Effect of electrode material on sealing wax thermo-electret charge

Thermo-electrets of sealing wax have been prepared using different metal electrodes: tin, aluminium, nickel, copper, lead and zinc (Series A) and pairs of metallic — tin and non-metallicmica (Series B) keeping other preparative parameters to be the same in each series. Surface charge has been measured on anode side of each thermo-electret. Surface charge characteristics have been discussed in the light of the results obtained in earlier studies on sealing wax thermo-electrets by the authors and existing views on the origin of charges. These results suggest that origin of homocharge in thermo-electrets is due to injection of charge carriers supplied by the electrodes into the dielectric surface and freezing in near the surface and getting trapped in the surface levels. The origin of heterocharge is due to inhomogeneous distribution of charge carriers originating in the bulk on account of their trapping.