Results 161 to 170 of about 2,040 (221)

Degradation phenomena of ZnO varistors

Physica Status Solidi (a), 1981
The dc degradation behaviour of ZnO varistors as a function of the variables current, temperature, and time is investigated. The degradation rate is phenomenologically presented by an equation reflecting the observed aging behaviour in dependence on the influencing variables.
W. Moldenhauer   +4 more
openaire   +1 more source

Microchemistry of ZnO Varistors

Proceedings, annual meeting, Electron Microscopy Society of America, 1992
ZnO varistors are made by mixing semiconducting ZnO powder with powders of other metal oxides e.g. Bi2O3, Sb2O3, CoO, MnO2, NiO, Cr2O3, SiO2 etc., followed by conventional pressing and sintering. The non-linear I-V characteristics of ZnO varistors result from the unique properties that the grain boundaries acquire as a result of dopant distribution ...
K. K. Soni   +4 more
openaire   +1 more source

Origin of ZnO Varistor

Journal of the American Ceramic Society, 1987
The varistor properties were examined in porous ZnO. The sample used contained no dopants such as Bi 2 O 3 or Pr 6 O 11 , which are usually considered to be useful in ...
Satoru Fujitsu   +2 more
openaire   +1 more source

Degradation in ZnO varistors

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
openaire   +1 more source

Thermal breakdown in ZnO-varistor ceramics

Physica Status Solidi (a), 1980
Thermal 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
openaire   +1 more source

Failure modelling for ZnO varistors

Journal of Materials Processing Technology, 1998
Abstract The energy-absorption capability of zinc oxide varistors depends on both the binder burn-out and shrinkage rate of the disc. This paper presents a study of the development of a failure model of a varistor disc with a nominal voltage V nom =5 kV and a diameter of 42 mm manufactured by rate-controlled sintering.
M.D Huda   +3 more
openaire   +1 more source

ZnO Varistors for Transient Protection

IEEE Transactions on Parts, Hybrids, and Packaging, 1977
ZnO varistors are novel ceramic semiconductor devices used for protection of electronic equipment against transient overvoltages due to switching surges or lightning. This article describes the microstructure, circuit behavior, and operation of ZnO varistors.
L. Levinson, H. Philipp
openaire   +1 more source

Conduction mechanisms in ZnO varistors

Journal of Applied Physics, 1980
The 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
openaire   +1 more source

Photoconduction of ZnO-Bi2O3 varistors

Journal of Materials Science Letters, 1989
Zinc 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
openaire   +1 more source

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