Note on Theories of Time-Varying Space-Charge Polarization

Macdonald, J. Ross

doi:10.1063/1.1740744

Cited by 30 publications

(3 citation statements)

References 9 publications

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“…thermal activation) and the absence of any significant effects of (i) electrode materials and (ii) sample thickness makes tunnelling unlikely as a possible mechanism to explain the nature of absorption current (Wintle 1973) in polypropylene. The process of electrode polarization is also unlikely because of the absence of electrode effects and also because the observed 'fi' values (see $3.1) are significantly different from the theoretically predicted model (MacDonald 1955).…”

Section: I High-temperature Regionmentioning

confidence: 77%

A study of absorption currents in polypropylene

Gupta

Joyner

1976

J. Phys. D: Appl. Phys.

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Charging and discharging current transients in polypropylene films were measured over a wide range of temperatures and electric fields. Some limited studies of the behaviour of these current transients were also made with different electrode materials and sample thicknesses. The experimental evidence suggests that the absorption current in the temperature range 83-270K may be caused mainly by dipolar processes associated with structural motions. At temperatures above approximately 270K the absorption current may be attributed to a carrier hopping process.

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Section: I High-temperature Regionmentioning

confidence: 77%

A study of absorption currents in polypropylene

Gupta

Joyner

1976

J. Phys. D: Appl. Phys.

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“…The technique used for the measurement of dc specific conductance depended on the resistance of the crystal. For R> 10 formed the grid leak of the input stage of a stable dc amplifier. A null method was used, to measure the voltage drop across R g , standard voltages being derived from a Tinsley Vernier potentiometer.…”

Section: Methodsmentioning

confidence: 99%

Polarization Effects in the Ionic Conductivity of Alkali Halide Crystals. II. Current—Time Dependence

Allnatt

Jacobs

Maycock

1965

The Journal of Chemical Physics

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The dc polarization of KCl at high temperatures has been investigated for the first time. Current—time curves may be resolved as the sum of a steady-state current and the time-dependent polarization current: the latter may be represented as the sum of two exponential terms. The relaxation times for these two processes are of the order of 40 and 250 sec at around 850°K. The Jaffé (constant-field) theory has been extended to include the case of low fields and the resulting equations have been solved numerically. The calculated relaxation times are an order of magnitude larger than those found experimentally. The reason for this discrepancy is probably the severity of the constant-field approximation. The polarization is attributed to the slowness of the electrode processes compared to the velocity of the carriers in the bulk crystal and numerical values of the discharge parameter are derived. These are consistent with an activation energy for the electrode process of about 2 eV.

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“…Mobile charges are assumed to accumulate only at the boundaries between the various phases. This major limitation is, however, not easily overcome, for when space-charge effects become dominant the law of superposition of potential is no longer applicable and solutions cannot be obtained in close form (Macdonald, 1955). The important conclusion to be drawn from this study is, then, that since the linear electrical parameters are not capable of explaining the observed force on the particle, this force must have its primary origin in an interaction between the non-uniform electric field and induced ionic space-charge which presumably is created in the particle's interlayer regions and in the loosely associated external surface layer.…”

Section: Validity Test Of Derived Equationsmentioning

confidence: 99%

Dielectrophoretic Behavior of Clay Minerals I. Dielectrophoretic Separation of Clay Mixtures

McEuen

1963

Clays clay miner. (Natl. Conf. Clays Clay Miner.)

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This paper describes a method and apparatus for separating clay particles according to their ability to store electrical energy. Separation is accomplished by opposing an electrical dielectrophoretic force by a mechanical centrifugal force. The apparatus used to create these forces consists of an axially rotating, fluid-filled cylinder in which a non-uniform electric field is maintained by means of radially disposed electrode vanes. The behavior in this separator of illite, prochlorite, montmorillonite, halloysite, and kaolinite is reported. Observed differences in the dielectrophoretic force acting on these clays indicate that they can be separated one from another by this method. The basic equations which govern the motion of particles in this separator are discussed. From these equations and known electrical properties of clays it is concluded that the large dielectrophoretic force which acts on a clay particle must have its primary origin in an interaction between the non-uniform electric field and induced ionic spacecharge which presumably is created in the particle's interlayer regions and in the loosely associated external surface layer.

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Note on Theories of Time-Varying Space-Charge Polarization

Abstract: Articles you may be interested inTheory of space-charge polarization for determining ionic constants of electrolytic solutions

Cited by 30 publications

References 9 publications

A study of absorption currents in polypropylene

A study of absorption currents in polypropylene

Polarization Effects in the Ionic Conductivity of Alkali Halide Crystals. II. Current—Time Dependence

Dielectrophoretic Behavior of Clay Minerals I. Dielectrophoretic Separation of Clay Mixtures

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