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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

Relaxor ferroelectric behavior in Ca-doped TbMnO3  

NASA Astrophysics Data System (ADS)

We have studied the effect of Ca-doping in single-crystal Tb1-xCaxMnO3(x?0.1) on the crystal and magnetic structure, magnetocapacitance, and electric polarization. For low doping (x=0.05) , the presence of Mn4+ ions gives rise to a state with behavior resembling that of a relaxor ferroelectric. The coherence length of the Mn magnetic spin spiral is reduced, while the Mn-modulation wave vector is unchanged. For doping larger than 5%, the ferroelectric state is suppressed, which we ascribe to breakdown of the spiral magnetic structure.

Mufti, N.; Nugroho, A. A.; Blake, G. R.; Palstra, T. T. M.

2008-07-01

4

Mechanical flexible and electric fatigue resistant behavior of relaxor ferroelectric terpolymer  

NASA Astrophysics Data System (ADS)

Uniaxial tension and polarization evolution under cyclic electric field are investigated for poly(vinylidene fluoride-trifluorethylene-chlorofluoroethylene) terpolymer films prepared by different annealing conditions. The stress-strain behavior of the terpolymer film exhibits that of polymeric elastomers, with its fracture strain reaching 680%. Structure analysis demonstrates that the polymer chains undergo reorientation, and conformational change from nonpolar to polar phase takes place during uniaxial tension. Under cyclic electric field, the terpolymer film exhibits a narrow polarization loop typical of a ferroelectric relaxor. Conformational change from nonpolar to polar phase also occurs upon the electric field, and it reverses to the nonpolar phase when the field is removed. As the cycle number accumulates, the terpolymer film demonstrates excellent resistance to electric fatigue. Compared to the film annealed at 115 °C, the terpolymer film annealed at 100 °C has a larger volume fraction of crystallite/amorphous interfaces and shows better mechanical flexibility as well as electric fatigue resistance. The mechanical flexible and electric fatigue resistant terpolymer films hold promises for many applications, ranging from embedded sensors and actuators to flexible memory devices.

Fang, Fei; Yang, Wei; Yang, Wen

2009-08-01

5

Domain Engineered Relaxor Ferroelectric Single Crystals  

NASA Astrophysics Data System (ADS)

Single crystal relaxor ferroelectric materials exhibit extraordinary electromechanical properties. They are being applied in high performance sensors, actuators, and transducers. Field induced polarization switching and phase transitions of these crystals lead to complex nonlinear behavior. In recent years experimental investigations have been conducted to characterize the polarization switching and phase transition behavior as a function of crystallographic orientation, temperature, electric field, and stress. The results give insight into the mechanism underlying the observed large field hysteretic behavior. This review article describes the observed behavior and presents results of multiscale modeling that predicts the macroscopic behavior from the single domain single crystal behavior and evolution of crystal variants at the microscale.

Liu, T.; Lynch, C. S.

2006-08-01

6

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

7

Some microstructural characteristics of relaxor ferroelectrics  

Microsoft Academic Search

A brief description of some of the main uses and dielectric characteristics of ferroelectric relaxor materials is given. Current ideas concerning the microstructural and microchemical origins of the dielectric properties of lead-based perovskite-structured oxide relaxors are presented. The unique ability of transmission electron microscopy to address most of these questions is outlined and illustrated with some recent results on the

D. J. Barber; A. D. Hilton; K. Z. Baba-Kishi

1988-01-01

8

Advances in relaxor ferroelectric terpolymer: New applications  

Microsoft Academic Search

r Abstract-It has been found that by introducing defects into the P(VDF-TrFE) copolymers, it is possible to convert the polymer from a normal ferroelectric to a relaxor ferroelectric. A new class of ferroelectric polymers, i.e., the terpolymers of P(VDF-TrFE­ CFE) or of P(VDF- TrFE-CTFE), was developed from the normal ferroelectric PVDF-TrFE polymer by employing proper defect modifications which eliminate detrimental

Francois Bauer; Jean Fabien Capsal; Quentin Larcher; F. Domingues Dos Santos

2011-01-01

9

A TemperatureDependent Hysteresis Model for Relaxor Ferroelectrics  

E-print Network

. Introduction Actuators constructed from the relaxor ferroelectric material Pb(Mg 1=3 , Nb 2=3 )O 3 (PMNA Temperature­Dependent Hysteresis Model for Relaxor Ferroelectrics Ralph C. Smith 1 and Craig L addresses the development of a temperature­dependent constitutive model for relaxor ferroelectrics which

10

Effects of composition and temperature on the large field behavior of [011]C relaxor ferroelectric single crystals  

NASA Astrophysics Data System (ADS)

The large field behavior of [011]C cut relaxor ferroelectric lead indium niobate-lead magnesium niobate-lead titanate, xPb(In1/2Nb1/2)O3-(1-x-y)Pb(Mg1/3Nb2/3)O3-yPbTiO3, single crystals was experimentally characterized in the piezoelectric d322-mode configuration under combined mechanical, electrical, and thermal loading. Increasing the concentration of lead indium niobate and decreasing the concentration of lead titanate in compositions near the morphotropic phase boundary resulted in a decrease of mechanical compliance, dielectric permittivity, and piezoelectric coefficients as well as a shift from a continuous to a discontinuous transformation.

Gallagher, John A.; Tian, Jian; Lynch, Christopher S.

2014-08-01

11

Ultrahigh strain and piezoelectric behavior in relaxor based ferroelectric single crystals  

NASA Astrophysics Data System (ADS)

The piezoelectric properties of relaxor based ferroelectric single crystals, such as Pb(Zn1/3Nb2/3)O3-PbTiO3 and Pb(Mg1/3Nb2/3)O3-PbTiO3 were investigated for electromechanical actuators. In contrast to polycrystalline materials such as Pb(Zr,Ti)O3, morphotropic phase boundary compositions were not essential for high piezoelectric strain. Piezoelectric coefficients (d33's)>2500 pC/N and subsequent strain levels up to >0.6% with minimal hysteresis were observed. Crystallographically, high strains are achieved for <001> oriented rhombohedral crystals, although <111> is the polar direction. Ultrahigh strain levels up to 1.7%, an order of magnitude larger than those available from conventional piezoelectric and electrostrictive ceramics, could be achieved being related to an E-field induced phase transformation. High electromechanical coupling (k33)>90% and low dielectric loss <1%, along with large strain make these crystals promising candidates for high performance solid state actuators.

Park, Seung-Eek; Shrout, Thomas R.

1997-08-01

12

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

13

Development of “fragility” in relaxor ferroelectrics  

SciTech Connect

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

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

2014-02-07

14

Development of "fragility" in relaxor ferroelectrics  

NASA Astrophysics Data System (ADS)

Relaxor ferroelectrics (RFs), a special class of the disordered crystals or ceramics, exhibit a pronounced slowdown of their dynamics upon cooling as glass-forming liquids, called the "Super-Arrhenius (SA)" relaxation. Despite great progress in glass-forming liquids, the "fragility" property of the SA relaxation in RFs remains unclear so far. By measuring the temperature-dependent dielectric relaxation in the typical relaxor Pb(Mg1/3Nb2/3)O3-x%PbTiO3 (PMN - x%PT) with 0 ? x ? 20.0, we in-depth study the "fragility" properties of the SA relaxation in PMN - x%PT. Such fascinating issues as the mechanism of the "fragility" at an atomic scale, the roles of the systematic configurational entropy change and interaction among relaxing units (RUs, including polar nanoregions and free dipoles) and the relation between "fragility" and ferroelectric order are investigated. Our results show that both the "fragility" of the temperature-dependent SA relaxation and ferroelectric order in the PMN - x%PT systems investigated arise thermodynamically from the configurational-entropy loss due to the attractive interaction among RUs, and develops as a power law, possibly diverging at the finite critical temperature Tc. A reasonable physical scenario, based on our "configurational-entropy-loss" theory and Nowick's "stress-induced-ordering" theory, was proposed.

Wang, Yi-zhen; Chen, Lan; Wang, Hai-yan; Frank Zhang, X.; Fu, Jun; Xiong, Xiao-min; Zhang, Jin-xiu

2014-02-01

15

Pressure as a Probe of the Physics of Relaxor Ferroelectrics  

SciTech Connect

Pressure studies have provided new insights into the physics of compositionally-disordered ABO{sub 3} oxide relaxors. Specifically results are presented and discussed on a pressure-induced ferroelectric-to-relaxor crossover phenomenon, the continuous evolution of the energetics and dynamics of the relaxation process, and the interplay between pressure and electric field in determining the dielectric response.

Samara, George A.

1999-08-09

16

Mechanical flexible and electric fatigue resistant behavior of relaxor ferroelectric terpolymer  

Microsoft Academic Search

Uniaxial tension and polarization evolution under cyclic electric field are investigated for poly(vinylidene fluoride-trifluorethylene-chlorofluoroethylene) terpolymer films prepared by different annealing conditions. The stress-strain behavior of the terpolymer film exhibits that of polymeric elastomers, with its fracture strain reaching 680%. Structure analysis demonstrates that the polymer chains undergo reorientation, and conformational change from nonpolar to polar phase takes place during uniaxial

Fei Fang; Wei Yang; Wen Yang

2009-01-01

17

Relaxor ferroelectrics for electrostrictive transducers: Electrostrictive strain/dielectric properties of relaxor ferroelectrics  

NASA Astrophysics Data System (ADS)

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 electrostrictive effects are advantageous for several reasons: (1) The field-induced deformations (strains) are more stable than in piezoelectric ceramics (relaxation processes are minor and they do not evidence aging from macrodomain-defect interactions), (2) Hysteresis in the strain-field dependence is reduced over a wide temperature range-- the original dimension is returned to rapidly after removal of the polarizing field (reduced creep and strain offset), and (3) Thermal expansion effects are quite small in the relevant temperature range of maximum dielectric permittivity.

1991-08-01

18

Local structure in perovskite relaxor ferroelectrics: high-resolution 93  

E-print Network

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

Vold, Robert

19

Tunability and relaxor properties of ferroelectric barium stannate titanate ceramics  

NASA Astrophysics Data System (ADS)

Barium stannate titanate [Ba(SnxTi1-x)O3, x =0.1, 0.2, 0.3, and 0.4] ceramics were prepared using a conventional solid-state reaction process. Their dielectric properties were measured under direct current bias fields ranging from 0to2.5kV/cm. A transformation from normal to relaxor ferroelectrics was observed when x ?0.3. Broken long-range order or "dirty" ferroelectric domains and nanodomains were observed in Ba(Sn0.1Ti0.9)O3 and Ba(Sn0.4Ti0.6)O3 by transmission electron microscopy, respectively. Voltage driven tunability was found to decrease with increasing Sn content. The change from normal ferroelectric into relaxor ferroelectric had a negative impact on the tunability value of the materials.

Lu, S. G.; Xu, Z. K.; Chen, Haydn

2004-11-01

20

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

21

Pressure as a probe of the physics of relaxor ferroelectrics  

SciTech Connect

Pressure studies have provided new insights into the physics of compositionally-disordered ABO{sub 3} oxide relaxors. Specifically, results will be presented and discussed on a pressure-induced ferroelectric-to-relaxer crossover phenomenon, the continuous evolution of the energetic and dynamics of the relaxation process, and the interplay between pressure and electric field in determining the dielectric response.

SAMARA,GEORGE A.

2000-01-25

22

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

23

Constitutive and failure models for relaxor ferroelectric ceramics  

NASA Astrophysics Data System (ADS)

A non-linear constitutive model for relaxor ferroelectrics developed by Hom and Shankar is examined and verified with electromechanical experiments. This model links polarization and strain to the electric field and stress in an electrostrictive material. A set of tests were performed to study the quasi-static electrical behavior of PMN-PT-BT materials under prestress. Another set of tests investigate the effect of DC electric field on the elastic modulus of the material. The results show excellent correlation between the predicted behavior of the model and the experiments. Failure models for electrostrictive ceramic materials are presented which address the issues of actuator reliability. The constitutive model of Hom and Shankar is incorporated into a nonlinear finite element code. A new finite element technique for computing the J-Integral for cracks in electromechanical materials is developed. This technique is based on the domain integral method and computes both the mechanical and electrical contributions to the energy release rate. The finite element code and the J-Integral computation are used to study crack growth in multilayered electrostrictive ceramic actuators.

Hom, Craig L.; Brown, Steven A.; Shankar, Natarajan

1996-05-01

24

Molecular Dynamics Studies of Structure, Dynamics and Dielectric Response in a Relaxor Ferroelectric  

NASA Astrophysics Data System (ADS)

Since the first synthesis of the classic PbMg1/3Nb2/3O3 (PMN) material in 1961, relaxor ferroelectrics have been the subject of ongoing experimental and theoretical investigation due to their fundamental scientific interest and their importance in technological applications. We use atomistic molecular dynamics simulations to study relaxor behavior in the 0.75PMN-0.25PT material. Even for a fairly small simulation size of 1000 atoms, the system exhibits frequency dispersion and deviation from the Curie-Weiss law typical of relaxor materials. Analysis of the time autocorrelation functions for individual atoms allows us to identify the Nb atoms with a high concentration of neighboring Ti atoms as the nucleation sites for the relaxor behavior. This is due to the higher coupling between the cation displacements induced by the presence of overbonded oxygen atoms. We also analyze local structure and dynamics in PMN-PT using instantaneous, time-averaged and frequency resolved pair distribution functions (PDF). We find that dynamic Pb and Ti off-centering is present even in the paraelectric phase, below Tb the rate of growth of local Pb off-centering increases, followed by the freezing in of the local displacement direction at an intermediate temperature Tc and a transition to a ferroelectric-like phase at Tf. Thus there is a sequence of four phases, PE, dynamic relaxor, mixed dynamic and frozen phase, and the non-ergodic frozen relaxor phase. We identify the average instantaneous local cation off-centering as the order parameter for the dynamic relaxor phase, and the time-averaged local cation off-centering as the order parameter for the two lower-temperatures relaxor phases. Examination of the dynamic PDF data reveals the shape and the range of correlation between the cation displacements. We also show that the relaxor phase is characterized by the appearance of strong nearest-neighbor correlation between the off-center displacements along the Cartesian directions.

Grinberg, Ilya

2012-02-01

25

Mesoscopic cell structure of relaxor ferroelectrics at morphotropic phase boundary  

NASA Astrophysics Data System (ADS)

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

Ahn, Sang-Jin; Kim, Jong-Jean

2003-03-01

26

Crossover from glassy to inhomogeneous-ferroelectric nonlinear dielectric response in relaxor ferroelectrics.  

PubMed

The temperature dependence of the dielectric nonlinearities in a PMN single crystal and in 9/65/35 PLZT ceramics has been determined by measuring the first and third harmonic response as well as the dielectric behavior as a function of the dc electric field. In zero field a paraelectric-to-glass, and, in a high enough dc field, a glass-to-ferroelectriclike crossover in the temperature dependence of the nonlinear response have been observed. Both crossovers agree with the predictions of the spherical random-bond-random-field model. Relaxors thus undergo in zero field a transition to a spherical glass, while above the critical field a transition into a ferroelectric state occurs. PMID:10991081

Bobnar, V; Kutnjak, Z; Pirc, R; Blinc, R; Levstik, A

2000-06-19

27

Relaxor-based ferroelectric single crystals for electromechanical actuators  

NASA Astrophysics Data System (ADS)

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 (PZT's), morphotropic phase boundary compositions were not essential for high piezoelectric strain. Piezoelectric coefficients (d33's) > 2500 pC/N and subsequent strain levels up to > 0.6% with minimal hysteresis were observed. Crystallographically, high strains are achieved for <001> oriented rhombohedral crystals, though <111> is the polar direction. Ultrahigh strain levels up to 1.7%, an order of magnitude larger than those available from conventional piezoelectric and electrostrictive ceramics could be achieved, being related to an E-field induced phase transformation. Strain vs. E-field behavior under external stress was also much superior to that of conventional piezoelectric ceramics. High electromechanical coupling (k33) > 90% and low dielectric loss <1%, along with large strain make these crystals promising candidates for high performance solid state actuators.

Park, Seung Eek E.; Vedula, Venkata; Pan, Ming-Jen; Hackenberger, Wesley S.; Pertsch, Patrick; Shrout, Thomas R.

1998-07-01

28

Classical or relaxor ferroelectric ceramics in the BaTiO 3-KNbO 3-CaTiO 3 system  

NASA Astrophysics Data System (ADS)

In perovskites, the relaxor behavior occurs dominantly in lead based compositions. The study of the BaTiO 3-KNbO 3 binary diagram provided previously evidence for new free from lead ferroelectric relaxor properties but unfortunately at low temperature. The present dielectric studies of ceramics with composition inside the BaTiO 3-KNbO 3-CaTiO 3 showed some of them to be ferroelectric relaxor at temperature close to 300K. Such a favourable effect is due to the Ca 2+-Ba 2+ cationic substitution. These new compositions are of interest for applications (dielectric for capacitors, actuators) in the way of environmental protection.

Ravez, J.; Simon, A.

1999-01-01

29

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

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

30

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

31

Relaxor-based ferroelectric single crystals for electromechanical 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 (PZT's), morphotropic phase boundary compositions were not essential for high piezoelectric strain. Piezoelectric coefficients (d33's) > 2500 pC\\/N and subsequent strain levels up to > 0.6%

Seung Eek Park; Venkata Vedula; Ming Jen Pan; Wesley S. Hackenberger; Patrick Pertsch; Thomas R. Shrout

1998-01-01

32

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

33

Nanoscale Structure and the Two-timescale Dynamics of Relaxor Ferroelectrics  

NASA Astrophysics Data System (ADS)

The structural basis for the original dynamics of relaxor ferroelectrics lies in the development of mesoscopic or intermediate range order, the polar nanoregions (PNR). The formation of these PNRs can itself be related to the atomic site disorder that is characteristic of ferroelectric relaxors. For example, in KTa1-xNbxO3 (KTN), the niobium ions are off-centered in a [111] direction, and in PbMg1/3Nb2/3O3 (PMN) both Nb and Pb are off-centered, the latter in either a [110] or a [111] direction. These off-center ions can hop or tunnel between different symmetry-related positions and, with decreasing temperature, their motion can become correlated. In PMN, it is obvious that the hopping times of Pb and Nb will be very different because of the large difference in their masses as well as in their off-centering distances. It should therefore not be surprising to observe dynamics on two different timescales, and possibly also on two different length scales, simultaneously. This has a decisive influence on the physical properties of these systems, which are no longer simply a statistical average of the microscopic properties, but are determined at the mesoscopic level. A variety of experimental results suggest the existence of a two-timescale dynamics, which appears to be characteristic of the relaxor behavior. In this talk, we present a selection of the most meaningful results that support this assumption in several relaxor systems (KTN, PMN, PZN): these include Raman and neutron scattering, NMR, dielectric and ultrasonic results. We describe the evolution of the nanoscale structure with temperature and the corresponding evolution of the relaxor dynamics. We show that this evolution is characterized by four stages, a purely dynamic stage, a quasi-dynamic stage, a quasi-static stage and a static or frozen stage, which are also apparent in the macroscopic properties of relaxors. Finally, we point to intriguing similarities between the dynamics of relaxors and that of structural glasses.

Toulouse, Jean

2005-03-01

34

Relaxor and incipient ferroelectric phases in 6.5\\/65\\/35 PLZT ceramics  

Microsoft Academic Search

The linear and third harmonic nonlinear dielectric constants were measured in 6.5\\/65\\/35 PLZT hot-pressed ceramics. Linear dielectric data obtained on ooling show the transition from an ergodic to a nonergodic relaxor phase while, on heating, a ferroelectric to ergodic relaxor phase transition appears. The third harmonic di-electric response is reminiscent of an ergodic to nonergodic relaxor phase transition. Existence of

C. Filipi?; B. Vodopivec; J. Holc; A. Levstik; Z. Kutnjak; H. Beige

2004-01-01

35

Dielectric properties of partially disordered lanthanum-modified lead zirconate titanate relaxor ferroelectrics  

Microsoft Academic Search

Linear and third-order nonlinear dielectric susceptibilities and the dielectric polarization were measured in 6.5\\/65\\/35 lanthanum lead zirconate titanate (PLZT) hot-pressed ceramics. On cooling linear dielectric data show a transition from an ergodic to a nonergodic relaxor phase, while, on heating, a ferroelectric to ergodic relaxor phase transition appears. The third-order dielectric response is reminiscent of an ergodic to nonergodic relaxor

Boris Vodopivec; Cene Filipic; Adrijan Levstik; Janez Holc; Zdravko Kutnjak; Horst Beige

2004-01-01

36

Temperature dependence of flexoelectric response in ferroelectric and relaxor polymer thin films  

NASA Astrophysics Data System (ADS)

We report the temperature dependence of the flexoelectric response in thin films of both ferroelectric and relaxor forms of vinylidene fluoride polymers. The ferroelectric samples were depoled to minimize piezoelectric response by heating them beyond their Curie temperature and then cooling in zero applied electric field. In both the relaxor ferroelectric polymer and the paraelectric state of the ferroelectric copolymer, the flexoelectric coefficient was proportional to the dielectric constant over a limited range of temperatures, in agreement with general theoretical principles. The enhancements in flexoelectric response were also observed near the Curie transition temperature for the ferroelectric polymer and near the dielectric relaxation temperature for the relaxors. The broad dielectric anomaly in these systems provides greater temperature stability for these enhancements.

Poddar, Shashi; Ducharme, Stephen

2014-09-01

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

Coupled spherical pseudospin-phonon model and the pressure-temperature phase diagram of relaxor ferroelectrics  

E-print Network

,3 The parent perovskite compounds of re- laxor materials are typical monodispersive soft-mode ferro- electrics- mal ferroelectrics, relaxors show a strong frequency disper- sion of the dielectic properties into a ferroelectric phase by the application of an electric field exceeding a critical value Ec . Hydrostatic pressure

Pirc, Rasa

39

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

E-print Network

Electric-field­temperature phase diagram of the relaxor ferroelectric lanthanum-modified lead in the electric-field­temperature phase diagram of 9/65/35 lanthanum-modified lead zirconate titanate ceramics ferroelectrics. S0163-1829 99 00233-7 I. INTRODUCTION Lanthanum-modified lead zirconate titanate ceramics Pb1 x

Bobnar, Vid

40

FAST TRACK COMMUNICATION: Magnetic field induced ferroelectric to relaxor crossover in Tb1-xCaxMnO3  

NASA Astrophysics Data System (ADS)

The influence of magnetic field on the electrical properties of Tb1-xCaxMnO3 has been investigated by means of dielectric, polarization and neutron diffraction measurements. A field of 6 T applied along the b-axis induces a crossover from ferroelectric to relaxor behavior for the x = 0.02 compound at temperatures close to the ferroelectric transition. The mechanism of this field induced crossover involves a decrease in the coherence length of the Mn-spin-spiral structure due to increasing electron hopping rates associated with double exchange. Moreover, a large negative magnetocapacitance is observed at the freezing temperature for x = 0.05, which originates from suppression of the relaxor state and thus represents a new mechanism of magnetocapacitance.

Mufti, N.; Blake, G. R.; Nugroho, A. A.; Palstra, T. T. M.

2009-11-01

41

Dielectric relaxation behavior in barium stannate titanate ferroelectric ceramics with diffused phase transition  

NASA Astrophysics Data System (ADS)

The temperature dependence of dielectric permittivity was investigated for two ferroelectric ceramic compositions in a barium stannate titanate solid solution system. The dielectric relaxation behavior was observed in these ferroelectrics with diffused phase transition. In view of the polar nanoregion, the relationship between relaxor ferroelectric and ferroelectrics with a diffused phase transition was explored. The results suggest that, in barium stannate titanate, the relaxor ferroelectric dielectric behavior is universal in the diffused phase transition region, but it only appears when the experimental frequency is close to the relaxation frequency of polar nanoregion at that temperature.

Xiaoyong, Wei; Yujun, Feng; Xi, Yao

2003-09-01

42

Scattering of the Transverse Acoustic Phonon by Polar Nanodomains in the Relaxor Ferroelectric KTa1-xNbxO3 (KTN)  

Microsoft Academic Search

We show that, in relaxors, the transverse acoustic (TA) mode displays a particularly original behavior, due its coupling to the transverse optic (TO) mode as well as to the polarization P of the Polar Nano-Domains (PND) that are ubiquitous in these special ferroelectrics. A neutron scattering study of the TA phonon frequency and damping, and especially of their q dependence,

Jean Toulouse; Eugene Iolin; Bernard Hennion; Daniel Petitgrand; Ross Erwin

2009-01-01

43

High-temperature dielectric response of ferroelectric relaxors.  

PubMed

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

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

2011-11-01

44

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

45

NMR and the spherical random bond–random field model of relaxor ferroelectrics  

Microsoft Academic Search

To determine the nature of the relaxor state and, in particular, to discriminate between a ferroelectric state broken up into nanodomains under the constraint of quenched random fields and a glassy state we have measured the temperature dependences of the nonlinear dielectric susceptibility in zero field as well as the temperature dependence of the local polarization distribution function and the

R. Blinc; J Dolinšek; A Gregorovi?; B Zalar; C Filipi?; Z Kutnjak; A Levstik; R Pirc

2000-01-01

46

Phase instability induced by polar nanoregions in a relaxor ferroelectric system  

NASA Astrophysics Data System (ADS)

Relaxor ferroelectrics are a special class of material that exhibit an enormous electromechanical response and are easily polarized with an external field. These properties make them attractive for applications as sensors and actuators. Local clusters of randomly oriented polarization, known as polar nanoregions (PNRs), are specific to relaxor ferroelectrics and play a key role in governing their dielectric properties. Here, we show through neutron inelastic scattering experiments that the PNRs can also significantly affect the structural properties of the relaxor ferroelectric Pb(Zn1/3Nb2/3)O3-4.5%PbTiO3 (PZN-4.5%PT). A strong interaction is found between the PNRs and the propagation of acoustic phonons. A comparison between acoustic phonons propagating along different directions reveals a large asymmetry in the lattice dynamics that is induced by the PNRs. We suggest that a phase instability induced by this PNR-phonon interaction may contribute to the ultrahigh piezoelectric response of this and related relaxor ferroelectric materials. Our results naturally explain the emergence of the various observed monoclinic phases in these systems.

Xu, Guangyong; Wen, Jinsheng; Stock, C.; Gehring, P. M.

2008-07-01

47

Ferroelectric-to-Relaxor Crossover and Oxygen Vacancy Hopping in Compositionally-Disordered Perovskites - KtA(1-x)Nb(x)O(3):Ca  

SciTech Connect

It is shown that lattice disorder induced by Nb and Ca substitution has a strong influence on the dielectric and relaxational properties of KTaO{sub 3}. Both substituents are believed to occupy off-center positions at the Ta site, and the difference in valence between the Ca{sup 2+} and Ta{sup 5+} ions leads to the formation of oxygen vacancies (V{sub 0}). Specifically, for a KTa{sub 1{minus}x}Nb{sub x}O{sub 3}:Ca crystal with x = 0.023 and with a 0.055 at.% Ca doping they observe: (1) a ferroelectric transition at atmospheric pressure (1 bar); (2) a large enhancement of the transition temperature by Ca doping; (3) a pressure-induced crossover from ferroelectric-to-relaxor behavior; (4) the impending vanishing of the relaxor phase at high pressure; (5) the reorientation of the Ca-oxygen vacancy (Ca:V{sub 0}) pair defect; and (6) the variation of the energetics and dynamics of this reorientation with pressure. Most of these effects are associated with Nb- and Ca-induced dipolar entities and appear to be general features of soft mode ferroelectrics with random-site polar nanodomains. The ferroelectric-to-relaxor crossover can be understood in terms of a large decrease with pressure in the correlation length among polar nanodomains--a unique property of soft ferroelectric mode systems.

Samara, G.A.; Boatner, L.A.

1999-07-26

48

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

49

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

SciTech Connect

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

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

2013-12-23

50

Far-infrared and dielectric spectroscopy of relaxor ferroelectric (Pb1-xLax)(Zr0.4Ti0.6)O3  

Microsoft Academic Search

The dielectric behavior of tetragonal (Pb1-xLax)(Zr0.4Ti0.6)O3 (PLZT x\\/40\\/60) ceramics doped with lanthanum (x=12% and 15%) has been investigated from 102 to 1014 Hz in the temperature range of 20-800 K. Relaxor ferroelectric behavior, together with a first-order ferroelectric phase transition at TC below the dielectric maximum, was revealed. The lowest-frequency phonon partially softens to TC and splits into two components

E. Buixaderas; D. Nuzhnyy; S. Veljko; S. Kamba; M. Savinov; J. Petzelt; M. Kosec

2007-01-01

51

Scattering of the Transverse Acoustic Phonon by Polar Nanodomains in the Relaxor Ferroelectric KTa1-xNbxO3 (KTN)  

NASA Astrophysics Data System (ADS)

We show that, in relaxors, the transverse acoustic (TA) mode displays a particularly original behavior, due its coupling to the transverse optic (TO) mode as well as to the polarization P of the Polar Nano-Domains (PND) that are ubiquitous in these special ferroelectrics. A neutron scattering study of the TA phonon frequency and damping, and especially of their q dependence, reveals that the PNDs condense in the form of platelets. In the relaxor range of temperatures, in which elastic diffuse scattering is also observed, the TA mode is strongly scattered by the PNDs. We compare our results with those from thermal conductivity studies of inhomogenous solids and similar neutron results obtained in other perovskite systems. We also present a theoretical model that describes the scattering mechanism specific to relaxors, the TA-P-TO interaction, is shown to fit the acoustic data well and also provides an estimate of the TO mode frequency and damping.

Toulouse, Jean; Iolin, Eugene; Hennion, Bernard; Petitgrand, Daniel; Erwin, Ross

2009-03-01

52

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

NASA Astrophysics Data System (ADS)

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

Zhang, Shujun; Li, Fei

2012-02-01

53

Nanoscopic Study of the Polarization-Strain Coupling in Relaxor Ferroelectric and the Search for New Relaxor Materials for Transducer and Optical Applications  

SciTech Connect

SUMMARY Relaxor ferroelectrics exhibit a very unusual polarization behavior from which derive unique electrostrictive, piezoelectric and other properties. This behavior and these properties are due to the presence of nanoscale structural and polar order, the polar nanoregions (PNR), which can easily reorient under very modest external electric field, in stark contrast with conventional ferroelectrics. Moreover, when these nanoregions are aligned, their local distortions add up coherently to a macroscopic strain, hence their remarkable electrostrictive and piezoelectric properties. Initially, we demonstrated this effect in KTa1-xNbxO3 (KTN) and were able to identify the local internal symmetry of the PNR in KTN and explain their behavior under an applied electric field. We then extended the study to the more complicated lead relaxors, PbMg1/3Nb2/3O3 (PMN), PbZn1/3Nb2/3O3 (PZN) and (1-x)(PbZn1/3Nb2/3)O3-(x)PbTiO3 (PZN-PT). In particular, following the evolution of the diffuse intensity in neutron scattering and X-ray measurements, we were able to determine the evolution of the polar order from the pure PZN system to the mixed system, PZN-PT. This evolution with addition of PT, provides a physical basis for the remarkably easy polarization rotation that gives PZN-PT its unique properties for composition near the so-called morphotropic boundary (MPB). Through quasi-elastic and inelastic neutron and Raman scattering, we also obtained information about the local (nano)dynamics of these PNR’s. We thus identified three ranges in the evolution of the polarization with temperature: a purely dynamic range, a quasi-dynamic range when the PNR’s appear but can still reorient as “giant dipoles”, a quasi-static range when the system undergoes a series of “underlying” or partial transitions (on a mesoscopic scale) and, finally a frozen range below the last one of these transitions”. This work has provided a useful framework to describe the structural and temperature evolution from the nanoscopic to the mesoscopic polar order and even to a macroscopic polar order in the presence of an applied electric field. The results of this study also provide a physical model to explain the very strong polarization-strain coupling in these relaxors.

J. Toulouse

2007-05-31

54

Relaxor freezing and electric-field induced ferroelectric transition in a lanthanum lead zirconate titanate ceramics  

Microsoft Academic Search

Transition lines between various phases in the electric-field temperature phase diagram of 9\\/65\\/35 lanthanum lead zirconate titanate ceramics were determined by measurements of the temperature and electric-field dependent dielectric constant. Above the critical field (EC) the dc bias electric field induces a transition from the relaxor to the ferroelectric phase, while below EC the system exhibits a freezing transition between

V. Bobnar; Z. Kutnjak; R. Pirc; A. Levstik

1999-01-01

55

Electric-field-temperature phase diagram of the relaxor ferroelectric lanthanum-modified lead zirconate titanate  

Microsoft Academic Search

Transition lines between various phases in the electric-field-temperature phase diagram of 9\\/65\\/35 lanthanum-modified lead zirconate titanate ceramics were determined by measurements of the temperature and electric-field-dependent dielectric constant. Above a critical field (EC) the dc bias electric field induces a transition from the relaxor (R) to the long-range ferroelectric (FE) phase. In the temperature direction of the approach to the

Vid Bobnar; Zdravko Kutnjak; Rasa. Pirc; Adrijan Levstik

1999-01-01

56

Relaxor Ferroelectric Polymers, Thin Film Devices, and Ink-Jet Microprinting for Thin Film Device Fabrication  

Microsoft Academic Search

The relaxor ferroelectric polymer, based on poly(vinylidene fluoride-trifluoroethylene- chlorofluoroethylene) (P(VDF-TrFE-CFE)) terpolymer, exhibits high electromechanical response and dielectric response, suitable for a wide range of army applications such as micro-actuators, high efficiency pulse power capacitors, and solid state cooling devices. Recent experimental results show that with a simple blends approach, the terpolymer glass transition temperature can be raised quite markedly, resulting

Shihai Zhang; Bret Neese; Kailiang Ren; Baojin Chu; Feng Xia; T. Xu; Srinivas Tadigadapa; Qing Wang; Q. M. Zhang; F. Bauer

2006-01-01

57

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

SciTech Connect

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

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

2005-05-16

58

Random local strain e#ects in homovalentsubstituted relaxor ferroelectrics: a firstprinciples study of BaTi 0.74 Zr 0.26 O 3  

E-print Network

present first­principles supercell calculations on BaTi0.74 Zr0.26 O3 , a prototype material for relaxors relaxors with homovalent substitution. PACS numbers: Keywords: The understanding of ferroelectric materials fundamental and application­related issues. 1 Among ferroelectrics, re­ laxors form a fascinating class

Recanati, Catherine

59

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

SciTech Connect

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

SAMARA,GEORGE A.

2000-02-14

60

Dynamic Polar Nanoregions and Broken Local Symmetry in Relaxor Ferroelectrics Probed by Inelastic Light Scattering  

NASA Astrophysics Data System (ADS)

The precursor dynamics of relaxor ferroelectrics are studied by Brillouin and Raman scattering. Above TC, Raman scattering spectra reflect the existence of polar nanoregions (PNRs) by broken local symmetry in a cubic matrix. The polarization fluctuations in dynamic PNRs induce elastic anomaly and an intense broad central peak below Burns temperature TB. The average size of dynamic PNRs was estimated as a function of temperature assuming the local piezoelectricity in PNRs owing to the lack of the center of symmetry. The marked growth of the size towards TC was found in a cubic paraelectric phase. In normal ferroelctric KTN, BaTiO3 also show the precursor dynamics related to dynamic PNRs.

Kojima, Seiji; Ohta, Ryu; Ariizumi, Takuma; Zushi, Junta

2013-04-01

61

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

Microsoft Academic Search

Solid solutions of (1-x)Pb(Mg1\\/3Nb2\\/3)O3xPb(Sc1\\/2Nb1\\/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

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

2004-01-01

62

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

63

On a mathematical model for polycrystalline ferroelectrics - relaxors  

NASA Astrophysics Data System (ADS)

A mathematical model of the process of polarization and depolarization ferroelectric polycrystalline materials in intensive electric and mechanical fields was presented. In the foundation of the our theory was laid the model of locked walls, where been introduced the submission of limited maximum of possible polarization in the representative volume, based on Boltzman's statistical law and the ratio of balance of an energy, allowing one consider the influence of neighboring domains in the process of switching. This model contains two principal new approach, which not been used previously. First, we enter a density function of distribution domains, allowing defining the resulting polarization and deformation of representative volume in the limiting case. Second, we introduce the energy criterion of switching domains, allowing generalizing the model of locked walls on a case of simultaneous exposure the electric and mechanical fields. All studies were conducted in the three-dimensional case. The built model is represent the constitutive relations of an irreversible process of polarization in the differential form and can be used for finite element analysis of the nonlinear processes of polarization and depolarization polycrystalline ferroelectrics.

Skaliukh, A. S.

2014-11-01

64

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

65

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

PubMed

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

Sun, Enwei; Cao, Wenwu

2014-08-01

66

Direct spectroscopic evidence of field-induced solid-state chain conformation transformation in a ferroelectric relaxor polymer  

Microsoft Academic Search

Ferroelectric relaxor P(VDF-TrFE-CFE) terpolymer can generate a hysteresis-free polarization of 47 mC\\/m2 at an electric field of 100 MV\\/m and is attractive for many potential actuating and sensing applications. Fourier transform infrared spectra under electric field reveal that this large polarization originates from the field-induced crystalline phase transformation. The nonpolar TGTG' chain conformation in P(VDF-TrFE-CFE) can be converted into polar

Shihai Zhang; Baojin Chu; Bret Neese; Kailiang Ren; Xin Zhou; Q. M. Zhang

2006-01-01

67

Coexistence and competition of local- and long-range polar orders in a ferroelectric relaxor  

SciTech Connect

We have performed a series of neutron diffuse scattering measurements on a single crystal of the solid solution Pb(Zn{sub 1/3}Nb{sub 2/3})O{sub 3} doped with 8% PbTiO{sub 3}, a relaxor compound with a Curie temperature T{sub C}{approx}450 K, in an effort to study changes in local polar orders associated with the polar nanoregions (PNR) when the material enters the ferroelectric phase. The diffuse scattering intensity increases monotonically upon cooling in zero field, but the rate of increase varies dramatically around different Bragg peaks. These results can be explained by assuming that corresponding changes occur in the ratio of the optic and acoustic components of the atomic displacements within the PNR. Cooling in the presence of a modest electric field E(vector sign) oriented along the [111] direction alters the shape of diffuse scattering in reciprocal space, but does not eliminate the scattering as would be expected in the case of a classic ferroelectric material. This suggests that a field-induced redistribution of the PNR has taken place.

