Effect of Y2O3 addition on the phase transition and growth of YSZ nanocrystallites prepared by a sol–gel process

The effect of Y2O3 addition on the phase transition and growth of yttria-stabilized zirconia (YSZ) nanocrystallites prepared by a sol–gel process with various mixtures of ZrOCl2·8H2O and Y(NO3)3·6H2O ethanol–water solutions at low temperatures has been studied. DTA/TGA, XRD, SEM, TEM and ED have been utilized to characterize the YSZ nanocrystallites. The crystallization temperature of 3YSZ, in which Y2O3/(Y2O3+ZrO2)=0.03, gel powders estimated by DTA/TG is about 427°C. When 3YSZ and 5YSZ gels are calcined at 500–700°C, their crystal structures as composed of coexisting tetragonal and monoclinic ZrO2, and tetragonal phase decreases with calcination temperature increasing from 500 to 700°C. Pure cubic ZrO2 is obtained when added Y2O3 is greater than 8mol%. A nanocrystallite size distribution between 10 and 20nm is obtained in TEM observations.