Results 171 to 180 of about 122,447 (215)
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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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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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Defects and degradation in ZnO varistor
Applied Physics Letters, 1996A systematic study of the defects in ZnO has been performed. The two commonly observed levels (L1, L2), located at around 0.15 and 0.24 eV under the conduction band, have been identified as native defects. The deep level transient spectroscopy depth profiling technique is applied on multilayer-chip-type ZnO varistors to determine the distribution ...
Wei-I Lee, Ruey-Ling Young
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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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Evaluation of ZnO Varistors by Photoacoustic Spectroscopy
Japanese Journal of Applied Physics, 2001ZnO varistors degraded under various conditions were evaluated by photoacoustic spectroscopy (PAS). The degradation where the grain boundary is damaged by DC bias stress is more than that by AC bias stress. PAS, however, reveals that the interior of the grains of the sample degraded by AC bias stress is much more damaged than that by the DC bias ...
Yasuhiro Ohbuchi Yasuhiro Ohbuchi +4 more
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Varistor-capacitor characteristics of ZnO ceramics
Journal of Materials Science, 1986Electrical properties of ZnO ceramics quenched from several temperatures during the cooling down from sintering temperature were correlated with microstructural changes. Barrier parameters were determined and their variation was interpreted under the assumption that measured donor densities were due to extrinsic donor defects segregated at grain ...
P. Q. Mantas +2 more
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Rate-controlled shrinkage of ZnO varistors
Journal of Materials Processing Technology, 1996Abstract Shrinkage of ZnO varistors has been controlled during the firing process at a constant rate using a feed back loop to control the heating rate. This was accomplished by developing software which calculates the shrinkage from a signal coming from a displacement transducer, then it compares the current shrinkage rate with a previously set ...
A. Al-Tounsi, R. Puyané, M.S.J. Hashmi
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Impedance and Modulus Spectroscopy of ZnO Varistors
Journal of Electroceramics, 1997The ac response of ZnO varistors has been investigated over thetemperature range 100 to 380°C using impedance and modulusspectroscopy. Impedance spectra show only a single peak, which representsthe most resistive component in the sample and is responsible for the dcproperties, whereas an additional peak appears in the modulus spectrum.
A.R. West, M. Andres-Verges
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Cooling rate effects in ZnO varistors
Journal of Materials Science: Materials in Electronics, 1992Cooling rate effects on ZnO-Bi2O3 varistors are presented. In particular, the oxygen vacancies (V o + ) concentration was determined by electron paramagnetic resonance (EPR) spectroscopy and related to the conductivity. It was found that a higher cooling rate provokes an increase of the V
M. S. Castro +2 more
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