Résumé
The preparation of Th 1-x Y x O 2-x/2 ceramics, to be used as electrolyte in oxygen sensors for sodium-cooled nuclear reactors, was successfully undertaken from oxalate precursors. Such method was found to provide quantitative precipitation of the cations into (Th,Y)(C 2 O 4) 2 $2H 2 O solid solutions up to x ¼ 0.15 while a polyphase system was obtained for x ¼ 0.22. The corresponding oxides were obtained through heat treatment in air at 500 C and characterized by the means of PXRD, SEM and statistical X-EDS measurements. The conditions for the densification of Th 1-x Y x O 2-x/2 ceramics were further determined by dilatometry (T ¼ 1575 C, t ¼ 8 h) resulting in densification rates up to 99%. Finally, a first estimation of the electrical properties of the solids was undertaken by impedance spectroscopy. Electrical conductivity was found to increase linearly with the incorporation of Y 3þ content while the associated values of activation energy decreased, with a minimum value of 1.1 eV for Th 0.85 Y 0.15 O 1.925 .