Major effects on electrical properties of ZnO–V2O5–MnO2–Nb2O5 ceramics with small Gd2O3 doping changes

This study focuses on that Gd2O3-modified ZnO–V2O5–MnO2–Nb2O5 ceramics were sintered at temperature as low as 900 °C and very good varistor properties. Increasing amount of Gd2O3 decreased the sintered density in the range of 5.51–5.44 g/cm3 and it reduced the average grain size from 5.6 to 5.2 μm up to 0.1 mol%. The breakdown field increased from 4822 to 5365 V/cm up to 0.05 mol% with an increase in the amount of Gd2O3, whereas a further increase caused it to decrease. The ceramics modified with 0.05 mol% in the amount of Gd2O3 exhibited an excellent nonlinear coefficient as high as 66. The donor concentration increased from 4.46 × 1017 to 7.38 × 1017 cm−3 with an increase in the amount of Gd2O3 and the barrier height exhibited a maximum value (1.22 eV) at 0.05 mol% Gd2O3.