Xu Guangyong [Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973 (United States); Gehring, P. M. [NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); Shirane, G. [Physics Department, Brookhaven National Laboratory, Upton, New York 11973 (United States)

2006-09-01

68

Polarization-based perturbations to thermopower and electronic conductivity in highly conductive tungsten bronze structured (Sr,Ba)Nb2O6: Relaxors vs normal ferroelectrics  

NASA Astrophysics Data System (ADS)

Electrical conductivity, thermopower, and lattice strain were investigated in the tetragonal tungsten bronze structured (Srx,Ba1-x)Nb2O6-? system for 0.7>x>0.4 with large values of ?. These materials show attractive thermoelectric characteristics, especially in single-crystal form. Here, the Sr/Ba ratio was changed in order to vary the material between a normal ferroelectric with long-range polarization to relaxor behavior with short-range order and dynamic polarization. The influence of this on the electrical conduction mechanisms was then investigated. The temperature dependence of both the thermopower and differential activation energy for conduction suggests that the electronic conduction is controlled by an impurity band with a mobility edge separating localized and delocalized states. Conduction is controlled via hopping at low temperatures, and as temperature rises electrons are activated above the mobility edge, resulting in a large increase in electrical conductivity. For relaxor ferroelectric-based compositions, when dynamic short-range order polarization is present in the system, trends in the differential activation energy and thermopower show deviations from this conduction mechanism. The results are consistent with the polarization acting as a source of disorder that affects the location of the mobility edge and, therefore, the activation energy for conduction.

Bock, Jonathan A.; Trolier-McKinstry, Susan; Mahan, Gerald D.; Randall, Clive A.

2014-09-01

69

Coexistence of the critical slowing down and glassy freezing in relaxor ferroelectrics  

NASA Astrophysics Data System (ADS)

We have developed a dynamical model for the dielectric response in relaxor ferroelectrics that explicitly takes into account the coexistence of the critical slowing down and glassy freezing. The application of the model to the experiment in PbMg1/3Nb2/3O3 (PMN) allowed for the reconstruction of the nonequilibrium spin-glass state order parameter and its comparison with the results of recent NMR experiment [R. Blinc et al., Phys. Rev. Lett 83, 424 (1999)]. It is shown that the degree of the local freezing is rather small even at temperatures where the field-cooled permittivity exceeds the frequency-dependent permittivity by an order of magnitude. This observation indicates the significant role of the critical slowing down (accompanying the glass freezing) in the system dynamics. Also, the theory predicts an important interrelationship between the frequency-dependent permittivity and the zero-field-cooled permittivity, which proved to be consistent with the experiment in PMN [A. Levstik et al., Phys. Rev. B 57, 11 204 (1998)].

Vugmeister, B. E.; Rabitz, H.

2000-06-01

70

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

NASA Astrophysics Data System (ADS)

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

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

2012-05-01

71

Direct spectroscopic evidence of field-induced solid-state chain conformation transformation in a ferroelectric relaxor polymer  

NASA Astrophysics Data System (ADS)

Ferroelectric relaxor P(VDF-TrFE-CFE) terpolymer can generate a hysteresis-free polarization of 47 mC/m2 at an electric field of 100 MV/m and is attractive for many potential actuating and sensing applications. Fourier transform infrared spectra under electric field reveal that this large polarization originates from the field-induced crystalline phase transformation. The nonpolar TGTG' chain conformation in P(VDF-TrFE-CFE) can be converted into polar trans (Tm>4 and T3G) conformation under high electric field and the latter can be effectively aligned to the applied field direction. Furthermore, this conformation transformation is completely reversible and no hysteresis can be observed during the switching of applied electric field. In contrast, normal ferroelectric polymer P(VDF-TrFE) exhibits square polarization loop with very small reversible polarization.

Zhang, Shihai; Chu, Baojin; Neese, Bret; Ren, Kailiang; Zhou, Xin; Zhang, Q. M.

2006-02-01

72

Crossover from Glassy to Inhomogeneous-Ferroelectric Nonlinear Dielectric Response in Relaxor Ferroelectrics  

Microsoft Academic Search

The temperature dependence of the dielectric nonlinearities in a PMN single crystal and in 9\\/65\\/35 PLZT ceramics has been determined by measuring the first and third harmonic response as well as the dielectric behavior as a function of the dc electric field. In zero field a paraelectric-to-glass, and, in a high enough dc field, a glass-to-ferroelectriclike crossover in the temperature

Vid Bobnar; Zdravko Kutnjak; Robert Blinc; Adrijan Levstik

2000-01-01

73

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

74

Lead-free ferroelectric relaxor ceramics derived from BaTiO_3  

NASA Astrophysics Data System (ADS)

A large number of lead-free BaTiO3-based ceramics were prepared. Depending on the composition, some of them exhibit a relaxor behaviour whose characteristics were related to the type of ionic substitution and to the substitution rate. The relaxor effect is all the more favoured as the composition deviates more from BaTiO3 and as the substitution is heterovalent in the 6-coordination number crystallographic site. Some of these materials could prove valuable (dielectrics for capacitors and actuators) because they are environment-friendly.

Ravez, J.; Simon, A.

2000-07-01

75

Non-linear dielectric properties in based-PMN relaxor ferroelectrics  

Microsoft Academic Search

The investigation of the non-linear dielectric response in ferroelectric materials has become one of the most important issues in the field of ferroelectricity due to its technological and scientific interest. Rather, from the practical point of view the understanding of the non-linear dielectric properties is essential to improve the performance of ferroelectric multilayer capacitors and actuators devices, which commonly operate

J. de Los S. Guerra; M. H. Lente; J. A. Eiras

2007-01-01

76

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

77

25 pyrochlore relaxor ferroelectric Cd2Nb2O7 and its Fe2  

E-print Network

, and possible applications of the materials in electronics due to strong sensitivity of their physical and glassy properties of the system. It is revealed that Cd2Nb2O7 pyrochlore is intolerant of the addition.1063/1.1415540 I. INTRODUCTION In past decades, studies of the perovskite relaxor ferro- electrics like PbMg1/3Nb2

Paris-Sud XI, Université de

78

High pressure Raman spectroscopic study on the relaxor ferroelectric PbSc(0.5)Nb(0.5)O(3).  

PubMed

The pressure evolution of the local structure and dynamics of polar nanoregions in PbSc(0.5)Nb(0.5)O(3) relaxor ferroelectric is analysed by Raman spectroscopy. The pressure dependence of phonon modes up to 10 GPa reveals three characteristic pressures related to changes in the local structure: near 2 GPa, at which ferroic ordering in the Pb system occurs; near 4 GPa, at which significant structural transformations, involving decoupling of Pb and B-cations in polar nanoclusters and suppression of the B-cation off-centring take place; and near 6 GPa, at which the system reaches a saturation state. The structural transformations observed in PbSc(0.5)Nb(0.5)O(3) are compared to those in PbSc(0.5)Ta(0.5)O(3) and other Pb-based perovskite-type relaxor ferroelectrics. PMID:21825597

Welsch, A-M; Mihailova, B; Gospodinov, M; Stosch, R; Güttler, B; Bismayer, U

2009-06-10

79

Change in the Dielectric Properties of Normal and Relaxor Ferroelectric Ceramic Composites in BT-PZT and PMN-PZT Systems by an Uniaxial Compressive Stress  

Microsoft Academic Search

Effects of an uniaxial compressive pre-stress on the dielectric properties of normal and relaxor ferroelectric ceramic composites in BT-PZT and PMN-PZT systems are investigated. The dielectric properties are observed under the compressive pre-stress levels up to 15 and 5 MPa for BT-PZT and PMN-PZT, respectively, using a uniaxial compressometer. Both the dielectric constant and the dielectric loss tangent of the

Rattikorn Yimnirun

2006-01-01

80

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

81

Evolution of structure, dielectric properties, and re-entrant relaxor behavior in Ba5LaxSm1-xTi3Nb7O30 (x = 0.1, 0.25, 0.5) tungsten bronze ceramics  

NASA Astrophysics Data System (ADS)

The effects of A site occupation on the structure, dielectric, and re-entrant relaxor behaviors were studied for Ba5LaxSm1-xTi3Nb7O30 (x = 0.1, 0.25, 0.5) tungsten bronze ceramics. The tetragonal tungsten bronze structure in space group P4bm was indicated for all compositions. The dielectric and ferroelectric properties were investigated over a broad temperature range. For all compositions, broad permittivity peaks with strong frequency dispersion were observed, where the peak points well fitted the Vogel-Fulcher relationship. The temperature dependency of ferroelectric hysteresis loops indicated the re-entrant relaxor behavior for all compositions: both the maximum and remanent polarization tended to decrease and vanish at low temperatures. In Ba5LaxSm1-xTi3Nb7O30, the re-entrant temperature (Tr) decreased with La-substitution, and the reduced remanent polarization at Tr (PTr) was determined. It seemed that the A1 site cation substitution exerted direct effects on the long-range ferroelectric order, and then the re-entrant relaxor behavior.

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

2013-07-01

82

Local Polarization Distribution and Edwards-Anderson Order Parameter of Relaxor Ferroelectrics  

Microsoft Academic Search

The temperature dependence of the Edwards-Anderson order parameter qEA and the local polarization distribution function W\\\\(p-->\\\\) have been determined in a PMN single crystal via 2D 93Nb NMR. A glasslike freezing of reorientable polar clusters occurs in the temperature range of the diffuse relaxor transition, whereas the NMR spectra corresponding to pinned nanodomains do not change with temperature. The obtained

R. Blinc; J. Dolins Ek; A. Gregorovic; B. Zalar; C. Filipic; Z. Kutnjak; A. Levstik; R. Pirc

1999-01-01

83

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

SciTech Connect

The effect of heterovalent B-site doping on ergodicity of relaxor ferroelectrics is studied using (1???y)(0.81Bi{sub 1/2}Na{sub 1/2}TiO{sub 3}-0.19Bi{sub 1/2}K{sub 1/2}TiO{sub 3})-yBiZn{sub 1/2}Ti{sub 1/2}O{sub 3} (BNT-BKT-BZT) with y?=?(0.02;0.03;0.04) as a model system. Both the large- and small-signal parameters are studied as a function of electric field. The crystal structure is assessed by means of neutron diffraction in the initial state and after exposure to a high electric field. In order to measure ferroelastic domain textures, diffraction patterns of the poled samples are collected as a function of sample rotation angle. Piezoresponse force microscopy (PFM) is employed to probe the microstructure for polar regions at a nanoscopic scale. For low electric fields E?behavior do not change with composition. At high electric fields, however, drastic differences are observed due to a field-induced phase transition into a long-range ordered state. It is hypothesized that increasing BZT content decreases the degree of non-ergodicity; thus, the formation of long-range order is impeded. It is suggested that frozen and dynamic polar nano regions exist to a different degree, depending on the BZT content. This image is supported by PFM measurements. Moreover, PFM measurements suggest that the relaxation mechanism after removal of the bias field is influenced by surface charges.

Dittmer, Robert; Jo, Wook, E-mail: jo@ceramics.tu-darmstadt.de; Rödel, Jürgen [Institute of Materials Science, Technische Universität Darmstadt, Petersenstraße 23, 64287 Darmstadt (Germany); Gobeljic, Danka; Shvartsman, Vladimir V.; Lupascu, Doru C. [Institute for Material Science and Center for Nanointegration Duisburg-Essen (CeNIDE), University of Duisburg-Essen, Universitätsstraße 15, 45141 Essen (Germany); Jones, Jacob L. [Department of Materials Science and Engineering, University of Florida, Gainesville, Florida 32611-6400 (United States); Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States)

2014-02-28

84

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

85

Enhanced dielectric constant and relaxor behavior realized by dual stage sintering of Sr{sub 0.5}Ba{sub 0.5}Nb{sub 2}O{sub 6}  

SciTech Connect

The relaxor ferroelectric compound, Sr{sub 0.5}Ba{sub 0.5}Nb{sub 2}O{sub 6} (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., E-mail: satish.vitta@iitb.ac.in; Vitta, Satish, E-mail: satish.vitta@iitb.ac.in [Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay, Mumbai- 400076 (India)

2014-04-24

86

Nanoscale phase quantification in lead-free (Bi1 /2Na1 /2) TiO3-BaTiO3 relaxor ferroelectrics by means of 23Na NMR  

NASA Astrophysics Data System (ADS)

We address the unsolved question on the structure of relaxor ferroelectrics at the atomic level by characterizing lead-free piezoceramic solid solutions (100 -x ) (Bi1 /2Na1 /2) TiO3-x BaTiO3 (BNT -x BT ) (for x =1 ,4 ,6 , and 15). Based on the relative intensity between spectral components in quadrupolar perturbed 23Na nuclear magnetic resonance, we present direct evidence of the coexistence of cubic and polar local symmetries in these relaxor ferroelectrics. In addition, we demonstrate how the cubic phase vanishes whenever a ferroelectric state is induced, either by field cooling or changing the dopant amount, supporting the relation between this cubic phase and the relaxor state.

Groszewicz, Pedro B.; Breitzke, Hergen; Dittmer, Robert; Sapper, Eva; Jo, Wook; Buntkowsky, Gerd; Rödel, Jürgen

2014-12-01

87

Re-entrant relaxor behavior of Ba5RTi3Nb7O30 (R = La, Nd, Sm) tungsten bronze ceramics  

NASA Astrophysics Data System (ADS)

Ba5RTi3Nb7O30 (R = La, Nd, Sm) tungsten bronze ceramics were prepared, and the dielectric and ferroelectric properties were investigated over a broad temperature range. The relaxor nature was determined for all compositions in their permittivity curves, and a second anomaly of the dielectric loss (tan ?) was observed around 250 K in Ba5NdTi3Nb7O30 and around 275 K in Ba5SmTi3Nb7O30. Both the maximum and remanent polarization tended to decrease and vanish at low temperatures in the ferroelectric phase for all compositions, which was referred to as the low temperature re-entrant relaxor behavior. The remanent polarization increased with decreasing temperature first and then reached the maximum value at the re-entrant temperature (Tr). For Ba5RTi3Nb7O30 (R = La, Nd, Sm), Tr decreased with the radius of R3+ cations and the applied field amplitude.

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

2013-03-01

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

Chemically induced renormalization phenomena in Pb-based relaxor ferroelectrics under high pressure  

NASA Astrophysics Data System (ADS)

The pressure-induced phase transition sequence in PbSc0.5Ta0.5O3 (PST) and PbSc0.5Nb0.5O3 (PSN) heavily doped with homo- and heterovalent cations on the A- or B-site of the perovskite-type structure (ABO3) was analysed by in situ synchrotron x-ray diffraction and Raman spectroscopy up to pressures of 25 GPa. We focused on the structural phenomena occurring above the first pressure-induced phase transition at pc1 from a relaxor state to a non-polar rhombohedral phase with antiphase tilting of the BO6 octahedra. The samples studied were PST doped with Nb5+ and Sn4+ on the B-site, PST doped with Ba2+ and La3+ on the A-site and PSN doped with Sr2+ and La3+ on the A-site. All of them exhibit a second pressure-induced phase transition at pc2, similar to pure PST and PSN. The second transition involves the development of either order of antiparallel Pb2+ displacements and complementary a+b-b- octahedral tilts, or a-b-b- (0 ? a < b) tilting alone. As in pure PST and PSN, the second phase transition is preceded by the occurrence of unequal octahedral tilts on the local scale. The substitution of Nb5+ for Ta5+ as well as the coupled substitution of Sn4+ for Sc3+ + Ta5+ on the octahedral B sites increases the second critical pressure. The doping by Nb5+ also reduces the length of coherence of antipolar Pb2+ order developed at pc2. The isovalent substitution of the larger Ba2+ for Pb2+ on the A-site suppresses the antipolar Pb2+ order due to the induced local elastic stresses and thus significantly increases pc2. The substitution of smaller cations for Pb2+ on the A-site generally favours the development of long-range order of antiparallel Pb2+ displacements because of the chemically enhanced a-a-a- octahedral tilts. However, this ordering is less when the dopant is aliovalent, due to the charge imbalance on the A-site. For all of the relaxors studied here, the dynamic compressibility estimated from the pressure derivative of the wavenumber of the soft mode associated with the first phase transition is larger in the pressure interval between pc1 and pc2 than above pc2. The dynamic compressibility of the phase above pc2 decreases if the antipolar Pb2+ order is disturbed.

Mihailova, B.; Waeselmann, N.; Maier, B. J.; Angel, R. J.; Prüßmann, T.; Paulmann, C.; Gospodinov, M.; Bismayer, U.

2013-03-01

90

Interplay between pressure and local symmetry in (Pb1 -3 /2 xLax)(Zr60Ti40)O3: Emergence of a relaxor state  

NASA Astrophysics Data System (ADS)

This study aims at inquiring into the role of hydrostatic pressure in driving the relaxor behavior within a local-symmetry-based approach to relaxor ferroelectrics. Results reveal the occurrence of a pressure-induced ferroelectric-to-relaxor crossover, clearly reflected in the experiment-matching temperature-pressure phase diagram of lanthanum-modified lead zirconate titanate. Relaxor behavior is found to occur under pressure and upon cooling due to the nucleation of local order within fractal regions, as an incipient state towards percolating ferroelectric order. Further analysis of the geometrical features of ordering process points to a manifest nontrivial disruption of the balance between competing interactions under the conjugated effects of pressure and local-symmetry constraints.

Nahas, Y.; Prokhorenko, S.; Kornev, I.

2014-11-01

91

Chemically induced renormalization phenomena in Pb-based relaxor ferroelectrics under high pressure.  

PubMed

The pressure-induced phase transition sequence in PbSc(0.5)Ta(0.5)O(3) (PST) and PbSc(0.5)Nb(0.5)O(3) (PSN) heavily doped with homo- and heterovalent cations on the A- or B-site of the perovskite-type structure (ABO(3)) was analysed by in situ synchrotron x-ray diffraction and Raman spectroscopy up to pressures of 25 GPa. We focused on the structural phenomena occurring above the first pressure-induced phase transition at p(c1) from a relaxor state to a non-polar rhombohedral phase with antiphase tilting of the BO(6) octahedra. The samples studied were PST doped with Nb(5+) and Sn(4+) on the B-site, PST doped with Ba(2+) and La(3+) on the A-site and PSN doped with Sr(2+) and La(3+) on the A-site. All of them exhibit a second pressure-induced phase transition at p(c2), similar to pure PST and PSN. The second transition involves the development of either order of antiparallel Pb(2+) displacements and complementary a(+)b(-)b(-) octahedral tilts, or a(-)b(-)b(-) (0 ? a < b) tilting alone. As in pure PST and PSN, the second phase transition is preceded by the occurrence of unequal octahedral tilts on the local scale. The substitution of Nb(5+) for Ta(5+) as well as the coupled substitution of Sn(4+) for Sc(3+) + Ta(5+) on the octahedral B sites increases the second critical pressure. The doping by Nb(5+) also reduces the length of coherence of antipolar Pb(2+) order developed at p(c2). The isovalent substitution of the larger Ba(2+) for Pb(2+) on the A-site suppresses the antipolar Pb(2+) order due to the induced local elastic stresses and thus significantly increases p(c2). The substitution of smaller cations for Pb(2+) on the A-site generally favours the development of long-range order of antiparallel Pb(2+) displacements because of the chemically enhanced a(-)a(-)a(-) octahedral tilts. However, this ordering is less when the dopant is aliovalent, due to the charge imbalance on the A-site. For all of the relaxors studied here, the dynamic compressibility estimated from the pressure derivative of the wavenumber of the soft mode associated with the first phase transition is larger in the pressure interval between p(c1) and p(c2) than above p(c2). The dynamic compressibility of the phase above p(c2) decreases if the antipolar Pb(2+) order is disturbed. PMID:23411463

Mihailova, B; Waeselmann, N; Maier, B J; Angel, R J; Prüßmann, T; Paulmann, C; Gospodinov, M; Bismayer, U

2013-03-20

92

Mesoscale constitutive behavior of ferroelectrics  

NASA Astrophysics Data System (ADS)

The main goal of this study is the in-situ investigation of the ferroelectric domain structure inside polycrystalline BaTiO3 under thermo-electro-mechanical loading conditions. The outcome is two-fold: (i) the characterization techniques were improved to study the polycrystalline ferroelectrics in the mesoscale; and (ii) the texture, lattice strain and volume fraction of domains were tracked under applied electric field and mechanical stress. Two novel synchrotron-based characterization techniques, three-dimensional X-ray diffraction (3-D XRD) and Scanning X-ray Microdiffraction (iSXRD) were used in this study. The methodology and standards in both techniques differ from each other and the present study provides a framework to bridge these techniques. Although these methods have been developed earlier, their application and adaptation to ferroelectrics required some care. For instance, diffraction spots often overlapped and made it difficult to identify individual domains and/or grains. In order to eliminate the spot overlap, the polycrystalline BaTiO3 sample was heated above the Curie temperature where the (tetragonal) domains disappear and attain the orientation of the grain. Next, the sample was cooled slowly to the room temperature and the evolution of the ferroelectric domains was studied at temperature and under electric field. The orientation relationships, volume fractions and lattice strain evolution of 8 domain systems were studied. Whereas the orientation of the domains remained unchanged under electric field, the fraction of the energetically favorable domain variants increased. Due to local constraints, complete switching from one domain variant to another was not observed. The misorientation angles between domain variants slightly deviated from the theoretical value (=89.4°) by 0.2-0.3°. The deviation angle can be explained with the phase-matching angle developed during the cubic-tetragonal phase transformation to maintain strain compatibility of neighboring domains. The multiscale strain evolution of ferroelectric domains in a polycrystal was investigated quantitatively for the first time. Under electric field, lattice strains of up to 0.1% were measured along the applied field direction. The present study offers a framework to characterize the polycrystalline materials with complex twin structures. By using the methodology described in this study, 3D-XRD and muSXRD techniques can be employed to study texture and lattice strain evolution in polycrystalline materials in the mesoscale.

Varlioglu, Mesut

93

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

94

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

PubMed

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

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

2015-01-01

95

Random-field Ising-type transition of pure and doped SBN from the relaxor into the ferroelectric state  

Microsoft Academic Search

Activated critical dynamics and vanishing of the susceptibility ratio a3 = chi3\\/chi14 --> 0 in the zero-frequency limit unequivocally evidence the phase transitions of the uniaxial relaxor crystals SBN, SBN:Ce and SBN:Cr to refer to the three-dimensional random-field Ising universality class. The relaxor-like freezing of polar nanoregions within the precursor regime is successfully described within the framework of the mesoscopic

J. Dec; W. Kleemann; V. Bobnar; Z. Kutnjak; A. Levstik; R. Pirc; R. Pankrath

2001-01-01

96

Chemical order and local structure of the lead-free relaxor ferroelectric NaBiTiO3  

NASA Astrophysics Data System (ADS)

The A-site mixed perovskite sodium bismuth titanate (NaBi)TiO3 (NBT) is investigated by means of first-principles calculations based on density functional theory. By studying different geometries with varying occupations of the A-site, the influence of chemical order on the thermodynamic stability and local structure is explored. We find that the hybridization of Bi 6 sp with O 2 p-states leads to stereochemically active Bi lone pairs and increases the stability of structures with high Bi concentrations in {001}-planes. This goes along with displacive disorder on the oxygen sublattice, which up to now has been neglected in experimental studies. The calculated ordering energies are, however, small as compared to the thermal energy and therefore only short-range chemical order can be expected in experiments. Thus, it is conceivable that chemically ordered local areas can act as nucleation sites for polar nano-regions, which would explain the experimentally observed relaxor behavior of NBT.

Gröting, Melanie; Hayn, Silke; Albe, Karsten

2011-08-01

97

Chemical order and local structure of the lead-free relaxor ferroelectric Na{sub 1/2}Bi{sub 1/2}TiO{sub 3}  

SciTech Connect

The A-site mixed perovskite sodium bismuth titanate (Na{sub 1/2}Bi{sub 1/2})TiO{sub 3} (NBT) is investigated by means of first-principles calculations based on density functional theory. By studying different geometries with varying occupations of the A-site, the influence of chemical order on the thermodynamic stability and local structure is explored. We find that the hybridization of Bi 6sp with O 2p-states leads to stereochemically active Bi{sup 3+} lone pairs and increases the stability of structures with high Bi concentrations in {l_brace}001{r_brace}-planes. This goes along with displacive disorder on the oxygen sublattice, which up to now has been neglected in experimental studies. The calculated ordering energies are, however, small as compared to the thermal energy and therefore only short-range chemical order can be expected in experiments. Thus, it is conceivable that chemically ordered local areas can act as nucleation sites for polar nano-regions, which would explain the experimentally observed relaxor behavior of NBT. - Graphical abstract: First-principles calculations give relative stabilities of different chemically ordered structures. The results suggest a new model for the local structure of Na{sub 1/2}Bi{sub 1/2}TiO{sub 3} with 001-ordered nano-regions embedded in a chemically disordered matrix. Chemical order/disorder additionally induces displacive disorder within the oxygen sublattice. Highlights: > Lead-free relaxor ferroelectric Na{sub 1/2}Bi{sub 1/2}TiO{sub 3} is studied by ab initio-calculations. > Structural relaxations in the oxygen sublattice are decisive for relative stabilities. > Chemical environment of oxygen determines relaxation ability. > Bi 6s{sup 2} lone pair formation is the driving force for relaxation. > New structure model: Chemically 001-ordered nano-regions embedded in disordered matrix.

Groeting, Melanie, E-mail: groeting@mm.tu-darmstadt.de [Fachgebiet Materialmodellierung, Institut fuer Materialwissenschaft, TU Darmstadt, Petersenstr. 32, 64287 Darmstadt (Germany); Hayn, Silke, E-mail: shayn@mm.tu-darmstadt.de [Fachgebiet Materialmodellierung, Institut fuer Materialwissenschaft, TU Darmstadt, Petersenstr. 32, 64287 Darmstadt (Germany); Albe, Karsten, E-mail: albe@mm.tu-darmstadt.de [Fachgebiet Materialmodellierung, Institut fuer Materialwissenschaft, TU Darmstadt, Petersenstr. 32, 64287 Darmstadt (Germany)

2011-08-15

98

Effect of field driven phase transformations on the loss tangent of relaxor ferroelectric single crystals  

NASA Astrophysics Data System (ADS)

The effect of a bias stress induced phase transformation on the large field dielectric loss in [001] cut and poled single crystal stack actuators of (1 - x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-xPT, x = 32) was experimentally characterized. Dielectric loss was observed to increase with compressive preload and electric field amplitude. The dielectric loss was determined by measuring the area within electric displacement vs. electric field hysteresis loops and the measured area was expressed in terms of an effective loss tangent. This approach matches the measured area within the hysteresis loop to an equivalent area ellipse in which the electric displacement lags the electric field by an amount, delta, under sinusoidal loading. The results collapse the measured loss as a function of bias stress and electric field amplitude reasonably close to a single curve. The measured dielectric loss behavior was attributed to the compressive stress preload driving a partial phase transformation from rhombohedral to orthorhombic and the electric field driving the reverse phase transformation from the stress induced orthorhombic phase to the zero stress rhombohedral phase. When the compressive bias stress partially or fully drives this phase transformation, the dielectric loss under unipolar electric field loading increases. This work is focused on quasi-static measurements. The large field dielectric loss is anticipated to be a function of frequency and temperature.

Gallagher, John A.; Liu, Tieqi; Lynch, Christopher S.

2013-02-01

99

Soft phonon anomalies in the relaxor ferroelectric Pb(Zn(1/3)Nb(2/3))0.92Ti0.08O3  

PubMed

Neutron inelastic scattering measurements of the polar transverse optic phonon mode dispersion in the cubic relaxor Pb(Zn(1/3)Nb(2/3))0.92Ti0.08O3 at 500 K reveal anomalous behavior in which the optic branch appears to drop precipitously into the acoustic branch at a finite value of the momentum transfer q = 0.2 A(-1) measured from the zone center. We speculate that this behavior is the result of nanometer-sized polar regions in the crystal. PMID:10990906

Gehring; Park; Shirane

2000-05-29

100

Relaxor-like dynamics of ferroelectric K(Ta1-xNbx)O3 crystals probed by inelastic light scattering  

NASA Astrophysics Data System (ADS)

The relaxor-like dynamics of the cubic-tetragonal ferroelectric phase transition was studied by Brillouin and Raman scattering in K(Ta1-xNbx)O3 (KTN) crystals with x = 0.40 (KTN40). The local symmetry breaking by the polar nanoregions (PNRs) was observed in a paraelectric phase by Raman scattering on the A1(z) mode of the PNRs with R3m symmetry. Upon cooling from a high temperature, the remarkable increase in the LA phonon damping starts at 45 K above the cubic-tetragonal phase transition temperature of TC-T = 308 K, which is defined as the intermediate temperature, T* ˜ 353 K, indicating the start of the rapid growth of the PNRs. The coupling between the LA mode and fluctuation of the PNRs caused a remarkable elastic anomaly in the vicinity of TC-T. The analysis of the temperature dependent central peak shows a critical slowing down towards TC-T, which is the evidence for the order-disorder nature of a ferroelectric phase transition. The evolution of the dynamic PNRs is discussed by the estimation of their length scale, and it is found that it starts to increase near T* and gradually grows towards TC-T.

Rahaman, M. M.; Imai, T.; Miyazu, J.; Kobayashi, J.; Tsukada, S.; Helal, M. A.; Kojima, S.

2014-08-01

101

Effect of Driving Field and Temperature on the Response Behavior of Ferroelectric Actuator and Sensor Materials  

Microsoft Academic Search

Three commonly used ferroelectric actuator and sensor materials, namely polyvinylidene fluoride copolymers, lead zirconate titanate piezoceramics (PZT), and lead magnesium niobate-lead titanate relaxors (PMN-PT) at low PT content, are characterized with respect to temperature and driving field amplitude. It is shown that changes in the response and loss with the driving field amplitude are mainly caused by irreversible process and

Q. M Zhang; H. Wang; J. Zhao

1995-01-01

102

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

SciTech Connect

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

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

2013-03-18

103

Mechanical stress modified ferroelectric aging behavior  

NASA Astrophysics Data System (ADS)

Mechanical stress effect on aging behavior of Bi3.25La0.75Ti3O12 (BLT) and PbZr0.53Ti0.47O3 (PZT) films was investigated. It is found that the remnant polarization decreases with time while the coercive field increases in stress-free BLT films. For unconfined PZT films, both the remnant polarization and the coercive field decrease as time elapses. The applied tensile stress weakens the aging of remnant polarization of BLT films but strengthens the aging of coercive field, while the applied tensile stress possesses opposite effect. In contrary, the applied compressive stress simultaneously improves the aging behavior of both remnant polarization and coercive field of PZT films. Mechanical-stress-induced variation of domain wall mobility in different materials was suggested as the possible origin of these observations. This work indicates that the aging behavior modification using stress could be realized, and it is helpful for promoting the reliability of ferroelectric films for industrial applications.

Xu, Tingting; Kan, Yi; Jin, Yaming; Sun, Hui; Du, Yingchao; Wu, Xiumei; Bo, Huifeng; Cai, Wei; Huang, Fengzhen; Lu, Xiaomei; Zhu, Jinsong

2013-05-01

104

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

105

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

106

Controlling Dielectric and Relaxor-Ferroelectric Properties for Energy Storage by Tuning Pb0.92La0.08Zr0.52Ti0.48O3 Film Thickness.  

PubMed

The energy storage properties of Pb0.92La0.08Zr0.52Ti0.48O3 (PLZT) films grown via pulsed laser deposition were evaluated at variable film thickness of 125, 250, 500, and 1000 nm. These films show high dielectric permittivity up to ?1200. Cyclic I-V measurements were used to evaluate the dielectric properties of these thin films, which not only provide the total electric displacement, but also separate contributions from each of the relevant components including electric conductivity (D1), dielectric capacitance (D2), and relaxor-ferroelectric domain switching polarization (P). The results show that, as the film thickness increases, the material transits from a linear dielectric to nonlinear relaxor-ferroelectric. While the energy storage per volume increases with the film thickness, the energy storage efficiency drops from ?80% to ?30%. The PLZT films can be optimized for different energy storage applications by tuning the film thickness to optimize between the linear and nonlinear dielectric properties and energy storage efficiency. PMID:25405727

Brown, Emery; Ma, Chunrui; Acharya, Jagaran; Ma, Beihai; Wu, Judy; Li, Jun

2014-12-24

107

Quasistatic Field-Cooled Dielectric Response in Relaxor Materials  

Microsoft Academic Search

Quasistatic dielectric response in PMN relaxor system was studied as a function of the dc electric field by utilizing a charge accumulation technique in a field-cooled experiment. An anomaly associated with the onset of spontaneous polarization was observed in the linear field-cooled dielectric response when crossing electric field threshold line E T (T) separating the relaxor and ferroelectric phases in

Z. Kutnjak; A. Levstik; R. Pirc

2002-01-01

108

Auxetic behavior under electrical loads in an induced ferroelectric phase  

NASA Astrophysics Data System (ADS)

The longitudinal and transverse strains were measured as a function of applied electric fields in a bulk ceramic sample of Pb0.99Nb0.02[(Zr0.57Sn0.43)0.94Ti0.06]0.98O3 at room temperature. Instead of a transverse contraction, a transverse expansion was observed in the electric-field-induced ferroelectric phase after the antiferroelectric-to-ferroelectric phase transition. Therefore, an auxetic behavior was established in monolithic ferroelectric polycrystalline ceramics under electrical loads. The behavior is characterized by a negative strain ratio that is analogous to the Poisson's ratio. The transverse expansion leads to a large hydrostatic piezoelectric coefficient dh, which suggests new applications of antiferroelectric ceramics in piezoelectric devices.

Tan, X.; Jo, W.; Granzow, T.; Frederick, J.; Aulbach, E.; Rödel, J.

2009-01-01

109

From Ferroelectric to Quantum Paraelectric: KTa1-xNbxO3 (KTN), A Model System  

NASA Astrophysics Data System (ADS)

The mixed perovskite oxides KTa1-xNbxO3, or KTN, are a model system for studying ferroelectric behavior and phase transitions under pressure. Crystals with x > 0.1 exhibit ferroelectric soft-mode behavior and a sequence of phase transitions, while for x ? 0.02 a pressure-induced ferroelectric-to-relaxor crossover occurs. The system also exhibits a pressure-induced crossover from classical-to-quantum behavior ultimately leading to the complete suppression of the phase transition and the formation of a quantum paraelectric state.

Samara, G. A.

2004-07-01

110

From ferroelectric to quantum paraelectric : KTa1-xNbxO3 (KTN), a model system.  

SciTech Connect

The mixed perovskite oxides KTa{sub 1-x}Nb{sub x}O{sub 3}, or KTN, are a model system for studying ferroelectric behavior and phase transitions under pressure. Crystals with x > 0.1 exhibit ferroelectric soft-mode behavior and a sequence of phase transitions, while for x {le} 0.02 a pressure-induced ferroelectric-to-relaxor crossover occurs. The system also exhibits a pressure-induced crossover from classical-to-quantum behavior ultimately leading to the complete suppression of the phase transition and the formation of a quantum paraelectric state.

Samara, George A.

2003-08-01

111

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. PMID:20368462

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

2010-01-01

112

Magnetoelectric relaxor  

Microsoft Academic Search

The site and charge disordered solid solution 0.8Pb(Fe1\\/2Nb1\\/2)O3-0.2Pb(Mg1\\/2W1\\/2)O3 is a magnetoelectric relaxor which shows broad and frequency dependent maxima both in the electric as well as in the magnetic susceptibilities. The Vogel-Fulcher-type electric relaxor freeze-out is accompanied by a significant magnetic anomaly demonstrating magnetoelectric coupling. Thus, a magnetoelectric effect is observed in a system exhibiting only mesoscopic and no long

A. Levstik; V. Bobnar; C. Filipic; J. Holc; M. Kosec; R. Blinc; Z. Trontelj; Z. Jaglicic

2007-01-01

113

First Principles Phase Diagram Calculations for the System NaNbO3-KNbO3: can spinodal decomposition generate relaxor  

E-print Network

Pb(Zr1-X,TiX)O3, which is the most widely used transducer, actuator and ferroelectric- sensor generate relaxor ferroelectricity? B.P. Burton Materials Science and Engineering Laboratory, Ceramics calculation; lead-free; relaxor ferroelectric; spinodal decomposition. Submitted to Applied Physics Letters 04

Burton, Benjamin P.

114

Aging in the relaxor and ferroelectric state of Fe-doped (1-x)(Bi{sub 1/2}Na{sub 1/2})TiO{sub 3}-xBaTiO{sub 3} piezoelectric ceramics  

SciTech Connect

Aging of piezoelectric properties was investigated in lead-free (1???x)(Bi{sub 1/2}Na{sub 1/2})TiO{sub 3}-xBaTiO{sub 3} doped with 1at.?% Fe. The relaxor character of the un-poled material prevents macroscopic aging effects, while in the field-induced ferroelectric phase aging phenomena are similar to those found in lead zirconate titanate or barium titanate. Most prominent aging effects are the development of an internal bias field and the decrease of switchable polarization. These effects are temperature activated, and can be explained in the framework of defect complex reorientation. This picture is further supported by electron paramagnetic resonance spectra indicating the existence of (Fe{sub Ti}{sup ?}?V{sub O}{sup ••}){sup •} defect complexes in the Fe-doped material.

