetic Resonance experiments. PMID:24925462

  15. Size effects in a relaxor: further insights into PMN

    NASA Astrophysics Data System (ADS)

    Grigalaitis, R.; Ivanov, M.; Macutkevic, J.; Banys, J.; Carreaud, J.; Kiat, J. M.; Laguta, V. V.; Zalar, B.

    2014-07-01

    Dielectric measurements of PbMg1/3Nb2/3O3 (PMN) powder and dense ceramics with grain sizes between 15?nm and two microns were carried out in a broad frequency range (20?Hz-1?GHz). Clear grain size dependence of relaxor behavior was evidenced. A progressive transformation from Vogel-Fulcher behavior towards the Arrhenius process in the PMN with reduction of grain size in both ceramics and powder was observed. In the case of ceramics we were able to extract deeper information from the distributions of relaxation times and an analysis using the Vogel-Fulcher law, revealing two main contributions: a fast part of distribution of relaxation times with a maximum close to 10-11?s, which is almost grain-size independent and has a non-polar origin; whereas, a process with long relaxation times (in the time range of 10-8?to 10-5?s) is associated with the dynamics of the polar nanoregions and is strongly suppressed with reduction of grain size. The results of dielectric investigations are confirmed by Nuclear Magnetic Resonance experiments.

  16. Ferroelectric precursor behavior of highly cation-ordered PbSc0.5Ta0.5O3 detected by acoustic emission: Tweed and polar nanoregions

    NASA Astrophysics Data System (ADS)

    Dul'kin, Evgeniy; Salje, Ekhard K. H.; Aktas, Oktay; Whatmore, Roger W.; Roth, Michael

    2014-11-01

    Highly ordered ferroelectric PbSc0.5Ta0.5O3 crystals were studied by acoustic emission over a wide temperature range. Acoustic emission was found at three characteristic temperatures: 330, 409, and ?600 K, which are close to those, known from the same disordered crystals, containing polar nanoregions. The microstructure in our crystals contains structural "tweed" rather than nanoregions. The coincidence of acoustic emission temperatures points towards a close structural relationship between nanoregions and "tweed." Under electric field, these temperatures shift similar to "critical end point" behavior. The obtained data prove that acoustic emission detects signals in a wider parameter space than previously expected.

  17. Relaxor behaviour of low lead and lead free ferroelectric ceramics of the Na 0.5Bi 0.5TiO 3–PbTiO 3 and Na 0.5Bi 0.5TiO 3–K 0.5Bi 0.5TiO 3 systems

    Microsoft Academic Search

    Jean-Pierre Mercurio

    2001-01-01

    Ceramics with compositions belonging to the Na0.5Bi0.5TiO3–PbTiO3 and Na0.5Bi0.5TiO3–K0.5Bi0.5TiO3 systems were fabricated by natural sintering of powders prepared by thermal decomposition of adequate precursor solutions. The ferroelectric to paraelectric phase transitions were studied by variable temperature X-ray diffractometry, differential scanning calorimetry and impedance measurement in a wide range of temperature and frequency. In contrast with pure NBT, both the permittivity

  18. Interaction of Terahertz Radiation with Ferroelectrics

    NASA Astrophysics Data System (ADS)

    Nelson, Keith

    2007-03-01

    Ferroelectric crystals have long been used as acoustic transducers and receivers. An extensive toolset has been developed for MHz-frequency acoustic wave generation, control, guidance, and readout. In recent years, an analogous toolset has been developed for terahertz wave transduction and detection. Femtosecond optical pulses irradiate ferroelectric crystals to generate responses in the 0.1-5 THz frequency range that are admixtures of electromagnetic and polar lattice vibrational excitations called phonon-polaritons. Spatiotemporal femtosecond pulse shaping may be used to generate additional optical pulses that arrive at specified times and sample locations for control and manipulation of the THz waves. Femtosecond laser machining may be used for fabrication of waveguides, resonators, and other structures that are integrated into the ferroelectric host crystal. Finally, real-space imaging of the THz fields can be executed with variably delayed femtosecond probe pulses, permitting direct visualization of THz wave spatial and temporal evolution. This ``polaritonics'' toolset enables multiplexed generation of arbitrary THz waveforms and use of the waveforms within the ferroelectric host crystal or after projection into free space or an adjacent medium. The polaritonics platform will be reviewed and several new developments and applications will be presented. These include spectroscopy of relaxor ferroelectrics, whose temperature-dependent dielectric responses in the GHz-THz regime reveal complex polarization dynamics on well separated fast and slow time scales; direct measurement of phonon-polariton lattice vibrational displacements through femtosecond time-resolved x-ray diffraction; generation of high polariton field amplitudes and pulse energies; use of large-amplitude polariton waves to drive nonlinear lattice vibrational responses; and enhancement of optical-to-THz conversion efficiency through a pseudo-phase-matching approach that circumvents the very large disparity between refractive index values at optical and THz frequencies.

  19. Manganese incorporation into ferroelectric lead titanate

    NASA Astrophysics Data System (ADS)

    Stoupin, Stanislav

    Substitution with 3d magnetic transition elements in ABO 3 ferroelectric perovskite host media is widely utilized to produce relaxor ferroelectrics. Many resulting solid solutions exhibit magnetoelectric properties affected by concentration levels of the introduced magnetic ions. For conventional material preparation techniques such as firing of mechanically mixed oxides, incorporation is often limited by 5 mol% concentration level. Doping at higher concentrations requires introduction of other substituents to compensate charge within the unit cell to promote formation of the perovskite phase. In contrast, molecular mixing of precursor materials at the initial phase of preparation procedure offers an advantage of achieving higher incorporation levels of the 3d elements without additional charge-compensating ions. Presented in this thesis is a new sol-gel procedure utilized for high level incorporation of 3d magnetic ions into ferroelectric lead titanate. The technique was applied to produce PbTi1-xMnxO 3 solid solution, a perovskite system promising for high degree of magnetoelectric coupling. Concentration dependent studies were performed to characterize structural, thermal, ferroelectric and magnetic properties of the material. The solubility limit of Mn has been found to be 20 mol% and the material remains tetragonally distorted. X-ray Absorption Spectroscopy confirms that local structural environment of Mn, Ti, and Pb is consistent with tetragonal symmetry of the unit cell. Increase in Mn concentration leads to reduction in melting point, broadening of the ferroelectric transition, reduction of the transition temperature and increase in dielectric constant of the material. At the solubility limit the system was found to be ferromagnetic below 50 K.

  20. Effect of grain orientation and grain size on ferroelectric domain switching and evolution: Phase field simulations

    E-print Network

    Chen, Long-Qing

    rights reserved. Keywords: Ceramics; Phase field models; Grain boundaries; Ferroelectricity 1. Introduction Ferroelectric ceramics are used in microelectronics where the switching behavior of ferroelectrics in ferroelectric ceramics. However, it is often difficult to separate the role of grain boundaries in determining

  1. Magnetite (Fe3O4): a new variant of relaxor multiferroic?

    PubMed

    Ziese, M; Esquinazi, P D; Pantel, D; Alexe, M; Nemes, N M; Garcia-Hernández, M

    2012-02-29

    The electric polarization, dielectric permittivity, magnetoelectric effect, heat capacity, magnetization and ac susceptibility of magnetite films and polycrystals were investigated. The electric polarization of magnetite films with saturation values between 4 and 8 ?C cm(-2) was found to vanish between 32 and 38 K, but in polycrystals no phase transition was detected in this range by heat capacity. Both types of samples showed magnetoelectric effects at low temperatures below a frequency-dependent crossover. This is interpreted as arising from multiferroic relaxor behavior. PMID:22314835

  2. Magnetite (Fe3O4): a new variant of relaxor multiferroic?

    NASA Astrophysics Data System (ADS)

    Ziese, M.; Esquinazi, P. D.; Pantel, D.; Alexe, M.; Nemes, N. M.; Garcia-Hernández, M.

    2012-02-01

    The electric polarization, dielectric permittivity, magnetoelectric effect, heat capacity, magnetization and ac susceptibility of magnetite films and polycrystals were investigated. The electric polarization of magnetite films with saturation values between 4 and 8 µC cm-2 was found to vanish between 32 and 38 K, but in polycrystals no phase transition was detected in this range by heat capacity. Both types of samples showed magnetoelectric effects at low temperatures below a frequency-dependent crossover. This is interpreted as arising from multiferroic relaxor behavior.

  3. Analytical model of the ferroelectric radiation detector

    Microsoft Academic Search

    J. T. Klopcic; D. L. Swanson

    1973-01-01

    As part of the Defense Nuclear Agency project Jl1 AAXPX231 to study the ; behavior of the ferroelectric radiation detector, an analytical model of the ; energy balance within a ferroelectric crystal has been developed. This model ; relates ionic spacing and charges to macroscopic quantities such as the ; pyroelectric and piezoelectric coefficients. Although a highly simplified model, ;

  4. Ferroelectric behaviors and charge carriers in Nd-doped Bi{sub 4}Ti{sub 3}O{sub 12} thin films

    SciTech Connect

    Gao, X.S.; Xue, J.M.; Wang, J. [Department of Materials Science, Faculty of Science, National University of Singapore, Singapore 119260 (Singapore)

    2005-02-01

    Nd-doped Bi{sub 4}Ti{sub 3}O{sub 12} thin films (Bi{sub 3.25}Nd{sub 0.85}){sub 4}Ti{sub 3}O{sub 12}, of layered perovskite structure were synthesized by rf sputtering, followed by postannealing at 600-700 deg. C. They show enhanced ferroelectricity with rising postannealing temperature in the range of 650-750 deg. C. When annealed at 700 deg. C, a remanent polarization 2P{sub r} of 25.2 {mu}C/cm{sup 2} and a coercive field E{sub c} of 87.2 kV/cm were measured at 9 V, together with an almost fatigue-free behavior up to 1.4x10{sup 10} switching cycles. Their ferroelectric, dielectric, and ac conductivity properties over the temperature range from 25 to 300 deg. C were studied over the frequency range of 0.1-1 MHz. Space-charge relaxation by oxygen vacancies was shown to play an important role in determining the dielectric and conductivity behaviors of Nd-doped Bi{sub 4}Ti{sub 3}O{sub 12} thin films.

  5. Solid-state single and triple-quantum 93Nb MAS NMR studies of ferroelectric Pb(Mg1/3Nb2/3)O3 and a related pyrochlore.

    PubMed

    Cruz, L P; Rocha, J; Pedrosa de Jesus, J D; Savariault, J M; Galy, J

    1999-12-01

    Pb(Mg1/3Nb2/3)O3 (PMN), a well-known relaxor ferroelectric material, and a related pyrochlore phase have been studied by single- and triple-quantum 93Nb MAS NMR spectroscopy. The assignment of the NMR resonances has been attempted. PMID:10672939

  6. Observation of bi-relaxor characteristic in multiferroic 0.70Bi0.90Ca0.10FeO3-0.30PbTiO3 ceramics

    NASA Astrophysics Data System (ADS)

    Tirupathi, Patri; Chandra, Amreesh

    2013-09-01

    The coexistence of bi-relaxor property, i.e. ferroelectric relaxor as well as spin glass type behaviour, is observed in disordered multiferroic ceramic 0.70Bi0.90Ca0.10FeO3-0.30PbTiO3. The real parts of dielectric permittivity and magnetic susceptibility show pronounced frequency dispersion near the corresponding phase transition temperatures, namely, Tc ? 550 K and TN ? 110 K, respectively. The relaxor behaviour observed in temperature-dependent dielectric constant measurement is confirmed by fitting of the Vogel-Fulcher equation. Similarly, magnetic spin glass behaviour is proven by power law fitting. The origin of such bi-relaxor in the present system can be attributed to the disorder and frustration among the uncompensated spins of the Fe-ion. This has been confirmed by analysing the x-ray photoelectron (XPS) spectrum of the sample under investigation. Using FESEM micrographs, the coexistence of nano-sized and bulk grains is shown. The importance of such coexistence is discussed and also presented in the paper.

  7. Dynamics of the phase transitions in Bi-layered ferroelectrics with Aurivillius structure: Dielectric response in the terahertz spectral range

    E-print Network

    Ku?el, Petr

    , a relaxor ferroelectric BaBi2Nb2O9 , and intermediate-type compound Sr0.5Ba0.5Bi2Ta2O9 . The lowest range 0.1­2 THz at temperatures 10­950 K. Although previous structural studies suggested a displacive polarization and can be deposited at lower temperatures.6,7 Much effort has been devoted to the specification

  8. Thickness-dependent ferroelectric behavior of predominantly (117)-oriented Bi3.15Nd0.85Ti3O12 thin-film capacitors

    NASA Astrophysics Data System (ADS)

    Yang, Feng; Zhang, Fuwei; Hu, Guangda; Zong, Zhihao; Tang, Minghua

    2015-04-01

    Ferroelectric hysteresis loops, remanent polarization, coercive field, and leakage current characteristics were investigated by increasing the film thickness (from 103 nm to 401 nm) of predominantly (117)-oriented Bi3.15Nd0.85Ti3O12 films. The thickness dependence of the coercive fields shows log coercive field vs. log thickness with a slope of approximately -0.65, which is characteristics of the Kay-Dunn scaling law. The films exhibited very low leakage current on the order of 10-7A/cm2 at an applied electric field of 100 kV/cm. Without a discernible thickness-dependence behavior, the leakage current characteristics, including both Schottky emission and space-charge-limited conduction, were well described by a modified Schottky contact model.

  9. Ferroelectricity in Strain-Free SrTiO3 Thin Films

    SciTech Connect

    Jang, J H [Univeristy of Wisconsson; Kumar, Amit [Pennsylvania State University; Denev, Sava [Pennsylvania State University, University Park, PA; Biegalski, Michael D [ORNL; Maksymovych, Petro [ORNL; Bark, C [University of Wisconsin, Madison; Nelson, Craig T [University of Michigan; Folkman, C H [University of Wisconsin; Baek, Seung Hyub [University of Wisconsin, Madison; Balke, Nina [ORNL; Brooks, Charles M. [Pennsylvania State University; Tenne, Demetri A. [Boise State University; Schlom, Darrell [Pennsylvania State University; Chen, Long-Qing [Pennsylvania State University; Pan, X Q [University of Michigan; Kalinin, Sergei V [ORNL; Gopalan, Venkatraman [ORNL; Eom, Professor Chang-Beom [University of Wisconsin, Madison

    2010-01-01

    Biaxial strain is known to induce ferroelectricity in thin films of nominally nonferroelectric materials such as SrTiO3. However, even strain-free SrTiO3 films and the paraelectric phase of strained films exhibit bulk frequency-dependent polarization hysteresis loops on the nanoscale at room temperature, and stable switchable domains at 50 K. By a direct comparison of the strained and strain-free SrTiO3 films using dielectric, ferroelectric, Raman, nonlinear optical and nanoscale piezoelectric property measurements, we conclude that SrTiO3 films and bulk crystals are relaxor ferroelectrics, and the role of strain is to stabilize longer-range correlation of preexisting nanopolar regions, likely originating from minute amounts of unintentional Sr-deficiency in nominally stoichiometric samples. These findings highlight the sensitive role of stoichiometry when exploring strain and epitaxy-induced electronic phenomena in oxidefilms, heterostructures and interfaces.

  10. Ferroelectricity in strain-free SrTiO3 thin films.

    PubMed

    Jang, H W; Kumar, A; Denev, S; Biegalski, M D; Maksymovych, P; Bark, C W; Nelson, C T; Folkman, C M; Baek, S H; Balke, N; Brooks, C M; Tenne, D A; Schlom, D G; Chen, L Q; Pan, X Q; Kalinin, S V; Gopalan, V; Eom, C B

    2010-05-14

    Biaxial strain is known to induce ferroelectricity in thin films of nominally nonferroelectric materials such as SrTiO3. By a direct comparison of the strained and strain-free SrTiO3 films using dielectric, ferroelectric, Raman, nonlinear optical and nanoscale piezoelectric property measurements, we conclude that all SrTiO3 films and bulk crystals are relaxor ferroelectrics, and the role of strain is to stabilize longer-range correlation of preexisting nanopolar regions, likely originating from minute amounts of unintentional Sr deficiency in nominally stoichiometric samples. These findings highlight the sensitive role of stoichiometry when exploring strain and epitaxy-induced electronic phenomena in oxide films, heterostructures, and interfaces. PMID:20866998

  11. Ferroelectric properties of charge-ordered ? -(BEDT-TTF ) 2I3

    NASA Astrophysics Data System (ADS)

    Lunkenheimer, P.; Hartmann, B.; Lang, M.; Müller, J.; Schweitzer, D.; Krohns, S.; Loidl, A.

    2015-06-01

    A detailed investigation of the out-of-plane electrical properties of charge-ordered ? -(BEDT-TTF ) 2I3 provides clear evidence for ferroelectricity. Similar to multiferroic ? -(BEDT-TTF ) 2Cu[N (CN ) 2]Cl , the polar order in this material is ascribed to the occurrence of bond- and site-centered charge order. Dielectric response typical for relaxor ferroelectricity is found deep in the charge-ordered state. We suggest an explanation in terms of the existence of polar and nonpolar stacks of the organic molecules in this material, preventing long-range ferroelectricity. The results are discussed in relation to the formation or absence of electronic polar order in related charge-transfer salts.

  12. Polarization fatigue in Pb(Zn1/3Nb2/3)O3-PbTiO3 ferroelectric single crystals

    NASA Astrophysics Data System (ADS)

    Ozgul, Metin; Takemura, Koichi; Trolier-McKinstry, Susan; Randall, Clive A.

    2001-05-01

    Pb(Zn1/3Nb2/3)O3-PbTiO3 (PZN-PT) single crystal ferroelectrics have been studied to determine the relative rates of polarization fatigue. It was recently found that ferroelectrics with the rhombohedral phase in the PZN-PT solid solution have essentially no polarization fatigue in the [001]C directions (all of the orientations in this article will be given in terms of the prototype cubic (m3m) axes, denoted by the subscript C). In this study, we expand upon this observation to correlate fatigue rates more completely with respect to composition, orientation, temperature, and electric field strength. It is inferred that an engineered domain state in relaxor based ferroelectric crystals with the spontaneous polarization inclined to the normal of the electrode is associated with negligible or no fatigue at room temperature. However, if thermal history, temperature, or field strength induces a phase transition that produces a polarization parallel to the normal of electrode, these orientations fatigue. The relative fatigue rates are also studied as a function of temperature. In directions, such as [111]C in the ferroelectric rhombohedral phase, the polarization fatigues at room temperature, but as temperature is increased the fatigue rate systematically decreases. This is explained in terms of a thermally activated process that limits the net fatigue rate of ferroelectrics. In summary, this article gives information on the polarization states and orientation that control fatigue in ferroelectric crystals with a relaxor end member.

  13. A quaternary lead based perovskite structured materials with diffuse phase transition behavior

    SciTech Connect

    Puli, Venkata Sreenivas, E-mail: pvsri123@gmail.com [Department of Physics and Institute for Functional Nano Materials, University of Puerto Rico, San Juan, PR 00936 (United States); Martinez, R.; Kumar, Ashok [Department of Physics and Institute for Functional Nano Materials, University of Puerto Rico, San Juan, PR 00936 (United States)] [Department of Physics and Institute for Functional Nano Materials, University of Puerto Rico, San Juan, PR 00936 (United States); Scott, J.F. [Department of Physics and Institute for Functional Nano Materials, University of Puerto Rico, San Juan, PR 00936 (United States) [Department of Physics and Institute for Functional Nano Materials, University of Puerto Rico, San Juan, PR 00936 (United States); Cavendish Laboratory, Dept. Physics, University of Cambridge, Cambridge CB0 3HE (United Kingdom); Katiyar, Ram S., E-mail: rkatiyar@uprrp.edu [Department of Physics and Institute for Functional Nano Materials, University of Puerto Rico, San Juan, PR 00936 (United States)

    2011-12-15

    Graphical abstract: (a) Curie-Weiss plot for the inverse of the relative dielectric permittivity and (b) log (1/{epsilon} - 1/{epsilon}{sub m}) as function of log (T - T{sub m}) for ceramics at 1 kHz. Highlights: Black-Right-Pointing-Pointer Retaining phase pure structure with quaternary complex stoichiometric compositions. Black-Right-Pointing-Pointer P-E loops with good saturation polarization (P{sub s} {approx} 30.7 {mu}C/cm{sup 2}). Black-Right-Pointing-Pointer Diffused relaxor phase transition behavior with {gamma} estimated is {approx}1.65. -- Abstract: A lead based quaternary compound composed of 0.25(PbZr{sub 0.52}Ti{sub 0.48}O{sub 3}) + 0.25(PbFe{sub 0.5}Ta{sub 0.5}O{sub 3}) + 0.25 (PbF{sub 0.67}W{sub 0.33}O{sub 3}) + 0.25(PbFe{sub 0.5}Nb{sub 0.5}O{sub 3}) - (PZT-PFT-PFW-PFN) was synthesized by conventional solid-state reaction techniques. It showed moderate high dielectric constant, low dielectric loss, and two diffuse phase transitions, one below the room temperature {approx}261 K and other above {approx}410 K. X-ray diffraction (XRD) patterns revealed a tetragonal crystal structure at room temperature where as scanning electron micrograph (SEM) indicates inhomogeneous surface with an average grain size of 500 nm-3 {mu}m. Well saturated ferroelectric hysteresis loops with good saturation polarization (spontaneous polarization, P{sub s} {approx} 30.68 {mu}C/cm{sup 2}) were observed. Temperature-dependent ac conductivity displayed low conductivity with kink in spectra near the phase transition. In continuing search for developing new ferroelectric materials, in the present study we report stoichiometric compositions of complex perovskite ceramic materials: (PZT-PFT-PFW-PFN) with diffuse phase transition behavior. The crystal structure, dielectric properties, and ferroelectric properties were characterized by XRD, SEM, dielectric spectroscopy, and polarization. 1/{epsilon} versus (T) plots revealed diffuse relaxor phase transition (DPT) behavior. The compositional variation on the phase transition temperature, dielectric constant, and ferroelectric to paraelectric phase transitions are discussed.

  14. Differentiating Ferroelectric and Nonferroelectric Electromechanical Effects with Scanning Probe Microscopy.

    PubMed

    Balke, Nina; Maksymovych, Petro; Jesse, Stephen; Herklotz, Andreas; Tselev, Alexander; Eom, Chang-Beom; Kravchenko, Ivan I; Yu, Pu; Kalinin, Sergei V

    2015-06-23

    Ferroelectricity in functional materials remains one of the most fascinating areas of modern science in the past several decades. In the last several years, the rapid development of piezoresponse force microscopy (PFM) and spectroscopy revealed the presence of electromechanical hysteresis loops and bias-induced remnant polar states in a broad variety of materials including many inorganic oxides, polymers, and biosystems. In many cases, this behavior was interpreted as the ample evidence for ferroelectric nature of the system. Here, we systematically analyze PFM responses on ferroelectric and nonferroelectric materials and demonstrate that mechanisms unrelated to ferroelectricity can induce ferroelectric-like characteristics through charge injection and electrostatic forces on the tip. We will focus on similarities and differences in various PFM measurement characteristics to provide an experimental guideline to differentiate between ferroelectric material properties and charge injection. In the end, we apply the developed measurement protocols to an unknown ferroelectric material. PMID:26035634

  15. Electric field and humidity effects on adsorbed water behavior on BaTiO3 ferroelectric domains studied by scanning probe microscopy

    E-print Network

    Volinsky, Alex A.

    affects ferroelectrics performance. For oxide ceramics, like Al2O3, ZrO2, and YBa2Cu3O7, delayed fracture­3 For ferroelectric ceramics, like PbZr1-xTixO3 (PZT) and BaTiO3, SCC could also occur in humid air, due to adsorption, which adsorb on the material surface, cause delayed cracking and fracture of ferroelectric ceramics.15

  16. Nanoscale ordering and multiferroic behavior in Pb(Fe1/2Ta1/2)O3

    NASA Astrophysics Data System (ADS)

    Martinez, R.; Palai, R.; Huhtinen, H.; Liu, J.; Scott, J. F.; Katiyar, R. S.

    2010-10-01

    We report on structural, microstructural, dielectric, electrical, magnetic, and spectroscopic (Raman and terahertz) properties of lead iron tantalate Pb(Fe1/2Ta1/2)O3 ceramics. Raman spectroscopy revealed the presence of nanoscale ordering though it is forbidden in bulk by crystal symmetry. The dielectric properties of Pb(Fe1/2Ta1/2)O3 show a typical relaxor ferroelectric behavior with long-range disorder while the magnetoelectric properties show an interesting multiferroic behavior (coexistence of ferroelectric and magnetic order) in the same phase. The temperature variation in field cooled magnetization shows anomalies at about 55(±5) and 180(±5)K indicating the existence of two Néel temperatures in agreement with theoretical predictions. The zero-field-cooled magnetization as a function temperature and field reveals the existence of spin-glasslike behavior at low temperature like single crystal. The electrical conduction behavior satisfies the modified Schottky equation of Simmons at all fields. The ac conductivity as a function of frequency shows an excellent fit to the universal power law. Terahertz spectroscopy shows an opaque nature of Pb(Fe1/2Ta1/2)O3 in midinfrared and far-infrared wavelengths.

  17. Giant Electrocaloric Effect in Ferroelectric Polymers with Great Impact on Energy and Environment

    NASA Astrophysics Data System (ADS)

    Li, Xinyu; Qian, Xiaoshi; Gu, Haiming; Lu, Shengguo; Zhang, Qiming

    2012-02-01

    Refrigeration and air conditioning overall consume around 20% of the energy budget in developed countries which necessitates a search for new approaches to increase the energy efficiency of these cooling technologies. Cooling technologies based on the electrocaloric effect (ECE) hold great potential and promise in realizing these goals. The electrocaloric effect (ECE) refers to the change in temperature and/or entropy of a dielectric material by an applied voltage. Recently, a class of P(VDF-TrFE) based ferroelectric polymers have been discovered that provide a giant electrocaloric effect with an adiabatic temperature change of ?T ˜ 20 K and an isothermal entropy change ?S > 90 J/kgK at room temperature. This talk will review the earlier works in the ECE, as well as present the basic materials considerations and experimental results of the ECE in both normal and relaxor ferroelectric polymers. It will be shown he relaxor ferroelectric polymer displays a nearly flat ECE response over a broad temperature range, which is very attractive for practical cooling device applications Furthermore, we will present our recent investigation, exploiting the giant ECE in these polymers for cooling devices with compact size, high cooling power and efficiency.

  18. Preparation and evaluation of ferroelectric thin films

    SciTech Connect

    Ogawa, Toshio [Shizuoka Institute of Science and Technology, Fukuroi (Japan)

    1994-12-31

    The stoichiometry of film compositions prepared by RF magnetron sputtering and laser ablation is discussed. Control of the crystal orientation of the films was determined from the relation between the films and substrates. In addition, a new bottom electrode material in place of platinum was developed for use with ferroelectric thin films. The ferroelectric properties and fatigue behavior of the films were evaluated with the new electrodes.

  19. Study of nanostructural behavior and transport properties of BaTiO 3 doped vanadate glasses and glass-ceramics dispersed with ferroelectric nanocrystals

    NASA Astrophysics Data System (ADS)

    Al-Assiri, M. S.; El-Desoky, M. M.; Al-Hajry, A.; Al-Shahrani, A.; Al-Mogeeth, A. M.; Bahgat, A. A.

    2009-05-01

    Nanostructural behavior and electrical properties of BaTiO 3-(100- x)V 2O 5 glasses (where x=35, 40, 45 and 50 mol%) and their corresponding nanocrystalline glass-ceramics were studied. Scanning electron microscopy (SEM) of quenched glasses, confirm the amorphous nature of the glasses present. Also, the overall features of X-ray diffraction (XRD) confirm the amorphous nature of the present glasses. Transmission electron micrograph (TEM) and XRD of the corresponding heat treated sample indicate nanocrystals with a particle size of 20-35 nm. It was found that density ( d) increases gradually with the increase of the BaTiO 3 content in the nanocrystalline glass-ceramics. It is observed that the conductivity of the nanocrystalline glass-ceramics is higher than that of the corresponding glassy phase. The high conductivity of these nanocrystalline glass-ceramics is considered to be due to the presence of nanocrystals with a particle size of 20-35 nm. This is attributed to the formation of extensive and dense network of electronic conduction paths which are situated between V 2O 5 nanocrystals and on their surface. The electrical conductivity of this system can be fitted with Mott's model of nearest neighbor hopping at high temperature. From the best fits, reasonable values of various small polaron hopping (SPH) parameters are obtained. From dielectric permittivity of the as-cast glass samples, no ferroelectric behavior can be observed. Also, the dielectric permittivity ( ?) values of these glasses are found to be very high compared to familiar vanadium containing glasses. By annealing the glass system around 450 °C for 1 h in air, nanocrystalline BaTiO 3 phase precipitates and the corresponding nanocrystalline glass-ceramics showed average broad peak around 352 K in the dielectric permittivity ( ?). It is interesting to note that pure nanocrystalline BaTiO 3 phase with average particle size less than 100 nm also shows ferroelectric phase transition around this temperature as predicted from the dielectric permittivity measurements. This observation of these glass-ceramics nanocrystals can be utilized to control BaTiO 3 particle size and hence transition temperature by proper adjustment of annealing time and BaTiO 3 content. Such a feature can be used for industrial applications where the shape of the application article is a necessary requirement.

  20. Ferroelectric ultrathin perovskite films

    DOEpatents

    Rappe, Andrew M; Kolpak, Alexie Michelle

    2013-12-10

    Disclosed herein are perovskite ferroelectric thin-film. Also disclosed are methods of controlling the properties of ferroelectric thin films. These films can be used in a variety materials and devices, such as catalysts and storage media, respectively.

  1. ARTICLES--Outstanding Meeting Papers Domain switch toughening in polycrystalline ferroelectrics

    E-print Network

    growth was analyzed to determine the toughening due to domain switching in ferroelectric ceramics the material behavior of the ferroelectric ceramic. The constitutive law is then implemented within the finite and cited accordingly. Ferroelectric ceramics have large electromechanical coupling effects and hence

  2. Uncoupled, asymptotic mode III and mode E crack tip solutions in non-linear ferroelectric materials

    E-print Network

    . Ferroelectric ceramics can exhibit non-linear and irreversible polarization and strain response to applied found in ferroelectric ceramics. Speci®cally, the constitutive behavior considered contains regionsUncoupled, asymptotic mode III and mode E crack tip solutions in non-linear ferroelectric materials

  3. Ferroelectric-Like Properties of Amorphous Metal Oxide Thin Films Prepared by Sol-Gel Technique

    Microsoft Academic Search

    Yuhuan Xu

    1995-01-01

    Advances in the field of both optical and electrical integrated circuit devices require new thin film materials. Ferroelectric materials have attractive properties such as hysteresis behavior, pyroelectricity, piezoelectricity and nonlinear optical properties. Many ferroelectric thin films have been successfully prepared from metal organic compounds via sol-gel processing. Thus far, research has concentrated upon polycrystalline or epitaxial ferroelectric films. For amorphous

  4. Electronic transitions and dielectric functions of relaxor ferroelectric Pb(In{sub 1?2}Nb{sub 1?2})O{sub 3}-Pb(Mg{sub 1?3}Nb{sub 2?3})O{sub 3}-PbTiO{sub 3} single crystals: Temperature dependent spectroscopic study

    SciTech Connect

    Zhu, J. J.; Zhang, J. Z.; Chu, J. H. [Key Laboratory of Polar Materials and Devices, Ministry of Education, Department of Electronic Engineering, East China Normal University, Shanghai 200241 (China); National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083 (China); Xu, G. S. [R and D Center of Synthetic Crystals, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 201800 (China); Zhang, X. L.; Hu, Z. G. [Key Laboratory of Polar Materials and Devices, Ministry of Education, Department of Electronic Engineering, East China Normal University, Shanghai 200241 (China)

    2014-03-31

    Optical properties and phase transitions of Pb(In{sub 1?2}Nb{sub 1?2})O{sub 3}-Pb(Mg{sub 1?3}Nb{sub 2?3})O{sub 3}-PbTiO{sub 3} (PIN-PMN-PT) crystals near morphotropic phase boundary (MPB) have been investigated by temperature dependent transmittance and reflectance spectra. Three critical point energies E{sub g}?=?3.17–3.18?eV, E{sub a}?=?3.41–3.61?eV, and E{sub b}?=?4.74–4.81?eV can be assigned to the transitions from oxygen 2p to titanium d, niobium d, and lead 6p states, respectively. They show narrowing trends with increasing temperature, which can be caused by thermal expansion of the lattice and electron-phonon interaction. Deviation from the linear behaviors can be observed from E{sub a} and E{sub b} versus PT concentration, indicating a complex multiphase structure near MPB region.

  5. Finite element analysis of cracks in ferroelectric ceramic materials

    Microsoft Academic Search

    W. Chen; C. S. Lynch

    1999-01-01

    A constitutive law governing the behavior of ferroelectric ceramics is presented. The constitutive law includes the effects of ferroelectric and ferroelastic polarization reorientation. It is both multiaxial and non-proportional. This material model is implemented in a finite element code developed for this work. The material model determines changes of remanent strain and remanent polarization induced by the stress and electric

  6. Constitutive relations of ferroelectric ceramics

    NASA Astrophysics Data System (ADS)

    Su, Yu

    The objective of this thesis is to obtain a better understanding on the fundamental constitutive behavior of ferroelectric ceramics based on the physics of phase transition, micromechanics of heterogeneous materials, and principles of irreversible thermodynamics. Within this framework, a self-consistent model is developed to investigate the electromechanical responses of ferroelectric polycrystals under temperature change and electromechanical loading. Cooling of a paraelectric crystal below its curie temperature Tc would result in spontaneous polarization, whereas electromechanical loading on a poled crystal could lead to domain switch. Domain growth and reorientation inside ferroelectric crystals are studied in light of these phase transition and domain switch. In this process, the change of the effective elastic, dielectric and piezoelectric constants during the evolution of microstructures are examined. In addition, hysteresis loops for the electric displacement and other related phenomena are computed under cyclic electric load. On top of all methods implemented in this work, the kinetic equation derived from the irreversible thermodynamics is the key to study the domain evolution in ferroelectric crystals. The kinetic relation not only governs the growth of new domain in a ferroelectric crystal, but it also determines the onset of phase transition. This characteristic is used to study the effect of hydrostatic pressure on the shift of Curie temperature of a ferroelectric crystal. Based on the derived expressions, it is observed that the deriving force can increase or decrease upon applied hydrostatic mechanical loading, depending on the change of electromechanical moduli, eigenstrain and electro-polarization. Several typical cases are computed and it is found that the change of the electromechanical moduli during phase transformation plays the key role in the shift of Curie temperature. Since ferroelectric ceramics are in a polycrystal form, a self-consistent model is used to examine the issues involved. In this model, each grain is represented by a spherical inclusion embedded in an infinitely extended piezoelectric matrix, and the inclusion further possesses an eigenstrain and eigen polarization. Secant relations between the polycrystal-matrix and the embedded inclusion are established by extending Hill's [1] incremental relations. An iterative computational program is developed for this self-consistent model.

  7. Possible ferroelectricity in perovskite oxynitride SrTaO2N epitaxial thin films

    PubMed Central

    Oka, Daichi; Hirose, Yasushi; Kamisaka, Hideyuki; Fukumura, Tomoteru; Sasa, Kimikazu; Ishii, Satoshi; Matsuzaki, Hiroyuki; Sato, Yukio; Ikuhara, Yuichi; Hasegawa, Tetsuya

    2014-01-01

    Compressively strained SrTaO2N thin films were epitaxially grown on SrTiO3 substrates using nitrogen plasma-assisted pulsed laser deposition. Piezoresponse force microscopy measurements revealed small domains (101–102?nm) that exhibited classical ferroelectricity, a behaviour not previously observed in perovskite oxynitrides. The surrounding matrix region exhibited relaxor ferroelectric-like behaviour, with remanent polarisation invoked by domain poling. First-principles calculations suggested that the small domains and the surrounding matrix had trans-type and a cis-type anion arrangements, respectively. These experiments demonstrate the promise of tailoring the functionality of perovskite oxynitrides by modifying the anion arrangements by using epitaxial strain.

  8. Modelling of the metal-ferroelectric metal capacitor: Part II - experimental verifications

    SciTech Connect

    Teowee, G. [Donnelly Corp., Tucson, AZ (United States); Uhlmann, D.R. [Univ. of Arizona, Tucson, AZ (United States)

    1994-12-31

    Metal-Ferroelectric-Metal structures, typified by Pt-PZT-Pt capacitors, are the basic building blocks for ferroelectric devices. The present paper offers experimental verification for PZT films of a proposed model based on totally depleted back-to-back Schottky barriers rather than partially depleted films. The presence of a built-in field within the PZT films can explain the ubiquitous higher values of coercive field in FE films compared with bulk ceramics, the asymmetry of hysteresis loops found in some FE films (due to uneven field distributions), the diffuse transition of dielectric constant with temperature near T{sub c}, and the much lower values of dielectric constant for relaxor FE films compared with values for bulk ceramics.

  9. Electric-field-, temperature-, and stress-induced phase transitions in relaxor ferroelectric single crystals

    Microsoft Academic Search

    Matthew Davis; Dragan Damjanovic; Nava Setter

    2006-01-01

    Electric-field-induced phase transitions have been evidenced by macroscopic strain measurements at temperatures between 25°C and 100°C in [001]C -poled (1-x)Pb(Mg1\\/3Nb2\\/3)O3-xPbTiO3[(PMN-xPT);x=0.25,0.305,0.31] and (1-x)Pb(Zn1\\/3Nb2\\/3)O3-xPbTiO3[(PZN-xPT);x=0.05,0.065,0.085] single crystals. Such measurements provide a convenient way of ascertaining thermal and electrical phase stabilities over a range of compositions and give direct evidence for first-order phase transitions. A pseudorhombohedral (MA) -pseudo-orthorhombic (MC) -tetragonal (T) polarization rotation path

  10. 25 pyrochlore relaxor ferroelectric Cd2Nb2O7 and its Fe2

    E-print Network

    Paris-Sud XI, Université de

    The weak-field dielectric dispersion 100 Hz­1.8 GHz studies both of pure and Fe2 /Fe3 modified Cd2Nb2O7 temperature of the zero-field-cooled state (Tf 183 K) the dielectric absorption spectra and the relaxation.8 GHz observed both in Cd2Nb2O7 and its isostructural analog Cd2Ta2O7 at RT and higher a centrosymmetric

  11. Energy harvesting based on Ericsson pyroelectric cycles in a relaxor ferroelectric ceramic

    NASA Astrophysics Data System (ADS)

    Sebald, Gael; Pruvost, Sebastien; Guyomar, Daniel

    2008-02-01

    This work deals with energy harvesting from temperature variations. It is shown here that direct pyroelectric energy harvesting (connecting an adapted resistance, for example) is not effective, whereas Ericsson-based cycles give energy 100 times higher. The principle and experimental validation of the Ericsson cycle are shown with the example of 0.90Pb(Mg1/3Nb2/3)O3-0.10PbTiO3 ceramic. Harvested energy reached 186 mJ cm-3 for 50 °C temperature variation and electric field cycle of 3.5 kV mm-1. A correlation between the electrocaloric effect and pyroelectric energy harvesting is then shown. Harvested electric energy with Ericsson cycles can be simply expressed as electrocaloric heat multiplied by Carnot efficiency. Several examples are then given from materials with the highest known electrocaloric effect. This leads to energies of hundreds of mJ cm-3 for a limited 10 °C temperature variation. Compared to Carnot's efficiency, this is much higher than the best thermoelectric materials based on the Seebeck effect.

  12. Large Displacement in Relaxor Ferroelectric Terpolymer Blend Derived Actuators Using Al Electrode for Braille Displays

    PubMed Central

    Lu, S. G.; Chen, X.; Levard, T.; Diglio, P. J.; Gorny, L. J.; Rahn, C. D.; Zhang, Q. M.

    2015-01-01

    Poly(vinylidene fluoride) (PVDF) based polymers are attractive for applications for artificial muscles, high energy density storage devices etc. Recently these polymers have been found great potential for being used as actuators for refreshable full-page Braille displays for visually impaired people in terms of light weight, miniaturized size, and larger displacement, compared with currently used lead zirconate titanate ceramic actuators. The applied voltages of published polymer actuators, however, cannot be reduced to meet the requirements of using city power. Here, we report the polymer actuator generating quite large displacement and blocking force at a voltage close to the city power. Our embodiments also show good self-healing performance and disuse of lead-containing material, which makes the Braille device safer, more reliable and more environment-friendly. PMID:26079628

  13. Large Displacement in Relaxor Ferroelectric Terpolymer Blend Derived Actuators Using Al Electrode for Braille Displays.

    PubMed

    Lu, S G; Chen, X; Levard, T; Diglio, P J; Gorny, L J; Rahn, C D; Zhang, Q M

    2015-01-01

    Poly(vinylidene fluoride) (PVDF) based polymers are attractive for applications for artificial muscles, high energy density storage devices etc. Recently these polymers have been found great potential for being used as actuators for refreshable full-page Braille displays for visually impaired people in terms of light weight, miniaturized size, and larger displacement, compared with currently used lead zirconate titanate ceramic actuators. The applied voltages of published polymer actuators, however, cannot be reduced to meet the requirements of using city power. Here, we report the polymer actuator generating quite large displacement and blocking force at a voltage close to the city power. Our embodiments also show good self-healing performance and disuse of lead-containing material, which makes the Braille device safer, more reliable and more environment-friendly. PMID:26079628

  14. Effect of halogen atom exchange on the thermodynamic behavior and ferroelectric properties of [C(NH2)3]4Br2SO4

    NASA Astrophysics Data System (ADS)

    Szafra?ski, Marek; Katrusiak, Andrzej

    2006-04-01

    A new ferroelectric, [C(NH2)3]4Br2SO4 , has been characterized by dielectric, calorimetric and dilatometric methods, and its paraelectric and ferroelectric structures determined by x-ray diffraction. The crystal undergoes the first-order ferroelectric-paraelectric phase transition at TC=365.5K . The transition is driven by disordering of the SO42- anions, but the spontaneous polarization originates essentially from the ionic displacements. The temperature dependence of the order parameter is well described by Landau’s mean-field approximation. By comparing with [C(NH2)3]4Cl2SO4 crystal it has been shown that the Br/Cl halogen atom exchange caused the anisotropic deformation of the crystal lattice modifying the ionic and hydrogen-bond interactions, resulting in the upward shift of the Curie point, the essential changes in the crystal phase diagram, and modified ferroelectric properties. Although the paraelectric phases of [C(NH2)3]4Cl2SO4 and [C(NH2)3]4Br2SO4 are isostructural in tetragonal space groups I4¯2m , below TC the first one becomes a two-directional ferroelectric in space group Cmc21 , while the second one a one-directional ferroelectric in space group Fmm2 . The room-temperature ferroelectricity, and the high piezoelectric response and large electric field-switchable strain, revealed in [C(NH2)3]4Br2SO4 , can be useful for electronic applications.

