Charge pumping and pseudopyroelectric effect in active ferroelectric relaxor-type films

Schubring, Norman W.; Mantese, J. V.; Micheli, Adolph L.; Catalan, Antonio B.; Lopez, Richard J.

doi:10.1103/physrevlett.68.1778

Cited by 156 publications

(87 citation statements)

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“…Other ways of creating internal fields include building mesoscale composites, 57 as well as multilayers and graded structures. 58 For example, in a recent study, it was shown that the intrinsic PE and EC properties of PZT could be improved significantly by constructing PZT/SrTiO3 heterostructures. 59 Because the internal dc field clamps the polarizability, reductions in the dielectric constant by a factor of 10 or more are, in principle, possible.…”

Section: Device and System Considerations For Materials Selection Andmentioning

confidence: 99%

Next-generation electrocaloric and pyroelectric materials for solid-state electrothermal energy interconversion

Mantese²,

et al. 2014

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Thin-film electrocaloric and pyroelectric electrothermal interconversion energy sources have recently emerged as viable means for primary and auxiliary solid-state cooling and power generation. Two significant advances have facilitated this development: (1) the formation of high-quality polymeric and ceramic thin films with figures of merit that project system-level performance as a large percentage of Carnot efficiency and (2) the ability of these newer materials to support larger electric fields, thereby permitting operation at higher voltages.This makes the power electronic architectures more favorable for thermal to electric interconversion. Current research targets to adequately address commercial device needs include reduction of parasitic losses, increases in mechanical robustness, and the ability to form nearly free-standing elements with thicknesses in the range of 1-10 m. This article describes the current state-ofthe-art materials, thermodynamic cycles, and device losses and points toward potential lines of research that would lead to substantially better figures of merit for electrothermal interconversion.Keywords: Material type-polymer (143), Material type-ceramic (121), Functionality-energy generation (189), , Material form-film (231), Transport-ferroelectricity (288) Fundamentals of ferroelectrics materials: Pyroelectrics and ElectrocaloricsIt has long been known that, when heated, materials such as the borosilicate tourmaline have the ability to attract objects such as pieces of feather, pollen, and cloth. This is due to the appearance of a surface charge in response to a temperature change. The history of this phenomenon, which is known as the pyroelectric effect (PE), was charted by Lang, 1 from its first description by Dielectrics whose structures possess both a unique axis of symmetry and lack a center of symmetry (i.e., that are "polar") display a spontaneous polarization (PS) and will exhibit a PE due to temperature-induced changes in PS. MRS BulletinThese variations in PS result in uncompensated charge appearing along surfaces that have a component normal to the polar axis, generating a net voltage across the dielectric. If the surfaces are provided with electrodes that are connected through an external circuit, this surface charge can cause a current to flow, potentially resulting in useful work. In the absence of an applied electric field or applied stress, the pyroelectric coefficient p(T) is defined as the rate of change of spontaneous polarization with temperature such that p(T) = dPS/dT. If electrodes are applied to the major faces perpendicular to the polar axis, as illustrated in Figure 1a, and the temperature is changed at a rate dT/dt, then the short-circuitThe converse of the pyroelectric effect is called the electrocaloric effect (ECE; see Figure 1b). Here, an electric field applied to a polar dielectric causes a change in temperature in the material. Conceptually, the ECE is somewhat harder to grasp than the PE, but it is analogous to the changes in temperature and en...

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Section: Device and System Considerations For Materials Selection Andmentioning

confidence: 99%

Next-generation electrocaloric and pyroelectric materials for solid-state electrothermal energy interconversion

Mantese²,

et al. 2014

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“…Our theoretical investigation of SCLC began with a study of the well-known phenomenon of polarization offsets in compositionally graded ferroelectric films (Bao et al 2000a(Bao et al , 2000b(Bao et al , 2000c(Bao et al , 2001a(Bao et al , 2001bBouregba et al, 2003;Brazier et al, 1998;Chen et al, 1999;Mantese et al, 1997;Matsuzaki & Funakubo, 1999;Schubring et al, 1992). Ferroelectric materials are materials that generally exhibit nonlinear, hysteretic D-E or P-E relations, where D is the electric displacement, P is the polarization and E is the electric field.…”