Sapper, Eva; Dittmer, Robert; Rödel, Jürgen [Materials Science Department, Technische Universität Darmstadt, 64287 Darmstadt (Germany); Damjanovic, Dragan [Ceramics Laboratory, École Polytechnique Fédérale de Lausanne, Lausanne 1015 (Switzerland); Erdem, Emre [Institute of Physical Chemistry I, Universität Freiburg, 79104 Freiburg (Germany); Keeble, David J. [Division of Electronic Engineering and Physics, University of Dundee, Dundee DD1 4HN (United Kingdom); Jo, Wook [School of Materials Science and Engineering, Ulsan National Institute of Science and Technology, Ulsan 689-798 (Korea, Republic of); Granzow, Torsten [Centre de Recherche Public—Gabriel Lippmann, L-4422 Belvaux (Luxembourg)

2014-09-14

115

Coupling between octahedral tilting and ferroelectric order in tetragonal tungsten bronze-structured dielectrics  

NASA Astrophysics Data System (ADS)

Strong coupling between local polar displacements and a commensurate octahedral tilting is proposed to explain the onset of classic ferroelectric behavior in tetragonal tungsten bronzelike dielectrics Ba2LaxNd1-xNb3Ti2O15. The ferroelectric phase transition is associated with a discontinuous non-lock-in transformation of an incommensurate tilted structure to a commensurate superstructure. In a manner reminiscent of perovskitelike oxides, the driving force for commensurate tilting increases as the average ionic radius of the rare-earth ion decreases; no classical ferroelectric transition is observed for compositions with x >0.75, which remain incommensurate and exhibit only relaxor behavior below room temperature.

Levin, Igor; Stennett, Martin C.; Miles, Gabrielle C.; Woodward, David. I.; West, Anthony R.; Reaney, Ian M.

2006-09-01

116

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

PubMed

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

117

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

118

Soft Phonon Anomalies in the Relaxor Ferroelectric Pb(Zn{sub 1/3}Nb{sub 2/3}) {sub 0.92}Ti{sub 0.08}O{sub 3}  

SciTech Connect

Neutron inelastic scattering measurements of the polar transverse optic phonon mode dispersion in the cubic relaxor Pb(Zn{sub 1/3}Nb{sub 2/3}){sub 0.92}Ti{sub 0.08}O{sub 3} at 500 K reveal anomalous behavior 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{sup -1} measured from the zone center. We speculate that this behavior is the result of nanometer-sized polar regions in the crystal. (c) 2000 The American Physical Society.

Gehring, P. M. [NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States)] [NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); Park, S.-E. [Materials Research Laboratory, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States)] [Materials Research Laboratory, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Shirane, G. [Physics Department, Brookhaven National Laboratory, Upton, New York 11973 (United States)] [Physics Department, Brookhaven National Laboratory, Upton, New York 11973 (United States)

2000-05-29

119

The effect of ac field amplitude on the relaxor behaviors in Langmuir-Blodgett terpolymer films  

NASA Astrophysics Data System (ADS)

The ac field (Eac) amplitude dependence of dielectric response has been investigated for poly (vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) relaxor terpolymer films. The frequency dependence of the temperature of the permittivity maximum Tm can be well described by the Vogel-Fulcher relation for Eac in the range from 1.33 to 80 MV/m. Tm remains nearly constant at an Eac level lower than 13.3 MV/m, and starts decreasing with Eac increases further. The two parameters fitting to the Vogel-Fulcher relation, freezing temperature Tf and activation energy Ea, vary little for Eac below 26.7 MV/m and then Tf decreases, while Ea increases for higher Eac level.

Meng, X. J.; Wang, J. L.; Xu, H. S.; Sun, J. L.; Chu, J. H.

2009-12-01

120

Dipolar-glass-like relaxor ferroelectric behaviour in the 0.5BaTiO3-0.5Bi(Mg1/2Ti1/2)O3 electroceramic  

NASA Astrophysics Data System (ADS)

In this study, the dielectric and ferroelectric switching behaviour of 0.5BaTiO3-0.5Bi(Mg1/2Ti1/2)O3 (BT-BMT) ceramics are investigated. The BT-BMT ceramic exhibits a typical dipolar-glass-like, dielectric polarisation relaxation. This is attributed to the 15 distinct possible local A4B2 configurations around the O ions and the effect this unavoidable local compositional variability has on the dipole relaxation behaviour of inherent 1-D ?111? dipole chains, arising from correlated off-centre displacements of Bi3+ and Ti4+ ions along local ?111? directions. On the other hand, switchable polarisation under strong applied electric fields is observed on different length scales accompanied by the appearance of strong polarisation relaxation, as observed via time-delayed piezoresponse hysteresis loop measurements. These experimental results demonstrate that this BT-BMT ceramic is relaxor ferroelectric in nature, although it exhibits dipolar-glass-like dielectric relaxation behaviour.

Wang, Jian; Liu, Yun; Li, Qian; Lau, Kenny; Withers, Ray L.; Li, Zhenrong; Xu, Zhuo

2013-07-01

121

Nanoscale behavior of ferroelectric domains in perovskite thin films  

NASA Astrophysics Data System (ADS)

Controlling the polarization of ferroelectrics plays an increasingly important role in many technological devices including ferroelectric memory, tunable communication filters, and vibrational energy scavengers. To advance the development of ferroelectric devices, we must improve our understanding of the complex internal domain structure of ferroelectric materials. Because these domains are only 50-500 nm wide, they have historically been difficult to probe. This dissertation demonstrates how nanoscale ferroelectric domain configurations can be tailored in epitaxial perovskite thin films by controlling the electromechanical boundary conditions of the film. Epitaxial films of BiFeO3 and Pb(Zr,Ti)O3 were used as model systems because the latter is a mainstay in piezoelectric sensing and actuating applications and the former is a promising Pb-free magnetoelectric-ferroelectric with large polarization, strong piezoelectricity, and multiple ferroelastic domain wall variants. The as-grown domain structures of epitaxial BiFeO3 films deposited on (001)-oriented SrTiO3 substrates were investigated using piezoelectric force microscopy. The equilibrium ground state consists of alternating domain stripes consisting of only two ferroelastic variants, separated by 71° domain walls. Selective activation of 71° and 109° ferroelastic switching---which is important for magnetoelectric applications---was achieved by controlling the strength of the applied electric field. A similar behavior was found in BiFeO3 films deposited on (110)-oriented SrTiO 3. The novel characterization technique of planar electrode piezoelectric force microscopy is introduced as a non-destructive method for viewing nanoscale domains at intermediate stages of the poling process. This apparatus was used to selectively enable 109° or 71° reversible rotation of the 71° domain stripes in BiFeO3 films. Domain stripe rotation was then used to achieve magnetoelectric switching of a permanent magnet, and also to modulate the photo-electric effect in BiFeO3 domain walls. A novel concept for harnessing electricity from ferroelastic domain wall motion is applied to vibrational energy scavenging. Methods for imaging domains while deforming the Pb(Zr,Ti)O3 or BiFeO3 film with a micromachined cantilever and magnetic actuation or by three-point bending are presented. Reverse polarized domains in BiFeO3 were found to grow under compressive strain by 180° domain wall motion that maintains the equilibrium 71° domain stripes.

Shafer, Padraic Corey

122

Relaxor ferroelectrics for electrostrictive transducer  

NASA Astrophysics Data System (ADS)

The objective of this program is to investigate the potential of electrostrictive actuator materials for use in NAVY-type sonar. The anticipated performance requirements for such materials is summarized in the following: Operating temperature range 0-30 C; High sensitivity; Large E-field induced strain; Minimal hysteresis and low loss; Frequency of operation; and Mechanically stiff (low compliance). Additional requirements include operational E-field strain under prestress, and duty cycles.

Shrout, Thomas R.; Jang, Sei-Joo

1992-01-01

123

Dielectric Spectroscopy and conductivity relaxation of PSN-PST relaxor thin films  

NASA Astrophysics Data System (ADS)

-abstract- Relaxor ferroelectric materials exhibit singular dielectric relaxation. They have large dielectric constant, high piezo and electrostrictive coefficients that make them useful for sensors, actuators and ferroelectric related devices. We have prepared PSN-PST relaxor thin films by pulsed laser deposition technique. Studies of dielectric properties, as a function of temperature (100-650K) and frequency (40 Hz --1 MHz) have shown that the materials have diffuse phase transition along with the frequency dispersion. The magnitude of dielectric constant and the temperature of maximum permitivitty (Tm) differ from those in the bulk form. However, its conductivity behavior follows similar trend in both bulk and thin film forms. The ac conductivity exhibits frequency independent plateau at lower frequencies followed by a dispersion region at higher frequencies. The observed dispersion of conductivity with frequency can be described by a power law ?( ?)=?dc+A?^n with n>1. The unusual high n value is due to glassy like nature of the relaxor system and it is explained in terms of polaron assisted ionic mechanism. Detailed results will be presented.

Correa, Margarita; Baskaran, Natasan; Katiyar, Ram

2007-03-01

124

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

SciTech Connect

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

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

2006-10-01

125

Nonlinear dielectric response of relaxor PLZT ceramics in a dc bias electric field  

Microsoft Academic Search

The temperature dependences of the first, ?1, and the third, ?3, harmonic dielectric responses have been simultaneously measured in 9\\/65\\/35 PLZT ceramics in a dc bias electric field, higher than the critical field. Additional peaks in both, ?1 and ?3, superimposed on the broad dispersive relaxor background were observed, indicating induced ergodic relaxor to ferroelectric phase transition. It is shown

Vid Bobnar; Zdravko Kutnjak; Adrijan Levstik

2001-01-01

126

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.

127

Longitudinal elastic behavior of the mixed ferroelectric KTN  

Microsoft Academic Search

Because of the essential role played by anharmonic elastic forces and strain in ferroelectric transitions, elastic measurements can provide direct evidence of the various stages which ferroelectrics go through when approaching the transition. In the case of mixed ferroelectrics like KTN, the transition occurs in two distinct stages, clearly revealed by ultrasonic measurements of the longitudinal C11 elastic constant. In

X. M. Wang; J. Toulouse; L. A. Boatner

1990-01-01

128

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

NASA Astrophysics Data System (ADS)

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

Stringer, Craig J.

129

Finite element analysis of a multilayer piezoelectric actuator taking into account the ferroelectric and ferroelastic behaviors  

Microsoft Academic Search

Ferroelasticity and ferroelectricity are the non-linear behaviors exhibited by piezoceramics, especially in the case of high electric field or stress. Many studies have focused on the role of ferroelastic and ferroelectric switching in fracture of actuators. However, engineering reliability analyzes are carried out with tools like finite element software that do not take into account these non-linear phenomena. To overcome

Mourad Elhadrouz; Tarak Ben Zineb; Etienne Patoor

2006-01-01

130

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

SciTech Connect

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

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

2014-04-14

131

Elastic and anelastic relaxations in the relaxor ferroelectric Pb(Mg1/3Nb2/3)O3: II. Strain-order parameter coupling and dynamic softening mechanisms.  

PubMed

Elastic and anelastic behaviour of single crystal and ceramic samples of Pb(Mg(1/3)Nb(2/3))O(3) has been investigated at frequencies of ~0.1-1.2 MHz through the temperature interval 10-800 K by resonant ultrasound spectroscopy (RUS). Comparison with data from the literature shows that softening of the shear modulus between the Burns temperature and the freezing interval is independent of frequency. The softening is attributed to coupling between acoustic modes and the relaxation mode(s) responsible for central peaks in Raman and neutron scattering spectra below the Burns temperature, and can be described with Vogel-Fulcher parameters. Shear elastic compliance and dielectric permittivity show similar patterns of temperature dependence through the freezing interval, demonstrating strong coupling between ferroelectric polarization and strain such that the response to applied stress is more or less the same as the response to an applied electric field, with a frequency dependence consistent with Vogel-Fulcher-like freezing in both cases. Differences in detail show, however, that shearing induces flipping between different twin orientations, in comparison with the influence of an electric field, which induces 180° flipping: the activation energy barrier for the former appears to be higher than for the latter. Below the freezing interval, the anelastic loss also has a similar pattern of evolution to the dielectric loss, signifying again that essentially the same mechanism is involved in the freezing process. Overall softening at low temperatures is attributed to the contributions of strain relaxations due to coupling with the local ferroelectric order parameter and of coupling between acoustic modes and continuing relaxational modes of the polar nanostructure. Dissipation is attributed to movement of boundaries between PNRs or between correlated clusters of PNRs. Overall, strain coupling is fundamental to the development of the characteristic strain, dielectric and elastic properties of relaxors. PMID:22186067

Carpenter, M A; Bryson, J F J; Catalan, G; Zhang, S J; Donnelly, N J

2012-02-01

132

Pressure-induced phase transitions and structure of chemically ordered nanoregions in the lead-free relaxor ferroelectric Na1/2Bi1/2TiO3  

NASA Astrophysics Data System (ADS)

We investigate the phase stability of Na1/2Bi1/2TiO3, a prototype lead-free relaxor material, under pressure. By means of total energy calculations within density functional theory, we study the pressure stability of several structures with polar and antipolar distortions, in-phase and out-of-phase tilts, and different chemically ordered configurations. Under positive (compressive) pressure an orthorhombic Pbnm-like phase is stabilized above 3 GPa. At negative (tensile) pressure a non-tilted polar P4mm-like phase is stable. At zero pressure two phases are coexisting. The local chemical configuration determines whether the high-pressure Pbnm-like or another tilted and polar R3c-like structure is favored. Thus, two different variants of pressure phase diagrams depending on the cation arrangement are obtained, which raises the question of the existence of a mixed phase ground state in the disordered system. We discuss the stability of the mixed phase state in terms of lattice and tilt misfits and possible shapes and ferroic properties of the coexisting regions with different average structures. Our results clearly support the view that there are chemically ordered nanoregions with their own local ferroic properties embedded in a chemically disordered ferroelectric matrix representing the ground state.

Gröting, Melanie; Kornev, Igor; Dkhil, Brahim; Albe, Karsten

2012-10-01

133

From Ferroelectric to Quantum Paraelectric: KTa 1-x Nb x O 3 (KTN), a Model System  

Microsoft Academic Search

\\u000a The effects of pressure on the dielectric properties and phase transitions were investigated for a number of KTN compositions\\u000a revealing the richness of phenomena involved. Crystals with x > 0.1 exhibit ferroelectric soft-mode behavior and for x ? 0.02 a pressure-induced ferroelectric-to-relaxor crossover occurs. The system also exhibits a pressure-induced crossover\\u000a from classical-to-quantum behavior ultimately leading to the complete suppression

G. A. Samara; George A

2003-01-01

134

Condensation and Slow Dynamics of Polar Nanoregions in Lead Relaxors  

NASA Astrophysics Data System (ADS)

It is now well established that the unique properties of relaxor ferroelectrics are due to the presence of polar nanoregions (PNR's). We present recent results from Neutron and Raman scattering of single crystals of PZN, PZN-xPT, and PMN. Both sets of measurements provide information on the condensation of the PNR's and on their slow dynamics, directly through the Central Peak and, indirectly, through their coupling to transverse phonons. A comparative analysis of these results allows identification of three stages in the evolution of the PNR's with decreasing temperature: a purely dynamic stage, a quasi-static stage with reorientational motion and a frozen stage. A model is proposed, based on a prior study of KTN, which explains the special behavior of the transverse phonons (TO and TA) in terms of their mutual coupling through the rotations of the PNR's.

La-Orauttapong, D.; Svitelskiy, O.; Toulouse, J.

2003-08-01

135

Ferroelectric Behavior of CuO Doped Ba (Ti0.91Zr0.09) O3 Ceramics  

Microsoft Academic Search

Ba (Ti0.91Zr0.09) O3 ceramics doped with CuO were prepared by a solid phase reaction. The ferroelectric properties of Ba (Ti0.91Zr0.09) O3 ceramics were investigated. The results revealed that the materials are of relaxor type at Orthorhombic-Tetragonal phase transition point and undergoes a diffuse phase transition at Tetragonal-Cubic phase transition point. A non-linear P-E loop and narrow loop are observed, which

Ding Shihua; Song Tianxiu; Chen Tao

2010-01-01

136

Relaxor behavior of K0.5La0.5Bi2Nb2O9 ceramics  

NASA Astrophysics Data System (ADS)

K0.5La0.5Bi2Nb2O9, a relaxor, was synthesized and the structural studies confirmed it to be an n =2 member of the Aurivillius oxides. The 1/2{h00} and 1/2{hk0} types of superlattice reflections in the electron diffraction patterns reflected the presence of ordered polar regions. A broad dielectric peak with frequency dependent dielectric maximum temperature was observed. The dielectric relaxation obeyed the Vogel-Fulcher relation wherein Ea=0.04eV, Tf=428K,and ?o=1010Hz. The diffuseness parameter ? =2.003 established the relaxor nature and it was attributed to the A-site cationic disorder. The piezoelectric d31 coefficient was 0.5pC/N at 300K and 2pC/N at 480K.

Karthik, C.; Ravishankar, N.; Varma, K. B. R.; Maglione, Mario; Vondermuhll, R.; Etourneau, J.

2006-07-01

137

Curie constant in relaxor ferroelectrics Pb(Zn1/3Nb2/3)O3-8%PbTiO3  

NASA Astrophysics Data System (ADS)

The dielectric permittivity along the [001]c direction of the pseudocubic coordinate in Pb(Zn1/3Nb2/3)O3-8%PbTiO3 (PZN-8%PT) was investigated in a wide temperature range of 30-640 °C. The determination of the Curie constant in PZN-8%PT was attempted, using the dielectric permittivity above the Burns temperature, to evaluate the bulk property in the ferroelectric phase as an average structure with reduced heterogeneity. It was confirmed that the reported temperature dependence of the spontaneous polarization can be quantitatively well reproduced on the basis of the Landau-type free energy.

Iwata, Makoto; Ido, Tomoya; Maeda, Masaki; Ishibashi, Yoshihiro

2014-09-01

138

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

E-print Network

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

Osnabrück, Universität

139

High-resolution structure studies and magnetoelectric coupling of relaxor multiferroic Pb (F e0.5N b0.5) O3  

NASA Astrophysics Data System (ADS)

Pb (F e0.5N b0.5) O3 (PFN), one of the few relaxor multiferroic systems, has a G -type antiferromagnetic transition at TN=143 K and a ferroelectric transition at TC=385 K . By using high-resolution neutron-diffraction experiments and a total scattering technique, we paint a comprehensive picture of the long- and short-range structures of PFN: (i) a clear sign of short-range structural correlation above TC, (ii) no sign of the negative thermal expansion behavior reported in a previous study, and (iii) clearest evidence thus far of magnetoelectric coupling below TN. We conclude that at the heart of the unusual relaxor multiferroic behavior lies the disorder between Fe3 + and Nb5 + atoms. We argue that this disorder gives rise to short-range structural correlations arising from O disorder in addition to Pb displacement.

Sim, Hasung; Peets, Darren C.; Lee, Sanghyun; Lee, Seongsu; Kamiyama, T.; Ikeda, K.; Otomo, T.; Cheong, S.-W.; Park, Je-Geun

2014-12-01

140

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

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

141

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

142

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

143

Linear and nonlinear dielectric constant as function of bias electric field in relaxor materials  

Microsoft Academic Search

The quasistatic linear and nonlinear dielectric constants ?S in 9\\/65\\/35 PLZT ceramics and PMN crystal were investigated by means of the charge accumulation technique and by monitoring the first, ?1, and the third, ?3, harmonic response. The zero field cooled and field cooled static susceptibilities show a crossover from a nonergodic relaxor to inhomogeneous ferroelectric behaviour. At electric fields above

Zdravko Kutnjak; Cene Filipi?; Adrijan Levstik

2001-01-01

144

Role of point defects in bipolar fatigue behavior of Bi(Mg{sub 1/2}Ti{sub 1/2})O{sub 3} modified (Bi{sub 1/2}K{sub 1/2})TiO{sub 3}-(Bi{sub 1/2}Na{sub 1/2})TiO{sub 3} relaxor ceramics  

SciTech Connect

Lead-free Bi(Mg{sub 1/2}Ti{sub 1/2})O{sub 3}-(Bi{sub 1/2}K{sub 1/2})TiO{sub 3}-(Bi{sub 1/2}Na{sub 1/2})TiO{sub 3} (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 10{sup 6} 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, E-mail: nitishkumar.iitk@gmail.com; Ansell, Troy Y.; Cann, David P. [Materials Science, School of Mechanical, Industrial, and Manufacturing Engineering, Oregon State University, Corvallis, Oregon 97331 (United States)

2014-04-21

145

High-temperature dielectric response of (1-x)Pb(Mg1\\/3Nb2\\/3)O3-xPbTiO3: Does Burns temperature exist in ferroelectric relaxors?  

Microsoft Academic Search

It has been considered that polar nanoregions (PNRs) in relaxors form at Burns temperature Td~600 K. High-temperature dielectric investigations of Pb(Mg1\\/3Nb2\\/3)O3 (PMN) and 0.7PMN-0.3PbTiO3 reveal, however, that the dielectric dispersion around 600 K appears due to the surface-layer contributions. The intrinsic response, analyzed in terms of the universal scaling, imply much higher Td or formation of PNRs in a broad

Vid Bobnar; Cene Filipic; Adrijan Levstik; Zdravko Kutnjak

2010-01-01

146

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

NASA Astrophysics Data System (ADS)

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

Vanga, Raghav

147

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

NASA Astrophysics Data System (ADS)

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

Vanga, Raghav

148

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

NASA Astrophysics Data System (ADS)

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

He, Xiangtong

149

Interpretation of the odd-even behavior for the emergence of ferroelectricity and antiferroelectricity in bent-core mesogens  

NASA Astrophysics Data System (ADS)

Simple theoretical interpretation has been made on the previously reported odd-even behavior of the emergence of ferroelectricity and antiferroelectricity in homologous series of bent-core mesogens with the same chiral end chains (S,S) ; compounds with even and odd carbon numbers (including oxygen) exhibit ferroelectric and antiferroelectric B2 phases, respectively. The odd-even behavior was confirmed in newly synthesized racemic compounds with chiral end chains of R and S forms (R,S) together with (R,R) and (S,S) forms. According to our theoretical interpretation, ferroelectricity should be more stable in (R,S) compounds than in (S,S) compounds. Actually, the transition temperature from the isotropic phase to the Sm-CP phase was higher and the temperature range of the B2 phase was broader in the (R,S) compound than in the (S,S) compound.

Nishida, Koushi; ?epi?, Mojca; Kim, Won Jeon; Lee, Seng Kue; Heo, Sung; Lee, Jong Gun; Takanishi, Yoichi; Ishikawa, Ken; Kang, Kyung-Tae; Watanabe, Junji; Takezoe, Hideo

2006-08-01

150

J. Am. Ceram. Soc., 80 [6] 146268 (1997) Domain-Related Phase Transitionlike Behavior in Lead Zinc Niobate  

E-print Network

J. Am. Ceram. Soc., 80 [6] 1462­68 (1997) Domain-Related Phase Transitionlike Behavior in Lead Zinc observed by severalThe relaxor ferroelectric lead zinc niobate (Pb(Zn1/3Nb2/3)O3) methods, such as optical LEAD zinc niobate, Pb(Zn1/3Nb2/3)O3 (PZN), single crystals Single crystals of PZN were grown using

Cao, Wenwu

151

Ferroelectric Materials for Electromechanical Transducer Applications  

NASA Astrophysics Data System (ADS)

Many advantages of ferroelectric compositions in the lead zirconate:lead titanate (PZT) solid solutions for both sensing and actuation are explored. The state of understanding of both intrinsic single domain and extrinsic domain wall and phase boundary contribution to response is described, and the composition manipulations used to modifiy the extrinsic responses explored. In lead magnesium niobate (PMN) based solid solution a nanometer scale ordering of Mg:Nb cations breaks up the conventional ferroelectric coupling leading to glass like relaxor ferroelectric response. The fact that problems arising from density and rigidity of PZT for large area transducers are markedly worked out in piezoceramic:polymer composites is also briefly explored.

Cross, Leslie

1995-05-01

152

Electric field induced metastable ferroelectric phase and its behavior in (Pb, La)(Zr, Sn, Ti)O3 antiferroelectric single crystal near morphotropic  

E-print Network

Electric field induced metastable ferroelectric phase and its behavior in (Pb, La)(Zr, Sn, Ti)O3-ray diffraction analysis and electrical properties reveal coexistence of antiferroelectric/ferroelectric (FE the PLZST single crystal a promising candidate for thermal switch and actuator application. VC 2014 AIP

Cao, Wenwu

153

Relaxor-PT single crystals: observations and developments.  

PubMed

Relaxor-PT based ferroelectric single crystals Pb(Zn?/?)Nb(?/?)O?-PbTiO? (PZNT) and Pb(Mg?/?)Nb(?/?)O?-PbTiO? (PMNT) offer high performance with ultra-high electromechanical coupling factors k?? > 0.9 and piezoelectric coefficients d??s > 1500 pC/N. However, the usage temperature range of these perovskite single crystals is limited by T(RT)-the rhombohedral to tetragonal phase transition temperature, which occurs at significantly lower temperatures than the Curie temperature T(C), a consequence of curved morphotropic phase boundaries (MPBs). Furthermore, these <001>-oriented crystals exhibit low mechanical quality Q and coercive fields, restricting their usage in high-power applications. In this survey, recent developments on binary and ternary perovskite relaxor-PT crystal systems are reviewed with respect to their temperature usage range. General trends of dielectric and piezoelectric properties of relaxor-PT crystal systems are discussed in relation to their respective T(C)/T(RT). In addition, two approaches have been implemented to improve mechanical Q, including acceptor dopants, analogous to hard polycrystalline ceramics, and anisotropic domain engineering, enabling low-loss crystals with high coupling for high-power applications. PMID:20889397

Zhang, Shujun; Shrout, Thomas

2010-10-01

154

KTa0.6Nb0.4O3 ferroelectric thin film behavior at microwave frequencies for tunable applications.  

PubMed

In this study about the relationships between structural and microwave electrical properties of KTa(1-x)NbxO3 (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 the substrate on the circuit behavior and, notably, on the tuning factor. PMID:17186908

Laur, Vincent; Rousseau, Anthony; Tanné, Gérard; Laurent, Paul; Députier, Stéphanie; Guilloux-Viry, Maryline; Huret, Fabrice

2006-12-01

155

Density of vibration states and ferroelectric properties of complex perovskites  

NASA Astrophysics Data System (ADS)

We studied the effect of temperature on density of vibrational states of model complex perovskites PbMg1/3Nb2/3O3 (PMN), PbMg1/3Ta2/3O3 (PMT), and BaMg1/3Ta2/3O3 (BMT) by inelastic neutron scattering. It has been found that PMN and PMT relaxor ferroelectrics exhibit an anomalous temperature evolution of the density of vibrational states G(E), while G(E) in the BMT compound does not demonstrate any temperature evolution. It is shown that there is a correlation between the temperature behaviors of the dielectric response and vibrational spectra of all the complex perovskites studied. Possible reasons for variation in G(E) in these materials are discussed.

Gvasaliya, S. N.; Lushnikov, S. G.; Sashin, I. L.; Shaplygina, T. A.

2003-07-01

156

Abstract: Six different behavioral models for ferroelectric capacitors are surveyed with an emphasis on their usefulness in the transient circuit simulation of integrated nonvolatile memories. These models can be  

E-print Network

Abstract: Six different behavioral models for ferroelectric capacitors are surveyed and those that rely on the switching current of a ferroelectric capacitor. The former often involves a continuous cycling of a ferroelectric capacitor with a sinusoidal waveform. The latter employs a pulse

Sheikholeslami, Ali

157

Ferroelectric Transition and Curie—Weiss Behavior in Some Filled Tungsten Bronze Ceramics  

NASA Astrophysics Data System (ADS)

Ferroelectric transitions in filled tungsten bronze ceramics Sr4R2Ti4Nb6O30, Sr5RTi3Nb7O30 (R=La, Nb, Sm & Eu) and Ba4Nd2Ti4Nb6O30 are investigated with differential scanning calorimetry (DSC) and the Curie—Weiss law fitting to the dielectric constant. The magnitude of the Curie-Weiss constant C ~ 105 suggests displacement-type ferroelectric transition in the present compounds. The large ?T difference between dielectric maximum temperature Tm and Curie—Weiss temperature T0) values indicate the difficult formation of ferroelectric domains or polar nanoregions in the present compounds and also the characteristics of the first order ferroelectric transition. Three categories are suggested for the ferroelectric transition in the above tungsten bronzes. The ferroelectric transition exhibits large thermal hysteresis. According to the DSC results, gradual recovery of the endothermic peak occurs after aging at temperature below the Curie point, indicating the gradual stability of the ferroelectric phase after cooling from the high-temperature para-electric phase. The relationship between the Curie—Weiss law fitting parameters and the nature of the ferroelectric transition is modified for the filled tungsten bronzes.

Zhu, Xiao-Li; Chen, Xiang-Ming

2014-01-01

158

Finite element analysis of a multilayer piezoelectric actuator taking into account the ferroelectric and ferroelastic behaviors  

Microsoft Academic Search

Ferroelasticity and ferroelectricity are the non linear behaviours exhibited by piezoceramics, especially in the case of high electric field or stress. Many studies have focused on the role of ferroelastic and ferroelectric switching in fracture of actuators. However, engineering reliability analyses are carried out with tools like finite element software that do not take into account these non linear phenomena.

M. Elhadrouz; T. Ben Zineb; E. Patoor

2005-01-01

159

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

160

Ferroelectric non-hysteresis actuator for microwave tuneable devices  

Microsoft Academic Search

Low loss and highly tuneable microwave filters controlled by piezoelectric actuator are discussed. Dielectric or metallic parts of device should have the piezo-dirigible air gap between them. The most important for these devices is to use non-hysteresis relaxor ferroelectric ceramics with large electrostriction. Electromechanic way of control has restriction in the speed of operation, and this problem is estimated by

Y. M. Poplavko; S. A. Voronov

2010-01-01

161

Effects of Chemical Treatments on the Electrical Behaviors of Ferroelectric Poly(vinylidene fluoride-trifluoroethylene) Copolymer for Nonvolatile Memory Device Applications  

Microsoft Academic Search

Ensuring the sound ferroelectric behaviors of the ferroelectric copolymer poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] after various fabrication processes routinely performed for the device integration is very important for the practical nonvolatile memory applications using P(VDF-TrFE). In this work, the changes in the electrical and physical properties of the P(VDF-TrFE) thin film were investigated, assuming that some chemical treatments are involved in the

Sung-Min Yoon; Soon-Won Jung; Shin-Hyuk Yang; Seung-Youl Kang; Chi-Sun Hwang; Byoung-Gon Yu

2009-01-01

162

Ferroelectric phase transition and soft-mode behavior in BaxSr1-xTiO3: a refined treatment of a quasi-harmonic model  

NASA Astrophysics Data System (ADS)

The composition and temperature dependences of the soft-mode and ferroelectric phase transition in BaxSr1-xTiO3 (BST) are presented and analyzed within the framework of a refined treatment of a quasi-harmonic model (QHM) for quantum particles. The QHM involves generalized simple microscopic quantum particles with anharmonic on-site double-Morse-type potential and harmonic interactions. The theory uses the variational principle scheme at finite temperature in the mean-field approximation while taking into account the predominant mass effect, the cell volume effect as well as ferroelectric distortion. The soft-mode frequency and the Ba concentration (x) dependence of the ferroelectric phase transition temperature are analyzed and show good agreement with experimental results throughout the full x range (0 ? x ? 1). It is found that BST is paraelectric below the critical impurity concentration xc = 0.01 with a softening of the soft mode. It becomes ferroelectric above this critical concentration (x ? xc), and as the impurity concentration increases the predominant displacive soft-mode behavior stiffens in the ferroelectric phase with much less softening in crystals indicating a possible phase change at high x. Around x?c = 0.5, Tc deviates gradually from linear behavior with a rather slight round stagnation which might characterize an equilibrium ‘region’ where several ferroelectric phases coexist. The proposed x dependence of the soft-mode behavior indicates that the ferroelectric phase transition is of first order in BST with x > x?c, and of second order for low Ba concentrations (xc ? x < x?c), throughout the tricritical point at x = x?c. Finally, the quantum dynamics of the ferroelectric phase transition and the mode softening are also addressed and discussed, suggesting a net increase of quantum effects with a decrease of x for x ? 0.1, and a dominant Curie-Weiss law for x > 0.1.

Mkam Tchouobiap, S. E.; Dikande, A. M.; Mashiyama, H.

2014-09-01

163

Dielectric and optical behaviors in relaxor ferroelectric Pb(In1/2Nb1/2)1KxTixO3 crystal  

E-print Network

%) single crystal grown by the modified Bridgman method with Pb(Mg1/3Nb2/3)0.71Ti0.29O3 (PMNT29%) seed29% seed crystal, exhibits higher piezoelectric constant d33 (O2000 pC/N) and electromechanical PINT35% (starting composition) single crystal grown with PMNT33% seed crystal, also shows high

164

Structural change in polar nanoregion in alkali niobate added Pb(Zn1/3Nb2/3)0.95Ti0.05O3 single crystal and its effect on ferroelectric properties  

NASA Astrophysics Data System (ADS)

Pb(Zn1/3Nb2/3)0.95Ti0.05O3 (PZNT) single crystals with 5 mol. % alkali niobate such as LiNbO3 (LN), NaNbO3 (NN), and KNbO3 (KN) were fabricated by using a flux method to investigate the effect of A-site cation radius on the structure and ferroelectric properties of PZNT under electric field (E-field). Their structure and properties showed different electric field dependence. Polarization versus electric field and strain versus electric field curves of PZNT-0.05LN showed E-field induced phase transition from a relaxor state to a normal ferroelectric state. However, only relaxor behavior was observed in PZNT-0.05NN and PZNT-0.05KN. The effect of A-site ion doping is attributed to the change in local lattice distortion and polar nano-region. When smaller cation such as Li ion substitutes Pb ion, the off-center displacement of Nb ion stabilizes rhombohedral lattice distortion. They, in turn, facilitate the development of macro-domains under electric field (E-field) in PZNT-0.05LN. In contrast, the substitution of Pb with larger cations such as Ni and K decreases the rhombohedral distortion of PZNT, which leads to the disappearance of unique E-field induced phase transition from rhombohedral to tetragonal phase in PZNT. Therefore, non-linear electrostrictive behavior of relaxor ferroelectrics is found in PZNT-0.05NN and PZNT-0.05KN.

Park, Jong-Sung; Jung, Youngsoo; Lee, Jung-Kun

2012-10-01

165

Fluctuating defects in the incipient relaxor K1 -xLixTaO3 (x =0.02 )  

NASA Astrophysics Data System (ADS)

We report neutron scattering measurements of the structural correlations associated with the apparent relaxor transition in K1 -xLixTaO3 for x =0.02 [KLT(0.02)]. This compound displays a broad and frequency-dependent peak in the dielectric permittivity, which is the accepted hallmark of all relaxors. However, no evidence of elastic diffuse scattering or any soft-mode anomaly is observed in KLT(0.02) [J. Wen et al., Phys. Rev. B 78, 144202 (2008), 10.1103/PhysRevB.78.144202], a situation that diverges from that in other relaxors such as PbMg1 /3Nb2 /3O3 . We resolve this dichotomy by showing that the structural correlations associated with the transition in KLT(0.02) are purely dynamic at all temperatures, having a time scale on the order of ˜ THz. These fluctuations are overdamped, nonpropagating, and spatially uncorrelated. Identical measurements made on pure KTaO3 show that they are absent (within experimental error) in the undoped parent material. They exhibit a temperature dependence that correlates well with the dielectric response, which suggests that they are associated with local ferroelectric regions induced by the Li+ doping. The ferroelectric transition that is induced by the introduction of Li+ cations is therefore characterized by quasistatic fluctuations, which represents a stark contrast to the soft-harmonic-mode-driven transition observed in conventional perovskite ferroelectrics such as PbTiO3. The dynamic, glasslike structural correlations in KLT(0.02) are much faster than those measured in random-field-based lead-based relaxors, which exhibit a frequency scale of order ˜ GHz and are comparatively better correlated spatially. Our results support the view that static random fields give rise to the relaxor phenomena, and that the glasslike dynamics observed here characterize a nascent response.

Stock, C.; Gehring, P. M.; Xu, G.; Lamago, D.; Reznik, D.; Russina, M.; Wen, J.; Boatner, L. A.

2014-12-01

166

Dynamics of nanoscale polarization fluctuations in a uniaxial relaxor.  

PubMed

We have studied neutron diffuse scattering in a Sr(0.61)Ba(0.39)Nb(2)O(6) single crystal by neutron backscattering at sub-?eV energy resolution. We can identify two response components with transverse polarization: an elastic (resolution limited) central peak, which monotonically increases with decreasing temperature, and a quasielastic central peak, having a maximum intensity around the ferroelectric phase transition close to 350 K. In contrast to previous neutron experiments on this and other relaxor materials, we were able to observe a temperature dependence of the characteristic frequency of these fluctuations, obeying the same Vogel-Fulcher law as the dynamic part of the dielectric permittivity of this material. In this way our findings provide a first direct link between the Vogel-Fulcher-type frequency dependence of dielectric permittivity and dynamic nanoscale lattice modulations with a transverse correlation length of about 5-10 unit cells. PMID:25361280

Ondrejkovic, P; Kempa, M; Kulda, J; Frick, B; Appel, M; Combet, J; Dec, J; Lukasiewicz, T; Hlinka, J

2014-10-17

167

Dynamics of Nanoscale Polarization Fluctuations in a Uniaxial Relaxor  

NASA Astrophysics Data System (ADS)

We have studied neutron diffuse scattering in a Sr0.61Ba0.39Nb2O6 single crystal by neutron backscattering at sub-?eV energy resolution. We can identify two response components with transverse polarization: an elastic (resolution limited) central peak, which monotonically increases with decreasing temperature, and a quasielastic central peak, having a maximum intensity around the ferroelectric phase transition close to 350 K. In contrast to previous neutron experiments on this and other relaxor materials, we were able to observe a temperature dependence of the characteristic frequency of these fluctuations, obeying the same Vogel-Fulcher law as the dynamic part of the dielectric permittivity of this material. In this way our findings provide a first direct link between the Vogel-Fulcher-type frequency dependence of dielectric permittivity and dynamic nanoscale lattice modulations with a transverse correlation length of about 5-10 unit cells.

