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|Título:||Electrical properties of SnO2 ceramic varistors withstanding high current pulses|
|Palabras clave:||Grain boundary|
|Fecha de publicación:||31-Jul-2012|
|Editorial:||Superficies y vacío|
|Descripción:||Electrical properties of new dense SnO2-CoO-Nb2O5-Cr2O3-Y2O3 varistor ceramics are studied. Current-voltage characteristics in the wide range from 10-11 to about 3.3·10³ A·cm-2 contain three regions. At low currents linear (Ohmic) region is found. Highly nonlinear region with the nonlinearity coefficient of about 50 at 1 mA·cm-2 is observed between 10-6 and 1 A·cm-2. At higher currents the upturn region is revealed. In this region the slope of current-voltage characteristic in the double logarithmic scale is decreased. The increase in dc current on time at fixed voltage and the hysteresis in the ac current-voltage characteristic are observed. These features can be related to Joule heating or electronic processes. However, after the high-current pulses only minor changes at low current are found. This indicates that studied ceramics withstand high-current overloads. This fact can be attributed to the formation of quite identical electrically-active grain boundaries throughout a sample. The grain resistivities <img border=0 src="../../../../../img/revistas/sv/v24n2/a5s1.jpg">estimated from high-current pulse data are the lowest known up to now for SnO2 varistors.|
|Aparece en las Colecciones:||Superficies y Vacío|
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