Grain and grain boundary conduction in zinc oxide varistors before and after DC degradation

Asokan, T.; Freer, Robert

doi:10.1016/0955-2219(93)90114-7

Cited by 13 publications

(10 citation statements)

References 15 publications

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“…Some investigations have been performed with the aim of establishing the role of grain and grain boundary regions in mediating the nonohmic properties. Asokan and Freer 10 investigated the behavior of the grain and grain boundary regions using the impedance spectrum in a ZnO–Bi 2 O 3 ‐based varistor, and discussed the observed variation in the activation energies of grain and grain boundary regions. Bartkowiak et al 11 .…”

Section: Introductionmentioning

confidence: 99%

Sintering Temperature Dependence of Grain Boundary Resistivity in a Rare‐Earth‐Doped ZnO Varistor

Cai

Lin

et al. 2006

Journal of the American Ceramic Society

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We present a rare‐earth‐doped ZnO ceramic with nonohmic electrical properties. Analysis of the microstructure and composition indicates that the ceramic is composed of the main phase of ZnO and the second phase of rare‐earth oxides (e.g., Dy2O3, Pr6O11, Pr2O3). The average grain size is markedly increased from 3 to 18 μm, with an increase in the sintering temperature from 1150° to 1350°C. The corresponding varistor voltage and nonlinear coefficient decrease from 1014 to 578 V/mm, and from 15.8 to 6.8, respectively. The resistivity of grain and grain boundary evaluated by the complex impedance spectrum indicates that the resistivity of the grain is approximately constant (∼103Ω), and the resistivity of the grain boundary decreases. The relative dielectric permittivity of the sintered ceramic samples is much larger than that of pure ZnO ceramic, which should be ascribed to the internal boundary layer capacitance effect.

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Section: Introductionmentioning

confidence: 99%

Sintering Temperature Dependence of Grain Boundary Resistivity in a Rare‐Earth‐Doped ZnO Varistor

Cai

Lin

et al. 2006

Journal of the American Ceramic Society

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“…It consists of using the same signal Vϭ⌬VϵV 0 e it , both to bias the sample and to measure its capacitance. The frequency is 50-60 Hz, which is easy to apply, lies far away from any reported relaxation, 23,28 and satisfies Eq. ͑17͒ ͑with typical values of barrier height 4 ⌽ B (0) Ϸ0.6 eV and GB states capture cross section 1,4 Ϸ5ϫ10 Ϫ14 cm 2 ͒.…”

Section: New Characterization Methods For Sbp-polycrystalline Matermentioning

confidence: 99%

Mott–Schottky behavior of strongly pinned double Schottky barriers and characterization of ceramic varistors

Fernández-Hevia

Frutos

Caballero

et al. 2002

Journal of Applied Physics

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Nature of the Schottky-type barrier of highly dense SnO 2 systems displaying nonohmic behaviorThis work studies the capacitive behavior of an intergranular double Schottky barrier, which describes nonlinear charge transport in polycrystalline semiconductors. It is found that: ͑i͒ a widely applied version of the Mott-Schottky equation can be inadequate, and can lead to significant errors; ͑ii͒ a property called strong barrier pinning ͑SBP͒, underlies most attempts to obtain physical parameters from C -V measurements; and ͑iii͒ under SBP, known results from one-sided Schottky barriers can be used to analyze C -V response, showing that correct physical parameters are obtained at low frequency and that high frequency measurements are not advantageous. A new characterization method is introduced, which allows high voltage devices to be directly measured, and yields comparative information about average donor density and barrier height. Besides its technological applicability, the method simplifies the study of scale effects. Experimental results support the theoretical considerations and the proposed characterization method. The usefulness of the method is illustrated by studying the effects of current-pulse degradation on the physical parameters of high voltage varistors.

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“…[10][11][12] Recently, we prepared TiO 2 -rich CaCu 3 Ti 4 O 12 ͑TCCTO͒ ceramics by a solid-state sintering process and observed large nonlinear electrical and high dielectric behaviors. Grain boundary structures are usually produced by some interaction between neighboring bulk grains or some other additives.…”

Section: Grain Boundary Behavior In Varistor-capacitor Tio 2 -Rich Camentioning

confidence: 99%

Grain boundary behavior in varistor-capacitor TiO2-rich CaCu3Ti4O12 ceramics

Lin

Cai

et al. 2008

Journal of Applied Physics

107

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We prepared TiO 2 -rich CaCu 3 Ti 4 O 12 ͑CCTO͒ ceramics by a solid-state sintering process and observed large nonlinear electrical and high dielectric behaviors. Microstructure and phase composition analyses show that CCTO grain-amorphous/TiO 2 nanograin boundary-CCTO grain junction structures exist in these TiO 2 -rich CCTO ceramics, which leads to the nonlinear electrical and high dielectric properties. The temperature dependence of impedance spectroscopy and relationships between electrical current density versus applied electrical field indicate that the activation energy of the grain boundary for the TiO 2 -rich CCTO ceramics is almost the same as the potential barrier height and both of them are weakly independent of the doped concentration of TiO 2 , which supports the internal barrier layer capacitor model of Schottky barriers at the grain boundaries between semiconducting CCTO grains.

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Grain and grain boundary conduction in zinc oxide varistors before and after DC degradation

Cited by 13 publications

References 15 publications

Sintering Temperature Dependence of Grain Boundary Resistivity in a Rare‐Earth‐Doped ZnO Varistor

Sintering Temperature Dependence of Grain Boundary Resistivity in a Rare‐Earth‐Doped ZnO Varistor

Mott–Schottky behavior of strongly pinned double Schottky barriers and characterization of ceramic varistors

Grain boundary behavior in varistor-capacitor TiO2-rich CaCu3Ti4O12 ceramics

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