Publication

Relaxors as Superparaelectrics with Distributions of the Local Transition-Temperature

Alexander Tagantsev
1995
Journal paper

Abstract

A model of relaxors as superparaelectrics with a distribution of the local transition temperature has been investigated. The necessary model parameters are obtained from the analysis of the static polarization response of lead magnesium niobate and then employed in simulations of the frequency-dependent dielectric properties. The present model is compared with a previously published model of relaxors, based on a single transition temperature but with a distribution of the size of the polar regions. Both of them describe some characteristic features of relaxors, i.e. the shift of the peaks in temperature dependence of the real and imaginary parts of the dielectric permittivity with frequency and the broadening of the relaxation time spectrum on cooling. However, a model which takes into account the distribution of the size of the polar regions describes qualitatively correctly the shape of the relaxation time spectrum.

Official source

https://infoscience.epfl.ch/record/88826?ln=en

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Ontological neighbourhood

Electrical engineering

Electronic engineering: Analogue electronics

Related concepts (27)

The relative permittivity (in older texts, dielectric constant) is the permittivity of a material expressed as a ratio with the electric permittivity of a vacuum. A dielectric is an insulating material, and the dielectric constant of an insulator measures the ability of the insulator to store electric energy in an electrical field. Permittivity is a material's property that affects the Coulomb force between two point charges in the material. Relative permittivity is the factor by which the electric field between the charges is decreased relative to vacuum.

In electromagnetism, the absolute permittivity, often simply called permittivity and denoted by the Greek letter ε (epsilon), is a measure of the electric polarizability of a dielectric. A material with high permittivity polarizes more in response to an applied electric field than a material with low permittivity, thereby storing more energy in the material. In electrostatics, the permittivity plays an important role in determining the capacitance of a capacitor.

In electromagnetism, a dielectric (or dielectric medium) is an electrical insulator that can be polarised by an applied electric field. When a dielectric material is placed in an electric field, electric charges do not flow through the material as they do in an electrical conductor, because they have no loosely bound, or free, electrons that may drift through the material, but instead they shift, only slightly, from their average equilibrium positions, causing dielectric polarisation.

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