Ondrejkovic, P.; Kempa, M.; Kulda, J.; Frick, B.; Appel, M.; Combet, J.; Dec, J.; Lukasiewicz, T.; Hlinka, J.

2014-10-01

168

Structural Evolving Sequence and Porous Ba6Zr2Nb8O30 Ferroelectric Ceramics with Ultrahigh Breakdown Field and Zero Strain  

E-print Network

Structural Evolving Sequence and Porous Ba6Zr2Nb8O30 Ferroelectric Ceramics with Ultrahigh of relaxor ferroelectric Ba6Zr2Nb8O30 (BZN) ceramics has been investigated and dis- cussed. Porous BZN, which refinements determine the atomic positions and confirm that the porous ceramics has tetragonal tungsten bronze

Cao, Wenwu

169

Efficient Modeling of Ferroelectric Behavior for the Finite Element Analysis of Piezoelectric Actuators  

Microsoft Academic Search

This work proposes a method of efficiently modeling the hysteresis of ferroelectric materials, such that the finite element analysis of complex structures will be possible. Our approach includes the additive combination of a reversible and an irreversible portion of the polarization and strain, respectively. Whereas the reversible parts correspond to the common piezoelectric linear equations, the irreversible parts are modeled

T. Hegewald; E. Leder; M. Kaltenbacher; R. Lerch

2006-01-01

170

Modeling and measurement of hysteresis of ferroelectric actuators considering time-dependent behavior  

Microsoft Academic Search

We present a model for the simulation of ferroelectric hysteresis loops. It is based on the Preisach operator and takes advantage of an analytic weight function for the underlying fundamental switching operators. The five independent parameters describing this weight function are determined for a discoidal piezoceramic actuator by adapting the model output to measurements of the polarization. Further hysteresis simulations,

F. Wolf; A. Sutor; S. J. Rupitsch; R. Lerch

2010-01-01

171

Polar octahedral rotations, cation displacement and ferroelectricity in multiferroic SmCrO3  

NASA Astrophysics Data System (ADS)

Our thorough synchrotron diffraction studies provide a clue on the origin of ferroelectricity in SmCrO3. Careful observation demonstrates that polar order develops in the paramagnetic state. Rietveld refinement of the diffraction data confirms that emergence of polar order is correlated with the structural transformation from centrosymmetric Pbnm to non-centrosymmetric Pna21 space group of the distorted orthorhombic structure. Rotations of polar CrO6 octahedra and Sm displacement are proposed to be correlated with the emergence of polar order, which is extended over a wide temperature range and increases gradually with decreasing temperature. This is consistent with the relaxor behavior as evident from the frequency-dependent dielectric response satisfying the Vogel-Fulcher law. A non-collinear to collinear spin transformation is suggested well below the spin reorientation transition. Appearance of ferroelectricity without any correlation to the antiferromagnetic order in SmCrO3 suggests a new class of ferroelectricity. All-electron full-potential first-principles calculation demonstrates significant Sm-Cr hybridization near the Fermi level, which substantiates the experimental findings.

Ghosh, A.; Dey, K.; Chakraborty, M.; Majumdar, S.; Giri, S.

2014-08-01

172

Ferroelectric and electrical behavior of (Na0.5Bi0.5)TiO3 thin films  

NASA Astrophysics Data System (ADS)

Sodium bismuth titanate (Na0.5Bi0.5)TiO3 (NBT) of perovskite structure is among the best known lead-free piezoelectric/ferroelectric that promises a number of applications in sensors and actuators. However, NBT in thin film form has not been properly investigated, although NBT in bulk ceramic form has been widely studied. In this letter, we report the growth of polycrystalline NBT thin films by radio-frequency magnetron sputtering and their ferroelectric behavior. The NBT thin films exhibit a well-defined hysteresis loop, with a remanent polarization of 11.9?C/cm2 and coercive field of 37.9kV/cm when measured at room temperature. There is a steady decrease of dielectric constant in the range of 650-470 over the frequency range of 10-105Hz. A change in the controlling mechanism of electrical behavior from the grain interior to the grain boundary is observed for the NBT thin film with increasing temperature. Hopping of oxygen vacancies trapped at the grain boundaries is responsible for the high dielectric loss at low frequencies and high dc conductivity observed.

Zhou, Z. H.; Xue, J. M.; Li, W. Z.; Wang, J.; Zhu, H.; Miao, J. M.

2004-08-01

173

Pressure Studies of Quantum Ferroelectrics and Paraelectrics*  

NASA Astrophysics Data System (ADS)

Among the manifestations of quantum fluctuations at ferroelectric phase transitions are different critical exponents, the suppression of the transition temperature, Tc, below its classical value and the ultimate development on a quantum paraelectric state. By shifting Tc with pressure into the quantum regime, we have observed these quantum effects in several ferroelectrics. Emphasis in this presentation will be on Ca- or Ba-doped KTaO3 or KTN crystals. These dopants introduce dipolar defects which strongly influence the susceptibility of the host lattice and enhance long-range dipolar correlations. In a Ca-doped KTN crystal with 2.3at.ferroelectric-to-relaxor crossover and then a crossover to quantum paraelectric state. The susceptibility in the latter state is strongly suppressed by pressure as well as by a biasing dc electric field. The results will be discussed in terms of the physics involved. *Supported by the Division of Materials Sciences, DOE

Samara, G. A.; Venturini, E. L.; Boatner, L. A.

2001-03-01

174

On Annealing and Ferroelectric Behavior in Poly(Vinylidene Fluoride-Trifluoroethylene) Random Copolymers  

NASA Astrophysics Data System (ADS)

Random copolymers of Vinylidene-Fluoride (VF2) and Trifluoroethylene (VF3) having high vinylidene fluoride content are known to crystallize from the melt into the most polar all-trans phase-I crystal form. After poling, these P(VF2-VF3) copolymers have been shown to exhibit significant piezoelectric and pyroelectric response allowing for their use as sensors and actuators. It was also believed that crystallization of these polymers above or below their respective Curie temperatures, (Tc) resulted in the production of a ferroelectric phase. However, studies in our laboratory have shown that samples quenched from the melt to below Tc are not ferroelectric. In order to determine whether or not a ferroelectric phase can be recovered in these materials by subsequent annealing, we performed annealing studies on two of the copolymers: the 80:20 and 73:27 compositions of P(VF2-VF3). As a function of annealing temperature, the remanent polarization, Pr, was observed to increase slowly up to 40° C and then rapidly increase between 40° C and 50° C and then show little increase until just below the Curie temperature range is reached at 90° C, indicating that the copolymers do indeed gradually transform to a ferroelectric state. We also present a series of wide angle x-ray diffraction, (WAXD), results that show the presence of a mixture of phases I and II in the as-quenched material. A clear development of phase I content at the expense of a decrease in phase-II content is observed as the annealing temperature increases.

Christie, M. C.; Scheinbeim, J. I.

2002-03-01

175

E–T phase diagram of the 6.5\\/65\\/35 PLZT incipient ferroelectric  

Microsoft Academic Search

The electric-field–temperature (E–T) phase diagram for lanthanum modified lead zirconate (PLZT) 6.5\\/65\\/35 hot-pressed ceramics was determined by measurements of the quasistatic field-cooled–field-heated (FC\\/FH) dielectric susceptibilities. Approximately linear dependence of the phase transition line between the ergodic relaxor and ferroelectric phases on the bias electric field was found. In zero electric bias field the incipient ferroelectricity is established at nonzero phase

B. Vodopivec; C. Filipi?; A. Levstik; J. Holc; Z. Kutnjak

2004-01-01

176

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

177

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

NASA Astrophysics Data System (ADS)

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

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

2010-09-01

178

Comment on ``Critical behavior of ferroelectric SrTiO318 ''  

NASA Astrophysics Data System (ADS)

Recently reported [C. Filipi? and A. Levstik, Phys. Rev. B 73, 092104 (2006)] and reinforced [J. F. Scott , J. Phys.: Condens. Matter 18, L205 (2006)] critical exponents ?=1.0 and ?=0.5 of the isotope-substituted ferroelectric SrTiO318 are revisited and found to merely describe the mean-field region of this system. Careful evaluation of dielectric susceptibility and second harmonic generation data within the near-critical regime near to Tc?24K yields nonclassic effective exponents, ?=1.65±0.03 and ?=0.21±0.02 . Quantum corrections are relevant, albeit not crucial. Scaling relations and asymptotic criticality are discussed.

Kleemann, Wolfgang; Dec, Jan

2007-01-01

179

Glassy freezing in relaxor ferroelectric lead magnesium niobate  

Microsoft Academic Search

The freezing process in lead magnesium niobate (PMN) has been investigated by measurements of the frequency-dependent complex dielectric constant and its third harmonic component. The linear complex dielectric susceptibility was analyzed by a temperature-frequency plot in order to determine the temperature dependence of the dielectric relaxation spectrum and to identify the freezing temperature. It was found that both the shape

Adrijan Levstik; Zdravko Kutnjak; Cene Filipic; Rasa. Pirc

1998-01-01

180

Structural transformations of PMN relaxor ferroelectric studied by Raman spectroscopy  

NASA Astrophysics Data System (ADS)

We have measured the Raman spectra of a PbMg_1/3Nb_2/3O3 crystal over a very broad range of frequencies (up to 1200 cm-1) and temperatures (1000-100K).The results of the multiple peak decomposition indicate the presence of lattice distortions in their dynamical form even at 1000K.As in the case of KTN [1],lowering the temperature imposes restrictions on the reorientational motion of off-centered ions.The first restrictions appear near the Burns temperature T_d ˜620K, where the slowing down of that motion and the growth of correlations between neighboring off-centered ions causes nucleation of dynamic polar nanoregions and the onset of Fm3m symmetry in the 1:1 ordered areas.Further cooling leads to growing restrictions on the ionic motion and,starting from T_pr ˜350 K,to the appearance of frozen R3m polar nanoregions.By T_do ˜210 K,the formation of the low-temperature disordered R3m phase is mostly complete. This work was supported by DOE grant DE-FG02-00ER45842. [1]O.Svitelskiy,J.Toulouse,J.Phys.Chem.Solids,in print

Svitelskiy, O.; Toulouse, J.; Ye, Z.-G.

2003-03-01

181

Enhanced piezoelectric response in the artificial ferroelectric polymer multilayers  

NASA Astrophysics Data System (ADS)

An actuator with a high piezoelectric response, the ferroelectric polymer multilayer actuator, is described. The ferroelectric polymer multilayers consisting of alternative ferroelectric poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) copolymer and relaxor poly(vinylidene fluoride-trifluoroethylene-chlorofloroethylene) (P(VDF-TrFE-CFE)) terpolymer with different periodicities and fixed total thickness are prepared by the Langmuir-Blodgett technique. Both X-ray diffraction and Raman spectroscopic measurements indicate that the structure of the multilayer with thin alternating layer is similar to that of the ferroelectric copolymer. Compared with that of the copolymer, it is found that the piezoelectric coefficient of the multilayer could be improved by 57%. We attributed the enhanced piezoelectric response of the multilayers to the internal electric fields that arises from the electrostatic couplings between different layers.

Zhao, X. L.; Wang, J. L.; Tian, B. B.; Liu, B. L.; Wang, X. D.; Sun, S.; Zou, Y. H.; Lin, T.; Sun, J. L.; Meng, X. J.; Chu, J. H.

2014-12-01

182

Piezoelectric activity in Perovskite ferroelectric crystals.  

PubMed

Perovskite ferroelectrics (PFs) have been the dominant piezoelectric materials for various electromechanical applications, such as ultrasonic transducers, sensors, and actuators, to name a few. In this review article, the development of PF crystals is introduced, focusing on the crystal growth and piezoelectric activity. The critical factors responsible for the high piezoelectric activity of PFs (i.e., phase transition, monoclinic phase, domain size, relaxor component, dopants, and piezoelectric anisotropy) are surveyed and discussed. A general picture of the present understanding on the high piezoelectricity of PFs is described. At the end of this review, potential approaches to further improve the piezoelectricity of PFs are proposed. PMID:25585387

Li, Fei; Wang, Linghang; Jin, Li; Lin, Dabin; Li, Jinglei; Li, Zhenrong; Xu, Zhuo; Zhang, Shujun

2015-01-01

183

Electromechanical constitutive behavior of various compositions of PZT and PLZT  

NASA Astrophysics Data System (ADS)

A critical step in the design and development of large strain ceramic actuators is the choice of material and composition. The number of available materials is rapidly growing. It now includes the range of soft to hard PZTs, relaxor ferroelectric PLZT and PMN.PT, and electric field induced phase transformation materials PLSnZT. The development of new materials is leading to ever larger strain, but there is a catch that device designers should be aware of. In some systems increased strain is achieved by developing compositions near thermodynamically metastable states, resulting in temperature, stress, and frequency dependence of the strain/electric-field coupling. This work examines the behavior of several compositions of PZT and 8/65/35 PLZT under combined stress and electric field. Additional data is available for a relaxor ferroelectric composition 8/65/35 PLZT (Lynch 1993, 1994). The results show that the addition of dopants to increase hardness reduces the piezoelectric coefficients, but it also increases both the electrical and mechanical yield points. This allows operation over a broader electric field and stress range with less internal heating due to dielectric loss. The materials that produce the largest strain and the least hysteresis in the presence of compressive stress are not necessarily those with the largest piezoelectric d333 coefficients.

Lynch, Christopher S.

1995-05-01

184

The relaxor properties of compositionally disordered perovskites: Ba and Bi-substituted Pb(Zr1-xTix)O3  

Microsoft Academic Search

Dielectric spectroscopy, lattice structure, and thermal properties have revealed the relaxor dielectric response of Ba-substituted lead zirconate\\/titanate (PZT) having the composition (Pb0.71Ba0.29) (Zr0.71Ti0.29)O3 and containing 2 at. % Bi as an additive. The relaxor behavior is attributed to the compositional disorder introduced by the substitution of Ba2+ at the A site and Bi3+\\/5+ at the B site (and possibly A

Samara; George A

2004-01-01

185

Ferroelectric Nanowires  

Microsoft Academic Search

\\u000a Ferroelectric materials are compounds that exhibit a spontaneous electric polarization that can be reoriented by an external\\u000a electric field [1, 2]. Over the last decade, these materials, especially the ferroelectric oxides, have received considerable attention because\\u000a of the fundamental interest in their properties and their potential for a variety of technical applications. The ferroelectric\\u000a oxides typically exhibit a host of

Jonathan E. Spanier; Jeffrey J. Urban; Lian Ouyang; Wan Soo Yun; Hongkun Park

186

Relaxor-based solid solutions for piezoelectric and electrostrictive applications  

NASA Astrophysics Data System (ADS)

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

Alberta, Edward F.

187

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

188

Phase transitions, ferroelectric behavior and second-order nonlinear optics of a new mixed sodium dihydrogen phosphate-arsenate  

NASA Astrophysics Data System (ADS)

Aiming at the development of new proton conducting solids, recent studies of the NaH2PO4·H2O-NaH2AsO4·H2O system have lead to the synthesis of a new compound NaH2(PO4)0.48(AsO4)0.52·H2O (NDAP). Calorimetric studies have confirmed the presence of four reversible phase transitions (abbreviated by PhT), at 257/270 (PhT, IV), 261/290 (PhT, III), 267/301 (PhT, II) and 317/317.5 K (PhT, I) (for cooling/heating processes, respectively). It is shown that the III and IV phase transitions are of a first order type, with a “order-disorder and displacive” character, accompanied by specific dielectric anomalies. The behavior of the dielectric constant ??r and of tan ? shows that, at 272 K, the (PhT, IV) could be ferroelectric-paraelectric. As for the (PhT, III) at 296 K, it leads to a superionic-protonic phase; a jump in the conductivity is associated to this transition with an unusual high value of conductivity 1.07×10-4 ?-1 cm-1 and a low activation energy 0.39 eV (Kh. Jarraya et al.). Quandratic nonlinear (NLO) properties of NDAP powder was confirmed efficiency of the grown crystal by the Kurtz and Perry second harmonic generation (SHG) technique.

Ennaceur, Nasreddine; Jarraya, Khaled; Singh, Anu; Ledoux-Rak, Isabelle; Mhiri, Tahar

2012-03-01

189

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

NASA Astrophysics Data System (ADS)

Some tungsten-bronze ferroelectrics were synthesized and characterized in the BaO-Sm 2O 3-TiO 2-Nb 2O 5 system. Ba 4Sm 2Ti 4Nb 6O 30 and Ba 5SmTi 3Nb 7O 30 had the tetragonal filled tungsten-bronze structure; while Ba 3Sm 3Ti 5Nb 5O 30 consisted of the orthorhombic tungsten-bronze major phase and the BaTi 4O 9 secondary phase. The present dielectric ceramics exhibited relaxor behavior with the maximum temperatures around 185, 285 and 130 °C for Ba 3Sm 3Ti 5Nb 5O 30, Ba 4Sm 2Ti 4Nb 6O 30 and Ba 5SmTi 3Nb 7O 30, respectively. Moreover, Ba 3Sm 3Ti 5Nb 5O 30 exhibited a second possible phase transition around 93 °C.

Zheng, X. H.; Chen, X. M.

2003-02-01

190

Pathways towards ferroelectricity in hafnia  

NASA Astrophysics Data System (ADS)

The question of whether one can systematically identify (previously unknown) ferroelectric phases of a given material is addressed, taking hafnia (HfO2) as an example. Low free energy phases at various pressures and temperatures are identified using a first-principles based structure search algorithm. Ferroelectric phases are then recognized by exploiting group theoretical principles for the symmetry-allowed displacive transitions between nonpolar and polar phases. Two orthorhombic polar phases occurring in space groups Pca21 and Pmn21 are singled out as the most viable ferroelectric phases of hafnia, as they display low free energies (relative to known nonpolar phases), and substantial switchable spontaneous electric polarization. These results provide an explanation for the recently observed surprising ferroelectric behavior of hafnia, and reveal pathways for stabilizing ferroelectric phases of hafnia as well as other compounds.

Huan, Tran Doan; Sharma, Vinit; Rossetti, George A.; Ramprasad, Rampi

2014-08-01

191

Ferroelectric Materials  

NASA Astrophysics Data System (ADS)

Ferroelectric materials offer a wide range of useful properties. These include ferroelectric hysteresis (used in nonvolatile memories), high permittivities (used in capacitors), high piezoelectric effects (used in sensors, actuators and resonant wave devices such as radio-frequency filters), high pyroelectric coefficients (used in infra-red detectors), strong electro-optic effects (used in optical switches) and anomalous temperature coefficients of resistivity (used in electric-motor overload-protection circuits). In addition, ferroelectrics can be made in a wide variety of forms, including ceramics, single crystals, polymers and thin films - increasing their exploitability. This chapter gives an account of the basic theories behind the ferroelectric effect and the main ferroelectric material classes, discussing how their properties are related to their composition and the different ways they are made. Finally, it reviews the major applications for this class of materials, relating the ways in which their key functional properties affect those of the devices in which they are exploited.

Whatmore, Roger

192

ieee transactions on ultrasonics, ferroelectrics, and frequency control, vol. 50, no. 2, february 2003 153 Superthreshold Behavior and Threshold  

E-print Network

ieee transactions on ultrasonics, ferroelectrics, and frequency control, vol. 50, no. 2, february- efactional pressure ranged between 2.2 and 10.4 MPa with either eight or nine acoustic pressure groups

Illinois at Urbana-Champaign, University of

193

Relaxor properties of compositionally disordered perovskites: Ba and Bi-substituted Pb ( Zr1-x Tix ) O3  

Microsoft Academic Search

Dielectric spectroscopy, lattice structure, and thermal properties have revealed the relaxor dielectric response of Ba-substituted lead zirconate\\/titanate (PZT) having the composition (Pb0.71Ba0.29) (Zr0.71Ti0.29)O3 and containing 2at.% Bi as an additive. The relaxor behavior is attributed to the compositional disorder introduced by the substitution of Ba2+ at the A site and Bi3+\\/5+ at the B site (and possibly A site) of

George A. Samara

2005-01-01

194

Non-Debye dielectric dispersion of barium titanate stannate in the relaxor and diffuse phase-transition state  

NASA Astrophysics Data System (ADS)

Frequency dependence Tm(f ) of the permittivity maximum temperature observed in BaTi1-xSnx03, x=0.2 (BTS20), confirms that this composition is close above threshold xc for relaxor behavior in BTS. The low-frequency permittivity carries a ln(1/f )-frequency dependence in the vicinity of Tm, both for x=0.2 and x=0.125relaxor state of BTS.

Mueller, V.; Beige, H.; Abicht, H.-P.

2004-02-01

195

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

196

Dielectric Properties of Relaxor-Like P(VDF-TrFE-CFE) Terpolymer  

Microsoft Academic Search

The dynamic processes in poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) [P(VDF-TrFE-CFE)] terpolymer with a content of 68\\/32\\/9 mol% have been studied by measurements of the temperature and frequency-dependent linear and third-order nonlinear dielectric constants. Analysis of the dielectric response has revealed that dielectric dynamics in this organic system is very similar to behavior observed in various dipolar glasses and relaxors.

B. VODOPIVEC; V. BOBNAR; A. LEVSTIK; Q. M. ZHANG

2004-01-01

197

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

198

Ferroelectric Materials  

Microsoft Academic Search

Ferroelectric materials offer a wide range of useful properties. These include ferroelectric hysteresis (used in nonvolatile memories), high permittivities (used in capacitors), high piezoelectric effects (used in sensors, actuators and resonant wave devices such as radio-frequency filters), high pyroelectric coefficients (used in infra-red detectors), strong electro-optic effects (used in optical switches) and anomalous temperature coefficients of resistivity (used in electric-motor

Roger Whatmore

2007-01-01

199

A high-temperature molecular ferroelectric zn/dy complex exhibiting single-ion-magnet behavior and lanthanide luminescence.  

PubMed

Multifunctional molecular ferroelectrics are exciting materials synthesized using molecular chemistry concepts, which may combine a spontaneous electrical polarization, switched upon applying an electric field, with another physical property. A high-temperature ferroelectric material is presented that is based on a chiral Zn(2+) /Dy(3+) complex exhibiting Dy(3+) luminescence, optical activity, and magnetism. We investigate the correlations between the electric polarization and the crystal structure as well as between the low-temperature magnetic slow relaxation and the optical properties. PMID:25556721

Long, Jérôme; Rouquette, Jérôme; Thibaud, Jean-Marc; Ferreira, Rute A S; Carlos, Luís D; Donnadieu, Bruno; Vieru, Veaceslav; Chibotaru, Liviu F; Konczewicz, Leszek; Haines, Julien; Guari, Yannick; Larionova, Joulia

2015-02-01

200

Orientation dependence of the properties of PZN-4.5%PT relaxor single crystals  

NASA Astrophysics Data System (ADS)

Relaxor ferroelectric PZN-xPT and PMN-xPT single crystals exhibit excellent electromechanical coupling properties that depend on crystallographic orientations. In this study compressive stress and electric field were applied to relaxor single crystals [Pb(Zn1/3Nb2/3)O3]0.955-[PbTiO3]0.045 (PZN-4.5%PT) in a series of crystal orientations between <001> and <111>, and the corresponding strain and electric displacement were measured. It was found that as the angle of the orientation cut is rotated from <001> to <111>, the piezoelectric coefficient d33 drops and hysteresis increases dramatically. A crystal variant based approach was used to model the piezoelectric coefficients and remnant electric displacement. The bipolar electro-mechanical response of these crystals is presented. Observed hysteresis and nonlinear phenomena related to polarization reorientation and phase transitions is discussed. In actuator design and performance control, these results give a guideline regarding appropriate external fields in order to prevent depolarization, heat generation and damage.

Liu, T.; Lynch, C. S.

2005-05-01

201

A micro-Brillouin scattering study of the acoustic properties of PLZT relaxor ceramics  

NASA Astrophysics Data System (ADS)

Acoustic properties of the transparent relaxor ferroelectric ceramics of PLZT-10/65/35 and PLZT-7.6/72/28 were studied by the high-resolution micro-Brillouin scattering technique. The ceramics showed significant softening in the elastic constant and velocity of the longitudinal acoustic (LA) phonon mode, a broad anomaly in the attenuation of the LA mode, and a frequency-dependent dielectric maximum. The temperature dependences of the acoustic anomalies could be explained qualitatively by using electrostrictive coupling, quadratic in order parameter and linear in strain. The interaction between the polar micro regions is more pronounced at some percolation limit below the Burns temperature TB, where the shear deformation develops due to polarization fluctuations, local electrostrictive strain fields and tilting of the oxygen octahedra.

Shabbir, G.; Kojima, S.

2003-11-01

202

Critical Behavior in the Spontaneous Polarization of Ferroelectric Tri-Glycine Sulfate  

NASA Astrophysics Data System (ADS)

The spontaneous polarization P(t) of tri-glycine sulfate was measured in a range 90 K to 323 K by the pyroelectric and the D-E loop method. A non-classical critical-exponent, ?{=}0.45± 0.02 was observed in the region -9.3<\\ln (-t)<-6.8, where t{\\equiv}(T-TC)/TC and TC?322 K. Mean field analyses taking account of electroelastic coupling revealed that a distinct deviation from the classical behavior of P0(t) exists in the region \\ln (-t)?-5. Normalization [P(t)/P0(t)]3 can be approximately expressed by the correction term L{\\cdot}\\psi(L), where L{=}1+3b \\ln t0/2|t| and \\psi(L) is the term for free crystals. In the region -8.3<\\ln (-t)<-6.1, b{=}0.027 and t0{=}0.009 are obtained. The critical amplitude and region, and the correlation lengths were estimated according to Nattermann.

Imai, Kiyoyasu

1980-12-01

203

ieee transactions on ultrasonics, ferroelectrics, and frequency control, vol. 48, no. 2, march 2001 581 Superthreshold Behavior and Threshold  

E-print Network

ieee transactions on ultrasonics, ferroelectrics, and frequency control, vol. 48, no. 2, march 2001 and 160 10-to-11-week-old fe- male Sprague-Dawley rats were randomly divided into two ultrasonic frequency groups, and further randomly divided into seven or eight ultrasonic peak rarefactional pressure groups

Illinois at Urbana-Champaign, University of

204

In situ transmission electron microscopy study of the microstructural origins for the electric field-induced phenomena in ferroelectric perovskites  

NASA Astrophysics Data System (ADS)

Ferroelectrics are important materials due to their extensive technological applications, such as non-volatile memories, field-effect transistors, ferroelectric tunneling junctions, dielectric capacitors, piezoelectric transducers, sensors and actuators. As is well known, the outstanding dielectric, piezoelectric, and ferroelectric properties of these functional oxides originate from their ferroelectric domain arrangements and the corresponding evolution under external stimuli (e.g. electric field, stress, and temperature). Electric field has been known as the most efficient stimulus to manipulate the ferroelectric domains through polarization switching and alignment. Therefore, direct observation of the dynamic process of electric field-induced domain evolution and crystal structure transformation is of significant importance to understand the microstructural mechanisms for the functional properties of ferroelectrics. In this dissertation, electric field in situ transmission electron microscopy (TEM) technique was employed to monitor the real-time evolution of the domain morphology and crystal structure during various electrical processes: (1) the initial poling process, (2) the electric field reversal process, and (3) the electrical cycling process. Two types of perovskite-structured ceramics, normal ferroelectrics and relaxor ferroelectrics, were used for this investigation. In addition to providing the microscopic insight for some well-accepted phase transformation rules, discoveries of some new or even unexpected physical phenomena were also demonstrated. For the initial poling process, microstructural origins for the piezoelectricity development in the three most promising lead-free piezoceramic systems were investigated. For the non-ergodic relaxor ferroelectric compositions ( x = 6% - 9%) in the (1-x)(Bi1/2Na 1/2)TiO3-xBaTiO3 system, well-developed piezoelectricity was realized at poling fields far below the coercive field and phase transition field. Such an unusual behavior is attributed to the electric field-induced irreversible P4bm nanodomains coalescence into thin lamellar domains prior to the phase transition. In the (K0.5 Na0.5)NbO3-based ceramics, as demonstrated by an archetypical polymorphic phase boundary (PPB) composition of 0.948(K 0.5Na0.5)NbO3-0.052LiSbO3, the origin of the excellent piezoelectric performance is due to a tilted monoclinic phase that emerges from the tetragonal and orthorhombic PPB at the poling fields beyond 14 kV/cm. This monoclinic phase, as manifested by the appearance of blotchy domains and 1/2{oeo} superlattice diffraction spots, was determined to possess a Pm symmetry with a 0b+c0 oxygen octahedra tilting and antiparallel cation displacements. For the PPB composition of x = 0.5 in the (1-x)Ba(Zr0.2Ti0.8 )O3-x(Ba0.7Ca0.3)TiO 3 solid solution system, the original multi-domain state was found to transform into a unique single-domain state with orthorhombic symmetry at very moderate poling fields of 3 6 kV/cm. This single-domain state is suggested to be primarily responsible for the observed large piezoelectricity due to its significant elastic softening. In the electrical reversal process, a highly unusual phenomenon of electric field-induced ferroelectric-to-relaxor phase transition was directly observed in a lead-free composition of [(Bi1/2Na1/2)0.95 Ba0.05]0.98La0.02TiO3. It is manifested by the disruption of large ferroelectric domains with long range polar order into polar nanodomains with short range orders when the polarity of electric field is reversed. This observation was further rationalized by a phenomenological model that takes the large difference in kinetics between the phase transition and the polarization reversal processes into account. During the electrical cycling process, the microstructural mechanisms for electric fatigue behaviors of two ceramics were investigated. In 0.7Pb(Mg 1/3Nb2/3)O3-0.3PbTiO3, the frozen domain configuration after 103 cycles is responsible for the pronounced functionality degradation. Both seed inhibition and domain wall pinning mech

Guo, Hanzheng

205

A Mesoscopic Electromechanical Theory of Ferroelectric Films and Ceramics  

E-print Network

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

Bhattacharya, Kaushik

206

Analytical model of the ferroelectric radiation detector  

Microsoft Academic Search

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

J. T. Klopcic; D. L. Swanson

1973-01-01

207

Ferroelectric tunnel memristor.  

PubMed

Strong interest in resistive switching phenomena is driven by a possibility to develop electronic devices with novel functional properties not available in conventional systems. Bistable resistive devices are characterized by two resistance states that can be switched by an external voltage. Recently, memristors-electric circuit elements with continuously tunable resistive behavior-have emerged as a new paradigm for nonvolatile memories and adaptive electronic circuit elements. Employment of memristors can radically enhance the computational power and energy efficiency of electronic systems. Most of the existing memristor prototypes involve transition metal oxide resistive layers where conductive filaments formation and/or the interface contact resistance control the memristive behavior. In this paper, we demonstrate a new type of memristor that is based on a ferroelectric tunnel junction, where the tunneling conductance can be tuned in an analogous manner by several orders of magnitude by both the amplitude and the duration of the applied voltage. The ferroelectric tunnel memristors exhibit a reversible hysteretic nonvolatile resistive switching with a resistance ratio of up to 10(5) % at room temperature. The observed memristive behavior is attributed to the field-induced charge redistribution at the ferroelectric/electrode interface, resulting in the modulation of the interface barrier height. PMID:23039785

Kim, D J; Lu, H; Ryu, S; Bark, C-W; Eom, C-B; Tsymbal, E Y; Gruverman, A

2012-11-14

208

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

NASA Astrophysics Data System (ADS)

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

Pertsev, N. A.; Kohlstedt, H.

2010-11-01

209

Relaxor properties of compositionally disordered perovskites: Ba- and Bi-substituted Pb ( Zr1-x Tix ) O3  

NASA Astrophysics Data System (ADS)

Dielectric spectroscopy, lattice structure, and thermal properties have revealed the relaxor dielectric response of Ba-substituted lead zirconate/titanate (PZT) having the composition (Pb0.71Ba0.29) (Zr0.71Ti0.29)O3 and containing 2at.% Bi as an additive. The relaxor behavior is attributed to the compositional disorder introduced by the substitution of Ba2+ at the A site and Bi3+/5+ at the B site (and possibly A site) of the ABO3 PZT host lattice. Analysis of the results gives clear evidence for the nucleation of polar nanodomains at a temperature much higher than the peak (Tm) in the dielectric susceptibility. These nanodomains grow in size as their correlation length increases with decreasing temperature, and ultimately their dipolar fluctuations slow down below Tm leading to the formation of the relaxor state. The influences of hydrostatic pressure on the dielectric susceptibility and the dynamics of the relaxation of the polar nanodomains were investigated and can be understood in terms of the decrease in the size of the nanodomains with pressure. The influence of dc electrical bias on the susceptibility was also investigated. Physical models of the relaxor response of this material are discussed.

Samara, George A.

2005-06-01

210

Phase transitions in nanoscale ferroelectric structures.  

SciTech Connect

Over decades of effort, investigations of the intrinsic phase transition behavior of nanoscale ferroelectric structures have been greatly complicated by materials processing variations and by the common and uncontrolled occurrence of spacecharge, which interacts directly with the polarization and can obscure fundamental behavior. These challenges have largely been overcome, and great progress in understanding the details of this class of phase transitions has been made, largely based on advances in the growth of high-quality, epitaxial ferroelectric films and in the theory and simulation of ferroelectricity. Here we will discuss recent progress in understanding the ferroelectric phase transition in a particular class of model systems: nanoscale perovskite thin-film heterostructures. The outlook for ferroelectric technology based on these results is promising, and extensions to laterally confined nanostructures will be described.

Streiffer, S. K.; Fong, D. D. (Center for Nanoscale Materials); ( MSD)

2009-01-01

211

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

NASA Astrophysics Data System (ADS)

We have investigated the dielectric response in the terahertz (THz) spectral range of a series of Bi-layered ferroelectrics with Aurivillius structure involving ferroelectric compounds (Bi4Ti3O12,SrBi2Ta2O9,SrBi2Nb2O9) , a relaxor ferroelectric (BaBi2Nb2O9) , and intermediate-type compound (Sr0.5Ba0.5Bi2Ta2O9) . The lowest-frequency polar phonons were studied by means of the time-domain THz transmission spectroscopy in the frequency range 0.1-2THz at temperatures 10-950K . Although previous structural studies suggested a displacive character of the structural phase transitions, no soft-mode anomalies were observed in our THz spectra near Tc in any of the investigated compounds. A gradual and only partial softening of the lowest frequency polar phonon was revealed during heating. Dielectric anomalies near Tc in all the compounds should be caused by slowing down of relaxations, directly observed in some cases below the polar phonon range. The ferroelectric transitions are therefore not classically displacive. In analogy to other relaxor ferroelectrics, existence of dynamic polar clusters is suggested to be in origin of such relaxations. Ferroelectric transitions in such cases are connected with an abrupt freezing and rise of these clusters into domains and the classical division of phase transitions into displacive and order-disorder is no more sufficient.

Nuzhnyy, D.; Kamba, S.; Kužel, P.; Veljko, S.; Bovtun, V.; Savinov, M.; Petzelt, J.; Amorín, H.; Costa, M. E. V.; Kholkin, A. L.; Boullay, Ph.; Adamczyk, M.

2006-10-01

212

Crystal Structure and Relaxor-Type Transition In Praseodymium Doped SBT  

NASA Astrophysics Data System (ADS)

The effects of Pr substitution and ferroelectric response for the Sr1-xPrxBi2Ta2O9 ceramic system were studied. Rietveld refined X-ray diffraction indicates that Pr ion progressively replaces Sr in the A21am space group structure. The solubility of Pr in the solid solution is around 15 %. The replacement induces change in the crystal structure and as consequence dielectric properties are affected. The displacement of TiO6 octahedra with respect to Bi2O2 along the polarization axis decreases as Pr is increased. A notable decrease in the transition temperature (Tm) is observed. With Pr substitution the Tm shifts gradually from ˜305 ^oC to ˜120 ^oC. Apparently, the rotation at the ab-plane (?) as well the octahedral distortion observed are strongly related to the coupling between Tm and x. However, the tilt angle (?) associated to the c-axis don't play an important role as it remains essentially constant. Relaxor type transition is observed as Pr increases due to polar microregions above the nominal ferroelectric transition. Local disorder induced by Pr ion is confirmed by the continuous increase in the diffuseness coefficient according to Isupov's model. Thanks to DGAPA-UNAM and CONACYT for funds through Proj. No. 40604-F, 47714-F, IN116703, IN100903 and to P. Casillas, J. Peralta, M. Sainz.

