K. Guergouri
University Larbi Ben M'Hidi of Oum El Bouaghi, Algeria
Title: Investigation of structural and electrical properties of manganese doped ZnO varistors prepared from nanopowders
Biography
Biography: K. Guergouri
Abstract
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. The XRD spectra indicate that pure and Mn doped ZnO powders are solid solution, with an average grain size varying between 36.15 nm to 65.92 nm. The grain size decreases with the increase of Mn concentration except for 5 mol % Mn, where there is an unexpected increase. This is confirmed by MET images. The current-voltage J(E) characteristics show that the breakdown electric field increases with increasing Mn concentration ranging from 315.62V/cm to 733.33V/cm except for the Zn-5%Mn-O varistor, where the non linear coefficient α and breakdown electric field are lower. In general the more the grain size decreases the more the varistor effect and the threshold voltage increase.