Abstract
It is shown that an addition of Sb2O5 or Nb2O5 (0.05–0.15 mol%) to the system SnO2–CoO–Cr2O3–Bi2O3 leads to the enhancement of grain growth. This effect is associated with the presence of the liquid Bi-phase in ceramics during sintering. The obtained ceramics possess non-linear current-voltage characteristics and can be used for preparing low voltage varistors. The non-linearity coefficient α reaches 22 and the characteristic electric field 692 V/cm for Nb-doped materials and 11 and 421 V/cm respectively for Sb-doped ceramics materials. The results of dc and ac electrical measurements, as well as scanning electron microscopy are presented and discussed in terms of the known barrier model for varistors.
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