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1

Electromechanical behavior of relaxor ferroelectric crystals  

NASA Astrophysics Data System (ADS)

Relaxor ferroelectric PZN-xPT and PMN-xPT single crystals exhibit extraordinary electromechanical properties. They are under development for applications in sensors, actuators and transducers. The polarization switching and phase transition behavior of PZN-4.5%PT and PMN-32%PT single crystals under external loading has been investigated. Experimental investigation elucidates the polarization switching and phase transition behavior of relaxor ferroelectric crystals at different orientation cuts under combined temperature, electric field and stress loading. These crystals exhibit strong orientation dependence of electromechanical properties, and the applied fields all affect the poling and phase states of the crystals. Based on experimental investigation, crystal variant modeling was developed to compute the piezoelectric properties of multi-domain crystals at different orientation cuts from a set of properties for the single domain. Thermodynamics and work-energy analysis of field induced phase transitions in these single crystals sheds light on the phase transition mechanism of ferroelectric crystals. Fracture behavior of relaxor single crystals under non-uniform electric fields at a partial electrode edge has also been measured and analyzed.

Liu, Tieqi

2

Relaxor ferroelectric behavior of poly(vinylidene fluoride-trifluorethylene) copolymer modified by low energy irradiation  

SciTech Connect

We report a relaxorlike modification in the ferroelectric poly(vinylidene fluoride-trifluorethylene) copolymer using ultraviolet (UV) irradiation. This behavior is clearly demonstrated by dielectric measurements. Besides the relaxor feature, the ferroelectric character of the material is retained, also exhibiting Curie transition at barely diminished temperatures. UV-Vis absorption measurements suggests that the UV radiation induces conjugated C=C bonds in the copolymer chains. The coexistence of both relaxor and ferroelectric behavior, the lack of chain cross-linking, and a weak reducing in the crystallinity suggest that the UV-induced defects are not sufficient to completely break up the polarization domains.

Faria, Luiz O.; Welter, Cezar; Moreira, Roberto L. [Centro de Desenvolvimento da Tecnologia Nuclear, C.P. 941, Belo Horizonte, 30123-970, Minas Gerais (Madagascar) (Brazil); Departamento de Fisica, UFMG, C.P. 702, Belo Horizonte, 30123-970 Minas Gerais (Madagascar) (Brazil)

2006-05-08

3

Local symmetry approach to relaxor ferroelectrics  

NASA Astrophysics Data System (ADS)

We propose a theoretical framework based on local gauge symmetries and develop a first-principles-derived effective Hamiltonian to study relaxor ferroelectrics. The approach is applied to PLZT relaxor and i) qualitatively reproduces many of its generic features, such as all the characteristic temperatures inherent to relaxor ferroelectrics and their dependence on the La concentration, ii) yields a rich variety of ferroelectric phases, depending on La content, iii) reveals the existence of non-perfectly ordered regions even in the ferroelectric state, iv) allows, for the first time, to compute the critical exponent ? in a relaxor ferroelectric, and v) clearly elucidates how the relaxor behavior, such as a diffusive phase transition, arises due to the disorder-induced non-trivial interplay between local and global scales.

Nahas, Y.; Kornev, I.

2013-08-01

4

Crossover from glassy to ferroelectric polarization behavior under a dc bias electric field in relaxor ferroelectrics  

NASA Astrophysics Data System (ADS)

The remanent dielectric polarization Pr(T) , as estimated from zero-field heated (ZFH) pyroelectric current between 10 and 295 K, was studied in the pyrochlore relaxor ferroelectric Cd2Nb2O7 on approach to the field-induced ferroelectric (FE) state both from an ergodic relaxor state (ERS) and a nonergodic glassy relaxor state (NERS). The measurements were done after field cooling (PrFC) and zero-field cooling (PrZFC) a relaxor system to a given temperature far below the freezing temperature Tf , removing (applying) the bias, and subsequent ZFC (FC) to 10 K. PrFC(T) and PrZFC(T) behave differently both in a weak and rather high dc bias electric field, which evidences the different character of the NERS developing in these regimes and the different predisposition of the NERS to a formation of the long-range FE ordering. The large splitting between PrFC and PrZFC confirms the glassy nature of the NERS. For NERS-to-FE crossover, the critical field EcrNERS?EcrERS , while at EcrERSrelaxors is prearranged during ZFC and FC through Tf .

Kolpakova, N. N.; Czarnecki, P.; Nawrocik, W.; Shcheglov, M. P.; Syrnikov, P. P.; Szczepa?ska, L.

2005-07-01

5

Divide line between relaxor, diffused ferroelectric, ferroelectric and dielectric  

Microsoft Academic Search

The dielectric spectroscopic studies of relaxor ferroelectric Ba(Ti0.70Sn0.30)O3 (BTS30), diffused ferroelectric Ba(Ti0.70Sn0.20)O3 (BTS20), classical ferroelectric BaTiO3 (BT0), and normal dielectric Ba(Fe0.50Ta0.50O3) (BFT) were carried out in the temperatures ?100 K–650 K, and frequencies ?100 Hz–1 MHz, which showed relaxor behavior at 130 K with typical 30 K frequency dispersion, perfect diffused ferroelectric character at 190 K, classical ferroelectric, and dielectric relaxation at 450 K–550 K respectively. A

I. Rivera; Ashok Kumar; N. Ortega; R. S. Katiyar; Sergey Lushnikov

2009-01-01

6

Relaxor behavior of ferroelectric Ca0.22Sr0.12Ba0.66Nb2O6  

NASA Astrophysics Data System (ADS)

The relaxor behavior of tetragonal tungsten bronze uniaxial relaxor ferroelectric calcium strontium barium niobate (Ca0.22Sr0.12Ba0.66Nb2O6 or CSBN-22) single crystal was studied by measuring elastic constants and thermal expansion with the aid of resonant ultrasound spectroscopy and dilatometry, respectively, in the temperature range 300 K-1503 K. Thermal expansion yields evidence of the Burns temperature TB and the intermediate characteristic temperature T*, which was also supported by the temperature evolutions of the elastic constants cij. CSBN-22 was found to be ~2%-3% elastically stiffer than CBN-28. The presented results open the perspective to understand the relaxor behavior of CSBN.

Shekhar Pandey, Chandra; Schreuer, Jürgen; Burianek, Manfred; Mühlberg, Manfred

2013-01-01

7

Relaxor ferroelectric behavior of BaMnO3 (2H) at room temperature  

NASA Astrophysics Data System (ADS)

Geometrically frustrated hexagonal BaMnO3 (2H) is an interesting material due to the presence of more than one ferroic order parameters. Although the material is well known, still there exists confusion on the crystal structure of this material at room temperature and its ferroelectric properties have not been explored. Here, we report noncentrosymmetric crystal structure and ferroelectric properties of BaMnO3 (2H) at room temperature. The dielectric diffusivity calculated from modified Curie-Weiss laws and non linear Vogel-Fulcher fittings implies weak relaxor characteristic of BaMnO3 (2H). The ferroelectric properties arise due to off centering of Mn4+ ion in unit cell and weak relaxor properties are attributed to the presence of a smaller amount of Mn3+ cations which creates disorder in 2H-BaMnO3.

Satapathy, S.; Singh, M. K.; Pandit, Pragya; Gupta, P. K.

2012-01-01

8

Multiscale dynamics in relaxor ferroelectrics  

SciTech Connect

The multiscale dynamics of complex oxides is illustrated by pairs of mechanical resonances that are excited in the relaxor ferroelectric K1 xLixTaO3 (KLT). These macroscopic resonances are shown to originate in the collective dynamics of piezoelectric polar nanodomains (PND) interacting with the surrounding lattice. Their characteristic Fano lineshapes and rapid evolution with temperature reveal the coherent interplay between the piezoelectric oscillations and orientational relaxations of the PNDs at higher temperature and the contribution of heterophase oscillations near the phase transition. A theoretical model is presented, that describes the evolution of the resonances over the entire temperature range. Similar resonances are observed in other relaxors and must therefore be a common characteristics of these systems.

Toulouse, J. [Lehigh University, Bethlehem, PA] [Lehigh University, Bethlehem, PA; Cai, L [Lehigh University, Bethlehem, PA] [Lehigh University, Bethlehem, PA; Pattnaik, R. K. [Lehigh University, Bethlehem, PA] [Lehigh University, Bethlehem, PA; Boatner, Lynn A [ORNL] [ORNL

2014-01-01

9

Diffuse phase transition in BaTi1-xSnxO3 ceramics: An intermediate state between ferroelectric and relaxor behavior  

NASA Astrophysics Data System (ADS)

Dielectric relaxation and polar structures of BaTi1-xSnxO3 ceramics, x=0.10-0.20, are investigated by means of dielectric spectroscopy and piezoresponse force microscopy. A transition regime between ``normal'' ferroelectric and relaxor behaviors is encountered. In the compositions with x=0.10, a complex domain pattern confirming the ferroelectric state is observed. Strong dielectric relaxation around Tm is attributed to domain wall motion. On the other hand, the dielectric spectra in the sample with x=0.20 are very similar to those observed in relaxor ferroelectrics. Analysis of the relaxation spectra at the intermediate concentration, x=0.15, reveals both domain wall response and an additional contribution related to mesoscale polar structures. The appearance of relaxor behavior in BaTi1-xSnxO3 is discussed within the framework of the random field model.

Shvartsman, V. V.; Kleemann, W.; Dec, J.; Xu, Z. K.; Lu, S. G.

2006-06-01

10

Transition dynamics in relaxor ferroelectrics  

Microsoft Academic Search

Raman scattering was used to study two model relaxor ferroelectrics, namely PbMg1\\/3 Nb2\\/3O3(PMN) with the 1:2 stoichiometric composition of Mg and Nb ions in the oxygen octahedrons and PbSc1\\/2Ta1\\/2O3 (PST) with the 1:1 stoichiometric composition of Sc and Ta ions. In spite of a different stoichiometric ratio the Raman spectra of both materials are consistent with the Fm3m space symmetry

I. G. Siny; R. S. Katiyar

1998-01-01

11

Origin of diffuse scattering in relaxor ferroelectrics  

NASA Astrophysics Data System (ADS)

High-pressure and variable temperature single crystal synchrotron X-ray measurements combined with first-principles based molecular dynamics simulations study diffuse scattering in the relaxor ferroelectric system PSN (PbSc1/2Nb1/2O3). Constant temperature experiments show pressure induced transition to the relaxor phase at different temperatures characterized by butterfly and rod shaped diffuse scattering around the h00 and hh0 Bragg spots, respectively. The simulations [1] reproduce the observed diffuse scattering features as well as their pressure-temperature behavior, and show that they arise from polarization correlations between chemically-ordered regions, which in previous simulations were shown to behave as polar nanoregions. Simulations also exhibit radial diffuse scattering (elongated towards and away from Q=(000)), that persists even in the paraelectric phase, consistent with previous neutron experiments on (PbMg1/3Nb2/3O3) (PMN). DFPT calculations to elucidate origin of Raman peaks in the relaxor phase will also be presented. [4pt] [1] P. Ganesh, E. Cockayne, M. Ahart, R. E. Cohen, B. Burton, Russell J. Hemley, Yang Ren, Wange Yang and Z.-G. Ye, Phys. Rev. B 81, 144102 (2010)

Ganesh, P.

2011-03-01

12

Relaxor Ferroelectrics for Electrostrictive Transducers: Electrostrictive Strain/Dielectric Properties of Relaxor Ferroelectrics.  

National Technical Information Service (NTIS)

The electrostrictive actuator and nonresonant transducer capabilities of relaxor ferroelectrics have been of practical interest for the last decade. Displacement transducers from materials which have large elecrostrictive effects are advantageous for seve...

1991-01-01

13

Role of template layer on microstructure, phase formation and polarization behavior of ferroelectric relaxor thin films  

NASA Astrophysics Data System (ADS)

(1-x)Pb(Mg1/3Nb2/3)O3-(x)PbTiO3 (PMNPT) a relaxor ferroelectric has gained attention due to its interesting physical properties both in the bulk and thin film forms from a technological and fundamental point of view. The PMNPT solid solution at the morphotropic phase boundary composition has superior properties and is potentially used as an electrostrictive actuator, sensor, and in MEMS applications. Deposition of phase pure PMNPT thin films on bare platinized silicon wafers has been an impossible task so far. In this study the role of the LSCO template on the phase formation and the influence of platinum surface on the same have been studied. It was observed that formation of hillocks in Pt coated silicon wafers is associated with an ATG type of instability while roughening through strain relaxation. The hillocks formation was observed only on the troughs of the strain waves on the surface of Pt. The nucleation and growth of the PMNPT films were analyzed using AFM studies and the nucleation nucleates only at the tips of the hillocks and grows along the same direction with a new nucleus adjacent to the first one. A wavy pattern of PMNPT nuclei was observed and later the lateral growth of the islands takes place to cover the surface and minimizes the roughness to 2 nm. Hence, a template layer with a minimum of 40 nm is required to have a complete coverage with a roughness of less than 2 nm. The chemical states of the PMNPT films grown with and without the template layer were analyzed using x-ray photoelectron spectrum. The XPS spectrum of PMNPT deposited on a Pt surface exhibited a reduced oxidation state of niobium ions and a metallic state of Pb at the initial stage of the growth, which effectively destabilizes the perovskite phase of PMNPT in which the charge states and the ordering of Nb and Mg are more crucial to have a stable perovskite structure.

Ranjith, R.; Chaudhuri, Ayan Roy; Krupanidhi, S. B.; Victor, P.

2007-05-01

14

Relaxor or classical ferroelectric behavior in A site substituted perovskite type Ba1-x (Sm0.5Na0.5)x TiO3  

NASA Astrophysics Data System (ADS)

New ferroelectric ceramics of ABO3 perovskite type were synthesized in the Ba1-x (Sm0.5Na0.5)x TiO3 system by solid state reaction technique. The effect of the replacement of barium by samarium and sodium in the A cationic site on structural and physical properties was investigated. These compounds crystallize with tetragonal or cubic symmetry. The material is classical ferroelectric for 0 x ? 0.1 and 0.5 ? x ? 0.6, and present a relaxor behavior for 0.2 ? x ? 0.4. The dielectric behavior depends upon the cationic disorder in the A site and the cell size. Small rate substitution allows a ferroelectric-paraelectric transition. For higher rate of substitution the possible random position of the Sm-Na cations brings to a relaxor sate and when the substitution rate x becomes higher than 0.5, the material comes back to a ferroelectric state due to the reduced cell size. Some of these new compositions are of interest for applications due to their physical properties and environmentally friendly character.

Abdelmoula, N.; Chaabane, H.; Khemakhem, H.; von der Mühll, R.; Simon, A.

2006-04-01

15

Field-Induced Percolation of Polar Nanoregions in Relaxor Ferroelectrics  

NASA Astrophysics Data System (ADS)

A first-principles-based effective Hamiltonian is used to investigate low-temperature properties of Ba(Zr,Ti)O3 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, Eth, 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 Eth 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.

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

2013-05-01

16

Aging and Barkhausen noise in the relaxor ferroelectrics  

NASA Astrophysics Data System (ADS)

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).

Chao, Lambert Key

17

Induction of relaxor state in ordinary ferroelectrics by isovalent ion substitution: A pretransitional martensitic texture case  

NASA Astrophysics Data System (ADS)

The understanding of the structural origin of relaxor ferroelectrics has been doubtlessly a long-standing puzzle in the field of ferroelectricity. Thus, motivated by the interest in improving the comprehension of this important issue, it a framework is proposed for explaining the origin of the relaxor state in ordinary ferroelectrics induced via the isovalent-ion substitution. Based on the martensitic transformation concepts, it is proposed that the continuous addition of isovalent ions in a so-called normal ferroelectric decreases considerably the elastic strain energy. This results in a gradual transformation of ferroelectric domain patterns from a micrometer polydomain structure (twins), through single domains, to nanometer-polar-“tweed” structures with glasslike behavior, that are, in turn, strongly driven by point defects and surface effects. The electrical interaction between these weakly coupled polar-tweed structures leads to a wide spectrum of relaxation times, thus resulting in a dielectric relaxation process, the signature of relaxor ferroelectrics.

Lente, M. H.; Moreira, E. N.; Garcia, D.; Eiras, J. A.; Neves, P. P.; Doriguetto, A. C.; Mastelaro, V. R.; Mascarenhas, Y. P.

2006-02-01

18

Molecular dynamics computational studies of relaxor ferroelectric behavior in Pb(Mg1/4Ti1/4Nb1/2)O3 (PMN-PT)  

NASA Astrophysics Data System (ADS)

Relaxor ferroelectrics are of fundamental scientific interest and are also used in a variety of applications, such as piezoelectric transducers and capacitors. They exhibit permittivity peaks that are broad with respect to both temperature and frequency. We have developed a bond-valence model for Pb(Mg1/4Ti1/4Nb1/2)O3 (PMN-PT) and performed atomistic bond-valence molecular dynamics (BVMD) simulations of PMN-PT. We have studied relaxor behavior at a range of temperatures, in order to analyze polar nanoregion dynamics and relaxation lifetimes. We find that even for a fairly small simulation size of 6x6x6 supercell (1080 atoms), the system exhibits frequency dispersion. We present the results of 6x6 x6, 8x8x8 and 10x10x10 supercell BVMD simulations, analyze the pair distribution function of the PMN-PT and elucidate the local chemical origin of relaxor behavior.

Takenaka, Hiroyuki; Grinberg, Ilya; Rappe, Andrew

2009-03-01

19

Phonon localization drives polar nanoregions in a relaxor ferroelectric.  

PubMed

Relaxor ferroelectrics exemplify a class of functional materials where interplay between disorder and phase instability results in inhomogeneous nanoregions. Although known for about 30 years, there is no definitive explanation for polar nanoregions (PNRs). Here we show that ferroelectric phonon localization drives PNRs in relaxor ferroelectric PMN-30%PT using neutron scattering. At the frequency of a preexisting resonance mode, nanoregions of standing ferroelectric phonons develop with a coherence length equal to one wavelength and the PNR size. Anderson localization of ferroelectric phonons by resonance modes explains our observations and, with nonlinear slowing, the PNRs and relaxor properties. Phonon localization at additional resonances near the zone edges explains competing antiferroelectric distortions known to occur at the zone edges. Our results indicate the size and shape of PNRs that are not dictated by complex structural details, as commonly assumed, but by phonon resonance wave vectors. This discovery could guide the design of next generation relaxor ferroelectrics. PMID:24718289

Manley, M E; Lynn, J W; Abernathy, D L; Specht, E D; Delaire, O; Bishop, A R; Sahul, R; Budai, J D

2014-01-01

20

Light scattering spectroscopy of relaxor ferroelectrics  

Microsoft Academic Search

Raman scattering was studied in model relaxor ferroelectrics PbSc1\\/2Ta1\\/2O3PST) and PbMg1\\/3Nb2\\/3O3(PMN) (both single crystals) and in related low-permittivity materials SrAl1\\/2Ta1\\/2O3 (SAT), SrAl1\\/2Nb1\\/2O3 (SAN) and BaMg1\\/3Ta2\\/3O3 (BMT) (all ceramics). A comparative analysis of the Raman spectra suggests that these complex perovskites consist of nanoscale clusters with the 1:1 B-site order, irrespective of (1:1 or 1:2) B cations stoichiometric composition. This result

I. G. Siny; S. G. Lushnikov; R. S. Katiyar

1999-01-01

21

Mesoscopic model of a system possessing both relaxor ferroelectric and relaxor ferromagnetic properties  

NASA Astrophysics Data System (ADS)

A pseudospin model of a multiferroic system which exhibits both relaxor ferroelectric and relaxor ferromagnetic behavior is presented. The electric and magnetic degrees of freedom associated with the simultaneous presence of polar nanoregions and magnetic nanoregions are described by two sets of pseudospin variables, which satisfy separate spherical conditions. The spin-glass-like random interactions within each subset are assumed to be infinitely ranged. In addition, the polar nanoregions are subject to random electric fields. By introducing strain modulation of the corresponding random interaction parameters, a fourth-order interaction between polar and magnetic degrees of freedom is derived whose strength can be estimated from the phenomenological electrostriction and magnetostriction coefficients. Dynamic dielectric susceptibility in the presence of a static magnetic field H is calculated from the Langevin equations of motion. The value of the critical magnetic field at which long-range ferroelectric order appears is determined. By considering the corresponding free-energy density functional, the local electric field inside the polar nanoregions is derived and it is shown that the mechanism of growth and percolation of polar nanoregions is also affected by the magnetic field. Thus the Vogel-Fulcher relaxation time is predicted to diverge on a line of percolation critical points in the H,T plane, in agreement with recent experiments.

Pirc, R.; Blinc, R.; Scott, J. F.

2009-06-01

22

Discontinuous domain wall motion in the relaxor ferroelectric Sr0.61Ba0.39Nb2O6  

Microsoft Academic Search

The relaxor ferroelectric strontium-barium-niobate is characterized by internal random electric fields at the origin of its relaxor behavior. The electric poling cycle induces an irreversible transition into a ferroelectric state accompanied by a large flow of mobile charges. Bipolar fields applied in the poled state yield no acoustic emissions for half-cycles in poling direction. In contrast, discontinuous domain wall movement

D. C. Lupascu; T. Granzow; Th. Woike

2004-01-01

23

Behavior of optical phonons near the diffuse phase transition in relaxor ferroelectric Pb Mg1\\/3 Ta2\\/3 O3  

Microsoft Academic Search

Raman scattering in relaxor ferroelectric PbMg1\\/3Ta2\\/3O3 (PMT) was investigated in the single-crystalline form in the temperature range of 20-295K . An anomalous temperature dependence of the integrated intensity and the Raman line contours were found at the diffuse phase transition. A correlation between the anomalies in the integrated intensities and the dispersion of the dielectric response was observed. The distortions

S. G. Lushnikov; S. N. Gvasaliya; R. S. Katiyar

2004-01-01

24

Anisotropic Local Correlations and Dynamics in a Relaxor Ferroelectric  

NASA Astrophysics Data System (ADS)

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.

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

2013-04-01

25

Relaxor or classical ferroelectric behavior in A-site substituted perovskite type Ba 1- x(Sm 0.5Na 0.5) xTiO 3  

NASA Astrophysics Data System (ADS)

New ferroelectric ceramics of ABO 3 perovskite type were synthetized in the Ba 1- x(Sm 0.5Na 0.5) xTiO 3 system by solid state reaction technique. The effect of the replacement of barium by samarium and sodium in the A cationic site on structural and physical properties was investigated. These compounds crystallize with tetragonal or cubic symmetry. The material is classical ferroelectric for 0?x?0.1 and x?0.5, and present a relaxor behavior for 0.2?x<0.4. The dielectric behavior depends upon the cationic disorder in the A-site and the cell size. Small rate substitution allows a ferroelectric-paraelectric transition. For higher rate of substitution the possible random position of the Sm-Na cations brings to a relaxor state and when the substitution rate x becomes higher than 0.5, the material comes back to a ferroelectric state due to the reduced cell size. Some of these new compositions are of interest for applications due to their physical properties and environmentally friendly character.

Abdelmoula, N.; Chaabane, H.; Khemakhem, H.; Von der Mühll, R.; Simon, A.

2006-08-01

26

Multinuclear NMR studies of relaxor ferroelectrics  

NASA Astrophysics Data System (ADS)

Multinuclear NMR of 93Nb, 45Sc, and 207Pb has been carried out to study the structure, disorder, and dynamics of a series of important solid solutions: perovskite relaxor ferroelectric materials (1-x) Pb(Mg1/3Nb 2/3)O3-x Pb(Sc1/2Nb1/2)O 3 (PMN-PSN). 93Nb NMR investigations of the local structure and cation order/disorder are presented as a function of PSN concentration, x. The superb fidelity and accuracy of 3QMAS allows us to make clear and consistent assignments of spectral intensities to the 28 possible nearest B-site neighbor (nBn) configurations, (NMg, NSc, NNb), where each number ranges from 0 to 6 and their sum is 6. For most of the 28 possible nBn configurations, isotropic chemical shifts and quadrupole product constants have been extracted from the data. The seven configurations with only larger cations, Mg 2+ and Sc3+ (and no Nb5+) are assigned to the seven observed narrow peaks, whose deconvoluted intensities facilitate quantitative evaluation of, and differentiation between, different models of B-site (chemical) disorder. The "completely random" model is ruled out and the "random site" model is shown to be in qualitative agreement with the NMR experiments. To obtain quantitative agreement with observed NMR intensities, the random site model is slightly modified by including unlike-pair interaction energies. To date, 45Sc studies have not been as fruitful as 93Nb NMR because the resolution is lower in the 45Sc spectra. The lower resolution of 45Sc spectra is due to a smaller span of isotropic chemical shift (40 ppm for 45Sc vs. 82 ppm for 93Nb) and to the lack of a fortuitous mechanism that simplifies the 93Nb spectra; for 93Nb the overlap of the isotropic chemical shifts of 6-Sc and 6-Nb configurations results in the alignment of all the 28 configurations along only seven quadrupole distribution axes. Finally we present variable temperature 207Pb static, MAS, and 2D-PASS NMR studies. Strong linear correlations between isotropic and anisotropic chemical shifts show that Pb-O bonds vary from more ionic to more covalent environments. Distributions of Pb-O bond lengthes are also quantitatively described. Such distributions are used to examine two competing models of Pb displacements; the shell model and the unique direction model. Only the latter model is able to reproduce the observed Pb-O distance distribution.

Zhou, Donghua

27

Relaxor Pb(Mg(1/3)Nb(2/3))O3: a ferroelectric with multiple inhomogeneities.  

PubMed

Despite intensive studies on Pb(Mg(1/3)Nb(2/3))O(3) (PMN) relaxor, understanding the exact nature of its giant dielectric response and of its physical ground state is a fundamental issue that has remained unresolved for decades. Here, we report a comprehensive study of PMN relaxor crystal, and show that (i) its anomalous dielectric behavior in a broad temperature range results from the reorientation of polarization in the crystal, and (ii) the PMN relaxor is essentially a nanosized ferroelectric material with multiscale inhomogeneities of domain structure in addition to the well-known inhomogeneities of chemical composition and local symmetry. Such inhomogeneities are believed to play a crucial role in producing the huge and enigmatic physical effects in relaxor system, and may be used to design other new systems with giant effects such as a relaxor system. PMID:20366012

Fu, Desheng; Taniguchi, Hiroki; Itoh, Mitsuru; Koshihara, Shin-ya; Yamamoto, N; Mori, Shigeo

2009-11-13

28

Origin of the enhanced flexoelectricity of relaxor ferroelectrics  

NASA Astrophysics Data System (ADS)

We have measured the bending-induced polarization of Pb(Mg1/3Nb2/3)O3-PbTiO3 single crystals with compositions at the relaxor-ferroelectric phase boundary. The crystals display flexocoupling coefficients f > 100 V, an order of magnitude bigger than the theoretical upper limit set by the theories of Kogan and Tagantsev. This enhancement persists in the paraphase up to a temperature T* = 500 ± 25 K that coincides with the onset of anelastic softening in the crystals; above T*, the true (lattice-based) flexocoupling coefficient is measured as f13 ? 10 V for both compositions. Cross-correlation between flexoelectric, dielectric, and elastic properties indicates that the enhancement of bending-induced polarization of relaxor ferroelectrics is not caused by intrinsically giant flexoelectricity but by the reorientation of polar nanodomains that are ferroelastically active below T*.

Narvaez, Jackeline; Catalan, Gustau

2014-04-01

29

Recent progress in relaxor ferroelectrics with perovskite structure  

Microsoft Academic Search

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

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

2006-01-01

30

Properties of epitaxial films made of relaxor ferroelectrics.  

PubMed

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

Prosandeev, S; Wang, Dawei; Bellaiche, L

2013-12-13

31

Properties of Epitaxial Films Made of Relaxor Ferroelectrics  

NASA Astrophysics Data System (ADS)

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.

Prosandeev, S.; Wang, Dawei; Bellaiche, L.

2013-12-01

32

Electric-field dependent freezing in relaxor ferroelectrics  

NASA Astrophysics Data System (ADS)

The concept of polar nanoregions (PNRs) in relaxor ferroelectrics has recently been discussed in several numerical and theoretical studies for the special case of barium zirconate-titanate Ba(ZrxTi1-x)O3 (BZT). Here we present a semiphenomenological model of relaxation in BZT and related systems in order to show that the correlation radius of a PNR is determined by the condition that the surrounding medium undergoes a local phase transformation into a correlated polar state. The model describes the growth and percolation of the PNRs on lowering the temperature or under the application of an electric field, leading to a generalized Vogel-Fulcher-type dielectric relaxation time. It is suggested that the above condition might be applied to discriminate between the relaxor state and the analogous dipolar glass state.

Pirc, R.; Kutnjak, Z.

2014-05-01

33

Aging and Noise in the Relaxor Ferroelectrics PLZT and PMN/PT  

NASA Astrophysics Data System (ADS)

Aging and noise experiments in the relaxor ferroelectric regime of relaxors can probe the nature of the underlying disorder among the ferroelectric nanodomains and the equilibration processes involved. We present data for the relaxors PLZT (9/65/35) and (PMN)_0.7PT_0.3 (PMN/PT). PLZT aging behavior indicates the existence of two regimes with apparently different aging mechanisms: a high-T regime near the susceptibility peak (with anomalously large aging) and a low-T regime. Aging (reduction of the susceptibility \\chi (t)) is power-law in both regimes. The low-T regime exhibits spin-glass-like behavior (such as aging close to scaling with ? tw and aging behavior after temporary interruption by the application of a DC bias) similar to that seen in PMN(Colla phet al.), Phys. Rev. Lett. 85, 3033 (2000)., whereas the high-T regime does not. PMN/PT exhibits logarithmic aging with no aging memory after cooling to lower temperatures. Preliminary data on PMN/PT indicate the presence of Barkhausen noise.

Chao, Lambert K.; Colla, Eugene V.; Weissman, M. B.

2001-03-01

34

Stability of perovskite-type clusters in melts for relaxor ferroelectric crystal growth  

Microsoft Academic Search

Relaxor ferroelectric single crystals with perovskite structure were novel materials which might revolutionize some applications\\u000a in medical ultrasonic imaging, telecommunication and ultrasonic devices. But during crystal growth and melt solidification,\\u000a pyrochlore-type phase presented now and then, which reduced the integrality and properties of ferroelectric single crystals.\\u000a This work dealt with the stability of perovskite-type clusters in melts for relaxor ferroelectric

Zengzhe Xi; Wei Long; Jiangnan Liu; Peng Liu; Zhenrong Li; Xi Yao

2009-01-01

35

Relaxor-ferroelectric superlattices: high energy density capacitors  

NASA Astrophysics Data System (ADS)

We report the breakdown electric field and energy density of laser ablated BaTiO3/Ba(1-x)SrxTiO3 (x = 0.7) (BT/BST) relaxor-ferroelectric superlattices (SLs) grown on (100) MgO single crystal substrates. The dielectric constant shows a frequency dispersion below the dielectric maximum temperature (Tm) with a merger above Tm behaving similarly to relaxors. It also follows the basic criteria of relaxor ferroelectrics such as low dielectric loss over wide temperature and frequency, and 50 K shift in Tm with change in probe frequency; the loss peaks follow a similar trend to the dielectric constant except that they increase with increase in frequency (˜40 kHz), and satisfy the nonlinear Vogel-Fulcher relation. Well-saturated ferroelectric hysteresis and 50-80% dielectric saturation are observed under high electric field (˜1.65 MV cm-1). The superlattices demonstrate an ‘in-built’ field in as grown samples at low probe frequency (<1 kHz), whereas it becomes more symmetric and centered with increase in the probe frequency system (>1 kHz) which rules out the effect of any space charge and interfacial polarization. The P-E loops show around 12.24 J cm-3 energy density within the experimental limit, but extrapolation of this data suggests that the potential energy density could reach 46 J cm-3. The current density versus applied electric field indicates an exceptionally high breakdown field (5.8-6.0 MV cm-1) and low current density (˜10-25 mA cm-2) near the breakdown voltage. The current-voltage characteristics reveal that the space charge limited conduction mechanism prevails at very high voltage.

Ortega, N.; Kumar, A.; Scott, J. F.; Chrisey, Douglas B.; Tomazawa, M.; Kumari, Shalini; Diestra, D. G. B.; Katiyar, R. S.

2012-11-01

36

Relaxor based ferroelectric single crystals for electro-mechanical actuators  

Microsoft Academic Search

The piezoelectric properties of relaxor based ferroelectric single crystals, such as Pb(Zn1\\/3Nb2\\/3)O3?PbTiO3 (PZN-PT) and Pb(Mg1\\/3Nb2\\/3)O3?PbTiO3 (PMN-PT) were investigated for electromechanical actuators. In contrast to polycrystalline materials such as Pb(Zr,Ti)O3 (PZTs), morphotropic phase boundary (MPB) compositions were not essential for high piezoelectric strain. Piezoelectric coefficients\\u000a (d33’s ) >2200 pC\\/N and subsequent strain levels up to >0.5% with minimal hysteresis were observed.

S.-E. Park; Thomas R. Shrout

1997-01-01

37

Temperature, frequency and bias-field co-dependence of the electrostrictive relaxor ferroelectric lead magnesium niobate-lead titinate  

NASA Astrophysics Data System (ADS)

Fundamental to the design of intelligent material systems and structures are the realization of attributes of the constitutive materials - the sensors and actuators - and the ability to model the characteristics of these transducers. In this paper, electromechanical behaviors of the electrostrictive relaxor ferroelectric lead magnesium niobate-lead titinate (PMN-PT) are phenomenologically modeled. The dependencies of PMN-PT electromechanical transduction on temperature and frequency, characteristics of relaxor ferroelectrics, and on applied direct-current electric field, an attribute of electrostrictors which enables tunable transduction sensitivities, are modeled with respect to electrical, sensing, and actuation properties. The objective for this research is to mathematically represent the behaviors of PMN-PT sensors and actuators with respect to temperature, frequency, and bias field for practical application to mechanical and control design.

Namboodri, Chet G., Jr.

1993-04-01

38

Characterization of lead-based relaxor ferroelectric crystals by acoustic emission  

NASA Astrophysics Data System (ADS)

The acoustic emission (AE) method is presented as a useful complementary tool for nondestructive characterization of selective relaxor ferroelectrics. Combined measurements of the dielectric permittivity and AE activity as a function of temperature and externally applied electric fields have been carried out using Pb(Mg 1/3Nb 2/3)O 3-33%PbTiO 3 (PMN-0.33PT) single crystals and Pb(Sc 0.5Ta 0.5)O 3 (PST) single crystals. Anomalous behavior in the electric field dependencies of the characteristic temperatures, T m (diffuse permittivity maximum in PMN-PT) and T n (formation of incommensurate antiferroelectric domains in PST), and the associated AE intensities has been observed. Both T m and T n exhibit minima coinciding with the AE activities maxima at critical values of the applied dc electric fields, 0.5 and 0.13 kV respectively. These phenomena are discussed mainly in terms of the interaction of the external field with the random electric fields originating from the polar nanoregions in relaxor ferroelectrics.

Roth, M.; Dul'kin, E.; Mojaev, E.; Tseitlin, M.

2011-12-01

39

Interfacial reaction of Ag\\/Pd metals with Pb-based relaxor ferroelectrics including additives  

Microsoft Academic Search

In order to effectively control the interfacial reactions during co-firing a multilayer ceramic device (MLCD), different effects of silver\\/palladium on Pb-based relaxor ferroelectric ceramics were investigated by means of a series of powder X-ray diffraction (XRD) spectra and chemical reaction thermodynamics. It is found that the reaction kinetics of palladium and Pb-based relaxor ceramics lies in the activity of palladium

Ruzhong Zuo; Longtu Li; Ningxin Zhang; Zhilun Gui

2001-01-01

40

Relaxor ferroelectricity and magnetoelectric coupling in ZnO-Co nanocomposite thin films: beyond multiferroic composites.  

PubMed

ZnO-Co nanocomposite thin films are synthesized by combination of pulsed laser deposition of ZnO and Co ion implantation. Both superparamagnetism and relaxor ferroelectricity as well as magnetoelectric coupling in the nanocomposites have been demonstrated. The unexpected relaxor ferroelectricity is believed to be the result of the local lattice distortion induced by the incorporation of the Co nanoparticles. Magnetoelectric coupling can be attributed to the interaction between the electric dipole moments and the magnetic moments, which are both induced by the incorporation of Co. The introduced ZnO-Co nanocomposite thin films are different from conventional strain-mediated multiferroic composites. PMID:24598535

Li, D Y; Zeng, Y J; Batuk, D; Pereira, L M C; Ye, Z Z; Fleischmann, C; Menghini, M; Nikitenko, S; Hadermann, J; Temst, K; Vantomme, A; Van Bael, M J; Locquet, J-P; Van Haesendonck, C

2014-04-01

41

Elastic softening and polarization memory in PZN-PT relaxor ferroelectrics  

NASA Astrophysics Data System (ADS)

Substantial elastic softening in the cubic phase of PZN-PT relaxor ferroelectric crystals is observed as a large hysteresis between the RUS frequencies from poled and depoled crystals. This is due to static switchable polar nanoregions (PNR) at T*, well below the conventional Burns temperature but ˜50 K above the ferroelectric transition. Elastic softening due to polarization of the PNR shows polarization memory through two phase transitions and is greater than the softening associated with polarization of the ferroelectric phases. This emphasizes that PNR dominate the material properties at all temperatures below T*.

Farnsworth, S. M.; Kisi, E. H.; Carpenter, M. A.

2011-11-01

42

Evaluation of field enforced antiferroelectric to ferroelectric phase transition dielectrics and relaxor ferroelectrics for pulse discharge capacitors  

SciTech Connect

Discharge capacitors were designed based on materials with antiferroelectric (AFE) to ferroelectric (FE) field enforced transitions that had 10 times the capacitance of relaxor ferroelectric or state of the art BaTiO{sub 3} materials in the voltage range of interest. Nonlinear RLC circuit analysis was used to show that the AFE to FE materials have potentially more than 2 times the peak discharge current density capability of the BaTiO{sub 3} or lead magnesium niobate (PMN) based relaxor materials. Both lead lanthanum zirconium tin titanate (PLZST) AFE to FE field enforced phase transition materials and PMN based relaxor materials were fabricated and characterized for Sandia`s pulse discharge capacitor applications. An outstanding feature of the PLZST materials is that there are high field regimes where the dielectric constant increases substantially, by a factor of 20 or more, with applied field. Specifically, these materials have a low field dielectric constant of 1,000, but an effective dielectric constant of 23,000 in the electric field range corresponding to the FE to AFE transition during discharge. Lead magnesium niobate (PMN) based relaxor materials were also investigated in this project because of their high dielectric constants. While the PMN based ceramics had a low field dielectric constant of 25,000, at a field corresponding to half the charging voltage, approximately 13 kV/cm, the dielectric constant decreases to approximately 7,500.

Hoover, B.D.; Tuttle, B.A.; Olson, W.R.; Goy, D.M.; Brooks, R.A.; King, C.F.

1997-09-01

43

Resonant ultrasonic spectroscopy of KTa1-xNbxO3 ferroelectric relaxor crystals  

SciTech Connect

The influence of the development of a ferroelectric state on the elastic properties of KTa1-xNbxO3 relaxor crystals is explored. The high sensitivity of all elements of the elastic stiffness tensor to the polar distortions and their reorientational dynamics is, however, individual for each particular element: c11 and c44 are pimarily influenced by the reorientational motion of these distortions between neighboring (111) directions; the c12 mostly depends on the reorientations between cubic face diagonal (111) directions. Consequently, the temperature behavior of c12 demonstrates different dependence on the Nb concentration than that of c11 and c44. While in the 1.2% Nb crystal all three elastic constants clearly show their softening with the appearance of the dynamic polar distortions; in the 16% crystal this effect is strong for c11 and c44, but negligible for c12. The curves of slowness and Young's modulus within (100) crystallographic plane are presented. The linear compressibility modulus is estimated. The value of the Debye temperature is estimated to be approximately 592 K.

Svitelskiy, O. [Florida State University; Headley, S. [Florida State University; Suslov, A. V. [Florida State University; Migliori, A. [Los Alamos National Laboratory (LANL); Yong, G. [Towson University, Maryland; Boatner, Lynn A [ORNL

2008-01-01

44

Diffuse scattering in relaxor ferroelectrics: true three-dimensional mapping, experimental artefacts and modelling.  

PubMed

The available body of experimental data in terms of the relaxor-specific component of diffuse scattering is critically analysed and a collection of related models is reviewed; the sources of experimental artefacts and consequent failures of modelling efforts are enumerated. Furthermore, it is shown that the widely used concept of polar nanoregions as individual static entities is incompatible with the experimental diffuse scattering results. Based on the synchrotron diffuse scattering three-dimensional data set taken for the prototypical ferroelectric relaxor lead magnesium niobate-lead titanate (PMN-PT), a new parameterization of diffuse scattering in relaxors is presented and a simple phenomenological picture is proposed to explain the unusual properties of the relaxor behaviour. The model assumes a specific slowly changing displacement pattern, which is indirectly controlled by the low-energy acoustic phonons of the system. The model provides a qualitative but rather detailed explanation of temperature, pressure and electric-field dependence of diffuse neutron and X-ray scattering, as well as of the existence of a hierarchy in the relaxation times of these materials. PMID:22186288

Bosak, A; Chernyshov, D; Vakhrushev, Sergey; Krisch, M

2012-01-01

45

Relaxor features in ferroelectric superlattices: A Maxwell-Wagner approach  

NASA Astrophysics Data System (ADS)

A Maxwell-Wagner series capacitor model is proposed to explain anomalous dielectric properties of ferroelectric superlattices. The results of the model show that a superlattice consisting of normal ferroelectric layers separated by low-resistivity interfacial regions can account for most experimental results reported to date, namely: dielectric enhancement for certain stacking periodicities, giant permittivities, and temperature migration of dielectric maxima as a function of frequency. The predictions of the model are discussed and compared to our own experimental results from thin film superlattice capacitors made by pulsed-laser deposition.

Catalan, G.; O'Neill, D.; Bowman, R. M.; Gregg, J. M.

2000-11-01

46

Frustration of ferroelectricity in epitaxial film of relaxor ferroelectric PbSc1/2Nb1/2O3.  

PubMed

Relaxor-to-ferroelectric transformations induced by varying electric fields and temperatures are studied experimentally in acube-on-cubetype epitaxial PbSc1/2Nb1/2O3 film grown on La1/2Sr1/2CoO3/MgO(001). Dielectric response, quasi-static and dynamic polarization, and dynamic current-voltage characteristics evidence the absence of spontaneous relaxor-to-ferroelectric transition. The electricfield-induced transformation from a glass-like relaxor state to a new dynamic polar state is detected at low temperatures below 100?K only. The frustration of ferroelectricity is discussed in relation to orientational anisotropy of the dipolar system in the epitaxial (001) film. PMID:25030065

Tyunina, M; Pintilie, I; Iuga, A; Stratulat, M S; Pintilie, L

2014-08-13

47

A high-k ferroelectric relaxor terpolymer as a gate dielectric for orgnaic thin film transistors  

SciTech Connect

Poly(vinylidenefluoride-trifluoroethylene-chlorofluoroethylene) (P(VDF-TrFE-CFE)) is a ferroelectric terpolymer relaxor with a static dielectric constant of 50, which was developed using defect modification to eliminate remnant polarization in the normal ferroelectric PVDF. In this work, this solution processable terpolymer was used as the gate insulator in bottom gated organic thin-film transistors with a pentacene semiconductor layer. Due to the high dielectric constant of P(VDF-TrFE- CFE), a large capacitive coupling between the gate and channel can be achieved which causes a high charge concentration at the interface of the semiconductor and dielectric layers. In this device, an on/ off ratio of 104 and a low minimum operation gate voltage (5-10 V) were attained

Wu, Shan [Pennsylvania State University; Shao, Ming [ORNL; Burlingame, Quinn [Pennsylvania State University; Chen, Xiangzhong [Penn state university; Lin, Minren [Pennsylvania State University; Xiao, Kai [ORNL; Zhang, Qiming [Pennsylvania State University

2013-01-01

48

Investigation of a relationship between dielectric peak diffuseness and elastic modulus variations in a ferroelectric relaxor  

NASA Astrophysics Data System (ADS)

The dependence with temperature of elastic modulus of relaxor ferroelectric ceramics is modeled with a Landau-Devonshire-type cluster theory. The effective elastic modulus obtained from experimental data of ultrasonic longitudinal velocity in PCT and PLZT ferroelectric ceramics are compared with the proposed model. This comparison shows that the model is able to reproduce the dependence with temperature of elastic modulus c very well. We obtained that as impurity concentration increases in both families, the diffuseness of the transition shows important variations, but the strengths of the couplings between the polarization and the strain remain almost unchanged. In contrast, other models assigned a change in the strengths of the couplings between the polarization and the strain to explain the diffuse transition in these compounds.

Sarasúa, L. G.; Moreno, A.; Favre, S.; Eiras, J. A.

2014-03-01

49

Phonon anomalies induced by polar nano-regions in a relaxor ferroelectric  

NASA Astrophysics Data System (ADS)

Inelastic neutron scattering was used to measure both acoustic and optic phonons polarized along (110) (T2 mode) in the relaxor ferroelectric compound PZN-4.5PT. In the low temperature rhombohedral phase, a single domain state was achieved by cooling the single crystal sample under an external electric field of 2 kV/cm along the [111] direction. Phonon measurements were performed near the (2,2,0) and (2,-2,0) Bragg peaks. We have found that the TA2 phonon couples closely to the diffuse scattering, which arises from polar nano-regions in the system. With the redistribution of diffuse scattering under the external field (see Ref. 1), a clear hardening of TA2 mode was observed near the (2,2,0) Bragg peak, while the TA2 mode near (2,-2,0) Bragg peak softens significantly and becomes over-damped. Our results indicate local inhomogeneities such as the PNR can have direct and significant effects on the lattice dynamics and stability of the whole system. Ref. 1: ``Electric-field-induced redistribution of polar nano-regions in a relaxor ferroelectric'', Guangyong Xu, Z. Zhong, Y. Bing, Z.-G. Ye, and G. Shirane, Nature Materials 5, 134, (2006).

Xu, Guangyong; Wen, Jinsheng; Stock, Chris; Gehring, Peter

2007-03-01

50

Ferroelectric relaxor behaviour and impedance spectroscopy of Bi2O3-doped barium zirconium titanate ceramics  

NASA Astrophysics Data System (ADS)

Bi2O3-doped barium zirconate titanate ceramics, Ba1-xBix(Zr0.05Ti0.95)O3, have been prepared by the conventional solid-state reaction method. The ferroelectric relaxor behaviour and dielectric properties have been investigated in detail. By XRD analysis, it is suggested that up to x = 0.04, Bi3+ substitutes A-site ion, and thereafter with higher Bi3+ content, it enters the B-site sub lattice. Substitution of Bi3+ ions induces ferroelectric relaxor behaviour and the degree of relaxation behaviour increases with bismuth concentration. The remanent polarization and strain behaviour show a slight increase with the substitution level. The degree of hysteresis (strain versus electric field) also reduces from 21.4% to 4.6% with bismuth substitution. Impedance measurements were made on the prepared sample over a wide range of temperatures (300-723 K) and frequencies (40 Hz-1 MHz), which show the presence of both bulk and grain boundary effects in the material. The bulk and grain boundary conductivities determined from impedance study indicate the Arrhenius-type thermally activated process. Impedance spectroscopy is shown to be an efficient method capable of detecting the contributions of the resistances of grains and grain boundaries to the complex impedance of a ceramic system, accurately estimating its electrical conductivity as well as its corresponding activation energies and drawing conclusions on its structural properties.