Mata, Jorge; Duran, Alejandro; Escamilla, Raul; Martinez, Eduardo; Heiras, Jesus; Siqueiros, Jesus

2006-03-01

213

In-situ TEM investigation of the phase transitions in perovskite ferroelectrics  

NASA Astrophysics Data System (ADS)

Ferroelectrics are important materials displaying outstanding dielectric, piezoelectric, and ferroelectric properties and are widely used in capacitors, transducers, actuators, filters, sensors, and random access memories. Direct observation of the dynamic process of thermal and/or electric field-induced phase transitions in ferroelectrics is of great importance in understanding the underlying mechanisms of their peculiar properties. In this work, thermal and electric field in-situ TEM techniques were used to study the dynamic process of antiferroelectric to normal ferroelectric, normal ferroelectric to normal ferroelectric as well as relaxor ferroelectric to normal ferroelectric phase transitions. A thermal in-situ TEM technique was used to study the antiferroelectric to normal ferroelectric phase transition in 0.98PbZrO 3-0.02Pb(Ni1/3Nb2/3)O3 ceramics during heating. The low temperature antiferroelectric phase and intermediate ferroelectric phase are characterized by the 1/4{110}c-type and the 1/2{110}c-type superlattice diffractions, respectively. An incommensurate phase with 1/6.48{110}c satellite diffractions was revealed to exist within a narrow temperature range of 3°C between the antiferroelectric and ferroelectric phases presumably as a result of the competition between two these two types of ordering. The ferroelectric phase is special not only because of its frequency dependence, but also because of its checkerboard type domain morphology. Electric field in-situ TEM and thermal in-situ TEM techniques are used separately to study the FERL ? FERH phase transition in Pb0.99[(Zr0.95Ti 0.05)0.982Nb0.018]O3 ceramics. There appear to be different ferroelectric domains associated with the 1/2{111} c-type superlattice diffraction spots. These two types of domains respond to temperature increase independently. Under the conditions used in this study (thin TEM specimen and field close to <011>c), external electric fields favor the FERH over the FERL phase at room temperature. A cryo electric field in-situ TEM technique was used to study the relaxor ferroelectric to normal ferroelectric phase transition in 0.92Pb(Mg1/3Nb2/3)O3-0.08Pb(Sc 1/2Nb1/2)O3 ceramics. The dynamic phase transition process was observed under TEM for the first time. It is revealed that the electric field-induced relaxor to normal ferroelectric phase transition initiates at grain boundaries. The transition involves the gradual coalescence of polar nanoregions and the successive abrupt formation of large ferroelectric domains. The formed domain/phase walls are roughly along {110} planes. The morphology of the cation ordered domains does not change under applied electric fields. Furthermore, no evidence for strong interactions of these chemical domains with the induced large ferroelectric domains is found in the Sc-doped PMN ceramic.

Qu, Weiguo

214

Time-dependent ferroelectric transition in Pb(1-x)(Zr0.4Ti0.6)(1-x/4)O3 - xLa system  

NASA Astrophysics Data System (ADS)

Ferroelectric transition involves tiny shift of ions within unit cell, thus being intrinsically a very fast process without apparent time-dependence. Contrary to this conventional wisdom, here we report a time-dependent ferroelectric transition, which occurs in hours. The system studied was Pb(1-x)(Zr0.4Ti0.6)(1-x/4)O3 - xLa system with relaxor-forming dopant La3+. The time-dependent ferroelectric transition occurs at the ferroelectric/relaxor crossover composition range of 0.09 < x ? 0.16. In these compositions, in situ Raman spectroscopy and transmission electron microscopy reveal very slow growth of ferroelectric phase. Dielectric measurement shows isothermal kinetics of the transition. The slow ferroelectric transition can be understood as being caused by the slowing-down of the otherwise fast growth of polar nano-domains due to the random local field caused by La3+, so that long time is needed to achieve long-range order macroscopic ferroelectric phase.

Sun, Zhimin; Xue, Dezhen; Wu, Haijun; Ji, Yuanchao; Ding, Xiangdong; Wang, Dong; Yang, Yaodong; Ren, Xiaobing

2013-06-01

215

Size effects in a relaxor: further insights into PMN  

NASA Astrophysics Data System (ADS)

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.

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

2014-07-01

216

Temperature-dependent coherent oscillation in photorefractive relaxor strontium barium  

E-print Network

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

Osnabrück, Universität

217

Electrical Properties of Barium and Zirconium Modified NBT Ferroelectric Ceramics  

NASA Astrophysics Data System (ADS)

Recently a new wave of interest has risen on relaxor ferroelectrics with complex perovskite structure due to their wide use in fabrication of multilayer ceramic capacitors, electrostrictive actuators, and electromechanical transducers. The polycrystalline 0.93(Bi0.5Na0.5)Ba0.07Z0.04T0.96O3 (0.07BNBZT) ceramic material, which is in the vicinity of the morphotropic phase boundary (MPB) has been prepared by using high temperature solid state reaction method. The tolerance factor has been estimated and found to be 0.815. XRD analysis revealed a rhombohedral perovskite type structure. SEM micrographs showed highly dense grains with rectangular shape. The average grain size is found to be 1.51?m. Dielectric studies in the material ha indicated relaxor behaviour with diffuse phase transition. High value of ?m>1958 is found at 1kHz, Tm (phase transition temperature) 335 °C, The diffuseness parameter was established to be 1.60 revealing the relaxor behaviour. Further, to confirm the relaxor behaviour in the material, Vogel-Fulcher (V-F) relation has been used. Estimated V-F parameters are found to be Tf = 138 °C, Ea = 0.080 eV and ?o = 2.32×108 Hz. Cole-Cole analysis has shown a non-Debye type relaxation in the system. Conductivity studies in the material obeyed the Jonscher's power law in frequency range of (45Hz-5MHz) and temperature range of (35 °C-600 °C). The electric conduction in the system may be due to hopping/mobility/ transportation of charge carriers.

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

2011-11-01

218

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

PubMed

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

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

2012-02-29

219

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

NASA Astrophysics Data System (ADS)

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

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

2012-02-01

220

Crystal structure and relaxor-type transition in SrBi(2)Ta(2)O(9) doped with praseodymium.  

PubMed

The effects of Pr substitution in the structure and ferroelectric response for the Sr(1-x)Pr(x)Bi(2)Ta(2)O(9) (SBT-Pr) compound have been studied. Rietveld refinement of the x-ray diffraction patterns indicates that the Pr ion progressively replaces the Sr site in the A 2(1)am space group structure. The solubility of Pr in solid solution is around 15%. The replacement induces a change in the crystal structure and, as a consequence, the dielectric properties are affected. The ferroelectric transition at T(m)?558 K is shifted to lower temperatures, T(m)?413 K for x = 0.15 composition. Apparently, the tilt angle (?) associated with the c-axis does not play an important role since it remains essentially constant. However, the rotation in the ab-plane (?) as well as the octahedral distortion observed are strongly related to the coupling between T(m) and x. A relaxor-type transition is observed as Pr is increased, leading to polar microregions above the nominal ferroelectric transition. The local disorder induced by the Pr ion is confirmed by the continuous increase in the diffuseness coefficient according to Isupov's model. These facts hinder the displacement of the TaO(6) octahedra with respect to Bi(2)O(2) along the polarization axis, decreasing the polarization values. PMID:21690933

Mata, J; Durán, A; Martínez, E; Escamilla, R; Heiras, J; Siqueiros, J M

2006-11-22

221

Crystal structure and relaxor-type transition in SrBi2Ta2O9 doped with praseodymium  

NASA Astrophysics Data System (ADS)

The effects of Pr substitution in the structure and ferroelectric response for the Sr1-xPrxBi2Ta2O9 (SBT-Pr) compound have been studied. Rietveld refinement of the x-ray diffraction patterns indicates that the Pr ion progressively replaces the Sr site in the A 21am space group structure. The solubility of Pr in solid solution is around 15%. The replacement induces a change in the crystal structure and, as a consequence, the dielectric properties are affected. The ferroelectric transition at Tm~558 K is shifted to lower temperatures, Tm~413 K for x = 0.15 composition. Apparently, the tilt angle (?) associated with the c-axis does not play an important role since it remains essentially constant. However, the rotation in the ab-plane (?) as well as the octahedral distortion observed are strongly related to the coupling between Tm and x. A relaxor-type transition is observed as Pr is increased, leading to polar microregions above the nominal ferroelectric transition. The local disorder induced by the Pr ion is confirmed by the continuous increase in the diffuseness coefficient according to Isupov's model. These facts hinder the displacement of the TaO6 octahedra with respect to Bi2O2 along the polarization axis, decreasing the polarization values.

Mata, J.; Durán, A.; Martínez, E.; Escamilla, R.; Heiras, J.; Siqueiros, J. M.

2006-11-01

222

Heterophase fluctuations near Tc in the relaxor ferroelectrics (1-x)Pb(Zn1/3Nb2/3)O3-xPbTiO3 (x =0.09) studied by x-ray diffuse scattering and coherent x-ray scattering  

NASA Astrophysics Data System (ADS)

The paraelectric (PE) to ferroelectric (FE) first-order phase transition of (1-x)Pb(Zn1/3Nb2/3)O3-xPbTiO3 (x =0.09) (Tcc=455 K on cooling) has been studied by the complementary use of x-ray diffuse scattering (XDS) and coherent x-ray scattering (CXS). XDS was mainly used to investigate the FE regions, while CXS was mainly used to investigate the PE regions above Tcc on cooling. The diffuse scattering intensity due to the appearance of FE regions shows a maximum at Tmax=460 K. The diffuse scattering is dynamic in nature and the softening trend changes to a hardening trend at Tmax. This means that the FE instability is maximum at Tmax and therefore the FE regions are well stabilized below Tmax. The spatial autocorrelation function obtained by CXS, corresponding to the texture of PE regions, starts to rapidly change at about Tmax and is most unstable at Tcc. We conclude that a heterophase fluctuation occurs between Tcc and Tmax near the phase transition. The heterophase fluctuation can be expected to correlate to the low-frequency dielectric dispersion and contribute to the phase transition as a precursor phenomenon of the first-order phase transition.

Ohwada, Kenji; Mizuki, Jun'ichiro; Matsushita, Mitsuyoshi; Namikawa, Kazumichi

2014-09-01

223

Ba and Ti co-doped BiFeO3 thin films via a modified chemical route with synchronous improvement in ferroelectric and magnetic behaviors  

NASA Astrophysics Data System (ADS)

A modified chemical route via the layer-by-layer alternative deposition of BaTiO3 and BiFeO3 two compositions followed by the solution processing has been developed to prepare Ba and Ti co-doped multiferroic BiFeO3 thin films. The Ba and Ti co-doped BiFeO3 films crystallize in single perovskite phase and are composed of uniformly distributed grains of tens of nanometers as evidenced by X-ray diffraction and scanning electron microscopy images, respectively. But the films show local composition fluctuation with further high-resolution transmission electron microscope analysis, which leads to increased inner strain and thus a phase transition from R3c to P4mm occurs as Ba and Ti contents reach 50 mol. %. Accompanying the structural phase transition, a saturated P-E hysteresis loop with Pr ˜ 27 ?C/cm2 and Ps ˜ 87 ?C/cm2 and, moreover, a transition from antiferromagnetic to ferromagnetic state with Mr ˜ 1.46 emu/cm3 and Hc ˜ 1000 Oe have been observed. A strain induced structural change is proposed to explain for the observed synchronous enhancement in ferroelectric and magnetic properties, and elastic energy calculation is carried out to verify the viewpoint on magnetic behavior. The modified multiferroic behaviors of Ba, Ti co-doped BiFeO3 film imply an improved magnetoelectric coupling, which makes the material good candidate as memory devices and sensors.

Wang, Yao; Li, Jing; Chen, Jingyi; Deng, Yuan

2013-03-01

224

Ferroelectricity in Strain-Free SrTiO3 Thin Films  

SciTech Connect

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

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

2010-01-01

225

Characteristic temperatures and field effect in KTa1-x NbxO3 relaxor crystals seen via acoustic emission  

NASA Astrophysics Data System (ADS)

[100]-oriented KTa1-xNbxO3 (x=0.32) relaxor ferroelectric crystals have been studied by acoustic emission (AE) count rate dot N in the temperature range from 200?K to 700?K. Burns temperature Td=620?K (dot N = 1.7 -1) and intermediate temperature T*=310?K (dot N = 3.1 -1) as well as both the tetragonal-cubic TT-C=259?K (dot N = 4.0 -1) and orthorhombic-tetragonal TO-T=243?K (dot N = 5.0 -1) phase transition temperatures have been clearly detected. T* is found to be influenced by an external DC electric field E: T* essentially decreases with a slope of approximately -?60?K·cm/kV accompanied with weakening in dot N, as E enhances. The mechanisms of abnormal T*(E) and dot N(T) dependences are discussed.

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

2012-03-01

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

Failure behavior of Pb(Zr0.95Ti0.05)O3 ferroelectric ceramics under shock compression  

NASA Astrophysics Data System (ADS)

PZT 95/5 ferroelectric ceramics have been used in shock-driven pulsed-power supplies for many years; their mechanical failure under shock compression plays an important role in dielectric breakdown. Shock experiments have been conducted to understand such failure by measuring the velocity of the free surface or the PZT/sapphire interface. Results confirm that delayed failure exists in PZT 95/5 before dynamic yielding at 2.4 GPa; multipoint measurements indicate that the failure layer in PZT 95/5 was not a plane but a rough front. The delay time and velocity of this layer had been determined by measuring samples of varying thicknesses at fixed pressure; results indicate that this velocity is the same as the shock-wave speed and the delay time decreases with increasing shock stress. At a shock stress of 4.9 GPa, the delay time falls to zero and a ramp wave is observed. This kind of failure is a new phenomenon in electric breakdown of PZT 95/5 under shock compression.

Zhang, Fuping; He, Hongliang; Liu, Gaomin; Liu, Yusheng; Yu, Yin; Wang, Yonggang

2013-05-01

228

2280 ieee transactions on ultrasonics, ferroelectrics, and frequency control, vol. 53, no. 12, december 2006 KTa0.6Nb0.4O3 Ferroelectric Thin Film Behavior  

E-print Network

the relationships be- tween 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.6Nb0.4O3 (KTN) materials, which have, like BST, a crystal structure of the perovskite type [3

Brest, Université de

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

Effect of Ba on ferroelectric and piezoelectric properties of the PLZT (1.2/55/45) system  

NASA Astrophysics Data System (ADS)

Ferroelectric Pb0.982-zLa0.0120.006Baz(Zr0.55Ti0.45)O3 (PLZT; z = 0-6 mol%) ceramic compositions were fabricated by a mixed-oxide method. X-ray diffraction studies of sintered ceramics indicate the coexistence of rhombohedral and tetragonal phases in the 5 mol% Ba-doped PLZT composition. Grain growth is inhibited with increasing Ba concentration in the PLZT system as evidenced by scanning electron micrographs. Dielectric constant and dielectric loss as a function of temperature suggest that rt and tan ? are increased up to compositions containing 4 and 5 mol% Ba, respectively. The dielectric maximum (Tc) decreased to 4 mol% Ba and gradually increased to 6 mol% Ba, whereas, with increasing Ba concentration in the PLZT system, the Curie temperature (TC) decreased from the composition with no Ba to that with 6 mol% Ba. Relaxor behavior as a function of temperature and frequency was studied over the composition series. As the Ba concentration increased, the coercive field (Ec) showed a gradual enhancement. Remanent (Pr) and spontaneous (Ps) polarizations decreased to the 5 mol% Ba composition. Piezoelectric charge coefficient (d33), piezoelectric planar coupling coefficient (kp) and piezoelectric thickness coupling coefficient (kt) increased to the 4 mol% Ba composition, which are potential compositions for sensor and actuator applications.

Koduri, Ramam; Salinas Hermosilla, Luis

2006-06-01

231

Size-induced diffuse behavior in Pb0.89La0.11Zr0.40Ti0.60O3 nanocrystalline ferroelectric ceramics  

NASA Astrophysics Data System (ADS)

The Pb1-xLaxZryTi1-yO3 system is a perovskite ABO3 structured material which presents ferroelectric properties and has been used as capacitors, actuators, transducers and electro-optic devices. In this paper, we describe the synthesis and the characterization of Pb0.89La0.11Zr0.40Ti0.60O3 (PLZT11) nanostructured material. The precursor polymeric method and the spark plasma sintering technique were respectively used to prepare ceramic samples. In order to compare the effect of grain size, microcrystalline PLZT11 ceramic samples were also prepared. PLZT11 samples were characterized by X-ray diffraction technique which results show a reduction on the degree of tetragonality as the average grain size decreases. Moreover, the grain size decrease to a nanometer range induces a diffuse behavior on the dielectric permittivity curves as a function of the temperature and a reduction on the dielectric permittivity magnitude. Furthermore, the large number of grain boundaries due to the nanometer size gives rise to a dielectric anomaly.

Mesquita, Alexandre; Godart, Claude; Michalowicz, Alain; Mastelaro, Valmor R.

2012-09-01

232

Ferroelectric electron holography.  

PubMed

Ferroelectrics are increasingly important as materials in semiconductor technology, e.g. for building non-volatile memory chips. For optimisation of the properties of such devices, there is an urgent need for methods, which analyse the ferroelectric properties at nanometer scale. Furthermore, the basic understanding of the interaction of ferroelectrics with electrons in the transmission electron microscopy is still incomplete. It is shown that electron holography offers a promising way to understand and investigate ferroelectrics in the electron microscope. PMID:12492231

Lichte, Hannes; Reibold, Marianne; Brand, Karin; Lehmann, Michael

2002-12-01

233

Imaging three-dimensional polarization in epitaxial polydomain ferroelectric thin films  

E-print Network

the macroscopic behavior of ferroelectric materials for applica- tions in nonvolatile memories, sensors this technique to reconstruct the three-dimensional distribution of polarization within domains of ferroelectric in ferroelectric films is a mechanism of strain energy relaxation.10 It is especially important to visualize

Alpay, S. Pamir

234

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

235

The relaxor properties of compositionally disordered perovskites: Ba- and Bi-substituted Pb(Zr1-xTix)O3.  

SciTech Connect

Dielectric spectroscopy, lattice structure, and thermal properties have revealed the relaxor dielectric response of Ba-substituted lead zirconate/titanate (PZT) having the composition (Pb0.71Ba0.29) (Zr0.71Ti0.29)O3 and containing 2 at. % Bi as an additive. The relaxor behavior is attributed to the compositional disorder introduced by the substitution of Ba2+ at the A site and Bi3+/5+ at the B site (and possibly A site) of the ABO3 PZT host lattice. Analysis of the results gives clear evidence for the nucleation of polar nanodomains at a temperature much higher than the peak (Tm) in the dielectric susceptibility. These nanodomains grow in size as their correlation length increases with decreasing temperature, and ultimately their dipolar fluctuations slow down below Tm leading to the formation of the relaxor state. The influences of hydrostatic pressure on the dielectric susceptibility and the dynamics of the relaxation of the polar nanodomains were investigated and can be understood in terms of the decrease in the size of the nanodomains with pressure. The influence of dc electrical bias on the susceptibility was also investigated. Physical models of the relaxor response of this material are discussed.

Samara, George A.

2004-09-01

236

The Role of Proton for the Effect of Interlayer on Ferroelectric Behavior of Poly(vinylidene fluoride-trifluoroethylene) Copolymer Ultrathin Films  

Microsoft Academic Search

A functional interlayer, poly(3,4-ethylene dioxythioohene)-poly(styrene sulfonic) acid, is introduced as a buffer layer between the metal electrodes of a capacitor composed of ferroelectric poly(vinylidene fluoridetrifluoroethylene) copolymer ultrathin film. The sandwiched structure shows prominent ferroelectric properties even as the thickness of P(VDF-TrFE) film is reduced to 50 nm and the fatigue property is also improved tremendously. We demonstrate that the proton

H. S. Xu; Y. N. Zhang; X. L. Zhang; Y. P. Ma

2011-01-01

237

Scaling Behavior of Ferroelectric Hysteresis Loop in 63PbTiO3–37BiScO3 Bulk Ceramic  

Microsoft Academic Search

The ferroelectric hysteresis loops of 63PbTiO3–37BiScO3 bulk ceramics were measured under sinusoidal electric fields over a frequency range of 1 Hz–100 Hz and amplitude range of 10 kV\\/cm–50 kV\\/cm. Scaling relation of ferroelectric hysteresis loops area ?A? versus frequency f and the amplitude of field E0 for the saturated loops is , while the scaling relation for the unsaturated loops

Gang Yu; Xuefeng Chen; Genshui Wang; Xianlin Dong

2010-01-01

238

The effective pyroelectric and thermal expansion coefficients of ferroelectric ceramics  

E-print Network

The effective pyroelectric and thermal expansion coefficients of ferroelectric ceramics JiangYu Li ceramics in terms of their microstructural information. The overall behaviors of ferroelectric ceramics be induced in an originally isotropic, thus non-pyroelectric ceramic composed of randomly oriented

Li, Jiangyu

239

X-Ray Absorption Fine Structure Applied to Ferroelectrics  

NASA Astrophysics Data System (ADS)

This chapter is devoted to explaining the foundation and merits of the application of synchrotron radiation for studying the X-ray absorption fine structure (XAFS) in ferroelectric materials. XAFS in the local order allows the follows: determining the oxidation states, interatomic distances, Debye-Waller factors and the coordination number of atoms at the first few shells around the absorbing atom, up to 0.5 nm. The text explains the features of the photoelectric effect, as well as its relationship with the absorption edges of each element. Applying the Fermi's Golden Rule, it is explained that the fine structure of absorption edge spectra is the result of the interference of the photoelectron single- and multiple-scattering. This gives rise to the effects of X-ray Absorption Near Edge Structure (XANES) and Extended X-ray Absorption Fine Structure (EXAFS). The content includes significant effects for the study of ferroelectric materials in XANES: energy shift of the edge position, pre-edge transitions and white-lines. Subsequently, the experimental methods and EXAFS spectra processing, by both empirical methods and theoretical models with multiple scattering paths, are presented. Finally, we offer some works representing XAFS applied to ferroelectrics, from the explanation of the displacive or order-disorder nature of the materials PbTiO3 and BaTiO3, to those dedicated to relaxors and Aurivillius oxides.

Cabrera, Maria Elena Montero

240

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

NASA Astrophysics Data System (ADS)

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 behavior arises from the interface formed between BiFeO3 and ZnO. As expected, the diodelike and resistive hysteresis behavior are weakened and almost disappeared in the case of BiFeO3/ZnO/BiFeO3 and ZnO/BiFeO3/ZnO, where the two interfaces are equal and opposite to each other. The interface-limited Fowler-Nordheim tunneling in the high electric field region is demonstrated to involve in the formation of resistive hysteresis.

Wu, Jiagang; Wang, John

2010-11-01

241

The three characteristic Temperatures of Relaxor Dynamics and their Meaning  

NASA Astrophysics Data System (ADS)

In this report, we compare the temperature evolution of several physical properties of the relaxor systems PZN, PMN and KTN. We show that three rather than two characteristic temperatures can be identified, TB, T* and Tf, and discuss their meaning in light of dielectric, Raman and neutron scattering experimental results.

Toulouse, Jean

2009-03-01

242

A light-modified ferroelectric resistive switching behavior in Ag/BaMoO4/FTO device at ambient temperature  

NASA Astrophysics Data System (ADS)

BaMoO4 powder was prepared by a facile hydrothermal synthesis. And the BaMoO4/FTO device was fabricated by a spin-coated method, in which the thickness of BaMoO4 layer is about 20 ?m. The bipolar resistive switching effect has been observed in Ag/BaMoO4/FTO device. Moreover, the resistive switching effect of the device is greatly improved by white light irradiation. The resistive switching behavior is explained by the polarization reversal that changes the charge distribution and modulates the Schottky barriers.

Zhao, W. X.; Sun, B.; Liu, Y. H.; Wei, L. J.; Li, H. W.; Chen, P.

2014-12-01

243

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

SciTech Connect

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

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

2014-03-31

244

Structural Behavior of the Four-Layer Aurivillius-Phase Ferroelectrics SrBi 4Ti 4O 15 and Bi 5Ti 3FeO 15  

Microsoft Academic Search

Rietveld refinement of powder neutron diffraction data has been used to study the crystal structures of the four-layer Aurivillius-phase ferroelectrics Bi5Ti3FeO15 (at 25°C) and SrBi4Ti4O15 (at a series of temperatures up to 800°C). At 25°C both materials adopt the polar orthorhombic space group A21am, in common with two-layer analogues such as SrBi2Ta2O9. At temperatures well above the ferroelectric Curie temperature

Charles H. Hervoches; Alan Snedden; Richard Riggs; Susan H. Kilcoyne; Pascal Manuel; Philip Lightfoot

2002-01-01

245

Relaxor fluorinated polymers: Novel applications and recent developments  

Microsoft Academic Search

A new class of ferroelectric polymers, i.e., the terpolymers of P(VDF-TrFE-CFE) and P(VDF-TrFE-CTFE), was developed from the normal ferroelectric PVDF polymer by employing proper defect modifications which eliminate detrimental effects associated with a normal first order F-P transition while maintaining high material responses. The introduction of the third monomer into the polymer chain serves to interrupt the ferroelectric domains, thereby

F. Bauer; Qiming Zhang

2008-01-01

246

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

247

Ferroelectric materials for electromechanical transducer applications  

Microsoft Academic Search

This paper explores the special characteristics of ferroelectric materials which make them highly suitable for application as both sensors and actuators in electromechanical (smart) systems. The domain structure which gives the possibility to impart a polar axis in a randomly axed polycrystal ceramic is essential for piezoelectricity, but all electromechanical behavior may be traced ultimately to the electrostrictive coupling between

Leslie Eric Cross

1996-01-01

248

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

249

Ferroelectric liquid crystal display  

NASA Technical Reports Server (NTRS)

A ferroelectric liquid crystal display device employs capacitance spoiling layers to minimize unneeded capacitances created by crossovers of X and Y address lines and to accurately define desired capacitances. The spoiler layers comprise low dielectric constant layers which space electrodes from the ferroelectric at crossover points where capacitance is not needed for device operation.

York, Paul K. (Inventor)

1977-01-01

250

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

251

Study on dielectric properties of PMN-PZN-PT ferroelectric relaxor ceramics  

Microsoft Academic Search

The influence of additions and processing on the microstructure and properties of PMN-PZN-PT ceramics was studied. Experimental results showed that the DC bias character of PMN-based ceramics doped with PZN could be improved; proper excess MgO is advantageous to inhibiting the pyrochlore phase and increasing the dielectric constant. Dielectric loss could be decreased by adding MnO2. It was also found

Zhilun Gui; Longtu Li; Xiaowen Zhang

1991-01-01

252

A numerical analysis of relaxor ferroelectric multilayered actuators and 2-2 composite arrays  

Microsoft Academic Search

Nonlinear, quasi-static finite-element calculations are performed for multilayered, electrostrictive, ceramic actuators. Both a stand-alone device and an array of devices embedded in a 2-2 composite are studied. The numerical model is based on a fully coupled constitutive law for electrostriction which uses strain and polarization as independent state variables. This law accounts for the stress dependence of the ceramic`s dielectric

C. L. Hom; N. Shankar

1995-01-01

253

Switching spectroscopic measurement of surface potentials on ferroelectric surfaces via an open-loop Kelvin probe force microscopy method  

NASA Astrophysics Data System (ADS)

We report a method for switching spectroscopy Kelvin probe force microscopy (SS-KPFM). The method is established as a counterpart to switching spectroscopy piezoresponse force microscopy (SS-PFM) in Kelvin probe force microscopy. SS-KPFM yields quantitative information about the surface charge state during a local bias-induced polarization switching process, complementary to the electromechanical coupling properties probed via SS-PFM. Typical ferroelectric samples of a Pb-based relaxor single crystal and a BiFeO3 thin film were investigated using both methods. We briefly discuss the observed surface charging phenomena and their influence on the associated piezoresponse hysteresis loops.

Li, Qian; Liu, Yun; Wang, Danyang; Withers, Ray L.; Li, Zhenrong; Luo, Haosu; Xu, Zhuo

2012-12-01

254

Ferroelectric switching of elastin  

PubMed Central

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

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

2014-01-01

255

Phase transition hysteresis and anomalous Curie-Weiss behavior of ferroelectric tetragonal tungsten bronzes Ba2RETi2Nb3O15:RE=Nd,Sm  

NASA Astrophysics Data System (ADS)

The ferroelectric tetragonal tungsten bronze (TTB) phases, Ba2RETi2Nb3O15:RE=Nd,Sm, were prepared by low temperature solvothermal synthesis. The permittivity versus temperature data of sintered ceramics show two unusual features: first, a hysteresis of 50-100 °C between values of the Curie temperature Tc on heat-cool cycles and second: a huge depression in the Curie-Weiss temperature T0. Both effects are attributed to the complex nature of their TTB-related crystal structures with different superstructures above and below Tc and the difficulty in nucleating ferroelectric domains on cooling through Tc. Several factors may contribute to the latter difficulty: first, the structures contain two sets of crystallographic sites for the "active" Ti, Nb ions; second, the distribution of Ti and Nb over these two sets of sites is not random but partially ordered; and third, below Tc a weak commensurate superstructure perpendicular to the polar c&barbelow; axis is present, but above Tc a weak incommensurate superstructure in a similar orientation is present. Hence the formation of the ferroelectric structure on cooling requires both nucleation of polar domains involving two sets of cation sites and structural change from an incommensurate to a commensurate supercell.

Prades, Marta; Beltrán, Héctor; Masó, Nahum; Cordoncillo, Eloisa; West, Anthony R.

2008-11-01

256

Structural Behavior of the Four-Layer Aurivillius-Phase Ferroelectrics SrBi 4Ti 4O 15 and Bi 5Ti 3FeO 15  

NASA Astrophysics Data System (ADS)

Rietveld refinement of powder neutron diffraction data has been used to study the crystal structures of the four-layer Aurivillius-phase ferroelectrics Bi5Ti3FeO15 (at 25°C) and SrBi4Ti4O15 (at a series of temperatures up to 800°C). At 25°C both materials adopt the polar orthorhombic space group A21am, in common with two-layer analogues such as SrBi2Ta2O9. At temperatures well above the ferroelectric Curie temperature (i.e., at temperatures of 650°C and above, with Tc?550°C) SrBi4Ti4O15 transforms to the centrosymmetric tetragonal space group I4/mmm. However, there is good evidence from the raw diffraction data of a very subtle intermediate paraelectric orthorhombic phase, of Amam symmetry, in the region 550>650°C. The distortion in the ferroelectric phase can be traced to displacements of the cations in the A site of the perovskite block, with cooperative tilting of the BO6 octahedra. The nature of the octahedral tilt system, cation disorder at the perovskite A and B sites, and the phase transition sequence in SrBi4Ti4O15, which parallels that found in SrBi2Ta2O9, are discussed.

Hervoches, Charles H.; Snedden, Alan; Riggs, Richard; Kilcoyne, Susan H.; Manuel, Pascal; Lightfoot, Philip

2002-03-01

257

Pressure as a probe of ferroelectric properties: Quantum regime  

NASA Astrophysics Data System (ADS)

Quantum fluctuations can strongly influence the low temperature response of a system near a structural phase transition. Among the manifestations of quantum fluctuations at ferroelectric phase transitions are the suppression of the transition temperature, Tc, below its classical value, the emergence of a special critical point—the quantum displacive limit where Tc=0 K, and the ultimate development of a quantum paraelectric state. To study these quantum effects as well as the crossover from the classical to the quantum regime, it is necessary to shift Tc to the appropriate low-temperature range. This is conventionally done by chemical substitution, but we find that high pressure is a "cleaner" variable. After a brief summary of earlier theoretical and experimental work, results on KTaO3 and KTN crystals doped with ˜0.05 at % Ca or Ba are presented. The addition of these two dopants introduces dipolar defects into the KTaO3 lattice which strongly enhance the dielectric susceptibility of the host lattice in the quantum regime. In a Ca-doped KTN crystal with 2.3 at % Nb, pressure induces a crossover from normal ferroelectric to a relaxor state which on further increase in pressure crosses over to a quantum paraelectric phase. With Ba-doping KTaO3 remains a quantum paraelectric. Because the characteristic energies are small in the quantum regime, the properties are very strongly dependent on pressure and biasing electric fields. The results are discussed in terms of the physics involved.

Samara, G. A.; Boatner, L. A.

2001-08-01

258

Temperature evolution of the relaxor dynamics in Pb ( Zn1/3 Nb2/3 ) O3 : A critical Raman analysis  

NASA Astrophysics Data System (ADS)

At the heart of the relaxor behavior lies the development of mesoscopic or intermediate range order and the low frequency or relaxation dynamics associated with it. To investigate this development, we have measured the Raman spectra of a Pb(Zn1/3Nb2/3)O3 (PZN) single crystal over a wide temperature range from 1000Kto150K . The spectra are analyzed using several different physical models, focusing particularly on the low frequency part. Both relaxation and coupled phonon dynamics are identified. The evolution of the relaxor dynamics is marked by three characteristic temperatures, Burns temperature, TB?650K , and two other temperatures, Td?470K and Tf?340K , which together define four major ranges. Combining the fitting results from the Raman spectra and other experimental results in PZN, we describe the relaxor dynamics in these four ranges, in terms of the strength and lifetime of the correlations between off-center ions. Relating the dynamics observed in PZN to that in KTa1-xNbxO3 (KTN), we develop a microscopic model based on the coexistence of a fast and a slow motion of the off-center Pb and Nb ions which accounts for both types of dynamics (coupled phonon and relaxational) between TB and Tf , and show evidence for a series of local phase transitions taking place below Td .

Toulouse, J.; Jiang, F.; Svitelskiy, O.; Chen, W.; Ye, Z.-G.

2005-11-01

259

Ferroelectric Light Control Device  

NASA Technical Reports Server (NTRS)

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

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

2008-01-01

260

Ferroelectric-based microactuators  

Microsoft Academic Search

This paper reviews the current state of ferroelectric-based microactuators. The advantages of ferroelectric-based microactuation are considered. Several actuator concepts are discussed including unimorph-based cantilever actuators, membrane-based micropumps, linear positioning actuators using folded geometries of cascaded elementary actuators for both in-plane and out-of-plane displacements, linear stepper motors using inch-worm geometries, and ultrasonic-based micromotors. Optimistic, order-of-magnitude estimates of actuator performance are given

William P. Robbins

1995-01-01

261

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

SciTech Connect

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

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

2014-05-15

262

INVESTIGATION OF FERROELECTRICITY AND PIEZOELECTRICITY IN FERROELECTRIC THIN FILM CAPACITORS  

E-print Network

INVESTIGATION OF FERROELECTRICITY AND PIEZOELECTRICITY IN FERROELECTRIC THIN FILM CAPACITORS USING-MADISON 2006 #12;i ABSTRACT Ferroelectric materials have a wide range of applications in nonvolatile memory devices, sensors, and actuators due to their properties such as remnant polarization and piezoelectricity

Evans, Paul G.

263

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

264

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

265

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

266

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. 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

267

Large magnetocapacitance in electronic ferroelectric manganite systems  

SciTech Connect

We have observed a sizable positive magnetocapacitance (?5%–90%) in perovskite Pr{sub 0.55}Ca{sub 0.45}MnO{sub 3} and bilayer Pr(Sr{sub 0.1}Ca{sub 0.9}){sub 2}Mn{sub 2}O{sub 7} system under 5?T magnetic field across 20–100?K below the magnetic transition point T{sub N}. The magnetodielectric effect, on the other hand, exhibits a crossover: (a) from positive to negative for the perovskite system and (b) from negative to positive for the bilayer system over the same temperature range. The bilayer Pr(Sr{sub 0.1}Ca{sub 0.9}){sub 2}Mn{sub 2}O{sub 7} system exhibits a sizable anisotropy as well. We have also noticed the influence of magnetic field on the dielectric relaxation characteristics of these systems. These systems belong to a class of improper ferroelectrics and are expected to exhibit charge/orbital order driven ferroelectric polarization below the transition point T{sub CO}. Large magnetocapacitance in these systems shows a typical multiferroic behavior even though the ferroelectric polarization is small in comparison to that of other ferroelectrics.

Chowdhury, Ujjal; Goswami, Sudipta; Bhattacharya, Dipten, E-mail: dipten@cgcri.res.in [Nanostructured Materials Division, CSIR-Central Glass and Ceramic Research Institute, Kolkata 700032 (India); Midya, Arindam; Mandal, P. [Experimental Condensed Matter Physics, Saha Institute of Nuclear Physics, Kolkata 700064 (India); Das, Pintu [Institute of Physics, J.W. Goethe University, D-60438 Frankfurt (Germany); Mukovskii, Ya. M. [National Research Technological University, “MISiS,” Moscow 119049 (Russian Federation)

2013-11-21

268

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

269

A ferroelectric memristor.  

PubMed

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. PMID:22983431

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

270

Electric field induced metastable ferroelectric phase and its behavior in (Pb, La)(Zr, Sn, Ti)O{sub 3} antiferroelectric single crystal near morphotropic phase boundary  

SciTech Connect

Antiferroelectric (AFE) (Pb, La)(Zr, Sn, Ti)O{sub 3} (PLZST) single crystal with composition near morphotropic phase boundary has been grown and studied. X-ray diffraction analysis and electrical properties reveal coexistence of antiferroelectric/ferroelectric (FE) phases, with the AFE phase dominated at room temperature. Temperature-dependent polarization and strain measurements indicate that the AFE phase can be induced into a metastable FE phase by electric field. The FE phase can be maintained in a wide temperature range above room temperature and recovers to AFE phase around a critical temperature of 90?°C, accompanied with remarkable change in field-induced strain. The strain at 90?°C (?0.50%) is ten times larger than that at room temperature (?0.04%), which makes the PLZST single crystal a promising candidate for thermal switch and actuator application.

Li, Yuanyuan; Li, Qiang, E-mail: qiangli@mail.tsinghua.edu.cn; Yan, Qingfeng; Gao, Jinghan; Zhuo, Fangping [Department of Chemistry, Tsinghua University, Beijing 100084 (China); Cao, Wenwu [Condensed Matter Science and Technology Institute, Harbin Institute of Technology, Harbin, Heilongjiang 150080 (China); Materials Research Institute, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Xi, Xiaoqing; Zhang, Yiling; Chu, Xiangcheng [State Key Laboratory of New Ceramics and Fine Processing, Tsinghua University, Beijing 100084 (China)

2014-02-03

271

Electric field induced metastable ferroelectric phase and its behavior in (Pb, La)(Zr, Sn, Ti)O3 antiferroelectric single crystal near morphotropic phase boundary  

NASA Astrophysics Data System (ADS)

Antiferroelectric (AFE) (Pb, La)(Zr, Sn, Ti)O3 (PLZST) single crystal with composition near morphotropic phase boundary has been grown and studied. X-ray diffraction analysis and electrical properties reveal coexistence of antiferroelectric/ferroelectric (FE) phases, with the AFE phase dominated at room temperature. Temperature-dependent polarization and strain measurements indicate that the AFE phase can be induced into a metastable FE phase by electric field. The FE phase can be maintained in a wide temperature range above room temperature and recovers to AFE phase around a critical temperature of 90 °C, accompanied with remarkable change in field-induced strain. The strain at 90 °C (˜0.50%) is ten times larger than that at room temperature (˜0.04%), which makes the PLZST single crystal a promising candidate for thermal switch and actuator application.

