Non-ohmic conduction in tin dioxide based ceramics with copper addition

Gaponov, A. V.; Glot, A. B.

The current-voltage characteristics and temperature dependences of electrical conductivity in SnO2-Co3O4-Nb2O5-Cr2O3-CuO semiconductor ceramics are studied, and possible mechanism of non-ohmic conduction in these materials is discussed. Due to addition of CuO up to 0,5 mol. %, the nonlinearity coefficient is increased up to 75, and the electric field is decreased down to 3900 <$E roman {V~cdot~ cm sup -1}> (at <$E 1~roman mA~cdot~ roman cm sup -2>). It makes CuO addition useful for the preparation of SnO2-based varistors. It is concluded that the electrical conduction is controlled by grain-boundary barriers. The activation energy of electrical conduction <$E E sub sigma> (the barrier height <$E phi>) is decreased with an increase in the electric field E. The higher slope of the <$E E sub sigma (E)> dependence at high fields can be related to a participation of minority carriers (holes). The addition of more than 0,5 mol. % CuO leads to degradation of the varistor effect due to percolation via quite conductive CuO-based intergranular phase.


	Наукова періодика України		Semiconductor physics, quantum electronics & optoelectronics