Effect of grain size on the sinterability of yttria nanopowders synthesized by carbonate-precipitation process

Yttria nanopowders have been synthesized by carbonate precipitation process. The thermal decomposition behavior of the carbonate precipitate, crystal phase, microstructure and sinterability of the powders were examined. The precipitate precursor was decomposed completely at 700 °C and then crystallized well into cubic yttria phase. Our results suggested that the most favorable calcination temperature was 1100 °C for obtaining good dispersion, high-reactive yttria nanopowders. The nanopowders were almost spherical and had weak agglomeration and narrow particle size distribution with a mean grain size of about 80 nm. Using these yttria nanopowders, nearly full dense yttria ceramic with ∼99.2% of theoretical density was obtained at 1600 °C for 2 h without any additives.