Li, Yuanyuan; Cao, Wenwu; Li, Qiang; Yan, Qingfeng; Gao, Jinghan; Zhuo, Fangping; Xi, Xiaoqing; Zhang, Yiling; Chu, Xiangcheng

2014-02-01

272

Monte Carlo simulation on rotation of ferroelectric polarization by rotating magnetic field in conical-spin-ordered multiferroics  

Microsoft Academic Search

To understand the rotation phenomenon of ferroelectric polarization (P) controlled by a magnetic field (h), which is currently of great interest in experiments, the variation of the magnetic and ferroelectric behaviors under rotating h are investigated by Monte Carlo simulation on a three-dimensional spinel lattice with classical Heisenberg spins. The anisotropic behaviors are observed for the different paths in which

Xiaoyan Yao; Qichang Li

2009-01-01

273

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

NASA Astrophysics Data System (ADS)

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

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

274

Structures, electrical properties, and leakage current behaviors of un-doped and Mn-doped lead-free ferroelectric K{sub 0.5}Na{sub 0.5}NbO{sub 3} films  

SciTech Connect

Lead-free ferroelectric un-doped and doped K{sub 0.5}Na{sub 0.5}NbO{sub 3} (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, E-mail: l.y.wang@mail.xjtu.edu.cn, E-mail: wren@mail.xjtu.edu.cn; Ren, Wei, E-mail: l.y.wang@mail.xjtu.edu.cn, E-mail: wren@mail.xjtu.edu.cn; Shi, Peng; Wu, Xiaoqing [Electronic Material Research Laboratory, Key Laboratory of the Ministry of Education and International Center for Dielectric Research, Xi'an Jiaotong University, Xi'an 710049 (China)

2014-01-21

275

Cryogenic temperature relaxor-like dielectric responses and magnetodielectric coupling in Aurivillius Bi5Ti3FeO15 multiferroic thin films  

NASA Astrophysics Data System (ADS)

Dielectric responses and magnetodielectric (MD) behavior of Aurivillius Bi5Ti3FeO15 multiferroics were systemically studied at cryogenic temperatures. Dielectric anomaly at ˜145 K was found by the temperature dependent dielectric spectroscopy, and relaxor-like relaxation dynamics was further confirmed unambiguously. Besides the two abnormal MD transitions at about 98 K and 220 K, remarkable MD couplings were observed near relaxation peak over the whole frequency range of 102-106 Hz. Finally, the possible mechanisms of the relaxation and MD properties were discussed in association with the occurrence of local Fe-O nano-clusters because of the antisite disorder defects in Aurivillius multiferroic phases.

Bai, Wei; Yin, Wenhao; Yang, Jing; Tang, Kai; Zhang, Yuanyuan; Lin, Tie; Meng, Xiangjian; Duan, Chun-Gang; Tang, Xiaodong; Chu, Junhao

2014-08-01

276

Relaxor single crystals in the (Bi1/2Na1/2)1-xBaxZryTi1-yO3 system exhibiting high electrostrictive strain  

NASA Astrophysics Data System (ADS)

Single crystals have been grown in the (Bi1/2Na1/2)1-xBaxZryTi1-yO3 perovskite system by a self-flux method over the range of compositions y=0.04 and x=0.06-0.012. Rhombohedral (x?0.08) and tetragonal phase (x?0.09) crystals have been obtained that do not show polarization or field-induced strain hysteresis characteristics of a ferroelectric. However, a frequency-dispersive dielectric response characteristic of a relaxor ferroelectric, and predominantly electrostrictive actuation, is observed across the range of compositions tested, with Q11=(2.8-3.3)×10-2m4/C2. Due to induced polarizations that do not saturate at fields beyond 50 kV/cm, high electrostrictive strains are obtained. Rhombohedral phase crystals exhibit d33 up to 1180 pC/N and strains of S3=0.3% before electrical breakdown, while tetragonal phase crystals exhibit d33 up to 2000 pC/N and S3 up to 0.45% strain. These crystals show the highest electrostrictive strains yet reported for an inorganic compound. The unusually high electrostriction is discussed in relation to an energy landscape that allows ferroelastic and ferroelectric distortions to be simultaneously accessible at the nanometer scale.

Sheets, Sossity A.; Soukhojak, Andrey N.; Ohashi, Naoki; Chiang, Yet-Ming

2001-11-01

277

Ferroelectric Liquid Crystals  

Microsoft Academic Search

The main advances in the field of bulk ferroelectric liquid crystals since 1984 are reviewed. Recent experiments have shown that the molecular tilt and the in-plane spontaneous polarization are not strictly proportional to each other as assumed before. Microscopic experiments such as NMR and NQR have further allowed for a determination of the basic order parameters as a function of

Robert Blinc; Cene Filipi?; Adrijan Levstik; BošTjan Žekš; T. Carlsson

1987-01-01

278

Polaronic Effects in Ferroelectrics  

Microsoft Academic Search

We studied polaronic effects due to the interaction of an electron with optical phonons in ferroelectric materials with a layered crystal structure. We evaluated the polaron self-energy part using the effective T-matrix approach. It has been shown that transition from the large radius polaron to the small radius polaron is controlled by the interlayer interaction or interlayer spacing. We have

Y. M. Malozovsky; J. D. Fan; D. Bagayoko; J. T. Wang

2000-01-01

279

Scaling Effects on Ferro-Electrics: Application in Nanoelectronics and Characterization  

NASA Astrophysics Data System (ADS)

Ferroelectric thin films have been attractive for multifunctional devices like nonvolatile memory (FeRAM) using hysteresis behavior, DRAM using high permittivity, micro-actuator using piezoelectricity, infrared sensor using pyroelectricity, optical switch shutter display, etc. Thin-film nanoscale device structures integrated onto Si chips have made inroads into the semiconductor industry. These applications need not only ferroelectric high quality materials but also ability to keep the ferroelectricity at low dimension after fabrication of nano-scale objects. For these reasons, advanced characterization techniques for probing the properties of ferroelectric materials at nano-scale dimensions are now required. Among them, techniques based on the Atomic Force Microscope (AFM) have proved their efficiency for mapping the ferroelectric behavior of thin films with a nanometric resolution.

Vilquin, B.; Gautier, B.; Brugère, A.; Moulet, J. S.

2009-09-01

280

Adjustable ferroelectric properties in paraelectric\\/ferroelectric\\/paraelectric trilayers  

Microsoft Academic Search

A trilayer paraelectric\\/ferroelectric\\/paraelectric system is studied within the framework of the Ginzburg-Landau-Devonshire theory in consideration of the elastic interactions between each layer. An analytic expression of the ferroelectric phase transition temperature for the ferroelectric layer is derived. The polarization, dielectric properties and the response to the external field are studied numerically. Our results show that there are two types of

Xiao Yan Lu; Biao Wang; Yue Zheng; Chen Liang Li

2008-01-01

281

Adjustable ferroelectric properties in paraelectric\\/ferroelectric\\/paraelectric trilayers  

Microsoft Academic Search

A trilayer paraelectric\\/ferroelectric\\/paraelectric system is studied within the framework of the Ginzburg–Landau–Devonshire theory in consideration of the elastic interactions between each layer. An analytic expression of the ferroelectric phase transition temperature for the ferroelectric layer is derived. The polarization, dielectric properties and the response to the external field are studied numerically. Our results show that there are two types of

XiaoYan Lu; Biao Wang; Yue Zheng; ChenLiang Li

2008-01-01

282

Domain switching of fatigued ferroelectric thin films  

SciTech Connect

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

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

2014-05-12

283

Effects of doping on ferroelectric properties and leakage current behavior of KNN-LT-LS thin films on SrTiO3 substrate  

NASA Astrophysics Data System (ADS)

We report the effects of Ba, Ti, and Mn dopants on ferroelectric polarization and leakage current of (K0.44Na0.52Li0.04)(Nb0.84Ta0.1Sb0.06)O3 (KNN-LT-LS) thin films deposited by pulsed laser deposition. It is shown that donor dopants such as Ba2+, which increased the resistivity in bulk KNN-LT-LS, had an opposite effect in the thin film. Ti4+ as an acceptor B-site dopant reduces the leakage current by an order of magnitude, while the polarization values showed a slight degradation. Mn4+, however, was found to effectively suppress the leakage current by over two orders of magnitude while enhancing the polarization, with 15 and 23 ?C/cm2 remanent and saturated polarization, whose values are ˜70% and 82% of the reported values for bulk composition. This phenomenon has been associated with the dual effect of Mn4+ in KNN-LT-LS thin film, by substituting both A- and B-site cations. A detailed description on how each dopant affects the concentrations of vacancies in the lattice is presented. Mn-doped KNN-LT-LS thin films are shown to be a promising candidate for lead-free thin films and applications.

Abazari, M.; Safari, A.

2009-05-01

284

Molecular ferroelectrics: where electronics meet biology  

PubMed Central

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

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

2013-01-01

285

Characteristic temperatures of PbFe1/2Nb1/2O3 ferroelectrics crystals seen via acoustic emission  

NASA Astrophysics Data System (ADS)

PbFe1/2Nb1/2O3 ferroelectrics crystals have been investigated using an acoustic emission. All the characteristic points have been detected: the Néel antiferromagnetic-paramagnetic phase transition at 158.6 K, both the rhombohedral-tetragonal at 363-348 K and tetragonal-cubic at 382-365 K structural phase transitions, the intermediate temperature T* at 431-427.5 K and the Burns temperature T d, extending through 564-603 K. It is shown that a dielectric response is unable to locate the T d correctly, but both the thermal expansion and acoustic emission are able. Acoustic emission is found to be more powerful for T* than for T d, which is usually observed in some well known relaxor ferroelectrics. Such a phenomenon is discussed from a viewpoint of dynamics of polar nanoregions.

Dul'kin, E.; Kania, A.; Roth, M.

2014-03-01

286

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

287

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

288

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

SciTech Connect

We report the results of neutron elastic scattering measurements between -250oC and 620oC on the lead-free relaxor Na1/2Bi1/2TiO3 (NBT). Strong, anisotropic, elastic diffuse scattering intensity decorates the (100), (110), (111), (200), (220), and (210) Bragg peaks at room temperature. The wavevector dependence of this diffuse scattering is compared to that in the lead-based relaxor PbMg1/3Nb2/3O3 (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 = 523oC, 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 et al. (2003); these vanish below 320oC 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 [1 1 0] from 40 to 60 while doubling the associated integrated diffuse scattering. Similar behavior was reported by Matsuura et al. (2006) for 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 ( ) superlattice reflection associated with the Cc space group based on the atomic coordinates published in the x-ray study by Aksel et al. (2011) for NBT. We argue that a skin effect, analogous to that reported in the relaxors PZN and PMN-10%PT, can reconcile our single-crystal data with the powder data of Aksel et al. We believe this represents the first evidence of the relaxor skin effect in a lead-free relaxor.

Ge, Wenwei [Virginia Polytechnic Institute and State University] [Virginia Polytechnic Institute and State University; Devreugd, Christopher [Virginia Polytechnic Institute and State University] [Virginia Polytechnic Institute and State University; Phelan, Daniel [National Institute of Standards and Technology (NIST), Gaithersburg, MD] [National Institute of Standards and Technology (NIST), Gaithersburg, MD; Zhang, Qinjui [Shanghai Institute of Ceramics, Chinese Academy of Sciences (SICCAS)] [Shanghai Institute of Ceramics, Chinese Academy of Sciences (SICCAS); Muhtar, Aheart [Carnegie Institution of Washington] [Carnegie Institution of Washington; Li, Jiefang [Virginia Polytechnic Institute and State University] [Virginia Polytechnic Institute and State University; Luo, Haosu [Shanghai Institute of Ceramics, Chinese Academy of Sciences (SICCAS)] [Shanghai Institute of Ceramics, Chinese Academy of Sciences (SICCAS); Boatner, Lynn A [ORNL] [ORNL; Viehland, Dwight [Virginia Polytechnic Institute and State University] [Virginia Polytechnic Institute and State University; Gehring, P. M. [National Institute of Standards and Technology (NIST)] [National Institute of Standards and Technology (NIST)

2013-01-01

289

1. INTRODUCTION Ferroelectric (FE) capacitors have long been  

E-print Network

1. INTRODUCTION Ferroelectric (FE) capacitors have long been recognized as suitable storage characteristics of the FE capacitor. In fact, the best modeling techniques used presently in memory circuit proposed [4]. The complex behavior of an FE capacitor in response to arbitrary voltage patterns is perhaps

Sheikholeslami, Ali

290

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

291

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

292

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

293

Conduction at a Ferroelectric Interface  

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

294

Pressure-induced kinetics of ferroelectric phase transitions  

NASA Astrophysics Data System (ADS)

The hydrostatic-pressure-induced kinetics of paraelectric-ferroelectric phase transitions is considered on the basis of the time-dependent Ginzburg-Landau theory. The exact solution describing the interphase boundary at first-order ferroelectric phase transitions is used for analyzing the movement of the interphase boundary under the influence of hydrostatic pressure. Temperature and pressure dependences of the interphase boundary width and velocity are calculated by using the experimental data in BaTiO3. Power laws of the temperature and pressure behavior of the interface velocity v=v(||T-Tc||) and v=v(||p-?c||) are found. The pressure hysteresis is calculated.

Gordon, A.; Dorfman, S.

1994-11-01

295

Examining graphene field effect sensors for ferroelectric thin film studies.  

PubMed

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

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

2013-09-11

296

All-Union Conference on the Physics of Ferroelectric Materials, 11th, Chernovtsy, Ukrainian SSR, Feb. 1987, Proceedings  

NASA Astrophysics Data System (ADS)

The papers contained in this volume provide an overview of fundamental and applied research in the physics of ferroelectrics conducted in the USSR. Topics discussed include the critical behavior of ferroelectrics with point and extended defects, thermodynamics of dipole glasses, static and dynamic properties of ferroelectrics of the system Sn(Pb)2P2S(Se)6, and induced photovoltaic effect in centrosymmetric ruby crystals. Papers are also presented on the characteristics of dielectric and optical anomalies associated with ferroelectric and ferroelastic transitions in LiNH4SO4, propagation of surface acoustic waves in piezoceramics in the presence of an electric field, and polymer and composite piezoelectrics.

Shuvalov, L. A.

1987-12-01

297

Journal of the Mechanics and Physics of Solids 56 (2008) 21172135 A study of electromechanical switching in ferroelectric  

E-print Network

switching in ferroelectric single crystals J.H. Yena , Y.C. Shua,Ã?, J. Shiehb , J.H. Yehb a Institute and experimental studies developed to investigate the switching behavior of ferroelectric single crystals experiments. It is found that depolarization has a non-trivial influence on attainable actuation strains. r

Shu, Yi-Chung

298

Proper, improper and hybrid improper ferroelectricity in oxide perovkites and related compounds  

NASA Astrophysics Data System (ADS)

Ferroelectricity in oxide perovskites and related compounds has been a topic of intensive research for more than 60 years. Recently, the coupling of the ferroelectric mode with other structural distortions has attracted an increasing interest since it offers promising and still widely unexplored possibilities to couple ferroelectricity with other functional properties and even to produce unusual phenomena. In this context, the trilinear coupling between ferroelectric and oxygen rotational modes in naturally occuring and artificial layered perovskites appeared as a practical way to produce unusual dielectric properties or achieve enhanced magneto-electric coupling. Here, I will first briefly reintroduce the concepts of proper, improper and hybrid improper ferroelectricity, highlighting how to rationalize better the concept of improper ferroelectricity. I will contrast the intrinsic behavior of these three classes of compounds in ferroelectric capacitors. Taking then the prototypical example of BiFeO3/LaFeO3 superlattices, I will illustrate how hybrid improper ferroelectricity and trilinear mode coupling is a promising route to potentially achieve electric switching of the magnetization. Finally, considering the case of PbTiO3/SrTiO3 superlattices, I will discuss how to access from first-principles the phase-transition sequence and finite temperature properties of complex systems combining various structural instabilities, which still remains a challenging issue.

Ghosez, Philippe

2013-03-01

299

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

300

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

301

Conductivity and interfacial charge induced phenomena in ferroelectric films and composites  

NASA Astrophysics Data System (ADS)

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

Wong, Chung Kwan

2005-11-01

302

Ferroelectric Based Technologies for Accelerators  

SciTech Connect

Ferroelectrics have unique intrinsic properties that make them extremely attractive for high-energy accelerator applications. Low loss ferroelectric materials can be used as key elements in RF tuning and phase shifting components to provide fast, electronic control. These devices are under development for different accelerator applications for the X, Ka and L-frequency bands. The exact design of these devices depends on the electrical parameters of the particular ferroelectric material to be used--its dielectric constant, loss tangent and tunability. BST based ferroelectric-oxide compounds have been found to be suitable materials for a fast electrically-controlled tuners. We present recent results on the development of BST based ferroelectric compositions synthesized for use in high power technology components. The BST(M) ferroelectrics have been tested using both transverse and parallel dc bias fields to control the permittivity. Fast switching of a newly developed material has been shown and the feasibility of using of ferroelectric-based accelerator components in vacuum and in air has been demonstrated.

Kanareykin, A.; Jing, C. [Euclid Techlabs LLC, Rockville, MD 20850 (United States); Nenasheva, E. [Ceramics Co. Ltd, St. Petersburg 194223 (Russian Federation); Kazakov, S. [KEK Tsukuba, 305-0801 Japan/Omega-P Inc., New Haven, CT 06511 (United States); Kozyrev, A. [St. Petersburg Electrical Engineering University, St. Petersburg 197376 (Russian Federation); Tagantsev, A. [EPFL, 1015 Lausanne (Switzerland); Yakovlev, V. [Fermi National Accelerator Laboratory, Batavia, IL 60510 (United States)

2009-01-22

303

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

NASA Astrophysics Data System (ADS)

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

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

2012-11-01

304

Ferroelectric domain structure of anisotropically strained NaNbO{sub 3} epitaxial thin films  

SciTech Connect

NaNbO{sub 3} 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 NaNbO{sub 3} films with varying film thickness on NdGaO{sub 3} 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 DyScO{sub 3}, TbScO{sub 3}, and GdScO{sub 3} single crystalline substrates, NaNbO{sub 3} films behave rather like a normal ferroelectric. The application of these rare-earth scandate substrates yields well-ordered ferroelectric stripe domains of the type a{sub 1}/a{sub 2} 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., E-mail: jutta.schwarzkopf@ikz-berlin.de; Braun, D.; Schmidbauer, M.; Duk, A. [Leibniz-Institute for Crystal Growth, Max-Born-Str. 2, 12489 Berlin (Germany); Wördenweber, R. [Forschungszentrum Jülich, Peter Grünberg Institute, Jülich (Germany)

2014-05-28

305

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

306

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

307

Determination of the quasistatic linear and non-linear dielectric response in relaxor materials  

Microsoft Academic Search

Temperature dependence of the first ?1 and third harmonic dielectric response ?3 in relaxor systems was studied both as a function of the dc electric field by utilising the charge accumulation technique and as a function of the ac electric field. Additional non-linear contribution was found in the ac field dependence of ?1 in lead magnesium niobate single crystals and

Zdravko Kutnjak; Cene Filipi?; Adrijan Levstik

2002-01-01

308

Vibrational, magnetic, and dielectric behavior of La-substituted BiFeO3-PbTiO3  

NASA Astrophysics Data System (ADS)

Phonons and magnetic and ferroelectric ordering in La-substituted (Bi1-xLax)0.5Pb0.5Fe0.5Ti0.5O3 for samples with 0.0 ? x ? 0.5 are investigated using Raman, magnetization, and polarization measurements as a function of temperature. The system is tetragonal for pure Bi0.5Pb0.5Fe0.5Ti0.5O3 with a large c/a ratio. The anisotropy is reduced when Bi is partially replaced by La (0 ? x ? 0.5), and it turns cubic for x ? 0.4. All the properties are found to change significantly with changes in the c/a ratio. Evidence of spin-glass-like magnetic ordering at low temperature is found in the case of x = 0.2. A mechanism for the systematic change of magnetic ordering temperature as a function of doping is also discussed. The phonon frequencies and line widths exhibit discontinuous changes across the tetragonal-cubic transition. Large polarization and forbidden Raman scattering in the cubic phase are explained on the basis of symmetry breaking due to the formation of a polar nano region, which leads to relaxor behavior.

Mishra, K. K.; Satya, A. T.; Bharathi, A.; Sivasubramanian, V.; Murthy, V. R. K.; Arora, A. K.

2011-12-01

309

Ferroelectric capacitor with reduced imprint  

DOEpatents

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

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

1997-01-01

310

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

311

High-pressure studies of ferroelectric phases related to the earth and planetary interiors  

Microsoft Academic Search

Dielectric property measurements to 5.5 GPa have been conducted on single crystals and polycrystalline aggregates of several ferroelectrics (BaTiO3, Pb(Zr, Ti)O3, triglycine sulfate, Rochelle salt) for the purpose of determining the effects of high-pressure constraints on the overall behavior of ferroelectrics (FE) of both the perovskite 'soft-mode' and hydrogen-bonded types. It is found that dielectric hysteresis is possible in FE

G. W. Timco; H. H. Schloessin

1978-01-01

312

Programmable ferroelectric tunnel memristor  

NASA Astrophysics Data System (ADS)

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

Quindeau, Andy; Hesse, Dietrich; Alexe, Marin

2014-02-01

313

Electrostrictive Properties of Pb(Mg1/3Nb2/3)O3-Based Relaxor Ferroelectric Ceramics  

NASA Astrophysics Data System (ADS)

Perovskite-type Pb(Mg1/3Nb2/3)O3 (PMN)-based ceramics were prepared by modifying La(Mg2/3Nb1/3)O3 and PbTiO3. Dielectric and electrostrictive properties of modified PMN-based ceramics were investigated from the viewpoint of actuator materials. The temperature dependence of the dielectric constant, \\varepsilons, shows a broader peak compared with that of pure PMN in the vicinity of room temperature. Transverse electrostrictive strain, S{=}-3.0× 10-4, was induced under an applied electric field of 10 kV/cm.

Takagi, Harumi; Sakata, Koichiro; Takenaka, Tadashi

1993-09-01

314

Nanoscale phenomena in ferroelectric thin films  

Microsoft Academic Search

Ferroelectric materials are a subject of intense research as potential candidates for applications in non-volatile ferroelectric random access memories (FeRAM), piezoelectric actuators, infrared detectors, optical switches and as high dielectric constant materials for dynamic random access memories (DRAMs). With current trends in miniaturization, it becomes important that the fundamental aspects of scaling of ferroelectric and piezoelectric properties in these devices

Chandan S. Ganpule

2001-01-01

315

A ferromagnetic ferroelectric cofired ceramic for hyperfrequency  

NASA Astrophysics Data System (ADS)

A series of composite materials were prepared by cofired ceramics technology with 0.8Pb(Ni1/3Nb2/3)O3-0.2PbTiO3 (PNNT) and Ba2Zn1.2Cu0.8Fe12O22 as two components. The weight fraction of PNNT, signed as x, varied from 0.1 to 0.9. The coexistence of two phases in the composites was observed directly via scanning electron microscopy, and proved by x-ray diffraction spectra. The composites show excellent cofiring behavior. According to ferromagnetic and ferroelectric hysteresis loops, the composites exhibit both ferromagnetic and ferroelectric properties over a wide composition range (x=0.1-0.9). The composites have excellent magnetic and dielectric properties in hyperfrequency. With the rise of x, permeability decreases and permittivity increases. The permittivity resonant peak shifts to higher frequency with the decrease of x. Maxwell-Garnett equations are used to fit the permeability and permittivity of the composites. It can give valuable predication for composite material design. These composites are promising for applying in truly integrated passive filter in hyperfrequency.

Bai, Yang; Zhou, Ji; Gui, Zhilun; Li, Longtu; Qiao, Lijie

2007-04-01

316

Analysis of relaxor mechanism and structural distortion for SrBi1.6Nd0.4Nb2O9 bismuth-layer-structured ceramics  

NASA Astrophysics Data System (ADS)

The 1/2{h00} and 1/2{hk0} type superlattice reflections in the electron diffraction patterns indicate the presence of ordered polar regions in SrBi1.6Nd0.4Nb2O9. The research of x-ray Rietveld refinement and synchrotron radiation x-ray absorption fine structure spectroscopy determined that Nd3+ replaced Bi3+ in the Bi2O2 layers for SrBi1.6Nd0.4Nb2O9 and the relaxor behavior could be attributed to the disorder of Nd3+ and Bi3+ in the Bi2O2 layers. The tilting angle of NbO6 is obtained by Rietveld refinement method and the refinement result indicates that the substitution of Nd3+ for Bi3+ remarkably decrease the structural distortion, which leads to the lower transition temperature.

Sun, Lin; Chu, Junhao; Feng, Chude; Chen, Lidong

2007-12-01

317

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

318

Tunable DBR resonators using KTN ferroelectric thin-films  

Microsoft Academic Search

Tunable dual behavior resonators were realized on using KTN ferroelectric thin-films. Their measurements demonstrated an agility of more than 21% in the 6.2-7.6 GHz frequency range under an applied field of 80 kV\\/cm. At the same time, insertion losses at the center frequency decreased from 3.27 to 2.06 dB; reflection losses were better than 11.5 dB at the same frequency.

Vincent Laur; A. Moussavou; G. Tanne; P. Laurent; V. Bouquet; S. Deputier; M. Guilloux-Viry; F. Huret

2007-01-01

319

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. PMID:22655750

2012-01-01

320

Polarization relaxation kinetics in ultrathin ferroelectric capacitors A. Stamm, D. J. Kim, H. Lu, C. W. Bark, C. B. Eom et al.  

E-print Network

Polarization relaxation kinetics in ultrathin ferroelectric capacitors A. Stamm, D. J. Kim, H. Lu density nanocomposite capacitors using non-ferroelectric nanowires Appl. Phys. Lett. 102, 063901 (2013) Insulation degradation behavior of multilayer ceramic capacitors clarified by Kelvin probe force microscopy

Eom, Chang Beom

321

Recent patents on perovskite ferroelectric nanostructures.  

PubMed

Ferroelectric oxide materials with a perovskite structure have promising applications in electronic devices such as random access memories, sensors, actuators, infrared detectors, and so on. Recent advances in science and technology of ferroelectrics have resulted in the feature sizes of ferroelectric-based electronic devices entering into nanoscale dimensions. At nanoscale perovskite ferroelectric materials exhibit a pronounced size effect manifesting itself in a significant deviation of the properties of low-dimensional structures from the bulk and film counterparts. One-dimensional perovskite ferroelectric nanotube/nanowire systems, offer fundamental scientific opportunities for investigating the intrinsic size effects in ferroelectrics. In the past several years, much progress has been made both in fabrication and physical property testing of perovskite ferroelectric nanostructures. In the first part of this paper, the recent patents and literatures for fabricating ferroelectric nanowires, nanorods, nanotubes, and nanorings with promising features, are reviewed. The second part deals with the recent advances on the physical property testing of perovskite ferroelectric nanostructures. The third part summarizes the recently patents and literatures about the microstructural characterizations of perovskite ferroelectric nanostructures, to improve their crystalline quality, morphology and uniformity. Finally, we conclude this review with personal perspectives towards the potential future developments of perovskite ferroelectric nanostructures. PMID:19149754

Zhu, Xinhua

2009-01-01

322

Ferroelectric Fluid Flow Control Valve  

NASA Technical Reports Server (NTRS)

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

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

1999-01-01

323

Effects of Ca-substitution on structural, dielectric, and ferroelectric properties of Ba5SmTi3Nb7O30 tungsten bronze ceramics  

NASA Astrophysics Data System (ADS)

Effects of Ca-substitution on the crystal structure and dielectric properties were investigated for Ba5SmTi3Nb7O30 tungsten bronze ceramics. The tetragonal tungsten bronze structure in space group P4bm was determined in Ba4CaSmTi3Nb7O30 ceramics, which was the same for Ba5SmTi3Nb7O30. The c-axis off center displacement in both B1 and B2-sites for Ba5SmTi3Nb7O30 was slightly larger than that in BaCaSmTi3Nb7O30, while the distortion of Ti/Nb(2)O6 octahedra in Ba4CaSmTi3Nb7O30 was obviously suppressed compared with that in Ba5SmTi3Nb7O30. Though there were also two dielectric anomalies observed in Ba4CaSmTi3Nb7O30, the relaxor ferroelectric nature was changed to the normal ferroelectric one, and both the endothermal peak in differential scanning calorimetry curve and the significant thermal hysteresis of the phase transition confirmed the first order ferroelectric transition. These results indicated that the ferroelectric nature of Ba4CaSmTi3Nb7O30 was more close to that in Ba4Sm2Ti4Nb6O30, and it could be concluded that the ferroelectric nature in filled tungsten bronze ceramics was primarily dominated by the A-site occupation rather than B-site occupation.

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

2012-07-01

324

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

325

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

326

Flexible relaxor materials: Ba2PrxNd1-xFeNb4O15 Tetragonal Tungsten Bronze solid solution  

E-print Network

@icmcb-bordeaux.cnrs.fr Abstract Relaxors are very interesting materials but they are most of the time restricted to perovskite free materials. In the case of close packed perovskite structure such a coexistence has already beenFlexible relaxor materials: Ba2PrxNd1-xFeNb4O15 Tetragonal Tungsten Bronze solid solution Elias

Boyer, Edmond

327

Magnetic control of ferroelectric polarization  

E-print Network

of Applied Physics, University of Tokyo, Tokyo 113-8656, Japan 2 Institute of Materials Science, University of candidate materials is limited and the effects are typically too small to be useful in applications. Here we report the discovery of ferroelectricity in a perovskite manganite, TbMnO3, where the effect of spin

Chandra, Premi

328

Ferroelectric perovskites for electromechanical actuation  

Microsoft Academic Search

There has been a recent surge of activity in ferroelectric materials motivated by the desire for materials capable of large strains for actuator applications. New materials have been developed and systematic attempts to exploit underlying domains have been pursued. New experimental methods have probed the material at the atomistic and domain scales. Significant advances have been made in the theoretical

K Bhattacharya; G Ravichandran

2003-01-01

329

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

SciTech Connect

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

2014-03-31

330

Finite-Temperature Investigation of Ferroelectric Solid Solutions from  

E-print Network

- cations. Examples include piezoelectric transducers, actuators, and non-volatile ferroelectric memoriesFinite-Temperature Investigation of Ferroelectric Solid Solutions from First discussed. INTRODUCTION Ferroelectric materials are of growing importance for a variety of device appli

Vanderbilt, David

331

Electromigration of microspheres in ferroelectric smectic liquid crystals  

NASA Astrophysics Data System (ADS)

When an electric field is applied to microspheres which are dispersed in a ferroelectric smectic liquid crystal, particle translation along the smectic layer plane, i.e., in a direction nearly perpendicular to that of the director, can be observed. Under certain electric field conditions the translation is shown to be linear in time. We have determined the stability regime of linear particle displacement in the parameter space of amplitude and frequency for various applied wave forms. This regime enlarges for increasing electric field amplitude and frequency, with a threshold behavior observed for small parameters. The upper stability boundary is related to the reciprocal ferroelectric switching time. The microspheres translational velocity is independent of the applied electric field amplitude, but increases linearly with applied frequency. The microsphere velocity also increases with increasing temperature, which is indicative of the respective decrease in liquid crystal viscosity. Possible mechanisms of electric-field-induced particle motion are discussed.

Dierking, I.; Cass, P.; Syres, K.; Cresswell, R.; Morton, S.

2007-08-01

332

The influence of ferroelectric KTN particles on electric properties of 0 3 ferroelectric composites  

Microsoft Academic Search

A triphasic ferroelectric composite is obtained when ferroelectric potassium tantalate niobate particles [KTN] with a high dielectric constant and electric conductivity are embedded in a traditional 0-3 manganese and niobate modified lead zirconate titanate [PMNZT]\\/polyvinylidene fluoride trifluoroethylene [P(VDF-TrFE)] copolymer biphasic-ferroelectric composite. The electric properties are studied for the ferroelectric composite in which the volume fraction of KTN particles is in

Yang Feng-Xia; Zhang Duan-Ming; Deng Zhong-Wei; Cheng Zhi-Yuan; Jiang Sheng-Lin

2008-01-01

333

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

334

New Ferroelectrics for Naval SONAR and Modeling of Nanoscale Ferroelectric Nonvolatile Memory Materials  

E-print Network

New Ferroelectrics for Naval SONAR and Modeling of Nanoscale Ferroelectric Nonvolatile Memory Navigation and Ranging (SONAR). At the nanoscale, our quantum-mechanical studies show that ferroelectricity with high piezoelectric response are of particular interest as they may be employed as sensors in SONAR

Rappe, Andrew M.

335

Testing of new ferroelectric elements custom engineered for explosively driven ferroelectric applications  

Microsoft Academic Search

Explosively driven ferroelectric generators (FEGs) are reliable, compact, high voltage sources that utilize high pressures to liberate charge trapped in the crystal structure of ferroelectric materials. For the active ferroelectric element most FEG designs use commercial lead zirconate-titanate (PZT) compositions designed for either precision actuators or naval sonar transducers. However, the material properties that are important in FEG applications are

S. L. Holt; J. T. Krile; D. J. Hemmert; W. S. Hackenberger; E. F. Alberta; J. W. Walter; J. C. Dickens; L. L. Altgilbers; A. H. Stults

2007-01-01

336

Testing of New Ferroelectric Elements Custom Engineered for Explosively Driven Ferroelectric Generator Applications  

Microsoft Academic Search

Summary form only given. Explosively driven ferroelectric generators (FEGs) are reliable, compact, high voltage sources that utilize high pressures to liberate charge trapped in the crystal structure of ferroelectric materials. For the active ferroelectric element most FEG designs use commercial lead zirconate-titanate (PZT) compositions designed for either precision actuators or naval sonar transducers. However, the material properties that are important

S. L. Holt; J. T. Krile; D. J. Hemmert; W. S. Hackenberger; E. F. Alberta; J. W. Walter; J. C. Dickens; L. L. Altgilbers; A. H. Stults

2007-01-01

337

Investigation of ferroelectricity and piezoelectricity in ferroelectric thin film capacitors using synchrotron x-ray microdiffraction  

Microsoft Academic Search

Ferroelectric materials have a wide range of applications in nonvolatile memory devices, sensors, and actuators due to their properties such as remnant polarization and piezoelectricity. It is necessary to investigate those properties to understand physical phenomena in ferroelectric materials and to have better device performance. Since ferroelectricity and piezoelectricity are directly related to structure at the scale of a single

Dal-Hyun Do

2006-01-01

338

Large piezoelectric strains from polarization graded ferroelectrics  

Microsoft Academic Search

The potential applications of polarization graded ferroelectrics as high performance sensors and actuators are theoretically investigated. A static bending can be expected in polarization graded ferroelectric plates, forming a vertical displacement. This is due to the built-in strain gradient that arises from the grading of the composition and concomitantly, the spontaneous self-strain. Numerical results of two compositionally graded ferroelectrics, BaTiO3-Ba1-xSrxTiO3

S. Zhong; Z.-G. Ban; S. P. Alpay; J. V. Mantese

2006-01-01

339

Scaling effects of relaxor-PbTiO3 crystals and composites for high frequency ultrasound  

NASA Astrophysics Data System (ADS)

The dielectric and piezoelectric properties of Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) and Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 (PIN-PMN-PT) ferroelectric single crystals were investigated as a function of thickness/scale in monolithic and piezoelectric/polymer 1-3 composites. For the case of PMN-PT single crystals, the dielectric (?33T/?0) and electromechanical properties (k33) were found to significantly decrease with decreasing thickness (500-40 ?m), while minimal thickness dependency was observed for PIN-PMN-PT single crystals. Temperature dependent dielectric behavior of the crystals suggested that the observed thickness dependence in PMN-PT was strongly related to their relatively large domain size (>10-20 ?m). As anticipated, 1-3 composite comprised of PIN-PMN-PT crystals exhibited superior properties to that of PMN-PT composite at high frequencies (>20 MHz). However, the observed couplings, being on the order of 80%, were disappointedly low when compared to their monolithic counterparts, the result of surface damage introduced during the dicing process, as evidenced by the broadened [002] peaks in the x-ray diffraction pattern.

Lee, Hyeong Jae; Zhang, Shujun; Shrout, Thomas R.

2010-06-01

340

Switchable diode effect in ferroelectric thin film: High dependence on poling process and temperature  

NASA Astrophysics Data System (ADS)

Pb(Zr0.53Ti0.47)O3 (PZT) thin film was fabricated on Pt/Ti/SiO2/Si substrate by chemical solution deposition method. Our results show a very great switchable ferroelectric diode effect (SFDE) in Pt-PZT-Au structure, which is more obvious and controllable than that in other ferroelectric thin films. The electrical conduction exhibits high rectifying behavior after pre-poling and the polarity of ferroelectric diode can be switched by changing the orientation of polarization in ferroelectric thin film. Our results also indicate that the SFDE in PZT film is highly dependent on remanent polarization and temperature. With the increase of remanent polarization, the forward current of bistable rectifying behavior observably reduces. Therefore, our measurement indicated that the biggest rectification ratio can reach about 220, which is found in 250K after +10V poling. By analyzing the conduction data, it is found that the dominant conduction mechanism of the SFDE in this sample is due to the space-charge-limited bulk conduction (SCLC), and Schottky emission (SE) may play subordinate role in forward bias voltage. Our observation demonstrates that SFDE may be general characteristic in ferroelectrics as long as proper electrodes chosen.