Mahajan, Sandeep; Thakur, O P; Bhattacharya, D K; Sreenivas, K

2009-03-01

51

Effect of sintering temperature on the phase transition and dielectrical response in the relaxor-ferroelectric-system 0.5PZN-0.5PZT  

NASA Astrophysics Data System (ADS)

Relaxor ferroelectrics of 0.5Pb(Zn1/3Nb2/3)O3-0.5Pb(Zr0.47Ti0.53)O3 (0.5PZN-0.5PZT) near the morphotropic phase boundary (MPB) were prepared using the conventional oxide mixing method. The influence of sintering temperature on the phase transition and dielectrical response in the relaxor-ferroelectric-system 0.5PZN-0.5PZT has been investigated. X-ray diffraction analysis indicated that the phase of the material changed from an initially rhombohedral structure to a MPB structure and then a tetragonal structure when the sintering temperature is increased from 900 to 1250 °C. The corresponding grain size is enlarged from 1.1 ?m for predominantly rhombohedral to 2.5 ?m for more than 60% tetragonal, which obeys the common grain-growth law. The dielectric studies revealed that the indicator of the degree of diffuseness ? decreased with the increase of the sintering temperature from 900 to 1150 °C, indicating that the dielectric relaxor behavior was weakened, while at high sintering temperature above 1250 °C, ? increased subsequently, which was attributed to the Pb vacancy due to the formation of a pyrochlore phase. Raman analysis on the B-site cation order correlates well with the dielectric measurement results.

Chang, Li-Min; Hou, Yu-Dong; Zhu, Man-Kang; Yan, Hui

2007-02-01

52

Acute and obtuse rhombohedrons in the local structures of relaxor ferroelectric Pb(Mg1/3Nb2/3)O3  

NASA Astrophysics Data System (ADS)

The local structures around Nb and Pb in the prototypical relaxor ferroelectric Pb(Mg1/3Nb2/3)O3 (PMN) were investigated by x-ray fluorescence holography. The separate atomic images of nearest Pb around Nb revealed acute and obtuse rhombohedral structures of the crystal unit cells. The Pb-Pb correlated images showed a local structure of body-center-like 2a0×2a0×2a0 superlattice, proving a rigid three-dimensional network structural model combining the two kinds of rhombohedrons. The Pb atoms in the networks are positionally stable, while the other Pb atoms are fluctuating. This superstructure and the fluctuating Pb and Nb atoms are believed to play an important role in the relaxor behavior of PMN at the atomic level.

Hu, Wen; Hayashi, Kouichi; Ohwada, Kenji; Chen, Jun; Happo, Naohisa; Hosokawa, Shinya; Takahasi, Masamitu; Bokov, Alexei A.; Ye, Zuo-Guang

2014-04-01

53

Pyroelectric energy conversion using PLZT ceramics and the ferroelectric-ergodic relaxor phase transition  

NASA Astrophysics Data System (ADS)

This paper is concerned with direct conversion of waste heat into electricity by executing the Olsen cycle on lead lanthanum zirconate titanate (PLZT) ceramics undergoing a relaxor-ferroelectric phase transition. The Olsen cycle consists of two isothermal and two isoelectric field processes. First, the temperature-dependent dielectric properties were measured for x/65/35 PLZT. The polarization transition temperature of x/65/35 PLZT was found to decrease from 240 to 10?°C as x increased from 5 to 10 mol%. This suggests that the different compositions should be operated over different temperature ranges for maximum thermal to electrical energy conversion. The energy and power densities generated by the Olsen cycle using x/65/35 PLZT samples were measured by successively dipping the samples in isothermal dielectric oil baths. Large energy and power densities were obtained when the samples underwent the ergodic relaxor-ferroelectric phase transition. A maximum energy density of 1014 J l-1 per cycle was obtained with a 190 ?m thick 7/65/35 PLZT sample cycled at 0.026 Hz between 30 and 200?°C and between 0.2 and 7.0 MV m-1. To the best of our knowledge, this is the largest pyroelectric energy density ever demonstrated experimentally with ceramics, single crystals, or polymers. A maximum power density of 48 W l-1 was achieved using a 200 ?m thick 6/65/35 PLZT sample for temperatures between 40 and 210?°C and electric fields between 0 and 8.5 MV m-1 at a frequency of 0.060 Hz. The maximum applied electric field and temperature swings of these materials were physically limited by dielectric breakdown and thermomechanical stress.

Lee, Felix Y.; Ryul Jo, Hwan; Lynch, Christopher S.; Pilon, Laurent

2013-02-01

54

2-5 pyrochlore relaxor ferroelectric Cd2Nb2O7 and its Fe2+/Fe3+ modifications  

NASA Astrophysics Data System (ADS)

The weak-field dielectric dispersion (100 Hz-1.8 GHz) studies both of pure and Fe2+/Fe3 modified Cd2Nb2O7 ceramics over the temperature range of 90-380 K are presented and discussed from the viewpoint of relaxor and glassy properties of the system. It is revealed that Cd2Nb2O7 pyrochlore is intolerant of the addition of 25 mol % Fe2+ or Fe3+ for Cd2+. From the x-ray diffraction analysis, pure Cd2Nb2O7 forms a single-phase pyrochlore, while the compositions Cd1.5Fe0.52+Nb2O7 and Cd1.5Fe0.53+Nb2O7 give CdNb2O6 columbite doped with Fe2+ or Fe3+ on the Cd sites (<8 and <2 mol %, respectively), except for minor amount of parasitic hematite. The novel CdNb2O6 type compounds are not ferroelectrics, unlike Cd2Nb2O7. In the latter, at TC=196 K the dielectric relaxation due to the motion of ferroelectric domain walls driven by an external ac electric field is observed. A polydispersive dielectric response of Cd2Nb2O7 around 188 K has characteristics of the relaxor ferroelectrics with glassy behavior (like PMN). Near the characteristic freezing temperature of the zero-field-cooled state (Tf=183 K) the dielectric absorption spectra and the relaxation-time distribution strongly broaden and tend to flatten out, while below Tf the imaginary part of the dielectric permittivity becomes nearly frequency independent. The dielectric response of Cd2Nb2O7 dominating far below TC (around 150 K) and that of Fe2+/Fe3+ doped CdNb2O6 between 90 and 380 K are typical of glass-forming systems at temperature far above Tglass. The relaxational process is characterized by (i) a significant frequency dependence of the peak permittivity position, (ii) non-Arrhenius behavior, and (iii) increasing asymmetry of the dielectric absorption spectrum at the low-frequency side with decreasing temperature, without broadening the relaxation-time distribution and freezing the peak-absorption frequency. It is proposed that although the nature of structural disorder in Cd2Nb2O7 pyrochlore and Fe2+/Fe3+ doped CdNb2O6 columbite is different, in both systems the off-center displacements of the A-site ions act as a random field and are responsible for the relaxor and dipolar glass-like behavior upon cooling. The Debye-like HF dielectric relaxation (1 MHz-1.8 GHz) observed both in Cd2Nb2O7 and its isostructural analog Cd2Ta2O7 at RT and higher (a centrosymmetric phase) is attributed to fluctuations in polarization of the dynamically reoriented O(7th)-Cd-O(7th) dipoles due to dynamical off-center location of Cd ions.

Kolpakova, N. N.; Syrnikov, P. P.; Lebedev, A. O.; Czarnecki, P.; Nawrocik, W.; Perrot, C.; Szczepanska, L.

2001-12-01

55

Effect of SHI irradiation on NBT-BT ceramics: Transformation of relaxor ferroelectric to ferroelectric nature  

NASA Astrophysics Data System (ADS)

The lead free NBT-BT ceramics prepared by conventional solid state reaction method were irradiated with 120 MeV Au9+ ions with different fluences. The structural, dielectric and piezoelectric studies were carried out before and after irradiation. The agglomeration and increase of grain size are observed in SEM analysis after the irradiation. The diffuse phase transition disappeared after high fluence of irradiation and the material becomes ferroelectric in nature. The piezoelectric properties were decreased due to the reduced stability of the ferroelectric domains after the irradiation.

Shanmuga Sundari, S.; Kumar, Binay; Asokan, K.; Dhanasekaran, R.

2013-01-01

56

Real space mapping of polarization dynamics and hysteresis loop formation in relaxor-ferroelectric PbMg1/3Nb2/3O3 PbTiO3 solid solutions  

SciTech Connect

Polarization switching in ergodic relaxor and ferroelectric phases in the PbMg1/3Nb2/3O3 PbTiO3 (PMN-PT) system is studied using piezoresponse force microscopy, single point electromechanical relaxation measurements, and voltage spectroscopy mapping. The dependence of relaxation behavior on voltage pulse amplitude and time is found to follow a universal logarithmic behavior with a nearly constant slope. This behavior is indicative of the progressive population of slow relaxation states, as opposed to a linear relaxation in the presence of a broad relaxation time distribution. The role of relaxation behavior, ferroelectric nonlinearity, and the spatial inhomogeneity of the tip field on hysteresis loop behavior is analyzed in detail. The hysteresis loops for ergodic PMN-10%PT are shown to be kinetically limited, while in PMN with larger PT content, true ferroelectric hysteresis loops with low nucleation biases are observed.

Rodriguez, Brian [University College, Dublin; Jesse, Stephen [ORNL; Morozovska, A. N. [National Academy of Science of Ukraine, Kiev, Ukraine; Svechnikov, S. V. [National Academy of Science of Ukraine, Kiev, Ukraine; Kiselev, Dmitri [University of Aveiro, Portugal

2010-01-01

57

Central peak in light scattering from the relaxor ferroelectric PbMg1\\/3Nb2\\/3O3  

Microsoft Academic Search

A model relaxor ferroelectric PbMg1\\/3Nb2\\/3O3 (PMN) in single-crystal form has been studied by Raman scattering with special attention to the low-frequency spectra in the vicinity of both the diffuse ferroelectric transition (~270 K) and the electric-field-induced ferroelectric transition (~200 K). In addition to the hard-mode features without any pronounced change, a broad central component has been observed and analyzed. This

I. G. Siny; S. G. Lushnikov; R. S. Katiyar; E. A. Rogacheva

1997-01-01

58

Two-stage processes of electrically induced-ferroelectric to relaxor transition in 0.94(Bi1/2Na1/2)TiO3-0.06BaTiO3  

NASA Astrophysics Data System (ADS)

The stability of electrically induced long-range ferroelectric order in a relaxor 0.94(Bi1/2Na1/2)TiO3-0.06BaTiO3 ceramic material has been investigated by temperature-dependent X-ray diffraction and electrical property measurements. The depolarization and ferroelectric-to-relaxor transition are identified as separate and discrete processes. It is observed that the induced ferroelectric domains first lose their ferroelectric/ferroelastic texture coincident with a peak signal in the thermally induced depolarization current. With further increase in temperature, the detextured ferroelectric domains are dissociated into nanoscale entities. This fragmentation marks the ferroelectric-to-relaxor transition. It is suggested that the ferroelectric-to-relaxor transition has features of a second order phase transition.

Jo, Wook; Daniels, John; Damjanovic, Dragan; Kleemann, Wolfgang; Rödel, Jürgen

2013-05-01

59

Influence of composition on relaxor ferroelectric and electromechanical properties of poly(vinylidene fluoride-trifluoroethylene- chlorofluoroethylene)  

NASA Astrophysics Data System (ADS)

We investigate the influence of the composition, especially the chlorofluoroethylene content, on the ferroelectric and electromechanical properties of the poly(vinylidene fluoride-trifluoroethylene- chlorofluoroethylene) (PVDF-TrFE-CFE). It was found that increasing the CFE from 0 to 9 mol % gradually converts the normal ferroelectric of the copolymer (in the compositions range of VDF/TrFE mole ratio between 64/36 to 75/25) to a relaxor ferroelectric, resulting in a nearly hysteresis free polarization loop and high electrostrictive response. On the other hand, increasing CFE content causes reduction in crystallinity, which will affect the elastic modulus and the induced polarization level of the polymer. These competing effects determine the desired terpolymer compositions for given applications. The electromechanical strain as a function of induced polarization and macropolar phase fraction was modeled by a modified electrostrictive relation, which closely matches experimental data. It is found that the electrostrictive coefficient is relatively constant across the compositions investigated.

Klein, Rob J.; Xia, Feng; Zhang, Q. M.; Bauer, François

2005-05-01

60

Comprehensive characterization of surface acoustic wave resonators using relaxor based ferroelectric single crystals  

NASA Astrophysics Data System (ADS)

One-port surface acoustic wave resonators (SAW) were fabricated and characterized using Y-cut X propagating relaxor based ferroelectric single crystals of Pb(Mg1/3Nb2/3)O3-33%PbTiO3 and Pb(In1/3Nb2/3)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 (PIN-PMN-PT). The experimental results demonstrated ultrahigh electromechanical coupling factor K2 of ~60% for shear horizontal SAW and a relatively strong spurious resonance due to the Rayleigh-type SAW which can be sufficiently suppressed with Au electrode of large thickness. Characteristics of temperature stability, sensitivity to DC bias voltage, and homogeneity for the two resonators were evaluated and compared. The results showed similar instability of domain structure, and PIN-PMN-PT resonators have better temperature stability, but inferior homogeneity compared to that of PMN-33%PT resonators.

Chen, Jing; Han, Tao; Ji, Xiaojun; Zhao, Xiangyong; Luo, Haosu

2013-07-01

61

EXAFS study of lead-free relaxor ferroelectric BaTi1-xZrxO3 at the Zr K edge  

NASA Astrophysics Data System (ADS)

Extended x-ray absorption fine structure experiments at the Zr K edge were carried out on perovskite relaxor ferroelectrics BaTi1-xZrxO3 (BTZ) (x=0.25,0.30,0.35) , and on BaZrO3 for comparison. Structural information up to 4.5Å around the Zr atoms is obtained, revealing that the local structure differs notably from the average Pm3¯m cubic structure deduced from the x-ray diffraction. In particular, our results show that the distance between Zr atoms and their first oxygen neighbors is independent of the Zr substitution rate x and equal to that measured in BaZrO3 , while the x-ray cubic cell parameter increases linearly with x . Furthermore, we show that the Zr atoms tend to segregate in Zr-rich regions. We propose that the relaxor behavior in BTZ could be influenced by the random elastic fields generated by this particular chemical arrangement.

Laulhé, C.; Hippert, F.; Kreisel, J.; Maglione, M.; Simon, A.; Hazemann, J. L.; Nassif, V.

2006-07-01

62

Theory of radiation induced relaxor behavior of poly(vinylidene fluoride-trifluoroethylene) copolymers  

NASA Astrophysics Data System (ADS)

We propose a theory of the dynamic dielectric response in the organic ferroelectrics polyvinylidene fluoride (PVDF), poly(vinylidene fluoride/trifluoroethylene) [P(VDF/TrFE)] copolymer before and after irradiation by fast electrons. For this purpose, we use our random field formalism. In the adopted model we consider the earlier polymers as the disordered ferroelectrics in a mixed ferroglass phase (FG) with a coexistence of polar short- and long-range order regions. Short-range order regions correspond to amorphous layers, while long-range order regions appears in the crystalline phase of all-trans conformation. In our formalism, we account for the change of VDF content as well as for the influence of the irradiation, by variation of the content of electric dipoles and other random field sources. The downward shift of the paraferroelectric phase transition temperature and gradual transformation of the mixed FG phase into a dipole glass state with the increase of the irradiation dose was shown to be related to the self-consistent change of parameters of random field distribution function. We were able to fit the low-temperature dynamic dielectric response related to the amorphous phase by Vogel-Fulcher (V-F) law with parameters close enough to those observed in the experiment. The coincidence between calculated and measured behavior (namely, almost complete disappearance of high-temperature maxima, corresponding to the ferroelectric phase transition, their submergence into low-temperature maxima and V-F law for the low-temperature maxima of absorption) of the irradiated samples speaks in favor of irradiation induced relaxor behavior of P(VDF/TrFE) copolymers. We also discuss the physical reasons for the choice of the parameters of material necessary to fit our theory to the experiment.

Stephanovich, V. A.; Glinchuk, M. D.; Kirichenko, E. V.; Hilczer, B.

2003-11-01

63

Local structure in perovskite relaxor ferroelectrics: high-resolution 93Nb 3QMAS NMR.  

PubMed

Solid solutions of (1'-x)Pb(Mg(1/3)Nb(2/3))O3xPb(Sc(1/2)Nb(1/2))O3 (PMN/PSN) have been investigated using high-resolution 93Nb 3-quantum magic-angle spinning nuclear magnetic resonance experiments (3QMAS NMR). In previous MAS NMR investigations, the local B-cation ordering in these relaxor ferroelectric solid solutions was quantitatively determined. However, in conventional one-dimensional MAS spectra the effects of chemical shifts and quadrupole interaction are convoluted; this, in addition to the insufficient resolution, precludes reliable extraction of the values of isotropic chemical shift and quadrupole coupling product. In the current 3QMAS investigation, 93Nb spectra are presented for concentrations x=0, 0.1, 0.2, 0.6, 0.7, and 0.9 at high magnetic field (19.6 T) and fast sample spinning speed (35.7 kHz). Seven narrow peaks and two broad components are observed. The unique high-resolution of the two-dimensional 3QMAS spectra enables unambiguous and consistent assignments of spectral intensities to the specific 28 nearest B-site neighbor (nBn) configurations, (NMg, NSc, NNb) where each number ranges from 0 to 6 and their sum is 6. It is now possible to isolate the isotropic chemical shift and quadrupole coupling product and separately determine their values for most of the 28 nBn configurations. The isotropic chemical shift depends linearly on the number of Mg2+ cations in the configuration; delta iso CS=(13.7 +/- 0.1)NMg-970 +/- 0.4 ppm, regardless of the ratio NSc/NNb. For the seven Nb5+-deficient configurations (NMg, 6-NMg, 0) and the pure niobium configuration (0, 0, 6), the quadrupole coupling products (and hence the electric field gradients) are small (PQ approximately 6-12 MHz) and for the remaining configurations containing small, ferroelectric active Nb5+ ions, the quadrupole coupling products are significantly larger (PQ approximately 40 MHz), indicating larger electric field gradients. PMID:15040979

Zhou, Donghua H; Hoatson, Gina L; Vold, Robert L

2004-04-01

64

Local structure in perovskite relaxor ferroelectrics: high-resolution 93Nb 3QMAS NMR  

NASA Astrophysics Data System (ADS)

Solid solutions of (1- x)Pb(Mg 1/3Nb 2/3)O 3xPb(Sc 1/2Nb 1/2)O 3 (PMN/PSN) have been investigated using high-resolution 93Nb 3-quantum magic-angle spinning nuclear magnetic resonance experiments (3QMAS NMR). In previous MAS NMR investigations, the local B-cation ordering in these relaxor ferroelectric solid solutions was quantitatively determined. However, in conventional one-dimensional MAS spectra the effects of chemical shifts and quadrupole interaction are convoluted; this, in addition to the insufficient resolution, precludes reliable extraction of the values of isotropic chemical shift and quadrupole coupling product. In the current 3QMAS investigation, 93Nb spectra are presented for concentrations x=0, 0.1, 0.2, 0.6, 0.7, and 0.9 at high magnetic field (19.6 T) and fast sample spinning speed (35.7 kHz). Seven narrow peaks and two broad components are observed. The unique high-resolution of the two-dimensional 3QMAS spectra enables unambiguous and consistent assignments of spectral intensities to the specific 28 nearest B-site neighbor (nBn) configurations, ( NMg, NSc, NNb) where each number ranges from 0 to 6 and their sum is 6. It is now possible to isolate the isotropic chemical shift and quadrupole coupling product and separately determine their values for most of the 28 nBn configurations. The isotropic chemical shift depends linearly on the number of Mg 2+ cations in the configuration; ?isoCS=(13.7±0.1) NMg-970±0.4 ppm, regardless of the ratio NSc/ NNb. For the seven Nb 5+-deficient configurations ( NMg, 6- NMg, 0) and the pure niobium configuration (0, 0, 6), the quadrupole coupling products (and hence the electric field gradients) are small ( PQ˜6-12 MHz) and for the remaining configurations containing small, ferroelectric active Nb 5+ ions, the quadrupole coupling products are significantly larger ( PQ˜40 MHz), indicating larger electric field gradients.

Zhou, Donghua H.; Hoatson, Gina L.; Vold, Robert L.

2004-04-01

65

Enhanced dielectric constant and relaxor behavior realized by dual stage sintering of Sr0.5Ba0.5Nb2O6  

NASA Astrophysics Data System (ADS)

The relaxor ferroelectric compound, Sr0.5Ba0.5Nb2O6 (SBN50) was synthesized by solid state reaction followed by sintering under two different conditions: single and dual stage sintering. The impact of sintering process on structural and dielectric properties has been studied in detail using X-ray diffraction, scanning electron microscopy and broadband dielectric spectroscopy. The crystal structure determined by performing Rietveld refinement of X-ray diffractogram was found to be identical in both cases. SBN50 crystallizes in the ferroelectric tetragonal tungsten bronze, P4bm structure. It was observed that uniform grain growth can be controlled by dual stage sintering and relatively narrow distribution of grains can be achieved with an average grain size of ˜15 ?m. The dielectric studies show that SBN50 exhibits a relaxor ferroelectric behavior with the transformation taking place at ˜ 380 K due to formation of polar nano regions. Although both single and dual stage sintered SBN50 exhibits relaxor behaviour, the maximum dielectric constant of dual stage sintered SBN50 is found to be 1550 compare to 1440 for single stage sintering.

Rathore, Satyapal S.; Vitta, Satish

2014-04-01

66

Relaxor behavior of CaxBa1-xNb2O6 (0.18?x?0.35) tuned by Ca/Ba ratio and investigated by resonant ultrasound spectroscopy  

NASA Astrophysics Data System (ADS)

Dependence of relaxor behavior of incompletely filled tetragonal tungsten bronze uniaxial relaxor ferroelectric calcium barium niobate (CaxBa1-xNb2O6, CBN-x) on its composition was investigated by varying Ca/Ba ratio (0.18 ? x ? 0.35) and studying its thermal and elastic properties. Recently, we have reported the relaxor behavior CBN-28 with the evidence of the existence of the Burns temperature TB, and the intermediate characteristic temperature T* [Pandey , Phys. Rev. BPRBMDO1098-012110.1103/PhysRevB.84.174102 84, 174102 (2011)]. In this work, we show that the dynamics of polar nanoregions (and hence the relaxor behavior) strongly varies with the Ca/Ba ratio. Evidence is found for a more pronounced relaxor behavior with increasing x. The Curie temperature and the Burns temperature are also very sensitive to the composition, whereas the characteristic temperature T* appears unaffected from the Ca/Ba ratio. The bonding interaction has been explained on the basis of bulk modulus, Poisson's ratio, and deviation from Cauchy relations. Presented results open the perspective to understand the variation of relaxor behavior of CBN-x (˜0.18?x?˜0.35) above Curie temperature.

Pandey, Chandra Shekhar; Schreuer, Jürgen; Burianek, Manfred; Mühlberg, Manfred

2013-03-01

67

Non-linear permittivity study of the crossover from ferroelectric to relaxor and cluster glass in BaTi1-xSnxO3 (x = 0.175-0.30)  

NASA Astrophysics Data System (ADS)

The electric susceptibilities ?1, ?2, and ?3 of BaTi1-xSnxO3 ceramics with 0.175 ? x ? 0.30 are measured at 90 ? T ? 350 K and 37 ? f ? 106 Hz. Crossover from ferroelectric (x = 0.175) to relaxor behavior (x = 0.30) via coexistence of both (x = 0.25) is indicated by increasing polydispersivity and suppression of ?2 intensity. The relaxor properties are due to weak random fields acting on dipolar Ti4+ clusters in non-polar Sn4+ environment. Upon cooling frustrated interaction between the blocked polar nanoregions yields a cluster glass ground state for x = 0.30 as verified by the dynamic criticality of ?1, ?3, and the scaled non-linear susceptibility a3.

Kleemann, W.; Miga, S.; Xu, Z. K.; Lu, S. G.; Dec, J.

2014-05-01

68

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

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.%.

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

69

Structural phase transitions in the relaxor ferroelectric Pb{sub 2}Bi{sub 4}Ti{sub 5}O{sub 18}  

SciTech Connect

The relaxor ferroelectric Pb{sub 2}Bi{sub 4}Ti{sub 5}O{sub 18} has been studied by Rietveld refinement of powder neutron diffraction data collected at temperatures of 100, 250 and 400 deg. C. Our refinements are compatible with the 'average' crystal structure of Pb{sub 2}Bi{sub 4}Ti{sub 5}O{sub 18} undergoing the phase transition sequence F2mm->I4mm->I4/mmm as a function of increasing temperature, with the latter phase being observed above the known ferroelectric Curie temperature, T{sub m}, and the intermediate phase consistent with a previously observed dielectric anomaly around 207 deg. C. The results are, however, in conflict with both observation of a symmetry lowering (to space group B2eb) in the lowest temperature phase, observed by electron diffraction, and also with electrical property measurements, which suggest both a- and c-axis polarisation up to T{sub m}. Nevertheless, these crystallographic results are consistent with the observation of relaxor behaviour in this material, and underline the importance of considering 'long-range' versus 'local' structural effects in relaxor materials. - Abstract: A powder neutron diffraction study suggests that the relaxor ferroelectric Pb{sub 2}Bi{sub 4}Ti{sub 5}O{sub 18} undergoes the phase transition sequence F2mm-I4mm-I4/mmm with increasing temperature. Display Omitted

Goff, Richard J. [EaStChem, School of Chemistry, University of St. Andrews, St. Andrews, Fife, KY16 9ST (United Kingdom); Lightfoot, Philip, E-mail: pl@st-and.ac.u [EaStChem, School of Chemistry, University of St. Andrews, St. Andrews, Fife, KY16 9ST (United Kingdom)

2009-10-15

70

Observation of relaxor ferroelectricity and multiferroic behaviour in nanoparticles of the ferromagnetic semiconductor La(2)NiMnO(6).  

PubMed

We report a diffuse phase transition (extending over a finite temperature range of ?50 K) in sol-gel derived nanoparticles (?25 nm) of the ferromagnetic double perovskite La(2)NiMnO(6). The macroscopic polarization (P-E hysteresis loop), validity of the Vogel-Fulcher relation and high dielectric permittivity (?9 × 10(2)) confirm relaxor ferroelectric phenomena in these magnetic nanoparticles. Compared to the corresponding bulk sample, appreciably large enhancement of the magnetocapacitive effect (MC  ? 30%) is observed even under low magnetic field (0.5 T) around the broad relaxor dielectric peak temperature (?220 K), which is close to the ferromagnetic transition temperature (?(f) ? 196 K). All of these features establish the multiferroic character of the La(2)NiMnO(6) nanoparticles. The inhomogeneities arising from chemical and valence mixing in the present La(2)NiMnO(6) nanoparticles and the inter-site, Ni/Mn-site disorder along with surface disorder of the individual nanoparticles resulting in local polar regions are attributed to the observed dielectric behaviour of the nanoparticles. The wave vector dependent spin-pair correlation is considered to be the plausible cause of the colossal magnetocapacitive response near the transition temperature. High permittivity and large magnetocapacitive properties make these ferromagnetic La(2)NiMnO(6) nanoparticles technologically important. PMID:22738874

Masud, Md G; Ghosh, Arijit; Sannigrahi, J; Chaudhuri, B K

2012-07-25

71

X-ray Intensity Fluctuation Spectroscopy Using Nanofocused Hard X-rays: Its Application to Study of Relaxor Ferroelectrics  

NASA Astrophysics Data System (ADS)

The use of a combination of coherent X-rays from a third-generation synchrotron light source and ultraprecise Kirkpatrick-Baez mirrors enables us to apply nanofocused hard X-rays in solid-state physics. We developed an apparatus for X-ray intensity fluctuation spectroscopy using the nanofocused hard X-rays and applied it to the study of relaxor ferroelectrics. We have successfully detected a large and slow intensity fluctuation of scattered X-rays above cubic-to-tetragonal phase transition temperature with a characteristic time scale on the order of 10 s. We speculated that the intensity fluctuation originates from domain number fluctuation, which is directly related to the dielectric response, particularly the frequency dispersion.

Kenji Ohwada,; Kazumichi Namikawa,; Susumu Shimomura,; Hironori Nakao,; Hidekazu Mimura,; Kazuto Yamauchi,; Mitsuyoshi Matsushita,; Jun'ichiro Mizuki,

2010-02-01

72

Low-firing PZN–PFN–PFW relaxor ferroelectric ceramics produced by a reaction-sintering process  

Microsoft Academic Search

Pb((Zn1\\/3Nb2\\/3)0.16(Fe1\\/2Nb1\\/2)0.48(Fe2\\/3W1\\/3)0.36)O3 (PZFNW) relaxor ferroelectric ceramics produced by a reaction-sintering process of low sintering temperatures were investigated. Without any calcination, the mixture of PbO, Zn(NO3)2, Fe(NO3)3, Nb2O5 and WO3 was pressed and sintered directly. PZFNW ceramics of 100% perovskite phase were obtained after sintering at 830–950°C. A density of 8.66gcm?3 (98.6% of theoretical value) was obtained after sintering at 930°C for

Yi-Cheng Liou; Cheng-Jung Chuang; Yi-Che Shih

2005-01-01

73

Growth of the chemically ordered domains in PMN-type relaxor ferroelectrics  

Microsoft Academic Search

The “space charge” models for the structure of the Pb(Mg1\\/3Nb2\\/3)O3 (PMN) family of relaxors are based, in part, on the apparent absence of any change in the degree of chemical order with extended thermal treatment and the observation of an increase in the ordering in donor-doped PLMN solid solutions. Through experiments on the tantalate relaxor, Pb(Mg1\\/3Ta2\\/3)O3(PMT), we have found that

Peter K. Davies; Mehmet A. Akbas

1999-01-01

74

Finite-temperature properties of Ba(Zr,Ti)O3 relaxors from first principles.  

PubMed

A first-principles-based technique is developed to investigate the properties of Ba(Zr,Ti)O(3) relaxor ferroelectrics as a function of temperature. The use of this scheme provides answers to important, unresolved and/or controversial questions such as the following. What do the different critical temperatures usually found in relaxors correspond to? Do polar nanoregions really exist in relaxors? If yes, do they only form inside chemically ordered regions? Is it necessary that antiferroelectricity develop in order for the relaxor behavior to occur? Are random fields and random strains really the mechanisms responsible for relaxor behavior? If not, what are these mechanisms? These ab initio based calculations also lead to deep microscopic insight into relaxors. PMID:23004657

Akbarzadeh, A R; Prosandeev, S; Walter, Eric J; Al-Barakaty, A; Bellaiche, L

2012-06-22

75

Finite-Temperature Properties of Ba(ZrTi)O3 Relaxors from First Principles  

NASA Astrophysics Data System (ADS)

A first-principles-based technique is developed to investigate the properties of Ba(ZrTi)O3 relaxor ferroelectrics as a function of temperature. The use of this scheme provides answers to important, unresolved and/or controversial questions such as the following. What do the different critical temperatures usually found in relaxors correspond to? Do polar nanoregions really exist in relaxors? If yes, do they only form inside chemically ordered regions? Is it necessary that antiferroelectricity develop in order for the relaxor behavior to occur? Are random fields and random strains really the mechanisms responsible for relaxor behavior? If not, what are these mechanisms? These ab initio based calculations also lead to deep microscopic insight into relaxors.

Prosandeev, Sergey; Akbarzadeh, Ali; Walter, Eric; Al-Barakaty, Abdullah; Bellaiche, Laurent

2013-03-01

76

Finite-Temperature Properties of Ba(Zr,Ti)O3 Relaxors from First Principles  

NASA Astrophysics Data System (ADS)

A first-principles-based technique is developed to investigate the properties of Ba(Zr,Ti)O3 relaxor ferroelectrics as a function of temperature. The use of this scheme provides answers to important, unresolved and/or controversial questions such as the following. What do the different critical temperatures usually found in relaxors correspond to? Do polar nanoregions really exist in relaxors? If yes, do they only form inside chemically ordered regions? Is it necessary that antiferroelectricity develop in order for the relaxor behavior to occur? Are random fields and random strains really the mechanisms responsible for relaxor behavior? If not, what are these mechanisms? These ab initio based calculations also lead to deep microscopic insight into relaxors.

Akbarzadeh, A. R.; Prosandeev, S.; Walter, Eric J.; Al-Barakaty, A.; Bellaiche, L.

2012-06-01

77

Bi(Ni1/2Zr1/2)O3-PbTiO3 relaxor-ferroelectric films for piezoelectric energy harvesting and electrostatic storage  

NASA Astrophysics Data System (ADS)

In this Letter, we demonstrated that both a high energy-storage density and a large piezoelectric response can be attained simultaneously in relaxor-ferroelectric 0.4Bi(Ni1/2Zr1/2)O3-0.6PbTiO3 films prepared by chemical solution deposition. The as-prepared films had a pure-phase perovskite structure with an excellent crystalline morphology, featuring a moderate relative permittivity ( ? r ˜ 800-1100), a low dissipation factor ( tan ? < 5%) and strong relaxor-like behavior ( ? = 1.81). An ultra-high energy-storage density of 39.8 J/cm3 at 2167 kV/cm was achieved at room temperature. Moreover, the 0.4Bi(Ni1/2Zr1/2)O3-0.6PbTiO3 films exhibited a considerably large effective piezoelectric coefficient of 83.1 pm/V under substrate clamping, which is comparable to the values obtained for lead zirconate titanate films. Good thermal stabilities in both the energy-storage performance and the piezoelectric properties were obtained over a wide range of temperatures, which makes 0.4Bi(Ni1/2Zr1/2)O3-0.6PbTiO3 films a promising candidate for high energy-storage embedded capacitors, piezoelectric micro-devices, and specifically for potential applications in next-generation integrated multifunctional piezoelectric energy harvesting and electrostatic storage systems.

Xie, Zhenkun; Yue, Zhenxing; Ruehl, Griffin; Peng, Bin; Zhang, Jie; Yu, Qi; Zhang, Xiaohua; Li, Longtu

2014-06-01

78

High Tm lead-free relaxor ferroelectrics with broad temperature usage range: 0.04BiScO3-0.96(K0.5Na0.5)NbO3  

NASA Astrophysics Data System (ADS)

In order to develop high temperature lead-free relaxors, xBiScO3-(1-x)(K0.5Na0.5)NbO3[xBS-(1-x)KNN] ceramics were proposed using a tolerance factor approach. To verify this proposal, xBS-(1-x)KNN ceramics were synthesized by conventional solid-state sintering. A stable perovskite phase was obtained when KNN content was greater than 96 mol %. The diffuse phase transition and frequency dispersion of the dielectric constant, which are two typical characteristics of relaxor ferroelectrics, were observed in xBS-(1-x)KNN ceramics. The dielectric relaxor behavior follows a modified Curie-Weiss law relationship. In addition, 0.04BS-0.96KNN ceramics show a broad and stable permittivity maximum near 2500 from 100 to 300 °C and lower dielectric loss (<5%) at broad temperature usage range (100-300 °C). The results indicate that this material may have great potential for high temperature capacitors in automobile applications.

Du, Hongliang; Zhou, Wancheng; Luo, Fa; Zhu, Dongmei; Qu, Shaobo; Li, Ye; Pei, Zhibin

2008-08-01

79

Optical properties of epitaxial relaxor ferroelectric PbSc0.5Nb0.5O3 films  

NASA Astrophysics Data System (ADS)

The optical properties of epitaxial perovskite-structure relaxor ferroelectric PbSc0.5Nb0.5O3 thin films are studied in broad spectral and temperature ranges by variable-angle spectroscopic ellipsometry. The films possess a metrically tetragonal crystal structure with a biaxial in-plane compressive strain of 0.1%-0.8%. The optical constants of the films with thickness of 10-50 nm are determined accurately using the advanced ellipsometry technique. The dramatic changes in the spectra of the dielectric functions and the absorption coefficient are found under various strain conditions. The characteristic energies of the spectra, including the bandgaps, vary by 0.1-0.5 eV. A frustration of the ferroelectric phase transition is evidenced by thermo-optical studies. A complex relationship between strain, polarization, and optical properties is discussed in terms of possible ionic displacements in metrically tetragonal PbSc0.5Nb0.5O3 films.

Lynnyk, A.; Chvostova, D.; Pacherova, O.; Kocourek, T.; Jelinek, M.; Dejneka, A.; Tyunina, M.

2013-09-01

80

Study of the relaxor behavior in BaTi 1- xHf xO 3 (0.20 ? x ? 0.30) ceramics  

NASA Astrophysics Data System (ADS)

The influence of Hf doping on the structure and dielectric properties of BaTiO 3 has been studied. For this purpose Ba(Ti 1- xHf x)O 3 ceramics were prepared through solid-state reaction route at close compositions, having x = 0.20, 0.22, 0.23 and 0.30. The study was aimed to locate the exact hafnium concentration for normal to relaxor crossover in these ceramics. X-ray diffraction followed by Rietveld refinement, reveals the formation of single phase with Pm3 m cubic structure. Temperature and frequency dependence of real ( ?') and imaginary ( ??) parts of the dielectric permittivity have been studied in the temperature range of 90-350 K, at frequencies between 0.1 kHz and 100 kHz. The dielectric permittivity variations with temperature show deviation from Curie-Weiss behavior and strong frequency dispersion. The deviation from Curie-Weiss behavior, discontinuous jump along with the change in the slope of Tm vs Hf concentration plot, and the degree of relaxation ( ?) approaching ˜2, indicate a crossover from normal to relaxor ferroelectrics. Substitution of Hf 4+ for Ti 4+ in BaTiO 3 introduces structural disorder, causing perturbations like local electric and strain fields. These perturbations reduce the long-range polar order resulting in relaxor behavior.

Anwar, Shahid; Sagdeo, P. R.; Lalla, N. P.

2007-11-01

81

Anelastic relaxor behavior of Pb(Mg1/3Nb2/3)O3  

NASA Astrophysics Data System (ADS)

Elastic storage modulus and loss of relaxor lead magnesium niobate ceramics, Pb(Mg1/3Nb2/3)O3, have been measured with dynamic mechanical analyzer in single cantilever mode in the temperature range from 170 K to 320 K and at frequencies from 0.1 Hz to 50 Hz. The dependence of the elastic susceptibility (inverse modulus) on temperature and frequency of the driving force has characteristics of typical relaxor behavior that can be well described with the Vogel-Fulcher law. The parameters of the Vogel-Fulcher relation exhibit similar values for the dielectric and anelastic relaxations. Similarities and differences between anelastic and dielectric relaxor behaviors are identified.

Urši?, Hana; Damjanovic, Dragan

2013-08-01

82

Low-temperature dielectric behavior of BiFeO3-modified CaTiO3 incipient ferroelectric ceramics  

NASA Astrophysics Data System (ADS)

CaTiO3 incipient ferroelectric ceramics have been modified by introducing BiFeO3. The single-phase (Ca1-yBiy)(Ti1-yFey)O3 solid solutions in space group Pbnm at room temperature are obtained for y <= 0.7. An obvious relaxor dielectric peak is induced in the present ceramics, and the peak temperature Tm increases with increasing y, where the dielectric constant as function of temperature can be well fitted with Barrett equation. The monotonic increase of T1 and T0 and decrease of (T1 - 2T0) in Barrett equation with increasing y suggest an approximation to the ferroelectric behavior, where the ferroelectric ordering becomes stronger compared with the quantum fluctuations. That is, the ferroelectric transition can be induced by introducing BiFeO3 in CaTiO3 incipient ferroelectric ceramics.

Qing Wang, Qing; Jian Zhao, Hong; Ming Chen, Xiang

2012-06-01

83

Phase structure, dielectric properties, and relaxor behavior of (K{sub 0.5}Na{sub 0.5})NbO{sub 3}-(Ba{sub 0.5}Sr{sub 0.5})TiO{sub 3} lead-free solid solution for high temperature applications  

SciTech Connect

The (1-x)(K{sub 0.5}Na{sub 0.5})NbO{sub 3}-x(Ba{sub 0.5}Sr{sub 0.5})TiO{sub 3} (KNN-BST) solid solution has been synthesized by conventional solid-state sintering in order to search for the new lead-free relaxor ferroelectrics for high temperature applications. The phase structure, dielectric properties, and relaxor behavior of the (1-x)KNN-xBST solid solution are systematically investigated. The phase structure of the (1-x)KNN-xBST solid solution gradually changes from pure perovskite phase with an orthorhombic symmetry to the tetragonal symmetry, then to the pseudocubic phase, and to the cubic phase with increasing addition of BST. The 0.90KNN-0.10BST solid solution shows a broad dielectric peak with permittivity maximum near 2500 and low dielectric loss (<4%) in the temperature range of 100-250 deg. C. The result indicates that this material may have great potential for a variety of high temperature applications. The diffuse phase transition and the temperature of the maximum dielectric permittivity shifting toward higher temperature with increasing frequency, which are two typical characteristics for relaxor ferroelectrics, are observed in the (1-x)KNN-xBST solid solution. The dielectric relaxor behavior obeys a modified Curie-Weiss law and a Vogel-Fulcher relationship. The relaxor nature is attributed to the appearance of polar nanoregions owing to the formation of randon fields including local electric fields and elastic fields. These results confirm that the KNN-based relaxor ferroelectrics can be regarded as an alternative direction for the development of high temperature lead-free relaxor ferroelectrics.

Du Hongliang; Zhou Wancheng; Luo Fa; Zhu Dongmei [State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi'an 710072 (China); Qu Shaobo [Electronic Materials Research Laboratory and Key Laboratory of Educational Ministry, Xi'an Jiaotong University, Xi'an 710049 (China); Pei Zhibin [The College of Science, Air Force Engineering University, Xi'an 710051 (China)

2009-06-15

84

DURIP 00 Thermal Analysis and Potentiostatic Instuments for Relaxor Ferroelectric Research.  

National Technical Information Service (NTIS)

The funds provided by this grant were used to purchase a thermoanalytical balance, with additional thermal analytical capabilities, and a general purpose potentiostat/galvanostat in support of ongoing research on the thermochemistry of ferroelectric relax...

W. Petuskey

2001-01-01

85

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

NASA Astrophysics Data System (ADS)

Waste heat can be directly converted into electrical energy by performing the Olsen cycle on pyroelectric materials. The Olsen cycle consists of two isothermal and two isoelectric field processes in the electric displacement versus electric field diagram. This paper reports on the electrical energy generated by lanthanum-doped lead zirconate titanate (8/65/35 PLZT) subjected to the Olsen cycle. The material was alternately dipped into a cold and a hot silicone oil bath under specified electric fields. A maximum energy density of 888 J l-1/cycle was obtained with a 290 µm thick 8/65/35 PLZT sample for temperatures between 25 and 160?°C and electric fields cycled between 0.2 and 7.5 MV m-1. To the best of our knowledge, this is the largest pyroelectric energy density experimentally measured with multiple cycles. It corresponded to a power density of 15.8 W l-1. The electrical breakdown strength and therefore the energy and power densities of the material increased as the sample thickness was reduced from 720 to 290 µm. Furthermore, a physical model for estimating the energy harvested by ferroelectric relaxors was further validated against experimental data for a wide range of electric fields and temperatures.

Lee, Felix Y.; Goljahi, Sam; McKinley, Ian M.; Lynch, Christopher S.; Pilon, Laurent

2012-02-01

86

Two-component Model of the Neutron Diffuse Scattering in the Relaxor Ferroelectric PZN-4.5%PT  

SciTech Connect

We report measurements of the neutron diffuse scattering in a single crystal of the relaxor ferroelectric material 95.5% Pb(Zn{sub 1/3}Nb{sub 2/3})O{sub 3}-4.5%PbTiO{sub 3}. Our results suggest that the nanometer scale structure in this compound exhibits both <100> and <110> polarizations, which contribute to different portions of the total diffuse scattering intensity. These contributions can be distinguished by the differing responses to an electric field applied along [001]. While diffuse scattering intensities associated with <110> (T2-type) polarizations show little to no change in a [001] field, those associated with <100> (T1-type) polarizations are partially suppressed by the field at temperatures below the Curie temperature T{sub C} {approx} 475 K. Neutron spin-echo measurements show that the diffuse scattering at (0.05,0,1) is largely dynamic at high temperature and gradually freezes on cooling, becoming mostly static at 200 K.

Xu, Z.; Wen, J.; Xu, G.; Stock, C.; Gardner, J.S.; Gehring, P.M.

2010-10-28

87

Electric-field-temperature phase diagram of the ferroelectric relaxor system (1 - x)Bi1/2Na1/2TiO3 - xBaTiO3 doped with manganese  

NASA Astrophysics Data System (ADS)

The electric-field-temperature phase diagram for the lead-free relaxor material (1 - x)(Bi1/2Na1/2)TiO3 - xBaTiO3 (x = 0.03, 0.06, and 0.09) doped with 0.5 mol% Mn (BNT-100xBT:Mn) was established. Transition lines between ergodic or nonergodic relaxor states and the field-induced ferroelectric state were determined at constant temperatures with electric-field-dependent measurements of the polarization as well as of the piezoelectric coefficient and permittivity. Near the depolarization temperature Td, the switching between two ferroelectric poling directions occurs in two steps via an intermediate relaxor state. This effect is closely related to the pinching of the ferroelectric hysteresis loop.

Sapper, Eva; Novak, Nikola; Jo, Wook; Granzow, Torsten; Rödel, Jürgen

2014-05-01

88

X-ray absorption spectroscopy of Ru-doped relaxor ferroelectrics with a perovskite-type structure  

NASA Astrophysics Data System (ADS)

X-ray absorption near-edge structure and extended x-ray absorption fine structure spectroscopy at the Ru K edge of Ru-doped PbSc0.5Ta0.5O3 (PST-Ru), PbSc0.5Nb0.5O3 (PSN-Ru), and 0.9PbZn1/3Nb2/3O3-0.1PbTiO3 (PZN-0.1PT-Ru) as well as at the Ta L3 edge of PST-Ru and the Nb K edge of PSN-Ru was applied to study the short- and intermediate-range atomic arrangements in perovskite-type (ABO3) relaxor ferroelectrics. The compounds were also analyzed by complementary Raman scattering, visible/near-visible absorption spectroscopy, and synchrotron x-ray single-crystal diffraction. The results show that Ru is octahedrally coordinated in all three relaxor host matrices but the average oxidation state of Ru in PST-Ru and PSN-Ru is ˜4.4, whereas it is ˜3.8 in PZN-0.1PT-Ru. In PbSc0.5B''0.5O3 (B'' = Ta, Nb) Ru substitutes for the B'' cations in the form of isolated point defects, while in PZN-0.1PT-Ru Ru replaces adjacent A and B sites, forming a chainlike structural species of face-sharing elongated octahedra. Chemical 1:1 B-site order as well as dynamic BO6 tilting is observed around both the Ru dopant and the major B'' cation in PST-Ru and PSN-Ru regardless of the fact that according to x-ray diffraction at ambient conditions, the average structure is cubic with weak or no long-range chemical order. Pb cations are off-center displaced from the prototypic cubic A site for all three compounds and in Ru-doped PbSc0.5B''0.5O3 the BO6 tilt angle correlates with the degree of coherent B-Pb distances.

Vitova, T.; Mangold, S.; Paulmann, C.; Gospodinov, M.; Marinova, V.; Mihailova, B.

2014-04-01

89

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

NASA Astrophysics Data System (ADS)

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.

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

2013-09-01

90

Effect of dead layer and strain on diffuse phase transition of PLZT relaxor thin films.  

