Results 181 to 190 of about 2,040 (221)

Synthesis and characterization of multilayered ZnO/glass/ZnO varistors

AIP Conference Proceedings, 2020
Low-voltage surge filters are technologically important for the protection of modern computing and telecommunication systems operating at low voltages. In this context the design and characterization of varistors operating at low voltages constitutes a continuous challenge.
Varsamis, C. P. E., Valvi, C., Makris, N., Kamitsos, Efstratios I.   +3 more
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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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Varistor-capacitor characteristics of ZnO ceramics

Journal of Materials Science, 1986
Electrical 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, A. M. R. Senos, J. L. Baptista   +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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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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Different degradation processes in ZnO varistors

Ceramics International, 1996
Degradation of ZnO-based varistors has been attributed to ion migration in the depletion layers at intergrains. Experiments can then be explained as the result of the deformation of Schottky barriers present in the grain boundaries. However, the simple lowering of the barriers is not consistent with the observed results. We found that ion migration can
M.S. Castro, C.M. Aldao
openaire   +1 more source

Preparation of ZnO-glass varistor from tetrapod ZnO nanopowders

Materials Science and Engineering: B, 2002
Abstract Varistors based on ZnO–lead zinc borosilicate glass were prepared from tetrapod ZnO nanopowders, every one of which had four needle-like legs and each one was about 20 nm or less in diameter and from several hundreds of nanometers to several micrometers in length by the method of direct co-sintering synthesis of oxides instead of adding ...
Wu Jun, Xie Changsheng, Bai Zikui, Zhu Bailin, Huang Kaijin, Wu Run   +5 more
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ZnO varistors for liquid crystal displays

Journal of Applied Physics, 1982
ZnO varistors are excellent materials for multiplexing dichroic liquid crystal displays. We describe here the development of varistor materials tailored for this application. The varistors are large (∼25 cm diameter), uniform, and have relatively low dielectric constant.
Lionel M. Levinson, Donald E. Castleberry, Charles A. Becker   +2 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
openaire   +1 more source