Long-Lived Dynamic Heterogeneity in a Relaxor Ferroelectric

Kircher, Oliver; Schiener, B.; Böhmer, Roland

doi:10.1103/physrevlett.81.4520

Cited by 44 publications

(44 citation statements)

References 21 publications

(34 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…From low temperature to high temperature, the shape of the ⌬ ϳ ln( ) curve changes from concave to approximately linear, and then to convex. The aging of the susceptibility of relaxor ferroelectrics can be well fitted with the stretched exponential function: 27,28 t ϭ ϱ ϩK exp͓Ϫ͑t/ ͒ ͔, ͑5͒ where t is the susceptibility at time t. Because the internal field width is zero when tϭ0 and reaches a fixed value when t→ϱ, Kϭ 0 Ϫ ϱ ϭ (0)Ϫ ( e )ϭ⌬ . For many relaxors, the aging time constant is large and the distribution factor is small, and thus exp͓Ϫ(t/ ) ͔ can be approximately expressed as c( , )(ln tϩb) at large times.…”

Section: ͑3͒mentioning

confidence: 99%

Effect of defect-induced internal field on the aging of relaxors

Duan

Wang

et al. 2003

Phys. Rev. B

View full text Add to dashboard Cite

The effect of a defect-induced internal field on the dielectric response of relaxor ferroelectrics is investigated using a Monte Carlo simulation. It was observed that only at a small temperature range near the temperature of the dielectric maximum does the susceptibility decrease markedly due to the internal field. This temperature range increases with enhancing internal field. We found that the susceptibility is almost independent of the internal field width at low internal field width, and then decreases linearly with enhancing internal field width. This dependence of the susceptibility on the internal field width is very similar to the relation of the dielectric constant with logarithmic aging time, which probably suggests a linear dependence of the internal field on the logarithm of the aging time. The frequency dependence of the susceptibility aging is sensitive to the temperature. With increasing temperature, the curve of the susceptibility change against logarithmic frequency varies from concave to approximately linear, and then to convex, which is in agreement with the recent aging rate measurement. Relaxor ferroelectrics ͑relaxors͒ have special dielectric characteristics compared with normal ferroelectrics. A typical relaxor ferroelectric displays a diffuse phase transition, a strong frequency dispersion of the dielectric properties, and an absence of macroscopic polarization at zero electric field. 1 Although the origin of these dielectric features is still controversial, it has been suggested that the presence of polar microregions in nanoscale is crucial to the relaxor behaviors. Various models, such as the dipolar glass model, the quenched random-field model, and the random-bandrandom-field model, have been proposed to account for the unusual physical properties of relaxor ferroelectrics. [2][3][4][5][6] The relatively high dielectric constant and lowtemperature coefficient has led to many successful applications of relaxors such as multilayered capacitors. Due to their influences on the actual applications and the comprehension of the dielectric mechanism, the dielectric aging behaviors of relaxor ferroelectrics have been extensively investigated in the last decade. 7-14 The experimental results have indicated the importance of the defect structure in the aging in this type of material. For example, very little dielectric aging was observed for a carefully prepared pure PMN. However, PMN with Mn and other acceptor dopants shows significant aging. 10 The main characteristic of acceptor dopants is the introduction of O 2Ϫ vacancies, which results in the formation of the oxygen-vacancy-metal-impurity defect dipoles. 7,8 The reorientation and alignment of the defect dipoles with the local nanoscale polar domains lead to the internal field, which provides a pinning to the polar microregion and results in a decrease of the switchable polarization. 15,16 It is widely accepted nowadays that the defect-induced internal field is responsible for the aging behavior in relaxor ferroelectrics, but how the inter...

show abstract

Section: ͑3͒mentioning

confidence: 99%

Effect of defect-induced internal field on the aging of relaxors

Duan

Wang

et al. 2003

Phys. Rev. B

View full text Add to dashboard Cite

show abstract

“…The NSHB technique has been first applied to the study of supercooled liquids. The polarization response of dielectric samples, glycerol and propylene carbonate, was measured after being modified by an ac electric field.[2] More recently, ion-conducting glasses like CKN [3], relaxor ferroelectrics (90PMN-10PT ceramics) [4] and spinglasses (5% Au:Fe) [5] were studied with similar methods. The results have been interpreted as evidence for the existence of spatial heterogeneities.…”

mentioning

confidence: 99%

“…[2] More recently, ion-conducting glasses like CKN [3], relaxor ferroelectrics (90PMN-10PT ceramics) [4] and spinglasses (5% Au:Fe) [5] were studied with similar methods. The results have been interpreted as evidence for the existence of spatial heterogeneities.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Hole-Burning Experiments within Glassy Models with Infinite Range Interactions

Cugliandolo

Iguain

2000

Phys. Rev. Lett.