  15. Ferroelectric mobile water.

    PubMed

    Nakamura, Yoshimichi; Ohno, Takahisa

    2011-01-21

    In molecular dynamics simulations single-domain ferroelectric water is produced under ordinary ambient conditions utilizing carbon nanotubes open to a water reservoir. This ferroelectric water diffuses while keeping its proton-ordered network intact. The mobile/immobile water transitions and the step-wise changes in net polarization of water are observed to occur spontaneously. The immobile water becomes mobile by transforming into the single-domain ferroelectric water. Our general notion of relating a more highly ordered structure with a lower temperature has so far restricted researchers' attention to very low temperatures when experimenting on proton-ordered phases of water. The present study improves our general understanding of water, considering that the term 'ferroelectric water' has so far practically stood for 'ferroelectric ice,' and that single-domain ferroelectric water has not been reported even for the ice nanotubes. PMID:21072393

  16. Ferroelectric and Magnetodielectric Properties of Cobalt-Doped Sr x Ba1-x Nb2O6 Ceramics

    NASA Astrophysics Data System (ADS)

    Kshirsagar, S. H.; Tarale, A. N.; Jigajeni, S. R.; Salunkhe, D. J.; Kulkarni, S. B.; Joshi, P. B.

    2015-04-01

    Relaxor ferroelectrics Sr0.5Ba0.5Nb2O6 (SBN50) and Sr0.4Ba0.6Nb2O6 (SBN40), both pure and cobalt (Co) doped, have been synthesized and investigated to understand possible interaction between magnetic and electric order parameters. Synthesis was carried out via ceramic route. This paper reports the synthesis, crystal structure, dielectric properties, P-E hysteresis loops, M-H hysteresis loops, and magnetocapacitance (M c) of the Co-doped SBN compositions. All compositions were observed to exhibit useful values of M c, especially at frequencies less than 10 kHz.

  17. Ferroelectric and Magnetodielectric Properties of Cobalt-Doped Sr x Ba1- x Nb2O6 Ceramics

    NASA Astrophysics Data System (ADS)

    Kshirsagar, S. H.; Tarale, A. N.; Jigajeni, S. R.; Salunkhe, D. J.; Kulkarni, S. B.; Joshi, P. B.

    2015-07-01

    Relaxor ferroelectrics Sr0.5Ba0.5Nb2O6 (SBN50) and Sr0.4Ba0.6Nb2O6 (SBN40), both pure and cobalt (Co) doped, have been synthesized and investigated to understand possible interaction between magnetic and electric order parameters. Synthesis was carried out via ceramic route. This paper reports the synthesis, crystal structure, dielectric properties, P- E hysteresis loops, M- H hysteresis loops, and magnetocapacitance ( M c) of the Co-doped SBN compositions. All compositions were observed to exhibit useful values of M c, especially at frequencies less than 10 kHz.

  18. JOURNAL OF MATERIALS SCIENCE LETTERS 18 (1999) 1025 1027 Fatigue crack growth in ferroelectric ceramics below the coercive field

    E-print Network

    Zhu, Ting

    1999-01-01

    -dem@mail.tsinghua.edu.cn Perovskite-type ferroelectric ceramics have found many applications in actuators, sensors and memories. One in the devices [2]. It is essen- tial to characterize the failure behavior of ferroelectric ceramics whenJOURNAL OF MATERIALS SCIENCE LETTERS 18 (1999) 1025­ 1027 Fatigue crack growth in ferroelectric

  19. Interplay of Coulomb blockade and ferroelectricity in nanosized granular materials

    NASA Astrophysics Data System (ADS)

    Udalov, O. G.; Chtchelkatchev, N. M.; Glatz, A.; Beloborodov, I. S.

    2014-02-01

    We study electron transport properties of composite ferroelectrics—materials consisting of metallic grains embedded in a ferroelectric matrix. In particular, we calculate the conductivity in a wide range of temperatures and electric fields, showing pronounced hysteretic behavior. In weak fields, electron cotunneling is the main transport mechanism. In this case, we show that the ferroelectric matrix strongly influences the transport properties through two effects: (i) the dependence of the Coulomb gap on the dielectric permittivity of the ferroelectric matrix, which in turn is controlled by temperature and external field, and (ii) the dependence of the tunneling matrix elements on the electric polarization of the ferroelectric matrix, which can be tuned by temperature and applied electric field as well. In the case of strong electric fields, the Coulomb gap is suppressed and only the second mechanism is important. Our results are important for (i) thermometers for precise temperature measurements and (ii) ferrroelectric memristors.

  20. Semiconductor/relaxor 0-3 type composites without thermal depolarization in Bi?.?Na?.?TiO?-based lead-free piezoceramics.

    PubMed

    Zhang, Ji; Pan, Zhao; Guo, Fei-Fei; Liu, Wen-Chao; Ning, Huanpo; Chen, Y B; Lu, Ming-Hui; Yang, Bin; Chen, Jun; Zhang, Shan-Tao; Xing, Xianran; Rödel, Jürgen; Cao, Wenwu; Chen, Yan-Feng

    2015-01-01

    Commercial lead-based piezoelectric materials raised worldwide environmental concerns in the past decade. Bi?.?Na?.?TiO?-based solid solution is among the most promising lead-free piezoelectric candidates; however, depolarization of these solid solutions is a longstanding obstacle for their practical applications. Here we use a strategy to defer the thermal depolarization, even render depolarization-free Bi?.?Na?.?TiO?-based 0-3-type composites. This is achieved by introducing semiconducting ZnO particles into the relaxor ferroelectric 0.94Bi?.?Na?.?TiO?-0.06BaTiO? matrix. The depolarization temperature increases with increasing ZnO concentration until depolarization disappears at 30 mol% ZnO. The semiconducting nature of ZnO provides charges to partially compensate the ferroelectric depolarization field. These results not only pave the way for applications of Bi?.?Na?.?TiO?-based piezoceramics, but also have great impact on the understanding of the mechanism of depolarization so as to provide a new design to optimize the performance of lead-free piezoelectrics. PMID:25790446

  1. Effect of kinetic growth parameters on leakage current and ferroelectric behavior of BiFeO3 thin films

    NASA Astrophysics Data System (ADS)

    Shelke, Vilas; Harshan, V. N.; Kotru, Sushma; Gupta, Arunava

    2009-11-01

    Epitaxial BiFeO3 thin films have been grown on (100)-oriented SrTiO3 and Nb-doped SrTiO3 substrates using the pulsed laser deposition technique under identical thermodynamic and variable kinetic conditions. The variation of growth kinetics through laser fluence and pulse repetition rate had minimal effect on the structure and magnetic properties of films. However, large changes were observed in the microstructure, with initial island growth mode approaching toward step-flow type growth and roughness reducing from 12.5 to 1.8 nm for 50 nm thick film. Correspondingly, the leakage current density at room temperature dropped consistently by almost four orders of magnitude. The dominant mechanism in low leakage current films was space-charge-limited conduction. These findings suggest that the issue of leakage current can be dealt favorably by controlling kinetic growth parameters. The application of high electric field and observation of maximum polarization value up to 103 ?C/cm2 could be possible in these samples. An appearance of saturated hysteresis behavior depending upon bottom electrode was also observed. This fact is qualitatively explained on the basis of recent concepts of switchability and polarity of thin film-electrode interface.

  2. Soft-mode behavior and incipient ferroelectricity in Na1/2Bi1/2Cu3Ti4O12

    NASA Astrophysics Data System (ADS)

    Ferrarelli, Matthew C.; Nuzhnyy, Dmitry; Sinclair, Derek C.; Kamba, Stanislav

    2010-06-01

    The correlation between crystal structure and intrinsic dielectric properties of the unusual cubic perovskite-related family of compounds ACu3Ti4O12 , where A=Ca , Cd, La2/3 , Bi2/3 , Na1/2La1/2 , Na1/2Bi1/2 , etc., (space group Im3¯ ) has been a controversial topic for several years, especially for the most studied member of the family CaCu3Ti4O12 (CCTO). Na1/2Bi1/2Cu3Ti4O12 (NBCTO) is isostructural with CCTO and retains centrosymmetric and cubic symmetry (space group Im3¯ ) down to 4 K. NBCTO ceramics exhibit high intrinsic relative permittivity of ˜145 at 300 K that rises on cooling and levels off below ˜50K with a value of ˜260 at 10 K without any signature of a structural transition. Such behavior is a typical feature of incipient ferroelectrics such as the perovskite CaTiO3 . Infrared and terahertz spectroscopy on NBCTO ceramics are presented and reveal a room-temperature soft polar optic mode at ˜34cm-1 that softens on cooling and is responsible for the temperature dependence of the relative permittivity. The temperature dependence of the soft-mode frequency obeys the Barrett formula with the onset of quantum fluctuations T1 occurring near 85 K and a hypothetical Curie temperature T0 of ˜-155K . A fitted vibrational zero-point energy (kBT1)/2 is in good agreement with the measured soft-mode frequency. The crystal structure-intrinsic dielectric properties of NBCTO and possibly all cubic ACu3Ti4O12 phases are, therefore, consistent with that of other untilted/tilted TiO3 -based centrosymmetric perovskites such as CaTiO3 and SrTiO3 . The “so-called” giant permittivity values of >1000 reported for CCTO, NBCTO, and related phases from radio-frequency capacitance measurements near room temperature are an extrinsic effect associated with the semiconducting nature of these materials, as opposed to an intrinsic effect associated with their rather unusual perovskite-type crystal structure.

  3. Quantum mechanical studies of complex ferroelectric perovskites

    NASA Astrophysics Data System (ADS)

    Ramer, Nicholas John

    In many electronic device applications, there is a need to interconvert electrical energy and other types of energy. Ferroelectric materials, which possess a voltage-dependent polarization, can enable this energy conversion process. Because of the broad interest in ferroelectric materials for these devices, there is a critical research effort, both experimental and theoretical, to understand these materials and aid in the development of materials with improved properties. This thesis presents detailed quantum mechanical investigations of the behavior of a complex ferroelectric perovskite under applied stress. In particular, we have chosen to study the solid solution PbZr1-xTix O3 (PZT). Since the study of ferroelectricity involves understanding both its structural and electronic signatures in materials, it has necessitated the development of a novel theoretical technique which improves the accuracy of the pseudopotentials used in our density functional theory calculations as well as a new method for constructing three-dimensional atomistic responses to small amounts of external stress. To examine the material's behavior under larger amounts of stress, we have studied the behavior of a composition of PZT lying near a structural phase boundary. On either side of the phase boundary, the material is characterized by a different polarization direction and may easily be switched between phases by applying external stress. In addition to stress-induced phase transitions, most ferroelectric materials also have composition dependent phase boundaries. Since different compositions of PZT would require increased computational effort, we have formulated an improved virtual crystal approach that makes tractable the study of the entire composition range. Using this method, we have been able to show for the first time via first-principles calculations, a composition dependent phase transition in a ferroelectric material. This thesis has accomplished three important goals: new theoretical methodology has been developed to enable accurate modeling of complex materials; application of these methods has been demonstrated for the study of ferroelectric oxides; and these investigations have revealed new insights into the relationships between stress, chemical composition, and ferroelectricity in oxides. This set of accomplishments enables the future study of even more complex perovskites and other multi-component systems.

  4. Ferroelectric switching of elastin

    PubMed Central

    Liu, Yuanming; Cai, Hong-Ling; Zelisko, Matthew; Wang, Yunjie; Sun, Jinglan; Yan, Fei; Ma, Feiyue; Wang, Peiqi; Chen, Qian Nataly; Zheng, Hairong; Meng, Xiangjian; Sharma, Pradeep; Zhang, Yanhang; Li, Jiangyu

    2014-01-01

    Ferroelectricity has long been speculated to have important biological functions, although its very existence in biology has never been firmly established. Here, we present compelling evidence that elastin, the key ECM protein found in connective tissues, is ferroelectric, and we elucidate the molecular mechanism of its switching. Nanoscale piezoresponse force microscopy and macroscopic pyroelectric measurements both show that elastin retains ferroelectricity at 473 K, with polarization on the order of 1 ?C/cm2, whereas coarse-grained molecular dynamics simulations predict similar polarization with a Curie temperature of 580 K, which is higher than most synthetic molecular ferroelectrics. The polarization of elastin is found to be intrinsic in tropoelastin at the monomer level, analogous to the unit cell level polarization in classical perovskite ferroelectrics, and it switches via thermally activated cooperative rotation of dipoles. Our study sheds light onto a long-standing question on ferroelectric switching in biology and establishes ferroelectricity as an important biophysical property of proteins. This is a critical first step toward resolving its physiological significance and pathological implications. PMID:24958890

  5. Ferroelectric switching of elastin.

    PubMed

    Liu, Yuanming; Cai, Hong-Ling; Zelisko, Matthew; Wang, Yunjie; Sun, Jinglan; Yan, Fei; Ma, Feiyue; Wang, Peiqi; Chen, Qian Nataly; Zheng, Hairong; Meng, Xiangjian; Sharma, Pradeep; Zhang, Yanhang; Li, Jiangyu

    2014-07-01

    Ferroelectricity has long been speculated to have important biological functions, although its very existence in biology has never been firmly established. Here, we present compelling evidence that elastin, the key ECM protein found in connective tissues, is ferroelectric, and we elucidate the molecular mechanism of its switching. Nanoscale piezoresponse force microscopy and macroscopic pyroelectric measurements both show that elastin retains ferroelectricity at 473 K, with polarization on the order of 1 ?C/cm(2), whereas coarse-grained molecular dynamics simulations predict similar polarization with a Curie temperature of 580 K, which is higher than most synthetic molecular ferroelectrics. The polarization of elastin is found to be intrinsic in tropoelastin at the monomer level, analogous to the unit cell level polarization in classical perovskite ferroelectrics, and it switches via thermally activated cooperative rotation of dipoles. Our study sheds light onto a long-standing question on ferroelectric switching in biology and establishes ferroelectricity as an important biophysical property of proteins. This is a critical first step toward resolving its physiological significance and pathological implications. PMID:24958890

  6. Ferroelectric properties in Mn-modified BiFeO3-BaTiO3 ceramics

    NASA Astrophysics Data System (ADS)

    Dai, Zhonghua; Akishige, Yukikuni

    2014-12-01

    Multiferroic 0.4 mol%-MnO2-doped 0.78BiFeO3-0.22BaTiO3 ceramics were prepared by a traditional ceramic process. The effects of doping and annealing on the dielectric and ferroelectric properties were intensively investigated. Dielectric dispersion like relaxor ferroelectrics was observed in the oxygen annealed sample, but disappeared in the vacuum annealed sample. Modification of the BiFeO3-BaTiO3 with MnO2 and annealing in vacuum improved DC resistivity obviously. The spontaneous polarization, remnant polarization, and coercive field are 65.2 ?C/cm2, 59.5 ?C/cm2 and 21.9 kV/cm, respectively under an applied field of 35 kV/cm.

  7. FERROELECTRICS Editorial Recent developments in ferroelectric nanostructures

    E-print Network

    Alpay, S. Pamir

    -film deposition and nanoscale fabrication techniques made over the past two decades have created new possibilities a sub-group of functional (or smart) materials whose physical properties are sensitive to changes-film memories. Because of their strongly non-linear dielectric response ferroelectrics can be utilized

  8. Ferroelectric Light Control Device

    NASA Technical Reports Server (NTRS)

    Park, Yeonjoon (Inventor); Choi, Sang H. (Inventor); King, Glen C. (Inventor); Kim, Jae-Woo (Inventor); Elliott, Jr., James R. (Inventor)

    2008-01-01

    A light control device is formed by ferroelectric material and N electrodes positioned adjacent thereto to define an N-sided regular polygonal region or circular region there between where N is a multiple of four.

  9. Ferroelectric domain wall injection.

    PubMed

    Whyte, Jonathan R; McQuaid, Raymond G P; Sharma, Pankaj; Canalias, Carlota; Scott, James F; Gruverman, Alexei; Gregg, J Marty

    2014-01-15

    Ferroelectric domain wall injection has been demonstrated by engineering of the local electric field, using focused ion beam milled defects in thin single crystal lamellae of KTiOPO4 (KTP). The electric field distribution (top) displays localized field hot-spots, which correlate with nucleation events (bottom). Designed local field variations can also dictate subsequent domain wall mobility, demonstrating a new paradigm in ferroelectric domain wall control. PMID:24136810

  10. Electrical characterization and equivalent circuit analysis of (Bi1.5Zn0.5)(Nb0.5Ti1.5)O7 Pyrochlore, a relaxor ceramic

    NASA Astrophysics Data System (ADS)

    Osman, Rozana A. M.; West, Anthony R.

    2011-04-01

    The ac impedance of (Bi1.5Zn0.5)(Nb0.5Ti1.5)O7, a relaxor ceramic with the pyrochlore structure, has been measured over the temperature range 10-1073 K and analyzed using a combination of traditional, fixed-frequency sweeps of permittivity and tan ?, impedance analysis using resistance-capacitance (RC) circuit combinations and equivalent circuit modeling with the inclusion of a constant phase element (CPE). Low temperature data accurately fit an equivalent circuit containing a parallel R-C-CPE element in series with a capacitor. From the temperature-dependence of the fitted R,C,CPE parameters, a model for the relaxor behavior is obtained.

  11. Coexistence of ergodicity and nonergodicity in LaFeO3-modified Bi(1/2)(Na(0.78)K(0.22))(1/2)TiO3 relaxors.

    PubMed

    Han, Hyoung-Su; Jo, Wook; Rödel, Jürgen; Hong, In-Ki; Tai, Weon-Pil; Lee, Jae-Shin

    2012-09-12

    The effect of LaFeO(3) addition to Bi(1/2)(Na(0.78)K(0.22))(1/2)TiO(3) ceramics on the phase stability and macroscopic functional properties was investigated. Similarly to other chemical modifiers known in the literature, LaFeO(3) addition suppresses an electric-field-induced long-range ferroelectric order, giving rise to a giant unipolar strain of ~0.3% at 2 mol% LaFeO(3) addition. Time-dependent changes in polarization and strain hysteresis loops both during successive electrical cycling and after removal of the electric field suggest that a specimen with 2 mol% LaFeO(3) consists of both ergodic and nonergodic phases, which is unique among the known relaxor materials. PMID:22907150

  12. Continuously-tuned tunneling behaviors of ferroelectric tunnel junctions based on BaTiO{sub 3}/La{sub 0.67}Sr{sub 0.33}MnO{sub 3} heterostructure

    SciTech Connect

    Ou, Xin; Xu, Bo, E-mail: xubonju@gmail.com; Yin, Qiaonan; Xia, Yidong; Yin, Jiang; Liu, Zhiguo [National Laboratory of Solid State Microstructures and Department of Materials Science and Engineering, Nanjing University, Nanjing 210093 (China)] [National Laboratory of Solid State Microstructures and Department of Materials Science and Engineering, Nanjing University, Nanjing 210093 (China); Gong, Changjie; Lan, Xuexin [National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093 (China)] [National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093 (China)

    2014-05-15

    In this work, we fabricate BaTiO{sub 3}/La{sub 0.67}Sr{sub 0.33}MnO{sub 3} (BTO/LSMO) ferroelectric tunnel junction on (001) SrTiO{sub 3} substrate by pulsed laser deposition method. Combining piezoresponse force and conductive-tip atomic force microscopy, we demonstrate robust and reproducible polarization-controlled tunneling behaviors with the resulting tunneling electroresistance value reaching about 10{sup 2} in ultrathin BTO films (?1.2 nm) at room temperature. Moreover, local poling areas with different conductivity are finally achieved by controlling the relative proportion of upward and downward domains, and different poling areas exhibit stable transport properties.

  13. Room temperature ferromagnetism and ferroelectricity behavior of (Cu, Li) co-doped ZnO films deposited by reactive magnetron sputtering

    Microsoft Academic Search

    C. W. Zou; H. J. Wang; M. L. Yin; M. Li; C. S. Liu; L. P. Guo; D. J. Fu; T. W. Kang

    2010-01-01

    Single-phase Zn0.95?xCuxLi0.05O thin films have been prepared on Pt (111)\\/Ti\\/SiO2 substrates by reactive magnetron sputtering method. The XRD, XPS and absorption measurements confirmed the polycrystalline nature of the films and the substitution of Zn2+ by Cu2+ ions. The sputtered Zn0.90Cu0.05Li0.05O film shows multiferroic properties exhibiting a saturated ferroelectric loop with a remanent polarization of 6?C\\/cm2 and a saturated loop with

  14. Giant Electroresistive Ferroelectric Diode on 2DEG

    PubMed Central

    Kim, Shin-Ik; Jin Gwon, Hyo; Kim, Dai-Hong; Keun Kim, Seong; Choi, Ji-Won; Yoon, Seok-Jin; Jung Chang, Hye; Kang, Chong-Yun; Kwon, Beomjin; Bark, Chung-Wung; Hong, Seong-Hyeon; Kim, Jin-Sang; Baek, Seung-Hyub

    2015-01-01

    Manipulation of electrons in a solid through transmitting, storing, and switching is the fundamental basis for the microelectronic devices. Recently, the electroresistance effect in the ferroelectric capacitors has provided a novel way to modulate the electron transport by polarization reversal. Here, we demonstrate a giant electroresistive ferroelectric diode integrating a ferroelectric capacitor into two-dimensional electron gas (2DEG) at oxide interface. As a model system, we fabricate an epitaxial Au/Pb(Zr0.2Ti0.8)O3/LaAlO3/SrTiO3 heterostructure, where 2DEG is formed at LaAlO3/SrTiO3 interface. This device functions as a two-terminal, non-volatile memory of 1 diode-1 resistor with a large I+/I? ratio (>108 at ±6?V) and Ion/Ioff ratio (>107). This is attributed to not only Schottky barrier modulation at metal/ferroelectric interface by polarization reversal but also the field-effect metal-insulator transition of 2DEG. Moreover, using this heterostructure, we can demonstrate a memristive behavior for an artificial synapse memory, where the resistance can be continuously tuned by partial polarization switching, and the electrons are only unidirectionally transmitted. Beyond non-volatile memory and logic devices, our results will provide new opportunities to emerging electronic devices such as multifunctional nanoelectronics and neuromorphic electronics. PMID:26014446

  15. Giant Electroresistive Ferroelectric Diode on 2DEG.

    PubMed

    Kim, Shin-Ik; Jin Gwon, Hyo; Kim, Dai-Hong; Keun Kim, Seong; Choi, Ji-Won; Yoon, Seok-Jin; Jung Chang, Hye; Kang, Chong-Yun; Kwon, Beomjin; Bark, Chung-Wung; Hong, Seong-Hyeon; Kim, Jin-Sang; Baek, Seung-Hyub

    2015-01-01

    Manipulation of electrons in a solid through transmitting, storing, and switching is the fundamental basis for the microelectronic devices. Recently, the electroresistance effect in the ferroelectric capacitors has provided a novel way to modulate the electron transport by polarization reversal. Here, we demonstrate a giant electroresistive ferroelectric diode integrating a ferroelectric capacitor into two-dimensional electron gas (2DEG) at oxide interface. As a model system, we fabricate an epitaxial Au/Pb(Zr0.2Ti0.8)O3/LaAlO3/SrTiO3 heterostructure, where 2DEG is formed at LaAlO3/SrTiO3 interface. This device functions as a two-terminal, non-volatile memory of 1 diode-1 resistor with a large I+/I- ratio (>10(8) at ±6?V) and Ion/Ioff ratio (>10(7)). This is attributed to not only Schottky barrier modulation at metal/ferroelectric interface by polarization reversal but also the field-effect metal-insulator transition of 2DEG. Moreover, using this heterostructure, we can demonstrate a memristive behavior for an artificial synapse memory, where the resistance can be continuously tuned by partial polarization switching, and the electrons are only unidirectionally transmitted. Beyond non-volatile memory and logic devices, our results will provide new opportunities to emerging electronic devices such as multifunctional nanoelectronics and neuromorphic electronics. PMID:26014446

  16. Polarization fatigue of organic ferroelectric capacitors

    PubMed Central

    Zhao, Dong; Katsouras, Ilias; Li, Mengyuan; Asadi, Kamal; Tsurumi, Junto; Glasser, Gunnar; Takeya, Jun; Blom, Paul W. M.; de Leeuw, Dago M.

    2014-01-01

    The polarization of the ferroelectric polymer P(VDF-TrFE) decreases upon prolonged cycling. Understanding of this fatigue behavior is of great technological importance for the implementation of P(VDF-TrFE) in random-access memories. However, the origin of fatigue is still ambiguous. Here we investigate fatigue in thin-film capacitors by systematically varying the frequency and amplitude of the driving waveform. We show that the fatigue is due to delamination of the top electrode. The origin is accumulation of gases, expelled from the capacitor, under the impermeable top electrode. The gases are formed by electron-induced phase decomposition of P(VDF-TrFE), similar as reported for inorganic ferroelectric materials. When the gas barrier is removed and the waveform is adapted, a fatigue-free ferroelectric capacitor based on P(VDF-TrFE) is realized. The capacitor can be cycled for more than 108 times, approaching the programming cycle endurance of its inorganic ferroelectric counterparts. PMID:24861542

  17. Time-Resolved, Electric-Field-Induced Domain Switching and Strain in Ferroelectric Ceramics and Crystals

    NASA Astrophysics Data System (ADS)

    Jones, Jacob L.; Nino, Juan C.; Pramanick, Abhijit; Daniels, John E.

    Ferroelectric materials are used in a variety of applications including diagnostic and therapeutic ultrasound, sonar, vibration and displacement sensors, and non-volatile random access memory. The electromechanical response in ferroelectric materials is comprised of both intrinsic (piezoelectric lattice strain) and extrinsic (e.g., domain wall motion) components that are expressed as characteristic changes in the diffraction pattern. By applying slow, step-wise changes in the electric field, prior quasi-dynamic diffraction measurements have demonstrated both lattice strains and non-180 ? domain switching at fields exceeding the macroscopically defined coercive field. However, the loading conditions which most replicate real device operation involve dynamic actuation with sub-coercive, cyclic electric fields. At these operating conditions, extrinsic irreversibilities lead to hysteresis, frequency dispersion and nonlinearity of macroscopic properties. Observation of strain and domain switching at these cyclic loading conditions is an area in which we have reported recent advances using stroboscopic techniques. This chapter highlights the electric-field-induced lattice strain and kinetics of domain switching in a number of materials including technologically-relevant lead zirconate titanate (PZT) ceramics and relaxor single crystals. An outlook on the continuing use of time-resolved diffraction techniques in the characterization of ferroelectric materials is also discussed.

  18. Depolarization field effect on dielectric and piezoelectric properties of particulate ferroelectric ceramic-polymer composites

    NASA Astrophysics Data System (ADS)

    Ma, Fengde D.; Wang, Yu U.

    2015-03-01

    The effects of depolarization field on the dielectric and piezoelectric properties of ferroelectric ceramic particle-filled polymer-matrix composites are investigated at the underlying domain level. Phase field modeling and simulation reveals that the macroscopic properties of the composites are dominated by depolarization field effect, which depends on the arrangement and alignment rather than the size or internal grain structure of the ferroelectric particulates. It is found that 0-3 particulate composites with random dispersion of ferroelectric particles behave essentially like linear dielectric rather than ferroelectric materials, and domain-level analysis reveals the physical mechanism for lack of domain switching or hysteresis as attributed to strong depolarization effect. Thus, without effective reduction or elimination of the depolarization field, the composites cannot benefit from the functional fillers regardless of their superior properties. In order to exhibit the desired ferroelectric behaviors, it necessitates continuous ferroelectric phase connectivity in the composites.

  19. On the Development of Multiaxial Phenomenological Constitutive Laws for Ferroelectric Ceramics

    Microsoft Academic Search

    Christopher S. Lynch

    1998-01-01

    Multiaxial constitutive laws for ferroelectric ceramics that include hysteresis, rate dependence, saturation, and are capable of simulating nonproportional loading are needed for stress analysis and reliable design of smart structures. The relationship between constitutive behavior of ferroelectric ceramics and phenomena that occur across multiple length scales is reviewed. A framework for the development of phenomenological constitutive laws at the macroscopic

  20. A ferroelectric memristor

    NASA Astrophysics Data System (ADS)

    Chanthbouala, André; Garcia, Vincent; Cherifi, Ryan O.; Bouzehouane, Karim; Fusil, Stéphane; Moya, Xavier; Xavier, Stéphane; Yamada, Hiroyuki; Deranlot, Cyrile; Mathur, Neil D.; Bibes, Manuel; Barthélémy, Agnès; Grollier, Julie

    2012-10-01

    Memristors are continuously tunable resistors that emulate biological synapses. Conceptualized in the 1970s, they traditionally operate by voltage-induced displacements of matter, although the details of the mechanism remain under debate. Purely electronic memristors based on well-established physical phenomena with albeit modest resistance changes have also emerged. Here we demonstrate that voltage-controlled domain configurations in ferroelectric tunnel barriers yield memristive behaviour with resistance variations exceeding two orders of magnitude and a 10?ns operation speed. Using models of ferroelectric-domain nucleation and growth, we explain the quasi-continuous resistance variations and derive a simple analytical expression for the memristive effect. Our results suggest new opportunities for ferroelectrics as the hardware basis of future neuromorphic computational architectures.

  1. Magnetic and magnetoelectric properties of nickel ferrite–lead iron niobate relaxor composites

    Microsoft Academic Search

    P. Guzdek; M. Sikora; ?. Góra; Cz. Kapusta

    Magnetoelectric effect in bulk ceramic and multilayer (laminated) structures consisting of 6 nickel ferrite and 7 lead iron niobate relaxor (PFN) layers was investigated. This paper describes the synthesis and tape-casting process for ferrimagnetic Ni0.3Zn0.62Cu0.08Fe2O4 ferrite and multiferroic relaxor Pb(Fe0.5Nb0.5)O3. X-ray analysis and studies of the electrical and magnetic properties were performed for bulk and layered composites. Complex impedance and

  2. Complex structural-ferroelectric domain walls in thin films of hexagonal orthoferrites RFeO3 (R = Lu, Er)

    NASA Astrophysics Data System (ADS)

    Roddatis, Vladimir V.; Akbashev, Andrew R.; Lopatin, Sergei; Kaul, Andrey R.

    2013-09-01

    Hexagonal orthoferrites have recently attracted much attention as possible high-temperature ferromagnetic ferroelectrics. The ferroelectric domain structure of hexagonal RMnO3, their antiferromagnetic structural analogies, has recently shown an atypical and complicated behavior. Hexagonal RFeO3 are expected to exhibit similar domain structure that should coexist with weak ferromagnetic order and may represent a material with a unusual magnetoelectric interaction. In this report, we discuss microscopic ferroelectric domain structure of hexagonal orthoferrites in a thin-film state and demonstrate a distinct and unusual improper ferroelectric behavior of these oxide materials.

  3. Ferroelectric-gated terahertz plasmonics on graphene

    E-print Network

    Jin, Dafei

    Inspired by recent advancement of ferroelectric-gated memories and transistors, we propose a design of ferroelectric-gated nanoplasmonic devices based on graphene sheets clamped in ferroelectric crystals. We show that the ...

  4. Study of physical properties of integrated ferroelectric/ferromagnetic heterostructures

    SciTech Connect

    Martinez, R.; Kumar, A. [Department of Physics, University of Puerto Rico, Puerto Rico 00931-3343 (United States); Palai, R.; Katiyar, R. S. [Department of Physics, University of Puerto Rico, Puerto Rico 00931-3343 (United States); Institute for Functional Nanomaterials, University of Puerto Rico, Puerto Rico 00931-3343 (United States); Scott, J. F. [Cavendish Laboratory, Department of Physics, Cambridge University, Cambridge CB3 0HE (United Kingdom)

    2010-06-15

    Superlattices (SLs) with different periodicity of ferromagnetic La{sub 0.7}Sr{sub 0.3}MnO{sub 3} (LSMO) and ferroelectric Ba{sub 0.7}Sr{sub 0.3}TiO{sub 3} as constitutive layers were fabricated on conducting LaNiO{sub 3} coated (001) oriented MgO substrates using pulsed laser deposition. The crystallinity, ferroelectric, and magnetic properties of the SLs were studied over a wide range of temperatures and frequencies. The structure exhibited ferromagnetic behavior at 300 K and ferroelectric behavior over a range of temperatures between 100 and 300 K. A frequency-dependent change in dielectric constant and tangent loss were observed above the ferromagnetic-paramagnetic temperature. The frequency-dependent dielectric anomalies are attributed to the change in metallic and magnetic nature of LSMO and also the interfacial effect of two different phases that are connected alternatively in series. The effect of ferromagnetic LSMO layers on ferroelectric properties of the SLs indicated strong influence of the interfaces. The asymmetric behavior of ferroelectric loop and the capacitance-voltage relationship suggest development of a built field in the SLs due to high strain across the interfaces.

  5. Study of physical properties of integrated ferroelectric/ferromagnetic heterostructures

    NASA Astrophysics Data System (ADS)

    Martínez, R.; Kumar, A.; Palai, R.; Katiyar, R. S.; Scott, J. F.

    2010-06-01

    Superlattices (SLs) with different periodicity of ferromagnetic La0.7Sr0.3MnO3 (LSMO) and ferroelectric Ba0.7Sr0.3TiO3 as constitutive layers were fabricated on conducting LaNiO3 coated (001) oriented MgO substrates using pulsed laser deposition. The crystallinity, ferroelectric, and magnetic properties of the SLs were studied over a wide range of temperatures and frequencies. The structure exhibited ferromagnetic behavior at 300 K and ferroelectric behavior over a range of temperatures between 100 and 300 K. A frequency-dependent change in dielectric constant and tangent loss were observed above the ferromagnetic-paramagnetic temperature. The frequency-dependent dielectric anomalies are attributed to the change in metallic and magnetic nature of LSMO and also the interfacial effect of two different phases that are connected alternatively in series. The effect of ferromagnetic LSMO layers on ferroelectric properties of the SLs indicated strong influence of the interfaces. The asymmetric behavior of ferroelectric loop and the capacitance-voltage relationship suggest development of a built field in the SLs due to high strain across the interfaces.

  6. A New Circuit Simulation Model of Ferroelectric Capacitors

    NASA Astrophysics Data System (ADS)

    Tamura, Tetsuro; Arimoto, Yoshihiro; Ishiwara, Hiroshi

    2002-04-01

    A circuit simulation model of ferroelectric capacitors was developed. Because of the complicated voltage and time dependence of polarization switching, simulation of the hysteretic behavior was applicable in the limited condition where the voltage change was of a constant rate or step like. The new model consists of parallel element capacitors each of which has different coercive voltage, switching charge and switching response to the voltage change. The model can be implemented in a SPICE simulator with simple expression, and it successfully reproduces the voltage and time dependence of polarization change under arbitrary conditions. Circuit simulation using this model can easily predict the behavior of ferroelectric capacitors and problems in the device operation.

  7. Emission from ferroelectric cathodes

    Microsoft Academic Search

    S. E. Sampayan; G. J. Caporaso; C. L. Holmes; E. J. Lauer; D. Prosnitz; D. O. Trimble; G. A. Westenskow

    1994-01-01

    We have recently initiated an investigation of electron emission from ferroelectric cathodes. Our experimental apparatus consisted of an electron diode and a 250 kV, 12 Omega, 70 ns pulsed high voltage power source. A planar triode modulator driven by a synthesized waveform generator initiates the polarization inversion and allows inversion pulse tailoring. The pulsed high voltage power source is capable

  8. Multiferroic Behavior of Gd Based Manganite

    Microsoft Academic Search

    S. Sagar; P. A. Joy; M. R. Anantharaman

    2009-01-01

    Here we report the multiferroic nature of charge ordered manganite\\u000a Gd0.5Sr0.5MnO3 for the first time. The temperature variation of\\u000a dielectric constant shows broad relaxor type ferroelectric transition at\\u000a around 210K and magnetization measurements shows weak ferromagnetism at\\u000a 50K. The dielectric peak is very close to charge ordering temperature\\u000a which is an evidence of the link between electronic state and increase

  9. Structures, electrical properties, and leakage current behaviors of un-doped and Mn-doped lead-free ferroelectric K0.5Na0.5NbO3 films

    NASA Astrophysics Data System (ADS)

    Wang, Lingyan; Ren, Wei; Shi, Peng; Wu, Xiaoqing

    2014-01-01

    Lead-free ferroelectric un-doped and doped K0.5Na0.5NbO3 (KNN) films with different amounts of manganese (Mn) were prepared by a chemical solution deposition method. The thicknesses of all films are about 1.6 ?m. Their phase, microstructure, leakage current behavior, and electrical properties were investigated. With increasing the amounts of Mn, the crystallinity became worse. Fortunately, the electrical properties were improved due to the decreased leakage current density after Mn-doping. The study on leakage behaviors shows that the dominant conduction mechanism at low electric field in the un-doped KNN film is ohmic mode and that at high electric field is space-charge-limited and Pool-Frenkel emission. After Mn doping, the dominant conduction mechanism at high electric field of KNN films changed single space-charge-limited. However, the introduction of higher amount of Mn into the KNN film would lead to a changed conduction mechanism from space-charge-limited to ohmic mode. Consequently, there exists an optimal amount of Mn doping of 2.0 mol. %. The 2.0 mol. % Mn doped KNN film shows the lowest leakage current density and the best electrical properties. With the secondary ion mass spectroscopies and x-ray photoelectron spectroscopy analyses, the homogeneous distribution in the KNN films and entrance of Mn element in the lattice of KNN perovskite structure were also confirmed.

  10. Domain switching of fatigued ferroelectric thin films

    SciTech Connect

    Tak Lim, Yun [Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang 790-784 (Korea, Republic of); Yeog Son, Jong, E-mail: jyson@khu.ac.kr, E-mail: hoponpop@ulsan.ac.kr [Department of Applied Physics, College of Applied Science, Kyung Hee University, Suwon 446-701 (Korea, Republic of); Shin, Young-Han, E-mail: jyson@khu.ac.kr, E-mail: hoponpop@ulsan.ac.kr [Department of Physics and EHSRC, University of Ulsan, Ulsan 680-749 (Korea, Republic of)

    2014-05-12

    We investigate the domain wall speed of a ferroelectric PbZr{sub 0.48}Ti{sub 0.52}O{sub 3} (PZT) thin film using an atomic force microscope incorporated with a mercury-probe system to control the degree of electrical fatigue. The depolarization field in the PZT thin film decreases with increasing the degree of electrical fatigue. We find that the wide-range activation field previously reported in ferroelectric domains result from the change of the depolarization field caused by the electrical fatigue. Domain wall speed exhibits universal behavior to the effective electric field (defined by an applied electric field minus the depolarization field), regardless of the degree of the electrical fatigue.

  11. improved room-temperature dielectric constant. The dielectric properties of the composites under different applied-field strength were

    E-print Network

    Segall, Paul

    . & Herbert, J. Electroceramics (Chapman & Hall, London, 1995). 15. Cross, L. E. Ferroelectric ceramics) Electroactive Polymers (MRS Symp. Proc. Vol. 600, MRS, Warrendale PA, 1999). 3. Nalwa, H. (ed.) Ferroelectric and relaxor ferroelectric behavior in electron-irradiated poly(vinylidene fluoride

  12. Molecular ferroelectrics: where electronics meet biology

    PubMed Central

    Li, Jiangyu; Liu, Yuanming; Zhang, Yanhang; Cai, Hong-Ling; Xiong, Ren-Gen

    2013-01-01

    In the last several years, we have witnessed significant advances in molecular ferroelectrics, with ferroelectric properties of molecular crystals approaching those of barium titanate. In addition, ferroelectricity has been observed in biological systems, filling an important missing link in bioelectric phenomena. In this perspective, we will present short historical notes on ferroelectrics, followed by overview on the fundamentals of ferroelectricity. Latest development in molecular ferroelectrics and biological ferroelectricity will then be highlighted, and their implications and potential applications will be discussed. We close by noting molecular ferroelectric as an exciting frontier between electronics and biology, and a number of challenges ahead are also noted. PMID:24018952

  13. Semiconductor/relaxor 0–3 type composites without thermal depolarization in Bi0.5Na0.5TiO3-based lead-free piezoceramics

    NASA Astrophysics Data System (ADS)

    Zhang, Ji; Pan, Zhao; Guo, Fei-Fei; Liu, Wen-Chao; Ning, Huanpo; Chen, Y. B.; Lu, Ming-Hui; Yang, Bin; Chen, Jun; Zhang, Shan-Tao; Xing, Xianran; Rödel, Jürgen; Cao, Wenwu; Chen, Yan-Feng

    2015-03-01

    Commercial lead-based piezoelectric materials raised worldwide environmental concerns in the past decade. Bi0.5Na0.5TiO3-based solid solution is among the most promising lead-free piezoelectric candidates; however, depolarization of these solid solutions is a longstanding obstacle for their practical applications. Here we use a strategy to defer the thermal depolarization, even render depolarization-free Bi0.5Na0.5TiO3-based 0–3-type composites. This is achieved by introducing semiconducting ZnO particles into the relaxor ferroelectric 0.94Bi0.5Na0.5TiO3–0.06BaTiO3 matrix. The depolarization temperature increases with increasing ZnO concentration until depolarization disappears at 30 mol% ZnO. The semiconducting nature of ZnO provides charges to partially compensate the ferroelectric depolarization field. These results not only pave the way for applications of Bi0.5Na0.5TiO3-based piezoceramics, but also have great impact on the understanding of the mechanism of depolarization so as to provide a new design to optimize the performance of lead-free piezoelectrics.

