La Doped Layered Structure Low-Voltage ZnO Varistor

Abstract:

A novel fabricated technique, by feeding two sets of different ZnO formulations powder in a die by parts, molded only once to produce layered structure(including layer A and layer B) low-voltage ZnO varistor. The samples are examined by using energy dispersive X-ray spectroscopy (EDS), electron probe microanalysis (EPMA), scanning electron microscope (SEM) and DC electrical measurements. EDS and EPMA data indicate that doped elements only exists in layer A, The results of SEM indicate that secondary phases are formed at grain boundaries in layer A, not found in layer B. It is found that the electrical properties of low-voltage varistor are improved without reducing thickness and changing energy absorption capabilities. The higher nonlinearity coefficients, lower breakdown fields and leakage currents of layered structure low-voltage ZnO varistor, as compared to those of ZnO varistor fabricated from the conventional route. The improved current-voltage properties are attributed to the band structure difference in both sides grains, due to the different ion concentration and species in both sides of grain boundary. Layered structure varistor also has more simpler prepared technology than multilayer chip varistor.

• Periodical: Key Engineering Materials (Volumes 512-515)
• Pages: 1263-1267
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.512-515.1263
• Online since: June 2012
• Authors: Xing Gao, Guo You Gan, Li Hui Wang, Ji Kang Yan, Jian Hong Yi, Jing Hong Du, Jia Min Zhang
• Keywords: Electrical Properties, Layered Structure, Low-Voltage, ZnO Varistor

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