Results 141 to 150 of about 290 (180)

Metastable Barrier Voltage in ZnO Varistors

MRS Proceedings, 1981
ABSTRACTA reversible change in barrier voltage is observed in assintered ZnO varistors upon application and removal of the applied voltage. This is attributed to a metastable component in the grain boundary Schottky barriers. Varistors show improved stability when the metastable component is removed or fixed by heat treatment.
Tapan K. Gupta, William G. Carlson, Barbara O. Hall   +2 more
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Rate-controlled shrinkage of ZnO varistors

Journal of Materials Processing Technology, 1996
Abstract 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, 1997
The 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, 1992
Cooling 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, L. Perissinotti, C. M. Aldao   +2 more
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Intrinsic defects in ZnO varistors

Journal of Applied Physics, 1983
Theoretical calculations are presented for equilibrium concentrations of zinc and oxygen vacancies in ZnO. Results are presented at the sintering temperature, and also at room temperature. Theoretical calculations of reaction constants show that the intrinsic donor is the oxygen vacancy, rather than the zinc interstitial.
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High-field ZnO-based varistors

Journal of Physics D: Applied Physics, 1995
The 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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Advances in ZnO–Bi2O3 based varistors

Journal of Materials Science: Materials in Electronics, 2015
In 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, Shengtao Li, Pengfei Cheng, Mohammad A. Alim   +3 more
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Spinel Phases in ZnO Varistors

Physica Status Solidi (a), 1980
K.-H. Bäther, D. Hinz, N. Mattern, M. Bitterlich, W. Brückner   +4 more
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Grain junction properties of ZnO varistors

Applications of Surface Science, 1979
Abstract Grain-grain junctions in ZnO varistor ceramics were electrically contacted by conventional photoresist- and contact deposition techniques and investigated in terms of the statistical distribution of the breakdown voltage. Its maximum appears at 3.4 V for constant current of 5 μA.
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ZnO varistors with iron oxide

2020
ZnO VARI STORE WITH IRON OXIDE CAM, Ibrahim Faculty of Engineering Department of Metallurgical Engineering, M. S. Thesis Supervisor: Prof. Dr. Muharrem T1MUCÎN 114 pages, February 1989 ABSTRACT In the present work, addition of Fe2Û3 on the characteristics of ZnO-var istors were studied.
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