SciTech Connect

Bulk relaxor ferroelectrics exhibit excellent permittivity compared to their thin film counterpart, although both show diffuse phase transition (DPT) behavior unlike normal ferroelectrics. To better understand the effect of dead layer and strain on the observed anomaly in the dielectric properties, we have developed relaxor PLZT (lead lanthanum zirconate titanate) thin films with different thicknesses and measured their dielectric properties as a function of temperature and frequency. The effect of dead layer on thin film permittivity has been found to be independent of temperature and frequency, and is governed by the Schottky barrier between the platinum electrode and PLZT. The total strain (thermal and intrinsic) in the film majorly determines the broadening, dielectric peak and temperature shift in the relaxor ferroelectric. The Curie-Weiss type law for relaxors has been further modified to incorporate these two effects to accurately predict the DPT behavior of thin film and bulk relaxor ferroelectrics. The dielectric behavior of thin film is predicted by using the bulk dielectric data from literature in the proposed equation, which agree well with the measured dielectric behavior.

Tong, S.; Narayanan, M.; Ma, B.; Koritala, R. E.; Liu, S.; Balachandran, U.; Shi, D. (Energy Systems); ( MSD); (Univ. of Cincinnati)

2011-02-01

91

Study of optical phonon lifetimes near the diffuse phase transition in relaxor ferroelectric thin films  

NASA Astrophysics Data System (ADS)

We have studied the lattice dynamical properties of oriented Pb(Sc0.5Nb0.25Ta0.25)O3 (PSNT) thin films by micro-Raman spectroscopy in the temperature range of 80-450 K. An anomalous temperature dependence of the integrated intensity and Raman linewidths was found near the diffuse phase transition. The phonon lifetime analysis indicates strong damping of A1g mode phonons near the transition. This analysis falls into two regimes: below the transition an increase in the lifetime with very small activation energy (Ea~0.001 eV) is found, and above the transition an increase in the lifetime with higher activation energy (Ea~0.018 eV) is fitted. Although the activation energy calculated from the dielectric loss spectra matched within a factor of 3 with the phonon lifetime energy calculations at all temperatures, we interpret these data as non-equilibrium phenomena due to a relaxation bottleneck in a glassy system (Littlewood and Rammal 1988 Phys. Rev. B 38 2675). Whenever activation energy E \\ll kT is fitted, one should suspect such processes, and they are known in polyvinylidene fluoride (Zhang 1998 Science 280 2101; Scott 2006 J. Phys.: Condens. Matter 18 7123). The new data provide a new way of characterizing non-equilibrium processes in relaxors.

Correa, Margarita; Kumar, Ashok; Katiyar, R. S.; Scott, J. F.

2008-03-01

92

Modeling of fatigue behavior in relaxor piezocrystals: Improved characteristics by Mn substitution  

NASA Astrophysics Data System (ADS)

The functional form of the time decay of the remanent polarization under high-electrical drives, known as fatigue, has been derived for relaxor piezoelectric materials based on the hierarchical relaxation process, typical of disordered systems such as random-field and glassy states and is given in terms of normalized remanent polarization (Pr) as Pr(t)=Pot-x exp[-c(t/?)?]. This function was verified by fitting the dynamics of the fatigue behavior in 0.92Pb(Zn1/3Nb2/3)O3-0.08 PbTiO3 (PZN-PT) relaxor-based piezoelectric system. Mn modification of a PZN-PT single crystal improved the fatigue behavior by slowing down the relaxation processes and pinning the domain wall motion.

Priya, Shashank; Kim, Hyeoung Woo; Ryu, Jungho; Zhang, Shujun; Shrout, Thomas R.; Uchino, Kenji

2002-10-01

93

Electric-field-induced transformations in epitaxial relaxor ferroelectric PbMg1/3Nb2/3O3 films  

NASA Astrophysics Data System (ADS)

Electric-field-induced transformations are studied experimentally in cube-on-cube-type epitaxial film of relaxor ferroelectric (FE) PbMg1/3Nb2/3O3 grown on (001) MgO substrate. The dielectric response, polarization, and current are measured along the out-of-plane <100> direction of the film and analyzed as a function of temperature, frequency, and applied field. Compared to the <100> crystal, transformation of the low-temperature relaxor state to a new state in the (001) film takes place at considerably lower temperatures and larger fields. Based on the found bisigmoidal shape and the two scaling regimes of the current-voltage curves, the two corresponding electric-field-induced processes are suggested to be dipolar flips and flow of a phase boundary in the film. The field-induced state in the film is dynamic and unstable, and it differs from the field-induced FE state in the crystal. The robustness of the relaxor state to electric field in the film is discussed in relation to spatial anisotropy of the dipolar system in the (001) film.

Tyunina, M.; Pintilie, I.; Iuga, A.; Pintilie, L.

2014-03-01

94

Relaxor-like dielectric behavior in La 2NiMnO 6 double perovskite ceramics  

Microsoft Academic Search

The dielectric and conductive characteristics of La2NiMnO6 double perovskite ceramics were investigated together with the crystal structure. La2NiMnO6 ceramics crystallized in the monoclinic P21\\/n structure in which the Ni2+ and Mn4+ ions ordered periodically. Relaxor-like dielectric behavior combined with a giant dielectric constant step was observed in the present ceramics, and these unique dielectric characteristics should be attributed to the

Y. Q. Lin; X. M. Chen; X. Q. Liu

2009-01-01

95

Crystalline properties of ferroelectric-relaxor PMN-PT thin films by pulsed laser deposition  

Microsoft Academic Search

The dielectric and crystalline properties of ferroelectric thin films of 0.9[Pb(Mg13\\/Nb23\\/)O3]-0.1PbTiO3 (.9PMN-.1PT) have been investigated. Ceramic targets of 0.9PMN-0.1PT with and without excess PbO were used for thin film deposition and were grown on substrates of SrTiO3 LaAlO3, MgO, and Pt\\/TiO2\\/SiO2\\/Si using pulsed laser ablation deposition. It was shown that the phase purity of the films was dependent on the

S. K. Singh; P. Bhattacharya; P. A. Thomas; S. B. Palmer

2002-01-01

96

Fabrication and characterization of relaxor ferroelectric PbFe1/2Ta1/2O3 thin film: A comparison with ceramics  

NASA Astrophysics Data System (ADS)

Highly oriented Pb(Fe1/2Ta1/2)O3 (PFT) film is fabricated on conducting La0.67Sr0.33CoO3 coated (100) MgO substrate using pulsed laser deposition technique. The x-ray diffraction pattern shows single phase compound having preferential orientation along (100) plane. Surface topography of the film indicates homogeneous distribution of grains with an average grain size ~55 nm. Broad dielectric dispersion, high dielectric diffusivity, and moderate dielectric loss are observed in the vicinity of wide range of temperatures and frequencies. A reasonably good shift in dielectric maximum temperature (~30 K) is observed from 1 to 500 kHz suggests relaxor nature of film in this frequency range. At the same time, diffuse dielectric dispersion is seen above 500 kHz indicating diffuse ferroelectric phase transition. Dielectric data fallows the nonlinear Vogel-Fulcher relation below 500 kHz applied frequency which support the relaxor nature of PFT film. The ferroelectric hysteresis loop and butterfly loop show well defined saturated loop below freezing temperature (Tf) (~150 K). A large shift in dielectric maximum temperature (Tm), i.e., around 75 K is observed compared to bulk counterpart that may be due to misfit strain across substrate-bottom electrode-film interface and in plane compressive strain in the film.

Martínez v, R.; Kumar, Ashok; Sanchez, Dilsom A.; Palai, R.; Katiyar, R. S.

2010-10-01

97

Theoretical and experimental investigation of Raman modes, ferroelectric and dielectric properties of relaxor Na0.5Bi0.5TiO3  

NASA Astrophysics Data System (ADS)

We use a combination of first-principles density functional theoretical analysis and experimental characterization to understand the lattice dynamics, dielectric and ferroelectric properties of lead-free relaxor ferroelectric Na0.5Bi0.5TiO3 (NBT) system. Vibrational spectrum determined through our calculations agrees well with the observed Raman spectrum, and allows assignment of symmetry labels to modes. The calculated Born effective charges reveal (a) two distinct types of Ti ions at the B-site with anomalous dynamical charges differing by up 1.6e, and (b) Na and Bi ions at the A-site exhibit disparate dynamical charges of about 1 and 5.5e, respectively. Thus, there exist hetero-polar activity at both A and B-sites in NBT, and disorder associated with these hetero-polar ions is responsible for its relaxor behaviour. Large dielectric response of NBT arises primarily from phonons, and specifically the modes involving Bi-O (109 cm-1) and Ti-O (246, 276 cm-1) vibrations, respectively.

Niranjan, Manish K.; Karthik, T.; Asthana, Saket; Pan, Jaysree; Waghmare, Umesh V.

2013-05-01

98

Relaxor ferroelectricity and the freezing of short-range polar order in magnetite  

NASA Astrophysics Data System (ADS)

A thorough investigation of single-crystalline magnetite using broadband dielectric spectroscopy and other methods provides evidence for relaxorlike polar order in Fe3O4. We find long-range ferroelectric order to be impeded by the continuous freezing of polar degrees of freedom and the formation of a tunneling-dominated glasslike state at low temperatures. This also explains the lack of clear evidence for a noncentrosymmetric crystal structure below the Verwey transition. Within the framework of recent models assuming an intimate relation of charge and polar order, the charge order, too, can be speculated to be of short-range type only and to be dominated by tunneling at low temperatures.

Schrettle, F.; Krohns, S.; Lunkenheimer, P.; Brabers, V. A. M.; Loidl, A.

2011-05-01

99

High-temperature structural transformations in the relaxor ferroelectrics PbSc{sub 0.5}Ta{sub 0.5}O{sub 3} and Pb{sub 0.78}Ba{sub 0.22}Sc{sub 0.5}Ta{sub 0.5}O{sub 3}  

SciTech Connect

Temperature-driven structural transformations in Pb-based perovskite-type relaxors are studied by using polarized Raman spectroscopy, high-resolution powder, and synchrotron single-crystal x-ray diffraction applied to PbSc{sub 0.5}Ta{sub 0.5}O{sub 3} (PST) and Pb{sub 0.78}Ba{sub 0.22}Sc{sub 0.5}Ta{sub 0.5}O{sub 3} (PBST). The two compounds were chosen as model systems because PST is a relaxor that exhibits ferroelectric long-range order on cooling, whereas PBST shows canonical relaxor behavior. The temperature evolution of phonon anomalies and the pseudocubic unit-cell parameter for both PST and PBST reveals the existence of a characteristic temperature T* between the Burns temperature T{sub B} and the temperature of the dielectric-permittivity maximum T{sub m}. T* is associated with the coupling of initially nucleated small polar clusters and their aggregation into larger polar clusters. The temperature range between T{sub B} and T* is characterized by a coupling between adjacent off-centered BO{sub 6} octahedra to form initial polar clusters, while the range between T* and T{sub m} is characterized by a coupling between off-centered B cations from adjacent polar clusters. Off-centered Pb atoms exist even above the Burns temperature and their length of coherence governs the coupling between polar regions comprising B-cation off-center shifts and, consequently, directs the formation of the ferroelectric state to a normal, long-range ordered or nonergodic relaxor state.

Mihailova, B.; Maier, B.; Paulmann, C.; Malcherek, T.; Bismayer, U. [Mineralogisch-Petrographisches Institut, Universitaet Hamburg, Grindelallee 48, D-20146 Hamburg (Germany); Ihringer, J. [Institut fuer Angewandte Physik, Universitaet Tuebingen, Auf der Morgenstelle 10, 72076 Tuebingen (Germany); Gospodinov, M. [Institute of Solid State Physics, Bulgarian Academy of Sciences, Boulevard Tzarigradsko Chausse 72, 1784 Sofia (Bulgaria); Stosch, R.; Guettler, B. [Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig (Germany)

2008-05-01

100

High energy-storage performance in Pb0.91La0.09(Ti0.65Zr0.35)O3 relaxor ferroelectric thin films  

NASA Astrophysics Data System (ADS)

In this work, 1-?m-thick relaxor ferroelectric (FE) films with a typical composition of Pb0.91La0.09(Ti0.65Zr0.35)O3 (PLZT 9/65/35) were successfully deposited on platinum-buffered silicon substrates via a sol-gel technique. The microstructure, electrical properties, and energy-storage performance of the obtained thin films were investigated in detail. X-ray diffraction (XRD) analysis and field-emission scanning electron microscopy pictures indicated that the crystallized thin films showed a random orientation with uniform and dense microstructure. Electrical measurements illustrated that the relaxor FE thin films had a considerable capacitance density of 925 nF/cm2 at 1 MHz and a higher critical breakdown field of 2177 kV/cm. As a result, a large recoverable energy-storage density of 28.7 J/cm3 was obtained in the thin films at room temperature. Moreover, good charge-discharge endurance was also realized in the FE films, confirmed by the repeated polarization-electric field loops.

Hao, Xihong; Wang, Ying; Yang, Jichun; An, Shengli; Xu, Jinbao

2012-12-01

101

Development of nanoscale polarization fluctuations in relaxor-based (1-x)Pb(Zn1/3Nb2/3)O3-xPbTiO3 ferroelectrics studied by Brillouin scattering  

NASA Astrophysics Data System (ADS)

The precursor dynamics of ferroelectric phase transitions in relaxor-based ferroelectric (1-x)Pb(Zn1/3Nb2/3)O3-xPbTiO3 single crystals, with x=0.07, 0.10, and 0.12, were investigated using inelastic light scattering from a longitudinal acoustic phonon. An acoustic anomaly in a broad temperature range, which is characteristic of relaxor ferroelectrics, was observed. We describe the anomalies in the paraelectric phase by assuming local piezoelectric coupling inside polar nanoregions, which are surrounded by a nonpolar matrix. On the basis of local piezoelectric coupling, a relaxation time ? and a dynamic characteristic length L of the order-parameter (polarization) fluctuations were determined to be in the order of 10-13 s and 10-9 m, respectively. The ? and L values increase sharply upon cooling from high temperatures but more gradually below the intermediate temperature T* (=493-510K). This result implies that the local polarization fluctuations grow rapidly upon cooling down to above T* and the growth rate decreases below T*. The inflexion point of this growth process in the paraelectric phase is related to the characteristic properties of relaxor-based solid solutions.

Tsukada, Shinya; Hidaka, Yuki; Kojima, Seiji; Bokov, Alexei A.; Ye, Zuo-Guang

2013-01-01

102

Frequency and temperature dependence of actuating performance of Bi1/2Na1/2TiO3-BaTiO3 based relaxor/ferroelectric composites  

NASA Astrophysics Data System (ADS)

Recently, composites of relaxors (matrix) and either ferroelectric or nonergodic relaxor (seed) were proposed as a solution to resolving one of the main drawbacks of incipient piezoceramics, namely the requirement for high driving electric fields. In this study, we investigate the temperature and frequency dependence of the actuating performance of Bi1/2Na1/2TiO3-BaTiO3-based composites. Apart from the reduction of driving field, the composite architecture offers an extra degree of freedom for tailoring the temperature stability for different operational conditions for actuators. High strain values appear to be sensitive especially to driving frequency. This is originated by the time-dependent process of the coalescence of polar nanoregions. In effect, proximity of driving field and poling field leads to high strain sensitivity. Hence, the driving electric field needs to be adjusted in order to meet the desired frequency specifications for given applications.

Groh, Claudia; Jo, Wook; Rödel, Jürgen

2014-06-01

103

A constitutive model for temperature dependent behavior of ferroelectric materials  

NASA Astrophysics Data System (ADS)

A simple constitutive model for temperature dependent behavior of ferroelectric materials is developed. This model is based on the one-dimensional phase transformation model of shape memory alloys. To model the temperature dependent behavior of the ferroelectric materials, a paraelectric phase is considered in addition to four ferroelectric variants in a ferroelectric phase. These ferroelectric variants are connected in series to each other, whereas the paraelectric phase is connected in parallel to the ferroelectric phase. The internal stress is induced in the material due to this parallel connection, which increases or decreases the driving energy for the switching depending on the switching direction. As the temperature increases up to the Curie temperature, the volume fraction of the paraelectric phase is assumed to increase and the required switching energy is assumed to decrease as observed in experiments. The temperature dependence of the relationships among the electric field, electric displacement, stress, and strain are simulated and compared with published experimental data for a soft PZT. The comparison indicates that the present constitutive model can predict the temperature dependent behavior well. This implies that the proposed model can provide a convenient tool to understand the physical mechanism of the ferroelectric materials and to design smart structures containing the ferroelectric materials.

Yoshida, Keigo; Ikeda, Tadashige; Ueda, Tetsuhiko

2009-03-01

104

Relaxor ferroelectric characteristics of Ba5LaTi3Nb7O30 tungsten bronze ceramics  

NASA Astrophysics Data System (ADS)

Ba5LaTi3Nb7O30 tungsten-bronze ferroelectric ceramics were synthesized and characterized. The tetragonal tungsten bronze structure in space group P4/mbm was confirmed, and a broad permittivity peak with strong frequency dispersion was observed around 250 K where the peak points well fitted the Vogel-Fulcher relationship [H. Vogel, Phys. Zeit. 22, 645 (1921); G. S. Fulcher, J. Am. Ceram. Soc. 8, 339 (1925)]. The temperature dependence of the ferroelectric hysteresis indicated the paraelectric to ferroelectric phase transition in the temperature range between 153 and 273 K. The high temperature permittivity curve deviated from the Curie-Weiss law in quite a narrow temperature region above Tmax, which reflected the weak correlations between the polar nanoregions. The Curie-Weiss constant (C) was 1.218 × 105 K, which was consistent with that for the displacive type ferroelectric. No DSC peak was detected over the temperature region investigated here. Moreover, the Curie-Weiss constant below Tmax (C') was just two times of C, and the second order phase transition was confirmed for Ba5LaTi3Nb7O30.

Li, Kun; Li Zhu, Xiao; Qiang Liu, Xiao; Ming Chen, Xiang

2012-01-01

105

Analysis of polarization behavior in relaxation of BaTiO3-based ferroelectrics using wideband dielectric spectroscopy  

Microsoft Academic Search

Wideband dielectric spectra from the kilohertz to terahertz range are discussed for BaTiO3-based ferroelectrics. Ceramics of BaTiO3 (BT), Ba0.6Sr0.4TiO3 (BST-0.6), and BaZr0.25Ti0.75O3 (BZT-0.25) were selected as normal ferroelectrics, ferroelectrics with diffuse phase transition (DPT ferroelectrics), and relaxor ferroelectrics, respectively. The variation of ionic polarization in both BT and BST-0.6 ceramics with temperature could be explained by the softening of the

Takashi Teranishi; Takuya Hoshina; Hiroaki Takeda; Takaaki Tsurumi

2010-01-01

106

Chemical approach to neutral–ionic valence instability, quantum phase transition, and relaxor ferroelectricity in organic charge-transfer complexes  

Microsoft Academic Search

Neutral–ionic (NI) phase transition is a reversible switching of organic charge-transfer complexes between distinct valence states by external stimuli. This phase transformation in the low-dimensional system is demonstrated to provide a variety of novel dielectric, structural, and electronic properties. Importantly, ionization of the electron donor–acceptor pairs is usually accompanied by a ferroelectric or antiferroelectric order of the molecular lattice, leading

Sachio Horiuchi; Reiji Kumai; Yoichi Okimoto; Yoshinori Tokura

2006-01-01

107

Effect of La doping on the ferroic order in Pb-based perovskite-type relaxor ferroelectrics  

NASA Astrophysics Data System (ADS)

The structural alteration induced by the substitution of three-valent cations with an isotropic electronic outermost shell for Pb2+ in perovskite-type relaxors was investigated in the solid solutions Pb1-xLaxSc(1+x)/2Ta(1-x)/2O3, x =0.08 (PST-La) and Pb1-xLaxSc(1+x)/2Nb(1-x)/2O3, x =0.23 (PSN-La). In order to distinguish the “charge” effects from “strain” effects associated with the incorporation of La3+ in the structure, Sr-containing PbSc0.5Nb0.5O3 was characterized as well. The structure of the compounds was analyzed by in situ Raman spectroscopy, single-crystal x-ray diffraction, and powder neutron diffraction at different temperatures or pressures. It is shown that the embedding of La3+ strongly affects the ferroic structural species due to strain effects through a disturbance of the system of lone-pair electrons associated with Pb2+ and a decrease in the tolerance factor. La doping suppresses the dynamical coupling between off-centered Pb and B-site cations and enhances antiphase BO6 octahedral tilting which, depending on the level of doping, may lead to long-range order of antiphase BO6 tilts at ambient conditions and frustrated antiferroelectric order of Pb ions at low temperatures.

Maier, B. J.; Welsch, A.-M.; Mihailova, B.; Angel, R. J.; Zhao, J.; Paulmann, C.; Engel, J. M.; Marshall, W. G.; Gospodinov, M.; Petrova, D.; Bismayer, U.

2011-04-01

108

2-2 composites based on [011]-poled relaxor-ferroelectric single crystals: from the piezoelectric anisotropy to the hydrostatic response  

NASA Astrophysics Data System (ADS)

In this paper effect of the orientation of the main crystallographic axes on the piezoelectric anisotropy and hydrostatic parameters of 2-2 parallel-connected single crystal (SC) / auxetic polymer composites is analysed. SCs are chosen among the perovskite-type relaxor-ferroelectric solid solutions of (1 - x)Pb(Zn1/3Nb2/3)O3-xPbTiO3 and xPb(In1/2Nb1/2)O3-yPb(Mg1/3Nb2/3)O3-(1 - x - y)PbTiO3. The SC layers in a composite sample are poled along the perovskite unit-cell [011] direction and characterised by mm2 symmetry. The orientation of the main crystallographic axes in the SC layer is observed to strongly influence the effective piezoelectric coefficients d*3j, g*3j, squared figured of merit d*3j g*3j, electromechanical coupling factors k*3j (j = 1, 2 and 3), and hydrostatic analogs of these parameters of the 2-2 composite. A comparison of values of d*3j g*3j was first carried out at d*31 ? d*32 in a wide range of orientations and volume-fraction. Large values of the effective parameters and inequalities | d*33 / d*3f | > 5 and | k*33 / k*3f | > 5 (f = 1 and 2) are achieved at specific orientations of the main crystallographic axes due to the anisotropy of elastic and piezoelectric properties of the SC component. The use of an auxetic polyethylene with a negative Poisson's ratio leads to a significant increase in the hydrostatic parameters of the 2-2 composite. Particular advantages of the studied composites over the conventional ceramic / polymer composites are taken into account for transducer, hydroacoustic and energyharvesting applications.

Bowen, C. R.; Topolov, V. Y.; Betts, D. N.; Kim, H. A.

2013-05-01

109

Nanostructure and Defect Chemistry of Relaxor Ferro Electrics.  

National Technical Information Service (NTIS)

This report describes an investigation of the microstructure, microchemistry, and dielectric properties of relaxor ferroelectrics and structurally related compounds. The emphasis has been on the use of transmission electron microscopy to correlate changes...

D. M. Smyth M. P. Harmer

1988-01-01

110

Magnetic field dependent ferroelectric like behavior in glass  

Microsoft Academic Search

Lines first proposed the possibility of ferroelectricity (FE) in glass polar or nonpolar medium. However, so far no such material has been developed showing FE in glass. We developed some novel rare earth oxide (˜0.4 mol%) : SiO2 glasses which show FE like behavior (with FE loop and Curie Weiss behavior) around ambient temperature. The observed colossal dielectric constant depends

S. Mukherjee; C. H. Chen; C. C. Chou; H. D. Yang; B. K. Chaudhuri

2010-01-01

111

Local Polarization Dynamics and Bias-Induced Phase Transitions in Ferroelectric Relaxors: Time-resolved Spectroscopy and Ergodic Gap Mapping  

NASA Astrophysics Data System (ADS)

Mesoscopic domain structure and dynamics in PMN-PT solis solutions is studied using spatially resolved time- and voltage spectroscopic imaging modes. For compositions close to the MPB, we observe the formation of classical ferroelectric domains with rough self-affine boundaries. In the ergodic phase (PMN and PMN-10PT), the formation of non-classical labyrinthine domain patterns characterized by a single characteristic length scale is observed. The (a) persistence of these patterns well above Tc and (b) the fact that cannot be switched by tip bias suggest that they can be attributed to the frozen polarization component. Spatial variability of polarization relaxation dynamics in PMN-10PT is studied. Local relaxation attributed to the reorientation of polar nanoregions was found to follow stretched exponential dependence, with ? 0.4, much larger than the macroscopic value determined from dielectric spectra (? 0.09). The spatial inhomogeneity of relaxation time distribution with the presence of 100-200 nm ``fast'' and ``slow'' regions is observed. The results are analyzed to map the Vogel-Fulcher temperatures on the nanoscale. The applicability of this technique to map ``ergodic gap'' distribution on the surface is discussed. Research supported by the Division of Materials Science and Engineering, Basic Energy Sciences, U.S. Department of Energy at Oak Ridge National Laboratory, which is managed by UT-Battelle, LLC.

Kalinin, S. V.; Rodriguez, B.; Nikiforov, M. P.; Balke, N.; Jesse, S.; Ovchinnikov, O. S.; Bokov, A. A.; Ye, Z.-G.

2009-03-01

112

Dielectric and ferroelectric properties of lead indium niobate ceramic prepared by wolframite method  

Microsoft Academic Search

The dielectric and ferroelectric properties of lead indium niobate (Pb(In1\\/2Nb1\\/2)O3, PIN) ceramic prepared by an oxide-mixing method via wolframite route were investigated. The 98.5% perovskite fine-grained PIN ceramics with average grain sizes of 1–2?m were obtained by sintering at 1050°C for 2h. The dielectric properties of the PIN were of relaxor ferroelectric behavior with temperature of dielectric maximum (Tm) ?

S. Wongsaenmai; S. Ananta; X. Tan; R. Yimnirun

2008-01-01

113

Random local strain effects in homovalent-substituted relaxor ferroelectrics: A first-principles study of BaTi0.74Zr0.26O3  

NASA Astrophysics Data System (ADS)

We present first-principles supercell calculations on BaTi0.74Zr0.26O3 , a prototype material for relaxors with a homovalent substitution. From a statistical analysis of relaxed structures, we give evidence for four types of Ti-atom polar displacements: along the ?111? , ?110? , or ?100? directions of the cubic unit cell or almost canceled. The type of a Ti displacement is entirely determined by the Ti/Zr distribution in the adjacent unit cells. The underlying mechanism involves local strain effects that ensue from the difference in size between the Ti4+ and Zr4+ cations. These results shed light on the structural mechanisms that lead to disordered Ti displacements in BaTi1-xZrxO3 relaxors, and probably in other BaTiO3 -based relaxors with homovalent substitution.

Laulhé, C.; Pasturel, A.; Hippert, F.; Kreisel, J.

2010-10-01

114

Surface Acoustic Wave Propagation in Relaxor-Based Ferroelectric Single Crystals 0.93Pb(Zn1/3Nb2/3)O3-0.07PbTiO3 Poled along [011]c  

NASA Astrophysics Data System (ADS)

Surface acoustic wave (SAW) propagation in relaxor-based ferroelectric single crystals 0.93Pb(Zn1/3Nb2/3)O3-0.07PbTiO3 (PZN-7%PT) poled along [011]c has been analyzed theoretically. The results show that PZN-7%PT single crystals have excellent SAW properties, such as low phase velocities, very high electromechanical coupling coefficients and small power flow angles. It is also found that the SAW properties strongly depend on the propagation direction and the characteristic curves of SAW phase velocity, and the electromechanical coupling coefficients are symmetric with respect to ? = 90°. Considering all related factors, the X-cut PZN-7%PT single crystal has the best performance. Based on our results, the X-cut PZN-7%PT single crystals poled along [011]c are an excellent candidate for ultra-wide bandwidth low-frequency SAW devices.

Li, Xiu-Ming; Zhang, Rui; Huang, Nai-Xing; Lü, Tian-Quan; Cao, Wen-Wu

2012-02-01

115

Experimental Study of Polarization Clusters in 0.72Pb(Mg1/3Nb2/3)O3-0.28PbTiO3 Relaxor Ferroelectrics by means of Synchrotron Radiation X-ray Diffraction  

SciTech Connect

X-ray diffraction has been conducted to study the microscopic-scale structures for 0.72Pb(Mg1/3Nb2/3)O3-0.28PbTiO3 relaxor ferroelectrics in a high external DC field during phase transition. Clear quasi-periodic structures were observed along <111> and <1-11> directions near Tc induced by the high external DC field. The formation of these periodic structures are interpreted as a type of Coulomb interaction among adjacent polar clusters. The cluster size was estimated to be 17nm. It was also found that the dominating interaction direction among clusters (periodic direction) were changeable among <111> and <1-11> as temperature changed.

Guo Zhi; Tai Renzhong; Xu Hongjie [Shanghai Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, P.O. Box 800-204, Shanghai 201800 (China); Gao Chen; Pan Guoqiang; Hu Chuansheng; Fan Rong; Li Ruipeng [National Synchrotron Radiation Laboratory, University of Sciences and Technology of China, Hefei 230029 (China); Luo Haosu; Lin Di [Shanghai Institute of Ceramics, Chinese Academy of Sciences, Dingxi road 1295, Shanghai 200050 (China); Namikawa, Kazumichi [Department of Physics, Tokyo Gakugei University, 4-1-1 Nukui-Kita Machi, Kogannei-Shi, Tokyo 184-8501 (Japan)

2007-01-19

116

Origin of large recoverable strain in 0.94(Bi0.5Na0.5)TiO3-0.06BaTiO3 near the ferroelectric-relaxor transition  

NASA Astrophysics Data System (ADS)

Piezoceramics of composition 0.94(Bi0.5Na0.5)TiO3-0.06BaTiO3 demonstrate large recoverable strain at elevated temperature (T > 75 °C), which is absent at room temperature. In situ neutron diffraction was used to measure changes in the crystallographic and domain structures during electric field application at temperatures ranging from 25 °C to 100 °C. Quantitative evaluation of the ferroelastic domain volume fraction in the field-induced phases enabled calculation of the strain contribution from non-180° domain switching. The large recoverable strain is shown to be associated with the reversible nature of the phase transformation. These findings have implications to additional BNT-xBT-based composition and other relaxor ferroelectrics.

Simons, Hugh; Daniels, John E.; Glaum, Julia; Studer, Andrew J.; Jones, Jacob L.; Hoffman, Mark

2013-02-01

117

Collective dynamics underpins Rayleigh behavior in disordered polycrystalline ferroelectrics  

PubMed Central

Nanoscale and mesoscopic disorder and associated local hysteretic responses underpin the unique properties of spin and cluster glasses, phase-separated oxides, polycrystalline ferroelectrics, and ferromagnets alike. Despite the rich history of the field, the relationship between the statistical descriptors of hysteresis behavior such as Preisach density, and micro and nanostructure has remained elusive. By using polycrystalline ferroelectric capacitors as a model system, we now report quantitative nonlinearity measurements in 0.025–1 ?m3 volumes, approximately 106 times smaller than previously possible. We discover that the onset of nonlinear behavior with thickness proceeds through formation and increase of areal density of micron-scale regions with large nonlinear response embedded in a more weakly nonlinear matrix. This observation indicates that large-scale collective domain wall dynamics, as opposed to motion of noninteracting walls, underpins Rayleigh behavior in disordered ferroelectrics. The measurements provide evidence for the existence and extent of the domain avalanches in ferroelectric materials, forcing us to rethink 100-year old paradigms.

Bintachitt, P.; Jesse, S.; Damjanovic, D.; Han, Y.; Reaney, I. M.; Trolier-McKinstry, S.; Kalinin, S. V.

2010-01-01

118

Electric-field-induced local structural phenomena in relaxor ferroelectric PbSc0.5Nb0.5O3 near the intermediate temperature T* studied by Raman spectroscopy.  

PubMed

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

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

2014-04-30

119

Electric-field-induced local structural phenomena in relaxor ferroelectric PbSc0.5Nb0.5O3 near the intermediate temperature T* studied by Raman spectroscopy  

NASA Astrophysics Data System (ADS)

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 Pb2+ cations, within the system of off-centred B-site cations as well as between off-centred Pb2+ and B-site cations. The strong AFE-type coupling between Pb2+ 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.

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

2014-04-01

120

Domain structures and dielectric properties resulting from tweed precursors of relaxor ferroelectric solid-solution single-crystal 24Pb(In1/2Nb1/2)O3-46Pb (Mg1/3Nb2/3)O3-30PbTio3.  

PubMed

The domain structures of poled and depoled lead-based relaxor ferroelectric solid-solution single-crystal 24Pb(In(1/2)Nb(1/2))O(3)-46Pb (Mg(1/3)Nb(2/3))O(3)-30PbTio(3) are studied by polarized light microscopy, piezoresponse force microscopy (PFM), scanning electron microscopy (SEM), and dielectric spectroscopy. The domain structures in the nonergodic relaxor state are found by PFM to consist of tweed structures resulting from random fields from the competition between ferroelectric and antiferroelectric distortion, and planar defects found by SEM are treated as dislocations associated with strain accommodation, resulting in superior piezoelectric properties. This domain structure is found to be connected with hierarchical domain structures. PMID:23007761

Yasuda, Naohiko; Nur Hidayah, Z A; Ohwa, Hidehiro; Tachi, Yoshihito; Yamashita, Yohachi

2012-09-01

121

Behavior of highly deformable relaxor-ferroelectric-based ceramics in an electric field  

NASA Astrophysics Data System (ADS)

The deformation characteristics of multicomponent barium-doped piezoelectric ceramics mPbMg1/3Nb2/3O3- n PbNi1/3Nb2/3O3- y PbZn1/3Nb2/3O3- x PbTiO3 are studied in electric fields E = 0-12 kV/cm. Anomalies are detected in the dependences of elastic strain ?3 and piezoelectric modulus d {33/eff} on the external dc electric field. The history of the materials is shown to affect the change of piezoelectric modulus d {33/eff} in an electric field. The revealed dependences are used to propose a method to increase the efficiency of operation of piezoelectric actuators.

Talanov, M. V.; Reznichenko, L. A.

2013-10-01

122

Low temperature anomalous field effect in SrxBa1-xNb2O6 uniaxial relaxor ferroelectric seen via acoustic emission  

NASA Astrophysics Data System (ADS)

Sr0.75Ba0.25Nb2O6 [100]-oriented uniaxial tungsten bronze relaxor crystals have been studied by means of dedicated acoustic emission during their thermal cycling in 150-300 K temperature range under dc electric field (E). A 1st order transition in a modulated incommensurate tetragonal phase has been successfully detected at Tmi = 198 K on heating and Tmi = 184 K on cooling, respectively. As field E enhances, a thermal hysteresis gradually narrows and vanishes in the critical point at Eth = 0.31 kV/cm, above which a phase transition becomes to 2nd order. The Tmi(E) dependence looks as a V-shape dip, not similar that previously has been looked as a smeared minimum between both the two polar and nonpolar tetragonal phases near Tm = 220 ÷ 230 K in the same crystals (Dul'kin et al., J Appl. Phys. 110, 044106 (2011)). Due to such a V-shape dip is characteristic for Pb-based multiaxial perovskite relaxor, a rhombohedral phase is waited to be induced by a field E in the critical point temperature range. The emergence of this rhombohedral phase as a crucial evidence of an orthorhombic phase presumably existing within the modulated incommensurate tetragonal phase in tungsten bronze SrxBa1-xNb2O6 relaxor is discussed.

Dul'kin, E.; Kojima, S.; Roth, M.

2012-04-01

123

Second Harmonic Generation and Polarization Microscope Observations of Quantum Relaxor Lithium Doped Potasium Tantalate  

NASA Astrophysics Data System (ADS)

Polar state in a quantum relaxor K(1-x)LixTaO3 (KLT) is investigated using second harmonic generation (SHG) and polarization microscopes. Temperature dependences of SHG image and interference color image related to birefringence are observed on three different processes (zero field heating after zero field cooling, field heating after zero field cooling, and field heating after field cooling processes). A remarkable history dependence in the T-E space which is one of the characteristic behaviors of relaxor is observed in SHG and polarization microscope observations. Ferroelectric phase transition occurs below the transition temperature Tp with tiny domain structures which is beyond the optical microscope diffraction limit. Under an electric field, these micro domain structures change to macroscopic structures. Based on these experiments, we propose a polar state model of KLT below Tp.

Yokota, Hiroko; Uesu, Yoshiaki

2008-04-01

124

Microcracking and discontinuous fast switching as acoustic emission sources in 8\\/65\\/35 and 9.5\\/65\\/35 PLZT relaxor ferroelectrics  

Microsoft Academic Search

Microcracking, discontinuous switching, crystallographic phase transformation, internal discharges or surface friction of the macroscopic sample may be acoustic emission (AE) sources in ferroelectric ceramics. To reduce the number of possible AE sources, AE measurements were performed on hot pressed pore free well polished rhombohedral lead–lanthanum–zirconate–titanate (PLZT). Microcracking is the only AE source in electrostrictive PLZT 9.5\\/65\\/35, while in ferroelectric PLZT

Doru C Lupascu

2001-01-01

125

Mechanical and Ferroelectric Behavior of PZT-Based Thin Films  

Microsoft Academic Search

The mechanical and ferroelectric behavior of freestanding lead zirconate titanate (PZT) -based thin film uni- morph structures for microelectromechanical systems was in- vestigated with uniaxial tension specimens of SiO2-TiPt-PZT-Pt, SiO2-TiPt-PZT, SiO2-TiPt, and individual SiO2 and Pt films. Full-field strains obtained with digital image correlation were used to compute the stress versus strain curves for each film combina- tion and the

Sivakumar Yagnamurthy; Ioannis Chasiotis; John Lambros; Ronald G. Polcawich; Jeffrey S. Pulskamp; Madan Dubey

2011-01-01

126

High-pressure Brillouin scattering of the single-crystal PbSc1/2Ta1/2O3 relaxor ferroelectric  

NASA Astrophysics Data System (ADS)

The effect of pressure on the acoustic modes and adiabatic elastic constants of the perovskite-type (ABO3) relaxor compound PbSc1/2Ta1/2O3 have been studied by Brillouin spectroscopy at room temperature up to 9.2 GPa. It is shown that the elastic constants are very sensitive to the pressure-induced structural transformations that were established by diffraction and Raman scattering analysis. Changes in the evolution of the pseudocubic elastic constants c11 and c44 occur at the two phase-transition pressures pc1 = 1.9 GPa and pc2 ˜ 5.5 GPa. Changes in evolution of c12 occur at the two characteristic pressures p1* = 1.2 GPa and p2* ˜ 3.0 GPa, which mark changes in the local structure that precede the corresponding phase transitions. The elastic anisotropy and the width of the transverse acoustic mode increase in the pressure range between pc1 and pc2 with a maximum near p2*. A strong decrease in the Cauchy parameter is observed at pressures above p2*, which indicates an enhancement of the covalent character of chemical bonding. Increasing pressure gradually suppresses the central peak typical of the relaxor ergodic state, and the quasielastic scattering vanishes at a pressure slightly above p2*.

Marquardt, H.; Waeselmann, N.; Wehber, M.; Angel, R. J.; Gospodinov, M.; Mihailova, B.

2013-05-01

127

Large strain transduction utilizing phase transition in relaxor-ferroelectric Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 single crystals  

NASA Astrophysics Data System (ADS)

In this work, we present experimental evidence that under relatively low level drive (<0.1 MV/m) the large strain (~0.5%) associated with ferroelectric rhombohedral FR-ferroelectric orthorhombic FO phase transition in domain engineered relaxor-ferroelectric single crystals under compressive stress and bias electric field can be captured. We have demonstrated this in mechanically confined ternary Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 single crystals poised at the rhombohedral side of the morphotropic phase boundary. Experimental strain-field results, methods of mechanical confinement and drive, and a low frequency, compact, high source level sound projector design are presented. Transducers that operate on a large strain principle as a design rule will benefit from this development.

Finkel, Peter; Benjamin, Kim; Amin, Ahmed

2011-05-01

128

Ferroelectric and magnetoelectric behaviors of multiferroic BiFeO 3 and piezoelectric-magnetostrictive composites  

Microsoft Academic Search

In this paper we overview our recent work on ferroelectric and magnetoelectric coupling behaviors of multiferroic doped BiFeO3 (BFO) and piezoelectric-magnetostrictive composites. Using rapid liquid sintering method we prepare single-phase BFO ceramics\\u000a of excellent ferroelectric property. The BFO thin films on Pt-coated silicon wafers by pulsed laser deposition show large remnant polarization but serious ferroelectric switching fatigue.\\u000a A series of

J.-M. Liu; F. Gao; G. L. Yuan; Y. Wang; M. Zeng; J. G. Wan

2008-01-01

129

Raman spectroscopic studies of disordered ferroelectric oxides  

NASA Astrophysics Data System (ADS)

Relaxational properties of compositionally disordered AB03 perovskite oxides were studied. These oxides are the prototypical soft ferroelectric (FE) mode systems, and their interesting dipolar relaxational properties are determined by their long, strongly temperature-dependent correlation lengths for the dipolar interactions. The simple cases involve dilute chemical substitutions in the incipient ferroelectrics KTaO3 and SrTiO3, which exhibit relatively weak, low-temperature Debye-type relaxations. More complicated dipolar interactions are seen in B-site disordered Nb-doped KTaO3, which exhibits glass-like relaxor and relaxor-to-ferroelectric crossover behaviors at low temperatures. Finally, there is a class of more complex perovskites represented by PMN, PZN-PT and the PLT that exhibit strong, high-temperature relaxor and/or ferroelectric properties. The renewed interest in the KTa1-xNbxO (KTN) mixed perovskite materials, especially in high quality thin films, is connected with their remarkable dielectric properties in the dilute compositions. Off-center Nb ions in the highly polarizable KTaO3 lattice provide a drastic increase in the dielectric peak, up to 20 times in comparison with the pure KTaO3 and KNbO3. The effects of the substrate and the symmetry-breaking defects on their vibration spectra were studied by micro-Raman spectroscopy. An anomalous residual intensity of the forbidden first-order scattering modes in the cubic paraelectric phase of the KTN films was connected with the formation of polar microregions even far above the bulk Tc. On the whole, the KTN film behavior shows the existence of specific defects enhancing the perovskite unit cell in the film so that the activity of off-center Nb ions increases in producing larger electric dipoles and extending the precursor phase above Tc. In diluted compositions with low Nb concentrations KTN materials exhibit formation of polar nano regions and relaxor like behavior. This behavior is analogous with behavior of well know relaxor systems, such as PbMg1/3Nb2/3O3 (PMN) and Pb1-x LaxTiO3 (PLT). Raman scattering was studied in model relaxor ferroelectrics PbSc 1/2Ta1/2O3 (PST) and PMN and in related low-permittivity materials SrAl1/2Ta1/2O3 (SAT), SrAl 1/2Nb1/2O3 (SAN) and BaMg1/3Ta 2/3O3 (BMT). Comparative analysis of the Raman spectra gives evidence that complex perovskites of this type consist of nanoscale clusters with the 1:1 B-site order, irrelevant to whether a stoichiometric composition for the B cations is 1:1 or 1:2. This result is in agreement with the recent microstructure studies of both PST and PMN by direct methods. The low-permittivity compounds reveal the static basic spectrum for the corresponding 1:1 or 1:2 compositions. The basic spectrum is modified in relaxors by dynamic effects in the course of evolution to the ferroelectric state. Model relaxors PST and PMN show clearly such dynamic effects as mode broadening and a central peak. In A-site substituted complex perovskite PLT systems micro-Raman results indicate that the crystal structure of the PLT films was strongly influenced by the La contents. The dielectric properties of PLT thin films were studied in the temperature range 80--700 K and results indicate that PLT thin films undergo normal-to-relaxor ferroelectric transformation with 30 at% La content in PLT films. The observed behavior is evaluated in terms of diffuseness and Vogel-Fulcher relationship, which is typical for relaxor ferroelectrics. It is consistent with typical relaxor behavior of disordered materials with polar nanoregions.

Savvinov, Alexey A.

130

In situ high-temperature high-pressure Raman spectroscopy on single-crystal relaxor ferroelectrics PbSc1/2Ta1/2O3 and PbSc1/2Nb1/2O3  

NASA Astrophysics Data System (ADS)

The effect of temperature on the pressure-induced structural changes in perovskite-type (ABO3) relaxor ferroelectrics is studied by in situ high-temperature high-pressure Raman spectroscopy on single crystals of PbSc1/2Ta1/2O3 (PST) and PbSc1/2Nb1/2O3 (PSN), which allowed us to elucidate the interplay between the polar and antiferrodistortive order coexisting on the mesoscopic scale at ambient conditions. High-pressure experiments were carried out at elevated temperatures below and above the characteristic intermediate temperature T*. The results were compared with those obtained at room temperature, which for PST is just above the paraelectric-ferroelectric phase transition TC, whereas for PSN is below TC. It is shown that the first critical pressure pc1, at which a transition from a relaxor to a non-polar rhombohedral state with antiphase octahedral tilt ordering occurs, decreases at elevated temperatures due to the weakening of the polar coupling, which in turn facilitates the evolution of the preexisting medium-range antiferrodistortive order into a long-range order. The critical pressure pc2 of the second phase transition, involving a change in the type of the antiferrodistortive order, is not affected by temperature, i.e. it is independent of the state of polar coupling and is mainly related to the initial correlation length of antiferrodistortive order. The strong influence of temperature on pc1, which occurs only when the mesoscopic polar order is suppressed, emphasizes the importance of coexisting ferroelectric and antiferrodistortive coupling for the occurrence of the relaxor states.

Waeselmann, N.; Mihailova, B.; Gospodinov, M.; Bismayer, U.

2013-04-01

131

In situ high-temperature high-pressure Raman spectroscopy on single-crystal relaxor ferroelectrics PbSc(1/2)Ta(1/2)O3 and PbSc(1/2)Nb(1/2)O3.  

PubMed

The effect of temperature on the pressure-induced structural changes in perovskite-type (ABO3) relaxor ferroelectrics is studied by in situ high-temperature high-pressure Raman spectroscopy on single crystals of PbSc1/2Ta1/2O3 (PST) and PbSc1/2Nb1/2O3 (PSN), which allowed us to elucidate the interplay between the polar and antiferrodistortive order coexisting on the mesoscopic scale at ambient conditions. High-pressure experiments were carried out at elevated temperatures below and above the characteristic intermediate temperature T*. The results were compared with those obtained at room temperature, which for PST is just above the paraelectric-ferroelectric phase transition TC, whereas for PSN is below TC. It is shown that the first critical pressure pc1, at which a transition from a relaxor to a non-polar rhombohedral state with antiphase octahedral tilt ordering occurs, decreases at elevated temperatures due to the weakening of the polar coupling, which in turn facilitates the evolution of the preexisting medium-range antiferrodistortive order into a long-range order. The critical pressure pc2 of the second phase transition, involving a change in the type of the antiferrodistortive order, is not affected by temperature, i.e. it is independent of the state of polar coupling and is mainly related to the initial correlation length of antiferrodistortive order. The strong influence of temperature on pc1, which occurs only when the mesoscopic polar order is suppressed, emphasizes the importance of coexisting ferroelectric and antiferrodistortive coupling for the occurrence of the relaxor states. PMID:23515250

Waeselmann, N; Mihailova, B; Gospodinov, M; Bismayer, U

2013-04-17

132

Interface cofiring behaviour of multilayer devices between ferroelectric and Ag\\/Pd electrode  

Microsoft Academic Search

The study on the cofiring behavior between Pb-based relaxor ferroelectric and Ag-Pd electrodes was carried out. The results indicated evident interdiffusion and chemical reactions at the cofired interface. Except for Mg, Zn and Nb elements, Ag and Pb interfacial diffusion was considered as the root reasons for the interaction. The cofired interface between the ceramic and the Ag\\/Pd electrode was

Longtu Li; Ruzhong Zuo; Zhilun Gui

2001-01-01

133

Structural state of relaxor ferroelectrics PbSc0.5Ta0.5O3 and PbSc0.5Nb0.5O3 at high pressures up to 30 GPa  

NASA Astrophysics Data System (ADS)

The pressure-induced structural changes in perovskite-type (ABO3) Pb-based relaxor ferroelectrics are studied on the basis of in situ single-crystal synchrotron x-ray diffraction and Raman scattering experiments on PbSc0.5Ta0.5O3 and PbSc0.5Nb0.5O3 conducted under hydrostatic conditions up to 30 GPa. Complementary density functional theory calculations have been performed to compare the stability of various atomic configurations for both compounds at high pressures. By combining the experimental and theoretical results, the following sequence of structural transformations is proposed. At a characteristic pressure p1 the mesoscopic polar order is violated and a local antipolar order of Pb atoms as well as quasidynamical long-range order of antiphase octahedral tilts is developed. These structural changes facilitate the occurrence of a continuous phase transition at pc1>p1 from cubic to a nonpolar rhombohedral structure comprising antiphase octahedral tilts of equal magnitude (a-a-a-). At a characteristic pressure p2>pc1 the octahedral tilts around the cubic [100], [010], and [001] directions become different from each other on the mesoscopic scale. The latter precedes a second phase transition at pc2, which involves long-range order of Pb antipolar displacements along cubic [uv0] directions and a compatible mixed tilt system (a+b-b-) or long-range ordered antiphase tilts with unequal magnitudes (a0b-b-) without Pb displacement ordering. The phase-transition pattern at pc2 depends on the fine-scale degree of chemical B-site order in the structure.

