PREPARATION OF THO2/Y2O3 POWDERS BY THE SOL-GEL METHOD FOR SOLID ELECTROLYTES

Stable Th/Y oxide sols were prepared by peptization of the washed hydroxides and converted by different solidification methods to sinterable ThO2/Y2O3 powders which were compared with coprecipitated ThO2/Y2O3 powder. The best powder properties were obtained if the Th/Y oxide sol was solidified by internal gelation. Slip casting and subsequent cold isostatic pressing of the sol-gel-derived powder resulted in densities of sintered crucibles or plates of 98.8%, direct cold isostatic pressing in 99.5% of the theoretical density. EMF measurements using sol-gel-derived ThO2/Y2O3 plates gave results which agreed with data from measurements using ZrO2/Y2O3 solid electrolytes and with literature data.