Results 111 to 120 of about 4,953 (161)
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Journal of Physics: Condensed Matter, 1993
Among the mechanisms suggested to account for degradation of varistor materials, ion migration has strong support. Mobile, positively charged ions in the depletion layer would be the key element in degradation. In this context, the authors discuss the consequences of an electrical stressing on the current-temperature characteristic of a comment ...
M S Castro, M A Benavente, C M Aldao
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Among the mechanisms suggested to account for degradation of varistor materials, ion migration has strong support. Mobile, positively charged ions in the depletion layer would be the key element in degradation. In this context, the authors discuss the consequences of an electrical stressing on the current-temperature characteristic of a comment ...
M S Castro, M A Benavente, C M Aldao
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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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Polarization currents in varistors
Journal of Applied Physics, 1990The time, voltage, and temperature dependencies of transient polarization currents are reported for two types of varistors (i.e., ZnO and a SiC composite). The current transients exhibit a power-law time response to a step change in voltage (i.e., I≊I0/tm, where m is slightly less than unity) that persists over a time scale exceeding 10−8–104 s.
F. A. Modine +4 more
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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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IEEE Electrical Insulation Magazine, 1989
An overview is given of zinc oxide varistors, which are made of semiconducting ceramics with highly nonohmic current-voltage characteristics, which originate at the grain boundaries. These varistors are widely utilized to protect electric power lines and electronic components against dangerous voltage surges.
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An overview is given of zinc oxide varistors, which are made of semiconducting ceramics with highly nonohmic current-voltage characteristics, which originate at the grain boundaries. These varistors are widely utilized to protect electric power lines and electronic components against dangerous voltage surges.
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Thermal breakdown in ZnO-varistor ceramics
Physica Status Solidi (a), 1980Thermal breakdowns representing an essential mechanism for the lifetime limitation of ZnO-varistor ceramics are characterized with respect to the parameters of the breakdown point (especially breakdown temperature Tb) (for 21 °C as ambient temperature: Tb = 174 °C).
W. Brückner, W . Moldenhauer, D. Hinz
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Varistor effect in semiconductor ferroelectrics
Technical Physics, 1997This paper treats the effect of an external field on the magnitude of potential barriers and the potential contour near a charged boundary between crystallites in polycrystalline ferroelectric semiconductors. It is shown that this effect depends on the mutual directions of the external field and the polarization in the ferroelectric bulk, and that the ...
A. N. Pavlov, I. P. Raevskii
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Hybrid Circuits, 1993
Various thick film varistor constructions were made and characterised: ‘sandwich’, ‘interdigitated’ and ‘segmented’ varistors. The varistor active layer thickness, the electrode surface value and shape were varied. The Ul characteristics of these varistors were compared mutually, and with the Ul characteristics of the smallest chip varistors.
O.S. Aleksić +3 more
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Various thick film varistor constructions were made and characterised: ‘sandwich’, ‘interdigitated’ and ‘segmented’ varistors. The varistor active layer thickness, the electrode surface value and shape were varied. The Ul characteristics of these varistors were compared mutually, and with the Ul characteristics of the smallest chip varistors.
O.S. Aleksić +3 more
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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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Varistor versus Environment: Winning the Rematch
IEEE Transactions on Power Delivery, 1986An unusual case of difficult application of surge protective devices was solved by field measurements with retrofit of protective devices suitable for the particular environment. Onsite measurements indicated that capacitor switching transients were causing excessive current surges in the varistors and fuses protecting the input to a thyristor motor ...
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