Maier, B. J.; Waeselmann, N.; Mihailova, B.; Angel, R. J.; Ederer, C.; Paulmann, C.; Gospodinov, M.; Friedrich, A.; Bismayer, U.

2011-11-01

134

Electro-optic measurements of the ferroelectric-paraelectric boundary in Ba{sub 1-x}Sr{sub x}TiO{sub 3} materials chips  

SciTech Connect

The combinatorial material chip strategy is used to study the ferroelectric-paraelectric phase boundary of the Ba{sub 1-x}Sr{sub x}TiO{sub 3} thin film system. The electro-optic (EO) effect at different compositions is measured using a modified direct-current/alternating-current birefringence EO measurement technique. We find that Ba{sub 1-x}Sr{sub x}TiO{sub 3} thin films exhibit relaxor like behavior with diffused ferroelectric domains existing well past the previously defined ferroelectric-paraelectric boundary (x>0.3). (c) 2000 American Institute of Physics.

Li, Jingwei [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)] [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Duewer, Fred [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)] [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Gao, Chen [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)] [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Chang, Hauyee [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)] [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Xiang, X.-D. [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)] [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Lu, Yalin [NZ Applied Technologies, Corp., Woburn, Massachusetts 01801 (United States)] [NZ Applied Technologies, Corp., Woburn, Massachusetts 01801 (United States)

2000-02-07

135

Relaxor behavior, polarization buildup, and switching in nanostructured 0.92 PbZn1/3Nb2/3O3-0.08 PbTiO3 ceramics.  

PubMed

The relaxor-type behavior, electrical polarization buildup, and switching in 0.92Pb(Zn(1/3)Nb(2/3))O(3)-0.08PbTiO(3) nanostructured ceramics with a grain size of approximately 20 nm is reported for the first time. This composition presents the highest-known piezoelectric coefficients, yet phase stability is an issue. Ceramics can only be obtained by the combination of mechanosynthesis and spark-plasma sintering. The results raise the possibility of using nanoscale, perovskite-relaxor-based morphotropic-phase-boundary materials for sensing and actuation in nanoelectromechanical systems. PMID:17935067

Algueró, Miguel; Hungría, Teresa; Amorín, Harvey; Ricote, Jesús; Galy, Jean; Castro, Alicia

2007-11-01

136

Magnetic field dependent ferroelectric like behavior in glass  

NASA Astrophysics Data System (ADS)

Lines first proposed the possibility of ferroelectricity (FE) in glass polar or nonpolar medium. However, so far no such material has been developed showing FE in glass. We developed some novel rare earth oxide (˜0.4 mol%) : SiO2 glasses which show FE like behavior (with FE loop and Curie Weiss behavior) around ambient temperature. The observed colossal dielectric constant depends on magnetic and electric fields. No signature of structure was detected by XRD. However, long time annealing (˜700 ^o) small number of rare earth oxide nanoparticles (˜3 nm) appear as observed from high resolution electron micrograph but here also no sigh of crystalline peak in the XRD micrographs. We believe this is the first report supporting the possibility of FE in glass as proposed by Lines with no long range order. The origin of this dielectric instability is considered to be due to the strong coupling of the magnetic spin with the ?dielectrically soft? local O-Si-O structural unit (configuration) which causes micro- stress and an anisotropic strain developed during glass network formation with magnetic impurity ions. The stress released by annealing the glass and hence destroys the FE feature. A model with glass network structure has also been proposed.

Mukherjee, S.; Chen, C. H.; Chou, C. C.; Yang, H. D.; Chaudhuri, B. K.

2010-03-01

137

Ferroelectric Properties and Leakage Behavior in Poly (Vinylidene Fluoride-Trifluoroethylene) Ferroelectric Thin Films with Additive Diethyl Phthalate  

Microsoft Academic Search

The ferroelectric properties and leakage current behavior of poly (vinylidene fluoride-trifluoroethylene) thin films capacitors using Pt as top and bottom electrodes are reported. The poly (vinylidene fluoride-trifluoroethylene) thin films doped with diethyl phthalate were deposited on Pt\\/Ti\\/SiO2\\/Si with spin-coating method. The experimental results show that the addition of diethyl phthalate in copolymer thin films significantly improves the polarization properties and

Y. G. Xiao; M. H. Tang; H. Y. Xu; J. He

2011-01-01

138

Anomalous Behavior of Sound near the Curie Points in Displacive-Type Ferroelectrics  

Microsoft Academic Search

The dynamical behavior of the acoustic mode in displacive-type ferroelectrics such as BaTiO3 and SrTiO3 is studied theoretically. The phenomenological theory of sound attenuation near the phase transition point due to Landau and Khalatnikov is extended to the system in which kinetic energy plays an essential role, so as to be applicable to displacive-type ferroelectrics. The nature implied in the

Kensuke Tani; Naoyuki Tsuda

1969-01-01

139

Spontaneous strain and ferroelectric-ferroelastic behavior in epitaxial bismuth ferrite thin films  

NASA Astrophysics Data System (ADS)

The low symmetry and spontaneous strain inherent to all ferroelectric materials causes twinning, a commonly observed microstructural feature in ceramics and crystals of ferroelectric materials. Currently, twin boundaries in ferroelectric thin films and their effects on a variety of proposed nano-scale devices is an active area of research. In this thesis, the properties and roles of twin boundaries were investigated in ferroelectric, ferroelastic and antiferromagnetic epitaxial thin films of BiFeO3. The as-deposited thin films exhibited twin wall distortions as determined with four-circle high resolution x-ray diffraction and reciprocal space mapping. The larger twin wall distortions were linked to (1) misfit strain relaxation and (2) the bulk thermal expansion of BiFeO3. In addition, the as-deposited films were stimulated with high in-plane electric fields in order to initiate the movement of ferroelectric-ferroelastic domain walls. During and after electric field poling, twin deformation behavior was investigated macroscopically by monitoring the switching current and locally with piezoresponse force microscopy, respectively. As a result of this study, the twin wall deformation was identified and found to be highly con-elated with pinning of ferroelectric-ferroelastic domain wall propagation. These findings suggest means to reduce barriers to the polarization reversal in ferroelectric thin film devices.

Folkman, Chad M.

140

Ferroelectrics  

Microsoft Academic Search

Motivated by the observed thickness-scaling of the coercive field in ferro- electric films over five decades, we develop a statistical approach towards understanding the conceptual underpinnings of this behavior. Here the scal- ing exponent is determined by the field-dependence of a known and measured quantity, the nucleation rate per unit area. We end with a discussion of our initial assumptions

P. Chandra; M. Dawber; P. B. Littlewood; J. F. Scott

141

Role of defect distributions and mobility on ferroelectric phase transformations in lead zirconate titanate  

SciTech Connect

Studies of the influence of defect distributions and mobility on ferroelectric phase transformations in lead zirconate titanate have been performed by transmission electron microscopy, high resolution electron microscopy, polarization switching measurements, and dielectric spectroscopy. Investigations focused on La{sup 3+} and K{sup 1+} modified lead zirconate titanates. Defects which could be randomly quenched-in from temperatures significantly above that of the ferroelectric phase transformation resulted in relaxor ferroelectric behavior characterized by polar nanodomains. However, defects which remained mobile until temperatures significantly below that of the phase transformation resulted in a normal ferroelectric state which was characterized by domain pinning. Mobile impurities/vacancies are revealed to order into chain fragments or clusters which diffuse to domain boundaries resulting in a pinning of the boundaries on cooling. {copyright} {ital 1997 American Institute of Physics.}

Tan, Q.; Xu, Z.; Li, J.; Viehland, D. [Department of Materials Science and Engineering and Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States)] [Department of Materials Science and Engineering and Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States)

1997-08-01

142

Targeted basic studies of ferroelectric and ferroelastic materials for piezoelectric transducer applications  

NASA Astrophysics Data System (ADS)

The work reported covers the fifth and final year of the program of targeted basic studies of ferroelectric and ferroelastic materials for piezoelectric transducer applications. Major achievements include: the development of a physical approach to understanding active composites, leading to the development of several new families of PZT, polymer piezoelectric composites for hydrophone application. These are new advances in the phenomenology and microscopic theory of electrostriction, and the evolution of a new family of high strain ferroelectric relaxor materials for practical application. New basic understanding of the polarization mechanisms in ferroelectric relaxors has been aided by the study of order disorder of the cation arrangement in lead scandium tantalate, and the results correlate well with studies of relaxor behavior, and of shape memory effects in PLZT ceramics. Low temperature studies on pure and doped PZTs have given the first clear indication of the intrinsic (averaged) single domain in response and correlate exceedingly well with earlier phenomenological theory. Crystal growth and ceramic processing studies have developed hand in hand with program needs providing new forms of conventional materials, new grain oriented structures and single crystals.

Cross, L. E.; Newnham, R. E.; Barsch, G. R.; Biggers, J. V.

1983-03-01

143

Ferroelectric precursor behavior in PbSc0.5Ta0.5O3 detected by field-induced resonant piezoelectric spectroscopy  

NASA Astrophysics Data System (ADS)

A novel experimental technique, resonant piezoelectric spectroscopy (RPS), has been applied to investigate polar precursor effects in highly (65%) B-site ordered PbSc0.5Ta0.5O3 (PST), which undergoes a ferroelectric phase transition near 300 K. The cubic-rhombohedral transition is weakly first order, with a coexistence interval of ˜4 K, and is accompanied by a significant elastic anomaly over a wide temperature interval. Precursor polarity in the cubic phase was detected as elastic vibrations generated by local piezoelectric excitations in the frequency range 250-710 kHz. The RPS resonance frequencies follow exactly the frequencies of elastic resonances generated by conventional resonant ultrasound spectroscopy (RUS) but RPS signals disappear on heating beyond an onset temperature, Tonset, of 425 K. Differences between the RPS and RUS responses can be understood if the PST structure in the precursor regime between Tonset and the transition point, Ttrans=300 K, has locally polar symmetry even while it remains macroscopically cubic. It is proposed that this precursor behavior could involve the development of a tweed microstructure arising by coupling between strain and multiple order parameters, which can be understood from the perspective of Landau theory. As a function of temperature the transition is driven by the polar displacement P and the order parameter for cation ordering on the crystallographic B site Qod. Results in the literature show that, as a function of pressure, there is a separate instability driven by octahedral tilting for which the assigned order parameter is Q. The two mainly displacive order parameters, P and Q, are unfavorably coupled via a biquadratic term Q2P2, and complex tweedlike fluctuations in the precursor regime would be expected to combine aspects of all the order parameters. This would be different from the development of polar nanoregions, which are more usually evoked to explain relaxor ferroelectric behavior, such as occurs in PST with a lower degree of B-site order.

Aktas, Oktay; Salje, Ekhard K. H.; Crossley, Sam; Lampronti, Giulio I.; Whatmore, Roger W.; Mathur, Neil D.; Carpenter, Michael A.

2013-11-01

144

Role of point defects in bipolar fatigue behavior of Bi(Mg1/2Ti1/2)O3 modified (Bi1/2K1/2)TiO3-(Bi1/2Na1/2)TiO3 relaxor ceramics  

NASA Astrophysics Data System (ADS)

Lead-free Bi(Mg1/2Ti1/2)O3-(Bi1/2K1/2)TiO3-(Bi1/2Na1/2)TiO3 (BMT-BKT-BNT) ceramics have been shown to exhibit large electromechanical strains under high electric fields along with negligible fatigue under strong electric fields. To investigate the role of point defects on the fatigue characteristics, the composition 5BMT-40BKT-55BNT was doped to incorporate acceptor and donor defects on the A and B sites by adjusting the Bi/Na and Ti/Mg stoichiometries. All samples had pseudo-cubic symmetries based on x-ray diffraction, typical of relaxors. Dielectric measurements showed that the high and low temperature phase transitions were largely unaffected by doping. Acceptor doping resulted in the observation of a typical ferroelectric-like polarization with a remnant polarization and strain hysteresis loops with significant negative strain. Donor-doped compositions exhibited characteristics that were indicative of an ergodic relaxor phase. Fatigue measurements were carried out on all of the compositions. While the A-site acceptor-doped composition showed a small degradation in maximum strain after 106 cycles, the other compositions were essentially fatigue free. Impedance measurements were used to identify the important conduction mechanisms in these compositions. As expected, the presence of defects did not strongly influence the fatigue behavior in donor-doped compositions owing to the nature of their reversible field-induced phase transformation. Even for the acceptor-doped compositions, which had stable domains in the absence of an electric field at room temperature, there was negligible degradation in the maximum strain due to fatigue. This suggests that either the defects introduced through stoichiometric variations do not play a prominent role in fatigue in these systems or it is compensated by factors like decrease in coercive field, an increase in ergodicity, symmetry change, or other factors.

Kumar, Nitish; Ansell, Troy Y.; Cann, David P.

2014-04-01

145

Dielectric properties and aging effects of manganese modified lead iron tungstate relaxor ceramics  

SciTech Connect

Mn-doped samples were used to study the effects of Mn dopant on the dielectric properties of PFW ceramics, especially on its aging behavior, since they could add some knowledge on the role of lattice defects on the aging mechanisms of this relaxor ferroelectric. Mn doping does not cause marked changes in the maximum of permittivity ({var_epsilon}{sub rmax}), transition temperature (T{sub 0}), and diffuseness coefficient ({delta}) under the solubility limit, whereas the resistivity increases significantly with increasing the Mn content. Mn-modified PFW ceramics exhibit evident aging behavior and its level increases with the increase in Mn content. The aging shows strong dependence on the frequency and has a log-linear function of aging time. Probable lattice defects in the ceramics are discussed and it is suggested that the acceptor Mn ions are dominantly compensated by oxygen vacancies, providing reorientable dipole pairs which are responsible for the aging process of Mn-modified PFW ceramics.

Zhou, L.; Vilarinho, P.M.; Baptista, J.L. [Univ. de Aveiro (Portugal). Dept. de Engenharia Ceramica e do Vidro/INESC] [Univ. de Aveiro (Portugal). Dept. de Engenharia Ceramica e do Vidro/INESC

1996-06-01

146

Dielectric properties of metal-organic chemical vapor deposited highly textured Pb(ScTa){sub 1{minus}x}Ti{sub x}O{sub 3} (x=0{endash}0.3) relaxor ferroelectric thin films on LaNiO{sub 3} electrode buffered Si  

SciTech Connect

Highly (100) textured Pb(ScTa){sub 1{minus}x}Ti{sub x}O{sub 3} (x=0{endash}0.3) thin films were grown on LaNiO{sub 3}/Pt/Ti electrode-coated Si substrate using metal-organic chemical vapor deposition at 685thinsp{degree}C. Ti addition was introduced to modify the dielectric properties. Diffuse phase transition, typical of relaxor ferroelectrics was noticed. As Ti content increased from 0{percent} to 30{percent}, the phase transition temperature (T{sub max}) gradually shifted from {minus}10 to 120thinsp{degree}C with the dielectric constant at T{sub max} increased from 1397 to 1992 (1 kHz). Loss tangent values are generally below 0.025. {copyright} {ital 1999 American Institute of Physics.}

Lin, C.H.; Lee, S.W.; Chen, H. [Department of Materials Science and Engineering, Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States)] [Department of Materials Science and Engineering, Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Wu, T.B. [Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu, Taiwan, Republic of (China)] [Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu, Taiwan, Republic of (China)

1999-10-01

147

The intermediate temperature T* revealed in relaxor polymers  

NASA Astrophysics Data System (ADS)

The temperature dependence of the dielectric and optical properties, crystal structure, and infrared spectra of the relaxor poly(vinylidenefluoride-trifluoroethylene-chlorofluoroethylene) terpolymer films obtained from Langmuir-Blodgett method have been comprehensively investigated. All the results suggest that there exists a peculiar point at ˜370 K, which is attributed to the intermediate temperature T* recently discovered in inorganic relaxors. Here, T* results from the change in the growth rate of the trans gauche T3GT3G' chain conformations with temperature, which is similar to the transformation from dynamic to static behavior of the so-called polar nano-regions in inorganic relaxors.

Liu, B. L.; Tian, B. B.; Geiger, S.; Hu, Z. G.; Zhao, X. L.; Zou, Y. H.; Wang, J. L.; Sun, J. L.; Sun, S.; Dkhil, B.; Meng, X. J.; Chu, J. H.

2014-06-01

148

Ferroelectric Domains in SrxBa1 ? xNb2O6 Single Crystals (0.4 ? × ? 0.75)  

Microsoft Academic Search

The crossover of single crystalline SrxBa1 ? xNb2O6 (SBN) from ferroelectric to relaxor behavior when increasing the Sr content from x = 0.4 to x = 0.75 is investigated by dielectric low-frequency susceptometry and scanning piezo-force microscopy. Increasing quenched random electric fields are conjectured to be responsible for the observed increasing dielectric polydispersivity and the growing fractality of the polar

Vladimir V. Shvartsman; Jan Dec; Seweryn Miga; Tadeusz ?ukasiewicz; Wolfgang Kleemann

2008-01-01

149

Sound behavior near the Lifshitz point in proper ferroelectrics  

NASA Astrophysics Data System (ADS)

The interaction between soft optic and acoustic phonons was investigated for Sn2P2(Se0.28S0.72)6 proper uniaxial ferroelectrics by Brillouin-scattering and ultrasonic pulse-echo techniques. The elastic softening of hypersound velocity of transverse-acoustic phonons and for both longitudinal and transverse ultrasound waves which propagate near direction of the modulation wave vector (in the incommensurate phase at x>xLP ) was found at cooling to the Lifshitz point in the paraelectric phase. The strong increase in the ultrasound attenuation has also been observed. Such phenomena are related to the linear interaction of the soft optic and acoustic branches in the region of relatively short-range hypersound waves and to the strongly developed long-range order-parameter fluctuations in the ultrasound frequency range. The hypersound velocity temperature dependence was described within the Landau-Khalatnikov approximation for the ferroelectric phase.

Kohutych, A.; Yevych, R.; Perechinskii, S.; Samulionis, V.; Banys, J.; Vysochanskii, Yu.

2010-08-01

150

Ferroelectric behavior of Al substituted InP  

NASA Astrophysics Data System (ADS)

InP:Al was grown by the liquid phase epitaxy method on InP (100)substrates. X-ray diffraction confirmed the epitaxial growth along (100) of AlInP. Photoluminescence spectra showed the evident effect of Al content. Ferroelectric characterization of the sample revealed a clear hysteresis in its polarization-voltage curves. The remnant polarization of InP:Al amounts to 1.99 ?C/cm2 at 300 Hz, and it decreases with increasing temperature in a continuous and diffusive manner. Resistance measurement demonstrated a maximum resistance at 160 °C, tentatively consistent with the transition temperature of remnant polarization. The ferroelectricity is accounted by the collective interaction between nuclei having the microscopic instability from the cation size difference in InP:Al.

Park, C. S.; Lee, S. J.; Kang, T. W.; Fu, D. J.

2006-12-01

151

Ferroelectric Tunnel Junctions: Resistive Switching Behavior by Scanning Probe Microscopy  

Microsoft Academic Search

In this work, we demonstrate the reproducible tunneling electroresistance effect in ultrathin epitaxial ferroelectric heterostructures by means of scanning probe microscopy techniques. Ultrathin films of barium titanate (in the range from 2 nm to 10 nm) with microscopically patterned SrRuO3 top electrodes have been grown on the SrRuO3\\/SrTiO3 substrates by atomic-layer-controlled pulsed-laser deposition. Imaging and control of polarization state in

A. Stamm; H. Lu; D. Wu; Y. Wang; D. Felker; M. Rzchowski; H. W. Jang; C. W. Bark; C.-B. Eom; E. Y. Tsymbal; A. Gruverman

2010-01-01

152

Nanoscale piezoelectric and ferroelectric behaviors of seashell by piezoresponse force microscopy  

NASA Astrophysics Data System (ADS)

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.

Li, Tao; Zeng, Kaiyang

2013-05-01

153

Targeted basic studies of ferroelectric and ferroelastic materials for piezoelectric transducer applications  

NASA Astrophysics Data System (ADS)

The report delineates the new progress made in the fifth and final year and discusses the major accomplishments of the full five year program both in the basic science and in the spin off to practical transducer applications. Possible new areas of study which are suggested by the present studies are briefly reported. Major achievements include the development of a physical approach to understanding active composites, leading to the development of several new families of PZT:polymer piezoelectric composites for hydrophone application. New advances in the phenomenology and microscopic theory of electrostriction, and the evolution of a new family of high strain ferroelectric relaxor materials for practical application. New basic understanding of the polarization mechanisms in ferroelectric relaxors has been aided by the study of order-disorder of the cation arrangement in lead scandium tantalate, and the results correlate well with studies of relaxor behavior, and of shape memory effects in PLZT ceramics. Low temperature studies on pure and doped PZTs have given the first clear indication of the intrinsic (averaged) single domain response and correlate exceedingly well with earlier phenomenological theory. Crystal growth and ceramic processing studies have developed hand-in-hand with program needs providing new forms of conventional materials, new grain oriented structures and single crystals.

Cross, L. E.; Newnham, R. E.; Barsch, G. R.; Biggers, J. V.

1983-03-01

154

Behavior of susceptibility and polarization near a smectic-A- ferroelectric-smectic-C tricritical point  

NASA Astrophysics Data System (ADS)

A binary liquid-crystal system possessing a tricritical point in its smectic-A-ferroelectric-smectic-C phase boundary is studied. The electroclinic tilt susceptibility and the spontaneous polarization are measured on both the first-order and the second-order side of the tricritical point. The experimental results are compared with predictions of a simple Landau model Good agreement with mean-field behavior is found.

Bahr, Ch.; Heppke, G.

1990-12-01

155

An analytical axisymmetric model for the poling-history dependent behavior of ferroelectric ceramics  

NASA Astrophysics Data System (ADS)

The poling-history dependent behavior of ferroelectric ceramics has been investigated by experimental tests. A suddenly poled ferroelectric ceramic was found to have significantly larger remnant polarization and strain than the corresponding values of a gradually poled one. To explain this phenomenon, a new domain-switching criterion for ferroelectric ceramics is proposed, in which each 180° switching is divided into two successive 90° switchings. In a suddenly poled ceramic, the strong intergranular interaction after the first 90° switching is favorable for accomplishing the second 90° switching. The effects of poling-dependent effects are then taken into account by evaluating different levels of energy dissipation after the first 90° switching. The domain orientation distribution function (ODF) as well as the macroscopic polarization and strain are analytically derived under cyclic electric loading. In the non-dissipation case, the macroscopic polarization of a ferroelectric ceramic can be ideally saturated as long as the magnitude of the applied electric field exceeds \\sqrt 2 E_{\\mathrm {C}} (EC is the coercive field), while in the full dissipation case, the maximum macroscopic polarization is related to the magnitude of the applied electric field. The hysteresis loops for the non-dissipation case are almost identical to the corresponding loops of a suddenly poled ceramic, and the hysteresis loops for the full dissipation case are very close to those of a gradually poled ceramic. The good agreement between the analytical and experimental results indicates the validity of the proposed model in describing the poling-history dependent effects in ferroelectric ceramics.

Li, Fa-Xin; Fang, Dai-Ning; Soh, Ai-Kah

2004-08-01

156

High-resolution studies of domain switching behavior in nanostructured ferroelectric polymers.  

PubMed

We have demonstrated an effective electrical control of polarization in the individual crystalline nanomesas of the ferroelectric polymer, poly(vinylidene fluoride)-trifluoroethylene (PVDF-TrFE) and its relation to the polymer structure. The mechanism of polarization reversal has been investigated via sub-10 nm real space imaging of domain pattern evolution under an applied electric field. The domain switching behavior revealed in PVDF-TrFE nanomesas is drastically different from that observed in inorganic solid-state crystalline ferroelectrics. The nanoscale features of the switching process include remote domain nucleation and spatially nonuniform wall velocity. Local switching spectroscopy and domain dynamics studies relate the observed switching features to a random-bond type disorder associated with defects in conformation and molecular packing. PMID:21462936

Sharma, Pankaj; Reece, Timothy J; Ducharme, Stephen; Gruverman, Alexei

2011-05-11

157

Nanoscale studies of switching behavior of ferroelectric thin films by using piezoresponse force microscopy  

NASA Astrophysics Data System (ADS)

The work presented in this dissertation is focused on the study of ferroelectric thin films using the method of Piezo-response Force Microscopy (PFM) with several modifications specific to ferroelectrics. In this research, the main motivation is the study of polarization-reversal mechanisms for different sizes of very small-scale (0.5-5 mum size) ferroelectric capacitors in possible applications to ferroelectric random-access-memory devices (FeRAM). In order to make such FeRAM devices more competitive with other types of nonvolatile memory technologies such as phase-change random access memory (PRAM) and magneto-resistive random access memory (MRAM), etc., it is necessary to increase the integration density and therefore reduce bit-cell size. This in turn requires a detailed understanding of (and therefore studies of) the switching properties of small-scale ferroelectric capacitors at the micrometer and sub-micrometer size scale. With traditional methods such as the polarization-hysteresis-loop measurement and the transient-switching-current measurement, such switching properties at the sub-micrometer or nanometer scale are difficult to obtain. This is due to the difficulty of electrically contacting each individual capacitor and also due to the drastically reduced electric signal at such a small scale. In addition, these methods do not provide needed spatially-resolved information about local switching. By using different experimental approaches based on PFM, all of these problems were solved and now one can directly study the switching behavior of these ferroelectric capacitors (as shown in this thesis) through observing and quantifying their PFM images. Also this thesis also presents a detailed description of PFM theory as well as the modified PFM experimental setup. In this thesis we present studies of ferroelectric thin films of two different types: polycrystalline and epitaxial. Each film has a different texture and therefore different interface defects which will affect the characteristic switching behavior. It is found from these studies that for the polycrystalline PZT thin film capacitors there is a significant capacitor-size effect. In both the time-dependent and bias-dependent studies for larger-size polycrystalline PZT capacitors the switching is dominated by nucleation. For smaller-size PZT capacitors the switching is dominated by domain-wall motion. These experimental data have been fitted with two different theoretical models: the Nucleation-Limited-Switching model (NLS model) with a Lorentz distribution of the characteristic nucleation time and Kolmogorov-Avrami-Ishibashi model (KAI model). For studies of epitaxial PZT capacitors, the time-dependent switching kinetic behavior both for larger square-shape and for smaller circular-shape capacitors is also investigated. The epitaxial-capacitor-experimental data has been interpreted as due to a theoretical model based on the Kolmogorov-Avrami-Ishibashi model (KAI model). Finally a series of ultra-thin BaTiO3 films have been investigated by using PFM and conducting-AFM to study polarization-dependent resistance. In addition, several new ideas are discussed for future experiments to further extend our knowledge in this area.

Wu, Dong

158

Orientation dependence of ferroelectric behavior of BiFeO{sub 3} thin films  

SciTech Connect

Multiferroic BiFeO{sub 3} (BFO) thin films with (111), (100), (110) preferred, and random orientations were deposited by radio frequency magnetron sputtering on SrRuO{sub 3}-buffered SrTiO{sub 3}(111), SrTiO{sub 3}(100), SrTiO{sub 3}(110), and Pt(111)/Ti/SiO{sub 2}/Si(100) substrates, respectively. The orientation dependences of ferroelectric and fatigue behavior of the BFO thin films were investigated. As expected, the (111)-oriented BFO thin film exhibits the highest, giant ferroelectric polarization (2P{sub r}=196.9 muC/cm{sup 2}) at 1 kHz and room temperature using positive up negative down measurement, while the (100)-oriented BFO thin film possesses an almost fatigue-free behavior up to 5.25x10{sup 7} switching cycles when measured at 100 kHz and room temperature. The observed behavior confirms that the largest spontaneous polarization direction and the fatigue endurance are (111) and (100) for BFO thin films, respectively. Regardless of the film orientation, the charge carriers that are responsible for dielectric relaxation and conductivity are oxygen vacancies (V{sub O}) .

Wu Jiagang; Wang, John [Department of Materials Science and Engineering, Faculty of Engineering, National University of Singapore, Singapore 117574 (Singapore)

2009-11-15

159

Thermodynamic modeling of ferroelectric epitaxial films and polarization graded ferroelectrics  

Microsoft Academic Search

Thermodynamic modeling based on the Landau-Ginzburg-Devonshire theory has been performed for epitaxial ferroelectric thin films and polarization graded ferroelectrics. The aim of this thesis is to provide a fundamental and systemic understanding of the role of internal stresses in the physical properties of epitaxial ferroelectric thin films as well as an explanation for the unconventional behavior of polarization graded ferroelectrics,

Zhigang Ban

2003-01-01

160

Dielectric properties of PbNb{sub 2}O{sub 6} ferroelectric ceramics at cryogenic temperatures  

SciTech Connect

Complex dielectric permittivity measurements in PbNb{sub 2}O{sub 6} ceramics were performed in a frequency and temperature range of 1 kHz-1 MHz and from 15 to 900 K, respectively. The results revealed two dielectric anomalies showing typical characteristics of relaxor ferroelectric materials at cryogenic temperatures. Comparison with other tetragonal tungsten bronze (TTB) structure-type materials suggests the existence of successive phase transitions, which until now were not reported. The observed low temperature dielectric behaviors seem to be due to intrinsic physical characteristics related to the TTB structure.

Guerra, J. de los S; Venet, M.; Garcia, D.; Eiras, J. A.; Guerrero, F. [Grupo de Ceramicas Ferroeletricas, Departamento de Fisica, Universidade Federal de Sao Carlos, CEP 13565-905, Sao Carlos, Sao Paulo 15385000 (Brazil); Facultad de Ciencias Naturales, Departamento de Fisica, Universidad de Oriente, C.P. 90500 Santiago de Cuba (Cuba)

2007-08-06

161

Structure and Relaxor Behaviour of Ba2+ Substituted NBT Ceramics  

NASA Astrophysics Data System (ADS)

In the course of search for environmental-friendly lead-free relaxor ferroelectrics, (Bi,Na)TiO3-(NBT) based ceramics show very good physical properties among several lead-free compositions. The NBT composition exhibits a strong ferroelectricity and high Curie temperature, and considered to be a good candidate for lead-free ceramics as a substitute for lead-based materials (e.g., PZT). In the present communication barium substituted NBT, (Na0.5Bi0.5)0.912Ba0.088TiO3-0.088BNBT composition has been prepared by conventional solid-state reaction process. The tolerance factor has been estimated and found to be 0.819, indicating the stability of the perovskite structure. The XRD analysis of the material revealed a pure perovskite with tetragonal structure. The average grain size as observed from SEM, was found to be 1.04?m. Detailed studies exhibit a relaxor behaviour with diffuse phase transition. The diffuseness parameter has been established to be 1.97. The dielectric relaxation obeyed the Vogel-Fulcher (V-F) relation. From the V-F plot, the obtained values are Tf = 305°C, Ea = 0.0131eV and ?o = 2.95×105 Hz, which provide the evidence of relaxor behaviour. The electrical behaviour has been probed through complex impedance spectroscopy. The frequency-dependent conductivity spectra obey the power law in the frequency range of 45Hz-5MHz and temperature range of 35 °C-60 °C.

Rao, K. Sambasiva; Tilak, B.; Rajulu, K. Ch. Varada; Swathi, A.; Workineh, Haileeyesus; Ganagadharudu, D.

2011-11-01

162

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

NASA Astrophysics Data System (ADS)

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 switching and nucleation behavior. Rather, the observed evolution of switching properties is a geometric effect of the heterointerface on the signal generation volume in PFM. This implies that the heterostructures can be successfully used in devices, since interfaces do not act as preferential sites for switching. At the same time, small systematic variations of switching properties within the ferroelectric component can be ascribed to the long-range elastic and electrostatic fields in the heterostructure, which can be visualized in 2D.

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

2007-10-01

163

Light scattering from (K0.5Na0.5)0.2(Sr0.75Ba0.25)0.9Nb2O6 with the tungsten bronze structure: An analogy with relaxor ferroelectrics  

Microsoft Academic Search

The Brillouin and Raman scattering from a complex single crystal from the tungsten-bronze family, (K0.5Na0.5)0.2(Sr0.75Ba0.25)0.9Nb2O6 doped with Cu2+ (KNSBN:Cu), have been comparatively studied in a wide temperature range around the ferroelectric transition. Step-like anomalies in hypersonic velocity and damping confirm the first-order structural transition. These anomalies look like some perturbations on the high-temperature slopes of both a broad dip in

I. G. Siny; S. G. Lushnikov; S. I. Siny; V. H. Schmidt; A. A. Savvinov; R. S. Katiyar

2001-01-01

164

Light scattering from (K0.5Na0.5)0.2(Sr0.75Ba0.25)0.9Nb2O6 with the tungsten bronze structure: An analogy with relaxor ferroelectrics  

Microsoft Academic Search

The Brillouin and Raman scattering from a complex single crystal from the tungsten–bronze family, (K0.5Na0.5)0.2(Sr0.75Ba0.25)0.9Nb2O6 doped with Cu2+ (KNSBN:Cu), have been comparatively studied in a wide temperature range around the ferroelectric transition. Step-like anomalies in hypersonic velocity and damping confirm the first-order structural transition. These anomalies look like some perturbations on the high-temperature slopes of both a broad dip in

I. G. Siny; S. G. Lushnikov; S. I. Siny; V. H. Schmidt; A. A. Savvinov; R. S. Katiyar

2001-01-01

165

Relaxor-PT single crystals for broad bandwidth, high power sonar projectors  

Microsoft Academic Search

The high piezoelectric response of the ferroelectric relaxor (1 - x)Pb(Mg1\\/3Nb2\\/3)O3 - xPbTiO3 (PMNT) in single crystal form has generated significant interest in producing broad bandwidth SONAR systems. Both the piezoelectric coefficient (d33 > 2000 pC\\/N) and coupling coefficient (k33 > 0.90) are superior to those of conventional piezoelectric ceramics. Within the context of a high power acoustic projector, its

Nevin P. Sherlock

2010-01-01

166

Local structure in BaTi1-xZrxO3 relaxors from neutron pair distribution function analysis  

NASA Astrophysics Data System (ADS)

The pair distribution functions (PDF) of BaTi1-xZrxO3 (BTZ) relaxors (x=0.25,0.32,0.35) , as well as those of the end members BaTiO3 and BaZrO3 , were determined at 300 K from neutron powder scattering data. In the relaxors, the PDF provides direct evidence that the Ti and Zr atoms do not occupy the equivalent octahedral sites expected from the crystallographic cubic perovskite structure. It is shown that the TiO6 and ZrO6 octahedra in BTZ relaxors are instead similar to those observed in BaTiO3 and BaZrO3 , respectively. In BaZrO3 , the Zr atoms lie at the center of regular oxygen octahedra, forming nonpolar ZrO6 units. In the tetragonal ferroelectric phase of BaTiO3 , the distribution of Ti-O distances within TiO6 octahedra is found compatible with a displacement of the Ti atoms in the [111]p direction of the pseudocubic perovskite cell. We conclude that the local polarization in BTZ relaxors is mainly due to the displacements of the Ti atoms and that moreover the Ti displacements are very similar in BTZ relaxors and in the classical ferroelectric BaTiO3 .

Laulhé, C.; Hippert, F.; Bellissent, R.; Simon, A.; Cuello, G. J.

2009-02-01

167

Effect of disorder potential on domain switching behavior in polymer ferroelectric films.  

PubMed

Nanoscale switching dynamics in spin-coated ferroelectric copolymer films of polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE 75/25) has been investigated via high-resolution real-space imaging of electrically induced domain structure evolution using resonance-enhanced piezoresponse force microscopy. It has been shown that in strongly imprinted films application of switching pulses of opposite polarity results in qualitatively different domain switching dynamics. A distinct feature of domain dynamics is roughening of the domains walls during switching to the preferred polarization state as opposed to smooth domain boundaries during switching to the opposite direction. The observed switching behavior is explained by a combined effect of the spatially uniform built-in electric field and local disorder potential. Application of the external potential changes the balance between the two and creates conditions under which domain growth is dominated either by the average built-in electric field or local random-bond disorder potential. PMID:23221321

Sharma, Pankaj; Nakajima, Takashi; Okamura, Soichiro; Gruverman, Alexei

2013-01-11

168

Influence of cycling electric polarization on multiferroic behaviors in heterostructural films composed of ferroelectric and ferromagnetic oxides  

NASA Astrophysics Data System (ADS)

The CoFe2O4/Pb(Zr0.52Ti0.48)O3 bilayer films were prepared by a sol-gel process, and the influence of cycling electric polarization on the multiferroic behaviors of the bilayer films was studied. The ferroelectric polarization hysteresis loops under various choices of magnetic bias were measured by an integrating current method. The results showed that after undergoing cycling electric polarization the ferroelectric polarization of the bilayer films enhanced and the suppression of ferroelectric polarization by external magnetic bias remarkably weakened. Based on the measurements of activation energy and leakage current, we confirmed that the oxygen vacancy migration in the bilayer films occurred during cycling electric polarization. Furthermore, we analyzed the mechanism of the influence of cycling electric polarization on the multiferroic behaviors of the bilayer films and attributed it to the oxygen vacancy migration, which could cause a part of ferroelectric domains to be unpinned from the oxygen vacancies and become more active under electric field and magnetic bias.

Li, Zi-Wei; Zhou, Ming-Xiu; Chen, Bo; Wan, Jian-Guo; Liu, Jun-Ming; Wang, Guang-Hou

2013-11-01

169

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)

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+.

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

2014-03-01

170

Interfacial charge and strain effects on the ferroelectric behavior of epitaxial (001) PbTiO3 films on (110) DyScO3 substrates  

NASA Astrophysics Data System (ADS)

In-situ synchrotron x-ray observations reveal that the ferroelectric behavior of epitaxial (001) PbTiO3 thin films grown on (110) DyScO3 substrates depends on both film thickness and interfacial electrical properties. A 92-nm-thick film was found to exhibit an a/c domain structure with a ferroelectric Curie temperature similar to that theoretically predicted based on the strain state. In contrast, 6-nm-thick films contained only c-oriented domains, and the ferroelectric behavior was found to depend strongly on the nature of the electrical boundary condition at the buried interface.

Highland, M. J.; Fong, D. D.; Stephenson, G. B.; Fister, T. T.; Fuoss, P. H.; Streiffer, S. K.; Thompson, Carol; Richard, M.-I.; Eastman, J. A.

2014-03-01

171

Impact of compressive in-plane strain on the ferroelectric properties of epitaxial NaNbO3 films on (110) NdGaO3  

NASA Astrophysics Data System (ADS)

Epitaxial a-axis oriented NaNbO3 films are grown on (110) oriented NdGaO3 substrates. The lattice mismatch between substrate and film leads to compressive strain of ~0.7% in the a-c plane. As a consequence, the in-plane permittivity and tunability are strongly enhanced compared to bulk NaNbO3, and a pronounced maximum in the temperature dependence of the permittivity occurs. Below the maximum at Tmax ~ 250 K, ferroelectric behavior is observed that seems to vanish above Tmax. The pristine phase of the film at T < Tmax is antiferroelectric and is easily suppressed by small applied electric fields. The ferroelectric phase shows a relaxor type behavior.

Wördenweber, R.; Schwarzkopf, J.; Hollmann, E.; Duk, A.; Cai, B.; Schmidbauer, M.

2013-09-01

172

Investigaction of Switching Behavior in a Ferroelectric Liquid Crystal Aligned on Obliquely Deposited SiO Films  

Microsoft Academic Search

The effect of oblique evaporation of SiO on the chevron structure and the switching behavior in a ferroelectric liquid crystal have been investigated by means of the X-ray diffraction and the stroboscopic micrographs. It is found experimentally that the chevron direction and the domain structure appearing during the switching are determined by the direction of incidence of evaporated SiO. On

Yuichiro Yamada; Norio Yamamoto; Tetsuya Inoue; Hiroshi Orihara; Yoshihiro Ishibashi

1989-01-01

173

Relaxor-PT Single crystals: Observations and Developments  

PubMed Central

Relaxor-PT based ferroelectric single crystals Pb(Zn1/3Nb2/3)O3–PbTiO3 (PZNT) and Pb(Mg1/3Nb2/3)O3–PbTiO3 (PMNT) attracted lot of attentions in last decade due to their ultra high electromechanical coupling factors and piezoelectric coefficients. However, owing to a strongly curved morphotropic phase boundary (MPB), the usage temperature of these perovskite single crystals is limited by TRT - the rhombohedral to tetragonal phase transition temperature, which occurs at significantly lower temperatures than the Curie temperature TC. Furthermore, the low mechanical quality factors and coercive fields of these crystals, usually being on the order of ~70 and 2–3kV/cm, respectively, restrict their usage in high power applications. Thus, it is desirable to have high performance crystals with high temperature usage range and high power characteristics. In this survey, different binary and ternary crystal systems were explored, with respect to their temperature usage range, general trends of dielectric and piezoelectric properties of relaxor-PT crystal systems were discussed related to their TC/TRT. In addition, two approaches were proposed to improve mechanical Q values, including acceptor dopant strategy, analogous to “hard” polycrystalline ceramics, and anisotropic domain engineering configurations.

Zhang, Shujun; Shrout, Thomas R.

2011-01-01

174

Phase diagram of thin-film relaxor PbMg1\\/3Nb2\\/3O3  

Microsoft Academic Search

Epitaxial heterostructures of pure perovskite relaxor ferroelectric PbMg1\\/3Nb2\\/3O3 thin films were grown by pulsed laser ablation varying the temperature of deposition. Dielectric response of the films was studied as a function of frequency, temperature, amplitude of ac electric field, and magnitude of dc electric field. The temperatures of dielectric maxima and the freezing temperatures determined in different regimes were analyzed

M. Tyunina; J. Levoska

2005-01-01

175

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

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.

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

176

Soft mode dynamics and the reduction of Ti4+ disorder in ferroelectric/relaxor superlattices BaTiO3/BaTi0.68Zr0.32O3  

NASA Astrophysics Data System (ADS)

We used pulsed laser deposition to grow a series of [BaTiO3]?/2/[BaTi0.68Zr0.32O3]?/2 (BTZ/BT) superlattices (SL’s) with a modulation period ? that varies between 16Å???1008Å ; the total thickness is kept constant at about 4000Å . We determine the out-of-plane lattice parameters of the SL constituents by modeling the x-ray diffractograms of the SL’s. The results indicate that the polar c axis of the BT layers lies in the plane of the film. The Raman data reinforces this interpretation. The Raman spectra of SL’s give evidence of coupling between BT and BTZ layers and a narrowing of the Raman peaks suggest a reduction of the disorder of the Ti4+ ions due to the strain. This strain resulting from the lattice mismatch between the constituent layers is responsible for the upward frequency shift of the soft modes, especially the E(1TO) mode, which is markedly altered with respect to its analogs in BT-bulk crystals and BT film. This soft-mode behavior as a function of ? indicates that the crystal structure of all SL’s is more rigid than in BTZ and BT single thin films.

de Guerville, F.; El Marssi, M.; Raevski, I. P.; Karkut, M. G.; Yuzyuk, Yu. I.

2006-08-01

177

Broadband inelastic light scattering study on relaxor ferroelectric Pb(In1/2Nb1/2)-Pb(Mg1/3Nb2/3)O3-PbTiO3 single crystals  

NASA Astrophysics Data System (ADS)

The broadband inelastic light scattering spectra of ternary Pb(In1/2Nb1/2)-Pb(Mg1/3Nb2/3)O3-PbTiO3 single crystals were investigated as a function of temperature and crystal orientation by combining Raman and Brillouin spectroscopies. The angular dependence of the strong Raman peak located at ˜50 cm-1 was investigated at 300 °C. The intensity variation of this mode with rotation angle was compatible with the F2g mode of Fm3¯m symmetry, suggesting that this mode arises from the 1:1 chemical order at the B-site in this perovskite structure. The temperature evolution of the polar nanoregions was associated with the growth of two central peaks and the change in the intensity of some Raman peaks, which were known to be sensitive to the rhombohedral symmetry. Both relaxation processes exhibited partial slowing-down behaviors with a common critical temperature of ˜160 °C. Poling the crystal along the [001] direction induced abrupt changes in some of the Raman bands at the rhombohedral-tetragonal phase transition. On the other hand, the diffuse tetragonal-cubic phase transition was not affected by the poling process. This high-temperature phase transformation seems to be smeared out by the inherent disorder and strong random fields enhanced by the addition of Pb(In1/2Nb1/2) into Pb(Mg1/3Nb2/3)O3-PbTiO3.

Hyun Kim, Tae; Kojima, Seiji; Ko, Jae-Hyeon

2014-06-01

178

Anomalous dielectric behavior of KH2PO4 type crystals in the ferroelectric phase  

Microsoft Academic Search

Experimental studies on the dielectric constants of KH2PO4 type ferroelectrics below the Curie temperature Tc are reviewed with special emphasis to the anomalously large dielectric constant and its abrupt decrease in the low temperature region called domain freezing. The origin of the large dielectric constant below Tc is explained in connection with the elastic softening in the multidomain crystals. The

Eiji Nakamura

1992-01-01

179

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

Microsoft Academic Search

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

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

2004-01-01

180

Energy principle and nonlinear electric–mechanical behavior of ferroelectric ceramics  

Microsoft Academic Search

Summary  Many experimental observations have shown that a single domain in a ferroelectric material switches by progressive movement\\u000a of domain walls, driven by a combination of electric field and stress. The mechanism of the domain switch involves the following\\u000a steps: initially, the domain has a uniform spontaneous polarization; new domains with the reverse polarization direction nucleate,\\u000a mainly at the surface, and

F. Liu; H. J. Li; T. C. Wang

2008-01-01

181

Ferroelectric Pump  

NASA Technical Reports Server (NTRS)

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.

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

2000-01-01

182

Organic ferroelectrics  

Microsoft Academic Search

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

Sachio Horiuchi; Yoshinori Tokura

2008-01-01

183

Evidence of ferroelectricity in SrFeO3-?  