Section: Polarization Offsets In Graded Ferroelectrics and The Need Fmentioning

confidence: 99%

“…In a later study (Zhou et al, 2005a), we have employed this new conductivity expression to understand the origin of imprint effect in homogeneous ferroelectric films. In this Book Chapter, we will (i) review the original derivation of the Mott-Gurney law (Coelho, 1979;Pope & Swemberg, 1998), (ii) review the original problem of polarization offsets in compositionally graded ferroelectric films (Schubring et al, 1992) and explain why such a new local conductivity expression was needed in our theoretical investigation, (iii) review our original derivation of this general local conductivity expression (Chan et al, 2004), (iv) review our study on the limiting case of zero intrinsic conductivity (Chan et al, 2007;Zhou et al, 2005a), (v) supply the derivation of a general expression, via the mass-action approximation, for the corresponding local diffusion-current density (Chan, unpublished), which incorporates the Einstein relations and takes into account the possible presence of a temperature gradient, (vi) present an alternative derivation of this local conductivity expression (Chan, unpublished) with a detailed theoretical justification of the mass-action approximation, and (vii) discuss, in the concluding section, possible future work as to a better understanding of the mechanism of charge flow in a compositionally graded ferroelectric film as well as of the scope of applicability of the general local conductivity expression.…”

Section: Introductionmentioning

confidence: 99%

“…Due to the limited applicability of the Mott-Gurney law, there has been the need to derive a more general SCLC formula that applies to cases (i) with the simultaneous presence of p-type and n-type free charge-carriers, (ii) with the presence of a small but finite intrinsic conductivity σ in , as well as (iii) with any possible field dependence of the dielectric permittivity ε. In 2003, while we were searching for a theoretical explanation to the well-known experimental observation of polarization offsets (Schubring et al, 1992) in compositionally graded ferroelectric films, we employed the law of mass action to derive a general local conductivity expression for double-carrier-type SCLC in solid dielectrics and showed numerically that SCLC is a possible origin of the observation of polarization offsets in those graded ferroelectric films (Chan et al, 2004). In those graded films, there exist gradients of electric displacements and therefore, according to Gauss' law, a corresponding presence of free space-charge.…”

Section: Introductionmentioning

confidence: 99%

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A General Conductivity Expression for Space-Charge-Limited Conduction in Ferroelectrics and Other Solid Dielectrics

Chan¹

2011

Ferroelectrics - Characterization and Modeling

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“…The unconventional behavior presented by such heterogeneous ferroelectric systems is thought to arise from the polarization nonuniformity imposed by a composition, temperature, or stress gradient. [1][2][3] One of the most notable phenomenon is the large polarization offset along the vertical axis found in the hysteresis loop measurements. Values as large as 420 C/cm 2 were reported for the polarization offset in lead-zirconate-titanate ͑PZT͒ graded structures.…”

Section: Introductionmentioning

confidence: 99%

Effects of polarization and permittivity gradients and other parameters on the anomalous vertical shift behavior of graded ferroelectric thin films

Zhou

Chan

Lam

et al. 2005

Journal of Applied Physics

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We studied theoretically the dependence of the "polarization offset" on various parameters in compositionally graded ferroelectric thin films. Our model adopts the Landau-Khalatnikov equation to describe hysteresis behavior and takes the time-dependent space-charge-limited conductivity into account to investigate the effects of polarization and permittivity gradients, charge mobilities, and thickness in graded ferroelectric thin films. We found that both polarization and permittivity gradients are requisite for the occurrence of offset phenomena. It is also found that larger gradients of remanent polarization and permittivity, a smaller thickness, and a larger charge mobility can generally enhance the effect of vertical offsets. The qualitative agreement between simulation and experiment further supports our previous notion that the asymmetric conduction current arising as a result of the composition gradient is an important factor leading to the polarization offset phenomenon.

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Charge pumping and pseudopyroelectric effect in active ferroelectric relaxor-type films

Cited by 156 publications

References 8 publications

Next-generation electrocaloric and pyroelectric materials for solid-state electrothermal energy interconversion

Next-generation electrocaloric and pyroelectric materials for solid-state electrothermal energy interconversion

A General Conductivity Expression for Space-Charge-Limited Conduction in Ferroelectrics and Other Solid Dielectrics

Effects of polarization and permittivity gradients and other parameters on the anomalous vertical shift behavior of graded ferroelectric thin films

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