  14. Ferroelectric, pyroelectric and dielectric properties of complex perovskite-structured Pb 0.84Ba 0.16(Zr 0.44Ti 0.40Fe 0.08Nb 0.08)O 3 ceramics

    Microsoft Academic Search

    Sukum Eitssayeam; Uraiwan Intatha; Kamonpan Pengpat; Gobwute Rujijanagul; Kenneth J. D. MacKenzie; Tawee Tunkasiri

    2008-01-01

    Relaxor ferroelectrics with A?A??(B?B??)O3 – type perovskite structures have attracted much attention because of their excellent dielectric and electromechanical properties. The physical properties or device parameters of PZT can be tailored by improved synthesis and processing techniques and by making suitable substitutions into the A and\\/or B sites. In this study, Pb0.84Ba0.16(Zr0.44Ti0.40Fe0.08Nb0.08)O3 ceramics were prepared by solid state reaction and

  15. Kinetics of nucleation of the ferroelectric transitions in PbMg1/3Nb2/3O3 and PbMg1/3Nb2/3O3-12%PbTiO3

    NASA Astrophysics Data System (ADS)

    Colla, Eugene V.; Jeliazkov, Jeliazko R.; Weissman, M. B.; Viehland, D. D.; Ye, Zuo-Gang

    2014-07-01

    The nucleation kinetics of the formation of ordered ferroelectric phases from the glassy relaxor states of PbMg1/3Nb2/3O3 (PMN) and of solid solutions of PMN and PbTiO3 is investigated. A delay time, dependent on field and temperature, is found to precede a rather rapid establishment of macroscopic polarization. The qualitative form of the temperature dependence follows prior theory for the lag preceding homogeneous nucleation of a crystal from a glass. However, the increase of the lag time as the "melting" line is approached from below is stronger than expected.

  16. Stability of ferroelectric ice

    E-print Network

    Iitaka, Toshiaki

    2010-01-01

    We theoretically study the stability conditions of the ferroelectric ice of the Cmc21 structure, which has been considered, for decades, one of the most promising candidates of the low temperature proton-ordered phase of pure ice Ih. It turned out that the Cmc21 structure is stable only with a certain amount of dopant and the true proton-ordered phase of pure ice Ih remains to be found at lower temperature. Implication for spin ice is mentioned.

  17. Effect of excess Bi2O3 on the ferroelectric properties of SrBi2Ta2O9 Jung-Kun Lee, Byungwoo Park, Kug-Sun Honga)

    E-print Network

    Park, Byungwoo

    Effect of excess Bi2O3 on the ferroelectric properties of SrBi2Ta2O9 ceramics Jung-Kun Lee of strontium­bismuth­tantalate SBT ceramics was explored with the aid of r(T), ferroelectric hysteresis loop, x, the effect of bismuth content on phase-transition behavior, ferroelectric property, and crystal structure

  18. A physically-derived nonquasi-static model of ferroelectric amplifiers for computer-aided device simulation - Part I: The ferroelectric common-drain amplifier

    NASA Astrophysics Data System (ADS)

    Sayyah, Rana; Hunt, Mitchell; Ho, Fat D.

    2013-08-01

    A physically-derived nonquasi-static model describing the behavior of the ferroelectric common-drain amplifier is presented. The model is based on the method of partitioned channel and ferroelectric layers and is valid in accumulation, depletion, and the three inversion cases: weak, moderate, and strong. The equations of this model are based on the standard MOSFET equations that have been modified to reflect the ferroelectric properties. The model code is written in MATLAB and outputs voltage plots with respect to time. The accuracy and effectiveness of the model are verified by a few test cases, where the modeled results are compared to empirically-derived oscilloscope plots.

  19. Analysis and design of ferroelectric-based smart antenna structures

    NASA Astrophysics Data System (ADS)

    Ramesh, Prashanth; Washington, Gregory N.

    2009-03-01

    Ferroelectrics in microwave antenna systems offer benefits of electronic tunability, compact size and light weight, speed of operation, high power-handling, low dc power consumption, and potential for low loss and cost. Ferroelectrics allow for the tuning of microwave devices by virtue of the nonlinear dependence of their dielectric permittivity on an applied electric field. Experiments on the field-polarization dependence of ferroelectric thin films show variation in dielectric permittivity of up to 50%. This is in contrast to the conventional dielectric materials used in electrical devices which have a relatively constant permittivity, indicative of the linear field-polarization curve. Ferroelectrics, with their variable dielectric constant introduce greater flexibility in correction and control of beam shapes and beam direction of antenna structures. The motivation behind this research is applying ferroelectrics to mechanical load bearing antenna structures, but in order to develop such structures, we need to understand not just the field-permittivity dependence, but also the coupled electro-thermo-mechanical behavior of ferroelectrics. In this paper, two models are discussed: a nonlinear phenomenological model relating the applied fields, strains and temperature to the dielectric permittivity based on the Devonshire thermodynamic framework, and a phenomenological model relating applied fields and temperature to the dielectric loss tangent. The models attempt to integrate the observed field-permittivity, strain-permittivity and temperature-permittivity behavior into one single unified model and extend the resulting model to better fit experimental data. Promising matches with experimental data are obtained. These relations, coupled with the expression for operating frequency vs. the permittivity are then used to understand the bias field vs. frequency behavior of the antenna. Finally, the effect of the macroscopic variables on the antenna radiation efficiency is discussed.

  20. Polarization coupling in ferroelectric multilayers

    Microsoft Academic Search

    M. B. Okatan; J. V. Mantese; S. P. Alpay

    2009-01-01

    A thermodynamic model was developed to understand the role of charge compensation at the interlayer interfaces in compositionally graded monodomain ferroelectric multilayers. The polarization mismatch between the ferroelectric layers generates depoling fields with the polarization in each layer varying from its bulk uncoupled value as to adapt to the electrical boundary conditions. By treating the strength of the electrostatic field

  1. Polarization coupling in ferroelectric multilayers

    Microsoft Academic Search

    M. B. Okatan; J. V. Mantese; S. P. Alpay

    2009-01-01

    A thermodynamic model was developed to understand the role of charge compensation at the interlayer interfaces in compositionally graded monodomain ferroelectric multilayers. The polarization mismatch be- tween the ferroelectric layers generates depoling fields with the polarization in each layer varying from its bulk uncoupled value as to adapt to the electrical boundary conditions. By treating the strength of the electrostatic

  2. Ferroelectricity in ultrathin perovskite films

    Microsoft Academic Search

    Dillon D. Fong; G. Brian Stephenson; Stephen K. Streiffer; Jeffrey A. Eastman; Orlando Auciello; Paul H. Fuoss; Carol Thompson

    2004-01-01

    Understanding the suppression of ferroelectricity in perovskite thin films is a fundamental issue that has remained unresolved for decades. We report a synchrotron x-ray study of lead titanate as a function of temperature and film thickness for films as thin as a single unit cell. At room temperature, the ferroelectric phase is stable for thicknesses down to 3 unit cells

  3. Examining graphene field effect sensors for ferroelectric thin film studies.

    PubMed

    Rajapitamahuni, A; Hoffman, J; Ahn, C H; Hong, X

    2013-09-11

    We examine a prototype graphene field effect sensor for the study of the dielectric constant, pyroelectric coefficient, and ferroelectric polarization of 100-300 nm epitaxial (Ba,Sr)TiO3 thin films. Ferroelectric switching induces hysteresis in the resistivity and carrier density of n-layer graphene (n = 1-5) below 100 K, which competes with an antihysteresis behavior activated by the combined effects of electric field and temperature. We also discuss how the polarization asymmetry and interface charge dynamics affect the electronic properties of graphene. PMID:23924380

  4. Characterization of a Common-Source Amplifier Using Ferroelectric Transistors

    NASA Technical Reports Server (NTRS)

    Hunt, Mitchell; Sayyah, Rana; MacLeond, Todd C.; Ho, Pat D.

    2010-01-01

    This paper presents empirical data that was collected through experiments using a FeFET in the established common-source amplifier circuit. The unique behavior of the FeFET lends itself to interesting and useful operation in this widely used common-source amplifier. The paper examines the effect of using a ferroelectric transistor for the amplifier. It also examines the effects of varying load resistance, biasing, and input voltages on the output signal and gives several examples of the output of the amplifier for a given input. The difference between a commonsource amplifier using a ferroelectric transistor and that using a MOSFET is addressed.

  5. Conduction at a ferroelectric interface

    DOE PAGESBeta

    Marshall, Matthew S. J.; Malashevich, Andrei; Disa, Ankit S.; Han, Myung-Guen; Chen, Hanghui; Zhu, Yimei; Ismail-Beigi, Sohrab; Walker, Frederick J.; Ahn, Charles H.

    2014-11-01

    Typical logic elements utilizing the field effect rely on the change in carrier concentration due to the field in the channel region of the device. Ferroelectric-field-effect devices provide a nonvolatile version of this effect due to the stable polarization order parameter in the ferroelectric. In this work, we describe an oxide/ oxide ferroelectric heterostructure device based on (001)-oriented PbZr??.?Ti?.?O?-LaNiO? where the dominant change in conductivity is a result of a significant mobility change in the interfacial channel region. The effect is confined to a few atomic layers at the interface and is reversible by switching the ferroelectric polarization. More interestingly,more »in one polarization state, the field effect induces a 1.7-eV shift of the interfacial bands to create a new conducting channel in the interfacial PbO layer of the ferroelectric.« less

  6. Conduction at a Ferroelectric Interface

    NASA Astrophysics Data System (ADS)

    Marshall, Matthew S. J.; Malashevich, Andrei; Disa, Ankit S.; Han, Myung-Geun; Chen, Hanghui; Zhu, Yimei; Ismail-Beigi, Sohrab; Walker, Frederick J.; Ahn, Charles H.

    2014-11-01

    Typical logic elements utilizing the field effect rely on the change in carrier concentration due to the field in the channel region of the device. Ferroelectric-field-effect devices provide a nonvolatile version of this effect due to the stable polarization order parameter in the ferroelectric. In this work, we describe an oxide/oxide ferroelectric heterostructure device based on (001)-oriented PbZr0.2Ti0.8O3-LaNiO3 where the dominant change in conductivity is a result of a significant mobility change in the interfacial channel region. The effect is confined to a few atomic layers at the interface and is reversible by switching the ferroelectric polarization. More interestingly, in one polarization state, the field effect induces a 1.7-eV shift of the interfacial bands to create a new conducting channel in the interfacial PbO layer of the ferroelectric.

  7. Conduction at a ferroelectric interface

    DOE PAGESBeta

    Marshall, Matthew S. J. [Yale Univ., New Haven, CT (United States); Malashevich, Andrei [Yale Univ., New Haven, CT (United States); Disa, Ankit S. [Yale Univ., New Haven, CT (United States); Han, Myung-Guen [Brookhaven National Lab. (BNL), Upton, NY (United States); Chen, Hanghui [Yale Univ., New Haven, CT (United States); Zhu, Yimei [Brookhaven National Lab. (BNL), Upton, NY (United States); Ismail-Beigi, Sohrab [Yale Univ., New Haven, CT (United States); Walker, Frederick J. [Yale Univ., New Haven, CT (United States); Ahn, Charles H. [Yale Univ., New Haven, CT (United States);

    2014-11-01

    Typical logic elements utilizing the field effect rely on the change in carrier concentration due to the field in the channel region of the device. Ferroelectric-field-effect devices provide a nonvolatile version of this effect due to the stable polarization order parameter in the ferroelectric. In this work, we describe an oxide/ oxide ferroelectric heterostructure device based on (001)-oriented PbZr??.?Ti?.?O?-LaNiO? where the dominant change in conductivity is a result of a significant mobility change in the interfacial channel region. The effect is confined to a few atomic layers at the interface and is reversible by switching the ferroelectric polarization. More interestingly, in one polarization state, the field effect induces a 1.7-eV shift of the interfacial bands to create a new conducting channel in the interfacial PbO layer of the ferroelectric.

  8. Monte Carlo simulation of ferroelectric domain structure and applied field response in two dimensions

    SciTech Connect

    Potter, B. G. Jr. [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)] [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States); Tikare, V. [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)] [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States); Tuttle, B. A. [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)] [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)

    2000-05-01

    A two-dimensional, lattice-Monte Carlo approach, based upon the energy minimization of an ensemble of electric dipoles, was developed to simulate ferroelectric domain behavior. The model utilizes a Hamiltonian for the total energy based upon electrostatic terms involving dipole-dipole interactions, local polarization gradients, and the influence of applied electric fields. The impact of boundary conditions on the domain configurations obtained was also examined. In general, the model exhibits domain structure characteristics consistent with those observed in a tetragonally distorted ferroelectric. The model was also extended to enable the simulation of ferroelectric hysteresis behavior. Simulated hysteresis loops were found to be very similar in appearance to those observed experimentally in actual materials. This qualitative agreement between the simulated hysteresis loop characteristics and real ferroelectric behavior was also confirmed in simulations run over a range of simulation temperatures and applied field frequencies. (c) 2000 American Institute of Physics.

  9. From spin induced ferroelectricity to dipolar glasses: Spinel chromites and mixed delafossites

    NASA Astrophysics Data System (ADS)

    Maignan, A.; Martin, C.; Singh, K.; Simon, Ch.; Lebedev, O. I.; Turner, S.

    2012-11-01

    Magnetoelectric multiferroics showing coupling between polarization and magnetic order are attracting much attention. For instance, they could be used in memory devices. Metal-transition oxides are provided several examples of inorganic magnetoelectric multiferroics. In the present short review, spinel and delafossite chromites are described. For the former, an electric polarization is evidenced in the ferrimagnetic state for ACr2O4 polycrystalline samples (A=Ni, Fe, Co). The presence of a Jahn-Teller cation such as Ni2+ at the A site is shown to yield larger polarization values. In the delafossites, substitution by V3+ at the Cr or Fe site in CuCrO2 (CuFeO2) suppresses the complex antiferromagnetic structure at the benefit of a spin glass state. The presence of cation disorder, probed by transmission electron microscopy, favors relaxor-like ferroelectricity. The results on the ferroelectricity of ferrimagnets and insulating spin glasses demonstrate that, in this research field, transition-metal oxides are worth to be studied.

  10. Ferroelectric domain structure of anisotropically strained NaNbO3 epitaxial thin films

    NASA Astrophysics Data System (ADS)

    Schwarzkopf, J.; Braun, D.; Schmidbauer, M.; Duk, A.; Wördenweber, R.

    2014-05-01

    NaNbO3 thin films have been grown under anisotropic biaxial strain on several oxide substrates by liquid-delivery spin metalorganic chemical vapor deposition. Compressive lattice strain of different magnitude, induced by the deposition of NaNbO3 films with varying film thickness on NdGaO3 single crystalline substrates, leads to modifications of film orientation and phase symmetry, which are similar to the phase transitions in Pb-containing oxides near the morphotropic phase boundary. Piezoresponse force microscopy measurements exhibit large out-of-plane polarization components, but no distinctive domain structure, while C-V measurements indicate relaxor properties in these films. When tensile strain is provoked by the epitaxial growth on DyScO3, TbScO3, and GdScO3 single crystalline substrates, NaNbO3 films behave rather like a normal ferroelectric. The application of these rare-earth scandate substrates yields well-ordered ferroelectric stripe domains of the type a1/a2 with coherent domain walls aligned along the [001] substrate direction as long as the films are fully strained. With increasing plastic lattice relaxation, initially, a 2D domain pattern with still exclusively in-plane electric polarization, and finally, domains with in-plane and out-of-plane polar components evolve.

  11. Diffuse phase transition and dielectric tunability of Ba(Zr y Ti 1? y )O 3 relaxor ferroelectric ceramics

    Microsoft Academic Search

    X. G. Tang; K.-H. Chew; H. L. W. Chan

    2004-01-01

    Barium zirconate titanate Ba(ZryTi1?y)O3 (BZT, y=0.2, 0.25, 0.30, 0.35) ceramics have been prepared by a sol–gel process. The temperature dependence of dielectric permittivity of the ceramics has been investigated. The results show that the phase transition temperature TC (or Tm) is suppressed with increasing Zr content. The degree of diffuseness of the phase transition is more pronounced for higher Zr

  12. Pyroelectric waste heat energy harvesting using relaxor ferroelectric 8/65/35 PLZT and the Olsen cycle

    E-print Network

    Pilon, Laurent

    in the online journal) 1. Introduction Waste heat is rejected as a by-product of power, refrigeration or heat.seas.ucla.edu/pilon. For example, thermoelectric devices directly convert a steady-state temperature difference at the junction

  13. Energy harvesting by nonlinear capacitance variation for a relaxor ferroelectric poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) terpolymer

    NASA Astrophysics Data System (ADS)

    Zhu, H.; Pruvost, S.; Cottinet, P. J.; Guyomar, D.

    2011-05-01

    The present letter describes the investigation of the electrostatic energy harvesting through nonlinear capacitance variation caused by changes in temperature for a poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) [P(VDF-TrFE-CFE)] terpolymer. Owing to the electric tunability of the terpolymer, the harvested energy can-using an Ericsson cycle-be simulated from permittivity under a dc electric field. When going from 25 to 0 °C, it was found, from simulation, that the harvested energy increased up to 240 mJ/cm3 when raising the electric field at 80 kV/mm. Experimental measurement was also carried out, thus confirming the feasibility of electrostatic energy harvesting through low temperature Ericsson cycle.

  14. Faceting oscillations in nano-ferroelectrics

    SciTech Connect

    Scott, J. F., E-mail: jfs32@cam.ac.uk, E-mail: ashok553@nplindia.org [Cavendish Laboratory, Cambridge University, Cambridge (United Kingdom); Kumar, Ashok, E-mail: jfs32@cam.ac.uk, E-mail: ashok553@nplindia.org [CSIR-National Physical Laboratory, Delhi (India)

    2014-08-04

    We observe periodic faceting of 8-nm diameter ferroelectric disks on a 10?s time-scale when thin Pb(Zr{sub 0.52}Ti{sub 0.48})O{sub 3} film is exposed to constant high-resolution transmission electron microscopy beams. The oscillation is between circular disk geometry and sharply faceted hexagons. The behavior is analogous to that of spin structure and magnetic domain wall velocity oscillations in permalloy [Bisig et al., Nat. Commun. 4, 2328 (2013)], involving overshoot and de-pinning from defects [Amann et al., J. Rheol. 57, 149–175 (2013)].

  15. Micro- and nanodomain imaging in uniaxial ferroelectrics: Joint application of optical, confocal Raman, and piezoelectric force microscopy

    SciTech Connect

    Shur, V. Ya., E-mail: vladimir.shur@urfu.ru; Zelenovskiy, P. S. [Ferroelectric Laboratory, Institute of Natural Sciences, Ural Federal University, 620000 Ekaterinburg (Russian Federation)

    2014-08-14

    The application of the most effective methods of the domain visualization in model uniaxial ferroelectrics of lithium niobate (LN) and lithium tantalate (LT) family, and relaxor strontium-barium niobate (SBN) have been reviewed in this paper. We have demonstrated the synergetic effect of joint usage of optical, confocal Raman, and piezoelectric force microscopies which provide extracting of the unique information about formation of the micro- and nanodomain structures. The methods have been applied for investigation of various types of domain structures with increasing complexity: (1) periodical domain structure in LN and LT, (2) nanodomain structures in LN, LT, and SBN, (3) nanodomain structures in LN with modified surface layer, (4) dendrite domain structure in LN. The self-assembled appearance of quasi-regular nanodomain structures in highly non-equilibrium switching conditions has been considered.

  16. Pressure-induced polar phases in relaxor multiferroic PbFe0.5Nb0.5O3

    NASA Astrophysics Data System (ADS)

    Kozlenko, D. P.; Kichanov, S. E.; Lukin, E. V.; Dang, N. T.; Dubrovinsky, L. S.; Liermann, H.-P.; Morgenroth, W.; Kamynin, A. A.; Gridnev, S. A.; Savenko, B. N.

    2014-05-01

    The structural, magnetic, and vibrational properties of PbFe0.5Nb0.5O3 relaxor multiferroic have been studied by means of x-ray, neutron powder diffraction, and Raman spectroscopy at pressures up to 30 GPa. Two successive structural phase transitions from the initial R3m polar phase to Cm and Pm monoclinic polar phases were observed at P = 5.5 and 8.5 GPa. Both transitions are associated with anomalies in pressure behavior of several stretching and bending modes of oxygen octahedra as well as Fe/Nb localized vibrational modes. The G-type antiferromagnetic order remains stable upon compression up to 6.4 GPa, assuming possible multiferroic properties of pressure-induced phases. The Néel temperature increases with a pressure coefficient (1/TN)dTN/dP=0.012 GPa-1. The observed pressure-induced phenomena in PbFe0.5Nb0.5O3 are in drastic contrast with conventional multiferroics, exhibiting a general tendency towards a suppression of polar phases and/or magnetoelectric coupling under pressure.

  17. Conductivity and interfacial charge induced phenomena in ferroelectric films and composites

    NASA Astrophysics Data System (ADS)

    Wong, Chung Kwan

    2005-11-01

    Ferroelectric materials are polar dielectrics which normally possess small but finite electrical conductivity. We believe that conductivity in ferroelectrics can induce new phenomena or modify known physical phenomena, which may be difficult to understand if the materials are regarded as perfectly insulating. In this thesis, some "anomalous" phenomena are investigated for which the origins are still under debate in literature, and we suggest that these may very well be manifestations of electrical conduction and electric charges. Ferroelectric systems of interest to this investigation include composites and films. Electrical conductivity in ferroelectric composites allows free charge to accumulate at the matrix-inclusion interfaces. We focus on the role of interfacial charge at such interfaces in ferroelectric 0--3 composites (normally, ferroelectric ceramic inclusions dispersed in polymer matrices) in the interpretation of their peculiar experimental results. The effect of interfacial charge on the piezoelectric properties of ferroelectric 0--3 composites and the effect of electrical conductivity on their dielectric and piezoelectric properties are also investigated. Our previously developed model has been extended to include the additional contribution from the deformation of the inclusion particles (for discussing the effect of interfacial charge) due to the applied stresses in piezoelectric measurements, and for discussing the effect of conductivity to include its contribution as well as the frequency of measurement. Phenomena induced by electrical conductivity in other ferroelectric systems have also been studied. We consider the effects of electrical conductivity on the dynamic polarization behavior of ferroelectric films. Using a parallelogram-like P-E hysteresis model for the film material, explicit expressions are obtained for describing the D-E loops of ferroelectric films as would be measured from a Sawyer-Tower circuit which originally assumes the measured sample is insulating. The calculation shows that resistive losses inflate the ferroelectric loop to a varying extent. Theoretical simulations have also been performed to study the anomalously large polarization shift behavior in compositionally graded ferroelectric films and the bias field dependent dielectricity of ferroelectric thin films. The model is capable of modeling saturated and unsaturated hysteresis behavior under arbitrary fields. (Abstract shortened by UMI.)

  18. Relaxor-PbTiO3 Single Crystals for Various Applications

    PubMed Central

    Zhang, Shujun; Li, Fei; Luo, Jun; Sahul, Raffi; Shrout, Thomas R.

    2014-01-01

    Piezoelectric materials lie at the heart of electromechanical devices. Applications include actuators, ultrasonic imaging, high intensity focused ultrasound, underwater ultrasound, nondestructive evaluation transducer, pressure sensors, and accelerometers, to name a few. In this work, the advantages and disadvantages of relaxor-PbTiO3-based single crystals are discussed, based on the requirements (figure of merit) of various applications, with emphasis on recent developments of the shear properties of single crystals as a function of temperature and applied fields. PMID:25004527

  19. Ferroelectric optical image comparator

    DOEpatents

    Butler, Michael A. (Albuquerque, NM); Land, Cecil E. (Albuquerque, NM); Martin, Stephen J. (Albuquerque, NM); Pfeifer, Kent B. (Los Lunas, NM)

    1993-01-01

    A ferroelectric optical image comparator has a lead lanthanum zirconate titanate thin-film device which is constructed with a semi-transparent or transparent conductive first electrode on one side of the thin film, a conductive metal second electrode on the other side of the thin film, and the second electrode is in contact with a nonconducting substrate. A photoinduced current in the device represents the dot product between a stored image and an image projected onto the first electrode. One-dimensional autocorrelations are performed by measuring this current while displacing the projected image.

  20. Ferroelectric Thin Films for Electronic Applications

    NASA Astrophysics Data System (ADS)

    Udayakumar, K. R.

    This study yokes together the feasibility of a family of PbO-based perovskite-structured ferroelectric thin films as functional elements in nonvolatile random access memories (NVRAMs), in high capacity dynamic RAMs, and in a new class of flexure wave piezoelectric ultrasonic micromotors. The dielectric and ferroelectric properties of lead zirconate titanate (PZT) thin films were dependent on thickness; at saturation, the films were characterized by a relative permittivity of 1300, remanent polarization of 36 muC/cm^2 and breakdown strength of over 1 MV/cm. The temperature dependence of permittivity revealed an anomalous behavior with the film annealing temperature. Based on the ferroelectric properties in the bulk, thin films in the lead zirconate -lead zinc niobate (PZ-PZN) solid solution system at 8-12% PZN, examined as alternate compositions for ferroelectric memories, feature switched charges of 4-14 mu C/cm^2, with coercive and saturation voltages less than the semiconductor operating voltage of 5 V. Rapid thermally annealed lead magnesium niobate titanate films were privy to weak signal dielectric permittivity of 2900, remanent polarization of 11 muC/cm^2, and a storage density of 210 fC/mum^2 at 5 V; the films merit consideration for potential applications in ultra large scale integrated circuits as also ferroelectric nonvolatile RAMs. The high breakdown strength and relative permittivity of the PZT films entail maximum stored energy density 10^3 times larger than a silicon electrostatic motor. The longitudinal piezoelectric strain coefficient d_{33 } was measured to be 220 pC/N at a dc bias of 75 kV/cm. The transverse piezoelectric strain coefficient d_{31} bore a nonlinear relationship with the electric field; at 200 kV/cm, d _{31} was -88 pC/N. The development of the piezoelectric ultrasonic micromotors from the PZT thin films, and the architecture of the stator structures are described. Nonoptimized prototype micromotors show rotational velocities of 100-300 rpm at drives of 3-5 V.

  1. Spectroscopic signature for ferroelectric ice

    NASA Astrophysics Data System (ADS)

    Wójcik, Marek J.; G?ug, Maciej; Boczar, Marek; Boda, ?ukasz

    2014-09-01

    Various forms of ice exist within our galaxy. Particularly intriguing type of ice - ‘ferroelectric ice' was discovered experimentally and is stable in temperatures below 72 K. This form of ice can generate enormous electric fields and can play an important role in planetary formation. In this letter we present Car-Parrinello simulation of infrared spectra of ferroelectric ice and compare them with spectra of hexagonal ice. Librational region of the spectra can be treated as spectroscopic signature of ice XI and can be of help to identify ferroelectric ice in the Universe.

  2. Monte Carlo simulation of ferroelectric domain structure: Electrostatic and elastic strain energy contributions

    SciTech Connect

    POTTER JR.,BARRETT G.; TUTTLE,BRUCE A.; TIKARE,VEENA

    2000-04-04

    A lattice-Monte Carlo approach was developed to simulate ferroelectric domain behavior. The model utilizes a Hamiltonian for the total energy that includes electrostatic terms (involving dipole-dipole interactions, local polarization gradients, and applied electric field), and elastic strain energy. The contributions of these energy components to the domain structure and to the overall applied field response of the system were examined. In general, the model exhibited domain structure characteristics consistent with those observed in a tetragonally distorted ferroelectric. Good qualitative agreement between the appearance of simulated electrical hysteresis loops and those characteristic of real ferroelectric materials was found.

  3. Ferroelectric ordering in imidazolium perchlorate

    NASA Astrophysics Data System (ADS)

    Paj?k, Z.; Czarnecki, P.; Szafra?ska, B.; Ma?uszy?ska, H.; Fojud, Z.

    2006-04-01

    Imidazolium perchlorate has been synthesized and studied over a wide range of temperatures by differential scanning calorimetry, x-ray diffraction, proton magnetic resonance, optical observation, and dielectric spectroscopy. Polymorphic solid-solid phase transitions have been disclosed at 487, 373, and 247K. The crystal structure at 298K has been determined as trigonal, space group R3m, Z =1 with a =5.484(1)Å and ? =95.18(2)°. The imidazolium cations are strongly disordered, while the perchlorate ions are well ordered. At 385K the crystal structure remains trigonal, space group R3¯m, a =5.554(1)Å and ? =95.30(2)°. Both ionic sublattices are orientationally disordered. Temperature evolution of the molecular dynamics of the imidazolium cation has been characterized. In spite of a high cationic disorder, dielectric measurements have revealed the polar properties of the crystal. It appears to be a new ferroelectric compound with the Curie point at 373K. The spontaneous polarization originates predominantly from the behavior of slightly distorted perchlorate anion.

  4. Monte Carlo Simulation of Ferroelectric Domain Structure and Applied Field Response in Two Dimensions

    SciTech Connect

    Potter, Jr., B.G.; Tikare, V.; Tuttle, B.A.

    1999-06-30

    A 2-D, lattice-Monte Carlo approach was developed to simulate ferroelectric domain structure. The model currently utilizes a Hamiltonian for the total energy based only upon electrostatic terms involving dipole-dipole interactions, local polarization gradients and the influence of applied electric fields. The impact of boundary conditions on the domain configurations obtained was also examined. In general, the model exhibits domain structure characteristics consistent with those observed in a tetragonally distorted ferroelectric. The model was also extended to enable the simulation of ferroelectric hysteresis behavior. Simulated hysteresis loops were found to be very similar in appearance to those observed experimentally in actual materials. This qualitative agreement between the simulated hysteresis loop characteristics and real ferroelectric behavior was also confirmed in simulations run over a range of simulation temperatures and applied field frequencies.

  5. Ferroelectric capacitor with reduced imprint

    DOEpatents

    Evans, Jr., Joseph T. (13609 Verbena Pl., NE., Albuquerque, NM 87112); Warren, William L. (7716 Wm. Moyers Ave., NE., Albuquerque, NM 87122); Tuttle, Bruce A. (12808 Lillian Pl., NE., Albuquerque, NM 87122); Dimos, Duane B. (6105 Innsbrook Ct., NE., Albuquerque, NM 87111); Pike, Gordon E. (1609 Cedar Ridge, NE., Albuquerque, NM 87112)

    1997-01-01

    An improved ferroelectric capacitor exhibiting reduced imprint effects in comparison to prior art capacitors. A capacitor according to the present invention includes top and bottom electrodes and a ferroelectric layer sandwiched between the top and bottom electrodes, the ferroelectric layer comprising a perovskite structure of the chemical composition ABO.sub.3 wherein the B-site comprises first and second elements and a dopant element that has an oxidation state greater than +4. The concentration of the dopant is sufficient to reduce shifts in the coercive voltage of the capacitor with time. In the preferred embodiment of the present invention, the ferroelectric element comprises Pb in the A-site, and the first and second elements are Zr and Ti, respectively. The preferred dopant is chosen from the group consisting of Niobium, Tantalum, and Tungsten. In the preferred embodiment of the present invention, the dopant occupies between 1 and 8% of the B-sites.

  6. Study of nanostructural behavior and transport properties of BaTiO 3 doped vanadate glasses and glass–ceramics dispersed with ferroelectric nanocrystals

    Microsoft Academic Search

    M. S. Al-Assiri; M. M. El-Desoky; A. Al-Hajry; A. Al-Shahrani; A. M. Al-Mogeeth; A. A. Bahgat

    2009-01-01

    Nanostructural behavior and electrical properties of BaTiO3-(100?x)V2O5 glasses (where x=35, 40, 45 and 50mol%) and their corresponding nanocrystalline glass–ceramics were studied. Scanning electron microscopy (SEM) of quenched glasses, confirm the amorphous nature of the glasses present. Also, the overall features of X-ray diffraction (XRD) confirm the amorphous nature of the present glasses. Transmission electron micrograph (TEM) and XRD of the

  7. Ferroelectric infrared detector and method

    DOEpatents

    Lashley, Jason Charles (Sante Fe, NM); Opeil, Cyril P. (Chestnut Hill, MA); Smith, James Lawrence (Los Alamos, NM)

    2010-03-30

    An apparatus and method are provided for sensing infrared radiation. The apparatus includes a sensor element that is positioned in a magnetic field during operation to ensure a .lamda. shaped relationship between specific heat and temperature adjacent the Curie temperature of the ferroelectric material comprising the sensor element. The apparatus is operated by inducing a magnetic field on the ferroelectric material to reduce surface charge on the element during its operation.

  8. Polarization coupling in ferroelectric multilayers

    NASA Astrophysics Data System (ADS)

    Okatan, M. B.; Mantese, J. V.; Alpay, S. P.

    2009-05-01

    A thermodynamic model was developed to understand the role of charge compensation at the interlayer interfaces in compositionally graded monodomain ferroelectric multilayers. The polarization mismatch between the ferroelectric layers generates depoling fields with the polarization in each layer varying from its bulk uncoupled value as to adapt to the electrical boundary conditions. By treating the strength of the electrostatic field as a phenomenological parameter, it is shown that if there are localized charges to compensate for the polarization mismatch and relax the depolarization fields, ferroelectric layers behave independently of each other and exhibit a dielectric response that can be described as the sum of their corresponding intrinsic uncoupled dielectric properties. For perfectly insulating heterostructures with no localized charges, the depolarization field is minimized by lowering the polarization difference between layers, yielding a ferroelectric multilayer that behaves as if it were a single ferroelectric material. There exists an optimum value of coupling strength at which average polarization of the multilayer is maximized. Furthermore, ferroelectric multilayers may display a colossal dielectric response dependant upon the interlayer electrostatic interactions.

  9. Ferroelectric Polarization Reversal by a Magnetic Field in Multiferroic Y-type Hexaferrite Ba2Mg2Fe12O22

    NASA Astrophysics Data System (ADS)

    Taniguchi, Kouji; Abe, Nobuyuki; Ohtani, Shintaro; Umetsu, Hiroshi; Arima, Taka-hisa

    2008-03-01

    Coexistence of the ferroelectric polarization and spontaneous magnetization has been found in Y-type hexaferrite Ba2Mg2Fe12O22. The reversal of magnetization by a small magnetic field below ˜0.02 T accompanies an electric polarization reversal through the clamping of ferrimagnetic and ferroelectric domain walls. This behavior can be potentially used as a magnetically rewritable ferroelectric memory and an electrically rewritable magnetic memory.

  10. Programmable ferroelectric tunnel memristor

    NASA Astrophysics Data System (ADS)

    Quindeau, Andy; Hesse, Dietrich; Alexe, Marin

    2014-02-01

    We report an analogously programmable memristor based on genuine electronic resistive switching combining ferroelectric switching and electron tunneling. The tunnel current through an 8 unit cell thick epitaxial Pb(Zr[0.2]Ti[0.8])O[3] film sandwiched between La[0.7]Sr[0.3]MnO[3] and cobalt electrodes obeys the Kolmogorov-Avrami-Ishibashi model for bidimensional growth with a characteristic switching time in the order of 10^-7 seconds. The analytical description of switching kinetics allows us to develop a characteristic transfer function that has only one parameter viz. the characteristic switching time and fully predicts the resistive states of this type of memristor.

  11. Finite-size effects of hysteretic dynamics in multilayer graphene on a ferroelectric

    NASA Astrophysics Data System (ADS)

    Morozovska, Anna N.; Pusenkova, Anastasiia S.; Varenyk, Oleksandr V.; Kalinin, Sergei V.; Eliseev, Eugene A.; Strikha, Maxym V.

    2015-06-01

    The origin and influence of finite-size effects on the nonlinear dynamics of space charge stored by multilayer graphene on a ferroelectric and resistivity of graphene channel were analyzed. Here, we develop a self-consistent approach combining the solution of electrostatic problems with the nonlinear Landau-Khalatnikov equations for a ferroelectric. The size-dependent behaviors are governed by the relations between the thicknesses of multilayer graphene, ferroelectric film, and the dielectric layer. The appearance of charge and electroresistance hysteresis loops and their versatility stem from the interplay of polarization reversal dynamics and its incomplete screening in an alternating electric field. These features are mostly determined by the dielectric layer thickness. The derived analytical expressions for electric fields and space-charge-density distribution in a multilayer system enable knowledge-driven design of graphene-on-ferroelectric heterostructures with advanced performance. We further investigate the effects of spatially nonuniform ferroelectric domain structures on the graphene layers' conductivity and predict its dramatic increase under the transition from multi- to single-domain state in a ferroelectric. This intriguing effect can open possibilities for the graphene-based sensors and explore the underlying physical mechanisms in the operation of graphene field-effect transistor with ferroelectric gating.

  12. First-principles theory, coarse-grained models, and simulations of ferroelectrics.

    PubMed

    Waghmare, Umesh V

    2014-11-18

    CONSPECTUS: A ferroelectric crystal exhibits macroscopic electric dipole or polarization arising from spontaneous ordering of its atomic-scale dipoles that breaks inversion symmetry. Changes in applied pressure or electric field generate changes in electric polarization in a ferroelectric, defining its piezoelectric and dielectric properties, respectively, which make it useful as an electromechanical sensor and actuator in a number of applications. In addition, a characteristic of a ferroelectric is the presence of domains or states with different symmetry equivalent orientations of spontaneous polarization that are switchable with large enough applied electric field, a nonlinear property that makes it useful for applications in nonvolatile memory devices. Central to these properties of a ferroelectric are the phase transitions it undergoes as a function of temperature that involve lowering of the symmetry of its high temperature centrosymmetric paraelectric phase. Ferroelectricity arises from a delicate balance between short and long-range interatomic interactions, and hence the resulting properties are quite sensitive to chemistry, strains, and electric charges associated with its interface with substrate and electrodes. First-principles density functional theoretical (DFT) calculations have been very effective in capturing this and predicting material and environment specific properties of ferroelectrics, leading to fundamental insights into origins of ferroelectricity in oxides and chalcogenides uncovering a precise picture of electronic hybridization, topology, and mechanisms. However, use of DFT in molecular dynamics for detailed prediction of ferroelectric phase transitions and associated temperature dependent properties has been limited due to large length and time scales of the processes involved. To this end, it is quite appealing to start with input from DFT calculations and construct material-specific models that are realistic yet simple for use in large-scale simulations while capturing the relevant microscopic interactions quantitatively. In this Account, we first summarize the insights obtained into chemical mechanisms of ferroelectricity using first-principles DFT calculations. We then discuss the principles of construction of first-principles model Hamiltonians for ferroelectric phase transitions in perovskite oxides, which involve coarse-graining in time domain by integrating out high frequency phonons. Molecular dynamics simulations of the resulting model are shown to give quantitative predictions of material-specific ferroelectric transition behavior in bulk as well as nanoscale ferroelectric structures. A free energy landscape obtained through coarse-graining in real-space provides deeper understanding of ferroelectric transitions, domains, and states with inhomogeneous order and points out the key role of microscopic coupling between phonons and strain. We conclude with a discussion of the multiscale modeling strategy elucidated here and its application to other materials such as shape memory alloys. PMID:25361389

  13. Observing the Superparaelectric Limit of Relaxor (Na1/2Bi1/2)0.9Ba0.1TiO3 Nanocrystals

    SciTech Connect

    Tiruvalam, Ram Chandra R [ORNL; Kundu, A. [Lehigh University, Bethlehem, PA; Soukhojak, A. [Lehigh University, Bethlehem, PA; Jesse, Stephen [ORNL; Kalinin, Sergei V [ORNL

    2006-09-01

    Applications of ferroelectric materials for nonvolatile memory, data storage devices, nanosensors, and nanoactuators necessitate fundamental studies of ferroelectric behavior, including the presence of switchable polarization and switching behavior, on the nanoscale. Here the authors investigated the switching properties of (Na{sub 1/2}Bi{sub 1/2}){sub 0.9}Ba{sub 0.1}TiO{sub 3} nanocrystals prepared by a mist deposition technique using piezoresponse force microscopy (PFM) and spectroscopy. By using stiff cantilevers, reliable PFM data have been obtained and local electromechanical response was measured. The transition from ferroelectric to superparaelectric behavior in these nanocrystals was observed at sizes of {approx}10 nm. The effects of particle shape on the PFM imaging are also discussed.

  14. Inorganic ceramic\\/polymer ferroelectric composite electrets

    Microsoft Academic Search

    C. J. Dias; D. K. Das-Gupta

    1996-01-01

    Ferroelectric composites are now an established alternative to conventional ferroelectric ceramic materials and to the more recently discovered ferroelectric polymers. These materials due to their unique blending of polymetric properties of mechanical flexibility, formability and low cost with high electro-active properties have been been suggested to be a viable alternative both in piezoelectric and pyroelectric transducer applications. This review is

  15. Ferroelectric Tunnel Memristor C.-W. Bark,

    E-print Network

    Eom, Chang Beom

    Ferroelectric Tunnel Memristor D. J. Kim, H. Lu, S. Ryu, C.-W. Bark, C.-B. Eom, E. Y. Tsymbal that is based on a ferroelectric tunnel junction, where the tunneling conductance can be tuned in an analogous. The ferroelectric tunnel memristors exhibit a reversible hysteretic nonvolatile resistive switching

  16. Optimization of Ferroelectric Ceramics by Design at the Microstructure Level

    SciTech Connect

    Jayachandran, K. P.; Guedes, J. M.; Rodrigues, H. C. [IDMEC-IST, Technical University of Lisbon, Mechanical Engineering, Av. Rovisco Pais, 1049-001 Lisbon (Portugal)

    2010-05-21

    Ferroelectric materials show remarkable physical behaviors that make them essential for many devices and have been extensively studied for their applications of nonvolatile random access memory (NvRAM) and high-speed random access memories. Although ferroelectric ceramics (polycrystals) present ease in manufacture and in compositional modifications and represent the widest application area of materials, computational and theoretical studies are sparse owing to many reasons including the large number of constituent atoms. Macroscopic properties of ferroelectric polycrystals are dominated by the inhomogeneities at the crystallographic domain/grain level. Orientation of grains/domains is critical to the electromechanical response of the single crystalline and polycrystalline materials. Polycrystalline materials have the potential of exhibiting better performance at a macroscopic scale by design of the domain/grain configuration at the domain-size scale. This suggests that piezoelectric properties can be optimized by a proper choice of the parameters which control the distribution of grain orientations. Nevertheless, this choice is complicated and it is impossible to analyze all possible combinations of the distribution parameters or the angles themselves. Hence we have implemented the stochastic optimization technique of simulated annealing combined with the homogenization for the optimization problem. The mathematical homogenization theory of a piezoelectric medium is implemented in the finite element method (FEM) by solving the coupled equilibrium electrical and mechanical fields. This implementation enables the study of the dependence of the macroscopic electromechanical properties of a typical crystalline and polycrystalline ferroelectric ceramic on the grain orientation.

