The effect of humidity on the voltage–current characteristic of SnO2 based ceramic varistor

Tin dioxide based ceramics in the SnO2–Bi2O3–Co3O4–Nb2O5–Cr2O3 system exhibit highly non-linear voltage–current characteristics (non-linearity coefficient reaches 55–60 in electric fields of about 3500 V cm−1) in parallel with high humidity sensitivity in low electric fields (humidity sensitivity coefficient reaches 105). Such ceramics can be used for the fabrication of a device with combined varistor and humidity sensor properties. Voltage–current characteristics of ceramics with different amounts of bismuth oxide are studied in air with different relative humidity contents.