View full text Add to dashboard Cite

We reproduce the results of non-resonant spectral hole-burning experiments with fully-connected (equivalently infinite-dimensional) glassy models that are generalizations of the mode-coupling approach to nonequilibrium situations. We show that an ac-field modifies the integrated linear response and the correlation function in a way that depends on the amplitude and frequency of the pumping field. We study the effect of the waiting and recovery-times and the number of oscillations applied. This calculation will help descriminating which results can and which cannot be attributed to dynamic heterogeneities in real systems.PACS Numbers: 64.70.Pf, 75.10Nr One of the most interesting questions in glassy physics is whether localized spatial heterogenities are generated in supercooled liquids and glasses. [1] In most supercooled liquids, the linear response to small external perturbations is nonexponential in the time-difference τ . Within the "heteregeneous scenario", the stretching is due to the existence of dynamically distinguishable entities in the sample, each of them relaxing exponentially with its own characteristic time. A different interpretation is that the macroscopic response is intrinsically nonexponential. In the glass phase, the relaxation is nonstationary and the dependence in τ is also much slower than exponential.The heterogeneous regions, if they exist, are expected to be nanoscopic. The development of experimental techniques capable of giving evidence for the existence of such distinguishable spatial regions has been a challenge for experimentalists.With non-resonant spectral hole-burning (NSHB) techniques one expects to probe, selectively, the microscopic responses.[2] The method is based on a wait, pump, recovery and probe scheme depicted in Fig. 1. The amplitude of the ac perturbation is sufficiently large to pump energy in the sample, modifying the response as a linear function of the absorbed energy. The step-like perturbation δ is very weak and serves as a probe to measure the integrated linear response of the full system. The large ac and small dc fields can be magnetic, electric, or any other perturbation relevant for the sample studied. The idea behind the method is that the comparison of the modified (perturbed by the oscillation) and unmodified (unperturbed) integrated responses yield information about the microscopic structure of the sample. On the one hand, a spatially homogeneous sample will absorb energy uniformly and its modified integrated response is expected to be a simple translation towards shorter time-differences τ of the unmodified one. On the other hand, in a heterogeneous sample, the degrees of freedom that respond near the pump frequency Ω are expected to absorb an important amount of energy and a maximum difference in the relaxation (equivalently, a spectral hole) is expected to generate around t ∼ 1/Ω. The NSHB technique has been first applied to the study of supercooled liquids. The polarization response of dielectric samples, glycerol and propylene carbonate, was m...

show abstract

“…The procedure is analogous to hole burning studies (see, e.g., ref. 16) and ' classical ' fluorescence recovery after photo-bleaching (FRAP; see, e.g., ref. 17), but in real space.…”

mentioning

confidence: 99%

Real-space fluorescence recovery after photo-bleaching of concentrated suspensions of hard colloidal spheres

Simeonova

Kegel

2002

Faraday Disc.

View full text Add to dashboard Cite

In concentrated suspensions of fluorescent colloidal hard spheres (close to and above the glass transition density), we bleached part of the system in cube shaped regions using high intensity laser light. Recovery of these bleached cubes was followed in real space using confocal scanning laser microscopy (CSLM). This method provides mean squared particle displacements up to timescales that are three orders of magnitude beyond those available by present experimental techniques. We show that, above the (hard sphere) glass transition density, particles move over distances of the order of their own diameter on timescales of 10 6 to 10 8 Brownian times. Moreover, the mean squared displacement, hx 2 i, shows powerlaw behavior over seven time (t) decades: hx 2 i / t (0.30AE0.05) . This behavior is different from earlier observations by dynamic light scattering. It is argued that these differences are caused by gravity effects, as the only difference between the systems is the buoyant mass of the colloids.

show abstract

Long-Lived Dynamic Heterogeneity in a Relaxor Ferroelectric

Cited by 44 publications

References 21 publications

Effect of defect-induced internal field on the aging of relaxors

Effect of defect-induced internal field on the aging of relaxors

Hole-Burning Experiments within Glassy Models with Infinite Range Interactions

Real-space fluorescence recovery after photo-bleaching of concentrated suspensions of hard colloidal spheres

Contact Info

Product

Resources

About