  17. Nanoscale Ferroelectricity in Crystalline -Glycine

    SciTech Connect

    Meunier, Vincent [ORNL; Agarwal, Pratul K [ORNL; Sumpter, Bobby G [ORNL

    2012-01-01

    Ferroelectrics are multifunctional materials that reversibly change their polarization under an electric field. Recently, the search for new ferroelectrics has focused on organic and bio-organic materials, where polarization switching is used to record/retrieve information in the form of ferroelectric domains. This progress has opened a new avenue for data storage, molecular recognition, and new self-assembly routes. Crystalline glycine is the simplest amino acid and is widely used by living organisms to build proteins. Here, it is reported for the first time that {gamma}-glycine, which has been known to be piezoelectric since 1954, is also a ferroelectric, as evidenced by local electromechanical measurements and by the existence of as-grown and switchable ferroelectric domains in microcrystals grown from the solution. The experimental results are rationalized by molecular simulations that establish that the polarization vector in {gamma}-glycine can be switched on the nanoscale level, opening a pathway to novel classes of bioelectronic logic and memory devices.

  18. Ferroelectricity in undoped hafnium oxide

    NASA Astrophysics Data System (ADS)

    Polakowski, Patrick; Müller, Johannes

    2015-06-01

    We report the observation of ferroelectric characteristics in undoped hafnium oxide thin films in a thickness range of 4-20 nm. The undoped films were fabricated using atomic layer deposition (ALD) and embedded into titanium nitride based metal-insulator-metal (MIM) capacitors for electrical evaluation. Structural as well as electrical evidence for the appearance of a ferroelectric phase in pure hafnium oxide was collected with respect to film thickness and thermal budget applied during titanium nitride electrode formation. Using grazing incidence X-Ray diffraction (GIXRD) analysis, we observed an enhanced suppression of the monoclinic phase fraction in favor of an orthorhombic, potentially, ferroelectric phase with decreasing thickness/grain size and for a titanium nitride electrode formation below crystallization temperature. The electrical presence of ferroelectricity was confirmed using polarization measurements. A remanent polarization Pr of up to 10 ?C cm-2 as well as a read/write endurance of 1.6 × 105 cycles was measured for the pure oxide. The experimental results reported here strongly support the intrinsic nature of the ferroelectric phase in hafnium oxide and expand its applicability beyond the doped systems.

  19. The Soft Mode Driven Dynamics in Ferroelectric Perovskites at the Nanoscale: An Atomistic Study

    NASA Astrophysics Data System (ADS)

    McCash, Kevin

    The discovery of ferroelectricity at the nanoscale has incited a lot of interest in perovskite ferroelectrics not only for their potential in device application but also for their potential to expand fundamental understanding of complex phenomena at very small size scales. Unfortunately, not much is known about the dynamics of ferroelectrics at this scale. Many of the widely held theories for ferroelectric materials are based on bulk dynamics which break down when applied to smaller scales. In an effort to increase understanding of nanoscale ferroelectric materials we use atomistic resolution computational simulations to investigate the dynamics of polar perovskites. Within the framework of a well validated effective Hamiltonian model we are able to accurately predict many of the properties of ferroelectric materials at the nanoscale including the response of the soft mode to mechanical boundary conditions and the polarization reversal dynamics of ferroelectric nanowires. Given that the focus of our study is the dynamics of ferroelectric perovskites we begin by developing an effective Hamiltonian based model that could simultaneously describe both static and dynamic properties of such materials. Our study reveals that for ferroelectric perovskites that undergo a sequence of phase transitions, such as BaTiO3. for example, the minimal parameter effective Hamiltonian model is unable to reproduce both static and dynamical properties simultaneously. Nevertheless we developed two sets of parameters that accurately describes the static properties and dynamic properties of BaTiO3 independently. By creating a tool that accurately models the dynamical properties of perovskite ferroelectrics we are able to investigate the frequencies of the soft modes in the perovskite crystal. The lowest energy transverse optical soft modes in perovskite ferroelectrics are known to be cause of the ferroelectric phase transition in these materials and affect a number of electrical properties. The performance of a ferroelectric device is therefore directly influenced by the dynamics of the soft mode. Interestingly, however, little study has been done on the effect of mechanical boundary conditions on the soft modes of perovskites. Understanding the effect of mechanical forces on the soft modes is critical to device applications as complicated growth structures often are the cause of pressures, stresses and strains. Using classical molecular dynamics we study the effect of hydrostatic pressure, uniaxial stress, biaxial stress and biaxial strain on the soft modes of the ferroelectric PbTiO 3. The results of this study indicate the existence of Curie-Weiss laws for not only hydrostatic pressure, which is well known, but also for uniaxial stress, biaxial stress and biaxial strain. The mode frequencies are also seen to respond very differently to these mechanical forces and lead to a more complete picture of the behavior of nanoscale ferroelectrics. One nanoscale geometry of perovskite ferroelectrics is the pseudo one-dimensional nanowire. These structures have very unique properties that are highly attractive for use as interconnects, nanoscale sensors or more directly in computer memory devices. Perovskite nanowires have only recently been synthesized and the techniques are not well developed. While progress has been made towards consistently fabricating uniform, high quality nanowires experimental investigation of their properties is prohibitively difficult. Of immediate interest is the polarization reversal dynamics of ferroelectric nanowires. The reading and writing of bits of information stored in a wire's polarization state is done by switching the polarization. Again using classical molecular dynamics we study the polarization reversal dynamics in ferroelectric nanowires made of Pb(Ti1-xZrx)O 3 disordered alloy. We find that there are two competing mechanisms for polarization reversal and that the interplay of these mechanisms is dependent on electric field strength. The dynamics in nanowires also sheds light on long standing theories about polar

  20. Emission from ferroelectric cathodes

    NASA Astrophysics Data System (ADS)

    Sampayan, S. E.; Caporaso, G. J.; Holmes, C. L.; Lauer, E. J.; Prosnitz, D.; Trimble, D. O.; Westenskow, G. A.

    1993-05-01

    The authors have recently initiated an investigation of electron emission from ferroelectric cathodes. The experimental apparatus consisted of an electron diode and a 250 kV, 12 ohm, 70 ns pulsed high voltage power source. A planar triode modulator driven by a synthesized waveform generator initiates the polarization inversion and allows inversion pulse tailoring. The pulsed high voltage power source is capable of delivering two high voltage pulses within 50 (mu)s of each other and is capable of operating at a sustained repetition rate of 5 Hz. The initial measurements indicate that emission current densities above the Child-Langmuir Space Charge Limit, J(sub CL), are possible. They explain this effect to be based on a non-zero initial energy of the emitted electrons. They also determined that this effect is strongly coupled to relative timing between the inversion pulse and application of the main anode-cathode pulse. They also have initiated brightness measurements of the emitted beam and estimate a preliminary lower bound to be on the order of 10(exp 9) A/sq m-rad(exp 2) for currents close to J(sub CL) and factor of two less at currents over 4J(sub CL). As in previous measurements at this laboratory, they performed the measurement using a pepper pot technique. Beamlet profiles are recorded with a fast phosphor and gated cameras. They describe their apparatus and preliminary measurements.

  1. Emission from ferroelectric cathodes

    SciTech Connect

    Sampayan, S.E.; Caporaso, G.J.; Holmes, C.L.; Lauer, E.J.; Prosnitz, D.; Trimble, D.O.; Westenskow, G.A.

    1993-05-17

    We have recently initiated an investigation of electron emission from ferroelectric cathodes. Our experimental apparatus consisted of an electron diode and a 250 kV, 12 ohm, 70 ns pulsed high voltage power source. A planar triode modulator driven by a synthesized waveform generator initiates the polarization inversion and allows inversion pulse tailoring. The pulsed high voltage power source is capable of delivering two high voltage pulses within 50 ns of each other and is capable of operating at a sustained repetition rate of 5 Hz. Our initial measurements indicate that emission current densities above the Child-Langmuir Space Charge Limit are possible. We explain this effect to be based on a non-zero initial energy of the emitted electrons. We also determined that this effect is strongly coupled to relative timing between the inversion pulse and application of the main anode-cathode pulse. We also have initiated brightness measurements of the emitted beam. As in our previous measurements at this Laboratory, we performed the measurement using a pepper pot technique. Beam-let profiles are recorded with a fast phosphor and gated cameras. We describe our apparatus and preliminary measurements.

  2. Emission from ferroelectric cathodes

    NASA Astrophysics Data System (ADS)

    Sampayan, S. E.; Caporaso, G. J.; Holmes, C. L.; Lauer, E. J.; Prosnitz, D.; Trimble, D. O.; Westenskow, G. A.

    1994-02-01

    We have recently initiated an investigation of electron emission from ferroelectric cathodes. Our experimental apparatus consisted of an electron diode and a 250 kV, 12 ?, 70 ns pulsed high voltage power source. A planar triode modulator driven by a synthesized waveform generator initiates the polarization inversion and allows inversion pulse tailoring. The pulsed high voltage power source is capable of delivering two high voltage pulses within 50 ?s of each other and is capable of operating at a sustained repetition rate of 5 Hz. Our initial measurements indicate that emission current densities above the Child-Langmuir space charge limit, JCL, are possible. We explain this effect to be based on a non-zero initial energy of the emitted electrons. We also determined that this effect is strongly coupled to relative timing between the inversion pulse and application of the main anode-cathode pulse. We also have initiated brightness measurements of the emitted beam and estimate a preliminary lower bound to be on the order of 10 9 A/m 2rad 2. As in our previous measurements at this Laboratory, we performed the measurement using a pepper pot technique. Beamlet profiles are recorded with a fast phosphor and gated cameras. We describe our apparatus and preliminary measurements.

  3. Transmission properties of metal-semiconductor-relaxor microstrip lines

    Microsoft Academic Search

    HCctor H. Fiallo; Joseph P. Dougherty; Sei-Joo Jang; R. E. Newnham; L. A. Carpenter

    1994-01-01

    The transmission characteristics of multilayer ferrite-high-K microstrip lines have been calculated by means of the parallel-plate waveguide approximation. The relaxation behavior of the dielectric permittivity and permeability have been taken into account by using the Debye and the Maxwell-Wagner relaxation models. The results demonstrate that these lines can be used as very small size delay lines and low-pass filters that

  4. Low electric-field driven ultrahigh electrostrains in Sb-substituted (Na,K)NbO3 lead-free ferroelectric ceramics

    NASA Astrophysics Data System (ADS)

    Fu, Jian; Zuo, Ruzhong; Qi, He; Zhang, Chen; Li, Jingfeng; Li, Longtu

    2014-12-01

    Lead-free (Na0.52K0.48)(Nb1-ySby)O3 (NKNSy) ferroelectric ceramics were reported to exhibit an ultrahigh electrostrain (dynamic d33* (=S/E) of 800-1100 pm/V) in a relatively low driving electric field range (1-4 kV/mm). As evidenced by in-situ synchrotron x-ray diffraction and dielectric measurements, the mechanism of generating large strains was ascribed to both the low-field induced reversible rhombohedral-monoclinic phase transition (1-2 kV/mm) and the enhanced domain switching (2-4 kV/mm) owing to the normal to relaxor phase transformation, which contribute to ˜62% and ˜38% of the total strain, respectively. The results indicate that the NKNSy compositions would have excellent potentials for applications of lead-free actuator ceramics.

  5. Elastocaloric effect in ferroelectric ceramics

    NASA Astrophysics Data System (ADS)

    Chauhan, Aditya; Patel, Satyanarayan; Vaish, Rahul

    2015-04-01

    Elastocaloric effect has been experimentally demonstrated in bulk (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 polycrystalline ferroelectric material. Predictions were made using Maxwell's relationship for elastocaloric effect. A maximum elastocaloric effect of 1.55 K was observed for an initial material temperature of 340 K and applied compressive stress of 0-250 MPa (under a constant electric field of 2 MV m-1). The reported value is several times larger than the peak electrocaloric effect for the same material. The results indicate that ferroelectric materials possess a huge potential for elastocaloric refrigeration.

  6. Coulomb Microexplosions of Ferroelectric Ceramics

    SciTech Connect

    Yarmolich, D.; Vekselman, V.; Gurovich, V. Tz.; Krasik, Ya. E. [Physics Department, Technion, 32000 Haifa (Israel)

    2008-02-22

    Energetic neutral and extreme ultraviolet emission initiated by the dense plasma propagation along a ferroelectric surface has been found. It was shown that the emission of neutrals is characterized by a large divergence and velocities up to 7x10{sup 7} cm/s. This phenomenon is explained by an extremely large electric field with amplitude {>=}10{sup 6} V/cm and rise time {approx}10{sup -10} s which appears at the plasma front due to the fast fall in the driving pulse. This electric field causes microexplosions of the ferroelectric surface due to inertia in the ion polarization response.

  7. Ferroelectric Fluid Flow Control Valve

    NASA Technical Reports Server (NTRS)

    Jalink, Antony, Jr. (Inventor); Hellbaum, Richard F. (Inventor); Rohrbach, Wayne W. (Inventor)

    1999-01-01

    An active valve is controlled and driven by external electrical actuation of a ferroelectric actuator to provide for improved passage of the fluid during certain time periods and to provide positive closure of the valve during other time periods. The valve provides improved passage in the direction of flow and positive closure in the direction against the flow. The actuator is a dome shaped internally prestressed ferroelectric actuator having a curvature, said dome shaped actuator having a rim and an apex. and a dome height measured from a plane through said rim said apex that varies with an electric voltage applied between an inside and an outside surface of said dome shaped actuator.

  8. Investigation of the seeding-layer effect for a ferroelectric thin film with the transverse Ising model

    NASA Astrophysics Data System (ADS)

    Wang, Chundong; Teng, Baohua; Zhang, Xianjun; Lu, Zhaoxin; Liu, Liwei; Cheng, Dengmu; Lu, Xiaohua

    2009-04-01

    The transition feature of a ferroelectric thin film with a seeding layer is studied based on the transverse Ising model. The influence of the seeding layer on the transition behavior of a ferroelectric thin film is investigated systemically, and the effect of the interaction parameters for the seeding layer on the phase diagram is also obtained. Meanwhile, the polarization and Curie temperature of the ferroelectric thin film are calculated for different seeding-layer structures. The results show that the polarization and Curie temperature of the film will be obviously modified on adding a seeding layer.

  9. High-frequency programmable acoustic wave device realized through ferroelectric domain engineering

    SciTech Connect

    Ivry, Yachin, E-mail: ivry@mit.edu, E-mail: cd229@eng.cam.ac.uk; Wang, Nan; Durkan, Colm, E-mail: ivry@mit.edu, E-mail: cd229@eng.cam.ac.uk [Nanoscience Centre, University of Cambridge, 11 JJ Thomson Avenue, Cambridge CB3 0FF (United Kingdom)

    2014-03-31

    Surface acoustic wave devices are extensively used in contemporary wireless communication devices. We used atomic force microscopy to form periodic macroscopic ferroelectric domains in sol-gel deposited lead zirconate titanate, where each ferroelectric domain is composed of many crystallites, each of which contains many microscopic ferroelastic domains. We examined the electro-acoustic characteristics of the apparatus and found a resonator behavior similar to that of an equivalent surface or bulk acoustic wave device. We show that the operational frequency of the device can be tailored by altering the periodicity of the engineered domains and demonstrate high-frequency filter behavior (>8?GHz), allowing low-cost programmable high-frequency resonators.

  10. Ferromagnetism and ferroelectric properties of (Mn, Li) co-doped ZnO nanorods arrays deposited by electrodeposition

    Microsoft Academic Search

    C. W. Zou; L. X. Shao; L. P. Guo; D. J. Fu; T. W. Kang

    2011-01-01

    One dimensional (Mn, Li) co-doped ZnO nanorods have been prepared using electrodeposition method at constant current mode. Room temperature ferromagnetism and ferroelectricity were found coexisted in the co-doped ZnO nanorods and the underlying mechanism were discussed. The origin of the ferroelectric behavior could be explained on the basis of the ionic radii difference between the Zn2+ (0.74Å) and the dopants

  11. Ferromagnetism and ferroelectric properties of (Mn, Li) co-doped ZnO nanorods arrays deposited by electrodeposition

    Microsoft Academic Search

    C. W. Zou; L. X. Shao; L. P. Guo; D. J. Fu; T. W. Kang

    2011-01-01

    One dimensional (Mn, Li) co-doped ZnO nanorods have been prepared using electrodeposition method at constant current mode. Room temperature ferromagnetism and ferroelectricity were found coexisted in the co-doped ZnO nanorods and the underlying mechanism were discussed. The origin of the ferroelectric behavior could be explained on the basis of the ionic radii difference between the Zn 2+ (0.74 Å) and

  12. Piezoresponse through a ferroelectric nanotube wall

    NASA Astrophysics Data System (ADS)

    Nonnenmann, Stephen S.; Gallo, Eric M.; Coster, Michael T.; Soja, Gregory R.; Johnson, Craig L.; Joseph, Rahul S.; Spanier, Jonathan E.

    2009-12-01

    We report on the controlled local switching and imaging of local ferroelectric polarizations oriented perpendicular to the long axis of a lead zirconate titanate (PZT) nanotube. Piezoresponse force microscopy and ferroelectric piezoelectric hysteresis data indicate stable polarizations oriented along the radial, finite-thickness direction can be formed in a nanoshell geometry. The results of infrared spectroscopy and of the character of as-found polarizations are consistent with recent findings linking surface chemical environment to ferroelectric stability and to orientation of ferroelectric polarizations.

  13. Unusual phenomena in ferroelectric nanostructures

    NASA Astrophysics Data System (ADS)

    Prosandeev, Sergey

    2007-03-01

    First-principles based computations are nowadays capable of tackling really complex challenges of fundamental and technological importance. For example, a dipole vortex structure has been discovered, by means of these methods, in isolated nanoparticles of ferroelectrics --which may lead to a new generation of efficient nanoscale memory devices [1]. Here, we use first-principles-based approaches to address the following issues: (i) what are the elastic signatures and field charateristics of dipole vortices in isolated ferroelectric nanodots? (ii) how to control the chirality of such dipole vortices (which is an important challenge to solve for future applications)? and (iii) what are the possible ground states of arrays of ferroelectric dots embedded in a crystal lattice? Regarding item (i), we found that the tetragonal axial ratio in the vortex state is lower than 1 (unlike in ``normal'' ferroelectric or antiferrodistortive phases), and that the electric field produced by the dipole vortex outside the dot oscillates in space when changing the polar angle of the cylindrical coordinate system. Such features can serve as fingerprints of the vortex state to experimentally confirm the existence of such unusual state. Moreover, we demonstrate that, and explain why, using inhomogeneous electric fields is an efficient solution to item (ii) [2]. Finally, it is predicted that array of embedded dots can adopt new phases, depending on the temperature and difference in polarizability between the dots and medium [3]. Atomistic details of such phases, as well as their governing mechanisms, will be provided. Coauthors: I. Ponomareva, I. Kornev, I. Naumov, and L. Bellaiche, University of Arkansas. [1] I. Naumov, L. Bellaiche, & H. Fu. ``Unusual phase transitions in ferroelectric nanodisks and nanorods, '' Nature 432, 737 (2004). [2] S. Prosandeev, I. Ponomareva, I. Kornev, I. Naumov, & L. Bellaiche. ``Controlling toroidal moment by means of an inhomogeneous static field: an ab initio study,'' Phys. Rev. Lett. 96, 237601-1-4 (2006). [3] S. Prosandeev & L. Bellaiche. ``Properties of ferroelectric nanodots embedded in a polarizable medium: atomistic simulations.,'' Phys. Rev. Lett. 97, 167601 (2006).

  14. Artificial ferroelectricity in perovskite superlattices

    NASA Astrophysics Data System (ADS)

    Tsurumi, Takaaki; Harigai, Takakiyo; Tanaka, Daisuke; Nam, Song-Min; Kakemoto, Hirofumi; Wada, Satoshi; Saito, Keisuke

    2004-11-01

    Artificial superlattices of SrZrO3(SZO)/SrTiO3(STO ) were fabricated by molecular-beam epitaxy. Lattice parameters showed that the lattice distortion (c /a ratio) attained a maximum value in the [(SZO)10/(STO)10]4 superlattice. Dielectric relaxation was observed in the [(SZO)1/(STO)1]40 and [(SZO)10/(STO)10]4 superlattices in the low frequency domain. Dielectric permittivity of the SZO /STO superlattices was over 10 000 at 110MHz. The SZO /STO superlattices showed clear Q -V hysteresis curves, which indicated that ferroelectricity was induced artificially in the superlattices in spite of the paraelectric nature of SZO and STO. The origin of the ferroelectricity was related to the anisotropic lattice distortion in the superlattice structure.

  15. Ferroelectric Stirling-Cycle Refrigerator

    NASA Technical Reports Server (NTRS)

    Jalink, Antony, Jr. (Inventor); Hellbaum, Richard F. (Inventor); Rohrbach, Wayne W. (Inventor)

    1999-01-01

    A Stirling-cycle refrigerator has a three-pump configuration and pumping sequence, in which one pump serves as a compressor. one pump serves as an expander, and one pump serves as a displacer. The pumps are ferroelectrically actuated diaphragm pumps which are coordinated by synchronizing the ferroelectric-actuator voltages in such a way that the net effect of the displacer is to reduce the deleterious effect of dead space; that is, to circulate a greater fraction of the working fluid through the heat exchangers than would be possible by use of the compressor and expander alone. In addition. the displacer can be controlled separately to make the flow of working fluid in the heat exchangers turbulent (to increase the rate of transfer of heat at the cost of greater resistance to flow) or laminar (to decrease the resistance to flow at the cost of a lower heat-transfer rate).

  16. Kinetics of Ferroelectric Phase Transition: Nonlinear Pyroelectric Effect and Ferroelectric Solar Cell

    NASA Astrophysics Data System (ADS)

    Itskovsky, M.

    1999-08-01

    Kinetics of a ferroelectric phase transition in thin ferroelectric layer (film), coated with metallic films [metal-ferroelectric-metal (MFM) system] and overheated with various heating rates through phase transition temperature by solar or laser irradiation impulse, is investigated. Dynamical nonlinear pyroelectric effect (pyroelectric current and polarization) as well as anomalies of dielectric permittivity and specific heat are calculated as functions of changing in time temperature for various heating rates. Conversion efficiency during heating of the MFM system (served as ferroelectric solar cell), operating due to the nonlinear pyroelectric effect in the ferroelectric phase transition region, ranges from a few percent for ferroelectrics of the triglycine sulphate (TGS) type to above 10% for the NaNO2 type ferroelectrics, reaching the order of efficiency of photovoltaic solar cell.

  17. Surface atomic and chemical structure of relaxor Sr0.63Ba0.37Nb2O6(001)

    NASA Astrophysics Data System (ADS)

    Wang, J. L.; Vilquin, B.; Gautier, B.; Dezanneau, G.; Barrett, N.

    2015-06-01

    The surface atomic and chemical structures of a Sr0.63Ba0.37Nb2O6(001) single crystal are studied using the low-energy electron diffraction (LEED) and X-ray photoelectron spectroscopy. Sharp, well-defined LEED patterns are observed, consisting of the superposition of two surface reconstructions, ( ?{ 5 } × ?{ 5 } )R26.6° and ( 5 ?{ 2 } × ?{ 2 } )R45°, probably due to long-range ordering of the alkaline earth metal vacancies in A1 or A2 sites. The Sr/Ba stoichiometry is determined by high-resolution X-ray photoelectron spectroscopy. The Sr 3d core level has 2 components corresponding to the 12- and 15-fold coordinated A1 and A2 sites. The Ba 3d core level has only one component, consistent with the A2 site occupancy. The long-range order of the cation vacancies implies that it is rather the Sr/Ba occupancy of the A2 sites which is responsible for the local random fields at the origin of the relaxor behavior.

  18. High Temperature Ferroelectrics for Actuators: Recent Developments and Challenges

    NASA Technical Reports Server (NTRS)

    Sehirlioglu, Alp; Kowalski, Benjamin

    2014-01-01

    A variety of piezoelectric applications have been driving the research in development of new high temperature ferroelectrics; ranging from broader markets such as fuel and gas modulation and deep well oil drilling to very specific applications such as thermoacoustic engines and ultrasonic drilling on the surface of Venus. The focus has been mostly on increasing the Curie temperature. However, greater challenges for high temperature ferroelectrics limit the operating temperature to levels much below the Curie temperature. These include enhanced loss tangent and dc conductivity at high fields as well as depoling due to thermally activated domain rotation. The initial work by Eitel et al. [Jpn. J. Appl. Phys., 40 [10, Part 1] 59996002 (2001)] increased interest in investigation of Bismuth containing perovskites in solid solution with lead titanate. Issues that arise vary from solubility limits to increased tetragonality; the former one prohibits processing of morphotropic phase boundary, while the latter one impedes thorough poling of the polycrystalline ceramics. This talk will summarize recent advances in development of high temperature piezoelectrics and provide information about challenges encountered as well as the approaches taken to improve the high temperature behavior of ferroelectrics with a focus on applications that employ the converse piezoelectric effect.

  19. Monte Carlo simulation of quantum effects in ferroelectric phase transitions with increasing zero point energy

    Microsoft Academic Search

    C. L Wang; J. Garcia; C. Aragó; J. A Gonzalo; M. I. Marqués

    2002-01-01

    The Ising model in a transverse field has been used for a long time to describe ferroelectric phase transitions. Quantum tunneling and zero point energy effects in double potential wells have been shown recently to give rise to analogous behavior at the phase transitions. In this work we show that Monte Carlo simulations of the temperature dependence of the order

  20. Anomaly in the conductivity relaxation parameters at the phase transition of ferroelectric materials: A time domain study

    SciTech Connect

    Leyet, Y.; Guerrero, F. [Departamento de Fisica, Facultad de Ciencias Naturales, Universidad de Oriente, CP-90500, Santiago de Cuba (Cuba); Amorin, H. [Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, 28049 Madrid (Spain); Guerra, J. de Los S. [Instituto de Fisica, Universidade Federal de Uberlandia (UFU), 38400-902 Uberlandia, Minas Gerais Brazil (Brazil); Eiras, J. A. [Departamento de Fisica, Grupo de Ceramicas Ferroeletricas, Universidade Federal de Sao Carlos (UFSCar), CEP 13565-670 Sao Carlos, Sao Paulo (Brazil)

    2010-10-18

    The influence of the ferroelectric to paraelectric transition on the relaxation parameters of conductive processes in ferroelectric materials is studied in the time domain. Three well-known ferroelectric systems were chosen with transition temperatures in different regions, these are, high-temperature PbNb{sub 2}O{sub 6}-based ceramics; nanostructured Pb(Zr{sub 0.6}Ti{sub 0.4})O{sub 3} ceramics; and submicron BaTiO{sub 3}. The thermal evolution of relaxation parameters shows clear anomalies in their typical behavior when conductivity processes arise in the temperature range where the ferroelectric transition takes place. The method here described allows obtaining information about the correlation between charge transport and the motion of the off-center ions at the phase transition.

  1. Domain switching in polycrystalline ferroelectric ceramics

    Microsoft Academic Search

    J. Y. Li; R. C. Rogan; E. Üstündag; K. Bhattacharya

    2005-01-01

    Ferroelectric ceramics are widely used as sensors and actuators for their electro-mechanical properties, and in electronic applications for their dielectric properties. Domain switching – the phenomenon wherein the ferroelectric material changes from one spontaneously polarized state to another under electrical or mechanical loads – is an important attribute of these materials. However, this is a complex collective process in commercially

  2. Ferroelectric translational antiphase boundaries in nonpolar materials.

    PubMed

    Wei, Xian-Kui; Tagantsev, Alexander K; Kvasov, Alexander; Roleder, Krystian; Jia, Chun-Lin; Setter, Nava

    2014-01-01

    Ferroelectric materials are heavily used in electro-mechanics and electronics. Inside the ferroelectric, domain walls separate regions in which the spontaneous polarization is differently oriented. Properties of ferroelectric domain walls can differ from those of the domains themselves, leading to new exploitable phenomena. Even more exciting is that a non-ferroelectric material may have domain boundaries that are ferroelectric. Many materials possess translational antiphase boundaries. Such boundaries could be interesting entities to carry information if they were ferroelectric. Here we show first that antiphase boundaries in antiferroelectrics may possess ferroelectricity. We then identify these boundaries in the classical antiferroelectric lead zirconate and evidence their polarity by electron microscopy using negative spherical-aberration imaging technique. Ab initio modelling confirms the polar bi-stable nature of the walls. Ferroelectric antiphase boundaries could make high-density non-volatile memory; in comparison with the magnetic domain wall memory, they do not require current for operation and are an order of magnitude thinner. PMID:24398704

  3. Multiferroics: a magnetic twist for ferroelectricity

    Microsoft Academic Search

    Sang-Wook Cheong; Maxim Mostovoy

    2007-01-01

    Magnetism and ferroelectricity are essential to many forms of current technology, and the quest for multiferroic materials, where these two phenomena are intimately coupled, is of great technological and fundamental importance. Ferroelectricity and magnetism tend to be mutually exclusive and interact weakly with each other when they coexist. The exciting new development is the discovery that even a weak magnetoelectric

  4. Ferroelectric Liquid Crystal Conglomerates DAVID M. WALBA

    E-print Network

    Walba, David

    Liquid Crystals from Achiral Molecules: Banana Phases 6.1 Bilayer Smectics and First Achiral Antiferroelectric LC 6.2 Bent-Core Mesogens 6.3 Matsunaga Diesters 6.4 Banana Mania 6.5 B4 Phase 6.6 B2 Phase.10 Ferroelectric Banana by Design 6.11 Ferroelectric "Macroscopic Racemate" from Unichiral Mesogen 7 Conclusion

  5. Ferroelectric translational antiphase boundaries in nonpolar materials

    PubMed Central

    Wei, Xian-Kui; Tagantsev, Alexander K.; Kvasov, Alexander; Roleder, Krystian; Jia, Chun-Lin; Setter, Nava

    2014-01-01

    Ferroelectric materials are heavily used in electro-mechanics and electronics. Inside the ferroelectric, domain walls separate regions in which the spontaneous polarization is differently oriented. Properties of ferroelectric domain walls can differ from those of the domains themselves, leading to new exploitable phenomena. Even more exciting is that a non-ferroelectric material may have domain boundaries that are ferroelectric. Many materials possess translational antiphase boundaries. Such boundaries could be interesting entities to carry information if they were ferroelectric. Here we show first that antiphase boundaries in antiferroelectrics may possess ferroelectricity. We then identify these boundaries in the classical antiferroelectric lead zirconate and evidence their polarity by electron microscopy using negative spherical-aberration imaging technique. Ab initio modelling confirms the polar bi-stable nature of the walls. Ferroelectric antiphase boundaries could make high-density non-volatile memory; in comparison with the magnetic domain wall memory, they do not require current for operation and are an order of magnitude thinner. PMID:24398704

  6. Electric field induced short range to long range structural ordering and its influence on the Eu+3 photoluminescence in the lead-free ferroelectric Na1/2Bi1/2TiO3

    NASA Astrophysics Data System (ADS)

    Kalaskar, Abhijeet; Rao, Badari Narayana; Thomas, Tiju; Ranjan, Rajeev

    2015-06-01

    Eu+3 was incorporated into the lattice of a lead-free ferroelectric Na1/2Bi1/2TiO3 (NBT) as per the nominal formula Na0.5Bi0.5-xEuxTiO3. This system was investigated with regard to the Eu+3 photoluminescence (PL) and structural behaviour as a function of composition and electric field. Electric field was found to irreversibly change the features in the PL spectra and also in the x-ray diffraction patterns below the critical composition x = 0.025. Detailed analysis revealed that below the critical composition, electric field irreversibly suppresses the structural heterogeneity inherent of the host matrix NBT and brings about a long range ferroelectric state with rhombohedral (R3c) distortion. It is shown that the structural disorder on the nano-scale opens a new channel for radiative transition which manifests as a new emission line branching off from the main 5D0?7F0 line along with a concomitant change in the relative intensity of the other crystal field induced Stark lines with different J values. The study suggests that Eu+3 luminescence can be used to probe the relative degree of field induced structural ordering in relaxor ferroelectrics and also in high performance piezoelectric alloys where electric field couples very strongly with the lattice and structural degrees of freedom.

  7. Effects of the spontaneous polarization on the structural and dynamic properties of ferroelectric liquid crystals

    NASA Astrophysics Data System (ADS)

    Coleman, David Anthony

    2002-08-01

    The creation, nearly 30 years ago, of chiral tilted smectic liquid crystals produced spontaneous polar order in a fluid for the first time. Unlike solid-state ferrolectrics in which the polarization is restricted by the symmetry of a crystal lattice, ferroelectric smectics can freely orient in two dimensions. Consequently, the liquid crystal polarization is extremely sensitive to interactions with external boundaries, electric field, and its own intrisic polarity. Optical and x-ray techniques have been used to study these interactions in the following three cases. Total Internal Reflection is used to probe the molecular organization at the interface between a solid substrate and a tilted chiral smectic liquid crystal at temperatures in the vicinity of the bulk antiferroelectric-ferroelectric phase transition. Optical reflectivity data are interpreted using an exact analytical solution of a real model for ferroelectric order at the surface. We discuss the conditions for polar order at the surface, and then demonstrate that in the mixture T3, ferroelectric surface order is expelled below the bulk ferroelectric-antiferroelectric transition. The continuously reorientable (XY-like) ferroelectric polarization density of a chiral smectic liquid crystal is shown experimentally to produce nearly complete screening of the applied electric field in an appropriate cell geometry. This screening, combined with the expulsion of polarization charge for large polarization materials, leads to semiconducting electrical behavior of the otherwise insulating liquid crystal and electrostatic control of the orientation of a uniform optic axis/polarization field. Finally, we determine the structure of an achiral ferroelectric liquid crystal in which the polarization spontaneously produces a periodically splayed structure. The structure of the smectic layers is determined by x-ray diffraction and the molecular order within the layers is deduced from polarized optical microscopy observations. On the basis of the x-ray measurements, we are able to differentiate between two optically-similar phases.

  8. Pressure tuned ferroelectric reentrance in nano-BaTiO{sub 3} ceramics

    SciTech Connect

    Zhu, J. L.; Lin, S.; Feng, S. M.; Wang, L. J.; Liu, Q. Q.; Jin, C. Q. [Institute of Physics, Chinese Academy of Sciences, P.O. Box 603, Beijing 100190 (China); Wang, X. H.; Zhong, C. F.; Li, L. T. [Department of Materials Sciences, Tsinghua University, Beijing 100084 (China); Cao, Wenwu [Materials Research Institute, Pennsylvania State University, University Park, Pennsylvania 16802 (United States)

    2012-12-15

    In nano-grain BaTiO{sub 3} ceramics, internal compressive stresses make the cubic phase more stable, while internal shear stresses stabilize rhombohedral and orthorhombic phases. The competition between internal compressive stresses and internal shear stresses gives a ferroelectric to paraelectric to ferroelectric reentrance phenomenon as a function of grain size. The pressure can be a tuning factor of reentrance behavior by controlling the interactions between external hydrostatic pressure and internal compressive stresses. These experimental phenomena can be well described by a modified Ginzburg-Landau-Devonshire thermodynamic theory.

  9. Polarization relaxation induced by a depolarization field in ultrathin ferroelectric capacitors.

    PubMed

    Kim, D J; Jo, J Y; Kim, Y S; Chang, Y J; Lee, J S; Yoon, Jong-Gul; Song, T K; Noh, T W

    2005-12-01

    Time-dependent polarization relaxation behavior induced by a depolarization field E(d) was investigated on high-quality ultrathin SrRuO3/BaTiO3/SrRuO3 capacitors. The E(d) values were determined experimentally from an applied external field to stop the net polarization relaxation. These values agree with those from the electrostatic calculations, demonstrating that a large E(d) inside the ultrathin ferroelectric layer could cause severe polarization relaxation. For numerous ferroelectric devices of capacitor configuration, this effect will set a stricter size limit than the critical thickness issue. PMID:16384347

  10. Ferroelectric Superlattices as a route to clean Graphene-ferroelectric Interfaces

    NASA Astrophysics Data System (ADS)

    Yusuf, Mohammed; Dawber, Matthew; Du, Xu

    2014-03-01

    A good interface between ferroelectric surfaces and graphene sheets can enable a new generation of multifunctional devices in which the ferroelectric material is used to control the properties of graphene. Ferroelectric superlattices, in particular PbTiO3/SrTiO3 (PTO/STO), provide us with a unique opportunity for studying the graphene-ferroelectric interface. The ferroelectric-paraelectric transition temperature of the superlattices is tunable by varying the PTO volume fraction. Using devices with different PTO volume fractions and different ferroelectric strength, we have successfully demonstrated ferroelectric hysteresis, charge-trapping associated anti-hysteresis, and cross-over from anti-hysteresis to hysteresis over a wide temperature range from 300K down to 4K. These results allow us to establish a deeper understanding of the graphene-ferroelectric interface. Contrary to the common understandings that the charge trapping centers and anti-hysteresis originate mainly from contaminants and adsorbates trapped between graphene and ferroelectric substrates during fabrication, we found that significant contribution of charge trapping may come from defects in the ferroelectric substrate itself, and we explore approaches to eliminating these. This work was supported by NSF (Grant : DMR 1105202). Part of this research was carried out at the Center for Functional Nanomaterials, Brookhaven National Laboratory.

  11. Thin Layer Composite Unimorph Ferroelectric Driver and Sensor

    NASA Technical Reports Server (NTRS)

    Hellbaum, Richard F. (Inventor); Bryant, Robert G. (Inventor); Fox, Robert L. (Inventor)

    1997-01-01

    A method for forming ferroelectric wafers is provided. A prestress layer is placed on the desired mold. A ferroelectric wafer is placed on top of the prestress layer. The layers are heated and then cooled causing the ferroelectric wafer to become prestressed. The prestress layer may include reinforcing material and the ferroelectric wafer may include electrodes or electrode layers may be placed on either side of the ferroelectric layer. Wafers produced using this method have greatly improved output motion.

  12. Thin Layer Composite Unimorph Ferroelectric Driver and Sensor

    NASA Technical Reports Server (NTRS)

    Helbaum, Richard F. (inventor); Bryant, Robert G. (inventor); Fox, Robert L. (inventor); Jalink, Antony, Jr. (inventor); Rohrbach, Wayne W. (inventor); Simpson, Joycelyn O. (inventor)

    1995-01-01

    A method for forming ferroelectric wafers is provided. A prestress layer is placed on the desired mold. A ferroelectric wafer is placed on top of the prestress layer. The layers are heated and then cooled, causing the ferroelectric wafer to become prestressed. The prestress layer may include reinforcing material and the ferroelectric wafer may include electrodes or electrode layers may be placed on either side of the ferroelectric layer. Wafers produced using this method have greatly improved output motion.

  13. Ferroelectric and electrical characterization of multiferroic BiFeO3 at the single nanoparticle level

    SciTech Connect

    Vasudevan, Rama K [ORNL; Bogle, K A [University of New South Wales, Sydney, Australia; Kumar, Amit [ORNL; Jesse, Stephen [ORNL; Magaraggia, R [University of Glasgow; Stamps, R [University of Glasgow; Ogale, S [National Chemical Laboratory, India; Potdar, H S [National Chemical Laboratory, India

    2011-01-01

    Ferroelectric BiFeO3 (BFO) nanoparticles deposited on epitaxial substrates of SrRuO3 (SRO) and La1xSrxMnO3 (LSMO) were studied using band excitation piezoresponse spectroscopy (BEPS), piezoresponse force microscopy (PFM), and ferromagnetic resonance (FMR). BEPS confirms that the nanoparticles are ferroelectric in nature. Switching behavior of nanoparticle clusters were studied and showed evidence for inhomogeneous switching. The dimensionality of domains within nanoparticles was found to be fractal in nature, with a dimensionality constant of 1.4, on par with ferroelectric BFO thin-films under 100 nm in thickness. Ferromagnetic resonance studies indicate BFO nanoparticles only weakly affect the magnetic response of LSMO.

  14. Nanoscale Electromechanics of Ferroelectric and Biological Systems: A New Dimension in Scanning Probe Microscopy

    SciTech Connect

    Kalinin, Sergei V [ORNL; Rodriguez, Brian J [ORNL; Jesse, Stephen [ORNL; Karapetian, Edgar [ORNL; Mirman, B [Suffolk University, Boston; Eliseev, E. A. [National Academy of Science of Ukraine, Kiev, Ukraine; Morozovska, A. N. [National Academy of Science of Ukraine, Kiev, Ukraine

    2007-01-01

    Functionality of biological and inorganic systems ranging from nonvolatile computer memories and microelectromechanical systems to electromotor proteins and cellular membranes is ultimately based on the intricate coupling between electrical and mechanical phenomena. In the past decade, piezoresponse force microscopy (PFM) has been established as a powerful tool for nanoscale imaging, spectroscopy, and manipulation of ferroelectric and piezoelectric materials. Here, we give an overview of the fundamental image formation mechanism in PFM and summarize recent theoretical and technological advances. In particular, we show that the signal formation in PFM is complementary to that in the scanning tunneling microscopy (STM) and atomic force microscopy (AFM) techniques, and we discuss the implications. We also consider the prospect of extending PFM beyond ferroelectric characterization for quantitative probing of electromechanical behavior in molecular and biological systems and high-resolution probing of static and dynamic polarization switching processes in low-dimensional ferroelectric materials and heterostructures.

  15. Low temperature dependent ferroelectric resistive switching in epitaxial BiFeO3 films

    NASA Astrophysics Data System (ADS)

    Yan, F.; Xing, G. Z.; Li, L.

    2014-03-01

    The ferroelectric switchable diode induced resistive switching behavior at low temperature has been investigated in the epitaxial BiFeO3 (BFO) thin films. The switchable diode can be tuned using a higher voltage at low temperatures. The diode barrier is determined to be ˜0.55 eV at the interface between BFO and electrode. The resistive switchable barrier with respect to the ferroelectric domain switching has been systematically characterized at various low temperatures. The temperature dependent conduction and leakage mechanisms have also been identified. These results can advance our understanding of resistive switching based on ferroelectric switchable diode at low working temperatures and potentially extend the applications of memristor to a larger temperature scale.

