Results 141 to 150 of about 290 (180)

Ceramic varistors based on ZnO–SnO2

Journal of the European Ceramic Society, 2004
Abstract Model ceramic varistor formulations based on 98% ZnO–SnO2 (plus 2% oxides of Bi, Co and Mn) were prepared by conventional powder processing routes; specimens were sintered at 1150–1275 °C. The product density increased with SnO2 content, but decreased with increase in sintering temperature.
A. Anastasiou, M.H.J. Lee, C. Leach, R. Freer   +3 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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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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Evaluation of ZnO Varistors by Photoacoustic Spectroscopy

Japanese Journal of Applied Physics, 2001
ZnO 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, Akitsugu Kimura Akitsugu Kimura, Toshio Kawahara Toshio Kawahara, Jun Morimoto Jun Morimoto, Taro Toyoda Taro Toyoda   +4 more
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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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Pulse response characteristics of ZnO varistors

Journal of Applied Physics, 1990
A study is reported of the influences of temperature, circuit resistance, and pulse repetition rate on the ZnO varistor inductive pulse response that is disclosed by voltage overshoot and current undershoot. Exponential time constants are fitted to the voltage overshoot and the current undershoot obtained by using high- and low-impedance pulse supplies,
F. A. Modine, R. B. Wheeler
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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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Photoluminescence study of ZnO varistor stability

Journal of Electronic Materials, 1995
Photoluminescence (PL) measurements were carried out on commercial ZnO varistor samples that were electrically stressed and/or annealed at different temperatures. Changes in the intensity of green and yellow luminescence centers were studied as a function of annealing treatment.
M. S. Ramanachalam, A. Rohatgi, W. B. Carter, J. P. Schaffer, T. K. Gupta   +4 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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