Modified citrate gel techniques to produce ZnO-based varistors (Part II - Electrical characterisation)

The electrical characteristics of doped ZnO pellets prepared by novel, modi fied citrate gel routes and the conventional mixed oxide route were compare d. The mixed oxide route produced rather inhomogeneous materials at the sin tering temperatures employed in this study (970 degreesC and 1000 degreesC) . In contrast, the modified citrate gel routes enabled some control over th e location of the minority components incorporated into the ZnO. By positio ning these components according to their function, varistor pellets with hi gher nonlinearity coefficients, higher characteristic voltages and slightly higher energy absorption abilities than those of the conventional mixed-ox ide route were prepared. Differences in the electrical characteristics of v aristors prepared by different routes but with apparently similar microstru ctures was taken to indicate successful control over the compositional homo geneity.