NASA Astrophysics Data System (ADS)

Perovskite SrFeO3-? belongs to the Ruddlesden-Popper class of system exhibiting interesting electronic and magnetic properties. Nanocrystalline SrFeO3-? synthesized successfully by the thermal decomposition method has the cubic phase as confirmed from x-ray diffraction. The non-stoichiometric nature is confirmed from the selected area electron diffraction pattern. Oxygen stoichiometry, which plays an important role in determining the physical properties, was found to be 2.91 from the iodometric titration. Mössbauer measurement reveals paramagnetic behaviour and suggests mixed valence state of Fe. Relaxor type ferroelectricity is evident from the dielectric plots, which is also reflected in the thermal study. Relaxor ferroelectric behaviour is reported for the first time in SrFeO2.91, arising due to mixed valency of Fe ion.

Manimuthu, P.; Venkateswaran, C.

2012-01-01

184

Pb(Mg 1\\/3 Nb 2\\/3 )O 3 and (1 ? x )Pb(Mg 1\\/3 Nb 2\\/3 )O 3 ? x PbTiO 3 Relaxor Ferroelectric Thick Films: Processing and Electrical Characterization  

Microsoft Academic Search

The lead magnesium niobate [Pb(Mg1\\/3Nb2\\/3)O3 or PMN], and its solid solutions with lead titanate (PbTiO3 or PT), are of great interest because of their high electromechanical properties. At large PMN content, these materials exhibit relaxor characteristics with large electrostrictive strains and a large permittivity, while compositions near the morphotropic phase boundary present very interesting piezoelectric properties. So far, properties of

S. Gentil; D. Damjanovic; N. Setter

2004-01-01

185

Electrocaloric Effect and Dipolar Entropy Change in Ferroelectric Polymers  

Microsoft Academic Search

The electrocaloric (EC) effect in normal ferroelectric copolymer P(VDF-TrFE) and in relaxor terpolymer P(VDF-TrFE-CFE) is described in the framework of a phenomenological appoach. The change of the dipolar entropy in the copolymer, derived earlier from dielectric measurements by means of the Maxwell relation, is analyzed in terms of the mean field expression for entropy, and is shown to be consistent

R. Pirc; B. Roži?; Z. Kutnjak; R. Blinc; Xinyu Li; Q. M. Zhang

2012-01-01

186

Growth and characterization of piezo-/ferroelectric Pb(Mg 1/3Nb 2/3)O 3-PbTiO 3-Bi(Zn 1/2Ti 1/2)O 3 ternary single crystals  

NASA Astrophysics Data System (ADS)

In order to develop new piezo-/ferroelectric materials, single crystals of the Pb(Mg 1/3Nb 2/3)O 3-PbTiO 3-Bi(Zn 1/2Ti 1/2)O 3 [PMN-PT-BZT] ternary complex perovskite system has been grown by a high temperature solution method using the mixture of PbO and H 3BO 3 as flux (in a molar ratio of 4:2) with an optimum flux:charge molar ratio of 6:1. It is found that the addition of BZT into the relaxor ferroelectric PMN-PT system reduces the number of spontaneous nucleations, resulting in large single crystals (5 mm×5 mm×14 mm) of good quality. The grown crystals exhibit a pseudo-cubic morphology and show evidence of two-dimensional growth mechanism. Examination by polarized light microscopy (PLM) reveals the formation of striation, which can be reduced by changing the growth conditions. The domain structure and phase transition of the PMN-PT-BZT crystals are investigated by PLM. The temperature and frequency dependences of the dielectric permittivity of the grown crystals show typical relaxor ferroelectric behavior, with the frequency dependence of the temperature of maximum permittivity ( Tmax) following the Vogel-Fulcher law. The ferroelectric property is displayed in the crystals with a remnant polarization, Pr=21 ?C/cm 2 and a coercive field, EC=3.5 kV/cm. The piezoelectric coefficient, d33, is found to be 825 pC/N, a value much higher than that of the ternary ceramics.

Belan, Reagan A.; Tailor, Hamel N.; Long, Xifa; Bokov, Alexei A.; Ye, Zuo-Guang

2011-03-01

187

Constitutive relations of ferroelectric ceramics  

Microsoft Academic Search

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

Yu Su

2003-01-01

188

Compositional engineering of BaTiO3/(Ba,Sr)TiO3 ferroelectric superlattices  

NASA Astrophysics Data System (ADS)

Epitaxial strain is one of the major factors influencing physical properties of artificial superlattice (SL) structures. One way to control the local stress in epitaxial films is altering the lattice parameters by doping. Superlattices of BT/Ba(1-x)SrxTiO3 (BT/BST) with x = (0, 0.3, 0.4, 0.5, 0.6, 0.7, 1) with a modulation period of about 80-90 A? were grown on La0.67Sr0.33MnO3 coated (100) MgO substrates by pulsed laser deposition technique. The modulated structure of the thin films was confirmed by x-ray diffraction, Raman spectroscopy, and transmission electron microscopy. The increase in Sr concentration in BST layers of the SLs results in an increase in in-plane (a) and out-plane (c) compressive/tensile misfit strains in the BT/BST layers, respectively. The highest value of the dielectric constant was obtained for BT/Ba0.3Sr0.7TiO3 (BT/BST3070) and BT/Ba0.7Sr0.3TiO3 (BT/BST7030) SLs. Slim, asymmetric, but well-saturated ferroelectric hysteresis loops were observed in all SLs. Additionally, BT/BST SLs exhibited exceptionally high electric field stress sustainability over a wide range of frequency (10 kHz) and temperature (80-350 K). Temperature-dependent dielectric and ferroelectric properties show a ferroelectric relaxor behavior when the Sr content is increased in the BST layer of the SLs. Analysis of polarization versus temperature data using Landau-Devonshire theory suggests a second-order ferroelectric phase transition in these SLs. This structure can therefore be attractive in the design of a new kind of dielectric device capable in both high power and high energy density applications.

Ortega, N.; Kumar, Ashok; Resto, Oscar; Maslova, O. A.; Yuzyuk, Yu. I.; Scott, J. F.; Katiyar, Ram S.

2013-09-01

189

Dielectric properties of high-pressure synthesized relaxor PbMg1\\/3Nb2\\/3O3 ceramics  

Microsoft Academic Search

Single-phase perovskite PbMg1\\/3Nb2\\/3O3(PMN) ceramics were synthesized from stoichiometric oxide mixtures under conditions of high pressures and temperatures. Results of dielectric studies of this material show that the high-pressure PMN ceramics consist of two phases. One of them exhibits the properties of a dipole-ordering phase with a diffuse transition and another is a relaxor–ferroelectric phase. When annealing, the high-pressure synthesized PMN

N M Olekhnovich; N P Vyshatko; Yu V Radyush; A N Salak; V M Ferreira

2003-01-01

190

Dielectric properties of high-pressure synthesized relaxor PbMg1\\/3Nb2\\/3O3 ceramics  

Microsoft Academic Search

Single-phase perovskite PbMg1\\/3Nb2\\/3O3 (PMN) ceramics were synthesized from stoichiometric oxide mixtures under conditions of high pressures and temperatures. Results of dielectric studies of this material show that the high-pressure PMN ceramics consist of two phases. One of them exhibits the properties of a dipole-ordering phase with a diffuse transition and another is a relaxor-ferroelectric phase. When annealing, the high-pressure synthesized

N. M. Olekhnovich; N. P. Vyshatko; Yu V. Radyush; A. N. Salak; V. M. Ferreira

2003-01-01

191

The effect of poling and depoling on the dielectric and piezoelectric properties of relaxor ferroelectric solid solution single crystal of 24Pb(In1\\/2Nb1\\/2)O3 -46Pb(Mg1\\/3Nb2\\/3)O3 -30PbTiO3  

Microsoft Academic Search

The dielectric property and domain structures of relaxor 24Pb(In 1I2Nb 112)03-46Pb(MgII3Nb2\\/3) 03-30PbTi03 were studied by dielectric spectroscopy, polarized light microscopy (PLM) and piezoresponse force microscopy (PFM). Remarkable differences between heating and cooling run in permittivity vs. T curve and domain structures for poled specimen were found. The change in domain structures with poling from rhombohedral spindle-like domains with a few

Y. Tachi; Y. Yamashita

2011-01-01

192

KTa\\/sub 0.6\\/Nb\\/sub 0.4\\/O\\/sub 3\\/ ferroelectric thin film behavior at microwave frequencies for tunable applications  

Microsoft Academic Search

In this study about the relationships between structural and microwave electrical properties of KTa1-xNbxO3 (KTN) ferroelectric materials, a KTN thin film was deposited on different substrates to investigate how KTN growth affects the microwave behavior. Interdigital capacitors and stubs were made on these films through a simple engraving process. Microwave measurements under a static electric field showed the importance of

Vincent Laur; Anthony Rousseau; Gerard Tanne; Paul Laurent; Stephanie Deputier; Maryline Guilloux-Viry; Fabrice Huret

2006-01-01

193

Behavior of inclusions with different value and orientation of topological dipoles in ferroelectric smectic films  

SciTech Connect

Cholesteric droplets in ferroelectric free-standing films with tunable anchoring on the droplet boundary are investigated. A droplet and satellite topological defect(s) form a topological dipole. We obtained droplets with different angles {alpha} between two radial lines from the droplet center to -1/2 topological defects. Droplets with parallel dipoles form linear chains in which the interparticle distances decrease with increasing the defect angle {alpha}. For the first time, the dependence of the interparticle distance on the angle between topological defects was measured. We can adjust the magnitude and orientation of topological dipoles formed by the droplets. For the first time, the droplets with antiparallel topological dipoles were prepared in a smectic film. Interaction of the droplets with parallel and antiparallel dipoles differs drastically. Formation of antiparallel dipoles leads to a decomposition of the droplet pairs and chains of droplets. Our observations may be used to change the magnitude, anisotropy of the interparticle interaction, and structures of inclusions in liquid crystal media.

Dolganov, P. V., E-mail: pauldol@issp.ac.ru; Dolganov, V. K. [Russian Academy of Sciences, Institute of Solid State Physics (Russian Federation); Cluzeau, P. [Universite Bordeaux I, Centre de Recherche Paul Pascal, CNRS (France)

2009-07-15

194

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

SciTech Connect

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.

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

195

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

NASA Astrophysics Data System (ADS)

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 ?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 deff of about 35% of its initial value for the thin films at a maximum force of 500 mN.

Koval, V.; Reece, M. J.; Bushby, A. J.

2005-04-01

196

Nonlinear-optic and ferroelectric behavior of lithium borate{endash}strontium bismuth tantalate glass{endash}ceramic composite  

SciTech Connect

Transparent glasses in the system (100{endash}x) Li{sub 2}B{sub 4}O{sub 7}{endash}xSrBi{sub 2}Ta{sub 2}O{sub 9} (0{le}x{le}20) were fabricated via a splat-quenching technique. The glassy nature of the as-quenched samples was established by differential thermal analyses. X-ray powder diffraction and transmission electron microscopic studies confirmed the amorphous nature of the as-quenched and crystallinity (40 nm) in the heat-treated (glass{endash}ceramic) samples. The dielectric constant ({epsilon}{sub r}) of the glass{endash}ceramic composite (x=20, heat treated at 773 K/8 h) was in between that of the parent host glass (Li{sub 2}B{sub 4}O{sub 7}) and strontium bismuth tantalate ceramics in the frequency range 100 Hz{endash}40 MHz at 300 K. These exhibited intense second-harmonic generation and a ferroelectric hysteritic behavior (P vs E loops) at 300 K. The coercive field (E{sub c}) and the remnant polarization (P{sub r}) were 1053 V/cm and 0.483 {mu}C/cm2, respectively. {copyright} 2001 American Institute of Physics.

Senthil Murugan, G.; Varma, K. B. R.; Takahashi, Yoshihiro; Komatsu, Takayuki

2001-06-18

197

Collective dipole behavior and unusual morphotropic phase boundary in ferroelectric Pb(Zr(0.5)Ti(0.5))O3 nanowires.  

PubMed

Dipole collective behavior and phase transition in ferroelectric (FE) Pb(Zr(0.5)Ti(0.5))O(3) nanowires, caused by modulated electric fields, are reported. Our result also leads to the finding of a rather outstanding electromechanical d(31) response in a 8.4 nm diameter PZT wire, which may potentially outperform bulk PMN-PT and PZN-PT. Moreover, we further demonstrate the existence of a new type of morphotropic phase boundary (MPB) that bridges two dissimilar structure phases of different order parameters. Microscopic insights for understanding the collective behavior and the structural phase within the new MPB are provided. PMID:23256599

Fu, Xiujun; Naumov, Ivan I; Fu, Huaxiang

2013-02-13

198

Geometric frustration in compositionally modulated ferroelectrics.  

PubMed

Geometric frustration is a broad phenomenon that results from an intrinsic incompatibility between some fundamental interactions and the underlying lattice geometry. Geometric frustration gives rise to new fundamental phenomena and is known to yield intriguing effects such as the formation of exotic states like spin ice, spin liquids and spin glasses. It has also led to interesting findings of fractional charge quantization and magnetic monopoles. Mechanisms related to geometric frustration have been proposed to understand the origins of relaxor and multiferroic behaviour, colossal magnetocapacitive coupling, and unusual and novel mechanisms of high-transition-temperature superconductivity. Although geometric frustration has been particularly well studied in magnetic systems in the past 20 years or so, its manifestation in the important class formed by ferroelectric materials (which are compounds with electric rather than magnetic dipoles) is basically unknown. Here we show, using a technique based on first principles, that compositionally graded ferroelectrics possess the characteristic 'fingerprints' associated with geometric frustration. These systems have a highly degenerate energy surface and display critical phenomena. They further reveal exotic orderings with novel stripe phases involving complex spatial organization. These stripes display spiral states, topological defects and curvature. Compositionally graded ferroelectrics can thus be considered the 'missing link' that brings ferroelectrics into the broad category of materials able to exhibit geometric frustration. Our ab initio calculations allow deep microscopic insight into this novel geometrically frustrated system. PMID:21307851

Choudhury, Narayani; Walizer, Laura; Lisenkov, Sergey; Bellaiche, L

2011-02-24

199

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

NASA Astrophysics Data System (ADS)

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.

Harker, John Chamberlain

200

Ferroelectric memories  

Microsoft Academic Search

In the past year it has become possible to fabricate ferroelectric thin-film memories onto standard silicon integrated circuits that combine very high speed (30-nanosecond read\\/erase\\/rewrite operation), 5-volt standard silicon logic levels, very high density (2 by 2 micrometer cell size), complete nonvolatility (no standby power required), and extreme radiation hardness. These ferroelectric random-access memories are expected to replace magnetic core

J. F. Scott; C. A. Paz de Araujo

1989-01-01

201

Absence of the heat capacity anomaly in the Pb-free relaxor BaTi0.65Zr0.35O3  

NASA Astrophysics Data System (ADS)

A relaxor ferroelectrics, BaTi0.65Zr0.35O3 (BTZ35), which was free from lead, was synthesized and the physicothermal properties were measured. The heat capacity was measured using a homemade adiabatic calorimeter at temperatures from 13Kto420K , and the dielectric constant measurements were carried out between 1kHz and 1MHz at temperatures from 20Kto420K . No anomaly was detected in the heat capacity curve for the whole temperature range covered in the present experiments, while a large and broad peak was observed in the dielectric constant curve. The dielectric constant showed the relaxor type frequency dependence. The results of the present experiments were compared with our previous studies on a typical relaxor of lead-based complex perovskite oxide, PbMg1/3Nb2/3O3 (PMN), which showed a large heat capacity anomaly as well as a large broad peak of dielectric constant due to formation of ferroelectric polar nanoregion in the crystal. Some differences between the two compounds, BTZ35 and PMN, were compared and the mechanism was discussed.

Nagasawa, Motoi; Kawaji, Hitoshi; Tojo, Takeo; Atake, Tooru

2006-10-01

202

Relaxor in KF-doped BaTi2O5 ceramics by spark plasma sintering  

NASA Astrophysics Data System (ADS)

Dense BaTi2O5 ceramics with KF doping up to 5 at. % were synthesized by spark plasma sintering (SPS). The SPS method enabled us to overcome the densifying difficulty in conventional sintering which is caused by the limit of the decomposing temperature of this metastable phase. We observed drastic KF-doping effect on the ferroelectric (FE) properties of BaTi2O5. Although there is only very small change in lattice parameters upon KF doping, the peak temperature in dielectric constant strongly decreases in an exponential way. The diffuseness of phase transition increases and FE relaxor state sets in for KF content as low as 1 at. %. Possible structural reasons for the effect and the implication for the nature of FE phase transition in BaTi2O5 are discussed.

Xu, Jun; Akishige, Yukikuni

2008-02-01

203

Lead Perovskite Relaxor-Based Low-Loss Ceramic Dielectric for High-Voltage Ceramic Capacitors  

NASA Astrophysics Data System (ADS)

A low-loss ceramic dielectric with a less than 0.1% dissipation factor at 100 kHz, based on a modified lead zinc niobate relaxor, has been fabricated by shifting the ferroelectric transition temperature (Tc) to below -55°C. This dielectric has a high dielectric constant (K), ranging from 250 to 2000. The temperature coefficient of capacitance (TCC) locates at the middle area between values for temperature compensation dielectric and values for high-K dielectric. Even at 150°C, high insulation resistance, more than 5× 1013 ?cm, was also retained. Moreover, a typical composition with K{=}530 revealed that the dielectric has a high breakdown voltage of 95 kV per 10 mm of thickness and a TCC value of -2900 ppm/°C. Accordingly, this dielectric has proven useful for high-voltage ceramic capacitors.

Furukawa, Osamu; Yamashita, Yohachi; Harata, Mitsuo

1991-09-01

204

Aging behavior in single-domain Mn-doped BaTiO3 crystals: Implication for a unified microscopic explanation of ferroelectric aging  

Microsoft Academic Search

The change of ferroelectric, dielectric, and piezoelectric properties with time, the ferroelectric aging phenomena, has been observed in most ferroelectrics. Phenomenologically, aging can be attributed to the gradual stabilization of ferroelectric domains by defects, but the microscopic origin of the domain stabilization has remained controversial. It is unclear whether the domain stabilization is a boundary effect (caused by domain-wall-pinning) or

Lixue Zhang; Xiaobing Ren

2006-01-01

205

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

PubMed

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

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

2011-12-01

206

Relaxor behavior in nanostructured Pb(Zn1/3Nb2/3)O3-Pb(Fe1/2Nb1/2)O3-PbTiO3 ceramics  

NASA Astrophysics Data System (ADS)

There is controversy about the persistence or not of the relaxor state in the nanoscale. We report here the dielectric properties of nanostructured ceramics of the Pb(Zn1/3Nb2/3)O3-Pb(Fe1/2Nb1/2)O3-PbTiO3 ternary system with an average grain size of 20 nm, which clearly indicate that it persists as long as correlations among polar nanoregions are possible across grain boundaries. Two independent Vogel-Fulcher type relaxations are found in the materials that have a non-negligible width of the size distribution, which are proposed to be associated with intra- and intergranular correlations that show freezing at different temperatures.

Amorín, H.; Jiménez, R.; Hungría, T.; Castro, A.; Algueró, M.

2009-04-01

207

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

NASA Astrophysics Data System (ADS)

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.

Liu, Cheng; Liu, Peng

2010-12-01

208

Reassessment of the Burns temperature and its relationship to the diffuse scattering, lattice dynamics, and thermal expansion in relaxor Pb(Mg1\\/3Nb2\\/3)O3  

Microsoft Academic Search

We have used neutron scattering techniques that probe time scales from 10-12 to 10-9s to characterize the diffuse scattering and low-energy lattice dynamics in single crystals of the relaxor PbMg1\\/3Nb2\\/3O3 (PMN) from 10 to 900 K. Our study extends far below Tc=213K , where long-range ferroelectric correlations have been reported under field-cooled conditions, and well above the nominal Burns temperature

P. M. Gehring; H. Hiraka; C. Stock; S.-H. Lee; W. Chen; Z.-G. Ye; S. B. Vakhrushev; Z. Chowdhuri

2009-01-01

209

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)

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.

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

2013-07-01

210

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  

PubMed Central

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.

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

2013-01-01

211

Hyperferroelectrics: Proper Ferroelectrics with Persistent Polarization  

NASA Astrophysics Data System (ADS)

All known proper ferroelectrics are unable to polarize normal to a surface or interface if the resulting depolarization field is unscreened, but there is no fundamental principle that enforces this behavior. In this work, we introduce hyperferroelectrics, a new class of proper ferroelectrics which polarize even when the depolarization field is unscreened, this condition being equivalent to instability of a longitudinal optic mode in addition to the transverse-optic-mode instability characteristic of proper ferroelectrics. We use first-principles calculations to show that several recently discovered hexagonal ferroelectric semiconductors have this property, and we examine its consequences both in the bulk and in a superlattice geometry.

Garrity, Kevin F.; Rabe, Karin M.; Vanderbilt, David

2014-03-01

212

Ferroelectric Memories.  

National Technical Information Service (NTIS)

In the past year it has become possible to fabricate ferroelectric thin-film memories onto standard silicon integrated circuits that combine very high speed (30-nanosecond read/erase/rewrite operation), 5-volt standard silicon logic levels, very high dens...

J. F. Scott C. A. Paz De Arujo

1989-01-01

213

All-atom effective models for first-principles simulations of the temperature-dependent behavior of complex ferroelectric oxides  

Microsoft Academic Search

Since its introduction in the 90's, the first-principles effective-Hamiltonian method has been successfully used to simulate temperature-driven phenomena in increasingly complex ferroelectrics, from classic compound BaTiO3 to multiferroic BiFeO3. Currently, the emergence of nano-structured materials -- e.g., in the form of ultra-thin films or short-period superlattices -- poses new challenges to the simulations, and the development of predictive models seems

Jorge Iniguez; Jacek C. Wojdel; Patrick Hermet; Philippe Ghosez; Zeila Zanolli

2011-01-01

214

Coexistence of Antiferromagnetic and Spin Cluster Glass Order in the Magnetoelectric Relaxor Multiferroic PbFe0.5Nb0.5O3  

NASA Astrophysics Data System (ADS)

The coexistence of cluster glass with long-range antiferromagnetic order in the relaxor ferroelectric PbFe0.5Nb0.5O3 is elucidated. While the transition at TN=153K on the infinite antiferromagnetic cluster induces 3m symmetry with large EH2 magnetoelectric response, the disconnected subspace of isolated Fe3+ ions and finite clusters accommodates the cluster glass below Tg=10.6K with field-induced m' symmetry and EH-type magnetoelectric response. Critical slowing-down, memory and rejuvenation after aging, occurrence of a de Almeida-Thouless phase line, and stretched exponential relaxation of remanence corroborate the glass nature.

Kleemann, W.; Shvartsman, V. V.; Borisov, P.; Kania, A.

2010-12-01

215

Size effects in a relaxor: further insights into PMN.  

PubMed

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

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

2014-07-01

216

Microstructure and dielectric relaxor properties for Ba0.5Sr0.5TiO3/La0.67Sr0.33MnO3 heterostructure  

NASA Astrophysics Data System (ADS)

Ferroelectric and magnetoresistance heterostructure (Ba,Sr)TiO3/(La,Sr)MnO3 (BST/LSMO) heterostructure is deposited epitaxially on SrTiO3 (001) substrate by pulse laser deposition. The phase structures of the BST/LSMO heterostructure are characterized by x-ray diffraction. Cross-sectional transmission electron microscope shows a substantial interdiffusision between BST and LSMO layers. The dielectric properties and conductivity of BST/LSMO heterostructure is measured as a function of temperature, frequency, and electric field. The dielectric constant dependence on electric field, ? vs E, exhibits a strong nonlinear behavior in the temperature from 20 to 300 K, while V(E=0) vs T relation shows a dielectric relaxor characteristic. Furthermore, the dielectric constant (E=0 kV/cm) and the dielectric tunability (E=200 kV/cm) are found to be similar temperature dependencies. Last, in the temperature regime where a semiconduction-type conduction became dominate, the activation thermal energy of BST/LSMO heterostructure is estimated to be 0.67 and 0.73 eV at 1 kHz and 1 MHz, respectively.

Miao, J.; Tian, H. Y.; Zhou, X. Y.; Pang, K. H.; Wang, Y.

2007-04-01

217

Ion Implantation in Perovskite Type Ferroelectrics.  

National Technical Information Service (NTIS)

The object of this work was to study ion implantation in perovskite ferroelectrics and to investigate the conductive behavior of implanted layers. Implantation experiments were carried out on strontium titanate, barium titanate (single crystal and ceramic...

R. Gerson

1979-01-01

218

Ferroelectric aging behaviors of BaTi0.995Mn0.005O3 ceramics: grain size effects  

NASA Astrophysics Data System (ADS)

We report the ferroelectric aging effect of dense BaTi0.995Mn0.005O3 ceramics with grain size varying from 2000 nm to 150 nm. Given the identical aging process, it is revealed that the significant aging effect with clear double-hysteresis loop, observed in coarse-grain sample, is substantially suppressed with decreasing grain size. This suppression can be attributed to the reduction of tetragonal distortion and the grain boundary barrier effect in fine-grain sample. Consequently, the weak thermodynamic driving force and the limited kinetic migration are unfavorable to a reversible domain switching, resulting in a normal hysteresis loop in small grained samples.

Guo, Y. Y.; Yan, Z. B.; Zhang, N.; Cheng, W. W.; Liu, J.-M.

2012-04-01

219

Dynamics of nano-cluster in a new relaxor system: (PbMg 1/3Nb 2/3O 3)/(BiFeO 3)  

NASA Astrophysics Data System (ADS)

We report the dynamical role of nano-clusters in controlling the physical properties and parameters of a new relaxor complex, (PbMg 1/3Nb 2/3)O 3/(BiFeO 3). This complex shows a gradual structural change from cubic to hexagonal crystal system with increasing BiFeO 3 content. Transmission electron microscopy (TEM) reveals the presence of scattered nano-clusters for (PbMg 1/3Nb 2/3)O 3 relaxor system which starts assembling for increasing value of BiFeO 3. As a consequence of this assembling, a crossover from relaxor to ferroelectric and dielectric peak broadening was observed. Corresponding change in physical parameters such as; Curie-Weiss and Uchino-Nomura parameters i.e., ? Tcm and diffusivity ' ?' was also observed. Vogel-Fulcher (V-F) fitting was employed to calculate the activation energy required to activate the dipolar glasses into a dynamical state or to re-establish a polarization fluctuation around an isolated nano-cluster. V-F fitting shows increased activation energy for increasing cluster size. The suppression in polarization value shows the inability of the total dipole moment to reorient on application of electric field with growth/assembling of nano-clusters.

Sahoo, M. P. K.; Choudhary, R. N. P.

2010-07-01

220

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

NASA Astrophysics Data System (ADS)

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.

Tirupathi, Patri; Chandra, Amreesh

2013-09-01

221

Dynamics of Ferroelectric Domain Walls  

Microsoft Academic Search

Dielectric data obtained in the ferroelectric phase of KH2PO4 and Rb2ZnCl4 single crystals as well as in PZT-ceramics are provided demonstrating qualitatively similar behavior in quite different ferroelectric\\u000a systems. The peculiar low frequency dispersion, nonlinearity, dielectric loss and ageing phenomena, respectively, reflect\\u000a the creep-like dynamics of highly susceptible domain walls. The significance of the domain wall-defect interaction becomes\\u000a evident from

Volkmar Mueller

2001-01-01

222

Dynamics of Ferroelectric Domain Walls  

NASA Astrophysics Data System (ADS)

Dielectric data obtained in the ferroelectric phase of KH2PO4 and Rb2ZnCl4 single crystals as well as in PZT-ceramics are provided demonstrating qualitatively similar behavior in quite different ferroelectric systems. The peculiar low frequency dispersion, nonlinearity, dielectric loss and ageing phenomena, respectively, reflect the creep-like dynamics of highly susceptible domain walls. The significance of the domain wall-defect interaction becomes evident from the crucial influence of impurity type and concentration, respectively. The experimental results are discussed in terms of theoretical concepts developed for elastic interfaces in quenched disorder. The physical nature of the pinned elastic domain walls requires new approaches to characterize the properties of ferroelectric materials.

Mueller, Volkmar

223

Relaxor in KF-doped BaTi{sub 2}O{sub 5} ceramics by spark plasma sintering  

SciTech Connect

Dense BaTi{sub 2}O{sub 5} ceramics with KF doping up to 5 at. % were synthesized by spark plasma sintering (SPS). The SPS method enabled us to overcome the densifying difficulty in conventional sintering which is caused by the limit of the decomposing temperature of this metastable phase. We observed drastic KF-doping effect on the ferroelectric (FE) properties of BaTi{sub 2}O{sub 5}. Although there is only very small change in lattice parameters upon KF doping, the peak temperature in dielectric constant strongly decreases in an exponential way. The diffuseness of phase transition increases and FE relaxor state sets in for KF content as low as 1 at. %. Possible structural reasons for the effect and the implication for the nature of FE phase transition in BaTi{sub 2}O{sub 5} are discussed.

Xu Jun [Research Project Promotion Institute, Shimane University, Matsue, Shimane 690-8504 (Japan); Akishige, Yukikuni [Faculty of Education, Shimane University, Matsue, Shimane 690-8504 (Japan)

2008-02-04

224

Crystallization and Microstructural Control of Ferroelectric Thin-Films and Glass-Ceramics.  

National Technical Information Service (NTIS)

Research on solution-derived ferroelectric thin-films and melt-derived ferroelectric glass-ceramics was conducted in parallel with considerable overlap in the compositions studied and the evaluations of the crystallization behavior, microstructural develo...

M. J. Haun

1998-01-01

225

Crystallization and Microstructural Control of Ferroelectric Thin-Films and Glass-Ceramics.  

National Technical Information Service (NTIS)

Research on solution-derived ferroelectric thin-films and melt-derived ferroelectric glass-ceramics is being conducted in parallel with considerable overlap in the compositions studied and the evaluations of the crystallization behavior, microstructural d...

M. J. Haun

1993-01-01

226

Ferroelastic Behavior in Relaxor 24Pb(In1/2Nb1/2)O3--46Pb(Mg1/3Nb2/3)O3--30PbTiO3 under Shear Stresses along [001] Direction  

NASA Astrophysics Data System (ADS)

The ferroelastic behavior of relaxor 24Pb(In1/2Nb1/2)O3--46Pb(Mg1/3Nb2/3)O3--30PbTiO3 (PIN--PMN--PT) solid-solution single crystals was investigated under shear stresses using polarization light microscopy (PLM) and the scanning electron microscopy (SEM). Optical strain patterns along the \\{110\\}cub directions from the orthoscope images under crossed Nicol, induced by shear stresses applied along the [001]cub direction, making use of a Vickers microindenter with a square-base diagonal line oriented along the \\{100\\}cub directions of the crystal were observed on its (001)cub plate for the first time. These patterns at a diagonal position reveal a flowerlike pattern for ferroelastic transition from a square (S) lattice to a rectangular (R) lattice in a two-dimensional model system. A change in the interference color from yellow to blue through red toward the center in their flower leaves, according to the Michel--Levy birefringence chart, was observed. The patterns at the extinction position reveal starlike patterns coupled with lobes also due to orthorhombic and/or tetragonal twin domain structures. A blue shift (corresponding to addition in retardation) and a yellow shift (corresponding to subtraction in retardation) in color at each flower leaf in the [110]cub and [1\\bar{1}0]cub directions were respectively observed using a sensitive color plate. Such shifts in color correspond to oxygen octahedra being rotated in a staggered sense about the perovskite axis. The patterns appearing strongly along the \\{110\\}cub directions in spite of slip lines along the [100]cub, [010]cub, and [110]cub directions indicate the existence of a rotational preferred orientation in twin domain structures based on a pretransitional tweed domain structure due to platelets observed by SEM, leading to their superior piezoelectric properties due to large shear modes.

Yasuda, Naohiko; Hidayah, Nur; Ohwa, Hidehiro; Tachi, Yoshihito; Yamashita, Yohachi; Hlinka, Ing. Jiri; Iwata, Makoto; Terauchi, Hikaru; Ishibashi, Yoshihiro

2013-05-01

227

180 deg. domain structure and its evolution in Ca{sub 0.28}Ba{sub 0.72}Nb{sub 2}O{sub 6} ferroelectric single crystals of tungsten bronzes structure  

SciTech Connect

Ferroelectric domain structure and its evolution in uniaxial relaxor Ca{sub 0.28}Ba{sub 0.72}Nb{sub 2}O{sub 6} single crystals were investigated using transmission electron microscopy. It was found that there exists a high density of 180 deg. domain walls in the crystals. The domains appear predominantly spike shaped along the polar axis and have a typical diameter of 50-500 nm. Domain wall motion was occasionally induced by electron beam irradiation. Macrodomains-to-microdomains switching has been observed corresponding to the normal-to-relaxor ferroelectrics transition during an in situ heating experiments. At temperature just below ferroelectric phase transition temperature T{sub C}, zero-field-cooled needlelike nanodomains were also observed.

Lu, C.J.; Nie, C.J.; Duan, X.F.; Li, J.Q.; Zhang, H.J.; Wang, J.Y. [Department of Materials Science and Engineering, Hubei University, Wuhan, Hubei 430062, (China) and Institute of Physics, Chinese Academy of Sciences, Beijing 100080 (China); Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080 (China); Institute of Crystal Materials, Sandong University, Jinan 250100 (China)

2006-05-15

228

Field-induced strain behavior for potassium sodium bismuth titanate ceramics.  

PubMed

Data are reported for the dielectric, piezoelectric, electrostrictive, and ferroelectric properties of potassium-substituted sodium bismuth titanate, [(K(x)Na(1-x))(0.5)Bi(0.5)]TiO3. For the morphotropic phase boundary composition x = 0.2, relaxor-type behavior was observed at room temperature with piezoelectric (effective d(333) = 325 x 10(-12) m/V) and ferroelectric properties (P(R) = 25 microC/cm(2), E(C) = 30 kV/cm). A transition to a relatively frequency-independent, diffuse phase transformation region occurred with increasing temperature, with no remanent strain or coercive field. Above the transition temperature, the field-induced strain was consistent with contributions from electrostriction and field induced piezoelectricity (M(3333) = 1.9 x 10(-16) m2/V2 and d333 = 81 x 10(-12) m/V at 100 degrees C). Information is given for the temperature dependence of properties, e.g., 0.14% strain induced at 50 kV/cm at 200 degrees C. Higher potassium content x = 0.6 stabilized the ferroelectric piezoelectric region to temperatures above 200 degrees C, with a relatively stable d(333) = 150-145 x 10-12 m/V between 25 degrees C and 200 degrees C. Pb-free KNBT ceramics appear competitive with PZT, especially for higher temperature electromechanical applications. PMID:18276548

Carroll, James F; Payne, David A; Noguchi, Yuji; Miyayama, Masaru

2007-12-01

229

Structure, piezoelectric, and ferroelectric properties of BaZrO3 substituted Bi(Mg1/2Ti1/2)O3-PbTiO3 perovskite  

NASA Astrophysics Data System (ADS)

The structure and electric properties of (0.9-x)Bi(Mg1/2Ti1/2)O3-xPbTiO3-0.1BaZrO3 (0.45 <= x <= 0.53) ceramics were investigated. The morphotropic phase boundary between tetragonal ferroelectric and pseudo-cubic relaxor phases is ascertained at x = 0.50. The BaZrO3 substitution can much reduce the coercive field of Bi(Mg1/2Ti1/2)O3-PbTiO3. The studies on temperature dependence of both ferroelectric and dielectric constant indicate a direct evidence for the antiferroelectric relaxor phase, which was ever suggested in the binary system of Bi(Mg1/2Ti1/2)O3-PbTiO3. The phase transition of ferroelectric to antiferroelectric relaxor produces the thermal depoling below the Curie temperature. The ceramic of BMT-0.47PT-0.1BZ exhibits a high strain 0.37% and a large-signal d33 (530 pm/V) in the antiferroelectric-relaxor phase. BaZrO3 substituted Bi(Mg1/2Ti1/2)O3-PbTiO3 shows an analogous phase diagram to that of lead-free (Bi, Na)TiO3-BaTiO3.

Fan, Longlong; Chen, Jun; Kang, Huajun; Liu, Laijun; Fang, Liang; Deng, Jinxia; Yu, Ranbo; Xing, Xianran

2012-05-01

230

Ferroelectric ultrathin perovskite films  

DOEpatents

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.

Rappe, Andrew M; Kolpak, Alexie Michelle

2013-12-10

231

Anomalous Ferroelectric Hysteresis Loops.  

National Technical Information Service (NTIS)

Materials that exhibit anomalous ferroelectric hysteresis loops appear throughout the literature. These loops have irregular shapes that diverge from the normal hysteresis loop which is characteristic of most ferroelectrics. The observation of a unique hy...

F. J. Murdoch

1971-01-01

232

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

SciTech Connect

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.

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

233

Ferroelectric Materials: Ferroelectric Kinetics Computer Lab  

NSDL National Science Digital Library

The discussion on phase field modeling and conserved order-disorder transformations is extended to phase transformations for non-conserved order parameters. As an enabling application, a one-parameter two-dimensional ferroelectric material is described. The Allen-Cahn equation is presented. This lab is intended to complement the "Ferroelectric Materials: An Introduction" lecture.

Garcã­a, R. E.

2008-08-25

234

Fatigue and ferroelectric behavior of La and Zn comodified BiFeO{sub 3} thin films  

SciTech Connect

Bi{sub 0.90}La{sub 0.10}Fe{sub 0.95}Zn{sub 0.05}O{sub 3} (BLFZO) thin films were grown directly on Pt/TiO{sub 2}/SiO{sub 2}/Si(100) substrates without any buffer layer by off-axis radio frequency sputtering. The BLFZO thin film deposited at 580 deg. C possesses a single-phase purity, while those deposited at other temperatures exhibit a varying amount of second phases, indicating that the deposition temperature plays a critical role in the phase development of BLFZO thin films. Although La and Zn cosubstitutions lower the Curie temperature (T{sub c}) of BiFeO{sub 3} thin films, the resulting T{sub c} value ({approx}630 deg. C) is still much higher as compared to other lead-based or lead-free ferroelectric thin films. The BLFZO thin film exhibits a remanent polarization of 2P{sub r{approx}}131.7 {mu}C/cm{sup 2} and a coercive field of 2E{sub c{approx}}496 kV/cm, in association with the improvement in electrical resistance. On the basis of the studies for frequency (1 kHz{approx}1 MHz) and driving field (0.8E{sub c{approx}}2.0E{sub c}) dependences, the BLFZO thin film demonstrates the desired fatigue endurance and weak frequency and driving field dependence. La and Zn cosubstitutions are shown to contribute toward the high remanent polarization and fatigue endurance.

Wu Jiagang; Wang, John [Department of Materials Science and Engineering, Faculty of Engineering, National University of Singapore, Singapore 117574 (Singapore)

2010-07-15

235

A micro-electro-mechanical model for polarization switching of ferroelectric materials  

Microsoft Academic Search

Ferroelectric and ferroelastic switching are the major source of nonlinearity and hysteresis in ferroelectric materials subjected to high electric field or mechanical stress. A computational micromechanics model for polycrystalline ferroelectric ceramics is developed based on consideration of the constitutive behavior of single crystals. This model simulates the tetragonal and the rhombohedral crystal structures. Saturation of the linear piezoelectric effect is

W. Chen; C. S. Lynch

1998-01-01

236

Thermodynamic modeling of ferroelectric epitaxial films and polarization graded ferroelectrics  

NASA Astrophysics Data System (ADS)

Thermodynamic modeling based on the Landau-Ginzburg-Devonshire theory has been performed for epitaxial ferroelectric thin films and polarization graded ferroelectrics. The aim of this thesis is to provide a fundamental and systemic understanding of the role of internal stresses in the physical properties of epitaxial ferroelectric thin films as well as an explanation for the unconventional behavior of polarization graded ferroelectrics, thereby establishing a framework for materials/device design to enhance their properties. The thermodynamic analysis of single domain epitaxial barium strontium titanate (BST) thin films leads to the construction of misfit strain/electric field phase diagrams. The dielectric response, tunability and pyroelectric properties of the films are calculated as a function of the misfit strain. Analysis shows that high dielectric response, tunability, and pyroelectric coefficient can be achieved by adjusting the misfit strain especially in the vicinity of a structural phase transformation. Theoretical approach not only predicts general trends, but is also in good quantitative agreement with the experimental data reported in the literature. The stress relaxation by the formation of misfit dislocations is taken into account. It is suggested that the selection of the substrate and the film thickness can be chosen as design parameters to manipulate the internal stress level in the film to achieve enhanced electrical properties. A generalized Landau-Ginzburg-Devonshire model is constructed and used to develop a methodology for analyzing polarization graded ferroelectrics. A systematic variation in the polarization arises from composition, temperature, or stress gradients. These spatial non-uniformities are shown to give rise to local order parameters having corresponding spatial variation. Polarization graded ferroelectrics exhibit a displacement of the hysteresis curve along the polarization axis with "up" or "down" charge offsets due to the polarization gradient. A quantitative agreement between the theoretical calculations and the experimental data reported in the literature is found. Theoretical analysis of the dielectric and pyroelectric properties of polarization graded ferroelectrics shows that the polarization gradient can be used to adjust these properties and thereby provides a means to achieve enhanced properties. Extension of the thermodynamic approach to graded ferromagnets, ferroelastics, and other ferroic systems is also studied in this thesis.

Ban, Zhigang

237

Polar nanodomains and relaxor behaviour in (1 ? x)Pb(Mg 1\\/3Nb 2\\/3)O 3– xPbTiO 3 crystals with x = 0.3–0.5  

Microsoft Academic Search

Phase transitions and dielectric properties of the (1?x)Pb(Mg1\\/3Nb2\\/3)O3–xPbTiO3 crystals with x=0.3–0.5 are studied. The solid solutions in this composition range are shown to be relaxor ferroelectrics. The crystals with low x demonstrate a diffused maximum in the temperature dependences of the dielectric permittivity at Tm. Tm varies with frequency according to the Vogel–Fulcher law. The polarizing microscopy investigations reveal a

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

2005-01-01

238

Multiaxial models and experiments with ferroelectrics  

Microsoft Academic Search

The use of ferroelectrics in increasingly demanding roles as sensors and actuators motivates study of their fundamental constitutive behavior. This paper gives a preliminary report on measurements of the behavior of PZT-5H under multiaxial loading paths, and comparison with model predictions. The loading paths considered are loading of poled material with electric field at various angles (theta) to the poling

John E. Huber; Norman A. Fleck

2000-01-01

239

Pulse-loaded ferroelectric nanowire as an alternating current source.  

PubMed

The behavior of an uniaxially pulse-loaded ferroelectric nanowire is simulated using a Landau-Ginzburg type thermodynamic model. Our results show that under a load of suitable magnitude and frequency, an appropriately dimensioned ferroelectric nanowire can produce a sizable alternating current voltage, sufficient for applications as a nanopower source for energy harvesting, or as an effective nanomechanical sensor. PMID:18781805

Zheng, Yue; Woo, C H; Wang, B

2008-10-01

240

Ferroelectric mobile water.  

PubMed

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

Nakamura, Yoshimichi; Ohno, Takahisa

2011-01-21

241

Perovskite ferroelectric nanomaterials  

NASA Astrophysics Data System (ADS)

In this review, the main concept of ferroelectricity of perovskite oxides and related materials at nanometer scale and existing difficulties in the synthesis of those nanocrystals are discussed. Important effects, such as depolarization field and size effect, on the existence of ferroelectricity in perovskite nanocrystals are deliberated. In the discussion of modeling works, different theoretical calculations are pinpointed focusing on their studies of lattice dynamics, phase transitions, new origin of ferroelectricity in nanostructures, etc. As the major part of this review, recent research progress in the facile synthesis, characterization and various applications of perovskite ferroelectric nanomaterials, such as BaTiO3, PbTiO3, PbZrO3, and BiFeO3, are also scrutinized. Perspectives concerning the future direction of ferroelectric nanomaterials research and its potential applications in renewable energy, etc., are presented. This review provides an overview in this area and guidance for further studies in perovskite ferroelectric nanomaterials and their applications.In this review, the main concept of ferroelectricity of perovskite oxides and related materials at nanometer scale and existing difficulties in the synthesis of those nanocrystals are discussed. Important effects, such as depolarization field and size effect, on the existence of ferroelectricity in perovskite nanocrystals are deliberated. In the discussion of modeling works, different theoretical calculations are pinpointed focusing on their studies of lattice dynamics, phase transitions, new origin of ferroelectricity in nanostructures, etc. As the major part of this review, recent research progress in the facile synthesis, characterization and various applications of perovskite ferroelectric nanomaterials, such as BaTiO3, PbTiO3, PbZrO3, and BiFeO3, are also scrutinized. Perspectives concerning the future direction of ferroelectric nanomaterials research and its potential applications in renewable energy, etc., are presented. This review provides an overview in this area and guidance for further studies in perovskite ferroelectric nanomaterials and their applications. The authors declare no competing financial interests.

Nuraje, Nurxat; Su, Kai

2013-09-01

242

Diodelike and resistive hysteresis behavior of heterolayered BiFeO3\\/ZnO ferroelectric thin films  

Microsoft Academic Search

BiFeO3\\/ZnO, ZnO\\/BiFeO3, BiFeO3\\/ZnO\\/BiFeO3, and ZnO\\/BiFeO3\\/ZnO thin film heterostructures were deposited on SrRuO3\\/Pt(111)\\/TiO2\\/SiO2\\/Si(100) substrates by off-axis radio frequency sputtering. Their diodelike and resistive hysteresis behavior are dependent on the combination sequence of the constituent layers in the heterostructures. Both the diodelike and resistive hysteresis behavior were clearly observed in BiFeO3\\/ZnO and ZnO\\/BiFeO3. The phenomena became more apparent with rising temperature. The

Jiagang Wu; John Wang

2010-01-01

243

Kinetics of ferroelectric switching in ultrathin films  

NASA Astrophysics Data System (ADS)

The kinetics of polarization switching in ultrathin ferroelectric polymer films exhibit a critical behavior; there is a pronounced slowing just above the coercive field and just below the critical temperature. The critical slowing is observed in the switching kinetics of ferroelectric Langmuir-Blodgett films of 70% vinylidene-fluoride and 30% trifluoroethylene copolymer with thickness up to 30 ML. Thicker films exhibit an exponential dependence on the field and temperature that is normally associated with extrinsic switching by domain nucleation and growth. We show that the critical behavior arises naturally from the dynamics of homogeneous intrinsic switching in the context of mean-field theory. These results have important implications for the modeling and control of the ferroelectric films in nonvolatile computer memories and solid-state data storage media.

Vizdrik, G.; Ducharme, S.; Fridkin, V. M.; Yudin, S. G.

2003-09-01

244

Effect of Ni doping on ferroelectric and dielectric properties of strontium barium niobate crystals  

NASA Astrophysics Data System (ADS)

The influence of Ni doping on the ferroelectric and dielectric properties have been examined in Sr0.61Ba0.39Nb2O6 (SBN:61) relaxor crystals. The dopants introduced into SBN:61 crystals promote the switching process by reducing the value of threshold nucleation field, and thus coercive field. We present real-time studies of domain nucleation and growth processes in doped SBN:61 by the nematic liquid crystal (NLC) decoration technique. The broad phase transition and low-frequency dielectric dispersion that are exhibited by doped SBN:61 samples have a strong link to the configuration of the ferroelectrics microdomains, which in turn is strongly determined by Ni ions concentration.

Matyjasek, K.; Wolska, K.; Kaczmarek, S. M.; Subocz, J.; Ivleva, L.

2012-01-01

245

Possible ferroelectricity in perovskite oxynitride SrTaO2N epitaxial thin films  

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

246

Possible ferroelectricity in perovskite oxynitride SrTaO2N epitaxial thin films.  

PubMed

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 (10(1)-10(2)?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. PMID:24832473

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

2014-01-01

247

Possible ferroelectricity in perovskite oxynitride SrTaO2N epitaxial thin films  

PubMed Central

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.

