Electrical behaviour of thin ZrO2 films containing some ceramic oxides

Zirconia was stabilized with MgO, CeO2 and Gd2O3 by a reactive thermal coevaporation process using an electron gun. Electrical measurements were performed in the frequency range 10 KHz to 10 MHz and for various temperatures ranging from 27-600 degrees C. For the ZrO2-MgO system, the dielectric constant epsilon and the a.c. electrical conductivity sigma were found to increase up to maximum values for the sample containing 15 mol.% MgO, then decrease for MgO content in the alloy higher than 15 mol.%. The ZrO2-CeO2 was found to be partially stabilized in a cubic lattice. The dielectric constant epsilon and sigma increased linearly with the CeO2 content in the range of concentration studied (8-36 mol.%). For the ZrO2-Gd2O3 System sigma and epsilon were optimized for the 8 mol.% Gd2O3 sample. The three systems investigated displayed a conduction process thermally activated and controlled by the hopping of charge carriers over the barrier separating two localized sites (Correlated Barrier Hopping).