  16. Dynamic Observation of Brain-Like Learning in a Ferroelectric Synapse Device

    NASA Astrophysics Data System (ADS)

    Nishitani, Yu; Kaneko, Yukihiro; Ueda, Michihito; Fujii, Eiji; Tsujimura, Ayumu

    2013-04-01

    A brain-like learning function was implemented in an electronic synapse device using a ferroelectric-gate field effect transistor (FeFET). The FeFET was a bottom-gate type FET with a ZnO channel and a ferroelectric Pb(Zr,Ti)O3 (PZT) gate insulator. The synaptic weight, which is represented by the channel conductance of the FeFET, is updated by applying a gate voltage through a change in the ferroelectric polarization in the PZT. A learning function based on the symmetric spike-timing dependent synaptic plasticity was implemented in the synapse device using the multilevel weight update by applying a pulse gate voltage. The dynamic weighting and learning behavior in the synapse device was observed as a change in the membrane potential in a spiking neuron circuit.

  17. Magnetism-Driven Ferroelectricity in Double Perovskite Y2NiMnO6.

    PubMed

    Su, J; Yang, Z Z; Lu, X M; Zhang, J T; Gu, L; Lu, C J; Li, Q C; Liu, J-M; Zhu, J S

    2015-06-24

    We report the discovery of multiferroic behavior in double perovskite Y2NiMnO6. X-ray diffraction shows that the material has a centrosymmetric crystal structure of space group P21/n with Ni(2+)/Mn(4+) ordering. This result is further confirmed by aberration-corrected scanning transmission electron microscopy combined with atomic resolution electron energy loss spectroscopy. The appearance of ferroelectric polarization coincides with the magnetic phase transition (?67 K), which indicates that the ferroelectricity is driven by magnetism, and this is further confirmed by its strong magnetoelectric (ME) effect. We proposed the origin of the ferroelectricity is associated with the combination of Ni(2+)/Mn(4+) charge ordering and the ???? spin ordering. When compared with other known magnetic multiferroics, Y2NiMnO6 displays several attractive multiferroic properties, including high polarization (?145 ?C/m(2)), a high multiferroic transition temperature (?67 K), and strong ME coupling (?21%). PMID:26017622

  18. Enhancing electrical energy storage density in anti-ferroelectric ceramics using ferroelastic domain switching

    NASA Astrophysics Data System (ADS)

    Patel, Satyanarayan; Chauhan, Aditya; Vaish, Rahul

    2014-12-01

    Capacitors form an indispensable part of many modern electrical and electronic devices. An ideal capacitor is expected to possess high power and energy density along with enhanced energy recovery characteristics. Anti-ferroelectric materials form a suitable candidate for ceramic-based capacitor applications, owing to their low loss and high energy density. However, these materials show ample room for improvement through physical means. In this regard, the present work deals with mechanical tuning of the energy storage density and recoverable efficiency in known anti-ferroelectric materials. For this study, various configurations of (Pb1?xLax)(Zr0.90Ti0.10)1?x/4O3 (PLZTx) ceramics have been investigated. Both mechanical confinement and temperature applications have been shown to improve the performance characteristics of all selected compositions. This behavior has been explained on the basis of competing ferroelectric and ferroelastic domain rotations. The application of suitable stress/temperature reduces hysteresis losses and delays anti-ferroelectric ? ferroelectric phase transformation, which increases the electrical energy storage capacity of these materials. Mechanical confinement was observed to provide an increase in energy storage density and efficiency by approximately 38% and 25%, respectively, for the PLZT4 composition. The highest recoverable energy density of 698 m J cm?3 was achieved under compressive stress of a 100 MPa and 60 kV cm?1 applied electric field.

  19. Ferroelectric order in highly disordered molecular-ionic crystals

    NASA Astrophysics Data System (ADS)

    Paja?, Zdzis?aw; Czarnecki, Piotr; Szafra?ska, Barbara; Ma?uszy?ska, Hanna; Fojud, Zbigniew

    2004-04-01

    The ordering of the anionic sublattice at the coexisting high orientational disorder of the cationic sublattice produces spontaneous polarization in imidazolium tetrafluoroborate [C3N2H5]+[BF4]-. This ferroelectric crystal exhibits the Curie point at 297.0 K and undergoes two other polymorphic phase transitions at 213.6 and 187.8 K. In spite of its pentagonal ring the dynamically disordered polar cation is localized at a special position on the threefold axis of the highly symmetrical rhombohedral unit cell. Thus it does not contribute immediately to the spontaneous polarization which originates predominantly from the behavior of the distorted tetrahedral fluoroborate anion.

  20. Characterization of a Common-Gate Amplifier Using Ferroelectric Transistors

    NASA Technical Reports Server (NTRS)

    Hunt, Mitchell; Sayyah, Rana; MacLeod, Todd C.; Ho, Fat D.

    2011-01-01

    In this paper, the empirical data collected through experiments performed using a FeFET in the common-gate amplifier circuit is presented. The FeFET common-gate amplifier was characterized by varying all parameters in the circuit, such as load resistance, biasing of the transistor, and input voltages. Due to the polarization of the ferroelectric layer, the particular behavior of the FeFET common-gate amplifier presents interesting results. Furthermore, the differences between a FeFET common-gate amplifier and a MOSFET common-gate amplifier are examined.

  1. Phase-field simulation of polarization switching and domain evolution in ferroelectric polycrystals

    E-print Network

    Chen, Long-Qing

    : Phase-field models; Ceramics; Ferroelectricity; Domain switching 1. Introduction Ferroelectric ceramicsPhase-field simulation of polarization switching and domain evolution in ferroelectric polycrystals under an applied elec- tric field in ferroelectric polycrystals. The model takes into account realistic

  2. Calligraphic Poling of Ferroelectric Material

    NASA Technical Reports Server (NTRS)

    Mohageg, Makan; Strekalov, Dmitry; Savchenkov, Anatoliy; Matsko, Adrey; Maleki, Lute; Iltchenko, Vladimir

    2007-01-01

    Calligraphic poling is a technique for generating an arbitrary, possibly complex pattern of localized reversal in the direction of permanent polarization in a wafer of LiNbO3 or other ferroelectric material. The technique is so named because it involves a writing process in which a sharp electrode tip is moved across a surface of the wafer to expose the wafer to a polarizing electric field in the desired pattern. The technique is implemented by use of an apparatus, denoted a calligraphic poling machine (CPM), that includes the electrode and other components as described in more detail below.

  3. Field-induced phase transition and relaxor character in submicrometer-structured lead-free (Bi0.5Na0.5)0.94Ba0.06TiO3 piezoceramics at the morphotropic phase boundary.

    PubMed

    Pardo, Lorena; Mercadelli, Elisa; García, Alvaro; Brebøl, Klaus; Galassi, Carmen

    2011-09-01

    Submicrometer-structured (Bi(0.5)Na(0.5))(0.94)Ba(0.06)TiO(3) ceramics ((G) < 720 nm) from nanopowders were studied. The real part of the optimum room temperature set of piezoelectric coefficients obtained from resonances of the BNBT6 dense ceramic disks and shear plates [d(31) = (-37 + 1.33i) pC·N(-1), d(15) = (158.3 - 8.31i) pC·N(-1), k(t) = 40.4%, k(p) = 26.8%, and k(15) = 40.2%] and d(33) (148 pC·N(-1)) can be compared with the reported properties for coarse-grained ceramics. Shear resonance of thickness-poled plates is observed at T = 140°C. Permittivity versus temperature curves of poled samples show relaxor character up to T(i) = 230°C on heating and T(i) = 210°C on cooling of the depoled samples. The phase transition from the room-temperature ferroelectric (FE) to a low-temperature non-polar at zero field (LTNPZF) phase can be observed as a sharp jump in ?(?)(33)'(T) curves or, as the degree of poling decreases, as a soft change of slope of the curves at T(FE-LTNPZF) = T(d) = 100°C. This dielectric anomaly is not observed on cooling of depoled samples, because the FE phase is field-induced. The observed macroscopic piezoelectric activity above T(d) is a consequence of the coexistence of nanoregions of the FE phase in the interval between T(FE-LTNPZF) and T(i). PMID:21937323

  4. New perspectives for ferroelectric LC-polymers

    SciTech Connect

    Brehmer, M.; Gebhard, E.; Wittig, T. [Univ. Mainz (Germany)

    1996-10-01

    LC-Elastomers prepared from ferroelectric LC-polymers are interesting materials for two reasons. From a materials point of view they are interesting because of their ferroelectric, piezoelectric and pyrroelectric properties. From a scientific point of view they are fascinating because they allow us to study the interplay of electric and mechanical forces in a rubbery material The coupling between the director reorientation and the network can be modified by crosslinking at the end of the mesogens or in the range of the polymer chains . In the last case the coupling is minimal. Besides the planar orientation in SSFLC-cells, free standing films offer the possibility of a homeotropic alignment of smectic liquid crystals ferroelectric LC elastomers of a different topology can be obtained by mixing a low molar mass or an oligomeric ferroelectric LC with a bifunctional crosslinkable: liquid crystal and performing photochemically a crosslinking reaction in one switching state of the smectic C* phase. As a result non crosslinkable ferroelectric LC will form micro-droplets surrounded by a densely crosslinked network, which is formed by the crosslinked non-ferroelectric liquid crystals. This gives a two phasic Volume or Network Stabilized Ferroelectric Liquid Crystal.

  5. Interplay of ferroelectricity and single electron tunneling

    NASA Astrophysics Data System (ADS)

    Fedorov, S. A.; Korolkov, A. E.; Chtchelkatchev, N. M.; Udalov, O. G.; Beloborodov, I. S.

    2014-04-01

    We investigate the interplay of ferroelectricity and quantum electron transport at the nanoscale in the regime of Coulomb blockade. Ferroelectric polarization in this case is no longer the external parameter but should be self-consistently calculated along with electron hopping probabilities leading to physical transport phenomena studied in this paper. These phenomena appear mostly due to effective screening of a grain electric field by ferroelectric environment rather than due to polarization dependent tunneling probabilities. At small bias voltages polarization can be switched by a single excess electron in the grain. In this case transport properties of a single electron transistor exhibit the instability (memory effect).

  6. Implementation of Ferroelectric Memories for Space Applications

    NASA Technical Reports Server (NTRS)

    Philpy, Stephen C.; Derbenwick, Gary F.; Kamp, David A.; Isaacson, Alan F.

    2000-01-01

    Ferroelectric random access semiconductor memories (FeRAMs) are an ideal nonvolatile solution for space applications. These memories have low power performance, high endurance and fast write times. By combining commercial ferroelectric memory technology with radiation hardened CMOS technology, nonvolatile semiconductor memories for space applications can be attained. Of the few radiation hardened semiconductor manufacturers, none have embraced the development of radiation hardened FeRAMs, due a limited commercial space market and funding limitations. Government funding may be necessary to assure the development of radiation hardened ferroelectric memories for space applications.

  7. Static Characteristics of the Ferroelectric Transistor Inverter

    NASA Technical Reports Server (NTRS)

    Mitchell, Cody; Laws, crystal; MacLeond, Todd C.; Ho, Fat D.

    2010-01-01

    The inverter is one of the most fundamental building blocks of digital logic, and it can be used as the foundation for understanding more complex logic gates and circuits. This paper presents the characteristics of an inverter circuit using a ferroelectric field-effect transistor. The voltage transfer characteristics are analyzed with respect to varying parameters such as supply voltage, input voltage, and load resistance. The effects of the ferroelectric layer between the gate and semiconductor are examined, and comparisons are made between the inverters using ferroelectric transistors and those using traditional MOSFETs.

  8. Ultrafast Photovoltaic Response in Ferroelectric Nanolayers

    SciTech Connect

    Daranciang, Dan

    2012-02-15

    We show that light drives large-amplitude structural changes in thin films of the prototypical ferroelectric PbTiO3 via direct coupling to its intrinsic photovoltaic response. Using time-resolved x-ray scattering to visualize atomic displacements on femtosecond timescales, photoinduced changes in the unit-cell tetragonality are observed. These are driven by the motion of photogenerated free charges within the ferroelectric and can be simply explained by a model including both shift and screening currents, associated with the displacement of electrons first antiparallel to and then parallel to the ferroelectric polarization direction.

  9. Effect of co-substitution of nitrogen and fluorine in BaTiO3 on ferroelectricity and other properties.

    PubMed

    Kumar, Nitesh; Pan, Jaysree; Aysha, N; Waghmare, Umesh V; Sundaresan, A; Rao, C N R

    2013-08-28

    BaTiO3, with both nitrogen and fluorine substituted for oxygen, has been prepared and the properties of the doped material with the composition BaTiO2:8N0:1F0:1 have been studied. The color of the sample changes to light green on doping, accompanying a broad visible absorption band with its edge at 2.5 eV. The first-order ferroelectric transition changes to a broad transition on doping along with a decrease in the dielectric constant. We have examined the local structure, electronic structure and polar lattice dynamical properties of N and F co-substituted BaTiO3 using first-principles density functional theory-based calculations and derived the mechanism of the diffuse ferroelectric transition observed here with a broad peak in the temperature-dependent dielectric response. The calculated Born charges clearly reveal a strong disparity in the interaction of N, O and F with Ti: N being the most ferro-active, with a highly anomalous charge, and F being the least active, with an almost nominal charge. This originates from an electronic structure in which the top-most valence band is constituted of the 2p states of N, while the electronic states of F lie deep in the energy band, resulting in a local structure with short covalent Ti–N and long ionic Ti–F bonds. Disorder in these hetero ferro-active anions leads to a relaxor-like diffuse phase transition and a reduction in polarization. Calculations confirm the reduction of 0.65 eV in the bandgap of BaTiO3, which changes from indirect to direct type. PMID:23912943

  10. Pure ferroelectric polarization of lead-free Na0.5K0.5NbO3 thin films by using the double wave method

    NASA Astrophysics Data System (ADS)

    Lee, Hai Joon; Ahn, Chang Won; Won, Sung Sik; Tange, Achiri; Park, Bong Chan; Seog, Hae Jin; Kim, Ill Won

    2015-05-01

    Na0.5K0.5NbO3 (NKN) thin films were grown on Pt(111)/Ti/SiO2/Si substrates by using RFmagnetron sputtering. We investigated the behavior of the ferroelectric polarization. Well-saturated P-V hysteresis loops were observed, but the P-V hysteresis loops were sometimes distorted and consisted of three roughly parallel components, such as ferroelectric, dielectric and conductive components. Correction methods were proposed to identify the undesirable components and the pure ferroelectric polarization components from the observed P-V hysteresis loops. A new polarization hysteresis loop measurement technique, the double wave method (DWM), was applied to NKN thin films to obtain pure ferroelectric polarization and elucidate the behaviors of the polarization components.

  11. Studies of Ferroelectric and Magnetic Phase Transitions in Pb1?xAxFe1\\/2Nb1\\/2O3 (ACa, Ba) Solid Solutions

    Microsoft Academic Search

    I. P. Raevski; S. P. Kubrin; S. I. Raevskaya; V. V. Titov; S. A. Prosandeev; D. A. Sarychev; M. A. Malitskaya; V. V. Stashenko; I. N. Zakharchenko

    2010-01-01

    Dielectric and Mossbauer studies of Pb1-xAxFe1\\/2Nb1\\/2O3 (A- Ba, Ca) ceramic compositions show that the Néel temperature in these solid solutions drops down at x ? 0.15–0.20. At the same threshold the polarization also loses its long-range order and compositions with x > 0.1 exhibit relaxor behavior. The data obtained suggests that there exists a Pb-mediated superexchange controlling the long-range antiferromagnetic

  12. Strong anisotropy of ferroelectricity in lead-free bismuth silicate.

    PubMed

    Seol, Daehee; Taniguchi, Hiroki; Hwang, Jae-Yeol; Itoh, Mitsuru; Shin, Hyunjung; Kim, Sung Wng; Kim, Yunseok

    2015-07-21

    Bismuth silicate (Bi2SiO5) was recently suggested as a potential silicate based lead-free ferroelectric material. Here, we show the existence of ferroelectricity and explore the strong anisotropy of local ferroelectricity using piezoresponse force microscopy (PFM). Domain structures are reconstructed using angle-resolved PFM. Furthermore, piezoresponse hysteresis loops and piezoelectric coefficients are spatially investigated at the nanoscale. The obtained results confirm the existence of ferroelectricity with strong c-axis polarization. These results could provide basic information on the anisotropic ferroelectricity in Bi2SiO5 and furthermore suggest its considerable potential for lead-free ferroelectric applications with silicon technologies. PMID:26084633

  13. Ferroelectric and ferromagnetic properties in BaTiO3 thin films on Si (100)

    NASA Astrophysics Data System (ADS)

    Singamaneni, Srinivasa Rao; Punugupati, Sandhyarani; Prater, John T.; Hunte, Frank; Narayan, Jagdish

    2014-09-01

    In this paper, we report on the epitaxial integration of room temperature lead-free ferroelectric BaTiO3 thin (˜1050 nm) films on Si (100) substrates by pulsed laser deposition technique through a domain matching epitaxy paradigm. We employed MgO and TiN as buffer layers to create BaTiO3/SrRuO3/MgO/TiN/Si (100) heterostructures. C-axis oriented and cube-on-cube epitaxial BaTiO3 is formed on Si (100) as evidenced by the in-plane and out-of-plane x-ray diffraction, and transmission electron microscopy. X-ray photoemission spectroscopic measurements show that Ti is in 4(+) state. Polarization hysteresis measurements together with Raman spectroscopy and temperature-dependent x-ray diffraction confirm the room temperature ferroelectric nature of BaTiO3. Furthermore, laser irradiation of BaTiO3 thin film is found to induce ferromagnetic-like behavior but affects adversely the ferroelectric characteristics. Laser irradiation induced ferromagnetic properties seem to originate from the creation of oxygen vacancies, whereas the pristine BaTiO3 shows diamagnetic behavior, as expected. This work has opened up the route for the integration of room temperature lead-free ferroelectric functional oxides on a silicon platform.

  14. Interface control of bulk ferroelectric polarization

    SciTech Connect

    Yu, P [University of California, Berkeley; Luo, Weidong [ORNL; Yi, D. [University of California, Berkeley; Zhang, J.-X. [University of California, Berkeley; Rossell, M.D. [Lawrence Berkeley National Laboratory (LBNL); Yang, C.-H. [Korea Advanced Institute of Science and Technology; You, L. [University of California, Berkeley; Singh-Bhalla, G. B. [University of California, Berkeley & LBNL; Yang, S.Y [University of California, Berkeley; He, Q [University of California, Berkeley; Ramasse, Q. M. [Lawrence Berkeley National Laboratory (LBNL); Erni, R. [Lawrence Berkeley National Laboratory (LBNL); Martin, L. W. [University of Illinois, Urbana-Champaign; Chu, Y. H. [University of California, Berkeley; Pantelides, Sokrates T [ORNL; Pennycook, Stephen J [ORNL; Ramesh, R. [University of California, Berkeley

    2012-01-01

    The control of material interfaces at the atomic level has led to no- vel interfacial properties and functionalities. In particular, the study of polar discontinuities at interfaces between complex oxides lies at the frontier of modern condensed matter research. Here we em- ploy a combination of experimental measurements and theoretical calculations to demonstrate the control of a bulk property, namely ferroelectric polarization, of a heteroepitaxial bilayer by precise atomic-scale interface engineering. More specifically, the control is achieved by exploiting the interfacial valence mismatch to influence the electrostatic potential step across the interface, which manifests itself as the biased-voltage in ferroelectric hysteresis loops and determines the ferroelectric state. A broad study of diverse systems comprising different ferroelectrics and conducting perovskite un- derlayers extends the generality of this phenomenon.

  15. Negative capacitance in a ferroelectric capacitor.

    PubMed

    Khan, Asif Islam; Chatterjee, Korok; Wang, Brian; Drapcho, Steven; You, Long; Serrao, Claudy; Bakaul, Saidur Rahman; Ramesh, Ramamoorthy; Salahuddin, Sayeef

    2015-02-01

    The Boltzmann distribution of electrons poses a fundamental barrier to lowering energy dissipation in conventional electronics, often termed as Boltzmann Tyranny. Negative capacitance in ferroelectric materials, which stems from the stored energy of a phase transition, could provide a solution, but a direct measurement of negative capacitance has so far been elusive. Here, we report the observation of negative capacitance in a thin, epitaxial ferroelectric film. When a voltage pulse is applied, the voltage across the ferroelectric capacitor is found to be decreasing with time--in exactly the opposite direction to which voltage for a regular capacitor should change. Analysis of this 'inductance'-like behaviour from a capacitor presents an unprecedented insight into the intrinsic energy profile of the ferroelectric material and could pave the way for completely new applications. PMID:25502099

  16. Thermally tunable ferroelectric thin film photonic crystals.

    SciTech Connect

    Lin, P. T.; Wessels, B. W.; Imre, A.; Ocola, L. E.; Northwestern Univ.

    2008-01-01

    Thermally tunable PhCs are fabricated from ferroelectric thin films. Photonic band structure and temperature dependent diffraction are calculated by FDTD. 50% intensity modulation is demonstrated experimentally. This device has potential in active ultra-compact optical circuits.

  17. Ferroelectricity in yttrium-doped hafnium oxide

    NASA Astrophysics Data System (ADS)

    Müller, J.; Schröder, U.; Böscke, T. S.; Müller, I.; Böttger, U.; Wilde, L.; Sundqvist, J.; Lemberger, M.; Kücher, P.; Mikolajick, T.; Frey, L.

    2011-12-01

    Structural and electrical evidence for a ferroelectric phase in yttrium doped hafnium oxide thin films is presented. A doping series ranging from 2.3 to 12.3 mol% YO1.5 in HfO2 was deposited by a thermal atomic layer deposition process. Grazing incidence X-ray diffraction of the 10 nm thick films revealed an orthorhombic phase close to the stability region of the cubic phase. The potential ferroelectricity of this orthorhombic phase was confirmed by polarization hysteresis measurements on titanium nitride based metal-insulator-metal capacitors. For 5.2 mol% YO1.5 admixture the remanent polarization peaked at 24 ?C/cm2 with a coercive field of about 1.2 MV/cm. Considering the availability of conformal deposition processes and CMOS-compatibility, ferroelectric Y:HfO2 implies high scaling potential for future, ferroelectric memories.

  18. Control of leakage conduction of high-fatigue-endurance (Pb, La)(Zr, Ti)O3 film ferroelectric capacitors with Pt\\/SrRuO3 electrodes

    Microsoft Academic Search

    I. Stolichnov; A. Tagantsev; N. Setter; J. S. Cross; M. Tsukada

    1999-01-01

    Leakage conduction of (Pb, La)(Zr, Ti)O3 (PLZT) films grown on Pt bottom electrode, with Pt and Pt\\/SrRuO3 (Pt\\/SRO) top electrodes is studied. It is found that the conduction behavior of the ferroelectric capacitors strongly varies depending on the degree of interdiffusion from the electrode into the ferroelectric material. If the diffusion is limited, the conduction properties of the Pt\\/SRO\\/PLZT\\/Pt capacitor

  19. Ferroelectric-ferromagnetic multilayers: A magnetoelectric heterostructure with high output charge signal

    SciTech Connect

    Prokhorenko, S. [Laboratoire Structures, Propriétés et Modélisation des Solides, UMR CNRS—École Centrale Paris, 92295 Châtenay-Malabry (France); Kohlstedt, H. [Nanoelektronik, Technische Fakultät, Christian-Albrechts-Universität zu Kiel, D-24143 Kiel (Germany); Pertsev, N. A., E-mail: pertsev.domain@mail.ioffe.ru [A. F. Ioffe Physical-Technical Institute and St. Petersburg State Polytechnical University, St. Petersburg, 194021 and 195251 (Russian Federation)

    2014-09-21

    Multiferroic composites and heterostructures comprising ferroelectric and ferromagnetic materials exhibit room-temperature magnetoelectric (ME) effects greatly exceeding those of single-phase magnetoelectrics known to date. Since these effects are mediated by the interfacial coupling between ferroic constituents, the ME responses may be enhanced by increasing the density of interfaces and improving their quality. A promising material system providing these features is a ferroelectric-ferromagnetic multilayer with epitaxial interfaces. In this paper, we describe theoretically the strain-mediated direct ME effect exhibited by free-standing multilayers composed of single-crystalline ferroelectric nanolayers interleaved by conducting ferromagnetic slabs. Using a nonlinear thermodynamic approach allowing for specific mechanical boundary conditions of the problem, we first calculate the polarization states and dielectric properties of ferroelectric nanolayers in dependence on the lattice mismatch between ferroic constituents and their volume fractions. In these calculations, the ferromagnetic component is described by a model which combines linear elastic behavior with magnetic-field-dependent lattice parameters. Then the quasistatic ME polarization and voltage coefficients are evaluated using the theoretical strain sensitivity of ferroelectric polarization and measured effective piezomagnetic coefficients of ferromagnets. For Pb(Zr?.?Ti?.?)O?-FeGaB and BaTiO?-FeGaB multilayers, the ME coefficients are calculated numerically as a function of the FeGaB volume fraction and used to evaluate the output charge and voltage signals. It is shown that the multilayer geometry of a ferroelectric-ferromagnetic nanocomposite opens the way for a drastic enhancement of the output charge signal. This feature makes biferroic multilayers advantageous for the development of ultrasensitive magnetic-field sensors for technical and biomedical applications.

  20. Ferroelectric-ferromagnetic multilayers: A magnetoelectric heterostructure with high output charge signal

    NASA Astrophysics Data System (ADS)

    Prokhorenko, S.; Kohlstedt, H.; Pertsev, N. A.

    2014-09-01

    Multiferroic composites and heterostructures comprising ferroelectric and ferromagnetic materials exhibit room-temperature magnetoelectric (ME) effects greatly exceeding those of single-phase magnetoelectrics known to date. Since these effects are mediated by the interfacial coupling between ferroic constituents, the ME responses may be enhanced by increasing the density of interfaces and improving their quality. A promising material system providing these features is a ferroelectric-ferromagnetic multilayer with epitaxial interfaces. In this paper, we describe theoretically the strain-mediated direct ME effect exhibited by free-standing multilayers composed of single-crystalline ferroelectric nanolayers interleaved by conducting ferromagnetic slabs. Using a nonlinear thermodynamic approach allowing for specific mechanical boundary conditions of the problem, we first calculate the polarization states and dielectric properties of ferroelectric nanolayers in dependence on the lattice mismatch between ferroic constituents and their volume fractions. In these calculations, the ferromagnetic component is described by a model which combines linear elastic behavior with magnetic-field-dependent lattice parameters. Then the quasistatic ME polarization and voltage coefficients are evaluated using the theoretical strain sensitivity of ferroelectric polarization and measured effective piezomagnetic coefficients of ferromagnets. For Pb(Zr0.5Ti0.5)O3-FeGaB and BaTiO3-FeGaB multilayers, the ME coefficients are calculated numerically as a function of the FeGaB volume fraction and used to evaluate the output charge and voltage signals. It is shown that the multilayer geometry of a ferroelectric-ferromagnetic nanocomposite opens the way for a drastic enhancement of the output charge signal. This feature makes biferroic multilayers advantageous for the development of ultrasensitive magnetic-field sensors for technical and biomedical applications.

  1. An epitaxial ferroelectric tunnel junction on silicon.

    PubMed

    Li, Zhipeng; Guo, Xiao; Lu, Hui-Bin; Zhang, Zaoli; Song, Dongsheng; Cheng, Shaobo; Bosman, Michel; Zhu, Jing; Dong, Zhili; Zhu, Weiguang

    2014-11-12

    Epitaxially grown functional perovskites on silicon (001) and the ferroelectricity of a 3.2 nm thick BaTiO3 barrier layer are demonstrated. The polarization-switching-induced change in tunneling resistance is measured to be two orders of magnitude. The obtained results suggest the possibility of integrating ferroelectric tunnel junctions as binary data storage media in non-volatile memory cells on a silicon platform. PMID:25200550

  2. Microelectromechanical systems based on ferroelectric thin films

    Microsoft Academic Search

    Dennis L. Polla

    1995-01-01

    Ferroelectric thin films have been integrated in silicon-based microelectromechanical systems, commonly called MEMS. Several thin films of the PZT family have been used in the formation of both microsensors and microactuators in processes compatible with 2-?m analog CMOS technology. Ferroelectric MEMS offer significant advantages of high signal-to-noise, low power dissipation, and high force generation in comparison to other MEMS technologies

  3. Interaction of Terahertz Radiation with Ferroelectrics

    Microsoft Academic Search

    Keith Nelson

    2007-01-01

    Ferroelectric crystals have long been used as acoustic transducers and receivers. An extensive toolset has been developed for MHz-frequency acoustic wave generation, control, guidance, and readout. In recent years, an analogous toolset has been developed for terahertz wave transduction and detection. Femtosecond optical pulses irradiate ferroelectric crystals to generate responses in the 0.1-5 THz frequency range that are admixtures of

  4. Dielectric constant tunability at microwave frequencies and pyroelectric behavior of lead-free submicrometer-structured (Bi0.5Na0.5)1-xBaxTiO3 ferroelectric ceramics.

    PubMed

    Martínez, Félix L; Hinojosa, Juan; Doménech, Ginés; Fernández-Luque, Francisco J; Zapata, Juan; Ruiz, Ramon; Pardo, Lorena

    2013-08-01

    In this article, we show that the dielectric constant of lead-free ferroelectric ceramics based on the solid solution (1-x)(Bi(0.5)Na(0.5))TiO(3)-xBaTiO(3), with compositions at or near the morphotropic phase boundary (MPB), can be tuned by a local applied electric field. Two compositions have been studied, one at the MPB, with x = 0.06 (BNBT6), and another one nearer the BNT side of the phase diagram, with x = 0.04 (BNBT4). The tunability of the dielectric constant is measured at microwave frequencies between 100 MHz and 3 GHz by a nonresonant method and simultaneously applying a dc electric field. As expected, the tunability is higher for the composition at the MPB (BNBT6), reaching a maximum value of 60% for an electric field of 900 V/cm, compared with the composition below this boundary (BNBT4), which saturates at 40% for an electric field of 640 V/cm. The high tunability in both cases is attributed to the fine grain and high density of the samples, which have a submicrometer homogeneous grain structure with grain size of the order of a few hundred nanometers. Such properties make these ceramics attractive for microwave tunable devices. Finally, we have tested these ceramics for their application as infrared pyroelectric detectors and we have found that the pyroelectric figure of merit is comparable to traditional lead-containing pyroelectrics. PMID:25004530

  5. Fast Switching Ferroelectric Materials for Accelerator Applications

    SciTech Connect

    Kanareykin, A.; Schoessow, P. [Euclid Techlabs LLC, Solon, OH 44139 (United States); Nenasheva, E. [Ceramics Co. Ltd, St.Petersburg 194223 (Russian Federation); Yakovlev, V. [Omega-P Inc., New Haven, CT 06511 (United States); Dedyk, A.; Karmanenko, S.; Kozyrev, A.; Osadchy, V.; Kosmin, D.; Semenov, A. [St. Petersburg Electrical Engineering University, St. Petersburg 197376 (Russian Federation)

    2006-11-27

    Fast switching (<10 nsec) measurement results on the recently developed BST(M) (barium strontium titanium oxide composition with magnesium-based additions) ferroelectric materials are presented. These materials can be used as the basis for new advanced technology components suitable for high-gradient accelerators. A ferroelectric ceramic has an electric field-dependent dielectric permittivity that can be altered by applying a bias voltage. Ferroelectric materials offer significant benefits for linear collider applications, in particular, for switching and control elements where a very short response time of <10 nsec is required. The measurement results presented here show that the new BST(M) ceramic exhibits a high tunability factor: a bias field of 40-50 kV/cm reduces the permittivity by a factor of 1.3-1.5. The recently developed technology of gold biasing contact deposition on large diameter (110 cm) thin wall ferroelectric rings allowed {approx}few nsec switching times in witness sample experiments. The ferroelectric rings can be used at high pulsed power (tens of megawatts) for X-band components as well as at high average power in the range of a few kilowatts for the L-band phase-shifter, under development for optimization of the ILC rf coupling. Accelerator applications include fast active X-band and Ka-band high-power ferroelectric switches, high-power X-band and L-band phase shifters, and tunable dielectric-loaded accelerating structures.

  6. Deaging and Asymmetric Energy Landscapes in Electrically Biased Ferroelectrics

    SciTech Connect

    Tutuncu, Goknur; Damjanovic, Dragan; Chen, Jun; Jones, Jacob L. (EPFL); (UST - China); (Florida)

    2012-09-05

    In ferroic materials, the dielectric, piezoelectric, magnetic, and elastic coefficients are significantly affected by the motion of domain walls. This motion can be described as the propagation of a wall across various types and strengths of pinning centers that collectively constitute a force profile or energetic landscape. Biased domain structures and asymmetric energy landscapes can be created through application of high fields (such as during electrical poling), and the material behavior in such states is often highly asymmetric. In some cases, this behavior can be considered as the electric analogue to the Bauschinger effect. The present Letter uses time-resolved, high-energy x-ray Bragg scattering to probe this asymmetry and the associated deaging effect in the ferroelectric morphotropic phase boundary composition 0.36BiScO{sub 3}-0.64PbTiO{sub 3}.

  7. Electroactive fluorinate-based polymers: Ferroelectric and dielectric properties

    NASA Astrophysics Data System (ADS)

    Yu, Zhi; Ang, Chen

    2004-12-01

    The dielectric, ferroelectric, and electroactive strain behavior of poly(vinylidene fluoride-trifluoroethylene) copolymers and poly(vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene) terpolymers is studied in a wide temperature and frequency range. The dielectric response from two dielectric polarization processes, modes A(A') and B, and the dielectric-background contribution can be identified for these polymers by using the Cole-Cole plot method. Therefore physically reasonable parameters are obtained by fitting the relaxation time to the Vogel-Fulcher relation. On the other hand, the dielectric relaxation step and high strain decrease simultaneously with decreasing temperature; this indicates that the dielectric relaxation process and high strain behavior are strongly correlated. The electron-irradiation effect in copolymers and the monomer effect in terpolymers are discussed.

  8. Two Components of the Macroscopic Polarization in Pb(Mg1/3Nb2/3)O3 Relaxor Ferroelectric

    NASA Astrophysics Data System (ADS)

    Deguchi, Kiyoshi

    2015-07-01

    A pyroelectric charge measurement was carried out for Pb(Mg1/3Nb2/3)O3 over the wide temperature range from 80 to 475 K. Macroscopic polarization was observed up to 420 ± 30 K, with marked changes at approximately 200 and 420 K. The first component of a polarization developing below 200 K is about 20 µC/cm2, and the second component developing below 420 K is about 4 µC/cm2. These components can be observed together or selectively depending on field cooling conditions, indicating that these components have respective origins that are different from each other. The results provide direct evidence of the occurrence of the static polar nanoregion below around 420 K.

  9. Application of a Ferroelectric Material in an Energy Conversion Device

    Microsoft Academic Search

    J. D. Childress

    1962-01-01

    The thermodielectric converter, a device employing a ferroelectric material as the active element in converting thermal to electrical energy, is analyzed. The efficiency and power-handling capacity are calculated for operation of a ferroelectric material in the induced-ferroelectric region on the basis of an idealization of the polarization (P-E) characteristics. The idealization includes the induced-ferroelectric transition but excludes hysteresis and other

  10. Abnormal electric-field-induced light scattering in Pb(Mg1/3Nb2/3)O3-PbTiO3 transparent ceramics

    NASA Astrophysics Data System (ADS)

    Zhou, Yibo; Zhao, Wei; Ruan, Wei; Zeng, Jiangtao; Zheng, Liaoying; Cheng, Jian; Li, Guorong

    2015-03-01

    We present a strong electric-field-induced light scattering phenomenon in relaxor ferroelectrics 75Pb(Mg1/3Nb2/3)-25PbTiO3 transparent ceramics under a weak threshold electric field, which is attributed to the abrupt growth of polar nanoregions above the threshold field with a significant change of local crystal symmetry, dielectric, and Raman response. These results provide further understanding on the electric field-induced domain behaviors and peculiar properties in relaxor ferroelectrics.

  11. Piezoelectricity and ferroelectricity of cellular polypropylene electrets films characterized by piezoresponse force microscopy

    NASA Astrophysics Data System (ADS)

    Miao, Hongchen; Sun, Yao; Zhou, Xilong; Li, Yingwei; Li, Faxin

    2014-08-01

    Cellular electrets polymer is a new ferroelectret material exhibiting large piezoelectricity and has attracted considerable attentions in researches and industries. Property characterization is very important for this material and current investigations are mostly on macroscopic properties. In this work, we conduct nanoscale piezoelectric and ferroelectric characterizations of cellular polypropylene (PP) films using piezoresponse force microscopy (PFM). First, both the single-frequency PFM and dual-frequency resonance-tracking PFM testings were conducted on the cellular PP film. The localized piezoelectric constant d33 is estimated to be 7-11pC/N by correcting the resonance magnification with quality factor and it is about one order lower than the macroscopic value. Next, using the switching spectroscopy PFM (SS-PFM), we studied polarization switching behavior of the cellular PP films. Results show that it exhibits the typical ferroelectric-like phase hysteresis loops and butterfly-shaped amplitude loops, which is similar to that of a poly(vinylidene fluoride) (PVDF) ferroelectric polymer film. However, both the phase and amplitude loops of the PP film are intensively asymmetric, which is thought to be caused by the nonzero remnant polarization after poling. Then, the D-E hysteresis loops of both the cellular PP film and PVDF film were measured by using the same wave form as that used in the SS-PFM, and the results show significant differences. Finally, we suggest that the ferroelectric-like behavior of cellular electrets films should be distinguished from that of typical ferroelectrics, both macroscopically and microscopically.

  12. Piezoelectricity and ferroelectricity of cellular polypropylene electrets films characterized by piezoresponse force microscopy

    SciTech Connect

    Miao, Hongchen; Sun, Yao; Zhou, Xilong; Li, Yingwei [LTCS and Department of Mechanics and Engineering Science, College of Engineering, Peking University, Beijing 100871 (China); Li, Faxin, E-mail: lifaxin@pku.edu.cn [LTCS and Department of Mechanics and Engineering Science, College of Engineering, Peking University, Beijing 100871 (China); HEDPS and Center for Applied Physics and Technology, Peking University, Beijing (China)

    2014-08-14

    Cellular electrets polymer is a new ferroelectret material exhibiting large piezoelectricity and has attracted considerable attentions in researches and industries. Property characterization is very important for this material and current investigations are mostly on macroscopic properties. In this work, we conduct nanoscale piezoelectric and ferroelectric characterizations of cellular polypropylene (PP) films using piezoresponse force microscopy (PFM). First, both the single-frequency PFM and dual-frequency resonance-tracking PFM testings were conducted on the cellular PP film. The localized piezoelectric constant d{sub 33} is estimated to be 7–11pC/N by correcting the resonance magnification with quality factor and it is about one order lower than the macroscopic value. Next, using the switching spectroscopy PFM (SS-PFM), we studied polarization switching behavior of the cellular PP films. Results show that it exhibits the typical ferroelectric-like phase hysteresis loops and butterfly-shaped amplitude loops, which is similar to that of a poly(vinylidene fluoride) (PVDF) ferroelectric polymer film. However, both the phase and amplitude loops of the PP film are intensively asymmetric, which is thought to be caused by the nonzero remnant polarization after poling. Then, the D-E hysteresis loops of both the cellular PP film and PVDF film were measured by using the same wave form as that used in the SS-PFM, and the results show significant differences. Finally, we suggest that the ferroelectric-like behavior of cellular electrets films should be distinguished from that of typical ferroelectrics, both macroscopically and microscopically.

  13. Processing and Properties of Strontium Bismuth Vanadate Niobate Ferroelectric Ceramics

    E-print Network

    Cao, Guozhong

    Processing and Properties of Strontium Bismuth Vanadate Niobate Ferroelectric Ceramics Yun Wu, Chau condition, microstructure, and dielectric properties of SBVN ferroelectric ceramics are discussed. I properties of SBN ferroelectric ceramics. It was found that doping with La3 and Ca2 resulted

  14. Dramatically enhanced effective electrostriction in ferroelectric polymeric composites

    E-print Network

    Li, Jiangyu

    , and electromechanical coupling factor, where high-dielectric-constant ceramics are arranged in series with ferroelectricDramatically enhanced effective electrostriction in ferroelectric polymeric composites JiangYu Lia-0526 Received 2 May 2002; accepted for publication 17 July 2002 This letter reports a ferroelectric polymeric

  15. Ferroelectric cathodes in transverse magnetic fields A. Dunaevsky,a)

    E-print Network

    and patterned front electrodes, which cover ferroelectric ceramics, results in electron emis- sion from the side; the thickness and the composition of the ferroelectric ceramics; and the amplitude, the duration, and the timeFerroelectric cathodes in transverse magnetic fields A. Dunaevsky,a) Y. Raitses, and N. J. Fisch

  16. FERROELECTRIC PLASMA SOURCE FOR HEAVY ION BEAM CHARGE NEUTRALIZATION *

    E-print Network

    Gilson, Erik

    be suitable. To produce one-meter plasma, large-volume plasma sources based upon ferroelectric ceramics and operate at low neutral pressures. The source utilizes the ferroelectric ceramic BaTiO3 to form metal of the ceramic by placing a wire grid on the front surface. A prototype ferroelectric source 20 cm long has

  17. Critical thickness for ferroelectricity in perovskite ultrathin films

    Microsoft Academic Search

    Javier Junquera; Philippe Ghosez

    2003-01-01

    The integration of ferroelectric oxide films into microelectronic devices, combined with the size reduction constraints imposed by the semiconductor industry, have revived interest in the old question concerning the possible existence of a critical thickness for ferroelectricity. Current experimental techniques have allowed the detection of ferroelectricity in perovskite films down to a thickness of 40Å (ten unit cells), ref. 3.