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

2014-01-01

248

Continuously-tuned tunneling behaviors of ferroelectric tunnel junctions based on BaTiO3/La0.67Sr0.33MnO3 heterostructure  

NASA Astrophysics Data System (ADS)

In this work, we fabricate BaTiO3/La0.67Sr0.33MnO3 (BTO/LSMO) ferroelectric tunnel junction on (001) SrTiO3 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 102 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.

Ou, Xin; Xu, Bo; Gong, Changjie; Lan, Xuexin; Yin, Qiaonan; Xia, Yidong; Yin, Jiang; Liu, Zhiguo

2014-05-01

249

Poling and Depoling Effects on Dielectric Properties and Domain Structures in Relaxor 24Pb(In1/2Nb1/2)O3--46Pb(Mg1/3Nb2/3)O3--30PbTiO3 near a Morphotropic Phase Boundary Composition  

NASA Astrophysics Data System (ADS)

The temperature dependence of the complex relative permittivity in a relaxor ferroelectric solid solution 24Pb(In1/2Nb1/2)O3--46Pb(Mg1/3Nb2/3)O3--30PbTiO3 (PIN--PMN--PT) crystal poled and depoled was measured from room temperature to 200 °C at various frequencies. The poled sample exhibits transitions from the ferroelectric (FE) phase to the relaxor (RE) phase on heating, and after that, the depoled one exhibits those from the RE phase to the glassy freezing phase on cooling. An RE-type dielectric dispersion with a weak frequency (f) dependence was observed. Such a dielectric dispersion in the RE state was found to be based on tweed domain structures observed by polarization light microscopy (PLM) and piezoelectric force microscopy (PFM) due to the competition between the antiferroelectric (AFE) and FE coupling in the RE state. The temperature dependence of complex permittivity with resonance- and relaxor-type dielectric dispersions in the poled and depoled samples was characterized by hierarchical domain structures.

Hidayah, Nur; Yasuda, Naohiko; Ohwa, Hidehiro; Tachi, Yoshihito; Yamashita, Yohachi; Iwata, Makoto

2012-09-01

250

Basic Studies on Templated Grain Growth of Relaxor Ferroelectric Crystals and Textured Ceramics.  

National Technical Information Service (NTIS)

Templated grain growth (TGG) enables the relatively low cost fabrication of textured ceramics with single crystal-like properties, as well as single crystals. The resulting ceramics show texture levels up to 90%, and significant enhancements in the piezoe...

G. L. Messing S. Trolier-McKinstry

2003-01-01

251

Surface layer in relaxor ferroelectric PZN-4.5%PT single crystals  

NASA Astrophysics Data System (ADS)

The origin of the extremely broad peak at the lower 2? side of the main (002) rhombohedral x-ray peak in an unpoled (001)-cut Pb(Zn1/3Nb2/3)0.955Ti0.045O3 (PZN-4.5%PT) single crystal has been examined. This peak, located at about 2?~43°-44°, was absent on fractured surfaces of the crystal but reappeared when the fractured surfaces were polished mechanically. High-resolution synchrotron x-ray mesh scans revealed that the as-polished surface was covered with a ``deformed layer'' of heavily stressed rhombohedral phase of monoclinic symmetry having its c axis lying perpendicular to the surface. This deformed phase can be structurally likened to one full of ``incipient monoclinic nuclei/phases,'' which are microscopic in size and subject to intense compression in the plane of the surface. With a given polishing direction, this surface layer showed parallel domain patterns when viewed under the polarized light microscope. This surface layer could be largely eliminated by appropriate poling at 0.7-1.5 kV/mm at room temperature but became resistant to poling after annealing.

Chang, W. S.; Shanthi, M.; Rajan, K. K.; Lim, L. C.; Wang, F. T.; Tseng, C. T.; Tu, C. S.; Yang, Ping; Moser, H. O.

2007-06-01

252

Dynamical Properties of Relaxor Ferroelectric Lead Scandium Tantalate Probed by Micro-Brillouin Scattering  

NASA Astrophysics Data System (ADS)

We report the Brillouin scattering of a disordered Pb(Sc1/2Ta1/2)O3 crystal with degree of order S=0.29. In z(x,x+y)=\\bar{Z} scattering geometry, the broad minimum of longitudinal acoustic mode (LA) shifts and the broad maximum of LA width were observed around 245 K corresponing to the maximum temperature Tm of low frequency dielectric constant. Relaxation times were determined by assuming a complex elastic constant from LA modes, and they were attributed for the first time to the fluctuations of polar microregions. In addition, central peaks with marked temperature dependences were observed below 400 K showing a sharp anomaly at 293 K. Concerning specific heat, no anomaly was found for the as-grown crystal, while two broad anomalies around 293 and 270 K for PST (S=0.31), and only one marked anomaly at 293 K for PST (S=0.85) were observed in the cooling process, respectively. A two-phase transition model (Fm3m-R3m, Z=2; Pm3m-R3m, Z=1) was proposed to explain the experimental results.

Jiang, Fuming; Ko, Jae-Hyeon; Lushnikov, Sergey; Kojima, Seiji

2001-09-01

253

Long-range coupling interactions in ferroelectric sandwich structures  

Microsoft Academic Search

We study the ferroelectric system consisting of the sandwich structure (PbTiO3\\/BaTiO3\\/PbTiO3) by using the Ginzburg-Landau phenomenological theory, and emphasize the importance of the long-range coupling interaction to the ferroelectric behavior of the system. We find that after introducing the long-range coupling interaction to the ferroelectric behavior of the sandwich system, the average spontaneous polarization of the interlayer (BaTiO3) increases and

Jian Shen; Yu-Qiang Ma

2001-01-01

254

Two-dimensional ferroelectrics  

Microsoft Academic Search

The minimum size for a ferroelectric crystal has not been demonstrated experimentally because of difficulties in making thin films or small particles of sufficient quality. Langmuir-Blodgett deposition of crystalline films of vinylidene fluoride copolymers has produced high quality ferroelectric films as thin as 1 nm. These films permit the ultimate investigation of the finite-size effects on the atomic thickness scale

V. M. Fridkin; Stephen Ducharme; A. V. Bune; S. P. Palto; S. G. Yudin; L. M. Blinov

2000-01-01

255

Ferroelectric Materials: An Introduction  

NSDL National Science Digital Library

The discussion on phase field modeling and conserved order-disorder transformations is extended to phase transformations for non-conserved order parameters. The Allen-Cahn equation is presented. This lecture is intended to prepare students for the "Ferroelectric Materials: Ferroelectric Kinetics Computer Lab."

Garcã­a, R. E.

2008-08-25

256

Dielectric and Ferroelectric Properties of Lead Lanthanum Zirconate Titanate Thin Films for Capacitive Energy Storage  

NASA Astrophysics Data System (ADS)

As the increasing requirement of alternative energy with less pollution influence and higher energy efficient, new energy source and related storage methods are hot topic nowadays. Capacitors that supply high instant power are one of the keys in this application for both economic and functional design aspects. To lower the cost and increases the volumetric efficiency and reliability, relaxor thin films are considered as one of the candidates of the next generation capacitors. The research mainly focuses on dielectric and ferroelectric properties of lead lanthanum zirconate titanate or Pb1-xLax(ZryTi1-y)O3 (PLZT, x/y/1-y) relaxor thin films deposited on silicon (Si) and nickel (Ni) substrates in a range of thickness with different bottom electrodes, e.g. Platinum (Pt) and LaNiO3 (LNO). The final fabricated PLZT film capacitors will show strong potential for the energy storage application. The method adopted is the acetic acid assisted sol-gel deposition for the PLZT thin films. The wet chemical process is cost-effective and easily to scale up for plant/industrial products. We investigated the different bottom electrode/substrate influence in structure, microstructure, phases/defects, and heat-treatment conditions to achieve the optimized PLZT thin films. Issues of basic physical size effects in the PLZT thin films were also investigated, including thickness effects in the dielectric and ferroelectric properties of the films in a wide range of temperatures, the phase transition of the thin-film relaxors, lanthanum content effect, electrode-dielectric junction, misfit strain effect, etc. Based on the results and analysis, optimum PLZT film capacitors can be determined of proper substrate/electrode/dielectric that achieves the desired dielectric properties required for different applications, especially a more cost-effective method to develop volumetrically efficient capacitors with high charge density, energy density, dielectric breakdown strength, energy storage efficiency, and low dielectric loss, leakage current density.

Tong, Sheng

257

Relaxor-PT single crystals for broad bandwidth, high power sonar projectors  

NASA Astrophysics Data System (ADS)

The high piezoelectric response of the ferroelectric relaxor (1 - x)Pb(Mg1/3Nb2/3)O3 - xPbTiO3 (PMNT) in single crystal form has generated significant interest in producing broad bandwidth SONAR systems. Both the piezoelectric coefficient (d33 > 2000 pC/N) and coupling coefficient (k33 > 0.90) are superior to those of conventional piezoelectric ceramics. Within the context of a high power acoustic projector, its high losses and low temperature stability have limited its development. Second generation single crystals with compositions modified from the base PMNT have been recently developed to decrease the electromechanical losses and mitigate the thermal property dependence. In this work, the electromechanical properties were measured using single crystals which have been modified in various ways. The modified crystals exhibit electromechanically "hard" behavior with lower losses (tan delta = 0.1--0.2% and QM = 230--950) than unmodified PMNT (tan delta = 0.26% and QM = 190). The measured d33 values of modified single crystals (d33 = 760--1490 pm/V) are also lower than unmodified PMNT (d33 = 1540 pm/V), but the lower piezoelectric response is compensated by the greater stability of the modified single crystals. These modified single crystal properties were also compared to conventional high power piezoelectric ceramics ( d33 = 240 pm/V and QM = 1050) to show similar losses but significantly greater response in the modified PMNT single crystals. Although most piezoelectric materials are measured under small signal conditions (small signal defined by a completely linear relationship between the input and output signals), the high power nature of SONAR projectors demands that these modified single crystals also be evaluated under high power conditions. A test procedure was developed to measure the electromechanical properties of each material as a function of applied electric field over a frequency range which includes the resonance frequency. Modified single crystals showed twice the dynamic strain of unmodified PMNT as a function of electric field, and in many cases also showed greater maximum strain at failure (0.3% compared to 0.15% for unmodified PMNT). When QM was measured as a function of drive level, it was shown to sharply decrease under high dynamic strain. Modified single crystals with greater small signal QM values than unmodified PMNT maintain higher QM values under high drive, with Q M = 50--150 immediately prior to sample failure (Q M = 20 for base PMNT immediately prior to failure). The temperature dependence of modified PMNT single crystal electromechanical properties was also determined, and it was shown that modified crystals possess greater property stability than unmodified PMNT. While the base composition shows a limiting rhombohedral-tetragonal transition at 95 °C, modified single crystals using ternary PIN and PZT components show increased transition temperatures of 125 °C and 144 °C, respectively. The greater phase stability of the PIN ternary crystal was also examined through the coercive field, which was shown to be much greater than that of unmodified PMNT over the temperature range of interest (Ec = 5 kV/cm and 2 kV/cm, respectively, at room temperature). From the combined set of property measurements, the heat generation of each material was predicted for an arbitrary projector device. As a consequence of the lower losses, modified single crystals showed as little as 25% of the heat generation value for unmodified PMNT single crystals. Using this prediction as a performance metric, the crystals with the lowest heat generation were selected for device testing. Transducers with base PMNT and modified single crystals were designed using a finite element modeling approach. This model predicted approximately two octaves of bandwidth for the transducer geometry under investigation. A 5 dB decrease in acoustic output was observed when moving from base PMNT to highly modified crystals, but that result does not account for nonlinear material behavior. Transducers fabricated using mod

Sherlock, Nevin P.

258

Magnetoelectric effects in oxide magnetic tunnel junctions with ferroelectric barriers  

NASA Astrophysics Data System (ADS)

Functional properties of magnetic tunnel junction can be enhanced by employing a ferroelectric material as the barrier layer. We report on La0.7Sr0.3MnO3(LSMO)/BaTiO3(BTO)/LSMO magnetic tunnel junctions(MTJ) with BTO ferroelectric tunnel barrier. Switching BTO ferroelectric polarization influences the tunneling magnetoresistance (TMR) achieving two different r resistance states for each magnetic state (parallel or antiparallel) of the magnetization of the electrodes . The voltage dependence of the differential conductance obtained from IV curves displays oscillations whose period depends on the BTO electric polarization. This unusual behavior could be related to the presence of an induced magnetic moment in BTO ferroelectric barrier detected by XMCD measurements. These results reveal that spin polarization, and its tunneling conductance can be electrically tuned through reversal of the ferroelectric polarization of the barrier.

Tornos, Javier; Liu, Y. H.; Te Velthuis, S. G. E.; Fitzsimmons, M. R.; Rivera, A.; Lopez Anton, R.; Sanchez Santolino, G.; Varela Del Arco, M.; Nemes, N. M.; Pennycook, S. J.; Sefrioui, Z.; Yebra, C. Leon; Santamaria, J.

2013-03-01

259

Ferromagnetic, ferroelectric, and fatigue behavior of (111)-oriented BiFeO3/(Bi1/2Na1/2)TiO3 lead-free bilayered thin films  

NASA Astrophysics Data System (ADS)

Lead-free bilayered thin films consisting of BiFeO3 (BFO) and (Bi1/2Na1/2)TiO3 (BNT) nanolayers were deposited on the Pt/TiO2/SiO2/Si substrate by radio frequency sputtering. The bilayered BFO/BNT film exhibits a strong (111) orientation and much enhanced ferroelectric and magnetic properties (2Pr=52.2 ?C/cm2, 2Ec=554.0 kV/cm, 2Ms=96.0 emu/cm3, and 2Hc=253.2 Oe) as compared to those of the single layer BNT and BFO thin films, together with an almost fatigue-free polarization behavior. Although space charges occur at the interface between the constituent nanolayers, as confirmed by the frequency dispersion of capacitance, the bottom BNT nanolayer appears to promote the growth and crystallization of BFO layer, largely responsible for the observed ferroelectric and magnetic behavior.

Wu, Jiagang; Kang, Guangqing; Liu, Huajun; Wang, John

2009-04-01

260

Effects of the sintering temperature on the diffused phase transition and the spin-glassy behavior in Pb{sub 0.95}La{sub 0.05}(Fe{sub 2/3}W{sub 1/3}){sub 0.65}Ti{sub 0.35}O{sub 3} ceramics  

SciTech Connect

In this paper, the effect of the sintering temperature on the low-field dielectric behavior of nonstoichiometric Pb{sub 0.95}La{sub 0.05}(Fe{sub 2/3}W{sub 1/3}){sub 0.65}Ti{sub 0.35}O{sub 3} relaxor ferroelectrics is investigated. The x-ray patterns and the scanning electron microscope images are used to detect the pyrochlore phase and the perovskite structure. The electric properties of the resistivity, the space charge polarization, the temperature-dependent dielectric constant and dielectric loss are discussed. The diffused phase transition and the ordering state are fitted and discussed by using the empirical law and two ordering models. Furthermore, the glassy behavior is determined by using the Curie-Weiss law and the spin-glass model. According to the experimental data and fitting results, the dielectric picture is changed from the short range order relaxorlike behavior to the long range order normal ferroelectric state as increasing the sintering temperature and the glassy behavior is weakened at the lowest and highest sintering temperature at which the pyrochlore phase PWO{sub 4} is induced. Therefore, it is suggested that the 1:1 ordered domain is enhanced by increasing the sintering temperature and the glassy behavior is related to not only the ordering degree also the polar defect pairs. For more ordering degree and polar defect pairs, the glassy is weakened and the correlation of neighboring polar microregions is enhanced.

Hong, Cheng-Shong [Department of Electronic Engineering, National Kaohsiung Normal University, Kaohsiung County 824, Taiwan (China); Chu, Sheng-Yuan [Department of Electrical Engineering, National Cheng Kung University, Tainan 70101, Taiwan (China); Advanced Optoelectronic Technology Center, National Cheng Kung University, Tainan 70101, Taiwan (China); Center for Micro/Nano Science and Technology, National Cheng Kung University, Tainan 70101, Taiwan (China); Hsu, Chi-Cheng [Department of Electrical Engineering, National Cheng Kung University, Tainan 70101, Taiwan (China)

2010-05-15

261

Ferroelectric switching of elastin.  

PubMed

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

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

262

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

NASA Astrophysics Data System (ADS)

Single-phase Zn 0.95- xCu xLi 0.05O thin films have been prepared on Pt (1 1 1)/Ti/SiO 2 substrates by reactive magnetron sputtering method. The XRD, XPS and absorption measurements confirmed the polycrystalline nature of the films and the substitution of Zn 2+ by Cu 2+ ions. The sputtered Zn 0.90Cu 0.05Li 0.05O film shows multiferroic properties exhibiting a saturated ferroelectric loop with a remanent polarization of 6 ?C/cm 2 and a saturated loop with a saturation magnetization of 0.43 ? B/Cu at room temperature. The origins of the ferromagnetism and ferroelectricity in these films are discussed.

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

2010-03-01

263

Investigation of ferroelectric liquid crystal orientation in the silica microcapillaries  

NASA Astrophysics Data System (ADS)

In the paper we present our recent results concerning the orientation of ferroelectric liquid crystal molecules inside silica micro capillaries. We have infiltrated the silica micro capillaries with experimental ferroelectric liquid crystal material W-260K synthesized in the Military University of Technology. The infiltrated micro capillaries were observed under the polarization microscope while both a polarizer and an analyzer were crossed. The studies on the orientation of ferroelectric liquid crystal molecules may contribute to further studies on behavior of this group of liquid crystal materials inside photonic crystal fiber. The obtained results may lead to design of a new type of fast optical fiber sensors.

Budaszewski, D.; Doma?ski, A. W.; Woli?ski, T. R.

2013-05-01

264

Wireless ferroelectric resonating sensor.  

PubMed

This paper presents a passive wireless resonating sensor that is based on a ferroelectric varactor. The sensor replies with its data at an intermodulation frequency when a reader device illuminates it at 2 closely located frequencies. The paper derives a theoretical equation for the response of such a sensor, verifies the theory by simulations, and demonstrates a temperature sensor based on a ferroelectric varactor. PMID:20378440

Viikari, Ville; Seppa, Heikki; Mattila, Tomi; Alastalo, Ari

2010-04-01

265

Ferroelectric properties in Mn-modified BiFeO3-BaTiO3 ceramics  

NASA Astrophysics Data System (ADS)

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.

Dai, Zhonghua; Akishige, Yukikuni

2014-12-01

266

Ferroelectric and Antiferroelectric Liquid Crystals  

Microsoft Academic Search

Ferroelectric liquid crystals have been a major research topic since 30 years. However, when it comes to liquid crystals, the term “ferroelectric” is strongly ambiguous and frequently not only leads to confusion and misunderstanding but also obscures the basic concepts.The property of ferroelectricity in liquid crystals was first claimed in 1975. Five years later so-called surface-stabilized ferroelectric liquid crystals were

SVEN T. LAGERWALL

2004-01-01

267

Enhanced dielectric, ferroelectric, and electrostrictive properties of Pb(Mg1/3Nb2/3)0.9Ti0.1O3 ceramics by ZnO modification  

NASA Astrophysics Data System (ADS)

The effects of ZnO modification on the dielectric, ferroelectric, and electrostrictive properties of 0.9Pb(Mg1/3Nb2/3)O3-0.1PbTiO3 (PMNT) ceramics are systematically studied in this work. The PMNT/xZnO (with x = 0, 0.4, 2.0, 4.0, and 11.0 mol. %) ceramics of complex perovskite structure were prepared by solid state reaction and sintering process. It is found that the maximum value of the dielectric constant decreases with increasing ZnO amount up to x = 4.0 mol. %, and then significantly increases with x = 11.0 mol. %. The temperature of maximum dielectric constant tends to increase, while the diffuseness of the dielectric peak is reduced, with increasing ZnO content. The remanent polarization and the coercive field increase with increasing ZnO concentration. The induced strain and the electrostrictive coefficient reach the maximum values of 0.10% (at E = 10 kV/cm) and 12.94 × 10-16 m2/V2, respectively, with x = 2.0 mol. % ZnO. The ceramic doped with a high ZnO content (11.0 mol. %) exhibits a macroscopically polar phase with a well-developed ferroelectric hysteresis loop and butterfly-shaped bipolar piezoelectric response. This enhanced long-range polarization and the resulting properties are attributed to the effects of the partial substitution of Zn2+ for Mg2+, which favors a higher degree of polar order and a lower degree of relaxor behavior.

Promsawat, Methee; Watcharapasorn, Anucha; Tailor, Hamel N.; Jiansirisomboon, Sukanda; Ye, Zuo-Guang

2013-05-01

268

Ferroelectric Langmuir-Blodgett films  

Microsoft Academic Search

The ferroelectric Langmuir-Blodgett films are prepared and investigated for the first time The films are prepared from the ferroelectric copolymer of vinylidene fluoride with trifluorethylene The films with the thickness off 150 Å show the pyroelectric effect being measured along the polar C-axis perpendicular to the substrate surface, partial remnant polarization switching and ferroelectric phase transition of the first order,

S. Palto; L. Blinov; A. Bune; E. Dubovik; V. Fridkin; N. Petukhova; K. Verkhovskaya; S. Yudin

1995-01-01

269

Ferroelectric langmuir-blodgett films  

Microsoft Academic Search

Ferroelectric Langmuir-Blodgett films are prepared and investigated for the first time. The films are prepared from the ferroelectric copolymer of vinylidene fluoride with trifluorethylene. Films with a thickness of 150Å show a pyroelectric effect, remnant polarization switching and a ferroelectric phase transition of the first order, characterized by temperature hysteresis.

S. Palto; L. Blinov; A. Bune; E. Dubovik; V. Fridkin; N. Petukhova; K. Verkhovskaya; S. Yudin

1996-01-01

270

Flexoelectricity in Nanoscale Ferroelectrics  

NASA Astrophysics Data System (ADS)

All ferroelectrics are piezoelectric and thus have an intrinsic coupling between polarization and strain. There exists an additional electromechanical coupling, however, between polarization and strain gradients. Strain gradients are intrinsically vectorial fields and, therefore, they can in principle be used to modify both the orientation and the sign of the polarization, thanks to the coupling known as flexoelectricity. Flexoelectricity is possible even in paraelectric materials, but is generally stronger in ferroelectrics on account of their high permittivity (the flexoelectric coefficient is proportional to the dielectric constant). Moreover, strain gradients can be large at the nanoscale due to the smallness of the relaxation length and, accordingly, strong flexoelectric effects can be expected in nanoscale ferroelectrics. In this talk we will present two recent results that highlight the above features. In the first part, I will show how polarization tilting can be achieved in a nominally tetragonal ferroelectric (PbTiO3) thanks to the internal flexoelectric fields generated in nano-twinned epitaxial thin films. Flexoelectricity thus offers a purely physical means of achieving rotated polarizations, which are thought to be useful for enhanced piezoelectricity. In the second part, we will show how the large strain gradients generated by pushing the sharp tip of an atomic force microscope against the surface of a thin ferroelectric film can be used to actively switch its polarity by 180^o. This enables a new concept for ``multiferroic'' memory operation in which the memory bits are written mechanically and read electrically.

Catalan, Gustau

2012-02-01

271

Polarization fatigue of organic ferroelectric capacitors  

PubMed Central

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.

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

272

Polarization fatigue of organic ferroelectric capacitors.  

PubMed

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 10(8) times, approaching the programming cycle endurance of its inorganic ferroelectric counterparts. PMID:24861542

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

273

Applications of modern ferroelectrics.  

PubMed

Long viewed as a topic in classical physics, ferroelectricity can be described by a quantum mechanical ab initio theory. Thin-film nanoscale device structures integrated onto Si chips have made inroads into the semiconductor industry. Recent prototype applications include ultrafast switching, cheap room-temperature magnetic-field detectors, piezoelectric nanotubes for microfluidic systems, electrocaloric coolers for computers, phased-array radar, and three-dimensional trenched capacitors for dynamic random access memories. Terabit-per-square-inch ferroelectric arrays of lead zirconate titanate have been reported on Pt nanowire interconnects and nanorings with 5-nanometer diameters. Finally, electron emission from ferroelectrics yields cheap, high-power microwave devices and miniature x-ray and neutron sources. PMID:17303745

Scott, J F

2007-02-16

274

A ferroelectric memristor  

NASA Astrophysics Data System (ADS)

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.

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

275

Far-infrared soft-mode behavior in PbSc1/2Ta1/2O3 thin films  

NASA Astrophysics Data System (ADS)

Temperature dependences of the optic phonons in PbSc1/2Ta1/2O3 (PST) sol-gel films deposited on sapphire substrates were studied by means of Fourier transform far-infrared transmission spectroscopy in the temperature range of 20-900 K. Four films displaying different B-site order with both ferroelectric and relaxor behavior were studied. In all cases the TO mode near 80 cm-1 at 10 K softens on heating to ~45 cm-1 following the Cochran law with extrapolated critical temperature near 700 K which is 400 K above the temperature of dielectric maximum, Tm. Above 600 K the TO1 mode remains stabile. This mode can be assigned to the A1 component of the ferroelectric soft-mode inside polar clusters which form below the Burns temperature near 700 K. In the ordered PST film another mode activates below Tm in the infrared spectra near 60 cm-1, also exhibiting an anomalous temperature dependence due to its coupling with the former mode. It is assigned to the A1 component of the F2g Raman active mode. The central mode, which appears below the Burns temperature in the terahertz range, is assigned to the dynamics of polar clusters. It slows down on cooling and vanishes from our spectral range below Tm. Another overdamped excitation assigned to the E component of the soft mode appears near 30 cm-1 at low temperature.

Kamba, S.; Berta, M.; Kempa, M.; Hlinka, J.; Petzelt, J.; Brinkman, K.; Setter, N.

2005-10-01

276

Nanostructured ferroelectrics: fabrication and structure-property relations.  

PubMed

With the continued demand for ultrahigh density ferroelectric data storage applications, it is becoming increasingly important to scale the dimension of ferroelectrics down to the nanometer-scale region and to thoroughly understand the effects of miniaturization on the materials properties. Upon reduction of the physical dimension of the material, the change in physical properties associated with size reduction becomes extremely difficult to characterize and to understand because of a complicated interplay between structures, surface properties, strain effects from substrates, domain nucleation, and wall motions. In this Review, the recent progress in fabrication and structure-property relations of nanostructured ferroelectric oxides is summarized. Various fabrication approaches are reviewed, with special emphasis on a newly developed stencil-based method for fabricating ferroelectric nanocapacitors, and advantages and limitations of the processes are discussed. Stress-induced evolutions of domain structures upon reduction of the dimension of the material and their implications on the electrical properties are discussed in detail. Distinct domain nucleation, growth, and propagation behaviors in nanometer-scale ferroelectric capacitors are discussed and compared to those of micrometer-scale counterparts. The structural effect of ferroelectric nanocapacitors on the domain switching behavior and cross-talk between neighboring capacitors under external electric field is reviewed. PMID:21919083

Han, Hee; Kim, Yunseok; Alexe, Marin; Hesse, Dietrich; Lee, Woo

2011-10-25

277

Ferroelectric tunneling element and memory applications which utilize the tunneling element  

DOEpatents

A tunneling element includes a thin film layer of ferroelectric material and a pair of dissimilar electrically-conductive layers disposed on opposite sides of the ferroelectric layer. Because of the dissimilarity in composition or construction between the electrically-conductive layers, the electron transport behavior of the electrically-conductive layers is polarization dependent when the tunneling element is below the Curie temperature of the layer of ferroelectric material. The element can be used as a basis of compact 1R type non-volatile random access memory (RAM). The advantages include extremely simple architecture, ultimate scalability and fast access times generic for all ferroelectric memories.

Kalinin, Sergei V. (Knoxville, TN) [Knoxville, TN; Christen, Hans M. (Knoxville, TN) [Knoxville, TN; Baddorf, Arthur P. (Knoxville, TN) [Knoxville, TN; Meunier, Vincent (Knoxville, TN) [Knoxville, TN; Lee, Ho Nyung (Oak Ridge, TN) [Oak Ridge, TN

2010-07-20

278

Coupling of ferroelectricity and ferromagnetism through Coulomb blockade in composite multiferroics  

NASA Astrophysics Data System (ADS)

Composite multiferroics are materials exhibiting the interplay of ferroelectricity, magnetism, and strong electron correlations. Typical example—magnetic nano grains embedded in a ferroelectric matrix. Coupling of ferroelectric and ferromagnetic degrees of freedom in these materials is due to the influence of ferroelectric matrix on the exchange coupling constant via screening of the intragrain and intergrain Coulomb interaction. Cooling typical magnetic materials the ordered state appears at lower temperatures than the disordered state. We show that in composite multiferroics the ordered magnetic phase may appear at higher temperatures than the magnetically disordered phase. In nonmagnetic materials such a behavior is known as inverse phase transition.

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

2014-05-01

279

Dielectric characteristics of the relaxor state of the perovskite ceramics 0.9(Na1 - x K x Bi)1/2TiO3-0.1Bi(ZnTi)1/2O3 near the morphotropic phase boundary  

NASA Astrophysics Data System (ADS)

X-ray diffraction investigations have revealed that, in the system of solid solutions 0.9(Na1 - x K x Bi)1/2TiO3-0.1Bi(ZnTi)1/2O3, there is a morphotropic phase boundary in the potassium concentration range of x ? 0.25, which separates the regions of compositions with rhombohedral ( R3 c) and tetragonal ( P4 mm) structures. It has been shown that, in the vicinity of this boundary, ceramic samples of the studied system exhibit properties of relaxor ferroelectrics. The results of the investigation into the dielectric properties of relaxor ceramics of the composition x = 0.3 with the use of the impedance spectra measured in the frequency range from 25 to 106 Hz at temperatures from 100 to 900 K have been presented. It has been found that, in the temperature region of the existence of the relaxor state lying below the temperature corresponding to the maximum of the real part of the permittivity ( T' m = 550 K), the dielectric polarization is determined by the sum of the contributions from the matrix and dipole clusters. The temperature dependence of the contribution from the clusters, which is determined by the kinetics of their formation and freezing, is characterized by a curve with the maximum at approximately 400 K. The process of freezing of dipole clusters occurs over an extended temperature range of more than 200 K.

Olekhnovich, N. M.; Pushkarev, A. V.; Radyush, Yu. V.

2013-10-01

280

A Investigation of the Dielectric and Hysteresis Properties of Plzt Ferroelectric and Multilayer Composite Thin Films.  

NASA Astrophysics Data System (ADS)

The dielectric and hysteresis properties of ferroelectric and multilayer composite thin films were investigated. PLZT ferroelectrics were produced in bulk ceramic and thin film form from the same acetate precursor solutions in order to compare their electrical and physical properties. Bulk ceramics were hot pressed from chemically coprecipitated powders, and thin films were fabricated by spin and dip coating on Ag and Pt-coated Si substrates. Internal film stress from thermal expansion mismatch between films and substrates was found to contribute to differences in electrical properties and Curie temperatures between the thin film and bulk materials as were interface layer effects, grain size and mechanical clamping from the substrates. Rapid thermal processing (RTP) of PLZT thin films using an automated spin coat reactor was found to improve thin film dielectric and hysteresis properties as well as enhance perovskite phase formation, induce preferred (110) and (111) orientations, decrease grain size and increase microstructural uniformity. RTP films were compared with manually spin coated thin films with conventional furnace pyrolysis (CFP) in order to isolate the effects of heating rate from deposition technique. Heating rates of at least 70^circC per second were obtained by RTP versus 35^circC per second for CFP. The development of composite thin films further optimized PLZT thin film properties. Improved antiferroelectric -to-ferroelectric domain switching with decreased ferroelectric coercive field, increased induced polarization with decreased coercivity and polarization remanence for relaxor-type composites and increased hysteresis loop squareness for ferroelectric memory materials were among the advances compared with films of homogeneous PLZT composition. Experimental dielectric and hysteresis properties were described by a series capacitor model consisting of the linear and nonlinear properties of the individual composite components.

Dausch, David Edward

1995-01-01

281

Electron paramagnetic resonance investigation of polar nanoregions mobility in the relaxor PbMg1/3Nb2/3O3 and solid solutions PbMg1/3Nb2/3O3 - PbTiO3  

NASA Astrophysics Data System (ADS)

Electron paramagnetic resonance (EPR) of Mn2+ and Fe3+ ions has been used as a probe of local static and dynamic lattice distortions in the relaxor ferroelectric PbMg1/3Nb2/3O3 (PMN) and solid solutions (1-x)PbMg1/3Nb2/3O3 - xPbTiO3 (x = 0.075-0.33) at temperatures from 290 to 800 K. We have found that the spectrum of the both ions in PMN contains two components: One component corresponds to the resonances from the lattice regions where the perovskite cubic structure is distorted statically while the second component corresponds to the regions where ionic displacements undergo significant dynamic fluctuations. The EPR spectrum from these lattice regions shows the motional narrowing behavior at 350-500 K. We assign these regions with reorientable polar nanoregions responsible for the dielectric relaxation in PMN. From the motional narrowing of the spectral lines, we have determined parameters of the Vogel--Fulcher law describing the rate of ionic hopping between symmetrically equivalent off-center positions. These parameters (Ea = 840-880 K, ?0 ~ 10-13 s, Tg = 220 K) are in a satisfactory agreement with those reported for the dielectric relaxation. The fraction of polar nanoregions in PMN determined from the EPR intensity is about 20% to 30%. An addition of PbTiO3 to PMN decreases total volume of the polar nanoregions and also suppresses their reorientational dynamics. The EPR spectra do not change in the temperature range from 500 to 800 K, including the temperatures far above the Burns temperature 620 K.

Glinchuk, Maya D.; Laguta, Valentin V.; Yurchenko, Lesya P.; Rosa, Jan; Jastrabik, Lubomir; Eremkin, Vladimir V.; Smotrakov, Valery G.

2012-01-01

282

SrBi4Ti4O15 thin films and their ferroelectric fatigue behaviors under varying switching pulse widths and frequencies  

NASA Astrophysics Data System (ADS)

Polycrystalline ferroelectric SrBi4Ti4O15 thin films were prepared on Pt-coated silicon substrates by pulsed laser deposition. Structures of the films were analyzed by x-ray diffraction, atomic force microscopy (AFM) and scanning electron microscopy. At an applied field of 275 kV/cm, the films showed good hysteresis loops with remnant polarization (Pr), saturated polarization (Ps) and coercive field (Ec) of 3.11 ?C/cm2, 7.81 ?C/cm2 and 68 kV/cm, respectively. At 120 kV/cm switching pulse field, fatigue tests were carried out systematically by varying the switching pulsewidth with a fixed duty cycle and with a fixed switching period, respectively. A gradual increase followed by an abrupt increase of the fatigue rate was observed with the increase of the switching pulsewidth. Field-induced defect diffusion was used to explain the results.

Zhang, Shan-Tao; Yang, Bin; Chen, Yan-Feng; Liu, Zhi-Guo; Yin, Xiao-Bo; Wang, Yuan; Wang, Mu; Ming, Nai-Ben

2002-03-01

283

Theory of Dynamical Ferroelectricity.  

National Technical Information Service (NTIS)

This paper gives a dynamical theory of ferroelectricity. The theory takes into account the transient effects due to domain switching and dipole dynamics. A specific representation is derived for departures from the virgin state which is taken to be a natu...

P. J. Chen

1983-01-01

284

Quantum Ferroelectric Pressure Sensor.  

National Technical Information Service (NTIS)

A study was undertaken to find a material that could be used as a temperature-independent, magnetic-field-independent, capacitive pressure sensor for applications below about 10 K. Although the dielectric constant in quantum ferroelectrics is large and in...

W. N. Lawless C. F. Clark

1982-01-01

285

Nanodomain faceting in ferroelectrics  

Microsoft Academic Search

We show that after long times (24 h), individual circular domains in 50 nm thick (001) epitaxial films of ferroelectric lead zirconate titanate (PZT) develop facets due to the crystalline anisotropy, e.g. along (100) directions. This appears to be a creep process (Tybell et al 2002 Phys. Rev. Lett.89 097601; Paruch et al 2006 J. Appl. Phys. 100 051608) and

286

Polarization-independent aging in the relaxor 0.92PbMg1/3Nb2/3O3-0.08PbTiO3  

NASA Astrophysics Data System (ADS)

Spin-glass-like aging, showing rejuvenation upon cooling and a hole in susceptibility vs temperature at the aging temperature on warming, was found in the relaxor ferroelectric (PbMg1/3Nb2/3O3)0.92(PbTiO3)0.08 (PMN-PT 8%). The magnitude and form of the aging memory hole produced at zero field showed little sensitivity to the magnitude of the previously induced polarization, up to near saturation. This result is incompatible with any picture in which the glassy aging arises from interactions among polar nanodomains, which account for most of the polarization. The results therefore support a picture in which the glassy aging arises from degrees of freedom other than the orientation of polar nanodomains.

Colla, Eugene V.; Griffin, Philip; Delgado, Matthew; Weissman, M. B.; Long, Xifa; Ye, Zuo-Gang

2008-08-01

287

A new ferroelectric memory device, metal-ferroelectric-semiconductor transistor  

Microsoft Academic Search

The ferroelectric field effect has successfully been demonstrated on a bulk semiconductor (silicon) using a thin ferroelectric film of bismuth titanate (Bi4Ti3O12) deposited onto it by RF sputtering. A new memory device, the metal-ferroelectric-semiconductor transistor (MFST); has been fabricated. This device utilizes the remanent polarization of a ferroeletric thin film to control the surface conductivity of a bulk semiconductor substrate

Shu-Yau Wu

1974-01-01

288

Multiferroic behavior in CdCr2X4(X=S,Se)  

NASA Astrophysics Data System (ADS)

The recently discovered multiferroic material CdCr2S4 shows a coexistence of ferromagnetism and relaxor ferroelectricity together with a colossal magnetocapacitive effect. The complex dielectric permittivity of this compound and of the structurally related CdCr2Se4 was studied by means of broadband dielectric spectroscopy using different electrode materials. The observed magnetocapacitive coupling at the magnetic transition is driven by enormous changes of the relaxation dynamics induced by the development of magnetic order.

Hemberger, J.; Lunkenheimer, P.; Fichtl, R.; Weber, S.; Tsurkan, V.; Loidl, A.

2006-05-01

289

Multiferroic behavior in CdCr2X4(X=S,Se)  

Microsoft Academic Search

The recently discovered multiferroic material CdCr2S4 shows a coexistence of ferromagnetism and relaxor ferroelectricity together with a colossal magnetocapacitive effect. The complex dielectric permittivity of this compound and of the structurally related CdCr2Se4 was studied by means of broadband dielectric spectroscopy using different electrode materials. The observed magnetocapacitive coupling at the magnetic transition is driven by enormous changes of the

J. Hemberger; P. Lunkenheimer; R. Fichtl; S. Weber; V. Tsurkan; A. Loidl

2006-01-01

290

Effect of A-site La and Ba doping on threshold field and characteristic temperatures of PbSc0.5Ta0.5O3 relaxor studied by acoustic emission  

NASA Astrophysics Data System (ADS)

The structural transitions in Pb1-xLaxSc(1+x)/2Ta(1-x)/2O3, x = 0.08 (PLST) relaxor crystals were studied by means of acoustic emission (AE) under an external electric field (E) and compared with those observed in pure PbSc0.5Ta0.5O3 (PST) and Pb0.78Ba0.22Sc0.5Ta0.5O3 (PBST) [E. Dul'kin et al., EPL 94, 57002 (2011)]. Similar to both the PST and PBST compounds, in zero field PLST exhibits AE corresponding to a para-to-antiferroelectric incommensurate phase transition at Tn = 276 K, lying in the vicinity of dielectric temperature maximum (Tm). This AE signal exhibits a nontrivial behavior when applying E resembling the electric-field-dependence of Tn previously observed for both the PST and PBST, namely, Tn initially decreases with the increase of E, attains a minimum at a threshold field Eth = 0.5 kV/cm, accompanied by a pronounced maximum of the AE count rate ? = 12 s-1, and then starts increasing as E enhances. The similarities and difference between PST, PLST, and PBST with respect to Tn, Eth, and ? are discussed from the viewpoint of three mechanisms: (i) chemically induced random local electric field due to the extra charge on the A-site ion, (ii) disturbance of the system of stereochemically active lone-pair electrons of Pb2+ by the isotropic outermost electron shell of substituting ion, and (iii) change in the tolerance factor and elastic field to the larger ionic radius of the substituting A-site ion due to the different radius of the substituting ion. The first two mechanisms influence the actual values of Tn and Eth, whereas the latter is shown to affect the normalized ?, indicating the fractions undergoing a field-induced crossover from a modulated antiferroelectric to a ferroelectric state. Creation of secondary random electric field, caused by doping-induced A-site-O ionic chemical bonding, is discussed.

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

2012-09-01

291

Ferroelectric studies of excessive Sm3+ containing perovskite PZT and pyrochlore biphase ceramics  

NASA Astrophysics Data System (ADS)

Polycrystalline samples of Sm3+ modified Pb1-x Sm2x/3 (Zr0.6Ti0.4) O3 (PSZT) ceramics (where x = 0.1, 0.2, 0.3, 0.4) have been prepared by a high energy ball milling technique, followed by calcination at 950°C and sintering at 1150°C. As x is increased more than 0.1 mole%, considerable secondary phase has been formed. This phase has been identified as pyrochlore Sm2Ti2O7 from its X-ray diffraction (XRD) peaks. The XRD studies also indicate that the perovskte phases of the present systems undergo a dopant induced phase transformation from rhombohedral to tetragonal strucure. All the samples exhibit diffuse but non-relaxor type ferroelectric phase transition. The results of dielectric and hysteresis studies of these materials are presented.

Babu, T. Anil; Ramesh, K. V.; Reddy, V. Raghavendra; Sastry, D. L.

2014-04-01

292

Study of physical properties of integrated ferroelectric/ferromagnetic heterostructures  

SciTech Connect

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.

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

293

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)

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.

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

2014-01-01

294

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

NASA Astrophysics Data System (ADS)

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.

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

2013-09-01

295

Local Structure in PMSN Across the Ferroelectric Phase Transition  

NASA Astrophysics Data System (ADS)

Local structure and ^93Nb ion displacement play vital roles in the ferroelectric polarization and phase transitions of solid solutions with composition (1-x)PbMg1/3Nb2/3O3 -- x PbSc1/2Nb1/2O3 (PMSN). Here, we report variable temperature, high field (17.6Tesla) ^93Nb MAS and 3QMAS NMR studies of PMSN with compositions between x = 0.6 and 0 (pure PMN). In PMSN, six narrow components and one broad peak were observed. Spectral assignments agree with previous reports [D.H.Zhou, G.L.Hoatson, R.L.Vold, J. Magn. Reson. 167 (2004) 242-252 and references therein]. The broad peak is resolved only at temperatures below the dielectric susceptibility maximum (i.e., T ferroelectric relaxor phase transition, and allow conclusions to be drawn regarding the chemical composition of polar nanoclusters. In collaboration with Gina Hoatson and Murugesan Vijayakumar, College of William & Mary.

Vold, Robert

2006-11-01

296

Intrinsic Ferroelectric Coercive Field  

Microsoft Academic Search

The Landau-Ginzburg theory of ferroelectricity predicts the intrinsic coercive field for polarization reversal, but the observed extrinsic coercive field is always much smaller as a result of nucleation, dynamic processes not covered by the static theory. We have realized the intrinsic coercive field for the first time, in two-dimensional Langmuir-Blodgett polymer films as thin as 1 nm. The measured coercive

Stephen Ducharme; V. M. Fridkin; A. V. Bune; S. P. Palto; L. M. Blinov; N. N. Petukhova; S. G. Yudin

2000-01-01

297

SOFT MODE ANOMALIES IN THE PEROVSKITE RELAXOR Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}  

SciTech Connect

Neutron inelastic scattering measurements of the polar TO phonon mode in the cubic relaxor Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}, at room temperature, reveal anomalous behavior similar to that recently observed in Pb(Zn{sub 1/3}Nb{sub 2/3}){sub 0.92}Ti{sub 0.08}O{sub 3} in which the optic branch appears to drop precipitously into the acoustic branch at a finite value of the momentum transfer q = 0.2 {angstrom}{sub {minus}1}, measured from the zone center. By contrast, a recent neutron study indicates that PMN exhibits a normal TO phonon dispersion at 800 K. The authors speculate this behavior is common to all relaxor materials, and is the result of the presence of nanometer-scale polarized domains in the crystal that form below a temperature T{sub d}, which effectively prevent the propagation of long wavelength (q = 0) phonons.

GEHRING,P.M.; VAKRUSHEV,S.B.; SHIRANE,G.

2000-03-09

298

Ferroelectric quantum criticality  

NASA Astrophysics Data System (ADS)

Paramagnets on the border of ferromagnetism at low temperatures are more subtle and complex than anticipated by the conventional theory of quantum critical phenomena. Could quantum criticality theory be more relevant in the corresponding case of quantum paraelectrics on the border of ferroelectricity? To address this question we have investigated the temperature dependence of the dielectric function of the displacive quantum paraelectrics SrTiO3, oxygen-18 substituted SrTiO3 and KTaO3. In all of these materials on the border of ferroelectricity we observe non-classical T2 temperature dependencies of the inverse dielectric function below 50 K, followed by anomalous upturns below a few kelvin extending into the millikelvin range. This non-classical behaviour can be understood quantitatively without adjustable parameters in terms of quantum criticality theory when extended to include the effects of long-range dipolar interactions and the coupling of the electric polarization field with acoustic phonons. The quantum critical regime in displacive ferroelectrics is thus strikingly different from that in the better-known ferromagnetic counterparts and offers unexpected prospects in the field of quantum phase transitions.

Rowley, S. E.; Spalek, L. J.; Smith, R. P.; Dean, M. P. M.; Itoh, M.; Scott, J. F.; Lonzarich, G. G.; Saxena, S. S.

2014-05-01

299

Hierarchical textures in ferroelectric crystals  

NASA Astrophysics Data System (ADS)

Some results from a new study of the relaxor-like material known as PST, lead scandium tantalate Pb(Sc(0.5)Ta(0.5)O3) are presented. The emphasis is on some novel electron optical results and techniques. It will be shown that the High Resolution Transmission Electron Microscopy techniques offer a new level of understanding of the nanostructure of PST.

Peng, Julin; Bursill, L. A.

300

Ferroelectric and dielectric properties of ferrite-ferroelectric ceramic composites  

SciTech Connect

Particulate composites of ferrite and ferroelectric phases with xNiFe{sub 2}O{sub 4} (NF) and (1 - x)Pb{sub 0.988}(Zr{sub 0.52}Ti{sub 0.48}){sub 0.976}Nb{sub 0.024}O{sub 3} (where x = 2, 10, 20, 30, 50, 70, and 100 wt. %) were prepared in situ by sol-gel method. The presence of a diphase composition was confirmed by X-ray diffraction while the microstructure of the composites was studied by scanning electron microscopy revealing a good mixing of the two phases and a good densification of the bulk ceramics. The dielectric permittivity shows usual dielectric dispersion behavior with increasing frequency due to Maxwell-Wagner interfacial polarization. AC conductivity measurements made in frequency range 1 Hz-1 MHz suggest that the conduction process is due to mixed polaron hopping. The effect of NF phase concentration on the P-E and M-H hysteresis behavior and dielectric properties of the composites was investigated. At low NF concentration a sharp ferro-paraelectric transition peak can be observed at around 360 Degree-Sign C while for higher NF concentrations a trend to a diffuse phase transition occurs. All the composite samples exhibit typical ferromagnetic hysteresis loops, indicating the presence of ordered magnetic structure.