Li, Z. X.; Liu, X. L.; Chen, W. J.; Zhang, X. Y.; Wang, Ying; Xiong, W. M.; Zheng, Yue

2014-12-01

341

Ferroelectric studies of excessive Sm{sup 3+} containing perovskite PZT and pyrochlore biphase ceramics  

SciTech Connect

Polycrystalline samples of Sm{sup 3+} modified Pb{sub 1?x} Sm{sub 2x/3} (Zr{sub 0.6}Ti{sub 0.4}) O{sub 3} (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 Sm{sub 2}Ti{sub 2}O{sub 7} 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; Sastry, D. L., E-mail: dl-sastry@yahoo.com [Physics Department, Andhra University, Visakhapatnam - 530 003, AP (India); Ramesh, K. V. [Department of Engineering Physics, GITAM University, Visakhapatnam - 530 045, AP (India); Reddy, V. Raghavendra [UGC-DAE Consortium for Scientific Research, University Campus, Indore-452017, MP (India)

2014-04-24

342

Artificial ferroelectricity in perovskite superlattices  

NASA Astrophysics Data System (ADS)

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

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

2004-11-01

343

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

344

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

345

Magnetic control of ferroelectric polarization.  

PubMed

The magnetoelectric effect--the induction of magnetization by means of an electric field and induction of polarization by means of a magnetic field--was first presumed to exist by Pierre Curie, and subsequently attracted a great deal of interest in the 1960s and 1970s (refs 2-4). More recently, related studies on magnetic ferroelectrics have signalled a revival of interest in this phenomenon. From a technological point of view, the mutual control of electric and magnetic properties is an attractive possibility, but the number of candidate materials is limited and the effects are typically too small to be useful in applications. Here we report the discovery of ferroelectricity in a perovskite manganite, TbMnO3, where the effect of spin frustration causes sinusoidal antiferromagnetic ordering. The modulated magnetic structure is accompanied by a magnetoelastically induced lattice modulation, and with the emergence of a spontaneous polarization. In the magnetic ferroelectric TbMnO3, we found gigantic magnetoelectric and magnetocapacitance effects, which can be attributed to switching of the electric polarization induced by magnetic fields. Frustrated spin systems therefore provide a new area to search for magnetoelectric media. PMID:14603314

Kimura, T; Goto, T; Shintani, H; Ishizaka, K; Arima, T; Tokura, Y

2003-11-01

346

First principles study on the ferroelectricity of the perovskite ABO3 ferroelectrics  

NASA Astrophysics Data System (ADS)

In order to understand well the different ferroelectric behaviour of quantum paraelectrics and ferroelectrics and the origin of the ferroelectricity of the solid solution KTa0.5Nb0.5O3(KTN), we calculated the electronic structure of CaTiO3, BaTiO3 and KTN by first principles calculation. From total energy analysis, it is shown that, with increasing cell volume, the crystals (CaTiO3, SrTiO3) will have a ferroelectric instability. For BaTiO3, the ferroelectricity will disappear as the cell volume is decreased. From the density of states analysis, it is shown that the hybridization between B d and O p is very important for the ferroelectric stability of ABO3 perovskite ferroelectrics. This is consistent with the analysis of band structure.

Wang, Yuan-Xu; Zhong, Wei-Lie; Wang, Chun-Lei; Zhang, Pei-Lin; Su, Xuan-Tao

2002-07-01

347

High Temperature Ferroelectrics for Actuators: Recent Developments and Challenges  

NASA Technical Reports Server (NTRS)

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

Sehirlioglu, Alp; Kowalski, Benjamin

2014-01-01

348

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

349

Relaxor-like dielectric response of spin liquid CuCrO{sub 2}  

SciTech Connect

Broadband dielectric analysis (10{sup ?2}-10{sup 7} Hz) of layered triangular lattice CuCrO{sub 2} 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., E-mail: nileshmazumder@gmail.com; Roy, R. [Physics Department, Jadavpur University, Kolkata-700032 (India); Ghorai, U. K.; Saha, S. [School of Materials Science and Nanotechnology, Jadavpur University, Kolkata-700032 (India); Chattopadhyay, K. K., E-mail: kalyan-chattopadhyay@yahoo.com [Physics Department, Jadavpur University, Kolkata-700032, India and School of Materials Science and Nanotechnology, Jadavpur University, Kolkata-700032 (India)

2014-04-24

350

Ferroelectric properties of triglycine sulfate crystals with a nonuniform distribution of chromium impurities  

Microsoft Academic Search

The specific features of the ferroelectric behavior of triglycine sulfate crystals with a nonuniform distribution of chromium impurities are analyzed. It is demonstrated that the dielectric hysteresis loops of the samples exhibit large shifts both along the polarization and electric field directions. The results obtained are well explained within the phenomenological approach with due regard for the gradient term in

V. N. Shut; I. F. Kashevich; S. R. Syrtsov

2008-01-01

351

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

352

Ogranic-Assisted Solid-State Reaction Method for Fabrication of PNN-PT Ceramics with Superior Ferroelectric Properties  

NASA Astrophysics Data System (ADS)

Relaxor ferroelectric ceramic materials have attracted considerable attentions due to their high dielectric constants and superior piezoelectric properties. Since such properties are associated with single perovskite phase, the synthesis process is of utmost importance. The traditional solid-state reaction encounters difficulties in eliminating pyrochlore phases. To synthesize pyrochlore-free Pb-based relaxors, other methods have been proposed including the columbite route, the chemical method and the mechanochemical reaction approach. However, they involve complicated processing procedures, high fabrication cost and inevitable contamination. To tackle these problems, this study aims to develop a simple and economical method for synthesis of Pb-based relaxors that can attain single perovskite phase, excellent electrical properties and high electric fatigue resistance while accommodating the demand of mass production. The key idea is to introduce organic materials into the ball-milling process of the conventional solid-state reaction so that the oxygen in the organics could assist the formation of the perovskite phase. In this work, 0.64Pb(Ni1/3Nb2/3)O 3-0.36PbTiO3 powders and ceramics with single perovskite structure have been successfully fabricated using a polyethylene glycol(PEG)-assisted method. The details of studies on the improvements of material properties like phase structure, microstructure, electrical properties and electric fatigue resistance have been presented. The major contributions can be highlighted in three aspects: (1) the successful demonstration of organic-assisted solid-state reaction method by synthesizing pyrochlore-free Ni1/3Nb2/3)O3-0.36PbTiO 3 powders via a PEG-assisted method, which yields drastically improved properties of ceramics in density, dielectrics and piezoelectrics as compared to those derived without PEG; (2) the study of chemical functional groups by comparing the assisting effects of polyalcohol and polyether, which finds that the hydroxyl oxygen is more effective in assisting the formation of the perovskite phase than the ether oxygen; and (3) the characterization of the Ni1/3Nb2/3)O3-0.36PbTiO3 ceramics fabricated by the organic-assisted method, which show superior performance as compared to those fabricated without the organic, particularly for electrical properties and electric fatigue characteristics. In summary, the organic-assisted method has shown its great potential in fabricating single-phase perovskite i1/3Nb2/3)O 3-PbTiO3 ceramics with superior electrical performance, high electric fatigue resistance and mass productability, making it suitable for wide industrial applications such as capacitors, actuators and transducers, etc.

Ye, Yin

353

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

354

Block copolymer/ferroelectric nanoparticle nanocomposites  

E-print Network

Block copolymer/ferroelectric nanoparticle nanocomposites Xinchang Pang,a Yanjie He,a Beibei Jiang and Zhiqun Lin*a Nanocomposites composed of diblock copolymer/ferroelectric nanoparticles were formed of PS-functionalized BaTiO3 NPs in the PS-b-PMMA/BaTiO3 NP nanocomposites. Selective solvent vapor

Lin, Zhiqun

355

A phenomenological cohesive model of ferroelectric fatigue  

E-print Network

A phenomenological cohesive model of ferroelectric fatigue I. Arias b S. Serebrinsky a, M. Ortiz Abstract We develop a phenomenological model of electro-mechanical ferroelectric fatigue based to fatigue are localized in one or more planar-like regions, modelled by the cohesive surfaces. We validate

Huerta, Antonio

356

Ferroelectric hysteresis (Polarization P vs. electric  

E-print Network

, USA Thin-film ferroelectric oxides for photovoltaic energy production The new ferroelectric oxide [KNb-Tower method. Characterization of the photovoltaic IV curve will be measured using a filtered Xenon arc lamp of physics, University of Central Florida, Orlando, FL 32816, USA 2SISOM thin films LLC., Orlando, FL 32805

Peale, Robert E.

357

Domain switching in polycrystalline ferroelectric ceramics  

E-print Network

ARTICLES Domain switching in polycrystalline ferroelectric ceramics J. Y. LI1, R. C. ROGAN2,3, E:10.1038/nmat1485 Ferroelectric ceramics are widely used as sensors and actuators for their electro collective process in commercially used polycrystalline ceramics that are agglomerations of a very large

Li, Jiangyu

358

Advanced piezoelectric–ferroelectric stack actuator  

Microsoft Academic Search

A conceptual design and an operational algorithm for an advanced piezoelectric–ferroelectric stack actuator are developed. The actuator takes advantage of the large strains due to the domain-switching phenomenon and utilizes the nonlinear range of response of the ferroelectric material. As a result, the proposed conceptual design allows for deformations that are considerably larger than the ones obtained using conventional piezoelectric

Uri Kushnir; Oded Rabinovitch

2009-01-01

359

Modeling and design of ferroelectric beam actuators  

Microsoft Academic Search

A non-linear bimorph device is proposed, in which the strain accompanying ferroelectric switching is used to drive curvature of a bilayer of ferroelectric material. An analysis of the proposed device suggests that a curvature about an order of magnitude greater than that readily obtained by conventional piezoelectric bimorphs is possible, whilst the peak tensile stresses in the device are comparable

John E. Huber

2004-01-01

360

Ferroelectric actuators in the electromechanical interface  

Microsoft Academic Search

The requirements of a control actuator are examined, and the unique capabilities of the type of an actuator driven by ferroelectric materials that exhibit piezoelectric characteristics when electrically poled to meet these requirements are demonstrated. It is shown that, when substantial energy is required from an actuator, actuators configured as stacks of ferroelectric disks are most suitable. They develop high

C. G. O'Neill; C. H. O'Neill

1990-01-01

361

Surface micromachined accelerometer using ferroelectric substrate  

Microsoft Academic Search

In this paper we describe a new accelerometer using ferroelectric material having a large dielectric constant, such as bulk PZT (?r=2600). The measuring principle is detection of the capacitance change caused by the dielectric mass movement in the fringe electrical field. Considering practical fabrication, ferroelectric material is used for the substrate instead of the suspended proof mass. Since capacitance is

Seiji Aoyagi; Sho Kumagai; Daiichiro Yoshikawa; Yuichi Isono

2007-01-01

362

Ferroelectric translational antiphase boundaries in nonpolar materials  

PubMed Central

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

363

Ferroelectric Liquid Crystal Conglomerates DAVID M. WALBA  

E-print Network

Chapter 8 Ferroelectric Liquid Crystal Conglomerates DAVID M. WALBA University of Colorado, Boulder 5.1 Crystal Conglomerates 5.2 Spontaneous Reflection Symmetry Breaking in Liquid Crystals 6 Chiral-471-05497-6 Copyright 2003 John Wiley & Sons, Inc. 457 #12;458 FERROELECTRIC LIQUID CRYSTAL CONGLOMERATES ferro-, pyro

Walba, David

364

Microscopic mechanisms for improper ferroelectricity in multiferroic perovskites: a theoretical review  

NASA Astrophysics Data System (ADS)

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 µC 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, Silvia; Yamauchi, Kunihiko; Sergienko, Ivan A.; Sen, Cengiz; Sanyal, Biplab; Dagotto, Elbio

2008-10-01

365

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

366

Thermal conductivity of geometrically frustrated, ferroelectric YMnO3: extraordinary spin-phonon interactions.  

PubMed

The thermal conductivity of the magnetically frustrated, ferroelectric YMnO3 exhibits an isotropic suppression in the cooperative paramagnetic state, followed by a sudden increase upon magnetic ordering. This unprecedented behavior without an associated static structural distortion probably originates from the strong dynamic coupling between acoustic phonons and low-energy spin fluctuations in geometrically frustrated magnets. The replacement of magnetic Ho for Y at the ferroelectrically active site results in an even larger effect, suggestive of the strong influence of multiferroicity. PMID:15525119

Sharma, P A; Ahn, J S; Hur, N; Park, S; Kim, Sung Baek; Lee, Seongsu; Park, J-G; Guha, S; Cheong, S-W

2004-10-22

367

NEW LEAD-FREE PEROVSKITE RELAXOR CERAMICS DERIVED FROM BaTiO3 AND CONTAINING SCANDIUM  

E-print Network

NEW LEAD-FREE PEROVSKITE RELAXOR CERAMICS DERIVED FROM BaTiO3 AND CONTAINING SCANDIUM ANNIE SIMON-ray diffraction and dielectric characterizations. Dielectric measurements performed on ceramics with 0 x 0 therefore been performed in detail on ceramics with BaTiO3-derived compositions.2-23 Thanks to frequency

Boyer, Edmond

368

Improper ferroelectricity in perovskite oxide artificial superlattices.  

PubMed

Ferroelectric thin films and superlattices are currently the subject of intensive research because of the interest they raise for technological applications and also because their properties are of fundamental scientific importance. Ferroelectric superlattices allow the tuning of the ferroelectric properties while maintaining perfect crystal structure and a coherent strain, even throughout relatively thick samples. This tuning is achieved in practice by adjusting both the strain, to enhance the polarization, and the composition, to interpolate between the properties of the combined compounds. Here we show that superlattices with very short periods possess a new form of interface coupling, based on rotational distortions, which gives rise to 'improper' ferroelectricity. These observations suggest an approach, based on interface engineering, to produce artificial materials with unique properties. By considering ferroelectric/paraelectric PbTiO3/SrTiO3 multilayers, we first show from first principles that the ground-state of the system is not purely ferroelectric but also primarily involves antiferrodistortive rotations of the oxygen atoms in a way compatible with improper ferroelectricity. We then demonstrate experimentally that, in contrast to pure PbTiO3 and SrTiO3 compounds, the multilayer system indeed behaves like a prototypical improper ferroelectric and exhibits a very large dielectric constant of epsilon(r) approximately 600, which is also fairly temperature-independent. This behaviour, of practical interest for technological applications, is distinct from that of normal ferroelectrics, for which the dielectric constant is typically large but strongly evolves around the phase transition temperature and also differs from that of previously known improper ferroelectrics that exhibit a temperature-independent but small dielectric constant only. PMID:18401406

Bousquet, Eric; Dawber, Matthew; Stucki, Nicolas; Lichtensteiger, Céline; Hermet, Patrick; Gariglio, Stefano; Triscone, Jean-Marc; Ghosez, Philippe

2008-04-10

369

Thin Layer Composite Unimorph Ferroelectric Driver and Sensor  

NASA Technical Reports Server (NTRS)

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

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

1995-01-01

370

Thin Layer Composite Unimorph Ferroelectric Driver and Sensor  

NASA Technical Reports Server (NTRS)

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

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

1997-01-01

371

Thin layer composite unimorph ferroelectric driver and sensor  

NASA Technical Reports Server (NTRS)

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

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

2004-01-01

372

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

373

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

374

Gamma Ray Irradiation Effects on the Ferroelectric and Piezoelectric Properties of Barium Titanate Ceramics  

NASA Astrophysics Data System (ADS)

The effect of heavy dose gamma ray irradiation on the ferroelectric and piezoelectric properties of barium titanate (BaTiO3) ceramics has been investigated. It is found that on irradiation the ferroelectric property decreases and polarization behavior shows double loop hysteresis. The piezoelectric properties including piezoelectric charge constant ( d 33), electromechanical coupling coefficient ( K p), and electrostrictive strain also decreases. The most probable reason for decreased ferroelectric and piezoelectric properties may be the occurrence of random local strain upon irradiation. The phase transition temperature from ferroelectric to paraelectric decreases and degree of diffuseness increases on irradiation. The thermoluminescence (TL) glow curve showed a peak at 226 °C showing that irradiated BaTiO3 has TL properties. Presence of TL clearly indicates that gamma ray irradiation causes trapped holes and electrons and these trapped charges are released at temperature higher than 226 °C. The creation of trapped holes and electrons effected the microstrain of BaTiO3 ceramic leading to change in the ferroelectric and piezoelectric properties of BaTiO3 ceramic.

Medhi, Nirmali; Nath, A. K.

2013-09-01

375

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

376

The influence of ferroelectric KTN particles on electric properties of 0 3 ferroelectric composites  

NASA Astrophysics Data System (ADS)

A triphasic ferroelectric composite is obtained when ferroelectric potassium tantalate niobate particles [KTN] with a high dielectric constant and electric conductivity are embedded in a traditional 0-3 manganese and niobate modified lead zirconate titanate [PMNZT]/polyvinylidene fluoride trifluoroethylene [P(VDF-TrFE)] copolymer biphasic-ferroelectric composite. The electric properties are studied for the ferroelectric composite in which the volume fraction of KTN particles is in the range 0%-24% and KTN is a passive phase. The experimental data show that the volume fraction of KTN particles strongly influence the electric properties of ferroelectric composite, and that the triphasic composite doped with KTN has higher ferroelectric, piezoelectric and pyroelectric properties than the biphasic composite with the same PMNZT volume fraction.

Feng-Xia, Yang; Duan-Ming, Zhang; Zhong-Wei, Deng; Zhi-Yuan, Cheng; Sheng-Lin, Jiang

2008-03-01

377

Glassy to inhomogeneous-ferroelectric crossover in (Pb, La)(Zr, Ti)O3 ceramics  

Microsoft Academic Search

The temperature dependence of the dielectric nonlinearity a3=?3\\/V14 has been determined in 9\\/65\\/35 (Pb, La)(Zr, Ti)O3 ceramics. In zero electric field a deep in the temperature behavior of the static a3 has been observed indicating a crossover from paraelectric-like to glass-like behavior on cooling towards the freezing transition. By varying a bias electric field another glass-to-ferroelectric crossover has been observed

V. Bobnar; Z. Kutnjak; A. Levstik

2000-01-01

378

Voltage drop at interfaces in multilayer ferroelectrics  

NASA Astrophysics Data System (ADS)

Based upon a defined surface barrier in ferroelectric multilayers deposited on (100) p-type silicon, ?Va, which bears a portion of the external electrical voltage, a modified empirical power law I=A(?V)n is established for quantitatively describing detailed I-V dependence in ferroelectric multilayers. The voltage drop at the interface, Vi, which directly affects electrical characteristics of ferroelectric multiplayer system, is studied thoroughly. The voltage drop obtained from the modified empirical power law of the I-V dependence is consistent with that obtained from the C-V dependence model.

Li, Xingjiao; Wang, Ningzhang; Bao, Junbo; Chen, Tao; Xu, Jingping; Feng, Hanhua; Li, Shaoping

2003-03-01

379

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

380

Ultrafast Photovoltaic Response in Ferroelectric Nanolayers  

SciTech Connect

We show that light drives large-amplitude structural changes in thin films of the prototypical ferroelectric PbTiO3 via direct coupling to its intrinsic photovoltaic response. Using time-resolved x-ray scattering to visualize atomic displacements on femtosecond timescales, photoinduced changes in the unit-cell tetragonality are observed. These are driven by the motion of photogenerated free charges within the ferroelectric and can be simply explained by a model including both shift and screening currents, associated with the displacement of electrons first antiparallel to and then parallel to the ferroelectric polarization direction.

Daranciang, Dan

2012-02-15

381

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

382

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

383

Dielectric constant tunability at microwave frequencies and pyroelectric behavior of lead-free submicrometer-structured (Bi0.5Na0.5)1-xBaxTiO3 ferroelectric ceramics.  

PubMed

In this article, we show that the dielectric constant of lead-free ferroelectric ceramics based on the solid solution (1-x)(Bi(0.5)Na(0.5))TiO(3)-xBaTiO(3), with compositions at or near the morphotropic phase boundary (MPB), can be tuned by a local applied electric field. Two compositions have been studied, one at the MPB, with x = 0.06 (BNBT6), and another one nearer the BNT side of the phase diagram, with x = 0.04 (BNBT4). The tunability of the dielectric constant is measured at microwave frequencies between 100 MHz and 3 GHz by a nonresonant method and simultaneously applying a dc electric field. As expected, the tunability is higher for the composition at the MPB (BNBT6), reaching a maximum value of 60% for an electric field of 900 V/cm, compared with the composition below this boundary (BNBT4), which saturates at 40% for an electric field of 640 V/cm. The high tunability in both cases is attributed to the fine grain and high density of the samples, which have a submicrometer homogeneous grain structure with grain size of the order of a few hundred nanometers. Such properties make these ceramics attractive for microwave tunable devices. Finally, we have tested these ceramics for their application as infrared pyroelectric detectors and we have found that the pyroelectric figure of merit is comparable to traditional lead-containing pyroelectrics. PMID:25004530

Martínez, Félix L; Hinojosa, Juan; Doménech, Ginés; Fernández-Luque, Francisco J; Zapata, Juan; Ruiz, Ramon; Pardo, Lorena

2013-08-01

384

Tunable metallic conductance in ferroelectric nanodomains.  

PubMed

Metallic conductance in charged ferroelectric domain walls was predicted more than 40 years ago as the first example of an electronically active homointerface in a nonconductive material. Despite decades of research on oxide interfaces and ferroic systems, the metal-insulator transition induced solely by polarization charges without any additional chemical modification has consistently eluded the experimental realm. Here we show that a localized insulator-metal transition can be repeatedly induced within an insulating ferroelectric lead-zirconate titanate, merely by switching its polarization at the nanoscale. This surprising effect is traced to tilted boundaries of ferroelectric nanodomains, that act as localized homointerfaces within the perovskite lattice, with inherently tunable carrier density. Metallic conductance is unique to nanodomains, while the conductivity of extended domain walls and domain surfaces is thermally activated. Foreseeing future applications, we demonstrate that a continuum of nonvolatile metallic states across decades of conductance can be encoded in the size of ferroelectric nanodomains using electric field. PMID:22181709

Maksymovych, Peter; Morozovska, Anna N; Yu, Pu; Eliseev, Eugene A; Chu, Ying-Hao; Ramesh, Ramamoorthy; Baddorf, Arthur P; Kalinin, Sergei V

2012-01-11

385

Phenomenological theories of ferroelectric phase transitions  

E-print Network

Phenomenological theories of ferroelectric phase transitions W. Cao parameter in the free energy expansion, phenomenological theory can also describe inhomogeneous structures appear-Phenomenological parent and product phases. phenomenological theories in multidimensions for describ-Phenomenological

Cao, Wenwu

386

Negative capacitance in a ferroelectric capacitor  

NASA Astrophysics Data System (ADS)

The Boltzmann distribution of electrons poses a fundamental barrier to lowering energy dissipation in conventional electronics, often termed as Boltzmann Tyranny. Negative capacitance in ferroelectric materials, which stems from the stored energy of a phase transition, could provide a solution, but a direct measurement of negative capacitance has so far been elusive. Here, we report the observation of negative capacitance in a thin, epitaxial ferroelectric film. When a voltage pulse is applied, the voltage across the ferroelectric capacitor is found to be decreasing with time—in exactly the opposite direction to which voltage for a regular capacitor should change. Analysis of this ‘inductance’-like behaviour from a capacitor presents an unprecedented insight into the intrinsic energy profile of the ferroelectric material and could pave the way for completely new applications.

Khan, Asif Islam; Chatterjee, Korok; Wang, Brian; Drapcho, Steven; You, Long; Serrao, Claudy; Bakaul, Saidur Rahman; Ramesh, Ramamoorthy; Salahuddin, Sayeef

2015-02-01

387

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

388

Negative capacitance in a ferroelectric capacitor.  

PubMed

The Boltzmann distribution of electrons poses a fundamental barrier to lowering energy dissipation in conventional electronics, often termed as Boltzmann Tyranny. Negative capacitance in ferroelectric materials, which stems from the stored energy of a phase transition, could provide a solution, but a direct measurement of negative capacitance has so far been elusive. Here, we report the observation of negative capacitance in a thin, epitaxial ferroelectric film. When a voltage pulse is applied, the voltage across the ferroelectric capacitor is found to be decreasing with time-in exactly the opposite direction to which voltage for a regular capacitor should change. Analysis of this 'inductance'-like behaviour from a capacitor presents an unprecedented insight into the intrinsic energy profile of the ferroelectric material and could pave the way for completely new applications. PMID:25502099

Khan, Asif Islam; Chatterjee, Korok; Wang, Brian; Drapcho, Steven; You, Long; Serrao, Claudy; Bakaul, Saidur Rahman; Ramesh, Ramamoorthy; Salahuddin, Sayeef

2015-02-01

389

Ultrafast Photovoltaic Response in Ferroelectric Nanolayers  

E-print Network

We show that light drives large-amplitude structural changes in thin films of the prototypical ferroelectric PbTiO[subscript 3] via direct coupling to its intrinsic photovoltaic response. Using time-resolved x-ray scattering ...

Daranciang, Dan

390

Interface control of bulk ferroelectric polarization  

PubMed Central

The control of material interfaces at the atomic level has led to novel 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 employ 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 underlayers extends the generality of this phenomenon. PMID:22647612

Yu, P.; Luo, W.; Yi, D.; Zhang, J. X.; Rossell, M. D.; Yang, C.-H.; You, L.; Singh-Bhalla, G.; Yang, S. Y.; He, Q.; Ramasse, Q. M.; Erni, R.; Martin, L. W.; Chu, Y. H.; Pantelides, S. T.; Pennycook, S. J.; Ramesh, R.

2012-01-01

391

Behaviorism  

ERIC Educational Resources Information Center

Early forms of psychology assumed that mental life was the appropriate subject matter for psychology, and introspection was an appropriate method to engage that subject matter. In 1913, John B. Watson proposed an alternative: classical S-R behaviorism. According to Watson, behavior was a subject matter in its own right, to be studied by the…

Moore, J.

2011-01-01

392

Some nonlinear properties of ferroelectric smart materials  

NASA Astrophysics Data System (ADS)

Four types of nonlinear properties of ferroelectric smart materials have been considered: nonlinear dynamics of the paraelectric-ferroelectric interphase boundaries, nonlinear equilibrium excitations-domain walls, nonlinear response of the domain structure near the first-order phase transition-wetting of domain walls-and nonlinear effects caused by external high magnetic fields. The above mentioned nonlinearities have been studied in (Ba,Sr)TiO 3(BST) and Pb(Zr,Ti)O 3(PZT).

Dorfman, Simon; Fuks, David; Gordon, Alex; Kotomin, Eugene; Wyder, Peter

2001-09-01

393

Nature of ferroelectric–paraelectric transition  

Microsoft Academic Search

Ferroelectric (FE) materials directly convert electrical energy to mechanical energy and are critical to applications such as sensors, transducers, and actuators. The giant electromechanical response is the manifestation of the critical point between the first-order and second-order ferroelectric–paraelectric (FE–PE) transitions. For the simple classic FE lead titanate (PbTiO3), it is commonly accepted that there is a critical point in the

Z. K. Liu; Z. G. Mei; Y. Wang; S. L. Shang

2012-01-01

394

Ferroelectric-ferromagnetic multilayers: A magnetoelectric heterostructure with high output charge signal  

NASA Astrophysics Data System (ADS)

Multiferroic composites and heterostructures comprising ferroelectric and ferromagnetic materials exhibit room-temperature magnetoelectric (ME) effects greatly exceeding those of single-phase magnetoelectrics known to date. Since these effects are mediated by the interfacial coupling between ferroic constituents, the ME responses may be enhanced by increasing the density of interfaces and improving their quality. A promising material system providing these features is a ferroelectric-ferromagnetic multilayer with epitaxial interfaces. In this paper, we describe theoretically the strain-mediated direct ME effect exhibited by free-standing multilayers composed of single-crystalline ferroelectric nanolayers interleaved by conducting ferromagnetic slabs. Using a nonlinear thermodynamic approach allowing for specific mechanical boundary conditions of the problem, we first calculate the polarization states and dielectric properties of ferroelectric nanolayers in dependence on the lattice mismatch between ferroic constituents and their volume fractions. In these calculations, the ferromagnetic component is described by a model which combines linear elastic behavior with magnetic-field-dependent lattice parameters. Then the quasistatic ME polarization and voltage coefficients are evaluated using the theoretical strain sensitivity of ferroelectric polarization and measured effective piezomagnetic coefficients of ferromagnets. For Pb(Zr0.5Ti0.5)O3-FeGaB and BaTiO3-FeGaB multilayers, the ME coefficients are calculated numerically as a function of the FeGaB volume fraction and used to evaluate the output charge and voltage signals. It is shown that the multilayer geometry of a ferroelectric-ferromagnetic nanocomposite opens the way for a drastic enhancement of the output charge signal. This feature makes biferroic multilayers advantageous for the development of ultrasensitive magnetic-field sensors for technical and biomedical applications.

Prokhorenko, S.; Kohlstedt, H.; Pertsev, N. A.

2014-09-01

395

Ferroelectric Liquid Crystal Chemistry: Cyanohydrin Ether and Cyanoalkyl Ferroelectric Liquid Crystals; Synthesis and Liquid Crystal Properties  

Microsoft Academic Search

From simple symmetry arguments it can be predicted that tilted chiral smectic liquid crystals should exhibit ferroelectric polarization. While these predictions are found to hold true, the symmetry arguments do not lead insight into the molecular origins of this phenomena. Such insight is necessary to allow the directed design of new high-performance ferroelectric liquid crystal materials is to be achieved.

Kirk Frederick Eidman

1988-01-01

396

Ab initio design of charge-mismatched ferroelectric superlattices  

NASA Astrophysics Data System (ADS)

We present a systematic approach to modeling the electrical and structural properties of charge-mismatched superlattices from first principles. Our strategy is based on bulk calculations of the parent compounds, which we perform as a function of in-plane strain and out-of-plane electric displacement field. The resulting two-dimensional phase diagrams allow us to accurately predict, without performing further calculations, the behavior of a layered heterostructure where the aforementioned building blocks are electrostatically and elastically coupled, with an arbitrary choice of the interface charge (originated from the polar discontinuity) and volume ratio. By using the [PbTiO3]m/[BiFeO3]n system as test case, we demonstrate that interface polarity has a dramatic impact on the ferroelectric behavior of the superlattice, leading to the stabilization of otherwise inaccessible bulk phases.

Cazorla, Claudio; Stengel, Massimiliano

2014-07-01

397

Electronic structures and ferroelectric instabilities of cubic AVO(3) (A = Sr, Ba, and Pb) perovskites by first-principles calculations.  

PubMed

The electronic properties and ferroelectric transition behaviors of three AVO(3) (A = Sr, Ba, and Pb) compounds are investigated by first-principles density functional theory (FP-DFT) in combination with soft-mode theory. The band structures and projection density of states (PDOS) confirm that the bonding properties of SrVO(3) and BaVO(3) are rather similar to each other, but different to that of PbVO(3). The bonding differences determine the ferroelectric transition behaviors of these compounds. For SrVO(3) and BaVO(3), no ferroelectric instability is observed and they possess cubic structures. The covalent interactions of Pb-O pairs are very important for the ferroelectric instability of PbVO(3). In comparison to PbTiO(3), we found that the V-O interactions further enhance the ferroelectric instability of PbVO(3), and therefore PbVO(3) shows a much larger tetragonal distortion than PbTiO(3). PMID:21389488

Yan, Shu-yao; Xie, Ying; Liu, Tao; Yu, Hai-tao

2010-03-31

398

Ferroelectric order in individual nanometre-scale crystals  

NASA Astrophysics Data System (ADS)

Ferroelectricity in finite-dimensional systems continues to arouse interest, motivated by predictions of vortex polarization states and the utility of ferroelectric nanomaterials in memory devices, actuators and other applications. Critical to these areas of research are the nanoscale polarization structure and scaling limit of ferroelectric order, which are determined here in individual nanocrystals comprising a single ferroelectric domain. Maps of ferroelectric structural distortions obtained from aberration-corrected transmission electron microscopy, combined with holographic polarization imaging, indicate the persistence of a linearly ordered and monodomain polarization state at nanometre dimensions. Room-temperature polarization switching is demonstrated down to ~5?nm dimensions. Ferroelectric coherence is facilitated in part by control of particle morphology, which along with electrostatic boundary conditions is found to determine the spatial extent of cooperative ferroelectric distortions. This work points the way to multi-Tbit/in2 memories and provides a glimpse of the structural and electrical manifestations of ferroelectricity down to its ultimate limits.

Polking, Mark J.; Han, Myung-Geun; Yourdkhani, Amin; Petkov, Valeri; Kisielowski, Christian F.; Volkov, Vyacheslav V.; Zhu, Yimei; Caruntu, Gabriel; Paul Alivisatos, A.; Ramesh, Ramamoorthy

2012-08-01

399

High Speed FPGA Model Implementation for Ferroelectric and Ferromagnetic Transducers  

E-print Network

High Speed FPGA Model Implementation for Ferroelectric and Ferromagnetic Transducers Operating Department of Mathematics North Carolina State University, Raleigh, NC 27695 ABSTRACT Ferroelectric and ferromagnetic materials are employed as both actuators and sensors in a wide variety of applications including

400

Dielectric property of ferroelectric-insulator-semiconductor junction  

Microsoft Academic Search

The voltage dependence of the high-frequency capacitance of a metal-ferroelectric-insulator-semiconductor (MFIS) structure is analyzed by relating the potential profile to the dielectric hysteresis of the ferroelectric thin film. About one hundredth of the dielectric polarization of ferroelectric ceramic PZT is enough to control the Si surface potential for ferroelectric gate FET memory, and large coercive force is required to obtain

Masanori Okuyama; Wenbiao Wu; Yoshihiro Oishi; Takeshi Kanashima

1997-01-01

401

Piezoelectricity and ferroelectricity of cellular polypropylene electrets films characterized by piezoresponse force microscopy  

NASA Astrophysics Data System (ADS)

Cellular electrets polymer is a new ferroelectret material exhibiting large piezoelectricity and has attracted considerable attentions in researches and industries. Property characterization is very important for this material and current investigations are mostly on macroscopic properties. In this work, we conduct nanoscale piezoelectric and ferroelectric characterizations of cellular polypropylene (PP) films using piezoresponse force microscopy (PFM). First, both the single-frequency PFM and dual-frequency resonance-tracking PFM testings were conducted on the cellular PP film. The localized piezoelectric constant d33 is estimated to be 7-11pC/N by correcting the resonance magnification with quality factor and it is about one order lower than the macroscopic value. Next, using the switching spectroscopy PFM (SS-PFM), we studied polarization switching behavior of the cellular PP films. Results show that it exhibits the typical ferroelectric-like phase hysteresis loops and butterfly-shaped amplitude loops, which is similar to that of a poly(vinylidene fluoride) (PVDF) ferroelectric polymer film. However, both the phase and amplitude loops of the PP film are intensively asymmetric, which is thought to be caused by the nonzero remnant polarization after poling. Then, the D-E hysteresis loops of both the cellular PP film and PVDF film were measured by using the same wave form as that used in the SS-PFM, and the results show significant differences. Finally, we suggest that the ferroelectric-like behavior of cellular electrets films should be distinguished from that of typical ferroelectrics, both macroscopically and microscopically.

Miao, Hongchen; Sun, Yao; Zhou, Xilong; Li, Yingwei; Li, Faxin

2014-08-01

402

Ferroelectric Thin-Film Capacitors As Ultraviolet Detectors  

NASA Technical Reports Server (NTRS)

Advantages include rapid response, solar blindness, and relative invulnerability to ionizing radiation. Ferroelectric capacitor made to function as photovoltaic detector of ultraviolet photons by making one of its electrodes semitransparent. Photovoltaic effect exploited more fully by making Schottky barrier at illuminated semitransparent-electrode/ferroelectric interface taller than Schottky barrier at other electrode/ferroelectric interface.

Thakoor, Sarita

1995-01-01

403

Real Space Phase Field Simulations of Ferroelectric Materials  

E-print Network

properties. In these applications, ferroelectrics often have com- plex geometries and function under complexReal Space Phase Field Simulations of Ferroelectric Materials Submitted in partial fulfillment-Dian Fellowship and Pittsburgh Supercomputer Center. iii #12;Abstract Ferroelectric perovskites are used

Dayal, Kaushik

404

A Stress-Dependent Hysteresis Model for Ferroelectric Materials  

E-print Network

exploiting ferroelectric compounds -- e.g., PZT, PLZT and PMN -- offer unique actuator and sensorA Stress-Dependent Hysteresis Model for Ferroelectric Materials Brian L. Ball 1 , Ralph C. Smith 2 models which characterize the fer- roelastic switching mechanisms inherent to ferroelectric materials

405

Ferroelectric sources and their application to pulsed power: a review  

Microsoft Academic Search

We present in this review an account of recent research into the use of ferroelectrics as electron beam sources for pulsed power applications. The work is reviewed according to the ferroelectric material used and the switching process employed. Most of the current research uses PLZT or PZT, which can be ferroelectric, antiferroelectric, or paraelectric depending on the stoichiometry. Switching is

Charles B. Fleddermann; John A. Nation

1997-01-01

406

Critical thickness for ferroelectricity in perovskite ultrathin films  

Microsoft Academic Search

The integration of ferroelectric oxide films into microelectronic devices, combined with the size reduction constraints imposed by the semiconductor industry, have revived interest in the old question concerning the possible existence of a critical thickness for ferroelectricity. Current experimental techniques have allowed the detection of ferroelectricity in perovskite films down to a thickness of 40Å (ten unit cells), ref. 3.