  18. Dual tunable thin-film ferrite-ferroelectric slotline resonator

    E-print Network

    Srinivasan, Gopalan

    Dual tunable thin-film ferrite-ferroelectric slotline resonator A.A. Semenov, P.Yu. Beljavski, A garnet and ferroelectric barium strontium titanate films in a slotline structure is proposed ferrite and ferroelectric layered structure, therefore, pro- vides the advantages associated with both

  19. CuInP2S6 Room Temperature Layered Ferroelectric.

    PubMed

    Belianinov, A; He, Q; Dziaugys, A; Maksymovych, P; Eliseev, E; Borisevich, A; Morozovska, A; Banys, J; Vysochanskii, Y; Kalinin, S V

    2015-06-10

    We explore ferroelectric properties of cleaved 2-D flakes of copper indium thiophosphate, CuInP2S6 (CITP), and probe size effects along with limits of ferroelectric phase stability, by ambient and ultra high vacuum scanning probe microscopy. CITP belongs to the only material family known to display ferroelectric polarization in a van der Waals, layered crystal at room temperature and above. Our measurements directly reveal stable, ferroelectric polarization as evidenced by domain structures, switchable polarization, and hysteresis loops. We found that at room temperature the domain structure of flakes thicker than 100 nm is similar to the cleaved bulk surfaces, whereas below 50 nm polarization disappears. We ascribe this behavior to a well-known instability of polarization due to depolarization field. Furthermore, polarization switching at high bias is also associated with ionic mobility, as evidenced both by macroscopic measurements and by formation of surface damage under the tip at a bias of 4 V-likely due to copper reduction. Mobile Cu ions may therefore also contribute to internal screening mechanisms. The existence of stable polarization in a van-der-Waals crystal naturally points toward new strategies for ultimate scaling of polar materials, quasi-2D, and single-layer materials with advanced and nonlinear dielectric properties that are presently not found in any members of the growing "graphene family". PMID:25932503

  20. Enhanced charge separation in organic photovoltaic films doped with ferroelectric dipoles

    SciTech Connect

    Nalwa, Kanwar; Carr, John; Mahadevapuram, Rakesh; Kodali, Hari; Bose, Sayantan; Chen, Yuqing; Petrich, Jacob; Ganapathysubramanian, Baskar; Chaudhary, Sumit

    2012-02-23

    A key requirement for realizing efficient organic photovoltaic (OPV) cells is the dissociation of photogenerated electron-hole pairs (singlet-excitons) in the donor polymer, and charge-transfer-excitons at the donor–acceptor interface. However, in modern OPVs, these excitons are typically not sufficiently harnessed due to their high binding energy. Here, we show that doping the OPV active-layers with a ferroelectric polymer leads to localized enhancements of electric field, which in turn leads to more efficient dissociation of singlet-excitons and charge-transfer-excitons. Bulk-heterojunction OPVs based on poly(3-hexylthiophene):[6,6]-phenyl-C61-butyric acid methyl ester are fabricated. Upon incorporating a ferroelectric polymer as additive in the active-layer, power conversion efficiencies increase by nearly 50%, and internal quantum efficiencies approach 100% – indicating complete exciton dissociation at certain photon energies. Similar enhancements in bilayer-heterojunctions, and direct influence of ferroelectric poling on device behavior show that improved dissociation is due to ferroelectric dipoles rather than any morphological change. Enhanced singlet-exciton dissociation is also revealed by photoluminescence lifetime measurements, and predicted by simulations using a numerical device model.

  1. Electrical properties of NaSr2Nb5O15 ferroelectric ceramic

    NASA Astrophysics Data System (ADS)

    Behera, Banarji; Pradhan, Nihar; Nayak, P.

    2012-02-01

    Since the discovery of ferroelectricity, tungsten bronze (TB) ferroelectrics has been a rapid progress in search of new TB-type materials for applications such as capacitors, actuators, transducers, ferroelectric random access memory and display technologies. The materials with TB structure have potential advantages for devices because of their high dielectric constant and low tangent loss. In view of the above importance we have studied the electrical properties of NaSr2Nb5O15 (NSN) ferroelectric ceramic. The polycrystalline NaSr2Nb5O15 (NSN) was prepared by mixed oxide method at high temperature. Electrical properties of NSN have been studied using complex impedance spectroscopy (CIS) with wide range of frequency (10^2-10^6 Hz) and temperature. The complex impedance plot reveals the main contribution of bulk effect. The bulk resistance has been decreased with rise in temperature. The negative temperature coefficient of resistance (NTCR) manifests a semiconductor like behavior. The ac conductivity spectrum was found to obey Jonscher's universal power law.

  2. Ferroelectric switching in Bi4Ti3O12 nanorods.

    PubMed

    Azodi, Mehrnoosh; Harnagea, Catalin; Buscaglia, Vincenzo; Buscaglia, Maria Theresa; Nanni, Paolo; Rosei, Federico; Pignolet, Alain

    2012-09-01

    We report the piezoelectric and ferroelectric properties of individual one-dimensional objects made of Bi(4)Ti(3)O(12) (BiT). The nanorods and nanowires investigated in this study were fabricated by a two-step process: 1) preparation of reactive templates using hydrothermal-like synthesis and colloidal chemistry and 2) transformation of the reactive templates in Bi(4)Ti(3)O(12) by solid-state reaction, overcoming the morphological instability problem of 1-D templates. Using piezoresponse force microscopy (PFM) with both out-of-plane and in-plane detection capability, we show that both types of objects exhibit strong piezoelectric activity and good switching ferroelectric behavior. Analysis of the PFM hysteresis loops obtained revealed that the coercive voltage of the in-plane PFM signal can be either equal to or different from that of the out-of-plane response. We associate these situations with two types of polarization switching mechanisms: direct 180° switching, and via rotation of polarization, resulting from the independent switching of the components along the a- and ccrystallographic axes. In a few instances, we observe a negative piezoelectric coefficient, which we explain by the specific shape of the piezoelectric surface of Bi(4)Ti(3)O(12). PMID:23007759

  3. Spatially resolved probing of Preisach density in polycrystalline ferroelectric thin films

    SciTech Connect

    Guo, Senli [ORNL; Ovchinnikov, Oleg S [ORNL; Curtis, Mark E [University of Oklahoma, Norman; Johnson, Matthew B [University of Oklahoma, Norman; Jesse, Stephen [ORNL; Kalinin, Sergei V [ORNL

    2010-01-01

    Applications of the ferroelectric materials for the information storage necessitate the understanding of local switching behavior on the level of individual grains and microstructural elements. In particular, implementation of multilevel neuromorphic elements requires the understanding of history-dependent polarization responses. Here, we introduce the spatially resolved approach for mapping local Preisach densities in polycrystalline ferroelectrics based on first-order reversal curve (FORC) measurements over spatially resolved grid by piezoresponse force spectroscopy using tip-electrode. The band excitation approach allowed effective use of cantilever resonances to amplify weak piezoelectric signal and also provided insight in position-, voltage-, and voltage history-dependent mechanical properties of the tip-surface contact. Several approaches for visualization and comparison of the multidimensional data sets formed by FORC families or Preisach densities at each point are introduced and compared. The relationship between switching behavior and microstructure is analyzed.

  4. Enhanced energy harvesting in commercial ferroelectric materials

    NASA Astrophysics Data System (ADS)

    Patel, Satyanarayan; Chauhan, Aditya; Vaish, Rahul

    2014-04-01

    Ferroelectric materials are used in a number of applications ranging from simple sensors and actuators to ferroelectric random access memories (FRAMs), transducers, health monitoring system and microelectronics. The multiphysical coupling ability possessed by these materials has been established to be useful for energy harvesting applications. However, conventional energy harvesting techniques employing ferroelectric materials possess low energy density. This has prevented the successful commercialization of ferroelectric based energy harvesting systems. In this context, the present study aims at proposing a novel approach for enhanced energy harvesting using commercially available ferroelectric materials. This technique was simulated to be used for two commercially available piezoelectric materials namely PKI-552 and APCI-840, soft and hard lead-zirconate-titanate (PZT) pervoskite ceramics, respectively. It was observed that a maximum energy density of 348 kJm-3cycle-1 can be obtained for cycle parameters of (0-1 ton compressive stress and 1-25 kV.cm-1 electric field) using APCI-840. The reported energy density is several hundred times larger than the maximum energy density reported in the literature for vibration harvesting systems.

  5. Ferroelectric Field Effect Transistor Model Using Partitioned Ferroelectric Layer and Partial Polarization

    NASA Technical Reports Server (NTRS)

    MacLeod, Todd C.; Ho, Fat D.

    2004-01-01

    A model of an n-channel ferroelectric field effect transistor has been developed based on both theoretical and empirical data. The model is based on an existing model that incorporates partitioning of the ferroelectric layer to calculate the polarization within the ferroelectric material. The model incorporates several new aspects that are useful to the user. It takes into account the effect of a non-saturating gate voltage only partially polarizing the ferroelectric material based on the existing remnant polarization. The model also incorporates the decay of the remnant polarization based on the time history of the FFET. A gate pulse of a specific voltage; will not put the ferroelectric material into a single amount of polarization for that voltage, but instead vary with previous state of the material and the time since the last change to the gate voltage. The model also utilizes data from FFETs made from different types of ferroelectric materials to allow the user just to input the material being used and not recreate the entire model. The model also allows the user to input the quality of the ferroelectric material being used. The ferroelectric material quality can go from a theoretical perfect material with little loss and no decay to a less than perfect material with remnant losses and decay. This model is designed to be used by people who need to predict the external characteristics of a FFET before the time and expense of design and fabrication. It also allows the parametric evaluation of quality of the ferroelectric film on the overall performance of the transistor.

  6. Anomaly of Acoustic Phonon Mode in Ferroelectric Phase Transition of SrTiO3

    Microsoft Academic Search

    M. Takesada; M. Itoh; A. Onodera; T. Yagi

    2006-01-01

    The low frequency phonon mode in SrTiO3 has been investigated by highresolution technique, in order to clarify the relationship between the perfect softening of the ferroelectric Eu mode and the acoustic anomaly in the c44 mode reported previously near the phase transition point Tc. The drastic softening and the anomalous increase of intensity were reported as the anomalous behavior of

  7. Enhancement of the electromechanical response in ferroelectric ceramics by design

    E-print Network

    Jayachandran, K P; Rodrigues, H C; 10.1063/1.3089216

    2010-01-01

    It is demonstrated based on continuum mechanics modeling and simulation that it is possible to obtain polycrystalline ceramic ferroelectric materials which beggars single crystals in electromechanical properties. The local inhomogeneities at the ferroelectric domain-scale level due to spontaneous polarization and the underlying anisotropy are taken into consideration in the framework of mathematical homogenization of physical properties in ferroelectric materials. The intrinsic randomness of the spatial distribution of polarization is shown to be judiciously employed for the design of better polycrystalline ferroelectrics. The noncollinear rotation of the net polarization-vectors embedded in crystallites of the ceramic ferroelectrics is demonstrated to play the key role in the enhancement of physical properties.

  8. Piezoelectric and ferroelectric properties of lead-free LiNbO3-modified 0.97(Bi0.5Na0.5TiO3)-0.03BaZrO3 ceramics

    NASA Astrophysics Data System (ADS)

    Rahman, Jamil Ur; Hussain, Ali; Maqbool, Adnan; Malik, Rizwan Ahmed; Song, Tae Kwon; Kim, Myong Ho; Lee, Soonil; Kim, Won Jeong

    2015-02-01

    Lead-free piezoelectric ceramics (1- x) [(0.97Bi0.5Na0.5TiO3)]-0.03BaZrO3- xLiNbO3 (BNT-BZ3- xLN) with x = (0-0.07) were synthesized using the conventional solid-state reaction method, and their crystal structure, microstructure, and dielectric, ferroelectric and piezoelectric properties were investigated as a function of the LN content. The X-ray diffraction patterns revealed the formation of a single-phase perovskite structure for all the LN-modified BNT-BZ ceramics in this study. The results indicate that the LN substitution into BNT-BZ3 induces a transition from a ferroelectric to a diffuse and/or relaxor state accompanying a field-induced strain of 0.20% for x = 0.05 at an applied field of 6 kV/mm. The corresponding dynamic piezoelectric coefficient for this composition was ( S max/ E max = 333 pm/V). A significant reduction of the coercive field ( E c) and enhancement of the piezoelectric constant ( d 33) from 98 pC/N for x = 0 to 117 pC/N x = 0.01 was observed.

  9. Vortex Domains in Ferroelectric Nano-Structures

    NASA Astrophysics Data System (ADS)

    Scott, James F.

    2011-03-01

    Recently the study of submicron-diameter ferroelectric disks and squares and rectangles fabricated from films of ca. 100-300 nm thick have revealed usual domain patterns, qualitatively different from the stripe domains commonly studied in macroscopic specimens in the past. These include doughnut-shaped domains, four-fold vertex closure domains, and fractal domains. The static configurations offer a variety of puzzles, and the structures differ from those in magnetic vortex domains, presumably due to the much larger anisotropy in ferroelectrics, which generally prohibits true vortex configurations with polarization forced out of plane. The dynamics also differ qualitatively from early studies: For decades ferroelectrics were thought to be highly Ising-like, but recent data and theoretical simulations favor Bloch walls and more Heisenberg-like kinetics. This talk will include data from Alina Schilling and Marty Gregg in Belfast, Marin Alexe in Halle, and modeling from Hlinka and Marton in Prague and Bellaiche and Prosandeev in Arkansas.

  10. Nickel nanoparticles doped ferroelectric liquid crystal composites

    NASA Astrophysics Data System (ADS)

    Neeraj; Raina, K. K.

    2013-01-01

    With the advance of nanoparticles-liquid crystal composites, it became increasingly interesting to measure the various physical parameters, preferably near the transition temperature. In this research work, fine nickel nanoparticles with 2-8 nm size distribution were synthesized by chemical reduction of nickel hydrazine complex in aqueous solution at 60 °C. A small concentration of 0.5 wt.% of nickel nanoparticles dispersed in a novel ferroelectric liquid crystal mixture showed improved transmittance and fast switching response. Moreover, nickel addition indicates a slight increase in the conductivity of the ferroelectric sample. These studies indicate the occurrence of strong dipole interactions between metallic nanoparticles and ferroelectric liquid crystal molecules in the presence of applied electric field.

  11. Multiferroics: a magnetic twist for ferroelectricity

    NASA Astrophysics Data System (ADS)

    Cheong, Sang-Wook; Mostovoy, Maxim

    2007-01-01

    Magnetism and ferroelectricity are essential to many forms of current technology, and the quest for multiferroic materials, where these two phenomena are intimately coupled, is of great technological and fundamental importance. Ferroelectricity and magnetism tend to be mutually exclusive and interact weakly with each other when they coexist. The exciting new development is the discovery that even a weak magnetoelectric interaction can lead to spectacular cross-coupling effects when it induces electric polarization in a magnetically ordered state. Such magnetic ferroelectricity, showing an unprecedented sensitivity to ap plied magnetic fields, occurs in 'frustrated magnets' with competing interactions between spins and complex magnetic orders. We summarize key experimental findings and the current theoretical understanding of these phenomena, which have great potential for tuneable multifunctional devices.

  12. Multiferroics: a magnetic twist for ferroelectricity.

    PubMed

    Cheong, Sang-Wook; Mostovoy, Maxim

    2007-01-01

    Magnetism and ferroelectricity are essential to many forms of current technology, and the quest for multiferroic materials, where these two phenomena are intimately coupled, is of great technological and fundamental importance. Ferroelectricity and magnetism tend to be mutually exclusive and interact weakly with each other when they coexist. The exciting new development is the discovery that even a weak magnetoelectric interaction can lead to spectacular cross-coupling effects when it induces electric polarization in a magnetically ordered state. Such magnetic ferroelectricity, showing an unprecedented sensitivity to ap plied magnetic fields, occurs in 'frustrated magnets' with competing interactions between spins and complex magnetic orders. We summarize key experimental findings and the current theoretical understanding of these phenomena, which have great potential for tuneable multifunctional devices. PMID:17199121

  13. Large piezoelectric strains from polarization graded ferroelectrics

    NASA Astrophysics Data System (ADS)

    Zhong, S.; Ban, Z.-G.; Alpay, S. P.; Mantese, J. V.

    2006-10-01

    The potential applications of polarization graded ferroelectrics as high performance sensors and actuators are theoretically investigated. A static bending can be expected in polarization graded ferroelectric plates, forming a vertical displacement. This is due to the built-in strain gradient that arises from the grading of the composition and concomitantly, the spontaneous self-strain. Numerical results of two compositionally graded ferroelectrics, BaTiO3-Ba1-xSrxTiO3 and PbTiO3-Pb1-xZrxTiO3, show a high dynamic response of the displacement under an external electric field, yielding as much as ˜23% strain at 50kV /cm in PbTiO3-Pb0.6Zr0.4TiO3, which is comparable to large displacement actuators formed from ceramic/ceramic and ceramic/metal multilayer mesomaterials.

  14. Minimization of fatigue in ferroelectric films

    SciTech Connect

    Desu, S.B. [Virginia Tech, Blacksburg, VA (United States)

    1996-12-31

    On the basis of a quantitative fatigue model, various methods to minimize fatigue in oxide ferroelectric films are discussed. The model attributes fatigue to domain pinning by space charge that is caused by oxygen vacancy entrapment at the interfaces (e.g., electrode-ferroelectric, domain boundaries etc.). Based on this model, it has been demonstrated that fatigue can be minimized by : (a) using conductive oxide electrodes (e.g., RuO{sub 2}) that prevent space charge formation at the interfaces; (b) by addition of donor dopants (e.g., Nb, La in Pb(Zr{sub x}Ti{sub 1-x})O{sub 3}) that reduce the oxygen vacancy concentration and (c) by utilizing ferroelectric materials (e.g., SrBi{sub 2}(Ta{sub x}Nb{sub 1-x}){sub 2}O{sub 9}) that have a low intrinsic defect concentration.

  15. Negative differential conductivity in thin ferroelectric films

    NASA Astrophysics Data System (ADS)

    Podgorny, Yury; Vorotilov, Konstantin; Sigov, Alexander

    2014-11-01

    A phenomenon of negative differential conductivity in ferroelectric thin films is discussed. We proposed that the reason is polarization recovery current arising at current-voltage I(V) measurements as a result of polarization relaxation after pre-polarization of ferroelectric film. Simulation of this current by Weibull distribution provides a good correlation with the experimental data. The obtained values of the recovered polarization Prec and the field strength Erec at which the recovery polarization current reaches maximum do not depend on the voltage sweep rate and are well correlated with the values of polarization relaxation Prel and coercive field strength Ec obtained from dielectric hysteresis loop. It is shown that the current density due to polarization recovery Jrec may exceed by about an order the ohmic current density J? in ferroelectric film at Ec.

  16. Ferroelectric polarization relaxation in Au/Cu2O/ZnO/BiFeO3/Pt heterostructure

    NASA Astrophysics Data System (ADS)

    Fan, Zhen; Xiao, Juanxiu; Yao, Kui; Zeng, Kaiyang; Wang, John

    2015-03-01

    The stability of polarization in ferroelectric BiFeO3 thin film stacked with a p-n junction of Cu2O/ZnO was studied in the Au/Cu2O/ZnO/BiFeO3/Pt heterostructure. It was observed that the downward ferroelectric polarization of BiFeO3 gradually relaxes once the external electric field is removed, which is driven by the depolarization effect induced by the reduction of compensating charges due to the charge redistribution within Cu2O/ZnO. This work contributes to an improved understanding on the polarization behavior in multilayer thin film structures comprising ferroelectrics and p-n junctions for guiding relevant device design and performance analysis.

  17. Are lithium niobate (LiNbO3) and lithium tantalate (LiTaO3) ferroelectrics bioactive?

    PubMed

    Vilarinho, Paula Maria; Barroca, Nathalie; Zlotnik, Sebastian; Félix, Pedro; Fernandes, Maria Helena

    2014-06-01

    The use of functional materials, such as ferroelectrics, as platforms for tissue growth in situ or ex situ, is new and holds great promise. But the usage of materials in any bioapplication requires information on biocompatibility and desirably on bioactive behavior when bone tissue engineering is envisaged. Both requirements are currently unknown for many ferroelectrics. Herein the bioactivity of LiNbO3 and LiTaO3 is reported. The formation of apatite-like structures on the surface of LiNbO3 and LiTaO3 powders after immersion in simulated body fluid (SBF) for different soaking periods indicates their bioactive potential. The mechanism of apatite formation is suggested. In addition, the significant release of lithium ions from the ferroelectric powders in the very first minutes of soaking in SBF is examined and ways to overcome this likely hurdle addressed. PMID:24863240

  18. Modified Johnson model for ferroelectric lead lanthanum zirconate titanate at very high fields and below Curie temperature.

    SciTech Connect

    Narayanan, M.; Tong, S.; Ma, B.; Liu, S.; Balachandran, U. (Energy Systems)

    2012-01-01

    A modified Johnson model is proposed to describe the nonlinear field dependence of the dielectric constant ({var_epsilon}-E loop) in ferroelectric materials below the Curie temperature. This model describes the characteristic ferroelectric 'butterfly' shape observed in typical {var_epsilon}-E loops. The predicted nonlinear behavior agreed well with the measured values in both the low- and high-field regions for lead lanthanum zirconate titanate films. The proposed model was also validated at different temperatures below the ferroelectric-to-paraelectric Curie point. The anharmonic coefficient in the model decreased from 6.142 x 10{sup -19} cm{sup 2}/V{sup 2} to 2.039 x 10{sup -19} cm{sup 2}/V{sup 2} when the temperature increased from 25 C to 250 C.

  19. Uncooled monolithic ferroelectric IRFPA technology

    NASA Astrophysics Data System (ADS)

    Belcher, James F.; Hanson, Charles M.; Beratan, Howard R.; Udayakumar, K. R.; Soch, Kevin L.

    1998-10-01

    Once relegated to expensive military platforms, occasionally to civilian platforms, and envisioned for individual soldiers, uncooled thermal imaging affords cost-effective solutions for police cars, commercial surveillance, driving aids, and a variety of other industrial and consumer applications. System prices are continuing to drop, and swelling production volume will soon drive prices substantially lower. The impetus for further development is to improve performance. Hybrid barium strontium titanate (BST) detectors currently in production are relatively inexpensive, but have limited potential for improved performance. The MTF at high frequencies is limited by thermal conduction through the optical coating. Microbolometer arrays in development at Raytheon have recently demonstrated performance superior to hybrid detectors. However, microbolometer technology lacks a mature, low-cost system technology and an abundance of upgradable, deployable system implementations. Thin-film ferroelectric (TFFE) detectors have all the performance potential of microbolometers. They are also compatible with numerous fielded and planned system implementations. Like the resistive microbolometer, the TFFE detector is monolithic; i.e., the detector material is deposited directly on the readout IC rather than being bump bonded to it. Imaging arrays of 240 X 320 pixels have been produced, demonstrating the feasibility of the technology.

  20. Ferroelectric soft mode of polar ZnTiO3 investigated by Raman spectroscopy at high pressure

    NASA Astrophysics Data System (ADS)

    Ruiz-Fuertes, J.; Winkler, B.; Bernert, T.; Bayarjargal, L.; Morgenroth, W.; Koch-Müller, M.; Refson, K.; Milman, V.; Tamura, N.

    2015-06-01

    We explore the vibrational behavior and stability of ferroelectric ZnTiO3 under high pressure by Raman spectroscopy and second-harmonic-generation (SHG) measurements. Ab initio lattice-dynamics calculations have been employed to solve a controversy concerning the phonon-dispersion relations of ZnTiO3 and to carry out an assignment of the Raman modes. A ferroelectric to paraelectric phase transition has been observed both by Raman spectroscopy and SHG at 20.8 GPa. Contrary to LiNbO3, the ferroelectric soft mode of ZnTiO3 has been found to be the A1(2) and not the A1(1) mode. The calculated eigenvectors show that the A1(2) mode of ferroelectric ZnTiO3 is an antiphase vibration of the Ti atom against the oxygen framework, similar to the soft modes observed in ferroelectric perovskites. The SHG signal of ZnTiO3 has been found to be independent of the grain size below the phase transition, indicating that ZnTiO3 is a phase-matchable compound.

  1. Carrier Density Modulation in Ge Heterostructure by Ferroelectric Switching

    SciTech Connect

    Ponath, Patrick [University of Texas at Austin; Fredrickson, Kurt [University of Texas at Austin; Posadas, Agham B. [University of Texas at Austin; Ren, Yuan [University of Texas at Austin; Vasudevan, Rama K [ORNL; Okatan, Mahmut Baris [ORNL; Jesse, Stephen [ORNL; Aoki, Toshihiro [Arizona State University; McCartney, Martha [Arizona State University; Smith, David J [Arizona State University; Kalinin, Sergei V [ORNL; Lai, Keji [University of Texas at Austin; Demkov, Alexander A. [University of Texas at Austin

    2015-01-01

    The development of nonvolatile logic through direct coupling of spontaneous ferroelectric polarization with semiconductor charge carriers is nontrivial, with many issues, including epitaxial ferroelectric growth, demonstration of ferroelectric switching, and measurable semiconductor modulation. Here we report a true ferroelectric field effect carrier density modulation in an underlying Ge(001) substrate by switching of the ferroelectric polarization in the epitaxial c-axis-oriented BaTiO3 (BTO) grown by molecular beam epitaxy (MBE) on Ge. Using density functional theory, we demonstrate that switching of BTO polarization results in a large electric potential change in Ge. Aberration-corrected electron microscopy confirms the interface sharpness, and BTO tetragonality. Electron-energy-loss spectroscopy (EELS) indicates the absence of any low permittivity interlayer at the interface with Ge. Using piezoelectric force microscopy (PFM), we confirm the presence of fully switchable, stable ferroelectric polarization in BTO that appears to be single domain. Using microwave impedance microscopy (MIM), we clearly demonstrate a ferroelectric field effect.

  2. Static ferroelectric memory transistor having improved data retention

    DOEpatents

    Evans, Jr., Joseph T. (13609 Verbena Pl., N.E., Albuquerque, NM 87112); Warren, William L. (7716 Wm. Moyers Ave., NE., Albuquerque, NM 87112); Tuttle, Bruce A. (12808 Lillian Pl., NE., Albuquerque, NM 87112)

    1996-01-01

    An improved ferroelectric FET structure in which the ferroelectric layer is doped to reduce retention loss. A ferroelectric FET according to the present invention includes a semiconductor layer having first and second contacts thereon, the first and second contacts being separated from one another. The ferroelectric FET also includes a bottom electrode and a ferroelectric layer which is sandwiched between the semiconductor layer and the bottom electrode. The ferroelectric layer is constructed from a perovskite structure of the chemical composition ABO.sub.3 wherein the B site comprises first and second elements and a dopant element that has an oxidation state greater than +4 in sufficient concentration to impede shifts in the resistance measured between the first and second contacts with time. The ferroelectric FET structure preferably comprises Pb in the A-site. The first and second elements are preferably Zr and Ti, respectively. The preferred B-site dopants are Niobium, Tantalum, and Tungsten at concentrations between 1% and 8%.

  3. Ferroelectric Cathodes in Transverse Magnetic Fields

    SciTech Connect

    Alexander Dunaevsky; Yevgeny Raitses; Nathaniel J. Fisch

    2002-07-29

    Experimental investigations of a planar ferroelectric cathode in a transverse magnetic field up to 3 kGs are presented. It is shown that the transverse magnetic field affects differently the operation of ferroelectric plasma cathodes in ''bright'' and ''dark'' modes in vacuum. In the ''bright'' mode, when the surface plasma is formed, the application of the transverse magnetic field leads to an increase of the surface plasma density. In the ''dark'' mode, the magnetic field inhibits the development of electron avalanches along the surface, as it does similarly in other kinds of surface discharges in the pre-breakdown mode.

  4. Switching Characteristics of Ferroelectric Transistor Inverters

    NASA Technical Reports Server (NTRS)

    Laws, Crystal; Mitchell, Coey; MacLeod, Todd C.; Ho, Fat D.

    2010-01-01

    This paper presents the switching characteristics of an inverter circuit using a ferroelectric field effect transistor, FeFET. The propagation delay time characteristics, phl and plh are presented along with the output voltage rise and fall times, rise and fall. The propagation delay is the time-delay between the V50% transitions of the input and output voltages. The rise and fall times are the times required for the output voltages to transition between the voltage levels V10% and V90%. Comparisons are made between the MOSFET inverter and the ferroelectric transistor inverter.

  5. Domain specific phenomena at ferroelectric perovskite surfaces

    NASA Astrophysics Data System (ADS)

    Li, Dongbo

    Ferroelectric compounds are the basis of traditional electronic ceramic devices. The ferroelectric response is being explored as components in emerging nanoscale devices. At these length scales, the fundamental aspects of atomic structure and reactions at ferroelectric surfaces are critical to a range of device applications. In this dissertation, Scanning Probe Microscopy was employed to study the domain specific phenomena at ferroelectric perovskite surfaces. The primary aim of these studies is to acquire a detailed understanding of polarization related processes at ferroelectric surfaces and to generate new insights into basic mechanisms behind them. Using a combination of scanning tunneling microscopy (STM), non-contact atomic force microscopy (nc-AFM), and low energy electron diffraction (LEED), surface structure and stability of BaTiO3 (001) was investigated. It is discovered that this surface adopts a family of reconstructions, each depending on thermo-chemical history. Surface reconstruction evolution with temperature and chemical potential of environments was understood through density function theoretical (DFT) calculations that predict the surface diagram with thermodynamically most favorable surface phases under varying conditions. Theoretical calculations were done by A. Kolpak and A. Rappe. Comparisons of the results from the calculations with the STM and nc-AFM observations were used to construct atomic models for the reconstructed surfaces. The relationship between atomic domain polarization and local surface interactions was studied with two approaches. Using piezoforce microscopy (PFM) and scanning surface potential microscopy (SSPM), the interaction between electron injection and ferroelectric lattice was investigated. The observed polarization reorientation through surface charging was further explored to control domain structure at the nano-meter scale. The effect of electron beam dosage, current, and voltage was quantified for PZT thin films. By coupling the capability of scanning probes and/or electron beams to control the domain polarization at the nanometer scale to the specificity of photochemical reactions on ferroelectric domains, nanostructures with magnetic properties were assembled at ferroelectric surfaces. Using SSPM, the effect of polarization orientation on CO2 adsorption was examined and quantified, leading to the discovery of a sticking coefficient difference by a factor of 4 for opposite domains in both BaTiO 3 and lead zirconate titanate (PZT) crystals. The differences were discussed in terms of the possible adsorption mechanisms at surfaces. The molecular adsorption mechanism was deduced with reference to temperature programmed desorption (TPD) measurements from M. He and J. Vohs and DFT calculations from A. Kolpak and A. Rappe.

  6. Effect of stoichiometry on the dielectric properties and soft mode behavior of strained epitaxial SrTiO3 thin films on DyScO3 substrates

    SciTech Connect

    Lee, Che-Hui [Pennsylvania State University, University Park, PA; Skoromets, Volodymyr [Institute of Physics, Czech Republic; Biegalski, Michael D [ORNL; Lei, Shiming [Pennsylvania State University, University Park, PA; Haislmaier, Ryan [Pennsylvania State University, University Park, PA; Uecker, Reinhard [Leibniz Institute for Crystal Growth (IKZ); Bernhagen, Margitta [Leibniz Institute for Crystal Growth (IKZ); Xi, Xiaoxing [Temple University; Gopalan, Venkatraman [Pennsylvania State University, University Park, PA; Marti, Xavier [Institute of Physics, Czech Republic; Kamba, Stanislav [Institute of Physics, Czech Republic; Kuzel, Petr [Institute of Physics, Czech Republic; Schlom, Darrell [Cornell University

    2013-01-01

    The effect of stoichiometry on the dielectric properties and soft mode behavior of strained epitaxial Sr1-xTiO3 films grown on DyScO3 substrates is reported. Direct comparisons between nominally stoichiometric and non-stoichiometric films have been performed through measurements of lattice parameters, temperature-dependent permittivities, second harmonic generation, and terahertz dielectric spectra. The nominally stoichiometric film shows dispersion-free low-frequency permittivity with a 23 sharp maximum and pronounced soft mode behavior. Our results suggest that strained perfectlystoichiometric SrTiO3 films should not show relaxor behavior and that relaxor behavior emergesfrom defect dipoles that arise from non-stoichiometry in the highly polarizable strained SrTiO3 matrix

  7. Effects of the poling process on dielectric, piezoelectric, and ferroelectric properties of lead zirconate titanate

    NASA Astrophysics Data System (ADS)

    Prewitt, Anderson D.

    Smart materials are widely used in many of today's relevant technologies such as nano and micro electromechanical systems (NEMS and MEMS), sensors, actuators, nonvolatile memory, and solid state devices. Many of these systems rely heavily on the electromechanical properties of certain smart materials, such as piezoelectricity and ferroelectricity. By definition, piezoelectricity is a mechanical stress in a material that produces an electric displacement (known as the direct piezoelectric effect) or electrical charge in a material which produces a mechanical strain (known as the converse piezoelectric effect). Ferroelectricity is a sub-class of piezoelectricity in which the polarization occurs spontaneously and the dipoles can be reoriented. Domain walls are the nanoscale regions separating two finite distinctively polarized areas in a ferroelectric. The reorientation of polarization in a material is called the poling process and many factors can influence the effectiveness of this process. A more fundamental understanding of how electrical and mechanical loading changes the domain structure of these materials could lead to enhanced properties such as increased energy transduction and decreased nonlinear behavior. This research demonstrates the influence of mechanical pressure and electrical field during and after the poling process on domain walls. The effects of strong mechanical forces on large-scale domain switching and weak cyclic forces on small-scale domain wall motion are investigated to show how they affect the macroscopic behavior of these materials. Commercial lead zirconate titanate ceramics were studied under various poling conditions and the effect of domain wall motion on the piezoelectric, dielectric, and ferroelectric properties was investigated. Polarization and strain measurements from samples poled at specific conditions and converse piezoelectric coefficient and dielectric permittivity data was extracted and interpreted in the context of Rayleigh Law. Direct d33 was also measured. Mechanical loading measurements on the samples were conducted in situ during neutron diffraction experiments to determine how the domain structure behaved for the various poling conditions. The behavior of unpoled and poled samples under load was investigated. The goal of this research is to develop a better understanding of the ferroelectric poling process and its influence on domain wall behavior in order to better engineer material and device properties. Experimental results have shown that significant changes occur in the electromechanical behavior of the material depending on the poling conditions. These results provide insight on how to better design materials and devices with enhanced performance, improved capacity, and less degradation as a result of mechanical stress and electrical fields. Possible microstructural origins for this behavior are discussed.

  8. Probing Polarization Dynamics and Energy Dissipation in Ferroelectric Polymers on the Nanoscale

    NASA Astrophysics Data System (ADS)

    Kalinin, Sergei V.

    2007-03-01

    Ferroelectric polymers are emerging as prominent materials for ultrasonic actuators, gate materials for non-volatile ferroelectric memories, and energy storage. The nature of ferroelectricity in polymers is significantly different from that in inorganic perovskites, resulting in significant interest to elementary mechanism of switching and the role of local microstructure. In this talk, I briefly delineate Piezoresponse Force Microscopy and Spectroscopy as applied for characterization of Langmuir-Blodgett ferroelectric PVDF polymer films. The slow polarization switching in PVDF can be attributed to the grain-by grain switching mechanism. Recent advances in PFM probing of polarization dynamics and electromechanical energy dissipation are discussed. In particular, switching spectroscopy PFM is used to probe the spatial variability of switching behavior and role of grain boundaries on switching. Local energy dissipation imaging through the changes of the Q-factor of electrically driven cantilever in contact with the surface is developed to study energy losses in the ferroelectric switching processes. In collaboration with Brian J. Rodriguez and Stephen Jesse, Materials Sciences and Technology Division and The Center for Nanophase Materials Sciences, Oak Ridge National Laboratory; Jihee Kim and Steven Ducharme, Department of Physics and Astronomy, Nebraska Center for Materials and Nanoscience University of Nebraska, Lincoln. Research was supported by the U.S. Department of Energy Office of Basic Energy Sciences Division of Materials Sciences and Engineering (SVK, BJR, and SJ) and user proposal of The Center for Nanophase Materials Sciences (JK and SD) and was performed at Oak Ridge National Laboratory which is operated by UT-Battelle, LLC.

  9. Ferroelectric Material Application: Modeling Ferroelectric Field Effect Transistor Characteristics from Micro to Nano

    NASA Technical Reports Server (NTRS)

    MacLeod, Todd, C.; Ho, Fat Duen

    2006-01-01

    All present ferroelectric transistors have been made on the micrometer scale. Existing models of these devices do not take into account effects of nanoscale ferroelectric transistors. Understanding the characteristics of these nanoscale devices is important in developing a strategy for building and using future devices. This paper takes an existing microscale ferroelectric field effect transistor (FFET) model and adds effects that become important at a nanoscale level, including electron velocity saturation and direct tunneling. The new model analyzed FFETs ranging in length from 40,000 nanometers to 4 nanometers and ferroelectric thickness form 200 nanometers to 1 nanometer. The results show that FFETs can operate on the nanoscale but have some undesirable characteristics at very small dimensions.

  10. Semiconductor-ferroelectric nonvolatile memory using anomalous high photovoltages in ferroelectric ceramics

    NASA Technical Reports Server (NTRS)

    Brody, P. S.

    1981-01-01

    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.

  11. Simulation of oxygen vacancy induced phenomena in ferroelectric thin films

    NASA Astrophysics Data System (ADS)

    Li, Kwok Tung; Lo, Veng Cheong

    2005-02-01

    The role of oxygen vacancy in lead-titanate-zirconate ferroelectric thin film has been numerically simulated using the two-dimensional four-state Potts model. On one hand, the presence of an oxygen vacancy in a perovskite cell strongly influences the displacement of the Ti4+ ion. Hence the vacancy-dipole coupling must be considered in the switching mechanism. On the other hand, a space charge layer is established by the inhomogeneous distribution of oxygen vacancies through trapping charge carriers. Consequently, the thickness dependence of the coercive field and remanent polarization are reproduced in the presence of this oxygen vacancy distribution. Frequency, temperature, and driving voltage-dependent polarization fatigue behaviors are also simulated.

  12. Sub-critical field domain reversal in epitaxial ferroelectric films

    NASA Astrophysics Data System (ADS)

    Chen, Jason; Gruverman, Alexei; Morozovska, Anna N.; Valanoor, Nagarajan

    2014-09-01

    Domain nucleation in epitaxial (001)-oriented Pb(Zr0.2TiO0.8)O3 ultrathin ferroelectric films under a sub-critical field regime is investigated by means of piezoresponse force microscopy (PFM). Analytical fits to the domain radius and velocity as a function of time indicate that 180° domain nucleation and growth under a biased PFM tip exhibit a thermally activated, creep behavior. It is also found that an electric field of less than half of the local coercive (or critical) field E c l o c detected by PFM can create stable domains under prolonged bias application. Under these sub-critical bias conditions, it is the temporal evolution of the local electric-field profile due to the slow drift of screening charges or defects (e.g., ionic vacancies) that dictates domain nucleation and growth.

  13. Ferroelectric-field-effect-enhanced electroresistance in metal/ferroelectric/semiconductor tunnel junctions.

    PubMed

    Wen, Zheng; Li, Chen; Wu, Di; Li, Aidong; Ming, Naiben

    2013-07-01

    Ferroelectric tunnel junctions (FTJs), composed of two metal electrodes separated by an ultrathin ferroelectric barrier, have attracted much attention as promising candidates for non-volatile resistive memories. Theoretical and experimental works have revealed that the tunnelling resistance switching in FTJs originates mainly from a ferroelectric modulation on the barrier height. However, in these devices, modulation on the barrier width is very limited, although the tunnelling transmittance depends on it exponentially as well. Here we propose a novel tunnelling heterostructure by replacing one of the metal electrodes in a normal FTJ with a heavily doped semiconductor. In these metal/ferroelectric/semiconductor FTJs, not only the height but also the width of the barrier can be electrically modulated as a result of a ferroelectric field effect, leading to a greatly enhanced tunnelling electroresistance. This idea is implemented in Pt/BaTiO3/Nb:SrTiO3 heterostructures, in which an ON/OFF conductance ratio above 10(4), about one to two orders greater than those reported in normal FTJs, can be achieved at room temperature. The giant tunnelling electroresistance, reliable switching reproducibility and long data retention observed in these metal/ferroelectric/semiconductor FTJs suggest their great potential in non-destructive readout non-volatile memories. PMID:23685861

  14. Ferroelectric control of spin injection across the ferromagnet/ferroelectric interface

    NASA Astrophysics Data System (ADS)

    Liu, Xiaohui; Burton, J. D.; Tsymbal, Evgeny

    2014-03-01

    Magnetoelectric coupling has become one of the most attractive fields in modern materials research due their promise to electrically control spintronics-based devices. Previous investigations have shown that at the ferromagnet/ferroelectric interface, magnetization could be tuned by the reversal of ferroelectric polarization. We had previously predicted that ferroelectric polarization reversal can control the nature of the resistive contact at the SrRuO3/n-BaTiO3 heterojunction interface, going from the Ohmic to Schottky regimes with reversal of ferroelectric polarization. It is known, however, that SrRuO3 displays robust ferromagnetism below the Curie temperature of about 160K. In this work, using first-principles density functional calculations, we explore the effect of ferroelectric polarization of spin-polarized transmission across the SrRuO3/n-BaTiO3 interface. Our study reveals that the interface transmission is negatively spin-polarized, and that ferroelectric polarization reversal leads to a change in spin polarization from -65% for the Ohmic contact to -98% for the Schottky contact. This sizeable change in the spin polarization could provide an interesting non-volatile mechanism to electrically control spin injection into semiconductor-based spintronics devices.

  15. Grain surface polarization: ferroelectric mantles?

    NASA Astrophysics Data System (ADS)

    Cassidy, A. M.; Balog, R.; Field, D.; Jones, N.; Plekan, O.

