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Conduction mechanisms in ZnO varistors
Journal of Applied Physics, 1980The thermionic emission enhanced by barrier lowering and the Zener tunnelling in ZnO varistors are discussed. Capacitance versus voltage, reverse current versus temperature, and 1/f noise measurements have been performed on commercial varistors. A model is proposed from which follows a diffusion voltage VD which is consistent both with the 1/C2 vs V ...
L. K. J. Vanadamme, J. C. Brugman
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Photoconduction of ZnO-Bi2O3 varistors
Journal of Materials Science Letters, 1989Zinc oxide (ZnO) ceramics with a few mol % Bi203, CoO, MnO, Sb203, etc., as additives exhibit a high non-ohmic property in their voltage-current characteristics [1, 2], and therefore they are called varistors and are widely used for surge protection against transient voltage and powder overload [3].
T. Sekiya +3 more
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High-field ZnO-based varistors
Journal of Physics D: Applied Physics, 1995The role of principal additives is investigated in an attempt to obtain high-threshold-field ZnO-based varistors in the traditional way. In the order of effect level, these are Sb2O3, Co3O4, Cr2O3 and MnO2. In the range of 0.5-5 mol%, the increase of additive content decreases the average ZnO grain size.
A Bui, H T Nguyen, A Loubiere
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MRS Proceedings, 1981
The theory of ZnO varistors has evolved along with the increasingly detailed experimental description [1-2]. The extreme nonlinearity in the currentvoltage curves naturally led the early investigators to suggest the well-known nonlinear mechanisms, such as space-charge limited currents or electron tunneling. Later experiments made these first proposals
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The theory of ZnO varistors has evolved along with the increasingly detailed experimental description [1-2]. The extreme nonlinearity in the currentvoltage curves naturally led the early investigators to suggest the well-known nonlinear mechanisms, such as space-charge limited currents or electron tunneling. Later experiments made these first proposals
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Prebreakdown Conduction in ZnO Varistors
Journal of the American Ceramic Society, 1992A model which quantitatively accounts for the important features of prebreakdown conduction in ZnO‐based metal oxide varistors in presented. The prebreakdown current dependence with applied voltage and temperature enables us to extract several features for the grain boundary.
Miriam S. Castro +3 more
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Phase development in ZnO varistors
Advances in Applied Ceramics, 2014Based on a typical ZnO varistor composition (97·0 mol.-% ZnO, 1·0 mol.-% Bi2O3, 1·0 mol.-% Sb2O3, 0·5 mol.-% MnO and 0·5 mol.-% Co3O4), phase development of the ZnO varistor during sintering has been investigated using in situ high temperature X-ray diffraction up to 900°C, and conventional ambient X-ray diffraction for samples sintered at 900°C to ...
Fan, J, Poosimma, P, Freer, Robert
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Time Dependence of Degradation in ZnO Varistors
physica status solidi (a), 1982Starting from the results of a previous paper on the functional relationship of the degradation of ZnO-varistors and the influence factors (especially U, I,T) an equation system is derived to describe the time-dependence of the degradation. The solutions including the contribution of degradation-, recovery- and increasing effects of currents and ...
W. Brückner +2 more
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Bi2O3 vaporization from ZnO-based varistors
Journal of the European Ceramic Society, 2005Abstract Bi 2 O 3 -doped ZnO ceramic varistors are usually sintered at temperatures near to 1200 °C in the presence of a Bi-rich liquid phase, which is partially vaporized during the sintering process. Volatilization of bismuth oxide depends on the total surface area in direct contact to the reaction atmosphere and this in turn is related to the area/
M. Peiteado +4 more
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Advances in ZnO–Bi2O3 based varistors
Journal of Materials Science: Materials in Electronics, 2015In this review paper detailed development of the ZnO–Bi2O3 based polycrystalline varistors are presented as the technological importance emerged with the rapid applications of the gapless surge protectors superseding traditional gapped SiC designs. The excellent symmetric nonlinear current–voltage (I–V) characteristic of these varistors results from ...
Jianying Li +3 more
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Theory of conduction in ZnO varistors
Journal of Applied Physics, 1979A theory is presented which quantitatively accounts for the important features of conduction in ZnO-based metal-oxide varistors. This theory has no adjustable parameters. Using the known values of the ZnO band gap, donor concentration n0, and low-voltage varistor leakage-current activation energy, we predict a varistor breakdown voltage of ?3.2 V/grain
G. D. Mahan +2 more
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