Elena Ciomaga, Cristina; Maria Neagu, Alexandra; Valentin Pop, Mihai; Mitoseriu, Liliana [Faculty of Physics, 'Al. I. Cuza' University of Iasi 700506, Iasi (Romania); Airimioaei, Mirela [Faculty of Chemistry, 'Al. I. Cuza' University of Iasi 700506, Iasi, Romania and Dept. Chemistry and Process Engineering, University of Genoa, P-le Kennedy no. 1, I-16129, Genoa (Italy); Tascu, Sorin [RAMTECH Faculty of Physics, 'Al. I. Cuza' University of Iasi 700506 (Romania); Schileo, Giorgio [Christian Doppler Laboratory for Advanced Ferroic Oxides, Sheffield Hallam University, Howard Street, Sheffield S1 1WB (United Kingdom); Galassi, Carmen [CNR-ISTEC, Via Granarolo no. 64, I-48018 Faenza (Italy)

2013-02-21

301

Ferroelectric and dielectric properties of ferrite-ferroelectric ceramic composites  

NASA Astrophysics Data System (ADS)

Particulate composites of ferrite and ferroelectric phases with xNiFe2O4 (NF) and (1 - x)Pb0.988(Zr0.52Ti0.48)0.976Nb0.024O3 (where x = 2, 10, 20, 30, 50, 70, and 100 wt. %) were prepared in situ by sol-gel method. The presence of a diphase composition was confirmed by X-ray diffraction while the microstructure of the composites was studied by scanning electron microscopy revealing a good mixing of the two phases and a good densification of the bulk ceramics. The dielectric permittivity shows usual dielectric dispersion behavior with increasing frequency due to Maxwell-Wagner interfacial polarization. AC conductivity measurements made in frequency range 1 Hz-1 MHz suggest that the conduction process is due to mixed polaron hopping. The effect of NF phase concentration on the P-E and M-H hysteresis behavior and dielectric properties of the composites was investigated. At low NF concentration a sharp ferro-paraelectric transition peak can be observed at around 360 °C while for higher NF concentrations a trend to a diffuse phase transition occurs. All the composite samples exhibit typical ferromagnetic hysteresis loops, indicating the presence of ordered magnetic structure.

Elena Ciomaga, Cristina; Maria Neagu, Alexandra; Valentin Pop, Mihai; Airimioaei, Mirela; Tascu, Sorin; Schileo, Giorgio; Galassi, Carmen; Mitoseriu, Liliana

2013-02-01

302

Automated System Tests Ferroelectric Capacitors  

NASA Technical Reports Server (NTRS)

Polarization-switching parameters measured under computer control. Ferroelectric-capacitor-testing system applies voltage pulses and measures responses of ferroelectric capacitor to determine write; "time dependence of polarization," polarization-retention and fatigue characteristics of capacitor. Highly integrated setup quite flexible, versatile, and interactive, and allows convenient computer storage and analysis of data.

Lakata, Mark; Thakoor, Sarita

1994-01-01

303

Ferroelectricity in ultrathin perovskite films  

Microsoft Academic Search

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

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

2004-01-01

304

From spin induced ferroelectricity to spin and dipolar glass in a triangular lattice: The CuCr1-xVxO2 (0?x?0.5) delafossite  

NASA Astrophysics Data System (ADS)

The change from antiferromagnetism induced ferroelectricity to spin glass ferroelectric relaxor has been studied along the CuCr1-xVxO2 (0?x?0.5) solid solution of polycrystalline samples. As x increases from CuCrO2 (x=0) to CuCr0.82V0.18O2, it is found that the Néel temperature decreases from ˜24 K down to ˜13 K. This progressive weakening of the antiferromagnetism of CuCrO2 induces a rapid decrease of the spin induced ferroelectricity with polarization values going from ˜44 ?C/m2 down to ˜1.5 ?C/m2 for x=0.04 and x=0.08, respectively. Beyond x=0.18 (0.20?x?0.50), ac-magnetic susceptibility and magnetization measurements evidence a spin glass state while dielectric permittivity and polarization measurements point towards a relaxor behaviour. This shows that competing magnetic interactions in delafossites are an efficient way to transform a spin induced magnetoelectric into a multiglass (spin and dipolar) state.

Kumar, S.; Singh, K.; Miclau, M.; Simon, Ch.; Martin, C.; Maignan, A.

2013-07-01

305

CMOS Equivalent Model of Ferroelectric RAM  

Microsoft Academic Search

The current research work in the paper is the representation of FRAM (Ferroelectric Random Access Memory) as an equivalent Model of Ferroelectric memory cell in Spice Tool. This Equivalent CMOS based model is designed to work at par with the behaviour working of the FRAM. The crux of the design of ferroelectric capacitor in the Ferroelectric Random Access Memory lies

Parvinder S. Sandhu; Iqbaldeep Kaur; Amit Verma; Birinderjit S. Kalyan; Jagdeep Kaur; Sanyam Anand

2010-01-01

306

Mutual Ferromagnetic-Ferroelectric Coupling in Multiferroic Copper Doped ZnO  

SciTech Connect

A mutual ferromagnetic and ferroelectric coupling (multiferroic behavior) in Cu-doped ZnO is demonstrated via deterministic control of Cu doping and defect engineering. The coexistence of multivalence Cu ions and oxygen vacancies is important to multiferroic behaviors in ZnO:Cu. The samples show clear ferroelectric and ferromagnetic domain patterns. These domain structures may be written reversibly via electric and magnetic bias.

Herng, T.S.; Sanchez-Hanke, C.; Wong, M.F.; Qi, D.; Yi, J.; Kumar, A.; Huang, A.; Kartawidjaja, F.C.; Smadici, S.; Abbamonte, P.; Shannigraphi, S.; Xue, J.M.; Wang, J.; Feng, Y.P.; Rusydi, A.; Zeng, K.; Ding, J.

2011-01-01

307

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)

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.

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

2013-08-01

308

Polarization and interface charge coupling in ferroelectric/AlGaN/GaN heterostructure  

NASA Astrophysics Data System (ADS)

Asymmetrical shift behaviors of capacitance-voltage (C-V) curve with opposite direction are observed in two AlGaN/GaN metal-ferroelectric-semiconductor (MFS) heterostructures with Pb(Zr,Ti)O3 and LiNbO3 gate dielectrics. By incorporating the switchable polar nature of the ferroelectric into a self-consistent calculation, the coupling effect between the ferroelectric and the interface charges is disclosed. The opposite initial orientation of ferroelectric dipoles determined by the interface charges is essentially responsible for the different C-V characteristics. A critical fixed charge density of -1.27 × 1013 cm-2 is obtained, which plays a key role in the dependence of the C-V characteristic on the ferroelectric polarization. The results pave the way for design of memory devices based on MFS structure with heteropolar interface.

Zhang, Min; Kong, Yuechan; Zhou, Jianjun; Xue, Fangshi; Li, Liang; Jiang, Wenhai; Hao, Lanzhong; Luo, Wenbo; Zeng, Huizhong

2012-03-01

309

Ferroelectric optical image comparator  

DOEpatents

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.

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

1993-01-01

310

Ferroelectric\\/superconductor heterostructures  

Microsoft Academic Search

This review covers the fabrication and characterization of ferroelectric\\/superconductor heterostructures such as Pb(ZrxTi1?x)O3\\/YBa2Cu3O7?? (YBCO), BaTiO3\\/YBCO and BaxSr1?xTiO3\\/YBCO etc. on various single crystal substrates. Pulsed laser deposition, laser molecular beam epitaxy, and magnetron-sputtering methods are compared. This report shows that pulsed laser deposition equipped with in situ reflection high-energy electron diffraction is a good method to control the growth mode of

Lin Li

2000-01-01

311

Ferroelectric optical image comparator  

DOEpatents

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. 7 figures.

Butler, M.A.; Land, C.E.; Martin, S.J.; Pfeifer, K.B.

1993-11-30

312

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

SciTech Connect

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.

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

313

Annular electron beam generation using a ferroelectric cathode  

SciTech Connect

In this paper, the authors report on the emission of electrons from a ferroelectric cathode in a coaxial gun geometry. The electrons are emitted from the inner conductor of the coaxial system and are accelerated radially. An axial magnetic field causes the formation of an azimuthal annular electron flow. The electrostatic potential distribution then leads to the ejection of the annular beam from the anode-cathode region into the drift space. A beam energy of up to 50 keV and an electron current of up to 250 A is typical in this proof of principle experiment. The Hull cutoff condition is found to considerably underestimate the magnetic field required to insulate the radial electron current flow in the diode. The results obtained are consistent with earlier data showing that the behavior of the ferroelectric is closely coupled to the changing state of the ferroelectric.

Golkowski, C.; Flechtner, D.; Ivers, J.D.; Nation, J.A.; Schaechter, L. [Cornell Univ., Ithaca, NY (United States)] [Cornell Univ., Ithaca, NY (United States)

1998-06-01

314

Ferroelectricity in one unit-cell period oxide superlattices  

NASA Astrophysics Data System (ADS)

We present electric properties of one unit-cell period superlattices composed of CaTiO3 (CTO), SrTiO3 (STO), and BaTiO3 (BTO) perovskites, in which the structural symmetry and lattice misfit strain can be systematically varied without changing the chemical valence states. The one unit-cell period CTO/BTO, BTO/STO, and CTO/STO superlattices were grown by high oxygen pressure pulsed laser deposition on atomically flat SrRuO3 conducting oxide grown on STO (001) substrates. CTO/BTO and BTO/STO showed ferroelectricity in room temperature, while CTO/STO showed paraelectric behavior. Such spontaneous electric polarization was an unexpected result, because all TiO6 octahedron was not in the same structural condition with ferroelectric BTO, but was sandwiched by CaO (SrO) and BaO layers in these superlattices. By performing first principle calculations, ferroelectric ground states can be found in the distorted TiO6. Moreover, the ferroelectricity was described as the collective displacement of the titanium-oxygen-titanium ions, which is different from that of bulk ferroelectric material.

Noh, T. W.; Lee, J. H.; Lee, H. N.

2005-03-01

315

Multigap Semiconducting ferroelectric perovskites  

NASA Astrophysics Data System (ADS)

The energy conversion efficiency of a solar cell is directly related to the band gap of the material. By doping ferroelectric perovskites with Bi^5+ on the B-site, we propose low band-gap materials suitable for bulk photovoltaic effect and related solar applications.Our DFT calculations indicate that the low-lying 6s empty states of the electronegative Bi atom produce empty isolated bands in the gap of the parent materials, effectively lowering the band gap by 1˜2eV in various perovskites. Ferroelectricity (and therefore inversion symmetry breaking) weakens but survives upon doping, which enables the ``shift current'' mechanism for photocurrent generation, while the decreased band gap helps absorb low energy photons in the visible range. Furthermore, the existence of multiple band gaps allows for solar conversion devices with efficiency beyond the traditional Shockly-Queisser limit, in which successive photon excitations result in carriers with higher energy than a single-step excitation would achieve.

Jiang, Lai; Grinberg, Ilya; Wang, Fenggong; Davies, Peter; Rappe, Andrew

2013-03-01

316

Thin film ferroelectrics: breakthrough  

NASA Astrophysics Data System (ADS)

Now that commercial infrared is a well-established business with several serious competitors, the pressures for a competitive edge have increased dramatically. Hybrid barium strontium titanate (BST) ferroelectric detectors still provide the basis for the majority of systems being produced today, and tens of thousands of systems have been fielded. The system simplicity of these AC-coupled systems is not matchable by any other current technology, but the complexity of the detector fabrication process limits its potential for further substantial cost and performance improvements. DC-coupled VOx bolometers, currently the most popular technology among manufacturers, offer better sensitivity at somewhat greater cost. Although this technology has been heralded as the technology of the future, it is encumbered by a more complicated system architecture and by spatial noise, which limits the ability to take advantage of its greater sensitivity. Thin-film ferroelectric (TFFE) detectors promise to remove the cost and performance barriers that lie ahead of BST technology, while maintaining the low system cost and low spatial noise characteristic of AC-coupled systems. Until recently the promise has been elusive, but now real-world performance of the best of TFFE systems is competitive with the best of any other technology.

Hanson, Charles M.; Beratan, Howard R.

2002-08-01

317

Ferroelectric Thin Films for Electronic Applications  

NASA Astrophysics Data System (ADS)

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.

Udayakumar, K. R.

318

Ferroelectric domain structure of anisotropically strained NaNbO3 epitaxial thin films  

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

319

Ferroelectric behaviour of PZT thin films with secondary TiO2 phase induced defects  

NASA Astrophysics Data System (ADS)

The dielectric properties and ferroelectric phase transition in tetragonal lead zirconate titanate (PZT) thin films containing titanium oxide (TiO2) as a secondary phase have been studied. TiO2 phase inclusion is observed in PZT films prepared by the electron beam evaporation of multicomponent oxides as the result of the dissociation of the pyrochlore PbTi3O7 phase on high-temperature annealing. TiO2 phase inclusion results in the asymmetry of the dielectric hysteresis along the polarization axis. Micro polar regions due to defects caused by TiO2 are responsible for the latter. These regions become randomized due to thermal energy and, as a result, the dielectric hysteresis becomes symmetrical. Investigation of the complex permittivity reveals that the relaxation time decreases with an increase of temperature and, as a result, non-Debye-like behaviour at low temperature gives way to Debye-like behaviour suggesting that the material comprises a large number of relaxing regions. Measurement of the dielectric constant revealed that the ferroelectric-paraelectric phase transition is diffused and shifts to the high-temperature side with a measurement frequency characteristic of the relaxor-like behaviour. This transition follows the quadratic (T-T0)2 law instead of the Curie-Weiss law for normal PZT films. A value of 48 °C was obtained for the diffuseness of the phase transition.

Darvish, S. R.; Rastogi, A. C.

2000-09-01

320

Lead-free and lead-based ABO3 perovskite relaxors with mixed-valence A-site and B-site disorder: Comparative neutron scattering structural study of (Na1/2Bi1/2)TiO3 and Pb(Mg1/3Nb2/3)O3  

NASA Astrophysics Data System (ADS)

We report the results of neutron elastic-scattering measurements made between -250 °C and 620 °C on the lead-free relaxor (Na1/2Bi1/2)TiO3 (NBT). Strong, anisotropic, elastic diffuse scattering intensity decorates the (100), (110), (111), (200), (210), and (220) Bragg peaks at room temperature. The wave-vector dependence of this diffuse scattering is compared to that in the lead-based relaxor Pb(Mg1/3Nb2/3)O3 (PMN) to determine if any features might be common to relaxors. Prominent ridges in the elastic diffuse scattering intensity contours that extend along ?110? are seen that exhibit the same zone dependence as those observed in PMN and other lead-based relaxors. These ridges disappear gradually on heating above the cubic-to-tetragonal phase transition temperature TCT = 523 °C, which is also near the temperature at which the dielectric permittivity begins to deviate from Curie-Weiss behavior. We thus identify the ?110?-oriented ridges as a relaxor-specific property. The diffuse scattering contours also display narrower ridges oriented along ?100? that are consistent with the x-ray results of Kreisel [Phys. Rev. BPRBMDO1098-012110.1103/PhysRevB.68.014113 68, 014113 (2003)]; these vanish near 320 °C, indicating that they have a different physical origin. The ?100?-oriented ridges are not observed in PMN. We observe no equivalent relaxor-specific elastic diffuse scattering from the homovalent relaxor analogues K0.95Li0.05TiO3 (A-site disordered) and KTa0.95Nb0.05O3 (B-site disordered). This suggests that the ?110?-oriented diffuse scattering ridges are correlated with the presence of strong random electric fields and invites a reassessment of what defines the relaxor phase. We find that doping NBT with 5.6% BaTiO3, a composition close to the morphotropic phase boundary with enhanced piezoelectric properties, increases the room-temperature correlation length along [11¯0] from 40 to 60 Å while doubling the associated integrated diffuse scattering. Similar behavior was reported by Matsuura [Phys. Rev. BPRBMDO1098-012110.1103/PhysRevB.74.144107 74, 144107 (2006)] for morphotropic compositions of PMN doped with PbTiO3. Finally, we comment on the recent observation of monoclinicity in NBT at room temperature by placing a strict bound on the strength of the (½½½) superlattice reflection associated with the Cc space group based on the atomic coordinates published in the x-ray study by Aksel [Appl. Phys. Lett.APPLAB0003-695110.1063/1.3573826 98, 152901 (2011)] for NBT. We show that a skin effect, analogous to that reported in the relaxors PZN-xPT and PMN-xPT, can reconcile our neutron single-crystal data with the x-ray powder data of Aksel [Appl. Phys. Lett.APPLAB0003-695110.1063/1.3573826 98, 152901 (2011)]. Our finding of a skin effect in a lead-free, A-site disordered, heterovalent relaxor supports the idea that it arises in the presence of strong random electric fields.

Ge, Wenwei; Devreugd, Christopher P.; Phelan, D.; Zhang, Qinhui; Ahart, Muhtar; Li, Jiefang; Luo, Haosu; Boatner, Lynn A.; Viehland, Dwight; Gehring, Peter M.

2013-11-01

321

Ferroelectric polarization in the magnetic world  

NASA Astrophysics Data System (ADS)

Switchable spontaneous polarization in ferroelectrics is produced by a structural distortion of a high-symmetry reference phase which lowers the symmetry to a polar space group. Under certain conditions, this structural distortion and symmetry breaking can also induce ferromagnetism and other changes, such as a metal-insulator transition, allowing the possibility of electric and magnetic field control. In this talk, I will present first-principles illustrations of specific materials realizations of the rich variety of this behavior in magnetic perovskite oxides, identified using a database of first-principles calculations of the full phonon dispersions of a range of magnetic perovskites, including the d3 compounds SrMnO3and SrCaO3, the d5 compounds BiFeO3, and the series SrMO3 (M= V, Cr, Mn, Fe, Co). First, I will discuss an epitaxial-strain-induced multiferroic phase produced by large spin-phonon coupling in SrMnO3 [1]. Then, I will turn to colossal magnetoresistance based on a ferromagnetic- metal/antiferromagnetic-ferroelectric phase boundary with epitaxial strain in SrCoO3, which exhibits typical ferromagnetic metallic character in room-temperature but with a large spin-phonon coupling by which antiferromagnetic ordering favors a polar distortion. Lastly, I will discuss the identification of perovskite superlattice systems in which the symmetry lowering produced layer-by-layer ordering produces a phase with ferroelectrically-induced weak ferromagnetism. I will present first-principles calculations demonstrating these behaviors in BaMnO3/SrMnO3 superlattices and other systems which could provide robust experimental realizations. [4pt] [1] J. H. Lee and K. M. Rabe, "Epitaxial-strain-induced multiferroicity in SrMnO3 from first principles," Phys. Rev. Lett. 104, 207204 (2010)

Lee, Jun Hee

2011-03-01

322

Structural Consequences of Ferroelectric Nanolithography.  

National Technical Information Service (NTIS)

Domains of remnant polarization can be written into ferroelectrics with nanoscale precision using scanning probe nanolithography techniques such as piezoresponse force microscopy (PFM). Understanding the structural effects accompanying this process has be...

J. Y. Jo P. Chen R. J. Sichel R. T. Smith S. H. Baek

2011-01-01

323

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

SciTech Connect

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.

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

2000-04-04

324

Polarization dependence of molecular adsorption on ferroelectrics.  

PubMed

The structural details of ferroelectric surfaces influence the effect of ferroelectric polarization on surface chemistry, and it is important to understand and control defect functionality as well as identify adsorption sites in ferroelectric materials. Ferroelectric domain polarization has been found to have a significant effect on surface properties and interactions. Here, both the structure and the presence of local electric fields are examined simultaneously. The surface structure and ferroelectric domain orientation are controlled while molecular adsorption effects are quantified. We use scanning tunneling microscopy (STM) to determine the surface and electronic effects of polarization-gas interactions on a model ferroelectric surface, BaTiO3 (001). PMID:23719697

Kraya, Laura Y; Kraya, Ramsey

2013-04-01

326

Ferroelectric infrared detector and method  

DOEpatents

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.

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

2010-03-30

327

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

SciTech Connect

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.

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

1999-06-30

328

Coupled ferromagnetism and ferroelectricity in superlattices of non-ferroelectric antiferromagnetic manganites  

NASA Astrophysics Data System (ADS)

Complex oxide heterostructures present a promising avenue for the design of multifunctional properties which may find application in a variety of technological systems. In heterostructures composed of transition metal oxides the disruption introduced by an interface can affect the balance of the competing interactions among spins, charges and orbitals. This has led to the emergence of properties absent in the original building blocks of a heterostructure. We will report on the discovery of magnetically tunable ferroelectricity in artificial tri-layer superlattices consisting of non-ferroelectric and non-ferromagnetic components: NdMnO3/SrMnO3/LaMnO3.[1] Ferroelectricity was observed below 40 K exhibiting strong tunability by superlattice periodicity. Furthermore, magnetoelectric coupling resulted in 150% magnetic modulation of the polarization. First-principles calculations indicate that broken space inversion symmetry and mixed valency give rise to the observed behavior. This discovery highlights the importance of tri-layered systems for the engineering of emergent properties in oxide heterostructures. [1] K. Rogdakis et al, Nat Commun 3, 1064 (2012)

Burton, J. D.; Rogdakis, K.; Seo, J. W.; Viskadourakis, Z.; Wang, Y.; Qune, L. Ah; Choi, E.; Tsymbal, E.; Lee, J.; Panagopoulos, C.

2013-03-01

329

Harvesting single ferroelectric domain stressed nanoparticles for optical and ferroic applications  

NASA Astrophysics Data System (ADS)

We describe techniques to selectively harvest single ferroelectric domain nanoparticles of BaTiO3 as small as 9 nm from a plethora of nanoparticles produced by mechanical grinding. High resolution transmission electron microscopy imaging shows the unidomain atomic structure of the nanoparticles and reveals compressive and tensile surface strains which are attributed to the preservation of ferroelectric behavior in these particles. We demonstrate the positive benefits of using harvested nanoparticles in disparate liquid crystal systems.

Cook, G.; Barnes, J. L.; Basun, S. A.; Evans, D. R.; Ziolo, R. F.; Ponce, A.; Reshetnyak, V. Yu.; Glushchenko, A.; Banerjee, P. P.

2010-09-01

330

Ferroelectric Instability Under Screened Coulomb Interactions  

NASA Astrophysics Data System (ADS)

We explore the effect of charge carrier doping on ferroelectricity using density functional calculations and phenomenological modeling. By considering a prototypical ferroelectric material, BaTiO3, we demonstrate that ferroelectric displacements are sustained up to the critical concentration of 0.11 electron per unit cell volume. This result is consistent with experimental observations and reveals that the ferroelectric phase and conductivity can coexist. Our investigations show that the ferroelectric instability requires only a short-range portion of the Coulomb force with an interaction range of the order of the lattice constant. These results provide a new insight into the origin of ferroelectricity in displacive ferroelectrics and open opportunities for using doped ferroelectrics in novel electronic devices.

Wang, Yong; Liu, Xiaohui; Burton, J. D.; Jaswal, Sitaram S.; Tsymbal, Evgeny Y.

2012-12-01

331

Multiaxial models and experiments with ferroelectrics  

NASA Astrophysics Data System (ADS)

The use of ferroelectrics in increasingly demanding roles as sensors and actuators motivates study of their fundamental constitutive behavior. This paper gives a preliminary report on measurements of the behavior of PZT-5H under multiaxial loading paths, and comparison with model predictions. The loading paths considered are loading of poled material with electric field at various angles (theta) to the poling direction, and loading with uniaxial compressive stress rotated through various angles (theta) to the poling direction. In each case the material response is measured by tracking electric displacement in the form of surface charge. Model predictions are made using a self-consistent crystal plasticity approach. The model is able to predict well the response to multiaxial electric field loading. There is good qualitative agreement in the case of mechanical loading.

Huber, John E.; Fleck, Norman A.

2000-06-01

332

Influence of step heights and terrace lengths of bottom electrodes on structural and ferroelectric properties of BiFeO3 thin films  

Microsoft Academic Search

The ferroelastic domain structures of epitaxial ferroelectric thin films are critical to control the ferroelectric properties. We have already demonstrated the selection of ferroelastic domain structure variants in epitaxial BiFeO3 films and consequently significant improvement in ferroelectric switching behavior and leakage current by employing miscut in cubic (001) SrTiO3 substrates. We have also observed significant step bunching in the SrRuO3

Jae-Wan Park; Seung-Hyub Baek; Chang-Beom Eom

2009-01-01

333

Nnn-Ising Model Simulation of Nanodomain Textures in Relaxor-Type Lead Scandium Tantalate  

NASA Astrophysics Data System (ADS)

Chemical domain textures for lead scandium tantalate (PST) are modelled using Monte Carlo (MCS) and next-nearest-neighbor Ising (NNNI) models. A wide range of degrees of short- and long-range ordering of the (Ta, Sc) atoms occur in ceramic specimens, depending on processing routes. The simulations help us understand and quantify the chemical domain textures, chemical domain wall configurations and other chemical defects which may occur in certain relaxor-type perovskite-type oxides. The results are compared to dark-field transmission electron microscopic observations. Some new types of small defects were discovered. These are described and classified. The results provide a first step towards the development of a microscopic statistical physics framework for analytical theories of the dielectric response of relaxor-type ceramics, where the frequency and temperature variation of the permittivity are due essentially to dipolar-type fluctuations on nanometer scales.

Qian, H.; Peng, J. L.; Bursill, L. A.

334

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

NASA Astrophysics Data System (ADS)

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.

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

335

Inorganic ceramic\\/polymer ferroelectric composite electrets  

Microsoft Academic Search

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

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

1996-01-01

336

Etching Behavior and Damage Rejuvenation of Top Electrode and Bi3.15Nd0.85Ti3O12 Films Applied in Ferroelectric Random Access Memory Devices  

NASA Astrophysics Data System (ADS)

Reactive ion etching (RIE) and ion beam etching (IBE) were used to etch the Bi3.15Nd0.85Ti3O12 (BNdT) ferroelectric layer and top electrode (TE), respectively, for ferroelectric random access memory (FeRAM) applications. The effect of dry etching on the ferroelectric properties of Pt/BNdT/Pt capacitors and the film etching mechanism were investigated. After TE etching, the remanent polarization (2Pr) of capacitors decreased through the charging effect, but was recovered by rapid thermal annealing (RTA). A distinct polarization suppression of the capacitors was observed after BNdT layer dry etching owing to the large amount of ions accumulated in the electrode/film interface and within the films. The property damage could be recovered after long-time furnace annealing. The capacitor property rejuvenation was complete even after 1010 switching cycles of fatigue test. The capacitor size effect and recovery of the ferroelectric properties after film etching process were also studied.

Xie, Dan; Yu, Wenkao; Luo, Yafeng; Xue, Kanhao; Ren, Tianling; Liu, Litian

2009-05-01

337

Recent Development in Polymer Ferroelectric Field Effect Transistor Memory  

Microsoft Academic Search

The article presents the recent research development in polymer ferroelectric non-volatile memory. A brief overview is given of the history of ferroelectric memory and device architectures based on inorganic ferroelectric materials. Particular emphasis is made on device elements such as metal\\/ferroelectric\\/metal type capacitor, metal- ferroelectric-insulator-semiconductor (MFIS) and ferroelectric field effect transistor (FeFET) with ferroelectric poly(vinylidene fluoride) (PVDF) and its copolymers

Youn Jung Park; Hee June Jeong; Jiyoun Chang; Seok Ju Kang

2008-01-01

338

Relaxor-PbTiO3 Single Crystals for Various Applications  

PubMed Central

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.

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

2014-01-01

339

Relaxor-PbTiO(3) single crystals for various applications.  

PubMed

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

Shujun Zhang; Fei Li; Jun Luo; Sahul, R; Shrout, T R

2013-08-01

340

Chemical order in PMN-related relaxors: structure, stability, modification, and impact on properties  

Microsoft Academic Search

High temperature thermal treatments were used to modify the cation order in several tantalate and niobate members of the Pb(Mg1\\/3Nb2\\/3)O3 (PMN) family of relaxors. The observation of complete 1:1 structural order in several compositions, and the refined cation occupancies of well-ordered samples conflict with the predictions of the “space charge” model, and support the “random site” description for the B-site

P. K Davies; M. A Akbas

2000-01-01

341

Emission from ferroelectric cathodes  

SciTech Connect

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.

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

1993-05-17

342

Emission from ferroelectric cathodes  

NASA Astrophysics Data System (ADS)

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.

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

1993-05-01

343

Emission from ferroelectric cathodes  

NASA Astrophysics Data System (ADS)

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.

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

1994-02-01

344

Polarization-modulated rectification at ferroelectric surfaces.  

PubMed

By correlating room temperature conductive atomic force microscopy with low temperature electrostatic force microscopy images of the same sample region, we demonstrate that nanoscale electric conduction between a sharp tip and the surface of ferroelectric HoMnO3 is intrinsically modulated by the polarization of ferroelectric domains. Conductance spectra reveal that the electric conduction is described by polarization-induced Schottky-like rectification at low bias, but dominated by a space-charge limited conduction mechanism at high bias. Our observation demonstrates visualization of ferroelectric domain structure by electric conduction, which may be used for nondestructive readout of nanoscale ferroelectric memories and/or ferroelectric sensors. PMID:20867135

Wu, Weida; Guest, J R; Horibe, Y; Park, S; Choi, T; Cheong, S-W; Bode, M

2010-05-28

345

Ferroelectric memory based on nanostructures  

PubMed Central

In the past decades, ferroelectric materials have attracted wide attention due to their applications in nonvolatile memory devices (NVMDs) rendered by the electrically switchable spontaneous polarizations. Furthermore, the combination of ferroelectric and nanomaterials opens a new route to fabricating a nanoscale memory device with ultrahigh memory integration, which greatly eases the ever increasing scaling and economic challenges encountered in the traditional semiconductor industry. In this review, we summarize the recent development of the nonvolatile ferroelectric field effect transistor (FeFET) memory devices based on nanostructures. The operating principles of FeFET are introduced first, followed by the discussion of the real FeFET memory nanodevices based on oxide nanowires, nanoparticles, semiconductor nanotetrapods, carbon nanotubes, and graphene. Finally, we present the opportunities and challenges in nanomemory devices and our views on the future prospects of NVMDs.

2012-01-01

346

Nanoscale ferroelectric tunnel junctions based on ultrathin BaTiO3 film and Ag nanoelectrodes  

NASA Astrophysics Data System (ADS)

In this work, Ag nanoisland electrodes (nanoelectrodes) have been deposited on top of ultrathin ferroelectric BaTiO3 (BTO) films to form a nanoscale metal-ferroelectric-metal tunnel junction by integrating growth techniques of nanocluster beam source and laser-molecular beam epitaxy. The ultrathin BTO films (~3 nm thick) exhibit both apparent ferroelectric polarization reversal and ferroelectric tunneling related resistive switching behaviors. The introducing of Ag nanoislands (~20 nm in diameter) as top electrode substantially enhances the tunneling current and alters the symmetry of I-V hysteresis curves. The enhanced tunneling current is likely due to the reduction in tunneling barrier height and an increase in effective tunneling area by Ag nano-electrodes, while the improved symmetric in I-V curve may be attributed to the variation of electrode-oxide contact geometry.

Gao, X. S.; Liu, J. M.; Au, K.; Dai, J. Y.

2012-10-01

347

Compact modelling of ferroelectric tunnel memristor and its use for neuromorphic simulation  

NASA Astrophysics Data System (ADS)

Ferroelectric tunnel memristor (FTM) was recently discovered. Its resistance can be continuously tuned by controlling the growth of domain in ferroelectric tunnel barrier. Experiments show its large OFF/ON resistance ratio (>102) and high operation speed (˜10 ns), providing great potential to build up multi-level storage and neuromorphic circuits. However, the corresponding electrical model for circuit simulation is still lacking. In this Letter, we developed a compact model for a voltage-controlled ferroelectric tunnel memristor based on experimental results and ferroelectric switching dynamics. The memristive behavior of this model was demonstrated by resistance measurements as a function of the amplitude and duration of programming voltage pulses, and the accuracy was validated by the relative good agreement between simulation results and experimental measurement. Our model was used to simulate a FTM-based spike-timing dependent plasticity circuit to show its use in neuromorphic circuits.

Wang, Zhaohao; Zhao, Weisheng; Kang, Wang; Zhang, Yue; Klein, Jacques-Olivier; Ravelosona, Dafiné; Chappert, Claude

2014-02-01

348

Defect-mediated polarization switching in ferroelectrics and related materials: from mesoscopic mechanisms to atomistic control  

SciTech Connect

The plethora of lattice and electronic behaviors in ferroelectric and multiferroic materials and heterostructures opens vistas into novel physical phenomena including magnetoelectric coupling and ferroelectric tunneling. The development of new classes of electronic, energy-storage, and information-technology devices depends critically on understanding and controlling field-induced polarization switching. Polarization reversal is controlled by defects that determine activation energy, critical switching bias, and the selection between thermodynamically equivalent polarization states in multiaxial ferroelectrics. Understanding and controlling defect functionality in ferroelectric materials is as critical to the future of oxide electronics and solid-state electrochemistry as defects in semiconductors are for semiconductor electronics. Here, recent advances in understanding the defect-mediated switching mechanisms, enabled by recent advances in electron and scanning probe microscopy, are discussed. The synergy between local probes and structural methods offers a pathway to decipher deterministic polarization switching mechanisms on the level of a single atomically defined defect.

Kalinin, Sergei V [ORNL; Rodriguez, Brian J [ORNL; Baddorf, Arthur P [ORNL; Balke, Nina [ORNL; Borisevich, Albina Y [ORNL; Chang, Hye Jung [ORNL; Chen, Long-Qing [Pennsylvania State University; Jesse, Stephen [ORNL; Maksymovych, Petro [ORNL; Nikiforov, Maxim [ORNL; Pennycook, Stephen J [ORNL

2010-01-01

349

Tuning the ferroelectric polarization in a multiferroic metal-organic framework.  

PubMed

We perform density functional theory calculations on a recently synthesized metal-organic framework (MOF) with a perovskite-like topology ABX3, i.e., [CH3CH2NH3]Mn(HCOO)3, and predict a multiferroic behavior, i.e., a coexistence of ferroelectricity and ferromagnetism. A peculiar canted ordering of the organic A-cation dipole moments gives rise to a ferroelectric polarization of ~2 ?C/cm(2). Starting from these findings, we show that by choosing different organic A cations, it is possible to tune the ferroelectric polarization and increase it up to 6 ?C/cm(2). The possibility of changing the magnitude and/or the canting of the organic molecular dipole opens new routes toward engineering ferroelectric polarization in the new class of multiferroic metal-organic frameworks. PMID:24191632

Di Sante, Domenico; Stroppa, Alessandro; Jain, Prashant; Picozzi, Silvia

2013-12-01

350

Chemical Solution Depositionof Layer-Structured Ferroelectric Thin Films  

Microsoft Academic Search

Ferroelectric rare-earth-doped Bi 4Ti 3O 12 thin films have been successfully prepared on Si-based substrates by using metallo-organic precursor solutions. The pyrolysis behavior of (Bi, R) 4Ti 3O 12 precursors depends upon the starting rare earth source, which strongly affects the surface morphology of the synthesized film. Among the (Bi, R) 4Ti 3O 12 films, BNT thin films reveal the

Shin-ichi Hirano; Takashi Hayashi; Wataru Sakamoto; Koichi Kikuta; Toshinobu Yogo

351

Effects of frequency and temperature evolution of polar nanoregions on susceptibility dispersion and polarization mechanism in relaxors  

NASA Astrophysics Data System (ADS)

A generic theory for the frequency and temperature effects on the characteristic evolution of polar nanoregions (PNRs) is essential for improving and optimizing the design of relaxor-based piezoelectric and electrocaloric cooling devices. Pauli's master equation was used to deduce analytical expressions for both the polarization dynamics and frequency-tunable susceptibility dispersions of relaxors. This was done by coupling the intrinsic equilibrium and dynamic factors of bulk relaxors and thin-films. It has been found that for relaxors to comply with Vogel-Fulcher relation, the evolution of PNR mean volume and coercive field of localized electric hysteresis for PNRs has to obey the classic Merz's switching law. The evolution of PNR mean volume in Pb(Mg1/3Nb2/3)O3 crystal was calculated in the temperature range of 200-300 K and at different frequencies up to 1012 Hz. Our results were in good agreement with the mean-field percolation theory and experimental correlation lengths. Hence, the proposed theory may serve as a new basis for studying the relationship between macroscopic dielectric, electrocaloric as well as other important properties of relaxors and evolutions of their typical microstructures.

Shi, Y. P.; Soh, A. K.

2011-12-01

352

Ferroelectric, dielectric and piezoelectric properties of ferroelectric thin films and ceramics  

NASA Astrophysics Data System (ADS)

Ferroelectric, dielectric and piezoelectric properties of ferroelectric thin films and ceramics are reviewed with the aim of providing an insight into different processes which may affect the behaviour of ferroelectric devices, such as ferroelectric memories and micro-electro-mechanical systems. Taking into consideration recent advances in this field, topics such as polarization switching, polarization fatigue, effects of defects, depletion layers, and depolarization fields on hysteresis loop behaviour, and contributions of domain-wall displacement to dielectric and piezoelectric properties are discussed. An introduction into dielectric, pyroelectric, piezoelectric and elastic properties of ferroelectric materials, symmetry considerations, coupling of electro-mechanical and thermal properties, and definitions of relevant ferroelectric phenomena are provided.

Damjanovic, Dragan

1998-09-01

353

Controlling structure distortions in 3-layer ferroelectric Aurivillius oxides  

SciTech Connect

Combined Rietveld refinements of x-ray and neutron powder diffraction data were used to understand the subtle structure distortions in 3-layer Aurivillius oxides that yield off-centering displacements in ferroelectric and multiferroic compositions. Ferroelectric phases including Bi{sub 2}A{sub 2}Ti{sub 3}O{sub 12} (A=La, Pr, Nd, La/Pr, La/Nd, Pr/Nd), Bi{sub 2}A{sub 2}TiNb{sub 2}O{sub 12} (A=Ca/Sr, Sr, and Sr/Ba) and Bi{sub 2}A{sub 2}TiTa{sub 2}O{sub 12} (A=Ca/Sr, and Sr/Ba) were studied to separate the effects of cation size and charge on the structure distortions and properties. A new approach to describing the local coordination around the Ti, Nb, and/or Ta ions is presented, where the oxygen octahedra are characterized as containing kinks in three dimensions. The kink angles follow trends with the A-site ionic radius and the ferroelectric polarization. The driving force for extensive cation site mixing between the Bi and A-site cations has been clearly established, with site mixing required to maintain interlayer bonding. - Graphical abstract: Distortion of the oxygen octahedra from planar geometries can be controlled via choice of the perovskite A-site cation, and the kink angle correlates with cation off-centering and ferroelectric polarization. Highlights: Black-Right-Pointing-Pointer A-site cations define the tilt and distortion of the octahedral. Black-Right-Pointing-Pointer Distortions of oxygen octahedra, ignoring the central cation, link to ferroelectric polarization. Black-Right-Pointing-Pointer Bi ion occupancy in the perovskite causes distortion of the oxygen sublattice. Black-Right-Pointing-Pointer We predict multiferroic behavior from off-centering caused by the Bi ion lone pair.

Nichols, Eric J.; Shi, Jiawanjun [Kazuo Inamori School of Engineering, Alfred University, Alfred, NY 14802 (United States); Huq, Ashfia [Neutron Scattering Science Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Vogel, Sven C. [Manuel Lujan Jr. Neutron Scattering Center, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Misture, Scott T., E-mail: misture@alfred.edu [Kazuo Inamori School of Engineering, Alfred University, Alfred, NY 14802 (United States)

2013-01-15

354

Energy principle of ferroelectric ceramics and single domain mechanical model  

NASA Astrophysics Data System (ADS)

Many physical experiments have shown that the domain switching in a ferroelectric material is a complicated evolution process of the domain wall with the variation of stress and electric field. According to this mechanism, the volume fraction of the domain switching is introduced in the constitutive law of ferroelectric ceramic and used to study the nonlinear constitutive behavior of ferroelectric body in this paper. The principle of stationary total energy is put forward in which the basic unknown quantities are the displacement u i , electric displacement D i and volume fraction ? I of the domain switching for the variant I. Mechanical field equation and a new domain switching criterion are obtained from the principle of stationary total energy. The domain switching criterion proposed in this paper is an expansion and development of the energy criterion. On the basis of the domain switching criterion, a set of linear algebraic equations for the volume fraction ? I of domain switching is obtained, in which the coefficients of the linear algebraic equations only contain the unknown strain and electric fields. Then a single domain mechanical model is proposed in this paper. The poled ferroelectric specimen is considered as a transversely isotropic single domain. By using the partial experimental results, the hardening relation between the driving force of domain switching and the volume fraction of domain switching can be calibrated. Then the electromechanical response can be calculated on the basis of the calibrated hardening relation. The results involve the electric butterfly shaped curves of axial strain versus axial electric field, the hysteresis loops of electric displacement versus electric filed and the evolution process of the domain switching in the ferroelectric specimens under uniaxial coupled stress and electric field loading. The present theoretic prediction agrees reasonably with the experimental results given by Lynch.

Liu, Feng; Li, Haijun; Wang, T. C.

2007-10-01

355

Ferroelectric magnets: a Conical Spiral and an Ising Chain  

NASA Astrophysics Data System (ADS)

Multiferroics, where magnetic order with broken inversion symmetry accompanies the occurrence of ferroelectric polarization, can show remarkable tunability of dielectric properties by applied magnetic fields, such as reversibly flipping of ferroelectric polarization or a drastic change of dielectric constant with fields. It turns out that the origin of ferroelectricity in most of new multiferroics is spiral magnetism that tends to produce uniform lattice distortions, i.e., ferroelectric distortions, through antisymmetric exchange coupling. Among such materials, spinel CoCr2O4, exhibiting a conical-spiral spin order, is unique in that it exhibits spontaneous magnetization as well as electric polarization. We have studied the detailed switching behavior of magnetoelectric domains, characterized by polarization, magnetization, and magnetic wave vector, under variation of temperature and applied magnetic fields. New aspects that we have discovered from this study include [1] polarization reversal at the magnetic lock-in transition temperature (TL) with thermal variation or with isothermal variation of magnetic fields (without changing their direction) at a temperature near TL, [2] surprisingly, this polarization reversal happens without change in spin rotation direction in spiral spins. We also present newly-discovered multiferroicity in a ``collinear'' chain magnet of Ca3(Co,Mn)2O6. In the Ising chain magnet, ``symmetric'' exchange coupling seems responsible for the multiferroicity. We show that in Ca3Co2-xMnxO6 (x 1), the ferroelectricity originates from the coexistence of the alternating order of magnetic ions with different charges and the collinear up-up-down-down spin order in the frustrated spin chain. The system also exhibits magnetic freezing transitions that affect the temperature dependence of the electric polarization magnitude.

Choi, Young Jai

2009-03-01

356

Nonlinear microwave properties of ferroelectric thin films  

NASA Astrophysics Data System (ADS)

The nonlinear microwave properties of ferroelectric SrTiO3 thin films are characterized via complex analysis of the intermodulation distortion (IMD) signals up to high microwave power. The measurements reveal an unusual dependence of the IMD signals on the input power, which indicates the presence of two different nonlinear properties being responsible for the generation of IMD, i.e., the nonlinear permittivity and conductivity at low and high rf power levels, respectively. The IMD signal strength cannot be explained in terms of the classical description based on a Taylor expansion of the nonlinear parameter. In contrast, simulations of the frequency spectra using more appropriate descriptions of two nonlinear parameters yield an excellent agreement between theory and experiment, and, thus, demonstrate that the IMD experiments together with the simulation might provide further insight into the mechanism of nonlinear behavior of these materials.

Ott, R.; Lahl, P.; Wördenweber, R.

2004-05-01

357

Physical Properties of Ferroelectric Mixed Crystals  

NASA Astrophysics Data System (ADS)

The recent studies of the KH2PO4 family mixed crystals with long-range ferroelectric (FE) order and short-range glass order have been reviewed. In mixed crystals of KH2PO4 family FE or antiferroelectric (AFE) with intermediate mixing concentration, a competing interaction gives rise to a nonergodic proton glass (PG) similar to magnetic spin glass. To understand the phase diagram, we have investigated the phase near FE boundary and observed a coexistence of FE and PG in Rb1-x(NH4)xH2AsO4 and Rb1-x(NH4)xH2PO4 mixed crystals. The nonergodic behavior of the coexisting PG was investigated by the polarization as well as dielectric constant measurement. The remaining FE polarization and the low freezing temperature were discussed in terms of mean field model of dipole glass systems.

Kwun, Sook-Il; Noh, Keum Hwan

2001-04-01

358

Strong coupling of ferroelectricity and magnetism in the hexagonal ferrites  

NASA Astrophysics Data System (ADS)

During the last decade one of the most extensively studied class of multiferroics has been the hexagonal rare-earth manganites RMnO3 where R=Dy-Lu, Y, Sc. These compounds exhibit antiferromagnetic (AFM) order with a Néel temperature TN 100 K. In addition, they are improper ferroelectrics (TC> 1200K) driven a by zone-tripling structural distortion associated with a buckling of the R-planes and a rotation of the oxygen trigonal bipyramids. The improper nature of the transition is responsible for the fascinating, topologically protected trimer-domains. Even though magnetism and ferroelectricity in these materials are not intrinsically coupled, there is a non-trivial interaction between the structural and magnetic domain walls. In contrast to the manganites, the ground state structure of the rare-earth ferrites RFeO3 is the orthorhombic perovskite. Recently, however, thin films of RFeO3 have been epitaxially stabilized in the hexagonal rare-earth manganite structure. This development has triggered several new studies of these hexagonal ferrite systems. Similar to manganites, ferrites exhibit ferroelectricity above room temperature and crystallize in P63cm polar structure but conflicting results have been reported as to the origin of ferroelectricity in these materials. Unlike the manganites, recent neutron diffraction measurements suggest a considerably high AFM ordering temperature, TN=440 K. Additionally there is an indication of a second temperature, TwFM˜100K, at which weak ferromagnetism has been observed. In this work my collaborators (Alex Wysocki and Craig J. Fennie) and I address the nature of ferroelectricity and magnetic order in the RFeO3 systems from first-principles. We elucidate the origin of ferroelectricity in the rare-earth ferrites and provide many useful insights into their magnetic behavior, which we will show is fundamentally different than that observed in the manganites. Combining first-principles calculations with a detailed modeling of the magnetic structure we will also show how this difference leads to an interplay between ferroelectricity and magnetism in the ferrites. This strong coupling, absent in the hexagonal manganites, manifests itself in a nontrivial way that may be useful for voltage controlled magnetic functionalities.

Das, Hena

2013-03-01

359

Fatigue effect in bulk ferroelectrics  

Microsoft Academic Search

We have used a kinetic approach to the fatigue phenomenon in ferroelectrics for the analysis of the evolution of switching current and strain hysteresis loops in bulk PZT ceramics and the switching current in PZN-PT single crystals during cyclic switching. It is proposed that fatigue is due to a redistribution of the local internal bias field during cycling (spatially non-uniform

Vladimir Y. Shur; Evgenii L. Rumyantsev; Ekaterina Nikolaeva; Eugene Shishkin; Ivan Baturin; Alevtina Shur; Doru C. Lupascu; Clive A. Randall; Metin Ozgul

2002-01-01

360

Proximity to a ferroelectric instability in Ba1-xCaxZrO3  

NASA Astrophysics Data System (ADS)

Ferroelectricity in ABO3 perovskites driven by A-site disorder is seen as a powerful approach toward lead-free piezoelectrics and ferroelectrics as well as to forming multiferroic compounds. Here we investigate the Ba1-xCaxZrO3 solid solution by structural and dielectric measurements on pulsed laser deposition grown films and by first principles calculations. Films on SrRuO3-coated SrTiO3 substrates are studied for x between 0 and 0.44. Despite the expectation that the Ca-ions assume off-center positions in the perovskite lattice, dielectric measurements show no evidence for ferroelectricity. This behavior is explained by first principles supercell calculations that show ferroelectricity at expanded volume but a rapid suppression thereof as the volume is reduced, thus indicating that our paraelectric Ba1-xCaxZrO3 films are close to a ferroelectric instability. These results demonstrate the important interplay between unit cell volume and ferroelectricity arising from off-centered ions.