    2011-05-01

    Recent experiments have shown that films of molecules such as nitrous oxide, propane etc. spontaneously harbour very high electric fields exceeding 108 Vm-11 . This arises through dipole alignment with polarization at the film surface, giving rise to large voltages at the surface. Potentials are measured with a cold electron beam technique using the ASTRID synchrotron at Aarhus. The electric field within the film is constant. Since a spontaneous field is generated the films show ferroelectric properties. Figure 1 shows the amount of potential added per added monolayer (ML) of material, in this case on a gold surface. The absolute value of potential and the field generated is independent of the nature of the surface. If we assume the 'standard' onion skin model of mantle accretion on grains, then the outer layer of grains will be composed of almost pure CO. If a large fraction of CO is adsorbed into the mantle, as is the case in B682, the mantle of pure CO will be typically 10-100 MLs thick. We mark, in Figure 1, the position of CO with respect to dipole moment. It would therefore seem highly probable that CO would show dipole alignment, although we have not yet been able to measure this for the purely technical reason that our apparatus will not operate below 38K and CO requires 22K to condense. Thus the surface of such grains would show a positive potential, given that the O-atom sticks up (McCoustra, private communication). The polarization on the surface is expected to be >10-4 Cm-2, giving 75 apparent charges on a 0.1 micron radius grain, which will decay as electrons are captured. Coupled with an electric field within the CO ice mantle of > 10^7 Vm-1, this may have interesting implications in grain properties and their associated chemistry. This will be discussed in our contribution.

  16. Permissible symmetries of multi-domain configurations in perovskite ferroelectric crystals

    E-print Network

    Cao, Wenwu

    Permissible symmetries of multi-domain configurations in perovskite ferroelectric crystals Jiri through domain engineering are specified for perovskite ferroelectric crystals having tetragonal walls . Many useful ferroelectric materials have the so-called perovskite structure, which contains

  17. Magnetoelectric properties of 0.1Bi0.95Dy0.05FeO3-0.9Pb(Fe2\\/3W1\\/3)O3 multiferroic

    Microsoft Academic Search

    A. Stoch; P. Stoch; J. Kulawik; P. Zieli ski; J. Maurin

    2011-01-01

    Pb-based complex perovskites with Fe3+ like Pb(Fe2\\/3W1\\/3)O3 (PFW) were found to be interesting because of their unique properties such as relaxor and magnetoelectric behavior. PFW is ferroelectric with ferroelectric Curie temperature TC between 150 and 200 K and at the same time is antiferromagnetic with magnetic Neel temperature about 400 K. BiFeO3 is a well known perovskite compound which exhibits

  18. Residual ferroelectricity, piezoelectricity, and flexoelectricity in barium strontium titanate tunable dielectrics

    NASA Astrophysics Data System (ADS)

    Garten, Lauren M.

    Loss reduction is critical to the development of Ba 1-xSrxTiO3 (BST) thin film tunable microwave dielectrics. This work addresses mechanisms of loss and performance of Ba1-xSr xTiO3, such as residual ferroelectricity, enhanced flexocoupling, and dc electric field induced piezoelectricity. The presence of residual ferroelectricity --a persistent ferroelectric response above the global phase transition temperature, adds a contribution to dielectric loss from either motion of domain walls or the boundaries of micropolar regions, degrading the tunable performance over a wide frequency range. Rayleigh behavior as a function of temperature was used to track the ferroelectric behavior of BST materials through the ferroelectric to paraelectric transition temperature. The irreversible Rayleigh parameter serve as a metric for the presence of ferroelectricity because this response is dependent on the presence of domain walls, cluster boundaries or phase boundaries. Chemical solution deposited Ba0.7Sr0.3TiO3 films, with relative tunabilities of 86% over 250kV/cm at 100kHz, demonstrated residual ferroelectricity at least 65°C above the ostensible paraelectric transition temperature. The Rayleigh behavior was further corroborated with second harmonic generation, polarization-electric field hysteresis loops and the frequency dependence of the Rayleigh response. The temperature extent of residual ferroelectricity in sputtered and chemical solution deposited films and bulk ceramics was investigated as a function of chemical inhomogeneity on the A-site using electron energy loss spectroscopy. All samples showed some residual ferroelectricity, where the temperature extent was a function of the sample processing. The application of AC electric field for residual ferroelectric measurements of these samples lead to a 100% increase in loss for ac fields exceeding 10kV/cm at room temperature. The presence of residual ferroelectricity in BST also correlates to the increased flexoelectric response in these materials. Residual ferroelectricity is observed in barium strontium titanate ceramics 30°C above the global phase transition temperature, in the same temperature range in which anomalously large flexoelectric coefficients are reported. The application of a strain gradient in this temperature range was shown to lead to strain gradient-induced poling, or flexoelectric poling, enhancing the flexoelectric response. Flexoelectric poling was observed by the development of a remanent polarization in flexoelectric measurements upon the removal of the applied strain gradient. Additionally, an induced d33 piezoelectric response was observed in samples after the removal of the applied strain gradient, indicating that the polarization was realigned during flexoelectric measurements. Flexoelectric poling lead to the production of an internal bias of 9 kV/m. It is concluded that residual ferroelectric response considerably enhances the observed flexoelectric response. In order to investigate the effects of dc electric field induced piezoelectricity, metrology was designed, developed and calibrated for the measurement of the e31,f piezoelectric coefficient as a function of applied electric field and strain. This allowed for direct measurements of the field-induced piezoelectric response for Ba0.7Sr0.3TiO3 (70:30) and Ba 0.6Sr0.4TiO3 (60:40) thin films on MgO and silicon. The relative dielectric tunabilities for the 70:30 and 60:40 composition on MgO were 83% and 70% respectively, with a dielectric loss of 0.011 and 0.004 at 100 kHz respectively. A linear increase in induced piezoelectricity with field to --3.0 C/m2 and --1.5 C/m2 at 110 kV/cm was observed in 60:40 BST on MgO and 70:30 BST on Si. Large and hysteretic piezoelectric and tuning responses were observed in the 70:30 BST thin films on MgO. This was consistent with the irreversible Rayleigh behavior, indicating a ferroelectric contribution to the piezoelectric and dielectric response 40°C above the global paraelectric transition temperature. This information should enable advancements in tunable

  19. Inductive crystallization effect of atomic-layer-deposited Hf0.5Zr0.5O2 films for ferroelectric application.

    PubMed

    Zhang, Xun; Chen, Lin; Sun, Qing-Qing; Wang, Lu-Hao; Zhou, Peng; Lu, Hong-Liang; Wang, Peng-Fei; Ding, Shi-Jin; Zhang, David Wei

    2015-01-01

    Ferroelectric Hf x Zr1-x O2 thin films are considered promising candidates for future lead-free CMOS-compatible ferroelectric memory application. The inductive crystallization behaviors and the ferroelectric performance of Hf0.5Zr0.5O2 thin films prepared by atomic layer deposition were investigated. Inductive crystallization can be induced by the film growth condition and appropriate top electrode selection. In this work, a Ni/Hf0.5Zr0.5O2/Ru/Si stack annealed at 550°C for 30 s in N2 ambient after the Ni top electrode has been deposited was manufactured, and it shows the best ferroelectric hysteresis loop in the dielectric thickness of 25 nm, with a remanent polarization value of 6 ?C/cm(2) and a coercive field strength of 2.4 MV/cm measured at 10 kHz. Endurance, retention, and domain switching current characteristics were evaluated well for potential application in the field of ferroelectric field effect transistor (FeFET) and nonvolatile ferroelectric memories (FeRAM). PMID:25852322

  20. Graphene Ferroelectric Heterostructures Santosh Raghavan1

    E-print Network

    Dalang, Robert C.

    Graphene Ferroelectric Heterostructures Santosh Raghavan1 , Dr. Jean-Savin Heron2 , Dr. Igor] Laboratory of Nanoscale Electronics and Structures, IEL, EPFL S D1 2 Doped Silicon SiO2 Graphene 3 4 1 2S D L Introduction Working Principle Graphene PVDF (-TrFE) PFM Measurements Retention Measurements Conclusion

  1. Local Polarization Dynamics in Ferroelectric Materials

    SciTech Connect

    Kalinin, Sergei V [ORNL; Morozovska, A. N. [National Academy of Science of Ukraine, Kiev, Ukraine; Chen, L. Q. [Pennsylvania State University; Rodriguez, Brian J [ORNL

    2010-01-01

    Ferroelectrics and multiferroics have recently emerged as perspective materials for information technology and data storage applications. The combination of extremely narrow domain wall width and the capability to manipulate polarization by electric field opens the pathway towards ultrahigh (>10 TBit/in2) storage densities and small (sub-10 nm) feature sizes. The coupling between polarization and chemical and transport properties enables applications in ferroelectric lithography and electroresistive devices. The progress in these applications, as well as fundamental studies of polarization dynamics and the role of defects and disorder on domain nucleation and wall motion, requires the capability to probe these effects on the nanometer scale. In this review, we summarize recent progress in applications of Piezoresponse Force Microscopy (PFM) for imaging, manipulation, and spectroscopy of ferroelectric switching processes. We briefly introduce the principles and relevant instrumental aspects of PFM, with special emphasis on resolution and information limits. The local imaging studies of domain dynamics, including local switching and relaxation accessed through imaging experiments, and spectroscopic studies of polarization switching, are discussed in detail. Finally, we briefly review the recent progress on photochemical processes on ferroelectric surfaces, the role of surface adsorbates, and imaging and switching in liquids. Beyond classical applications, probing local bias-induced transition dynamics by PFM opens the pathway to studies of the influence of a single defect on electrochemical and solid state processes, thus providing model systems for batteries, fuel cells, and supercapacitor applications.

  2. Ferroelectric control of a Mott insulator

    PubMed Central

    Yamada, Hiroyuki; Marinova, Maya; Altuntas, Philippe; Crassous, Arnaud; Bégon-Lours, Laura; Fusil, Stéphane; Jacquet, Eric; Garcia, Vincent; Bouzehouane, Karim; Gloter, Alexandre; Villegas, Javier E.; Barthélémy, Agnès; Bibes, Manuel

    2013-01-01

    The electric field control of functional properties is an important goal in oxide-based electronics. To endow devices with memory, ferroelectric gating is interesting, but usually weak compared to volatile electrolyte gating. Here, we report a very large ferroelectric field-effect in perovskite heterostructures combining the Mott insulator CaMnO3 and the ferroelectric BiFeO3 in its “supertetragonal” phase. Upon polarization reversal of the BiFeO3 gate, the CaMnO3 channel resistance shows a fourfold variation around room temperature, and a tenfold change at ~200 K. This is accompanied by a carrier density modulation exceeding one order of magnitude. We have analyzed the results for various CaMnO3 thicknesses and explain them by the electrostatic doping of the CaMnO3 layer and the presence of a fixed dipole at the CaMnO3/BiFeO3 interface. Our results suggest the relevance of ferroelectric gates to control orbital- or spin-ordered phases, ubiquitous in Mott systems, and pave the way toward efficient Mott-tronics devices. PMID:24089020

  3. High permittivity ferroelectric actuators for radar applications

    Microsoft Academic Search

    J. Ficklen; J. Weaver; C. Chen; A. A. Ayon

    2009-01-01

    We report a new method of fabricating thermal bimorph actuators utilizing high permittivity ferroelectric thin films. This device is the first known thermal cantilever actuator employing barium titanate (BaTiO3) for RF applications. Compared to electrostatic actuators, this MEMS structure is designed to handle high RF transmitted power while maintaining a high capacitance ratio due to the high permittivity of the

  4. Ferroelectric Devices Emit Charged Particles and Radiation

    NASA Technical Reports Server (NTRS)

    Bar-Cohen, Yoseph; Sherrit, Stewart; Bao, Xiaoqi; Felsteiner, Joshua; Karsik, Yakov

    2005-01-01

    Devices called solid-state ferroelectric- based sources (SSFBSs) are under development as sources of electrons, ions, ultraviolet light, and x-rays for diverse applications in characterization and processing of materials. Whereas heretofore it has been necessary to use a different device to generate each of the aforementioned species of charged particles or radiation, a single SSFBS can be configured and operated to selectively generate any of the species as needed using a single source. Relative to comparable prior sources based, variously, on field emission, thermionic emission, and gaseous discharge plasmas, SSFBSs demand less power, and are compact and lightweight. An SSFBS exploits the unique physical characteristics of a ferroelectric material in the presence of a high-frequency pulsed electric field. The basic building block of an SSFBS is a ferroelectric cathode -- a ferroelectric wafer with a solid electrode covering its rear face and a grid electrode on its front face (see figure). The application of a voltage pulse -- typically having amplitude of several kilovolts and duration of several nanoseconds -- causes dense surface plasma to form near the grid wires on the front surface.

  5. A Model for Ferroelectric Phase Shifters

    NASA Technical Reports Server (NTRS)

    Romanofsky, Robert R.; Qureshi, A. Haq

    2000-01-01

    Novel microwave phase shifters consisting of coupled microstrip lines on thin ferroelectric films have been demonstrated recently. A theoretical model useful for predicting the propagation characteristics (insertion phase shift, dielectric loss, impedance, and bandwidth) is presented here. The model is based on a variational solution for line capacitance and coupled strip transmission line theory.

  6. Uncooled infrared imaging using thin film ferroelectrics

    Microsoft Academic Search

    Charles M. Hanson; Howard R. Beratan; James F. Belcher

    2001-01-01

    Uncooled infrared imaging is growing into a large business for several companies. With hybrid barium strontium titanate (BST) ferroelectric detectors leading the way in lowering cost, the markets are exploding. Rapid advances in VOx bolometers in the last few years have improved NETDs below those achieved to date with BST, and VOx system prices have approached those for BST systems.

  7. Theory of prospective tetrahedral perovskite ferroelectrics

    E-print Network

    Roy, Anindya

    2010-01-01

    Using first-principles methods, we predict the energy landscape and ferroelectric states of double perovskites of the form AA$'$BB$'$O$_6$ in which the atoms on both the A and B sites are arranged in rock-salt order. While we are not aware of compounds that occur naturally in this structure, we argue that they might be realizable by directed synthesis. The high-symmetry structure formed by this arrangement belongs to the tetrahedral $F\\bar{4}3m$ space group. If a ferroelectric instability occurs, the energy landscape will tend to have minima with the polarization along tetrahedral directions, leading to a rhombohedral phase, or along Cartesian directions, leading to an orthorhombic phase. We find that the latter scenario applies to CaBaTiZrO$_6$ and KCaZrNbO$_6$, which are weakly ferroelectric, and the former one applies to PbSnTiZrO$_6$, which is strongly ferroelectric. The results are modeled with a fourth- or fifth-order Landau-Devonshire expansion, providing good agreement with the first-principles calcul...

  8. Ferroelectric/Optoelectronic Memory/Processor

    NASA Technical Reports Server (NTRS)

    Thakoor, Sarita; Thakoor, Anilkumar P.

    1992-01-01

    Proposed hybrid optoelectronic nonvolatile analog memory and data processor comprises planar array of microscopic photosensitive ferroelectric capacitors performing massively parallel analog computations. Processors overcome electronic crosstalk and limitations on number of input/output contacts inherent in electronic implementations of large interconnection arrays. Used in general optical computing, recognition of patterns, and artificial neural networks.

  9. Magnetically induced ferroelectricity in single crystalline Lu2CoMnO6

    NASA Astrophysics Data System (ADS)

    Chikara, Shalinee; Singleton, John; Choi, Hwan Young; Lee, Nara; Choi, Young J.; Zapf, Vivien

    2015-03-01

    We present pulsed-magnetic-field measurements on Lu2CoMnO6 single crystals. We are able to resolve electric polarization in single crystals for the first time. The bulk hysteretic magnetization couples to the electric polarization resulting in coupled, hysteretic, multiferroic behavior. The alternating S = 3 / 2 Co2+ and Mn4+ ions sit in a corner-sharing octahedral oxygen environment. The Co-Mn-Co-Mn spins order in an up-up-down-down (uudd) arrangement along the c - axis. The ferroelectricity was believed to originate from the exchange striction due to the uudd spin arrangement. However, recent dielectric measurements suggest polarization along the b - not the c - axis. Our results confirm that ferroelectricity is indeed observed along the b - axis and not along the uudd spin-ordering direction. This indicates a different origin for the multiferroic behavior. The frustrated spin system displays an incommensurate long-wavelength modulation that may play a role in inducing ferroelectricity.

  10. The conductivity mechanism and an improved C-V model of ferroelectric PZT thin film

    NASA Astrophysics Data System (ADS)

    Liang, K.; Buditama, A.; Chien, D.; Cui, J.; Cheung, P. L.; Goljahi, S.; Tolbert, S. H.; Chang, J. P.; Lynch, C. S.

    2015-05-01

    A dense, homogeneous and crack-free ferroelectric PZT thin film with <100>-preferred orientation was produced using the sol-gel method. The volume fraction ?(100) of <100>-oriented grains in the PZT film was calculated [?(100) ? 80%] from XRD of the PZT thin film and powder. The PZT thin film exhibits an open polarization vs. electric field loop and a low leakage current density from 10-8 A/cm2 to 10-7 A/cm2. The electrical conduction data were fit to a Schottky-emission model with deep traps from 100 kV/cm to 250 kV/cm. A modified capacitance model was introduced that adds electrical domain capacitance based on a metal-ferroelectric-metal (MFM) system with Schottky contacts. The model reproduces the observed non-linear capacitance vs. voltage behavior of the film.

  11. Magnetic-field-induced ferroelectric polarization reversal in magnetoelectric composites revealed by piezoresponse force microscopy

    NASA Astrophysics Data System (ADS)

    Miao, Hongchen; Zhou, Xilong; Dong, Shuxiang; Luo, Haosu; Li, Faxin

    2014-07-01

    Controlling electric polarization (or magnetization) in multiferroic materials with external magnetic fields (or electric fields) is very important for fundamental physics and spintronic devices. Although there has been some progress on magnetic-field-induced polarization reversal in single-phase multiferroics, such behavior has so far never been realized in composites. Here we show that it is possible to reverse ferroelectric polarization using magnetic fields in a bilayer Terfenol-D/PMN-33%PT composite. We realized this by ferroelectric domain imaging using piezoresponse force microscopy (PFM) under applied magnetic field loading. The internal electric field caused by the magnetoelectric (ME) effect in the PMN-PT crystal is considered as the driving force for the 180° polarization switching, and its existence is verified by switching spectroscopy PFM testing under a series of external magnetic fields. A quantitative method is further suggested to estimate the local ME coefficient based on the switching spectroscopy PFM testing results.

  12. Magnetic-field-induced ferroelectric polarization reversal in magnetoelectric composites revealed by piezoresponse force microscopy.

    PubMed

    Miao, Hongchen; Zhou, Xilong; Dong, Shuxiang; Luo, Haosu; Li, Faxin

    2014-08-01

    Controlling electric polarization (or magnetization) in multiferroic materials with external magnetic fields (or electric fields) is very important for fundamental physics and spintronic devices. Although there has been some progress on magnetic-field-induced polarization reversal in single-phase multiferroics, such behavior has so far never been realized in composites. Here we show that it is possible to reverse ferroelectric polarization using magnetic fields in a bilayer Terfenol-D/PMN-33%PT composite. We realized this by ferroelectric domain imaging using piezoresponse force microscopy (PFM) under applied magnetic field loading. The internal electric field caused by the magnetoelectric (ME) effect in the PMN-PT crystal is considered as the driving force for the 180° polarization switching, and its existence is verified by switching spectroscopy PFM testing under a series of external magnetic fields. A quantitative method is further suggested to estimate the local ME coefficient based on the switching spectroscopy PFM testing results. PMID:24953042

  13. Cold-field switching in PVDF-TrFE ferroelectric polymer nanomesas.

    PubMed

    Stolichnov, Igor; Maksymovych, Peter; Mikheev, Evgeny; Kalinin, Sergei V; Tagantsev, Alexander K; Setter, Nava

    2012-01-13

    Polarization reversal in ferroelectric nanomesas of polyvinylidene fluoride with trifluoroethylene has been probed by ultrahigh vacuum piezoresponse force microscopy in a wide temperature range from 89 to 326 K. In dramatic contrast to the macroscopic data, the piezoresponse force microscopy local switching was nonthermally activated and, at the same time, occurring at electric fields significantly lower than the intrinsic switching threshold. A "cold-field" defect-mediated extrinsic switching is shown to be an adequate scenario describing this peculiar switching behavior. The extrinsic character of the observed polarization reversal suggests that there is no fundamental bar for lowering the coercive field in ferroelectric polymer nanostructures, which is of importance for their applications in functional electronics. PMID:22324709

  14. Analysis of ferroelectric emission using initial energy effects

    SciTech Connect

    Advani, R.N.; Kreischer, K.E.; Temkin, R.J. [Massachusetts Inst. of Tech., Cambridge, MA (United States). Plasma Fusion Center

    1996-12-31

    A new theory is proposed here to explain emission from a ferroelectric cathode using a non-zero initial (kinetic) energy for the electrons emitted from the cathode. The traditional Child-Langmuir limit on current density has been exceeded by most ferroelectric limit on current density has been exceeded by most ferroelectric cathode experiments. Ferroelectric emission is inherently from electrons which have been ejected from a cathode with a non-zero initial energy. Thus one can question the applicability of the Child-Langmuir limit to explain ferroelectric emission. The new theory proposed here shows that if initial energy is taken into account then one can justify the higher current densities observed in ferroelectric cathode experiments.

  15. Molecule-displacive ferroelectricity in organic supramolecular solids

    NASA Astrophysics Data System (ADS)

    Ye, Heng-Yun; Zhang, Yi; Noro, Shin-Ichiro; Kubo, Kazuya; Yoshitake, Masashi; Liu, Zun-Qi; Cai, Hong-Ling; Fu, Da-Wei; Yoshikawa, Hirofumi; Awaga, Kunio; Xiong, Ren-Gen; Nakamura, Takayoshi

    2013-07-01

    Ferroelectricity is essential to many forms of current technology, ranging from sensors and actuators to optical or memory devices. In this circumstance, organic ferroelectrics are of particular importance because of their potential application in tomorrow's organic devices, and several pure organic ferroelectrics have been recently developed. However, some problems, such as current leakage and/or low working frequencies, make their application prospects especially for ferroelectric memory (FeRAM) not clear. Here, we describe the molecule-displacive ferroelectricity of supramolecular adducts of tartaric acid and 1,4-diazabicyclo[2.2.2]octane N,N'-dioxide. The adducts show large spontaneous polarization, high rectangularity of the ferroelectric hysteresis loops even at high operation frequency (10 kHz), and high performance in polarization switching up to 1 × 106 times without showing fatigue. It opens great perspectives in terms of applications, especially in organic FeRAM.

  16. Ferroelectric domain wall motion induced by polarized light.

    PubMed

    Rubio-Marcos, Fernando; Del Campo, Adolfo; Marchet, Pascal; Fernández, Jose F

    2015-01-01

    Ferroelectric materials exhibit spontaneous and stable polarization, which can usually be reoriented by an applied external electric field. The electrically switchable nature of this polarization is at the core of various ferroelectric devices. The motion of the associated domain walls provides the basis for ferroelectric memory, in which the storage of data bits is achieved by driving domain walls that separate regions with different polarization directions. Here we show the surprising ability to move ferroelectric domain walls of a BaTiO? single crystal by varying the polarization angle of a coherent light source. This unexpected coupling between polarized light and ferroelectric polarization modifies the stress induced in the BaTiO? at the domain wall, which is observed using in situ confocal Raman spectroscopy. This effect potentially leads to the non-contact remote control of ferroelectric domain walls by light. PMID:25779918

  17. Ferroelectric domain wall motion induced by polarized light

    PubMed Central

    Rubio-Marcos, Fernando; Del Campo, Adolfo; Marchet, Pascal; Fernández, Jose F.

    2015-01-01

    Ferroelectric materials exhibit spontaneous and stable polarization, which can usually be reoriented by an applied external electric field. The electrically switchable nature of this polarization is at the core of various ferroelectric devices. The motion of the associated domain walls provides the basis for ferroelectric memory, in which the storage of data bits is achieved by driving domain walls that separate regions with different polarization directions. Here we show the surprising ability to move ferroelectric domain walls of a BaTiO3 single crystal by varying the polarization angle of a coherent light source. This unexpected coupling between polarized light and ferroelectric polarization modifies the stress induced in the BaTiO3 at the domain wall, which is observed using in situ confocal Raman spectroscopy. This effect potentially leads to the non-contact remote control of ferroelectric domain walls by light. PMID:25779918

  18. Ferroelectric properties in PbZrO3/BaZrO3 superlattices: an ab-initio study

    NASA Astrophysics Data System (ADS)

    Al-Aqtash, Nabil; Alsaad, Ahmad; Sabirianov, Renat

    2014-03-01

    Properties of tetragonal (BaZrO3)1 /(PbZrO3)n ferroelectric superlattices with n = 1-3 are calculated from first principles within the density functional theory. We show that an antiferroelectric PbZrO3 displays ferroelectric behavior if deposited on a paraelectric substrate (BaZrO3) . We have performed total energy calculations to investigate the origins of the ferroelectricity and analyze the polarization of BaZrO3/(PbZrO3)n superlattices as function of PbZrO3 thickness. The densities of states (DOS) show that there is a strong hybridization between Zr/Pb and O atoms which play important role in stabilizing the ferroelectric ground state in the superlattices. Our calculations show that the polarization and tetragonality (c / a ratio) are reduced in the BaZrO3/PbZrO3 superlattices with respect to bulk tetragonal PbZrO3. Moreover, the tetragonality and polarizations of superlattices increase with increasing the fraction of PbZrO3 in the superlattices. The estimated polarization of the (BaZrO3)1 /(PbZrO3)1 superlattice is (38.46 ?C/cm2) , while it is (56.82 ?C/cm2) for the (BaZrO3)1 /(PbZrO3)3 superlattice and (74.22 ?C/cm2) for bulk tetragonal PbZrO3 These ferroelectric superlattices have good lattice matching with shape-memory NiMnIn Heusler alloys and could be very useful as a ferroelectric substrate to systems.

  19. Direct and simultaneous observation of ferroelectric and magnetic domains

    Microsoft Academic Search

    H. Z. Song; Y. X. Li; K. Y. Zhao; H. R. Zeng; S. X. Hui; G. R. Li; Q. R. Yin

    2009-01-01

    The ferroelectric\\/magnetic domain structure in a magnetoelectric binding BaTiO3\\/Fe81Ga19 and the ferroelectric\\/crystallographic domain structure in a magnetoelectric binding PMN-34PT\\/Mn50Ni28Ga22 were observed successfully by scanning electron acoustic microscopy (SEAM). Both the stripe ferroelectric domains in single crystals and the stripe magnetic domains in polycrystalline grains are obtained simultaneously, which exhibits that the scanning electron acoustic microscopy is a unique imaging technique.

  20. Smart ferroelectric films and fibers; applications in micromechanics

    NASA Astrophysics Data System (ADS)

    Brooks, Keith G.; Udayakumar, K. R.; Chen, Jiayu; Selvaraj, Ulagaraj; Cross, L. Eric

    Smart electroceramics, in the form of ferroelectric thin films show great potential for applications in the field of microelectromechanical systems. Ferroelectric thin films will become a key player due to their optical, mechanical, electrical, and thermal sensing with actuating capabilities. Recent results on electromechanical transduction in piezoelectric (e.g. PZT), electrostrictive (e.g. PLZT), and antiferroelectric-ferroelectric phase switching (e.g. PLZSnT) thin films and their potential applications in smart micromechanical systems are discussed. The possibility of three dimensional structures exists in the emerging technology of ferroelectric fibers. Some exciting applications for these films and fibers include microvalves, ultrasonic micromotors, microrobotic actuators, and micropumps.

  1. Improved screening ability of ferroelectric-semiconductor interface.

    PubMed

    Gureev, Maxim Y; Tagantsev, Alexander K; Setter, Nava

    2011-09-01

    Recent progress in integrating ferroelectrics directly on silicon opens the exciting possibility of implementing ferroelectric-semiconductor devices. One of the major problems for such integration is the instability of the ferroelectric state in very thin films, which is mainly controlled by the screening ability of the ferroelectric-semiconductor interface. We show here that the presence of built-in potential in the semiconductor can strongly influence the screening ability of the interface. The built-in potential depends on the electron affinities and surface states density and can be controlled by choosing the materials carefully. PMID:21937331

  2. Critical thickness for ferroelectricity in perovskite ultrathin films.

    PubMed

    Junquera, Javier; Ghosez, Philippe

    2003-04-01

    The integration of ferroelectric oxide films into microelectronic devices, combined with the size reduction constraints imposed by the semiconductor industry, have revived interest in the old question concerning the possible existence of a critical thickness for ferroelectricity. Current experimental techniques have allowed the detection of ferroelectricity in perovskite films down to a thickness of 40 A (ten unit cells), ref. 3. Recent atomistic simulations have confirmed the possibility of retaining the ferroelectric ground state at ultralow thicknesses, and suggest the absence of a critical size. Here we report first-principles calculations on a realistic ferroelectric-electrode interface. We show that, contrary to current thought, BaTiO3 thin films between two metallic SrRuO3 electrodes in short circuit lose their ferroelectric properties below a critical thickness of about six unit cells (approximately 24 A). A depolarizing electrostatic field, caused by dipoles at the ferroelectric-metal interfaces, is the reason for the disappearance of the ferroelectric instability. Our results suggest the existence of a lower limit for the thickness of useful ferroelectric layers in electronic devices. PMID:12673246

  3. Ferroelectric nanostructure having switchable multi-stable vortex states

    DOEpatents

    Naumov, Ivan I. (Fayetteville, AR); Bellaiche, Laurent M. (Fayetteville, AR); Prosandeev, Sergey A. (Fayetteville, AR); Ponomareva, Inna V. (Fayetteville, AR); Kornev, Igor A. (Fayetteville, AR)

    2009-09-22

    A ferroelectric nanostructure formed as a low dimensional nano-scale ferroelectric material having at least one vortex ring of polarization generating an ordered toroid moment switchable between multi-stable states. A stress-free ferroelectric nanodot under open-circuit-like electrical boundary conditions maintains such a vortex structure for their local dipoles when subject to a transverse inhomogeneous static electric field controlling the direction of the macroscopic toroidal moment. Stress is also capable of controlling the vortex's chirality, because of the electromechanical coupling that exists in ferroelectric nanodots.

  4. Nanomanufacturing and analysis of novel continuous ferroelectric PVDF and P(VDF-TrFE) nanofibers

    NASA Astrophysics Data System (ADS)

    Ren, Xi

    Poly(vinylidene fluoride) (PVDF) and PVDF copolymers are well known for their ferroelectric and piezoelectric properties. Currently, they are mainly used in applications in the form of films. Thin PVDF films have been shown to possess unique ferroelectric properties in the nanoscale range. However, their two-dimensional nature limits their applicability in active engineering materials and structures. One-dimensional PVDF nanofibers can be expected to combine ferroelectric behavior with enhanced mechanical properties and ultrahigh flexibility providing critical advantages for applications. In this work, novel continuous PVDF nanofibers were nanomanufactured and systematically studied for the first time. Nanofibers from PVDF and P(VDF-TrFE) copolymer with several molecular weights and co-polymer compositions were manufactured by electrospinning. The method consists of spinning polymer solutions in high electric fields. Effects of process parameters on nanofiber diameters and morphology were studied. Resulting nanofibers were characterized by FE-SEM, TEM, XRD, FTIR, DSC and TGA. Effects of annealing on copolymer nanofibers were analyzed. Nanofiber-reinforced composites were manufactured and their polarization behavior studied using a specially designed experimental device. A number of pioneering observations and discoveries were made as a result of this analysis. For example, analysis of crystalline structure of PVDF nanofibers showed that the initial a phase of the PVDF raw material was converted to beta phase during electrospinning. This result is very encouraging as the beta phase is primarily responsible for the piezo- and ferroelectric behavior of PVDF polymers. It was also shown for the first time that nanofabricated P(VDF-TrFE) nanofibers exhibited distinct Curie points and different structures than their raw materials. Annealing was shown to be an effective way to modify properties of P(VDF-TrFE) co-polymer nanofibers. Overall, the results demonstrated for the first time flexible nanomanufacturing of continuous PVDF and co-polymer nanofibers exhibiting a number of unusual ferroelectric properties. The developed continuous nanofibers can be used in a broad range of applications spanning smart and active composites, multifunctional coatings, functional textiles, ultrafast/sensitive sensors, tailorable miniature actuators, MEMS/NEMS, energy conversion devices, and many others.

  5. Polarization-induced trapped charge in ferroelectrics

    SciTech Connect

    Warren, W.L.; Pike, G.E.; Tuttle, B.A.; Dimos, D. [Sandia National Laboratories, Albuquerque, New Mexico 87185-1349 (United States)] [Sandia National Laboratories, Albuquerque, New Mexico 87185-1349 (United States)

    1997-04-01

    We have examined the nature of the defects in BaTiO{sub 3} capacitors that have been subjected to an electric field at elevated temperatures (an accelerated aging process) using thermally stimulated current (TSC) and electron paramagnetic resonance measurements. The accelerated aging stress causes the ferroelectric capacitor to exhibit a reduction in its insulating resistance and a voltage offset in its polarization-voltage hysteresis loop. Following the accelerated aging treatment, the trapped charge estimates obtained from the TSC and the hysteresis measurements (as ascertained from the voltage offset) differ significantly and are attributed to either local charge compensation or uniform charge trapping within the dielectric. We also show that some of the trapped charge in ferroelectric materials is directly associated with the net polarization. {copyright} {ital 1997 American Institute of Physics.}

  6. Thin film ferroelectric electro-optic memory

    NASA Technical Reports Server (NTRS)

    Thakoor, Sarita (Inventor); Thakoor, Anilkumar P. (Inventor)

    1993-01-01

    An electrically programmable, optically readable data or memory cell is configured from a thin film of ferroelectric material, such as PZT, sandwiched between a transparent top electrode and a bottom electrode. The output photoresponse, which may be a photocurrent or photo-emf, is a function of the product of the remanent polarization from a previously applied polarization voltage and the incident light intensity. The cell is useful for analog and digital data storage as well as opto-electric computing. The optical read operation is non-destructive of the remanent polarization. The cell provides a method for computing the product of stored data and incident optical data by applying an electrical signal to store data by polarizing the thin film ferroelectric material, and then applying an intensity modulated optical signal incident onto the thin film material to generate a photoresponse therein related to the product of the electrical and optical signals.

  7. Electrostriction in Perovskite-Type Ferroelectric Ceramics

    Microsoft Academic Search

    Naoya Uchida; Takuro Ikeda

    1967-01-01

    The electrostriction and polarization in the perovskite-type ferroelectric ceramics have been calculated in the state under the arbitrary biasing field. Domain configurations produced by 180°-reversal or 90°-rotation have been represented here by the threshold angle theta180 or theta90; that is, domains, making smaller angles than theta180 or theta90 after the switching once occurs, are completely reoriented under the given bias.

  8. Electrically induced mechanical precompression of ferroelectric plates

    DOEpatents

    Chen, Peter J. (Albuquerque, NM)

    1987-01-01

    A method of electrically inducing mechanical precompression of a ferroelectric plate covered with electrodes utilizes the change in strains of the plate as functions of applied electric field. A first field polarizes and laterally shrinks the entire plate. An outer portion of the electrodes are removed, and an opposite field partially depolarizes and expands the central portion of the plate against the shrunk outer portion.

  9. Flat panel ferroelectric electron emission display system

    DOEpatents

    Sampayan, S.E.; Orvis, W.J.; Caporaso, G.J.; Wieskamp, T.F.

    1996-04-16

    A device is disclosed which can produce a bright, raster scanned or non-raster scanned image from a flat panel. Unlike many flat panel technologies, this device does not require ambient light or auxiliary illumination for viewing the image. Rather, this device relies on electrons emitted from a ferroelectric emitter impinging on a phosphor. This device takes advantage of a new electron emitter technology which emits electrons with significant kinetic energy and beam current density. 6 figs.

  10. Flat panel ferroelectric electron emission display system

    DOEpatents

    Sampayan, Stephen E. (Manteca, CA); Orvis, William J. (Livermore, CA); Caporaso, George J. (Livermore, CA); Wieskamp, Ted F. (Livermore, CA)

    1996-01-01

    A device which can produce a bright, raster scanned or non-raster scanned image from a flat panel. Unlike many flat panel technologies, this device does not require ambient light or auxiliary illumination for viewing the image. Rather, this device relies on electrons emitted from a ferroelectric emitter impinging on a phosphor. This device takes advantage of a new electron emitter technology which emits electrons with significant kinetic energy and beam current density.

  11. Ferroelectric electrooptic ceramics with reduced scattering

    Microsoft Academic Search

    P. D. Thacher; C. E. Land

    1969-01-01

    Ferroelectric lead zirconate-titanate ceramics appear promising for use as electrically controlled retarders because both conventional electrooptic and nonvolatile incremental retardation changes can be induced in areas as small as 25 µ on a side. One particular composition, Pb0.97La0.02Zr0.65Ti0.35O3, has so far proved superior to all other rhombohedral lead zirconate-titanates when judged by either the conventional electrooptic retardation variation with applied

  12. Ferroelectric tunnel junctions with graphene electrodes

    NASA Astrophysics Data System (ADS)

    Lu, H.; Lipatov, A.; Ryu, S.; Kim, D. J.; Lee, H.; Zhuravlev, M. Y.; Eom, C. B.; Tsymbal, E. Y.; Sinitskii, A.; Gruverman, A.

    2014-11-01

    Polarization-driven resistive switching in ferroelectric tunnel junctions (FTJs)—structures composed of two electrodes separated by an ultrathin ferroelectric barrier—offers new physics and materials functionalities, as well as exciting opportunities for the next generation of non-volatile memories and logic devices. Performance of FTJs is highly sensitive to the electrical boundary conditions, which can be controlled by electrode material and/or interface engineering. Here, we demonstrate the use of graphene as electrodes in FTJs that allows control of interface properties for significant enhancement of device performance. Ferroelectric polarization stability and resistive switching are strongly affected by a molecular layer at the graphene/BaTiO3 interface. For the FTJ with the interfacial ammonia layer we find an enhanced tunnelling electroresistance (TER) effect of 6 × 105%. The obtained results demonstrate a new approach based on using graphene electrodes for interface-facilitated polarization stability and enhancement of the TER effect, which can be exploited in the FTJ-based devices.

  13. Influence of ferroelectric polarization on magnetic anisotropy

    NASA Astrophysics Data System (ADS)

    Mardana, A.; Ducharme, S.; Adenwalla, S.

    2010-03-01

    Thin film heterostructures of transition metal ferromagnets (FM) and polymer ferroelectrics (FE) are investigated to look for changes in the magnetic anisotropy of the FM layer that occur on switching the FE polarization (with an ensuing change in the electric field direction).[1] Samples of [Glass/ Pd (50 nm)/Co wedge (0.9-2.6nm)/ferroelectric P(VDF-TrFE) (53 nm)/Al (30nm)] are deposited via sputtering or evaporation for the metallic layers and via Langmuir-Schaefer deposition for the polymer ferroelectric. [2] Magnetic and FE properties have been characterized using the Magneto-Optical Kerr Effect (MOKE) and the pyroelectric effect. Polar and longitudinal MOKE loops are measured across the Co wedge for both positive and negative FE polarization and the difference in the two MOKE loops is ascribed to the changes in the magnetic anisotropy of the FM layer. [3] These changes are most apparent in the region where the Co undergoes a transition from in-plane to out-of-plane anisotropy. This research is supported by the NSF MRSEC through Grant No. DMR- 0820521 1. Chun-Gang Duan et al, Appl. Phys. Lett. 92, 122905 (2008) 2. A. V. Bune, et al, Nature (London) 391, 874 (1998) 3. P. F. Carcia, J.Appl. Phys. 63, 5066 (1988)

  14. Ferroelectric tunnel junctions with graphene electrodes.

    PubMed

    Lu, H; Lipatov, A; Ryu, S; Kim, D J; Lee, H; Zhuravlev, M Y; Eom, C B; Tsymbal, E Y; Sinitskii, A; Gruverman, A

    2014-01-01

    Polarization-driven resistive switching in ferroelectric tunnel junctions (FTJs)--structures composed of two electrodes separated by an ultrathin ferroelectric barrier--offers new physics and materials functionalities, as well as exciting opportunities for the next generation of non-volatile memories and logic devices. Performance of FTJs is highly sensitive to the electrical boundary conditions, which can be controlled by electrode material and/or interface engineering. Here, we demonstrate the use of graphene as electrodes in FTJs that allows control of interface properties for significant enhancement of device performance. Ferroelectric polarization stability and resistive switching are strongly affected by a molecular layer at the graphene/BaTiO3 interface. For the FTJ with the interfacial ammonia layer we find an enhanced tunnelling electroresistance (TER) effect of 6 × 10(5)%. The obtained results demonstrate a new approach based on using graphene electrodes for interface-facilitated polarization stability and enhancement of the TER effect, which can be exploited in the FTJ-based devices. PMID:25417720

  15. WFL: Microwave Applications of Thin Ferroelectric Films

    NASA Technical Reports Server (NTRS)

    Romanofsky, Robert

    2013-01-01

    We have developed a family of tunable microwave circuits, operating from X- through Ka-band, based on laser ablated BaxSr1-xTiO films on lanthanum aluminate and magnesium oxide substrates. Circuits include voltage controlled oscillators, filters, phase shifters and antennas. A review of the basic theory of operation of these devices will be presented along with measured performance. Emphasis has been on low-loss phase shifters to enable a new phased array architecture. The critical role of phase shifter loss and transient response in reflectarray antennas will be discussed. The Ferroelectric Reflectarray Critical Components Space Experiment was launched on the penultimate Space Shuttle, STS-134, in May of 2011. It included a bank of ferroelectric phase shifters with two different stoichiometries as well as ancillary electronics. The experiment package and status will be reported. In addition, unusual results of a Van der Pauw measurement involving a ferroelectric film grown on buffered high resisitivity silicon will be discussed.

  16. Large electrostrain in poled and aged acceptor-doped ferroelectric ceramics via reversible domain switching

    NASA Astrophysics Data System (ADS)

    Zhao, Xiaobo; Liang, Ruihong; Zhang, Wenbin; Wang, Genshui; Dong, Xianlin

    2014-12-01

    The electrostrain behavior through reversible domain switching in aged acceptor-doped ferroelectric ceramics has been widely investigated in the past decade. However, previous works were focused on unpoled ceramics, which could only utilize part of domains to exchange nonequal crystalline axis to generate strain under external electric field. In this paper, we proposed an effective method: (1) Initially, the acceptor-doped ceramics should be poled. (2) Then, the ceramics need to be aged for enough time. (3) Finally, the applied electric field should be perpendicular to the poling direction. Our method can utilize more domains to exchange nonequal crystalline axis to contribute to electrostrain in comparison with unpoled ceramics reported in the literature. According to our method, the unipolar electrostrain of 1.5 mol. % Fe-doped (Pb,Ba,Sr)(Zr,Ti)O3 ceramics in this work could reach 0.33%, which was 3.75 times larger than that of unpoled one at 3.0 kV mm-1. Meanwhile, the normalized strain d33* could reach nearly 1100 pm V-1 which was one of the highest values reported in ferroelectric ceramics. Additionally, the ceramics displayed interesting double or slim P-E (polarization-electric field) hysteresis loops at various electric fields. Our work provides a general method via reversible domain switching in aged acceptor-doped ferroelectric ceramics to obtain large electrostrain for high-displacement actuator applications.

