Densification of zirconia doped yttria transparent ceramics using co-precipitated powders

Ho:Y2O3 ceramics were prepared using co-precipitated powders, with ammonium sulfate as dispersant. Y3+ was co-precipitated together with Ho3+ and Zr4+ to produce precursors, which were calcined at 1100-1400 degrees C to produce yttria-based powders. At calcination temperatures of <= 1300 degrees C, agglomeration of powders was not observed. When the temperature was increased to 1400 degrees C, severe agglomeration was detected. Densification was closely related to the calcination temperature: a lower calcination temperature resulted in a faster densification of ceramics to the relative density of 99.7%. The ultimate densification to similar to 100% was also closely related to powders' impurity level and agglomeration. Grain growth was mainly determined by sintering temperature, but not by the initial crystallite size of powders. The optimal calcination temperature was 1300 degrees C, at which the obtained Ho:Y2O3 powder was free from agglomeration. Using this powder, the resultant Ho:Y2O3 ceramics showed pore-free microstructure and good optical transparency. (C) 2016 Elsevier Ltd and Techna Group S.r.l. All rights reserved.