Kim, H. S.; Christen, H. M.; Biegalski, M. D.; Singh, D. J.

2010-09-01

361

Supramolecular bola-like ferroelectric: 4-methoxyanilinium tetrafluoroborate-18-crown-6.  

PubMed

Molecular motion is one of the structural foundations for the development of functional molecular materials such as artificial motors and molecular ferroelectrics. Herein, we show that pendulum-like motion of the terminal group of a molecule causes a ferroelectric phase transition. Complex 4-methoxyanilinium tetrafluoroborate-18-crown-6 ([C(7)H(10)NO(18-crown-6)](+)[BF(4)](-), 1) shows a second-order ferroelectric phase transition at 127 K, together with an abrupt dielectric anomaly, Debye-type relaxation behavior, and the symmetry breaking confirmed by temperature dependence of second harmonic generation effect. The origin of the polarization is due to the order-disorder transition of the pendulum-like motions of the terminal para-methyl group of the 4-methoxyanilinium guest cation; that is, the freezing of pendulum motion at low temperature forces significant orientational motions of the guest molecules and thus induces the formation of the ferroelectric phase. The supramolecular bola-like ferroelectric is distinct from the precedent ferroelectrics and will open a new avenue for the design of polar functional materials. PMID:21744841

Fu, Da-Wei; Zhang, Wen; Cai, Hong-Ling; Zhang, Yi; Ge, Jia-Zhen; Xiong, Ren-Gen; Huang, Songping D

2011-08-17

362

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

NASA Astrophysics Data System (ADS)

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.

Ivry, Yachin; Wang, Nan; Durkan, Colm

2014-03-01

363

Ferromagnetism and exchange bias in a diluted magnetic ferroelectric oxide  

NASA Astrophysics Data System (ADS)

We report on the observations of room-temperature ferromagnetism and ferroelectricity in the epitaxial thin film of BaTi0.98Co0.02O3 (CBTO) with detailed structural and magnetic analyses. The films are single phase with an inhomogeneous distribution of Co2+ dopants in the structure. Room-temperature ferromagnetic hysteresis and ferroelectric loop were observed. Remarkably, the hysteresis loops for field cooling show the exchange bias and training effects. The complex magnetic behavior of CBTO was interpreted in the frame of bound magnetic polaron formation with inhomogeneity of dopant distribution. This work also demonstrated that exchange bias can be a helpful technique in exploring the mechanism of dopant-induced ferromagnetism.

Luo, L. B.; Zhao, Y. G.; Tian, H. F.; Yang, J. J.; Li, J. Q.; Ding, J. J.; He, B.; Wei, S. Q.; Gao, C.

2009-03-01

364

Ferroelectric transitions at ferroelectric domain walls found from first principles.  

PubMed

We present a first-principles study of model domain walls (DWs) in prototypic ferroelectric PbTiO_{3}. At high temperature the DW structure is somewhat trivial, with atoms occupying high-symmetry positions. However, upon cooling the DW undergoes a symmetry-breaking transition characterized by a giant dielectric anomaly and the onset of a large and switchable polarization. Our results thus corroborate previous arguments for the occurrence of ferroic orders at structural DWs, providing a detailed atomistic picture of a temperature-driven DW-confined transformation. Beyond its relevance to the field of ferroelectrics, our results highlight the interest of these DWs in the broader areas of low-dimensional physics and phase transitions in strongly fluctuating systems. PMID:24996110

Wojde?, Jacek C; Iñiguez, Jorge

2014-06-20

365

Ferroelectric Transitions at Ferroelectric Domain Walls Found from First Principles  

NASA Astrophysics Data System (ADS)

We present a first-principles study of model domain walls (DWs) in prototypic ferroelectric PbTiO3. At high temperature the DW structure is somewhat trivial, with atoms occupying high-symmetry positions. However, upon cooling the DW undergoes a symmetry-breaking transition characterized by a giant dielectric anomaly and the onset of a large and switchable polarization. Our results thus corroborate previous arguments for the occurrence of ferroic orders at structural DWs, providing a detailed atomistic picture of a temperature-driven DW-confined transformation. Beyond its relevance to the field of ferroelectrics, our results highlight the interest of these DWs in the broader areas of low-dimensional physics and phase transitions in strongly fluctuating systems.

Wojde?, Jacek C.; Íñiguez, Jorge

2014-06-01

366

First-principles investigation of graphene on the ferroelectric LiNbO3(001) surface  

NASA Astrophysics Data System (ADS)

Recent experiments on graphene-ferroelectric field-effect transistors have introduced an excellent nonvolatility functionality. However, the mechanism of the antihysteresis behavior of graphene on some ferroelectric substrates is controversial. We carry out first-principles calculations to study the interface interaction between graphene and the ferroelectric LiNbO3(001) surface, and find that, when putting a bilayer graphene on a clean surface, the spontaneous polarization field can induce a gap of about 311 meV. If the clean surface is passivated with hydrogen, the electrons are trapped at the interface and nearly screen the polarization field. Our results reveal that the antihysteresis behavior originates from the charge trapping which occurs at the hydrogenated graphene-ferroelectric interface.

Ding, Jun; Wen, Li-Wei; Li, Hai-Dong; Kang, Xiu-Bao; Zhang, Jian-Min

2013-10-01

367

Relaxor-like dielectric response of spin liquid CuCrO2  

NASA Astrophysics Data System (ADS)

Broadband dielectric analysis (10-2-107 Hz) of layered triangular lattice CuCrO2 is performed (123 K - 473 K) and analyzed in connection with recently observed spin frustration in this multiferroic [M. Poienar et al. Phys. Rev. B 81, 104411, (2010); M. Frontzek et al. Phys. Rev. B 84, 094448, (2011)]. Most unexpectedly, this well known delafossite has found to have nontrivial charge degrees of freedom, being characterized by a relaxor-like dielectric relaxation around 375 K with FWHM of ˜100K. The result strongly suggests the existence of intermolecular Coulomb interaction between charge disproportionation induced electric dipoles.

Mazumder, N.; Ghorai, U. K.; Roy, R.; Saha, S.; Chattopadhyay, K. K.

2014-04-01

368

Ferroelectric energy generator, system, and method  

US Patent & Trademark Office Database

Embodiments of the present invention provide methods and energy generators that generate electrical energy through direct explosive shock wave depolarization of at least one ferroelectric element. In one embodiment, a generator (10) comprises a ferroelectric element (12), output terminals (14) coupled with the ferroelectric element (12), an explosive charge (16), and a detonator (18) coupled with the explosive charge (16). The detonator (18) is operable to detonate the explosive charge (16) to generate a shock wave that propagates at least partially through the ferroelectric element (12) to generate a voltage across at least two of the output terminals (14).

2009-07-14

369

The study of the ferroelectric phase transition in nanoscale sodium nitrite by the method of thermal noise  

NASA Astrophysics Data System (ADS)

The ferroelectric phase transition for bulk and nanosized sodium nitrite was studied by the thermal noise method. It was shown that the intrinsic noise generated in the samples at frequencies above 10 MHz near the ferroelectric phase transition follows the behavior of the dielectric constant. The noise level in the loaded MCM-41 films with unidirectional pores was approximately twice as large as that for the pressed samples.

Stukova, E. V.; Baryshnikov, S. B.; Shatskaya, Yu. A.; Charnaya, E. V.; Patrushev, Yu. V.

370

Ferroelectric Stirling-Cycle Refrigerator  

NASA Technical Reports Server (NTRS)

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).

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

1999-01-01

371

Size effects in nanostructured ferroelectrics.  

SciTech Connect

The finite size effect in ferroelectrics results in structural instability, imposing a limitation of physical sizes and dimensions of materials in which electric dipoles can be sustained. To evaluate the ultimate limitation of physical sizes for a stable polar phase, the characteristic sizes, i.e., anisotropic correlation lengths of electric dipoles, in a ferroelectric have been examined by considering the surface effect. The size dependence on the Curie temperature in particular is calculated with consideration of crystallographic anisotropy. The mean-field theory shows that the limitation of transverse critical sizes is strongly dependent upon the thickness. In turn, the limitation of the critical thickness is also closely associated with the transverse critical sizes.

Li, S.; Eastman, J. A.; Li, Z.; Foster, C. M.; Newnham, R. E.; Cross, L. E.; Materials Science Division; Pennsylvania State Univ.

1996-01-01

372

Structural, Dielectric, Piezoelectric and Ferroelectric Characterization of NBT-BT Lead-Free Piezoelectric Ceramics  

NASA Astrophysics Data System (ADS)

Lead free piezoelectric 0.94(Na0.5Bi0.5)TiO3-0.06BaTiO3 (NBT-BT) ceramics were synthesized in MPB composition by conventional solid state reaction method. The crystalline nature of NBT-BT ceramic was studied by XRD and the size of the grains are determined by SEM. The X- ray diffraction results reveal that Ba2+ diffuse into the Na0.5 Bi0.5TiO3 lattices to form a solid solution with a pure perovskite structure. Because of the strong ferroelectricity and MPB, the ceramics exhibit high piezoelectric properties: d33 = 206 pC/N. Td (depolarization temperature) and Tm (temperature at with the dielectric constant epsilonr reaches a maximum) were observed through the phase transition in dielectric studies. In addition, the prepared ceramic exhibits relaxor characteristic, which probably results from the cation disordering in the 12fold coordination sites. Pr and Ec of the prepared ceramics were determined from the P-E hysteresis loop.

Shanmuga Sundari, S.; Kumar, Binay; Dhanasekaran, R.

2013-05-01

373

The Hysteretic Ferroelectric Tunnel FET  

Microsoft Academic Search

We present the fabrication and the electrical characterization of ferroelectric tunnel FETs (Fe-TFETs). This novel family of hysteretic switches combines the low subthreshold power of band-to-band tunneling devices with the retention characteristics of Fe gate stacks, offering some interesting features for future one-transistor (1T) memory cells. We report Ion\\/Ioff larger than 105 and Ioff on the order of 100 fA\\/?m

Adrian M. Ionescu; Livio Lattanzio; Giovanni A. Salvatore; L. De Michielis; Kathy Boucart; Didier Bouvet

2010-01-01

374

Artificial Control of Order Degree State of B-Site Ions in Ba(Zr,Ti)O3 by a Superlattice Technique  

NASA Astrophysics Data System (ADS)

Artificial control for arranging the B-site ion has been demonstrated by superlattices to elucidate relaxor behavior. The relaxor behavior of ferroelectric material depends on order state of the constructing ion in the crystal. To clarify the mechanism of this relaxor behavior, Ba(Zr,Ti)O3 is chosen as the target material because its B-site ions are not naturally ordered. The superlattice samples were prepared by using a pulsed laser deposition (PLD) technique. Observed X-ray diffraction (XRD) patterns of the superlattices and their theoretical calculation revealed that the degree of order state was well controlled by our technique. The relaxor behavior occurs in the order degree (OD) ratio below -25% indicating that the OD is a key function for determining the origin of the relaxor behavior.

Hotta, Yasushi; Hassink, G. W. J.; Kawai, Tomoji; Tabata, Hitoshi

2003-09-01

375

Ferroelectric electron emission: Principles and technology  

NASA Astrophysics Data System (ADS)

The spontaneous electrical polarization of ferroelectric materials can be changed either by reversal or by phase transition from a ferroelectric into a non-ferroelectric state or vice versa. If spontaneous polarization changes are induced with fast heat, mechanical pressure, laser or electric field pulses on a submicrosecond time scale, strong uncompensated surface charge densities and related polarization fields are generated, which may lead to the intense self-emission of electrons from the negatively charged free surface areas of the ferroelectric sample. Hence, electron guns can be built with extraction-field-free ferroelectric cathodes, which may be easily separated from the high-field regions of post-accelerating gap structures. The intensity, the energy, the temporal and spatial distribution, and the repetitition rate of the emitted electron beams can be controlled within wide limits via the excitation pulses and external focusing and accelerating electromagnetic fields. The technological advantages and difficulties of ferroelectric cathodes during production and in practical operation are identified and discussed. A new design of electron guns with ferroelectric cathodes is described. Experience with a few applications of ferroelectric electron emission is reported and suggestions for further applications are made.

Riege, H.

1997-02-01

376

Observation of Ferroelectric Domain Structure in TGS  

Microsoft Academic Search

Triglycine sulfate (TGS) is one of the most intensively investigated ferroelectrics. Though the domain structure is an important subject in the research of ferroelectricity, the domain in TGS is invisible by usual optical method. Many substitutive methods have been developed for the observation of static and dynamic domain structure in TGS. This review summarizes these methods mainly from a practical

N. Nakatani

2011-01-01

377

A concept of ferroelectric microparticle propulsion thruster  

SciTech Connect

A space propulsion concept using charged ferroelectric microparticles as a propellant is suggested. The measured ferroelectric plasma source thrust, produced mainly by microparticles emission, reaches {approx}9x10{sup -4} N. The obtained trajectories of microparticles demonstrate that the majority of the microparticles are positively charged, which permits further improvement of the thruster.

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

2008-02-25

378

Ferroelectric translational antiphase boundaries in nonpolar materials.  

PubMed

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

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

2014-01-01

379

Why are there so few perovskite ferroelectrics?  

NASA Astrophysics Data System (ADS)

Nearly all cubic ABO3 perovskites are unstable to energy-lowering structural distortions, the most common being those that give rise to ferroelectricity (usually an off-centering of the B-site cation) and tilts or rotations of the BO6 octahedra. Whereas there are many perovskites that are either ferroelectric or have rotated octahedra, there are very few perovskites that are both ferroelectric and have rotated octahedra. This observation has lead to the widespread assumption that rotations suppress ferroelectricity and vice versa. Using first-principles density functional theory calculations, in combination with crystal chemistry and symmetry principles, we show that rotations do not always suppress ferroelectricity. In fact, the most fertile place to search for new ferroelectrics may be the place that has thus far been considered the least likely to contain them: materials that are expected to have large rotations. We will show why and how ferroelectricity is suppressed in the most common space group adopted by perovskites (Pnma) and explain how we can use this knowledge to design new ferroelectrics and functional materials.

Benedek, Nicole; Fennie, Craig

2013-03-01

380

Thin film ferroelectric materials for microbolometer arrays  

Microsoft Academic Search

This paper reviews the use of thin film ferroelectric materials for application in microbolometer infrared detector arrays. A key issue is the need for high temperature processing to achieve the required ferroelectric crystal phase. Results of thermal trials on silicon readout circuits are presented which indicate failure due to disruption of the AlCuSi metallisation. Higher temperatures can be used if

Michael A. Todd; Paul A. Manning; Paul P. Donohue; Alan G. Brown; Rex Watton

2000-01-01

381

Multiferroics: a magnetic twist for ferroelectricity  

Microsoft Academic Search

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

Sang-Wook Cheong; Maxim Mostovoy

2007-01-01

382

Active control of ferroelectric switching using defect-dipole engineering.  

PubMed

Active control of defect structures and associated polarization switching in a ferroelectric material is achieved without compromising its ferroelectric properties. Based on dipolar interaction between defect dipole and polarization, the unique functionality of the defect dipole to control ferroelectric switching is visualized. This approach can provide a foundation for novel ferroelectric applications, such as high-density multilevel data storage. PMID:23023876

Lee, Daesu; Jeon, Byung Chul; Baek, Seung Hyub; Yang, Sang Mo; Shin, Yeong Jae; Kim, Tae Heon; Kim, Yong Su; Yoon, Jong-Gul; Eom, Chang Beom; Noh, Tae Won

2012-12-18

383

Constrained polarization study of ferroelectric KNO3  

NASA Astrophysics Data System (ADS)

Potassium nitrate has an interesting phase diagram that includes a reentrant ferroelectric phase (phase III, R3m), and it has been proposed as a promising material to be used in random-access memory devices. Recently, we have developed a method to compute the ground-state of an insulator under a fixed value of its polarization that can be used to gain insight into the properties of polar materials. In this talk we show the results of applying this method to study the structural behavior of potassium nitrate under polarization reversal, describing an unusual mechanism in which the reversal is accompanied by a rotation of the NO3 unit by 60^o. We also use our calculations as a basis for constructing first-principles based models that can be used to gain a deeper understanding of the switching behavior of this material. J. F. Scott, M. S. Zhang, R. B. Godfrey, C. Araujo, and L. McMillan, Phys. Rev. B 35, 4044 (1987). See: cond-mat/0511711 (www.arXiv.org).

Diéguez, Oswaldo; Vanderbilt, David

2006-03-01

384

Size dependent polarization reversal at nanoscale metal-ferroelectric interfaces  

NASA Astrophysics Data System (ADS)

Ferroelectric oxides possess a unique set of physical properties that have not been maximally exploited due to a lack of understanding of the origins of the switching behavior. Currently, controversy exists over whether switching in ferroelectric oxides is due to polarization or defect mediated switching. Here, we use ultra-high vacuum scanning tunneling microscopy and atomic force microscopy to investigate the process of polarization reversal and to assess the effect of the electronic structure and conductance on the switching behavior of single crystal BaTiO3 (001). Measurements of the local density of states revealed the surface switching behavior was initially due to polarization and that a transition occurred to defected mediated switching after repeated switching cycles. Atomic force microscopy investigations of the size effects at nanoscale Au-BaTiO3 (001) interfaces revealed asymmetric polarization reversal at large interfaces with a convergence to symmetric behavior as the size scale decreased, in agreement with the tunneling-based scanning tunneling microscopy technique.

Kraya, R. A.; Kraya, L. Y.

2012-12-01

385

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

Microsoft Academic Search

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.

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

2000-01-01

386

Photorefractivity in ferroelectric liquid crystal composites containing electron donor and acceptor molecules.  

SciTech Connect

The first observation of photorefractivity in ferroelectric liquid crystals (FLCs) is reported here. Dopant chromophores chosen to optimize production of mobile ions and careful control of the wavevector and light polarization are believed to play a decisive role in the observed behavior. The Figure is a schematic illustration of the experimental geometry used.

Wiederrecht, G. P.; Yoon, B. A.; Wasielewski, M. R.; Chemistry; Northwestern Univ.

2000-10-16

387

Synthesis and Properties of Side Chain Ferroelectric Liquid Crystalline Polyacetylene Derivatives  

Microsoft Academic Search

Novel liquid crystalline (LC) polyacetylene derivatives were synthesized to develop advanced LC conducting polymers with an ability of quick response to an electric field used as an external force. In practice, we synthesized ferroelectric LC conducting polymers by introducing fluorine-containing chiral LC groups into side chains of polyacetylenes. Phase transition behaviors of these polymers were examined by differential scanning calorimeter

Xiaoman Dai; Hiromasa Goto; Kazuo Akagi

2001-01-01

388

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

Microsoft Academic Search

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

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

2002-01-01

389

Microscopic mechanisms for improper ferroelectricity in multiferroic perovskites: a theoretical review  

SciTech Connect

Two microscopic mechanisms helping us to understand the multiferroic behavior of distorted rare-earth manganites are here briefly reviewed. The original work was carried out by means of Hamiltonian modeling and first-principles density functional simulations. Our first topic concerns the link between the Dzyaloshinskii Moriya interaction and ferroelectricity in incommensurate magnets. We argue that the Dzyaloshinskii Moriya interaction may play a key role since (i) it induces ferroelectric displacements of oxygen atoms and (ii) it favors the stabilization of a helical magnetic structure at low temperatures. Our second topic concerns the prediction, based on Landau theory, that the symmetry of the zigzag spin chains in the AFM-E (E-type antiferromagnetic) orthorhombic manganites (such as HoMnO3) allows a finite polarization along the c axis. The microscopic mechanism at the basis of ferroelectricity is interpreted through a gain in band energy of the eg electrons within the orbitally degenerate double-exchange model. Related Monte Carlo simulations have confirmed that the polarization can be much higher than what is observed in spiral magnetic phases. Density functional calculations performed on orthorhombic HoMnO3 quantitatively confirm a magnetically induced ferroelectric polarization up to 6 C cm 2, the largest reported so far for improper magnetic ferroelectrics. We find in HoMnO3, in addition to the conventional displacement mechanism, a sizable contribution arising from the purely electronic effect of orbital polarization. The relatively large ferroelectric polarization, present even with centrosymmetric atomic positions, is a clear sign of a magnetism-induced electronic mechanism at play, which is also confirmed by the large displacements of the Wannier function centers with respect to the corresponding ions in AFM-E HoMnO3. The final polarization is shown to be the result of competing effects, as shown by the opposite signs of the eg and t2g contributions to the ferroelectric polarization.

Picozzi, S. [CNR-INFM, L-Aquila, Italy; Yamauchi, K. [CNR-INFM, L-Aquila, Italy; Sergienko, Ivan A [ORNL; Sen, Cengiz [Florida State University; Sanyal, B. [Uppsala University, Uppsala, Sweden; Dagotto, Elbio R [ORNL

2008-01-01

390

Interface-Induced Polarization and Inhibition of Ferroelectricity in Epitaxial SrTiO3=Si  

SciTech Connect

We use SrTiO{sub 3}/Si as a model system to elucidate the effect of the interface on ferroelectric behavior in epitaxial oxide films on silicon. Using both first-principles computations and synchrotron x-ray diffraction measurements, we show that structurally imposed boundary conditions at the interface stabilize a fixed (pinned) polarization in the film but inhibit ferroelectric switching. We demonstrate that the interface chemistry responsible for these phenomena is general to epitaxial silicon-oxide interfaces, impacting on the design of silicon-based functional oxide devices.

Su, D.; Kolpak, A.M.; Walker, F.J.; Reiner, J.W.; Segal, Y.; Sawicki, M.S.; Broadbridge, C.C.; Zhang, Z.; Zhu, Y.; Ahn, C.H.; Ismail-Beigi, S.

2010-11-17

391

Interface-induced polarization and inhibition of ferroelectricity in Epitaxial SrTiO3/Si.  

SciTech Connect

We use SrTiO{sub 3}/Si as a model system to elucidate the effect of the interface on ferroelectric behavior in epitaxial oxide films on silicon. Using both first-principles computations and synchrotron x-ray diffraction measurements, we show that structurally imposed boundary conditions at the interface stabilize a fixed (pinned) polarization in the film but inhibit ferroelectric switching. We demonstrate that the interface chemistry responsible for these phenomena is general to epitaxial silicon-oxide interfaces, impacting on the design of silicon-based functional oxide devices.

Kolpak, A.M.; Walker, F.J.; Reiner, J.W.; Segal, Y.; Su, D.; Sawicki, M.S.; Broadbridge, C.C.; Zhang, Z.; Zhu, Y.; Ahn, C.H.; Ismail-Beigi, S. (X-Ray Science Division); (Yale Univ.); (Brookhaven National Laboratory); (Southern Connecticut State University)

2010-11-19

392

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

SciTech Connect

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.

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

393

Pressure tuned ferroelectric reentrance in nano-BaTiO3 ceramics  

NASA Astrophysics Data System (ADS)

In nano-grain BaTiO3 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.

Zhu, J. L.; Lin, S.; Feng, S. M.; Wang, L. J.; Liu, Q. Q.; Jin, C. Q.; Wang, X. H.; Zhong, C. F.; Li, L. T.; Cao, Wenwu

2012-12-01

394

Raman scattering spectra of ceramics, films, and superlattices of ferroelectric perovskites: A review  

NASA Astrophysics Data System (ADS)

Raman investigations of the crystal lattice dynamics in classical ferroelectric perovskites SrTiO3, PbTiO3, and BaTiO3 have been analyzed. The specific features revealed in the behavior of soft modes during the phase transitions occurring in ceramics and powders of these compounds, as well as in several related solid solutions, have been described. Particular attention has been paid to the investigations of ferroelectric thin films and superlattices in which the sequences of structural distortions can be radically different from those known for the initial bulk materials.

Yuzyuk, Yu. I.

2012-05-01

395

Magnetic control of ferroelectric interfaces  

Microsoft Academic Search

We report the strong magnetic field dependence of ferroelectric PbZr0.52Ti0.48O3 (PZT) films on half-metallic oxide La0.67Sr0.33MnO3 (LSMO) electrodes. As the field H is increased, the hysteresis loop first broadens (becomes lossy) and then disappears at approximately H = 0.34 T and ambient temperatures. The data are compared with the theories of Pirc et al (2009 Phys. Rev. B 79 214114),

S. Dussan; A. Kumar; R. S. Katiyar; S. Priya; J. F. Scott

2011-01-01

396

Calligraphic Poling of Ferroelectric Material  

NASA Technical Reports Server (NTRS)

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.

Mohageg, Makan; Strekalov, Dmitry; Savchenkov, Anatoliy; Matsko, Adrey; Maleki, Lute; Iltchenko, Vladimir

2007-01-01

397

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

SciTech Connect

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.

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

398

Scanning force microscopy of domain structure in ferroelectric thin films : imaging and control.  

SciTech Connect

Scanning force microscopy (SFM) has been used to perform nanoscale studies of domain structures and switching behavior of Pb(Zr{sub x}Ti{sub L-x})O{sub 3} (PZT) thin films. An SFM piezoresponse mode, based on the detection of the piezoelectric vibration of a ferroelectric sample, was shown to be suitable for high resolution imaging of ferroelectric domains in thin films. The lower limit of the piezoresponse mode imaging resolution depends on the radius of the probing tip and is estimated to be of the order of several nanometers. The effect of the film microstructure on the imaging resolution is discussed. The ability of effective control of domains as small as 50 nm by means of SFM has been demonstrated. It is shown that SFM can be used in the investigation of electrical degradation effects in ferroelectric thin films. Formation of regions with unswitchable polarization as a result of fatigue, within grains of submicron size, was experimentally observed.

Gruverman, A.; Auciello, O.; Tokumoto, H.; Materials Science Division; Joint Research Center for Atom Tech.

1997-01-01

399

Universal Ferroelectric Switching Dynamics of Vinylidene Fluoride-trifluoroethylene Copolymer Films  

NASA Astrophysics Data System (ADS)

In this work, switching dynamics of poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] copolymer films are investigated over unprecedentedly wide ranges of temperature and electric field. Remarkably, domain switching of copolymer films obeys well the classical domain nucleation and growth model although the origin of ferroelectricity in organic ferroelectric materials inherently differs from the inorganic counterparts. A lower coercivity limit of 50 MV/m and 180° domain wall energy of 60 mJ/m2 are determined for P(VDF-TrFE) films. Furthermore, we discover in copolymer films an anomalous temperature-dependent crossover behavior between two power-law scaling regimes of frequency-dependent coercivity, which is attributed to the transition between flow and creep motions of domain walls. Our observations shed new light on the switching dynamics of semi-crystalline ferroelectric polymers, and such understandings are critical for realizing their reliable applications.

Hu, Wei Jin; Juo, Deng-Ming; You, Lu; Wang, Junling; Chen, Yi-Chun; Chu, Ying-Hao; Wu, Tom

2014-04-01

400

Universal ferroelectric switching dynamics of vinylidene fluoride-trifluoroethylene copolymer films.  

PubMed

In this work, switching dynamics of poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] copolymer films are investigated over unprecedentedly wide ranges of temperature and electric field. Remarkably, domain switching of copolymer films obeys well the classical domain nucleation and growth model although the origin of ferroelectricity in organic ferroelectric materials inherently differs from the inorganic counterparts. A lower coercivity limit of 50?MV/m and 180° domain wall energy of 60?mJ/m(2) are determined for P(VDF-TrFE) films. Furthermore, we discover in copolymer films an anomalous temperature-dependent crossover behavior between two power-law scaling regimes of frequency-dependent coercivity, which is attributed to the transition between flow and creep motions of domain walls. Our observations shed new light on the switching dynamics of semi-crystalline ferroelectric polymers, and such understandings are critical for realizing their reliable applications. PMID:24759786

Hu, Wei Jin; Juo, Deng-Ming; You, Lu; Wang, Junling; Chen, Yi-Chun; Chu, Ying-Hao; Wu, Tom

2014-01-01

401

Attenuation characteristics of the guided THz wave in parallel-plate ferroelectric-graphene waveguides  

NASA Astrophysics Data System (ADS)

Guided THz wave characteristics in a parallel-plate waveguide (PPWG) consisting of ferroelectric film (LiNbO3 and LiTaO3) and multilayer graphene (MLG) is studied in this paper, with their low and tunable attenuation valley predicted. The electrical conductivity of MLG is calculated by a set of closed-form equations with the coupling effect between the bottom graphene layer (BGL) and its substrate taken into account carefully, while the dispersive behavior of ferroelectric film itself is described by the Lorentz model over an ultra-wide THz band. It is shown that the guided TM-mode propagation can be adjusted effectively by changing temperature, frequency, optical pumping intensity, MLG layer number, film thickness and its transverse optical-phonon frequency. Moreover, one low attenuation valley of TM-mode in such ferroelectric-graphene waveguide is captured, which can be exploited for developing some THz planar tunable waveguides with ultra-low loss.

Gu, Xiao-Qiang; Yin, Wen-Yan; Zheng, Ting

2014-11-01

402

Constrained ferroelectricity in BaTiO3/BaZrO3 superlattices  

NASA Astrophysics Data System (ADS)

BaTiO3/BaZrO3 superlattices with varying periodicities were grown on SrRuO3 buffered MgO (001) substrates by pulsed laser ablation. Ferroelectric measurements were done and correlated to the strain in the heterostructures. The results of ferroelectric measurements indicate an apparent suppression of polarization in the low period superlattices and the onset of weakly ferroelectric behavior in higher period superlattices. Measured switchable polarization values indicate that contribution is primarily from the BaTiO3 in the structure. These results have been correlated to the interfacial strain and the critical thickness of BaTiO3 when grown over tensile substrates such as MgO.

Roy Choudhury, Palash; Krupanidhi, S. B.

2008-03-01

403

Low temperature dependent ferroelectric resistive switching in epitaxial BiFeO3 films  

NASA Astrophysics Data System (ADS)

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.

Yan, F.; Xing, G. Z.; Li, L.

2014-03-01

404

FAST TRACK COMMUNICATION: Statistical switching kinetics of ferroelectrics  

NASA Astrophysics Data System (ADS)

By assuming a more realistic nucleation and polarization reversal scenario we build a statistical switching model for polycrystalline ferroelectrics, which is different from both the Kolmogorov-Avrami-Ishibashi (KAI) model and the nucleation-limited-switching model. After incorporating a time-dependent depolarization field, this model gives a good explanation of the retardation behavior in polycrystalline thin films at medium or low fields, which cannot be described using the traditional KAI model. This model predicts n = 1 for polycrystalline thin films at high fields or ceramic bulks in the ideal case, in good agreement with the experimental data previously published.

Lou, X. J.

2009-01-01

405

A ferroelectric-semiconductor-coupled solar cell with tunable photovoltage  

NASA Astrophysics Data System (ADS)

To confirm the feasibility of nanodipole photovoltaic devices, we designed a practicable method of phase segregation to extract CdS piezoelectric nanoparticles from CdSTe mixed film. The constituent components of such device are mixture of ferroelectric CdS nanodipoles and CdTe semiconductor absorber. We observed an analogous electric hysteresis of photovoltage in such devices. Piezoresponse grain boundaries are observed, which contribute significantly to the hysteresis behavior of photovoltage. Abnormal photovoltage polarity of CdS nanodipole devices is also observed. But such phenomena cannot be explained by classical junctional device theory. We believe these provide convincing evidence for the mechanism of nanodipoles.

Huang, Fang; Liu, Xiangxin

2013-03-01

406

Substrate effects on the ferroelectric properties of fine-grained BaTiO3 films  

NASA Astrophysics Data System (ADS)

The development of ferroelectric properties in barium titanate (BaTiO3) polycrystalline films has been investigated as a function of substrate type. The films were deposited by physical vapor deposition (PVD) onto different, Pt-coated substrates (magnesium oxide, thermally oxidized silicon, and sapphire) and annealed at temperatures from 725 to 1050 °C. Grain sizes from 50 to 200 nm were produced, with structural and dielectric properties that showed a marked transition from nonferroelectric to ferroelectric behavior across this range. Anneal temperatures below 950 °C result in films with grain sizes less than 150 nm, and ferroelectric properties that are strongly suppressed, regardless of the substrate. Observations for this temperature range include low dielectric constant (?), no polarization hysteresis, and no peaks in the temperature dependence of the dielectric constant. The onset of ferroelectric behavior occurs for anneal temperatures above 950 °C, coinciding with the appearance of strong substrate effects on the dielectric properties. Such BaTiO3 films on Pt/MgO show the largest dielectric constant, remnant polarization, and temperature dependence of ?, while films on Pt/sapphire exhibit the weakest of each of these properties. Films on Pt/barrier/Si exhibit dielectric properties with values in between that of films on Pt/MgO and Pt/sapphire. The dependence of BaTiO3 ferroelectric properties on the substrate is related to a combination of the BaTiO3 grain and size orientation, determined partly by the underlying Pt surface, and to the thermal expansion properties of the substrate. However, these factors only influence the BaTiO3 dielectric properties for those films that exhibit ferroelectric properties. In this way, the anneal temperature and substrate dependence of the films are linked.

Ring, Ken M.; Kavanagh, Karen L.

2003-11-01

407

Modeling of ferroelectric-ferromagnetic composites to improve magnetoelectric coupling and durability  

NASA Astrophysics Data System (ADS)

The coupling of magnetic and electric fields due to the constitutive behavior of a material is commonly denoted as ME-effect. The latter is only observed in a few crystal classes exhibiting a very weak coupling which can hardly be exploited for technical applications. Much larger coupling coefficients are obtained in so called multiferroic composite materials, where ferroelectric and ferromagnetic constituents are embedded in a matrix. The MEeffect is then induced by the strain of the matrix converting electrical and magnetic energies based on the ferroelectric and magnetostrictive effects. In this paper, the theoretical background of nonlinear constitutive multifield behavior as well as the Finite Element implementation are presented. Nonlinear material models describing the magneto-ferroelectric behavior are presented. On this basis, the poling process in the ferroelectric phase is simulated and resulting effects are analyzed. Numerical simulations in general focus on the prediction of ME coupling coefficients and residual stresses going along with the poling process. Numerical homogenization, here, is a useful means to supply effective properties.

Ricoeur, Andreas; Avakian, Artjom; Wang, Zhibin

2014-03-01

408

Structural Consequences of Ferroelectric Nanolithography  

SciTech Connect

Domains of remnant polarization can be written into ferroelectrics with nanoscale precision using scanning probe nanolithography techniques such as piezoresponse force microscopy (PFM). Understanding the structural effects accompanying this process has been challenging due to the lack of appropriate structural characterization tools. Synchrotron X-ray nanodiffraction provides images of the domain structure written by PFM into an epitaxial Pb(Zr,Ti)O{sub 3} thin film and simultaneously reveals structural effects arising from the writing process. A coherent scattering simulation including the superposition of the beams simultaneously diffracted by multiple mosaic blocks provides an excellent fit to the observed diffraction patterns. Domains in which the polarization is reversed from the as-grown state have a strain of up to 0.1% representing the piezoelectric response to unscreened surface charges. An additional X-ray microdiffraction study of the photon-energy dependence of the difference in diffracted intensity between opposite polarization states shows that this contrast has a crystallographic origin. The sign and magnitude of the intensity contrast between domains of opposite polarization are consistent with the polarization expected from PFM images and with the writing of domains through the entire thickness of the ferroelectric layer. The strain induced by writing provides a significant additional contribution to the increased free energy of the written domain state with respect to a uniformly polarized state.

J Young Jo; P Chen; R Sichel; S Bake; R Smith; N Balke; S Kalinin; M Holt; J Maser; et al.

2011-12-31

409

Structural consequences of ferroelectric nanolithography.  

PubMed

Domains of remnant polarization can be written into ferroelectrics with nanoscale precision using scanning probe nanolithography techniques such as piezoresponse force microscopy (PFM). Understanding the structural effects accompanying this process has been challenging due to the lack of appropriate structural characterization tools. Synchrotron X-ray nanodiffraction provides images of the domain structure written by PFM into an epitaxial Pb(Zr,Ti)O(3) thin film and simultaneously reveals structural effects arising from the writing process. A coherent scattering simulation including the superposition of the beams simultaneously diffracted by multiple mosaic blocks provides an excellent fit to the observed diffraction patterns. Domains in which the polarization is reversed from the as-grown state have a strain of up to 0.1% representing the piezoelectric response to unscreened surface charges. An additional X-ray microdiffraction study of the photon-energy dependence of the difference in diffracted intensity between opposite polarization states shows that this contrast has a crystallographic origin. The sign and magnitude of the intensity contrast between domains of opposite polarization are consistent with the polarization expected from PFM images and with the writing of domains through the entire thickness of the ferroelectric layer. The strain induced by writing provides a significant additional contribution to the increased free energy of the written domain state with respect to a uniformly polarized state. PMID:21728277

Jo, Ji Young; Chen, Pice; Sichel, Rebecca J; Baek, Seung-Hyub; Smith, Ryan T; Balke, Nina; Kalinin, Sergei V; Holt, Martin V; Maser, Jörg; Evans-Lutterodt, Kenneth; Eom, Chang-Beom; Evans, Paul G

2011-08-10

410

Photorefractive effect in ferroelectric liquid crystals  

NASA Astrophysics Data System (ADS)

In this paper, we review recent progress of research on the photorefractive effect of ferroelectric liquid crystals. The photorefractive effect is a phenomenon that forms a dynamic hologram in a material. The interference of two laser beams in a photorefractive material establishes a refractive index grating. This phenomenon is applicable to a wide range of devices related to diffraction optics including 3D displays, optical amplification, optical tomography, novelty filters, and phase conjugate wave generators. Ferroelectric liquid crystals are considered as a candidate for practical photorefractive materials. A refractive index grating formation time of 8-10 ms and a large gain coefficient are easily obtained in photorefractive ferroelectric liquid crystals.

Sasaki, Takeo; Naka, Yumiko

2014-03-01

411

Interplay of ferroelectricity and single electron tunneling  

NASA Astrophysics Data System (ADS)

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).

Fedorov, S. A.; Korolkov, A. E.; Chtchelkatchev, N. M.; Udalov, O. G.; Beloborodov, I. S.

2014-04-01

412

One-dimensional nanostructures of ferroelectric perovskites.  

PubMed

Nanorods, nanowires, and nanotubes of ferroelectric perovskites have recently been studied with increasing intensity due to their potential use in non-volatile ferroelectric random access memory, nano-electromechanical systems, energy-harvesting devices, advanced sensors, and in photocatalysis. This Review summarizes the current status of these 1D nanostructures and gives a critical overview of synthesis routes with emphasis on chemical methods. The ferroelectric and piezoelectric properties of the 1D nanostructures are discussed and possible applications are highlighted. Finally, prospects for future research within this field are outlined. PMID:21796684

Rørvik, Per Martin; Grande, Tor; Einarsrud, Mari-Ann

2011-09-15

413

Cyclic Cluster Growth in Ferroelectric Perovskites  

Microsoft Academic Search

We prove that point defect clustering in perovskite ferroelectrics and the subsequent loss in switchable polarization can occur only if the depolarizing fields are locally unscreened during certain fractions of time in each of the multiple bipolar electric field cycles.

Doru C. Lupascu; Ute Rabe

2002-01-01

414

Ferroelectric Liquid Crystal Optical Interconnect Switching Systems.  

National Technical Information Service (NTIS)

This grant explored the possible use of ferroelectric liquid crystals (FLC's) in the reamization of photonic switching fabrics. Problems addressed included device fabrication, switch architectures, and switch performance. Experimental versions of most arc...

J. W. Goodman

1993-01-01

415

Interface control of bulk ferroelectric polarization  

SciTech Connect

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.

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

416

Ferroelectric control of orbital occupancy in manganites  

NASA Astrophysics Data System (ADS)

Recent successful fabrication of epitaxial and coherent ferroelectric/manganite interfaces makes it possible to dynamically control charge and spin in manganites [1]. We demonstrate with ab initio calculations that in this system, d-orbital occupancies of the interfacial Mn atom can also be modulated by flipping the ferroelectric polarization (i.e. flippable orbital polarization). The underlying mechanism is the structural distortions of the oxygen octahedron and the Mn atom inside induced by the ferroelectric polarization. The in-plane orbital dx^2-y^2 is stablized by rumpling in MnO2 layers, while the Jahn-Teller distortion (c/a>1) favors the out-of-plane orbital d3z^2-r^2. This ferroelectric control of orbital occupancy serves as a new approach separate from strain for engineering orbital orderings in transition metal oxides. [4pt] [1] C.A.F.Vaz et al., Phys. Rev. Lett. 104, 127202 (2010)

Chen, Hanghui; Ismail-Beigi, Sohrab

2012-02-01

417

Improper Ferroelectricity: A Theoretical and Experimental Investigation.  

National Technical Information Service (NTIS)

A combined theoretical and experimental study has been made of the origins and properties of the improper ferroelectricity associated with structural modulations of non-zero wavelengths. Two classes of materials have been studied: rare earth molybdates (s...

J. R. Hardy F. G. Ullman

1984-01-01

418

Scanning for Ferroelectricity in Polycrystalline Materials.  

National Technical Information Service (NTIS)

A method has been developed which can scan rapidly for ferroelectricity in polycrystalline compounds. This consists of measuring the dielectric constant of a polycrystalline pellet as a function of temperature. If any dielectric anomalies are found where ...

M. Litt C. Hsu P. Basu S. M. Aharoni

1974-01-01

419

Ferroelectricity in yttrium-doped hafnium oxide  

NASA Astrophysics Data System (ADS)

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.

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

420

Polarization-modulated rectification at ferroelectric surfaces  

NASA Astrophysics Data System (ADS)

By correlating room temperature conductive atomic force microscopy (c-AFM) with low temperature electrostatic force microscopy (EFM) images taken at different temperatures but the same location, we demonstrate that nanoscale electric conduction between a sharp tip and the surface of ferroelectric HoMnO3 is intrinsically modulated by the polarization of ferroelectric domains. Conductance spectra reveal that the electric conduction is described by polarization-induced Schottky-like rectification at low bias, but dominated by a space-charge limited conduction mechanism at high bias. Our observation demonstrates visualization ferroelectric domain structure by electric conduction, which may be used for non-destructive read-out of nanoscale ferroelectric memories or sensors.

Wu, Weida; Horibe, Y.; Park, S.; Choi, T.; Cheong, S.-W.; Kim, S. B.; Guest, J. R.; Bode, M.

2010-03-01

421

Ferroelectric vortices from atomistic simulations  

NASA Astrophysics Data System (ADS)

In 2004, the use of a first-principles-based effective Hamiltonian [1] led to the prediction of a novel structure in zero-dimensional ferroelectrics, in which the electric dipoles organize themselves to form a vortex [2]. Such structure exhibits the so-called spontaneous toroidal moment, rather than the spontaneous polarization, as its order parameter [2]. Subsequently, various original phenomena, all related to vortices, were predicted in ferroelectric nanostructures. Examples of such phenomena are: (i) the existence of a new order parameter, denoted as the hypertoroidal moment, that is associated with many complex dipolar structures (such as double-vortex states) [3]; (ii) the possible control of single and double vortex states by electric fields, via the formation of original intermediate states [4-8]; (iii) the discovery of a new class of quantum materials (denoted as incipient ferrotoroidics), for which zero-point vibrations wash out the vortex state and yield a complex local structure [9]; (iv) the existence of chiral patterns of oxygen octahedral tiltings that originate from the coupling of these tiltings with the ferroelectric vortices [10]. The purpose of this talk is to discuss some of these striking phenomena, as well as, to reveal others (if time allows). These studies are done in collaboration with A.R. Akbarzadeh, H. Fu, I. Kornev, I. Naumov, I. Ponomareva, S. Prosandeev, Wei Ren and D. Sichuga. [4pt] [1] L. Bellaiche, A. Garcia and D. Vanderbilt, Phys. Rev. Lett. 84, 5427 (2000). [0pt] [2] Ivan I. Naumov, L. Bellaiche and Huaxiang Fu, Nature (London) 432, 737 (2004). [0pt] [3] S. Prosandeev and L. Bellaiche, Phys. Rev. B 77, 060101(R) (2008). [0pt] [4] S. Prosandeev, I. Ponomareva, I. Kornev, I. Naumov and L. Bellaiche, Phys. Rev. Lett. 96, 237601 (2006). [0pt] [5] I. Naumov and H. Fu, Phys. Rev. Lett. 98, 077603 (2007). [0pt] [6] S. Prosandeev and L. Bellaiche, Phys. Rev. Lett. 101, 097203 (2008). [0pt] [7] S. Prosandeev, I. Ponomareva, I. Kornev, and L. Bellaiche, Phys. Rev. Lett. 100, 047201 (2008). [0pt] [8] I. Naumov and H. Fu, Phys. Rev. Lett. 101, 197601 (2008). [0pt] [9] S. Prosandeev, A. R. Akbarzadeh and L. Bellaiche, Phys. Rev. Lett. 102, 257601(2009). [0pt] [10] David Sichuga, Wei Ren, Sergey Prosandeev, and L. Bellaiche, Phys. Rev. Lett. 104, 207603 (2010).

Bellaiche, Laurent

2011-03-01

422

Ferroelectric memristor based on Pt/BiFeO3/Nb-doped SrTiO3 heterostructure  

NASA Astrophysics Data System (ADS)

We report a continuously tunable resistive switching behavior in Pt/BiFeO3/Nb-doped SrTiO3 heterostructure for ferroelectric memristor application. The resistance of this memristor can be tuned up to 5 × 105% by applying voltage pulses at room temperature, which exhibits excellent retention and anti-fatigue characteristics. The observed memristive behavior is attributed to the modulation effect of the ferroelectric polarization reversal on the width of depletion region and the height of potential barrier of the p-n junction formed at the BiFeO3/Nb-doped SrTiO3 interface.

Hu, Zhongqiang; Li, Qian; Li, Meiya; Wang, Qiangwen; Zhu, Yongdan; Liu, Xiaolian; Zhao, Xingzhong; Liu, Yun; Dong, Shuxiang

2013-03-01

423

Polarization and polarization fatigue in ferroelectrics  

Microsoft Academic Search

This thesis addresses some fundamental issues in ferroelectricity and its applications through a computational and experimental effort. It focuses on a variety of perovskite-type ferroelectric oxides and investigates the physical basis for spontaneous polarization, domain wall dynamics, and texture development in thin film applications. The dipole-dipole interactions between ionic species in perovskite-type materials have been calculated to determine the local

Xiaofeng Du

1997-01-01

424

BARIUM-STROTIUM TITANATE BASED FERROELECTRIC HETEROSTRUCTURES  

Microsoft Academic Search

Ferroelectric properties of heteroepitaxial Ba0.8Sr0.2TiO3 thin films on (001) MgO substrates were studied as a function of film thickness varied from 6 to 980 nm. X-ray diffraction study revealed structural transformation at the film thickness ? 70 nm. Both A1(TO) and E(TO) components of the ferroelectric soft mode exhibited downward shifts near the critical thickness. Dielectric permittivity exhibited maxima in

V. M. MUKHORTOV; Y. U. I. GOLOVKO; P. A. ZELENCHUK; Y. U. I. YUZYUK

2009-01-01

425

Ferroelectric Thin Films for Electronic Applications  

Microsoft Academic Search

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 flexur