5TH International Congress on Technology - Engineering & Science - Kuala Lumpur - Malaysia (2018-02-01)

Investigation Of Structural And Electrical Properties Of Manganese Doped Zno Varistors Prepared From Nanopowders

Non-ohmic properties of pure and doped zinc oxide varistors are widely used to manufacture good devices. These varistors are generally used in electrical or electronic circuits to protect them from voltage surges. In this study; pure and Mn doped ZnO nanopowders have been synthesized by a soft chemistry method, the sol-gel route. The obtained powders after calcination at 500°C are consolidated and sintered using conventional furnace at 1075°C for 15 min. The obtained pellets are characterized by: X-ray diffraction, MET, UV-Visible and electrical measurement. The XRD spectra indicate that pure and Mn doped ZnO powders are solid solution, with average grain sizes varying between 36.15 nm to 65.92 nm .The grain size decreases with increasing Mn concentration and reaches its highest value at 5 mol% Mn, which confirmed by MET images. On the other hand UV-Visible spectra indicate that the optical gap value decreases from pure ZnO to reach an average value for Mn doped ZnO. The current-voltage I(V) characteristics show that the breakdown electric field increases with increasing Mn concentration ranging from 315.62V/mm to 733.33V/mm except for the Zn-5%Mn-O varistor, where the non linear and breakdown electric field are lower. In general the smaller the grain size, the more the varistor effect and the threshold voltage increase.
Amal Boumezoued, Kamel Guergouri, Djamil Rechem, Mourad Zaabat, Regis Barille