Javier Junquera; Philippe Ghosez

2003-01-01

407

Method for the estimation of the total displacement of ferroelectric actuators under mixed thermal and electrical loading  

Microsoft Academic Search

The temperature behavior of the displacement of ferroelectric actuators, when operating at varying temperature, is affected by several factors. First of all, there are changes in field induced strain with temperature. However, the total displacement of an actuator depends also on the poling strain and strain from thermal expansion. These two effects are coupled, because thermal expansion is anisotropic and

Hans Kungl; Michael J. Hoffmann

2008-01-01

408

Nanoscale phenomena in ferroelectric thin films  

NASA Astrophysics Data System (ADS)

Ferroelectric materials are a subject of intense research as potential candidates for applications in non-volatile ferroelectric random access memories (FeRAM), piezoelectric actuators, infrared detectors, optical switches and as high dielectric constant materials for dynamic random access memories (DRAMs). With current trends in miniaturization, it becomes important that the fundamental aspects of scaling of ferroelectric and piezoelectric properties in these devices be studied thoroughly and their impact on the device reliability assessed. In keeping with this spirit of miniaturization, the dissertation has two broad themes: (a) Scaling of ferroelectric and piezoelectric properties and (b) The key reliability issue of retention loss. The thesis begins with a look at results on scaling studies of focused-ion-beam milled submicron ferroelectric capacitors using a variety of scanning probe characterization tools. The technique of piezoresponse microscopy, which is rapidly becoming an accepted form of domain imaging in ferroelectrics, has been used in this work for another very important application: providing reliable, repeatable and quantitative numbers for the electromechanical properties of submicron structures milled in ferroelectric films. This marriage of FIB and SPM based characterization of electromechanical and electrical properties has proven unbeatable in the last few years to characterize nanostructures qualitatively and quantitatively. The second half of this dissertation focuses on polarization relaxation in FeRAMs. In an attempt to understand the nanoscale origins of back-switching of ferroelectric domains, the time dependent relaxation of remnant polarization in epitaxial lead zirconate titanate (PbZr0.2Ti0.8O 3, PZT) ferroelectric thin films (used as a model system), containing a uniform 2-dimensional grid of 90° domains (c-axis in the plane of the film) has been examined using voltage modulated scanning force microscopy. A novel approach of imaging domains with polarization within the plane of the film has been used in this work. Relaxation is seen to occur through the nucleation and growth of reverse domains, which subsequently coalesce and consume the reversed region as a function of time. Results on the effect of local curvature, faceting, and pinning of 180° domain walls on relaxation kinetics are presented. Following the experimental observations, a model for the growth of the reversed domains has been formulated based on the thermo-activated overcoming of pinning sites in these materials. (Abstract shortened by UMI.)

Ganpule, Chandan S.

409

Local bias induced ferroelectricity in manganites with competing charge and orbital order states.  

PubMed

Perovskite-type manganites, such as Pr1-xCaxMnO3, La1-xCaxMnO3 and La1-xSrxMnO3 solid solutions, are set forth as a case study of ferroelectricity formation mechanisms associated with the appearance of site- and bond-centered orbital ordering which breaks structural inversion symmetry. Even though the observation of macroscopic ferroelectricity may be hindered by the finite conductivity of manganites, polarization can still exist in nanoscale volumes. We use Piezoresponse Force Microscopy to probe local bias induced modifications of electrical and electromechanical properties at the manganite surface. Clear bias-induced piezocontrast and local hysteresis loops are observed for La0.89Sr0.11MnO3 and Pr0.60Ca0.40MnO3 compounds providing convincing evidence of the existence of locally induced polar states well above the transition temperature of the CO phase, while the reference samples without CO behavior show no ferroelectric-like response. Such coexistence of ferroelectricity and magnetism in manganites due to the charge ordering (CO) under locally applied electric field opens up a new pathway to expand the phase diagrams of such systems and to achieve spatially localized multiferroic effects with a potential to be used in a new generation of memory cells and data processing circuits. PMID:24477353

Figueiras, Fábio G N; Bdikin, Igor K; Amaral, Vitor B S; Kholkin, Andrei L

2014-03-14

410

Electrical properties of NaSr2Nb5O15 ferroelectric ceramic  

NASA Astrophysics Data System (ADS)

Since the discovery of ferroelectricity, tungsten bronze (TB) ferroelectrics has been a rapid progress in search of new TB-type materials for applications such as capacitors, actuators, transducers, ferroelectric random access memory and display technologies. The materials with TB structure have potential advantages for devices because of their high dielectric constant and low tangent loss. In view of the above importance we have studied the electrical properties of NaSr2Nb5O15 (NSN) ferroelectric ceramic. The polycrystalline NaSr2Nb5O15 (NSN) was prepared by mixed oxide method at high temperature. Electrical properties of NSN have been studied using complex impedance spectroscopy (CIS) with wide range of frequency (10^2-10^6 Hz) and temperature. The complex impedance plot reveals the main contribution of bulk effect. The bulk resistance has been decreased with rise in temperature. The negative temperature coefficient of resistance (NTCR) manifests a semiconductor like behavior. The ac conductivity spectrum was found to obey Jonscher's universal power law.

Behera, Banarji; Pradhan, Nihar; Nayak, P.

2012-02-01

411

Scanning pyroelectric microscopy for characterizing large-area printed ferroelectric sensors on the nanoscale  

NASA Astrophysics Data System (ADS)

This work demonstrates a novel surface scanning method for the quantitative determination of the local pyroelectric coefficient in ferroelectric thin films. Such films find application in flexible and large-area printed ferroelectric sensors for gesture-controlled non-touch human-machine interface devices. The method is called Pyroelectric Scanning Probe Microscopy (PyroSPM)[1] and allows generating a map of the pyroelectric response with very high spatial resolution. In domains of previously aligned dipole moments small heat fluctuations are achieved by laser diode excitation from the bottom side thus inducing changes in the surface potential due to the pyroelectric effect. Simultaneously, the surface potential variations are detected by scanning surface potential microscopy thus forming the base for the pyroelectric coefficient map. The potential of the method is demonstrated on the basis of ferroelectric semi-crystalline copolymer thin films yielding local maxima of the pyroelectric coefficients around 40µC/m2K. Another promising feature of PyroSPM is the ability to visualize "screened" polarization thus enabling in-depth profiling of polarization distributions and domain formation and to study the composition dependence and the time and frequency behavior of ferroelectric nano-domains.

Stadlober, Barbara; Groten, Jonas; Zirkl, Martin; Haase, Anja; Sawatdee, A.; Scheipl, G.

2012-10-01

412

Enhanced energy harvesting in commercial ferroelectric materials  

NASA Astrophysics Data System (ADS)

Ferroelectric materials are used in a number of applications ranging from simple sensors and actuators to ferroelectric random access memories (FRAMs), transducers, health monitoring system and microelectronics. The multiphysical coupling ability possessed by these materials has been established to be useful for energy harvesting applications. However, conventional energy harvesting techniques employing ferroelectric materials possess low energy density. This has prevented the successful commercialization of ferroelectric based energy harvesting systems. In this context, the present study aims at proposing a novel approach for enhanced energy harvesting using commercially available ferroelectric materials. This technique was simulated to be used for two commercially available piezoelectric materials namely PKI-552 and APCI-840, soft and hard lead-zirconate-titanate (PZT) pervoskite ceramics, respectively. It was observed that a maximum energy density of 348 kJm-3cycle-1 can be obtained for cycle parameters of (0-1 ton compressive stress and 1-25 kV.cm-1 electric field) using APCI-840. The reported energy density is several hundred times larger than the maximum energy density reported in the literature for vibration harvesting systems.

Patel, Satyanarayan; Chauhan, Aditya; Vaish, Rahul

2014-04-01

413

Confinement of ferroelectric domain-wall motion at artificially formed conducting-nanofilaments in epitaxial BiFeO3 thin films.  

PubMed

We report confinement of ferroelectric domain-wall motion at conducting-nanofilament wall in epitaxial BiFeO3 thin film on Nb-doped SrTiO3 substrate. The BiFeO3 film exhibited well-defined ferroelectric response and unipolar resistive switching behavior. We artificially formed conducting-nanofilaments in the BiFeO3 via conducting atomic force microscope techniques. The conducting-nanofilament wall, which does not possess any ferroelectric polarization, is then able to block domain propagation. Consequently, we demonstrate that the domain-wall motion is effectively confined within the conducting-nanofilament wall during polarization switching. This significant new insight potentially gives an opportunity for the artificial manipulation of nanoscale ferroelectric domain. PMID:24749974

Kim, Woo-Hee; Son, Jong Yeog; Jang, Hyun Myung

2014-05-14

414

Dielectric relaxation in pseudo-one-dimensional ferroelectric CsD2PO4  

Microsoft Academic Search

Dielectric dispersion in pseudo-one-dimensional hydrogen-bonded ferroelectric CsD2PO4 was measured in the frequency range from 100 kHz to 2 GHz for temperatures between -13 and 30°C. The observed relaxation is monodispersive in the paraelectric phase, except in the vicinity of the transition. The static dielectric constant ?s shows classical critical behavior, with the critical coefficient gamma=1. The relaxation frequency f? is

A. Levstik; B. Zeks; I. Levstik; H. G. Unruh; G. Luther; H. Roemer

1983-01-01

415

Ferroelectric properties of triglycine sulfate crystals with a nonuniform distribution of chromium impurities  

Microsoft Academic Search

The specific features of the ferroelectric behavior of triglycine sulfate crystals with a nonuniform distribution of chromium\\u000a impurities are analyzed. It is demonstrated that the dielectric hysteresis loops of the samples exhibit large shifts both\\u000a along the polarization and electric field directions. The results obtained are well explained within the phenomenological\\u000a approach with due regard for the gradient term in

V. N. Shut; I. F. Kashevich; S. R. Syrtsov

2008-01-01

416

Magnetic field controlled reversal of ferroelectric polarization in conical spin ordered multiferroics: Monte Carlo simulation  

Microsoft Academic Search

To understand the fascinating multiferroicity observed in CoCr2O4, Monte Carlo simulation is performed on a three-dimensional spinel lattice with classical Heisenberg spins. The conical spin order is confirmed to be the origin of the peculiar magnetoelectric behavior with coexisting magnetization and ferroelectric polarization. Furthermore, the simultaneous reversals of magnetization and polarization controlled by the external magnetic field are reproduced, consisting

Xiaoyan Yao; Veng Cheong Lo; Jun-Ming Liu

2009-01-01

417

Microscopic mechanisms for improper ferroelectricity in multiferroic perovskites: a theoretical review  

Microsoft Academic Search

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

Silvia Picozzi; Kunihiko Yamauchi; Ivan A. Sergienko; Cengiz Sen; Biplab Sanyal; Elbio R Dagotto

2008-01-01

418

Development and polarization of ferroelectric polymer gauges, for dynamical acceleration experiments, as those in ballistics shocks  

NASA Astrophysics Data System (ADS)

Studies concerning the development and polarization of ferroelectric polymer gages for acceleration measurements are summarized. The acceleration intensities may reach 300,000 g. Polyvinylidene fluoride films of 40 microns, of polarized active surface between 1 and 25 sq mm, are obtained. The gages piezoelectric coefficient is about 48 pC/N. The accelerometer's design is given and the electrical and mechanical parameters are calculated. The accelerometer's behavior in a Hopkinson system is analyzed and the results are given.

Bauer, F.; Harnischmacher, K.; Riha, J.

1988-08-01

419

Enhancement of the electromechanical response in ferroelectric ceramics by design  

E-print Network

It is demonstrated based on continuum mechanics modeling and simulation that it is possible to obtain polycrystalline ceramic ferroelectric materials which beggars single crystals in electromechanical properties. The local inhomogeneities at the ferroelectric domain-scale level due to spontaneous polarization and the underlying anisotropy are taken into consideration in the framework of mathematical homogenization of physical properties in ferroelectric materials. The intrinsic randomness of the spatial distribution of polarization is shown to be judiciously employed for the design of better polycrystalline ferroelectrics. The noncollinear rotation of the net polarization-vectors embedded in crystallites of the ceramic ferroelectrics is demonstrated to play the key role in the enhancement of physical properties.

Jayachandran, K P; Rodrigues, H C; 10.1063/1.3089216

2010-01-01

420

Diisopropylammonium Bromide Is a High-Temperature Molecular Ferroelectric Crystal  

NASA Astrophysics Data System (ADS)

Molecular ferroelectrics are highly desirable for their easy and environmentally friendly processing, light weight, and mechanical flexibility. We found that diisopropylammonium bromide (DIPAB), a molecular crystal processed from aqueous solution, is a ferroelectric with a spontaneous polarization of 23 microcoulombs per square centimeter [close to that of barium titanate (BTO)], high Curie temperature of 426 kelvin (above that of BTO), large dielectric constant, and low dielectric loss. DIPAB exhibits good piezoelectric response and well-defined ferroelectric domains. These attributes make it a molecular alternative to perovskite ferroelectrics and ferroelectric polymers in sensing, actuation, data storage, electro-optics, and molecular or flexible electronics.

Fu, Da-Wei; Cai, Hong-Ling; Liu, Yuanming; Ye, Qiong; Zhang, Wen; Zhang, Yi; Chen, Xue-Yuan; Giovannetti, Gianluca; Capone, Massimo; Li, Jiangyu; Xiong, Ren-Gen

2013-01-01

421

Effective Nonlinear Behavior of Electrostrictive Multiphase Composites: A  

E-print Network

electrostrictive strain in the order of 0.1% [2] that can be used in actuator applications. A detailed review that links the macroscopic behavior of ferroelectric polymer-based electrostrictive composites

Yu, Wenbin

422

Theory of coexistence of superconductivity and ferroelectricity  

NASA Astrophysics Data System (ADS)

An investigation of the coexistence and competition of ferroelectricity and superconductivity is reported. We show that the starting Hamiltonian of a previous study by Birman and Weger [Phys. Rev. B 64, 174503 (2001)] can be exactly diagonalized. The result differs significantly from mean-field theory. A Hamiltonian with a different realization of the coupling between ferroelectricity and superconductivity is proposed. We report the results for mean-field theory applied to this Hamiltonian. We find that the order parameters are strongly affected by this coupling. The “Matthias conjecture” [Ferroelectricity, edited by E. Weller (Elsevier, New York, 1976)] that each of these order parameters tends to suppress the other is supported by our results.

Krivolapov, Y.; Mann, A.; Birman, Joseph L.

2007-03-01

423

Multiferroics: a magnetic twist for ferroelectricity.  

PubMed

Magnetism and ferroelectricity are essential to many forms of current technology, and the quest for multiferroic materials, where these two phenomena are intimately coupled, is of great technological and fundamental importance. Ferroelectricity and magnetism tend to be mutually exclusive and interact weakly with each other when they coexist. The exciting new development is the discovery that even a weak magnetoelectric interaction can lead to spectacular cross-coupling effects when it induces electric polarization in a magnetically ordered state. Such magnetic ferroelectricity, showing an unprecedented sensitivity to ap plied magnetic fields, occurs in 'frustrated magnets' with competing interactions between spins and complex magnetic orders. We summarize key experimental findings and the current theoretical understanding of these phenomena, which have great potential for tuneable multifunctional devices. PMID:17199121

Cheong, Sang-Wook; Mostovoy, Maxim

2007-01-01

424

Negative differential conductivity in thin ferroelectric films  

NASA Astrophysics Data System (ADS)

A phenomenon of negative differential conductivity in ferroelectric thin films is discussed. We proposed that the reason is polarization recovery current arising at current-voltage I(V) measurements as a result of polarization relaxation after pre-polarization of ferroelectric film. Simulation of this current by Weibull distribution provides a good correlation with the experimental data. The obtained values of the recovered polarization Prec and the field strength Erec at which the recovery polarization current reaches maximum do not depend on the voltage sweep rate and are well correlated with the values of polarization relaxation Prel and coercive field strength Ec obtained from dielectric hysteresis loop. It is shown that the current density due to polarization recovery Jrec may exceed by about an order the ohmic current density J? in ferroelectric film at Ec.

Podgorny, Yury; Vorotilov, Konstantin; Sigov, Alexander

2014-11-01

425

Modified Johnson model for ferroelectric lead lanthanum zirconate titanate at very high fields and below Curie temperature.  

SciTech Connect

A modified Johnson model is proposed to describe the nonlinear field dependence of the dielectric constant ({var_epsilon}-E loop) in ferroelectric materials below the Curie temperature. This model describes the characteristic ferroelectric 'butterfly' shape observed in typical {var_epsilon}-E loops. The predicted nonlinear behavior agreed well with the measured values in both the low- and high-field regions for lead lanthanum zirconate titanate films. The proposed model was also validated at different temperatures below the ferroelectric-to-paraelectric Curie point. The anharmonic coefficient in the model decreased from 6.142 x 10{sup -19} cm{sup 2}/V{sup 2} to 2.039 x 10{sup -19} cm{sup 2}/V{sup 2} when the temperature increased from 25 C to 250 C.

Narayanan, M.; Tong, S.; Ma, B.; Liu, S.; Balachandran, U. (Energy Systems)

2012-01-01

426

Are lithium niobate (LiNbO3) and lithium tantalate (LiTaO3) ferroelectrics bioactive?  

PubMed

The use of functional materials, such as ferroelectrics, as platforms for tissue growth in situ or ex situ, is new and holds great promise. But the usage of materials in any bioapplication requires information on biocompatibility and desirably on bioactive behavior when bone tissue engineering is envisaged. Both requirements are currently unknown for many ferroelectrics. Herein the bioactivity of LiNbO3 and LiTaO3 is reported. The formation of apatite-like structures on the surface of LiNbO3 and LiTaO3 powders after immersion in simulated body fluid (SBF) for different soaking periods indicates their bioactive potential. The mechanism of apatite formation is suggested. In addition, the significant release of lithium ions from the ferroelectric powders in the very first minutes of soaking in SBF is examined and ways to overcome this likely hurdle addressed. PMID:24863240

Vilarinho, Paula Maria; Barroca, Nathalie; Zlotnik, Sebastian; Félix, Pedro; Fernandes, Maria Helena

2014-06-01

427

Ferroelectric Cathodes in Transverse Magnetic Fields  

SciTech Connect

Experimental investigations of a planar ferroelectric cathode in a transverse magnetic field up to 3 kGs are presented. It is shown that the transverse magnetic field affects differently the operation of ferroelectric plasma cathodes in ''bright'' and ''dark'' modes in vacuum. In the ''bright'' mode, when the surface plasma is formed, the application of the transverse magnetic field leads to an increase of the surface plasma density. In the ''dark'' mode, the magnetic field inhibits the development of electron avalanches along the surface, as it does similarly in other kinds of surface discharges in the pre-breakdown mode.

Alexander Dunaevsky; Yevgeny Raitses; Nathaniel J. Fisch

2002-07-29

428

Ferroelectric plasma thruster for microspacecraft propulsion  

NASA Astrophysics Data System (ADS)

This paper presents a technology in microthruster design: the ferroelectric plasma thruster (FEPT). The FEPT utilizes an applied rf electric field to create plasma on the surface of a ferroelectric dielectric. Acceleration of ions from this plasma provides thrust. Advantages of the FEPT include emission of both electrons and ions leading to self-neutralization, creation of plasma, and acceleration of ions with a single power supply, and application of thrust in a short amount of time. We present the concept of the thruster, operational physics, as well as experimental results demonstrating plasma creation and ion acceleration. These results along with plasma spectroscopy allow us to calculate thruster parameters.

Kemp, Mark A.; Kovaleski, Scott D.

2006-12-01

429

Ferroelectric Material Application: Modeling Ferroelectric Field Effect Transistor Characteristics from Micro to Nano  

NASA Technical Reports Server (NTRS)

All present ferroelectric transistors have been made on the micrometer scale. Existing models of these devices do not take into account effects of nanoscale ferroelectric transistors. Understanding the characteristics of these nanoscale devices is important in developing a strategy for building and using future devices. This paper takes an existing microscale ferroelectric field effect transistor (FFET) model and adds effects that become important at a nanoscale level, including electron velocity saturation and direct tunneling. The new model analyzed FFETs ranging in length from 40,000 nanometers to 4 nanometers and ferroelectric thickness form 200 nanometers to 1 nanometer. The results show that FFETs can operate on the nanoscale but have some undesirable characteristics at very small dimensions.

MacLeod, Todd, C.; Ho, Fat Duen

2006-01-01

430

Probing Polarization Dynamics and Energy Dissipation in Ferroelectric Polymers on the Nanoscale  

NASA Astrophysics Data System (ADS)

Ferroelectric polymers are emerging as prominent materials for ultrasonic actuators, gate materials for non-volatile ferroelectric memories, and energy storage. The nature of ferroelectricity in polymers is significantly different from that in inorganic perovskites, resulting in significant interest to elementary mechanism of switching and the role of local microstructure. In this talk, I briefly delineate Piezoresponse Force Microscopy and Spectroscopy as applied for characterization of Langmuir-Blodgett ferroelectric PVDF polymer films. The slow polarization switching in PVDF can be attributed to the grain-by grain switching mechanism. Recent advances in PFM probing of polarization dynamics and electromechanical energy dissipation are discussed. In particular, switching spectroscopy PFM is used to probe the spatial variability of switching behavior and role of grain boundaries on switching. Local energy dissipation imaging through the changes of the Q-factor of electrically driven cantilever in contact with the surface is developed to study energy losses in the ferroelectric switching processes. In collaboration with Brian J. Rodriguez and Stephen Jesse, Materials Sciences and Technology Division and The Center for Nanophase Materials Sciences, Oak Ridge National Laboratory; Jihee Kim and Steven Ducharme, Department of Physics and Astronomy, Nebraska Center for Materials and Nanoscience University of Nebraska, Lincoln. Research was supported by the U.S. Department of Energy Office of Basic Energy Sciences Division of Materials Sciences and Engineering (SVK, BJR, and SJ) and user proposal of The Center for Nanophase Materials Sciences (JK and SD) and was performed at Oak Ridge National Laboratory which is operated by UT-Battelle, LLC.

Kalinin, Sergei V.

2007-03-01

431

Properties of ferroelectric/ferromagnetic thin film heterostructures  

NASA Astrophysics Data System (ADS)

Ferroelectric/ferromagnetic thin film heterostructures, SrBi2Ta2O9/BaFe12O19 (SBT/BaM), were grown on platinum-coated Si substrates using metal-organic decomposition. X-ray diffraction patterns confirmed that the heterostructures contain only SBT and BaM phases. The microwave properties of these heterostructures were studied using a broadband ferromagnetic resonance (FMR) spectrometer from 35 to 60 GHz, which allowed us to determine gyromagnetic ratio and effective anisotropy field. The FMR linewidth is as low as140 Oe at 58 GHz. In addition, measurements of the effective permittivity of the heterostructures were carried out as a function of bias electric field. All heterostructures exhibit hysteretic behavior of the effective permittivity. These properties indicate that such heterostructures have potential for application in dual electric and magnetic field tunable resonators, filters, and phase shifters.

Chen, Daming; Harward, Ian; Linderman, Katie; Economou, Evangelos; Nie, Yan; Celinski, Zbigniew

2014-05-01

432

Properties of ferroelectric/ferromagnetic thin film heterostructures  

SciTech Connect

Ferroelectric/ferromagnetic thin film heterostructures, SrBi{sub 2}Ta{sub 2}O{sub 9}/BaFe{sub 12}O{sub 19} (SBT/BaM), were grown on platinum-coated Si substrates using metal-organic decomposition. X-ray diffraction patterns confirmed that the heterostructures contain only SBT and BaM phases. The microwave properties of these heterostructures were studied using a broadband ferromagnetic resonance (FMR) spectrometer from 35 to 60 GHz, which allowed us to determine gyromagnetic ratio and effective anisotropy field. The FMR linewidth is as low as140 Oe at 58 GHz. In addition, measurements of the effective permittivity of the heterostructures were carried out as a function of bias electric field. All heterostructures exhibit hysteretic behavior of the effective permittivity. These properties indicate that such heterostructures have potential for application in dual electric and magnetic field tunable resonators, filters, and phase shifters.

Chen, Daming, E-mail: chendaming1986@gmail.com [Center for Magnetism and Magnetic Nanostructures, University of Colorado Colorado Springs, 1420 Austin Bluffs Pkwy, Colorado Springs, Colorado 80918 (United States); State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054 Sichuan (China); Harward, Ian; Linderman, Katie; Economou, Evangelos; Celinski, Zbigniew [Center for Magnetism and Magnetic Nanostructures, University of Colorado Colorado Springs, 1420 Austin Bluffs Pkwy, Colorado Springs, Colorado 80918 (United States); Nie, Yan [Center for Magnetism and Magnetic Nanostructures, University of Colorado Colorado Springs, 1420 Austin Bluffs Pkwy, Colorado Springs, Colorado 80918 (United States); School of Optical and Electronic Information, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, Hubei 430074 (China)

2014-05-07

433

Chemical order and local structure of the lead-free relaxor ferroelectric Na 1 \\/ 2 Bi 1 \\/ 2 TiO 3  

Microsoft Academic Search

The A-site mixed perovskite sodium bismuth titanate (Na1\\/2Bi1\\/2)TiO3 (NBT) is investigated by means of first-principles calculations based on density functional theory. By studying different geometries with varying occupations of the A-site, the influence of chemical order on the thermodynamic stability and local structure is explored. We find that the hybridization of Bi 6sp with O 2p-states leads to stereochemically active

Melanie Gröting; Silke Hayn; Karsten Albe

2011-01-01

434

Ferroelectric-field-effect-enhanced electroresistance in metal/ferroelectric/semiconductor tunnel junctions.  

PubMed

Ferroelectric tunnel junctions (FTJs), composed of two metal electrodes separated by an ultrathin ferroelectric barrier, have attracted much attention as promising candidates for non-volatile resistive memories. Theoretical and experimental works have revealed that the tunnelling resistance switching in FTJs originates mainly from a ferroelectric modulation on the barrier height. However, in these devices, modulation on the barrier width is very limited, although the tunnelling transmittance depends on it exponentially as well. Here we propose a novel tunnelling heterostructure by replacing one of the metal electrodes in a normal FTJ with a heavily doped semiconductor. In these metal/ferroelectric/semiconductor FTJs, not only the height but also the width of the barrier can be electrically modulated as a result of a ferroelectric field effect, leading to a greatly enhanced tunnelling electroresistance. This idea is implemented in Pt/BaTiO3/Nb:SrTiO3 heterostructures, in which an ON/OFF conductance ratio above 10(4), about one to two orders greater than those reported in normal FTJs, can be achieved at room temperature. The giant tunnelling electroresistance, reliable switching reproducibility and long data retention observed in these metal/ferroelectric/semiconductor FTJs suggest their great potential in non-destructive readout non-volatile memories. PMID:23685861

Wen, Zheng; Li, Chen; Wu, Di; Li, Aidong; Ming, Naiben

2013-07-01

435

Generalized Landau model of ferroelectric liquid crystals  

Microsoft Academic Search

Using a generalized Landau type of free-energy density, we develop a theoretical model which, in a unified way, describes the general features of the tilt, polarization, pitch, dielectric susceptibility, and heat capacity of ferroelectric liquid crystals. Rewriting the equations into dimensionless form, we show that six parameters are needed in order to account properly for the temperature dependence of the

T. Carlsson; B. Zeks; A. Levstik; C. Filipic; I. Levstik; R. Blinc

1987-01-01

436

Ferroelectric control of a Mott insulator.  

PubMed

The electric field control of functional properties is an important goal in oxide-based electronics. To endow devices with memory, ferroelectric gating is interesting, but usually weak compared to volatile electrolyte gating. Here, we report a very large ferroelectric field-effect in perovskite heterostructures combining the Mott insulator CaMnO3 and the ferroelectric BiFeO3 in its "supertetragonal" phase. Upon polarization reversal of the BiFeO3 gate, the CaMnO3 channel resistance shows a fourfold variation around room temperature, and a tenfold change at ~200 K. This is accompanied by a carrier density modulation exceeding one order of magnitude. We have analyzed the results for various CaMnO3 thicknesses and explain them by the electrostatic doping of the CaMnO3 layer and the presence of a fixed dipole at the CaMnO3/BiFeO3 interface. Our results suggest the relevance of ferroelectric gates to control orbital- or spin-ordered phases, ubiquitous in Mott systems, and pave the way toward efficient Mott-tronics devices. PMID:24089020

Yamada, Hiroyuki; Marinova, Maya; Altuntas, Philippe; Crassous, Arnaud; Bégon-Lours, Laura; Fusil, Stéphane; Jacquet, Eric; Garcia, Vincent; Bouzehouane, Karim; Gloter, Alexandre; Villegas, Javier E; Barthélémy, Agnès; Bibes, Manuel

2013-01-01

437

Ferroelectric Devices Emit Charged Particles and Radiation  

NASA Technical Reports Server (NTRS)

Devices called solid-state ferroelectric- based sources (SSFBSs) are under development as sources of electrons, ions, ultraviolet light, and x-rays for diverse applications in characterization and processing of materials. Whereas heretofore it has been necessary to use a different device to generate each of the aforementioned species of charged particles or radiation, a single SSFBS can be configured and operated to selectively generate any of the species as needed using a single source. Relative to comparable prior sources based, variously, on field emission, thermionic emission, and gaseous discharge plasmas, SSFBSs demand less power, and are compact and lightweight. An SSFBS exploits the unique physical characteristics of a ferroelectric material in the presence of a high-frequency pulsed electric field. The basic building block of an SSFBS is a ferroelectric cathode -- a ferroelectric wafer with a solid electrode covering its rear face and a grid electrode on its front face (see figure). The application of a voltage pulse -- typically having amplitude of several kilovolts and duration of several nanoseconds -- causes dense surface plasma to form near the grid wires on the front surface.

Bar-Cohen, Yoseph; Sherrit, Stewart; Bao, Xiaoqi; Felsteiner, Joshua; Karsik, Yakov

2005-01-01

438

Series resonance circuit with ferroelectric capacitor  

Microsoft Academic Search

A series resonance circuit under sinuousoidal driving is investigated experimentally. The inductance consists of an air coil. The capacitance is made up of a ferroelectric material that introduces its nonlinear dielectric properties into the circuit. The dynamical system linear coil-nonlinear capacaitor shows an interesting behaviour. The phase portrait differs in general from the ellipse of the harmonic oscillator. For appropriate

Eckart Brauer; Horst Beige; Leci Flepp; Mareike Klee

1993-01-01

439

Theory of prospective tetrahedral perovskite ferroelectrics  

E-print Network

Using first-principles methods, we predict the energy landscape and ferroelectric states of double perovskites of the form AA$'$BB$'$O$_6$ in which the atoms on both the A and B sites are arranged in rock-salt order. While we are not aware of compounds that occur naturally in this structure, we argue that they might be realizable by directed synthesis. The high-symmetry structure formed by this arrangement belongs to the tetrahedral $F\\bar{4}3m$ space group. If a ferroelectric instability occurs, the energy landscape will tend to have minima with the polarization along tetrahedral directions, leading to a rhombohedral phase, or along Cartesian directions, leading to an orthorhombic phase. We find that the latter scenario applies to CaBaTiZrO$_6$ and KCaZrNbO$_6$, which are weakly ferroelectric, and the former one applies to PbSnTiZrO$_6$, which is strongly ferroelectric. The results are modeled with a fourth- or fifth-order Landau-Devonshire expansion, providing good agreement with the first-principles calcul...

Roy, Anindya

2010-01-01

440

Graphene Ferroelectric Heterostructures Santosh Raghavan1  

E-print Network

Graphene Ferroelectric Heterostructures Santosh Raghavan1 , Dr. Jean-Savin Heron2 , Dr. Igor] Laboratory of Nanoscale Electronics and Structures, IEL, EPFL S D1 2 Doped Silicon SiO2 Graphene 3 4 1 2S D L Introduction Working Principle Graphene PVDF (-TrFE) PFM Measurements Retention Measurements Conclusion

Dalang, Robert C.

441

Ferroelectric polarization reversal via successive ferroelastic transitions  

NASA Astrophysics Data System (ADS)

Switchable polarization makes ferroelectrics a critical component in memories, actuators and electro-optic devices, and potential candidates for nanoelectronics. Although many studies of ferroelectric switching have been undertaken, much remains to be understood about switching in complex domain structures and in devices. In this work, a combination of thin-film epitaxy, macro- and nanoscale property and switching characterization, and molecular dynamics simulations are used to elucidate the nature of switching in PbZr0.2Ti0.8O3 thin films. Differences are demonstrated between (001)-/(101)- and (111)-oriented films, with the latter exhibiting complex, nanotwinned ferroelectric domain structures with high densities of 90° domain walls and considerably broadened switching characteristics. Molecular dynamics simulations predict both 180° (for (001)-/(101)-oriented films) and 90° multi-step switching (for (111)-oriented films) and these processes are subsequently observed in stroboscopic piezoresponse force microscopy. These results have implications for our understanding of ferroelectric switching and offer opportunities to change domain reversal speed.

Xu, Ruijuan; Liu, Shi; Grinberg, Ilya; Karthik, J.; Damodaran, Anoop R.; Rappe, Andrew M.; Martin, Lane W.

2015-01-01

442

Radiation Damage Effects in Ferroelectric Triglycine Sulfate  

Microsoft Academic Search

Peculiar changes in the ferroelectric hysteresis loops of single crystals of triglycine sulfate result when the crystals are subjected to ionizing radiations (x-rays and electrons). Fully polarized crystals develop hysteresis loops biased along the field axis while partially polarized crystals develop double-loop patterns, each subsidiary loop being biased to the same extent but in opposite directions. The biased loops retain

A. G. Chynoweth

1959-01-01

443

Ferroelectric polarization reversal via successive ferroelastic transitions.  

PubMed

Switchable polarization makes ferroelectrics a critical component in memories, actuators and electro-optic devices, and potential candidates for nanoelectronics. Although many studies of ferroelectric switching have been undertaken, much remains to be understood about switching in complex domain structures and in devices. In this work, a combination of thin-film epitaxy, macro- and nanoscale property and switching characterization, and molecular dynamics simulations are used to elucidate the nature of switching in PbZr0.2Ti0.8O3 thin films. Differences are demonstrated between (001)-/(101)- and (111)-oriented films, with the latter exhibiting complex, nanotwinned ferroelectric domain structures with high densities of 90° domain walls and considerably broadened switching characteristics. Molecular dynamics simulations predict both 180° (for (001)-/(101)-oriented films) and 90° multi-step switching (for (111)-oriented films) and these processes are subsequently observed in stroboscopic piezoresponse force microscopy. These results have implications for our understanding of ferroelectric switching and offer opportunities to change domain reversal speed. PMID:25344784

Xu, Ruijuan; Liu, Shi; Grinberg, Ilya; Karthik, J; Damodaran, Anoop R; Rappe, Andrew M; Martin, Lane W

2015-01-01

444

A hybrid ferroelectric-flash memory cells  

NASA Astrophysics Data System (ADS)

A ferroelectric-flash (F-flash) memory cells having a metal-ferroelectric-nitride-oxynitride-silicon structure are demonstrated, and the ferroelectric materials were perovskite-dominated Pb(Zr,Ti)O3 (PZT) crystallized by Pt gate electrode. The PZT thin-film as a blocking layer improves electrical and memorial performance where programming and erasing mechanism are different from the metal-ferroelectric-insulator-semiconductor device or the conventional silicon-oxide-nitride-oxide-silicon device. F-flash cells exhibit not only the excellent electrical transistor performance, having 442.7 cm2 V-1 s-1 of field-effect mobility, 190 mV dec-1 of substhreshold slope, and 8 × 105 on/off drain current ratio, but also a high reliable memory characteristics, having a large memory window (6.5 V), low-operating voltage (0 to -5 V), faster P/E switching speed (50/500 ?s), long retention time (>10 years), and excellent fatigue P/E cycle (>105) due to the boosting effect, amplification effect, and energy band distortion of nitride from the large polarization. All these characteristics correspond to the best performances among conventional flash cells reported so far.

Park, Jae Hyo; Byun, Chang Woo; Seok, Ki Hwan; Kim, Hyung Yoon; Chae, Hee Jae; Lee, Sol Kyu; Son, Se Wan; Ahn, Donghwan; Joo, Seung Ki

2014-09-01

445

High permittivity ferroelectric actuators for radar applications  

Microsoft Academic Search

We report a new method of fabricating thermal bimorph actuators utilizing high permittivity ferroelectric thin films. This device is the first known thermal cantilever actuator employing barium titanate (BaTiO3) for RF applications. Compared to electrostatic actuators, this MEMS structure is designed to handle high RF transmitted power while maintaining a high capacitance ratio due to the high permittivity of the

J. Ficklen; J. Weaver; C. Chen; A. A. Ayon

2009-01-01

446

Piezoelectricity and Electrostriction in Ferroelectric Actuators  

Microsoft Academic Search

Large amplitude driving of ferroelectric actuators has been investigated. Displacement xi, electric charge Q and current I were measured with varying alternating voltage VAC at various frequencies f (120, 500 and 1000 Hz) under voltage bias Vbias (0 to 75 V). Effective piezoelectric and dielectric constants were evaluated from initial slopes of xi and Q vs VAC, respectively. It is

Atsushi Kurihara; Koji Nomura; Ken-ichi Hirota; Takuro Ikeda

1992-01-01

447

Ferroelectric Materials for Electromechanical Transducer Applications  

Microsoft Academic Search

Many advantages of ferroelectric compositions in the lead zirconate:lead titanate (PZT) solid solutions for both sensing and actuation are explored. The state of understanding of both intrinsic single domain and extrinsic domain wall and phase boundary contribution to response is described, and the composition manipulations used to modifiy the extrinsic responses explored. In lead magnesium niobate (PMN) based solid solution

Leslie Eric Cross

1995-01-01

448