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 degrees C and then crystallized well into cubic yttria phase. Our results suggested that the most favorable calcination temperature was 1100 degrees 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 similar to 99.2% of theoretical density was obtained at 1600 degrees C for 2 h without any additives. (c) 2008 Elsevier B.V. All rights reserved.