Structural, nonlinear electrical characteristics, and stability against DC-accelerated aging stress behavior of Er-doped 20 nm ZnO-Bi2 O3 -Mn2 O3 -based varistors.

Abstract

In this research, ZnO-Bi2 O3 -Mn2 O3 varistors manufactured from 20 nm ZnO powder and doped with different amounts of Er2 O3 were fabricated via the conventional ceramic processing method. The effect of various Er2 O3 concentrations (0.5-2.0mol%) on the sintered density, structural improvement, and nonlinear behavior of the 20 nm ZnO-Bi2 O3 -Mn2 O3 varistors was discussed. Different Er2 O3 concentrations exerted considerable influence on the varistors. The addition of large amounts of Er2 O3 led to the inhibition of grain growth by increasing the amount of the Er2 O3 -rich spinel phase. X-ray diffraction analysis showed that the addition of Er2 O3 to the varistor systems led to the development of Er2 O3 -rich phases during sintering. During sintering, the considerable surface area of the nanoparticle powder resulted in numerous interactions in the surfaces of the ceramics manufactured from 20 nm ZnO powder. The electrical behaviors of the varistors were substantially influenced by Er2 O3 . E1 mA evidently increased from 2,144.7 to 5,482.2V/mm with the increment in doping amount. The nonlinear coefficient also dramatically increased with the increase in Er2 O3 content. The ZnO nanoparticle-Bi2 O3 -Mn2 O3 varistors doped with 1.0-2.0mol% Er2 O3 possessed high voltage and nonlinearity and were stable against DC-accelerated aging stress.