Results 171 to 180 of about 2,258 (200)
Some of the next articles are maybe not open access.
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
openaire +2 more sources
Time Dependence of Degradation in ZnO Varistors
physica status solidi (a), 1982Starting from the results of a previous paper on the functional relationship of the degradation of ZnO-varistors and the influence factors (especially U, I,T) an equation system is derived to describe the time-dependence of the degradation. The solutions including the contribution of degradation-, recovery- and increasing effects of currents and ...
W. Brückner +2 more
openaire +1 more source
Bi2O3 vaporization from ZnO-based varistors
Journal of the European Ceramic Society, 2005Abstract Bi 2 O 3 -doped ZnO ceramic varistors are usually sintered at temperatures near to 1200 °C in the presence of a Bi-rich liquid phase, which is partially vaporized during the sintering process. Volatilization of bismuth oxide depends on the total surface area in direct contact to the reaction atmosphere and this in turn is related to the area/
M. Peiteado +4 more
openaire +1 more source
Advances in ZnO–Bi2O3 based varistors
Journal of Materials Science: Materials in Electronics, 2015In 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 +3 more
openaire +1 more source
Theory of conduction in ZnO varistors
Journal of Applied Physics, 1979A theory is presented which quantitatively accounts for the important features of conduction in ZnO-based metal-oxide varistors. This theory has no adjustable parameters. Using the known values of the ZnO band gap, donor concentration n0, and low-voltage varistor leakage-current activation energy, we predict a varistor breakdown voltage of ?3.2 V/grain
G. D. Mahan +2 more
openaire +1 more source
Pulse response characteristics of ZnO varistors
Journal of Applied Physics, 1990A 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
openaire +1 more source
A barrier model for ZnO varistors
Journal of Applied Physics, 1979A model of current transport in ZnO varistors is proposed. The model is a modification of an earlier one suggested by Levine, with the major difference being the inclusion of a thin (?10 Å) ’’disordered’’ layer which separates the single-crystal ZnO grains.
P. L. Hower, T. K. Gupta
openaire +1 more source
Synthesis and characterization of multilayered ZnO/glass/ZnO varistors
AIP Conference Proceedings, 2020Low-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. +3 more
openaire +2 more sources
Metastable Barrier Voltage in ZnO Varistors
MRS Proceedings, 1981ABSTRACTA 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 +2 more
openaire +1 more source
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
openaire +1 more source