ISSN:
1013-9826
Source:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
The relationship between the crystal structure of Bi2O3 and the recovery of the electricaldegradation of ZnO varistors was investigated. The evaluation methods used were analysis of thevoltage-current (V-I) characteristics, scanning electron microscopy (SEM), energy-dispersion X-rayspectroscopy (EDX), and X-ray diffraction (XRD) measurements. The electrical degradation wasestimated by the nonlinearity of the V-I characteristics. A marked recovery of the nonlinearity of theV-I characteristics was observed for a sample having the crystal structure of δ-type Bi2O3. It isspeculated that the electrical degradation is markedly recovered for optimum conditions of both theamount and the crystal structure of the added Bi2O3, because, for samples sintered for a long time,the recovery speed is shorter than that for samples sintered for a shorter time. During long-timesintering, the amount of Bi2O3 decreased because of evaporation. No change of the crystal structureof Bi2O3 was observed upon repeated the electrical degradation and the recovery. It is suggested thatanother mechanism apart from the diffusion of oxygen ions through the grain boundaries of ZnOparticles contributes to the electrical degradation and recovery of the nonlinearity of V-Icharacteristics
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/01/55/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.350.209.pdf
Permalink