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

CeO2-doped Dy2O3 systems containing 1, 4, 7 and 10 mol.% CeO2 were fou nd to be solid solutions by X-ray diffraction techniques. The lattice parameter a was obtained by the Nelson-Riley method, and its value inc reased 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, s uggesting the oxygen interstitial model. The ratios of measured to cal culated densities were found to be greater than 0.96, justifying the o xygen 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 temperat ure from 500 to 1100 degrees C and of oxygen partial pressure from 5x1 0(-5) to 2x10(-1) atm. The exponential dependence of the electrical co nductivity (sigma) on the oxygen partial pressure (P-O2) gives sigma a lpha P-O2(1/n) with n=6, the main defect and charge carriers being the oxygen interstitial and the electron hole, respectively.