  17. Ferroelectricity in hexagonal YFeO3 film at room temperature

    NASA Astrophysics Data System (ADS)

    Zhang, Run-Lan; Chen, Chang-Le; Zhang, Yun-Jie; Xing, Hui; Dong, Xiang-Lei; Jin, Ke-Xin

    2015-01-01

    In this paper we report the leakage current, ferroelectric and piezoelectric properties of the YFeO3 film with hexagonal structure, which was fabricated on Si(111) substrate by a simple sol-gel method. The leakage current test shows good characteristics as the leakage current density is 5.4×10?6 A/cm2 under 5 V. The dominant leakage mechanism is found to be an Ohmic behavior at low electric field and space-charge-limited conduction at high electric field region. The P–E measurements show ferroelectric hysteresis loops with small remnant polarization and coercive field at room temperature. The distinct and switchable domain structures on the nanometer scale are observed by piezoresponse force microscopy, which testifies to the ferroelectricity of the YFeO3 film further. Project supported by the National Natural Science Foundation of China (Grant Nos. 61471301, 61078057, 51202195, and 511172183), the Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20126102110045), and the NPU Foundation for Fundamental Research (Grant Nos. JC201155, JC201271, and JC20120246).

  18. A pair of dinuclear Re(I) enantiomers: synthesis, crystal structures, chiroptical and ferroelectric properties.

    PubMed

    Li, Xi-Li; Zhang, Zhiqiang; Zhang, Xue-Li; Kang, Jia-Long; Wang, Ai-Ling; Zhou, Liming; Fang, Shaoming

    2015-03-01

    The reaction of enantiomeric bis-bidentate bridging ligands (+)/(-)-2,5-bis(4,5-pinene-2-pyridyl)pyrazine (L(S)/L(R)) with [Re(CO)5Cl] yielded a pair of dinuclear Re(I) enantiomers formulated as [Re2(L(S)/L(R))(CO)6Cl2]·4CH2Cl2 (R-1 and S-1, the isomers containing the respective L(R) and L(S) ligands). They were characterized by elemental analyses, IR spectra and X-ray crystallography. Circular dichroism spectra verified their chiroptical activities and enantiomeric nature. The measurements of second harmonic generation (SHG) and ferroelectric properties showed that R-1 displays a nonlinear optical (NLO) activity and ferroelectricity with a remnant polarization (P(r)) of 1.6 ?C cm(-2) under an applied field of 7.3 kV cm(-1) at room temperature. R-1 and S-1 represent the first example of polynuclear Re(i) complexes with ferroelectric properties. Notably, the P(r) value is much larger than that of the reported mononuclear chiral Re(I) analogue. In particular, unlike mononuclear Re(i) complexes of the type [Re(CO)3(N^N)(X)] (N^N = diimine and X = halide), which usually exhibit an intense emission in the visible range, R-1 and S-1 do not show any detectable emission at any temperature range and the reason for the nonluminescence of R-1 and S-1 was further elucidated in this work. Moreover, our research results also elucidated that Re nuclearity has a great influence on not only the emitting properties but also on ferroelectric behavior. PMID:25623284

  19. Atomic-scale mapping of dipole frustration at 90° charged domain walls in ferroelectric PbTiO3 films

    PubMed Central

    Tang, Y. L.; Zhu, Y. L.; Wang, Y. J.; Wang, W. Y.; Xu, Y. B.; Ren, W. J.; Zhang, Z. D.; Ma, X. L.

    2014-01-01

    The atomic-scale structural and electric parameters of the 90° domain-walls in tetragonal ferroelectrics are of technological importance for exploring the ferroelectric switching behaviors and various domain-wall-related novel functions. We have grown epitaxial PbTiO3/SrTiO3 multilayer films in which the electric dipoles at 90° domain-walls of ferroelectric PbTiO3 are characterized by means of aberration-corrected scanning transmission electron microscopy. Besides the well-accepted head-to-tail 90° uncharged domain-walls, we have identified not only head-to-head positively charged but also tail-to-tail negatively charged domain-walls. The widths, polarization distributions, and strains across these charged domain-walls are mapped quantitatively at atomic scale, where remarkable difference between these domain-walls is presented. This study is expected to provide fundamental information for understanding numerous novel domain-wall phenomena in ferroelectrics. PMID:24534846

  20. A Model for Simulating Polarization Switching and AF-F Phase Changes in Ferroelectric Ceramics

    Microsoft Academic Search

    W. Chen; C. S. Lynch

    1998-01-01

    A computational micromechanics model for polycrystalline ferroelectric ceramics developed by Chen and Lynch (1997) is modified and applied to the simulation of ferroelectric and ferroelastic switching of the tetragonal and the rhombohedral crystal structures, and to antiferroelectric to ferroelectric phase changes. Interactions between different grains in the ceramic are considered. Two switching criteria are used, one for ferroelectric switching and

  1. Ferroelectric domain structure of Pb(Zr /sub 52/Ti /sub 48/)O/sub 3/

    SciTech Connect

    Goo, E.K.; Mishra, R.K.

    1980-08-01

    Ferroelectric domains are twins that are formed when PZT undergoes a phase transformation from a non-ferroelectric cubic phase to a ferroelectric tetragonal phase upon cooling below approx. 375/sup 0/C. The tetragonal phase is spontaneously polarized in the direction of c-axis, making each twin a ferroelectric domain.

  2. Patterned Ferroelectric Films for Tunable Microwave Devices

    NASA Technical Reports Server (NTRS)

    Miranda, Felix A.; Mueller, Carl H.

    2008-01-01

    Tunable microwave devices based on metal terminals connected by thin ferroelectric films can be made to perform better by patterning the films to include suitably dimensioned, positioned, and oriented constrictions. The patterns can be formed during fabrication by means of selective etching processes. If the width of the ferroelectric film in such a device is reduced at one or more locations, then both the microwave field and any applied DC bias (tuning) electric field become concentrated at those locations. The magnitudes of both the permittivity and the dielectric loss of a ferroelectric material are reduced by application of a DC field. Because the concentration of the DC field in the constriction(s) magnifies the permittivity- and loss-reducing effects of the applied DC voltage, the permittivity and dielectric loss in the constriction(s) are smaller in the constriction(s) than they are in the wider parts of the ferroelectric film. Furthermore, inasmuch as displacement current must flow through either the constriction(s) or the low-loss dielectric substrate, the net effect of the constriction(s) is equivalent to that of incorporating one or more low-loss, low-permittivity region(s) in series with the high-loss, high-permittivity regions. In a series circuit, the properties of the low-capacitance series element (in this case, the constriction) dominate the overall performance. Concomitantly, the capacitance between the metal terminals is reduced. By making the capacitance between the metal terminals small but tunable, a constriction increases the upper limit of the frequency range amenable to ferroelectric tuning. The present patterning concept is expected to be most advantageous for devices and circuits that must operate at frequencies from about 4 to about 60 GHz. A constriction can be designed such that the magnitude of the microwave electric field and the effective width of the region occupied by the microwave electric field become functions of the applied DC electric field, so that tunability is enhanced. It should even be possible to design the constriction to obtain a specific tuning-versus-voltage profile.

  3. High Frequency Tuneable Devices Based on Thin Ferroelectric Films

    Microsoft Academic Search

    S. Gevorgian

    Frequency and phase agile microwave technologies based on ferroelectrics are moving from laboratory demonstrators towards industrial applications. It is important, in this phase, to consider the problems which have not been addressed adequately while dealing with the materials aspects of ferroelectrics and developing laboratory demonstrators. Some of these problems are discussed in this chapter. The focus is concentrated on the

  4. New highly polar semiconductor ferroelectrics for solar energy conversion devices

    Microsoft Academic Search

    Andrew M. Rappe; Ilya Grinberg; Joseph W. Bennett

    2009-01-01

    Solar energy is a promising long-term solution for future energy requirements; however, current solar energy conversion devices are plagued by low efficiency. The use of ferroelectric ABO3 perovskite oxides is one approach for boosting conversion efficiency. Ferroelectric oxides possess spontaneous polarization and have been shown to produce a bulk photovoltaic effect, in which charged carriers, specifically electrons and holes, separate

  5. Structure of ferroelectric polarization domains written by PFM

    Microsoft Academic Search

    Rebecca Sichel; Ji Young Jo; Ryan Smith; Pice Chen; Dong Min Kim; Chang Beom Eom; Martin Holt; Kenneth Evans-Lutterodt; Nina Balke; Sergei Kalinin; Paul G. Evans

    2010-01-01

    In ferroelectric materials, polarization and atomic structure are intimately coupled. PFM is commonly used to image and write polarization domains in ferroelectric thin films, but the local structure of the resulting domains is unclear due to the uncertainty in depth sensitivity of the PFM imaging process. X-ray nanoprobe diffraction was used to simultaneously probe the structure and image polarization domains

  6. Ferroelectric thin films: Review of materials, properties, and applications

    Microsoft Academic Search

    N. Setter; D. Damjanovic; L. Eng; G. Fox; S. Gevorgian; S. Hong; A. Kingon; H. Kohlstedt; N. Y. Park; G. B. Stephenson; I. Stolitchnov; A. K. Taganstev; D. V. Taylor; T. Yamada; S. Streiffer

    2006-01-01

    An overview of the state of art in ferroelectric thin films is presented. First, we review applications: microsystems' applications, applications in high frequency electronics, and memories based on ferroelectric materials. The second section deals with materials, structure (domains, in particular), and size effects. Properties of thin films that are important for applications are then addressed: polarization reversal and properties related

  7. Ferroelectric polymer-based nanocomposites: Towards multiferroic materials

    Microsoft Academic Search

    Jennifer S. Andrew

    2008-01-01

    This dissertation describes new routes towards magnetic-ferroelectric materials, leading to new materials for multiferroic applications. Multiferroic materials exhibit both ferromagnetic and ferroelectric properties, which tend to be mutually exclusive in single-phase materials. Therefore, composite materials are the obvious approach to realizing a material with both a high electric permittivity and high magnetic permeability. In composite systems the magnetoelectric effect arises

  8. The simulation of switching in polycrystalline ferroelectric ceramics

    Microsoft Academic Search

    Stephen C. Hwang; John E. Huber; Robert M. McMeeking; Norman A. Fleck

    1998-01-01

    A polarization switching model for polycrystalline ferroelectric ceramics has been developed. It is assumed that a single ferroelectric crystallite in a ceramic, which is subjected to an electric field and\\/or a stress, undergoes a complete polarization change and a corresponding strain change if the resulting reduction in potential energy exceeds a critical value per unit volume of switching material. The

  9. Processing and characterization of high Q m ferroelectric ceramics

    Microsoft Academic Search

    C Galassi; E Roncari; C Capiani; F Craciun

    1999-01-01

    Use of ferroelectric ceramics in applications like piezoelectric transformers was made possible by the development of new materials with high electromechanical coupling coefficients and high mechanical quality factor. “Hard’’ ferroelectric ceramics of complex composition based on lead zirconate titanate with Nb, Mg, Mn and Li additives have been prepared. The perovskitic phase was produced by solid phase reaction of the

  10. A programmable ferroelectric single electron transistor Vijay Narayanan,2

    E-print Network

    Yener, Aylin

    #12;A programmable ferroelectric single electron transistor Lu Liu,1 Vijay Narayanan,2 and Suman as a suitable candidate for implementing logic with these single electron transistors (SETs).2 Due online 6 February 2013) We experimentally demonstrate a programmable ferroelectric single electron

  11. Geometric shape control of thin film ferroelectrics and resulting structures

    DOEpatents

    McKee, Rodney A. (Kingston, TN); Walker, Frederick J. (Oak Ridge, TN)

    2000-01-01

    A monolithic crystalline structure and a method of making involves a semiconductor substrate, such as silicon, and a ferroelectric film, such as BaTiO.sub.3, overlying the surface of the substrate wherein the atomic layers of the ferroelectric film directly overlie the surface of the substrate. By controlling the geometry of the ferroelectric thin film, either during build-up of the thin film or through appropriate treatment of the thin film adjacent the boundary thereof, the in-plane tensile strain within the ferroelectric film is relieved to the extent necessary to permit the ferroelectric film to be poled out-of-plane, thereby effecting in-plane switching of the polarization of the underlying substrate material. The method of the invention includes the steps involved in effecting a discontinuity of the mechanical restraint at the boundary of the ferroelectric film atop the semiconductor substrate by, for example, either removing material from a ferroelectric film which has already been built upon the substrate, building up a ferroelectric film upon the substrate in a mesa-shaped geometry or inducing the discontinuity at the boundary by ion beam deposition techniques.

  12. Future Development of Dense Ferroelectric Memories for Space Applications

    NASA Technical Reports Server (NTRS)

    Philpy, Stephen C.; Derbenwick, Gary F.

    2001-01-01

    The availability of high density, radiation tolerant, nonvolatile memories is critical for space applications. Ferroelectric memories, when fabricated with radiation hardened complementary metal oxide semiconductors (CMOS), can be manufactured and packaged to provide high density replacements for Flash memory, which is not radiation tolerant. Previous work showed ferroelectric memory cells to be resistant to single event upsets and proton irradiation, and ferroelectric storage capacitors to be resistant to neutron exposure. In addition to radiation hardness, the fast programming times, virtually unlimited endurance, and low voltage, low power operation make ferroelectric memories ideal for space missions. Previously, a commercial double level metal 64-kilobit ferroelectric memory was presented. Although the capabilities of radiation hardened wafer fabrication facilities lag behind those of the most modern commercial wafer fabrication facilities, several paths to achieving radiation tolerant, dense ferroelectric memories are emerging. Both short and long term solutions are presented in this paper. Although worldwide major semiconductor companies are introducing commercial ferroelectric memories, funding limitations must be overcome to proceed with the development of high density, radiation tolerant ferroelectric memories.

  13. Toward Ferroelectric Control of Monolayer MoS2.

    PubMed

    Nguyen, Ariana; Sharma, Pankaj; Scott, Thomas; Preciado, Edwin; Klee, Velveth; Sun, Dezheng; Lu, I-Hsi Daniel; Barroso, David; Kim, SukHyun; Shur, Vladimir Ya; Akhmatkhanov, Andrey R; Gruverman, Alexei; Bartels, Ludwig; Dowben, Peter A

    2015-05-13

    The chemical vapor deposition (CVD) of molybdenum disulfide (MoS2) single-layer films onto periodically poled lithium niobate is possible while maintaining the substrate polarization pattern. The MoS2 growth exhibits a preference for the ferroelectric domains polarized "up" with respect to the surface so that the MoS2 film may be templated by the substrate ferroelectric polarization pattern without the need for further lithography. MoS2 monolayers preserve the surface polarization of the "up" domains, while slightly quenching the surface polarization on the "down" domains as revealed by piezoresponse force microscopy. Electrical transport measurements suggest changes in the dominant carrier for CVD MoS2 under application of an external voltage, depending on the domain orientation of the ferroelectric substrate. Such sensitivity to ferroelectric substrate polarization opens the possibility for ferroelectric nonvolatile gating of transition metal dichalcogenides in scalable devices fabricated free of exfoliation and transfer. PMID:25909996

  14. Microscopic model for the ferroelectric field effect in oxide heterostructures

    SciTech Connect

    Dong, Shuai [Nanjing National Laboratory of Microstructures, Nanjing University, Nanjing; Zhang, Xiaotian [Oak Ridge National Laboratory (ORNL); Yu, Rong [Rice University; Liu, J.-M. [Nanjing National Laboratory of Microstructures, Nanjing University, Nanjing; Dagotto, Elbio R [ORNL

    2011-01-01

    A microscopic model Hamiltonian for the ferroelectric field effect is introduced for the study of oxide heterostructures with ferroelectric components. The long-range Coulomb interaction is incorporated as an electrostatic potential, solved self-consistently together with the charge distribution. A generic double-exchange system is used as the conducting channel, epitaxially attached to the ferroelectric gate. The observed ferroelectric screening effect, namely, the charge accumulation/depletion near the interface, is shown to drive interfacial phase transitions that give rise to robust magnetoelectric responses and bipolar resistive switching, in qualitative agreement with previous density functional theory calculations. The model can be easily adapted to other materials by modifying the Hamiltonian of the conducting channel, and it is useful in simulating ferroelectric field effect devices particularly those involving strongly correlated electronic components where ab initio techniques are difficult to apply.

  15. Enhanced electromechanical response of ferroelectrics due to charged domain walls.

    PubMed

    Sluka, Tomas; Tagantsev, Alexander K; Damjanovic, Dragan; Gureev, Maxim; Setter, Nava

    2012-01-01

    While commonly used piezoelectric materials contain lead, non-hazardous, high-performance piezoelectrics are yet to be discovered. Charged domain walls in ferroelectrics are considered inactive with regards to the piezoelectric response and, therefore, are largely ignored in this search. Here we demonstrate a mechanism that leads to a strong enhancement of the dielectric and piezoelectric properties in ferroelectrics with increasing density of charged domain walls. We show that an incomplete compensation of bound polarization charge at these walls creates a stable built-in depolarizing field across each domain leading to increased electromechanical response. Our model clarifies a long-standing unexplained effect of domain wall density on macroscopic properties of domain-engineered ferroelectrics. We show that non-toxic ferroelectrics like BaTiO(3) with dense patterns of charged domain walls are expected to have strongly enhanced piezoelectric properties, thus suggesting a new route to high-performance, lead-free ferroelectrics. PMID:22434191

  16. Characteristics of Radio-Frequency Circuits Utilizing Ferroelectric Capacitors

    NASA Technical Reports Server (NTRS)

    Eskridge, Michael; Gui, Xiao; MacLeod, Todd; Ho, Fat D.

    2011-01-01

    Ferroelectric capacitors, most commonly used in memory circuits and variable components, were studied in simple analog radio-frequency circuits such as the RLC resonator and Colpitts oscillator. The goal was to characterize the RF circuits in terms of frequency of oscillation, gain, etc, using ferroelectric capacitors. Frequencies of oscillation of both circuits were measured and studied a more accurate resonant frequency can be obtained using the ferroelectric capacitors. Many experiments were conducted and data collected. A model to simulate the experimental results will be developed. Discrepancies in gain and frequency in these RF circuits when conventional capacitors are replaced with ferroelectric ones were studied. These results will enable circuit designers to anticipate the effects of using ferroelectric components in their radio- frequency applications.

  17. Giant electrocaloric effect in ferroelectric nanotubes near room temperature.

    PubMed

    Liu, Man; Wang, Jie

    2015-01-01

    Ferroelectric perovskite oxides possess large electrocaloric effect, but only at high temperature, which limits their potential as next generation solid state cooling devices. Here, we demonstrate from phase field simulations that a giant adiabatic temperature change exhibits near room temperature in the strained ferroelectric PbTiO? nanotubes, which is several times in magnitude larger than that of PbTiO? thin films. Such giant adiabatic temperature change is attributed to the extrinsic contribution of unusual domain transition, which involves a dedicated interplay among the electric field, strain, temperature and polarization. Careful selection of external strain allows one to harness the extrinsic contribution to obtain large adiabatic temperature change in ferroelectric nanotubes near room temperature. Our finding provides a novel insight into the electrocaloric response of ferroelectric nanostructures and leads to a new strategy to tailor and improve the electrocaloric properties of ferroelectric materials through domain engineering. PMID:25578434

  18. Giant electrocaloric effect in ferroelectric nanotubes near room temperature

    PubMed Central

    Liu, Man; Wang, Jie

    2015-01-01

    Ferroelectric perovskite oxides possess large electrocaloric effect, but only at high temperature, which limits their potential as next generation solid state cooling devices. Here, we demonstrate from phase field simulations that a giant adiabatic temperature change exhibits near room temperature in the strained ferroelectric PbTiO3 nanotubes, which is several times in magnitude larger than that of PbTiO3 thin films. Such giant adiabatic temperature change is attributed to the extrinsic contribution of unusual domain transition, which involves a dedicated interplay among the electric field, strain, temperature and polarization. Careful selection of external strain allows one to harness the extrinsic contribution to obtain large adiabatic temperature change in ferroelectric nanotubes near room temperature. Our finding provides a novel insight into the electrocaloric response of ferroelectric nanostructures and leads to a new strategy to tailor and improve the electrocaloric properties of ferroelectric materials through domain engineering. PMID:25578434

  19. Giant electrocaloric effect in ferroelectric nanotubes near room temperature

    NASA Astrophysics Data System (ADS)

    Liu, Man; Wang, Jie

    2015-01-01

    Ferroelectric perovskite oxides possess large electrocaloric effect, but only at high temperature, which limits their potential as next generation solid state cooling devices. Here, we demonstrate from phase field simulations that a giant adiabatic temperature change exhibits near room temperature in the strained ferroelectric PbTiO3 nanotubes, which is several times in magnitude larger than that of PbTiO3 thin films. Such giant adiabatic temperature change is attributed to the extrinsic contribution of unusual domain transition, which involves a dedicated interplay among the electric field, strain, temperature and polarization. Careful selection of external strain allows one to harness the extrinsic contribution to obtain large adiabatic temperature change in ferroelectric nanotubes near room temperature. Our finding provides a novel insight into the electrocaloric response of ferroelectric nanostructures and leads to a new strategy to tailor and improve the electrocaloric properties of ferroelectric materials through domain engineering.

  20. 450 IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL, VOL. 43, NO. 3, MAY 1996 ansient Modeling of Ferroelectric Capacitors

    E-print Network

    Gulak, P. Glenn

    1996 ansient Modeling of Ferroelectric Capacitors for Nonvolatile Memories Ali Sheikholeslami and P. Glenn Gulak, Member, IEEE Abstruct- Present ferroelectric (FE) capacitor models mostly rely,corresponding to the two different polarization states of an FE capacitor. I. INTRODUCTION ERROELECTRIC (FE) capacitors

  1. A phenomenological constitutive model for ferroelastic and ferroelectric hysteresis effects in ferroelectric ceramics

    Microsoft Academic Search

    S. Klinkel

    2006-01-01

    This paper is concerned with a macroscopic constitutive law for domain switching effects, which occur in ferroelectric ceramics. The three-dimensional model is thermodynamically consistent and is determined by two scalar valued functions: the Helmholtz free energy and a switching surface. In a kinematic hardening process the movement of the center of the switching surface is controlled by internal variables. In

  2. Ferroelectric opening switches for large-scale pulsed power drivers.

    SciTech Connect

    Brennecka, Geoffrey L.; Rudys, Joseph Matthew; Reed, Kim Warren; Pena, Gary Edward; Tuttle, Bruce Andrew; Glover, Steven Frank

    2009-11-01

    Fast electrical energy storage or Voltage-Driven Technology (VDT) has dominated fast, high-voltage pulsed power systems for the past six decades. Fast magnetic energy storage or Current-Driven Technology (CDT) is characterized by 10,000 X higher energy density than VDT and has a great number of other substantial advantages, but it has all but been neglected for all of these decades. The uniform explanation for neglect of CDT technology is invariably that the industry has never been able to make an effective opening switch, which is essential for the use of CDT. Most approaches to opening switches have involved plasma of one sort or another. On a large scale, gaseous plasmas have been used as a conductor to bridge the switch electrodes that provides an opening function when the current wave front propagates through to the output end of the plasma and fully magnetizes the plasma - this is called a Plasma Opening Switch (POS). Opening can be triggered in a POS using a magnetic field to push the plasma out of the A-K gap - this is called a Magnetically Controlled Plasma Opening Switch (MCPOS). On a small scale, depletion of electron plasmas in semiconductor devices is used to affect opening switch behavior, but these devices are relatively low voltage and low current compared to the hundreds of kilo-volts and tens of kilo-amperes of interest to pulsed power. This work is an investigation into an entirely new approach to opening switch technology that utilizes new materials in new ways. The new materials are Ferroelectrics and using them as an opening switch is a stark contrast to their traditional applications in optics and transducer applications. Emphasis is on use of high performance ferroelectrics with the objective of developing an opening switch that would be suitable for large scale pulsed power applications. Over the course of exploring this new ground, we have discovered new behaviors and properties of these materials that were here to fore unknown. Some of these unexpected discoveries have lead to new research directions to address challenges.

  3. Trilinear couplings and the multi-mode anti-ferroelectric transition of PbZrO3: a first-principles investigation

    NASA Astrophysics Data System (ADS)

    Iniguez, Jorge; Stengel, Massimiliano; Prosandeev, Sergey; Bellaiche, Laurent

    2015-03-01

    We have studied ab initio the phase transition in PbZrO3, a perovskite oxide usually presented as the prototypic anti-ferroelectric material. Our work reveals the crucial role that anti-ferrodistortive modes-involving concerted rotations of the oxygen octahedra in the structure-play in the transformation, as they select the observed anti-ferroelectric phase, among competing structural variants, via a cooperative trilinear coupling. The resulting picture is that of a complex transition whose multi-mode character is essential to its very occurrence, and poses the provocative question of whether such an intricate behavior can be taken as representative of anti-ferroelectricity in perovskite oxides. Supported by MINECO-Spain and ONR.

  4. Primary and secondary pyroelectric coefficients of rhombohedral and tetragonal single-domain relaxor-PbTiO3 single crystals

    NASA Astrophysics Data System (ADS)

    Tang, Yanxue; Zhang, Shujun; Shen, Zongyang; Jiang, Wenhua; Luo, Jun; Sahul, Raffi; Shrout, Thomas R.

    2013-08-01

    The primary and secondary pyroelectric coefficients were determined for binary (1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-PT) and ternary Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PIN-PMN-PT) relaxor-PT single crystals. The secondary pyroelectric coefficients were calculated from the thermodynamic inter-relationship between the piezoelectric, elastic, and thermal expansion coefficients. Poling along [111] and [001] directions resulted in single-domain state of "1R" and "1T" and a macroscopic symmetry of 3m and 4mm for rhombohedral (x = 0.28) and tetragonal (x = 0.42) crystals, respectively, enabling relatively large values of pyroelectric coefficients p ? 5.7 × 10-4 C/m2 K. The calculated results show that the secondary pyroelectric coefficients are in the range of (-0.62 ˜ -1.06) × 10-4 C/m2 K for rhombohedral crystals and (0.70 ˜ 1.14) × 10-4 C/m2 K for tetragonal crystals, significantly lower than that of primary pyroelectric coefficients, which is important for thermal directional and imaging applications. In contrast, high d15 piezoelectric coefficients (>2000 pC/N), together with zero pyroelectric coefficients in thickness shear crystals, also makes them promising candidates for piezoelectric sensors where thermal noise is undesirable.

  5. Ferroelectric domain wall pinning at a bicrystal grain boundary in bismuth ferrite

    SciTech Connect

    Rodriguez, Brian J [ORNL; Zhao, T. [University of California, Berkeley; Chu, Y. H. [University of California, Berkeley; Ramesh, R. [University of California, Berkeley; Kalinin, Sergei V [ORNL

    2008-01-01

    The ferroelectric polarization switching behavior at the 24 bicrystal grain boundary (GB) in a multiferroic BiFeO3 epitaxial film is studied using piezoresponse force microscopy (PFM). The PFM amplitudes across positively and negatively poled GB regions suggest the presence of a frozen polarization component at the interface. The switching experiments demonstrate that the GB attracts the domain wall and acts as a pinning center. The PFM results are compared with conductive atomic force microscopy images, which suggest domain-wall pinning at the GB can be partially attributed to increased conductance at the GB.

  6. Four-state ferroelectric spin-valve

    PubMed Central

    Quindeau, Andy; Fina, Ignasi; Marti, Xavi; Apachitei, Geanina; Ferrer, Pilar; Nicklin, Chris; Pippel, Eckhard; Hesse, Dietrich; Alexe, Marin

    2015-01-01

    Spin-valves had empowered the giant magnetoresistance (GMR) devices to have memory. The insertion of thin antiferromagnetic (AFM) films allowed two stable magnetic field-induced switchable resistance states persisting in remanence. In this letter, we show that, without the deliberate introduction of such an AFM layer, this functionality is transferred to multiferroic tunnel junctions (MFTJ) allowing us to create a four-state resistive memory device. We observed that the ferroelectric/ferromagnetic interface plays a crucial role in the stabilization of the exchange bias, which ultimately leads to four robust electro tunnel electro resistance (TER) and tunnel magneto resistance (TMR) states in the junction. PMID:25961513

  7. Four-state ferroelectric spin-valve.

    PubMed

    Quindeau, Andy; Fina, Ignasi; Marti, Xavi; Apachitei, Geanina; Ferrer, Pilar; Nicklin, Chris; Pippel, Eckhard; Hesse, Dietrich; Alexe, Marin

    2015-01-01

    Spin-valves had empowered the giant magnetoresistance (GMR) devices to have memory. The insertion of thin antiferromagnetic (AFM) films allowed two stable magnetic field-induced switchable resistance states persisting in remanence. In this letter, we show that, without the deliberate introduction of such an AFM layer, this functionality is transferred to multiferroic tunnel junctions (MFTJ) allowing us to create a four-state resistive memory device. We observed that the ferroelectric/ferromagnetic interface plays a crucial role in the stabilization of the exchange bias, which ultimately leads to four robust electro tunnel electro resistance (TER) and tunnel magneto resistance (TMR) states in the junction. PMID:25961513

  8. Chemical route to ferroelectric thin film capacitors

    Microsoft Academic Search

    J. P Mercurio; J. H Yi; P Thomas; M Manier

    1999-01-01

    For the first time the fabrication of ferroelectric SrBi2(Ta,Nb)2O9 thin film capacitors with RuO2 electrodes is conducted using a full chemical route. SrBi2(Ta,Nb)2O9 sols were obtained from niobium and tantalum ethoxides mixed with bismuth and strontium 2-ethylhexanoates. RuO2 sols were prepared by dissolving an aqueous solution of ruthenium nitrosylnitrate into 2-methoxyethanol. Capacitors were fabricated by spin coating the precursor solutions

  9. A lead-halide perovskite molecular ferroelectric semiconductor

    PubMed Central

    Liao, Wei-Qiang; Zhang, Yi; Hu, Chun-Li; Mao, Jiang-Gao; Ye, Heng-Yun; Li, Peng-Fei; Huang, Songping D.; Xiong, Ren-Gen

    2015-01-01

    Inorganic semiconductor ferroelectrics such as BiFeO3 have shown great potential in photovoltaic and other applications. Currently, semiconducting properties and the corresponding application in optoelectronic devices of hybrid organo-plumbate or stannate are a hot topic of academic research; more and more of such hybrids have been synthesized. Structurally, these hybrids are suitable for exploration of ferroelectricity. Therefore, the design of molecular ferroelectric semiconductors based on these hybrids provides a possibility to obtain new or high-performance semiconductor ferroelectrics. Here we investigated Pb-layered perovskites, and found the layer perovskite (benzylammonium)2PbCl4 is ferroelectric with semiconducting behaviours. It has a larger ferroelectric spontaneous polarization Ps=13??C?cm?2 and a higher Curie temperature Tc=438?K with a band gap of 3.65?eV. This finding throws light on the new properties of the hybrid organo-plumbate or stannate compounds and provides a new way to develop new semiconductor ferroelectrics. PMID:26021758

  10. A lead-halide perovskite molecular ferroelectric semiconductor.

    PubMed

    Liao, Wei-Qiang; Zhang, Yi; Hu, Chun-Li; Mao, Jiang-Gao; Ye, Heng-Yun; Li, Peng-Fei; Huang, Songping D; Xiong, Ren-Gen

    2015-01-01

    Inorganic semiconductor ferroelectrics such as BiFeO3 have shown great potential in photovoltaic and other applications. Currently, semiconducting properties and the corresponding application in optoelectronic devices of hybrid organo-plumbate or stannate are a hot topic of academic research; more and more of such hybrids have been synthesized. Structurally, these hybrids are suitable for exploration of ferroelectricity. Therefore, the design of molecular ferroelectric semiconductors based on these hybrids provides a possibility to obtain new or high-performance semiconductor ferroelectrics. Here we investigated Pb-layered perovskites, and found the layer perovskite (benzylammonium)2PbCl4 is ferroelectric with semiconducting behaviours. It has a larger ferroelectric spontaneous polarization Ps=13??C?cm(-2) and a higher Curie temperature Tc=438?K with a band gap of 3.65?eV. This finding throws light on the new properties of the hybrid organo-plumbate or stannate compounds and provides a new way to develop new semiconductor ferroelectrics. PMID:26021758

  11. Design of a Multi-Level/Analog Ferroelectric Memory Device

    NASA Technical Reports Server (NTRS)

    MacLeod, Todd C.; Phillips, Thomas A.; Ho, Fat D.

    2006-01-01

    Increasing the memory density and utilizing the dove1 characteristics of ferroelectric devices is important in making ferroelectric memory devices more desirable to the consumer. This paper describes a design that allows multiple levels to be stored in a ferroelectric based memory cell. It can be used to store multiple bits or analog values in a high speed nonvolatile memory. The design utilizes the hysteresis characteristic of ferroelectric transistors to store an analog value in the memory cell. The design also compensates for the decay of the polarization of the ferroelectric material over time. This is done by utilizing a pair of ferroelectric transistors to store the data. One transistor is used as a reference to determine the amount of decay that has occurred since the pair was programmed. The second transistor stores the analog value as a polarization value between zero and saturated. The design allows digital data to be stored as multiple bits in each memory cell. The number of bits per cell that can be stored will vary with the decay rate of the ferroelectric transistors and the repeatability of polarization between transistors. It is predicted that each memory cell may be able to store 8 bits or more. The design is based on data taken from actual ferroelectric transistors. Although the circuit has not been fabricated, a prototype circuit is now under construction. The design of this circuit is different than multi-level FLASH or silicon transistor circuits. The differences between these types of circuits are described in this paper. This memory design will be useful because it allows higher memory density, compensates for the environmental and ferroelectric aging processes, allows analog values to be directly stored in memory, compensates for the thermal and radiation environments associated with space operations, and relies only on existing technologies.

  12. Effect of local A-site strain on dipole stability in A6GaNb9O30 (A = Ba, Sr, Ca) tetragonal tungsten bronze relaxor dielectrics.

    PubMed

    Miller, Andrew J; Rotaru, Andrei; Arnold, Donna C; Morrison, Finlay D

    2015-06-21

    A series of isovalently A-site substituted relaxor dielectric tetragonal tungsten bronzes of general formula Ba6-x-ySrxCayGaNb9O30 were investigated. The long-range (average) crystal structure as determined by conventional diffraction techniques varies monotonically according to Vegard's law. The dielectric properties, however, do not display a similar, simple "average size" dependence and instead show a dependence on the statistical size variance, i.e. size mismatch, of the A-cation. The difficulties in Vogel-Fulcher analysis of relative permittivity and the complementary approach of using dielectric loss data fitted to Jonscher's empirical universal dielectric relaxation model is discussed. PMID:25687218

  13. Dynamical magnetoelectric effects associated with ferroelectric domain walls

    NASA Astrophysics Data System (ADS)

    Prosandeev, Sergey; Malashevich, Andrei; Raevski, Igor P.; Bellaiche, L.

    2015-03-01

    Molecular dynamics simulations using a first-principles-derived effective Hamiltonian are conducted on lead zirconium titanate ultrathin films possessing nanoscale ferroelectric domains and experiencing a GHz electric field. Pulses of magnetization are predicted to occur in this system when sudden changes occur in the morphology of these nanodomains. A simple equation relating the magnetization and product between the electric polarization and its time derivative is found to reproduce and explain these magnetization pulses as well as previously observed magnetoelectric effects in moving ferroelectric domain walls and phase boundaries in ferroelectrics and magnetoelectrics.

  14. Strain-induced ferroelectricity in simple rocksalt binary oxides.

    PubMed

    Bousquet, Eric; Spaldin, Nicola A; Ghosez, Philippe

    2010-01-22

    Using first-principles density functional calculations, we show that ferroelectricity can be induced in simple alkaline-earth-metal binary oxides such as barium oxide (BaO) using appropriate epitaxial strains. Going beyond the fundamental discovery, we highlight that the functional properties (polarization, dielectric constant, and piezoelectric response) of such strained binary oxides are comparable in magnitude to those of typical ferroelectric perovskite oxides, making them of direct interest for applications. Finally, we show that magnetic binary oxides such as EuO, with the same rocksalt structure, behave similarly to the alkaline-earth-metal oxides, suggesting a route to new multiferroics combining ferroelectric and magnetic properties. PMID:20366683

  15. Induced magneto-electric coupling in ferroelectric/ferromagnetic heterostructures

    NASA Astrophysics Data System (ADS)

    Carvell, Jeffrey; Cheng, Ruihua; Dowben, P. A.; Yang, Q.

    2013-08-01

    Using an external magnetic field, we have demonstrated room temperature control of the electric polarization of a ferroelectric polymer, polyvinylidene fluoride (PVDF), in an artificial multiferroic structure. For ferroelectric PVDF polymer thin films in an iron-PVDF-iron heterostructure, both the ferroelectric coercivity and polarization display a hysteresis dependence on the external magnetic field. We also find that the thickness of the PVDF layer has an effect on the magnetoelectric coupling in our samples. We observe a giant magnetoelectric coupling with values as large as 3700 V/cm Oe to 41700 V/cm Oe.

  16. Ferroelectric based catalysis: Switchable surface chemistry

    NASA Astrophysics Data System (ADS)

    Kakekhani, Arvin; Ismail-Beigi, Sohrab

    2015-03-01

    We describe a new class of catalysts that uses an epitaxial monolayer of a transition metal oxide on a ferroelectric substrate. The ferroelectric polarization switches the surface chemistry between strongly adsorptive and strongly desorptive regimes, circumventing difficulties encountered on non-switchable catalytic surfaces where the Sabatier principle dictates a moderate surface-molecule interaction strength. This method is general and can, in principle, be applied to many reactions, and for each case the choice of the transition oxide monolayer can be optimized. Here, as a specific example, we show how simultaneous NOx direct decomposition (into N2 and O2) and CO oxidation can be achieved efficiently on CrO2 terminated PbTiO3, while circumventing oxygen (and sulfur) poisoning issues. One should note that NOx direct decomposition has been an open challenge in automotive emission control industry. Our method can expand the range of catalytically active elements to those which are not conventionally considered for catalysis and which are more economical, e.g., Cr (for NOx direct decomposition and CO oxidation) instead of canonical precious metal catalysts. Primary support from Toyota Motor Engineering and Manufacturing, North America, Inc.

  17. Integrated non-planar ferroelectric nanostructures

    NASA Astrophysics Data System (ADS)

    Nonnenmann, Stephen Sommers

    Ferroelectrics (FEs) exhibit stable spontaneous polarization states in the absence of an applied electric field, analogous to other ferroic systems such as ferromagnetics and ferroelastics. Incomplete screening of surface charges along the FE-electrode interface creates a potential gradient across the FE layer. This yields a depolarizing field which greatly suppresses polarization, particularily in systems approaching finite sizes, where surface and interface effects exhibit far more influence than in the bulk. Identifying mechanisms for reducing the detrimental effects of the depolarizing field and maintaining FE stability in finite dimensions remains the largest obstacle in FEs realizing their potential as next generation devices such as electrocaloric coolers, actuators, sensors, photovoltaics, and non-volatile memory elements. This thesis aims to develop a reproducible, versatile synthetic approach towards cylindrical conductive core-ferroelectric perovskite oxide shell nanostructures. The inherent finite curvature produces surface-tension based stresses which may be used to nonlinearily couple to charge, thus mitigating the destabilizing effects of the depolarizing field. This study will show that FE stability is enhanced in curved nanostructures as compared to their planar counterparts. Piezoresponse force microscopy, a modified scan probe technique, will be used to elucidate these effects via imaging and static hysteresis collection. The improved FE stability enables the demonstration of a single, integrated FE field effect transistor test structure, showing nanoscale integration of a FE layer in direct contact with silicon, a notable challenge in developing semiconductor industrial applications.

  18. Ferroelectric polarization and domain walls in orthorhombic (K1-xNax)NbO3 lead-free ferroelectric ceramics

    NASA Astrophysics Data System (ADS)

    Lu, Ning; Yu, Rong; Cheng, Zhiying; Dai, Yejing; Zhang, Xiaowen; Zhu, Jing

    2010-05-01

    Combining aberration-corrected high-resolution transmission electron microscopy with first-principles calculations, we have investigated the ferroelectric polarization and the atomic structures of 60°/120° domain walls in orthorhombic (K0.46Na0.54)NbO3 lead-free ferroelectric ceramics. The projections of cation-oxygen dipoles across the 60°/120° domain walls were determined using the recently developed negative spherical-aberration imaging technique. The measured ferroelectric distortion matched well with that obtained from first-principles calculations. The width across the wall was measured to be ˜1.1 nm.

  19. Unit-cell scale mapping of ferroelectricity and tetragonality in epitaxial ultrathin ferroelectric films

    Microsoft Academic Search

    Chun-Lin Jia; Valanoor Nagarajan; Jia-Qing He; Lothar Houben; Tong Zhao; Ramamoorthy Ramesh; Knut Urban; Rainer Waser

    2007-01-01

    Typically, polarization and strain in ferroelectric materials are coupled, leading to the generally accepted direct relation between polarization and unit-cell tetragonality. Here, by means of high-resolution transmission electron microscopy we map, on the unit-cell scale, the degree of tetragonality and the displacements of cations away from the centrosymmetry positions in an ultrathin epitaxial PbZr0.2Ti0.8O3 film on a SrRuO3 electrode layer

  20. Ferroelectrics, 419:18, 2011 Copyright Taylor & Francis Group, LLC

    E-print Network

    Schmidt, Wolf Gero

    (0001) ionization energy has been determined by UV-photoelectron emission microscopy (PEEM) [13] and its the surface properties. However, to have control over the ferroelectric domains, a deep knowledge