Electrical properties of
SnO2-Co3O4-Nb2O5-Cr2O3 ceramics
sintered at 1100−1400 °C were studied. Materials exhibit
known varistor properties (superlinear and symmetric current-voltage
characteristic) only if sintered at relatively high temperatures of
1300−1400 °C. In ceramics sintered at 1100−1200 °C,
the current limiting effect (current is saturated and even decreased
with voltage increase) and its transformation into the varistor
effect were found. It was ascertained that the capacitance of
samples is decreased with increasing frequency more sharply for
ceramics sintered at 1100−1200 °C than at
1300−1400 °C. The low-frequency capacitance and ac
conductance of ceramics sintered at 1100−1200 °C were
increased and showed further strong decrease with electric field.
The results of electrical measurements are discussed in terms of the
barrier model.