ELECTRICAL-CONDUCTIVITY OF THE SOLID-SOLUTIONS XCEO(2)+(1-X)DY2O3 0.01-LESS-THAN-OR-EQUAL-TO-X-LESS-THAN-OR-EQUAL-TO-0.10

CeO2-doped Dy2O3 systems containing 1, 4, 7 and 10 mol.% CeO2 were found to be solid solutions by X-ray diffraction techniques. The lattice parameter a was obtained by the Nelson-Riley method, and its value increased with increasing dopant content. The average residual factors (R) obtained from X-ray intensity analysis based on oxygen interstitial and vacancy models were found to be 0.0631 and 0.1085, respectively, suggesting the oxygen interstitial model. The ratios of measured to calculated densities were found to be greater than 0.96, justifying the oxygen interstitial model. The results of thermal analysis showed that no phase transition occurred in the temperature range 500-1100 degrees C. The electrical conductivity was measured as a function of temperature from 500 to 1100 degrees C and of oxygen partial pressure from 5x10(-5) to 2x10(-1) atm. The exponential dependence of the electrical conductivity (sigma) on the oxygen partial pressure (P-O2) gives sigma alpha P-O2(1/n) with n=6, the main defect and charge carriers being the oxygen interstitial and the electron hole, respectively.