Microstructure and electrical properties of vanadium-doped zinc oxide-based non-ohmic resistors

The microstructure and non-ohmic properties of the ternary system ZVM were investigated in accordance with Mn3O4 content. For all samples, the microstructure of the ternary system ZnO–V 2O5–Mn3O4 consisted of mainly ZnO grain and secondary phase Zn3(V O4)2. The incorporation of Mn3O4 to the binary system ZnO–V 2O5 was found to restrict the abnormal grain growth of ZnO. The breakdown voltage in the VV–II characteristics increased from 17.5 to 463.5 V/mm with the increase in Mn3O4 content. The incorporation of Mn3O4 up to 0.5 mol% improved non-ohmic properties by increasing non-ohmic coefficient, whereas the further additions decreased it. The highest non-ohmic coefficient (22.2) was obtained from Mn3O4 content of 0.5 mol%. It was found that the highest barrier height at grain boundary was 2.66 eV for Mn3O4 content of 0.5 mol%.