LAUSR

Abstract A powder with core-shell morphology was used to obtain a dense yttrium-aluminium garnet material. Precipitation of a Y 2 O 3 precursor in an aluminium oxide slurry, using ammonium carbonate, allowed nanometric particles of the yttrium oxide precursor to be deposited on submicron Al 2 O 3 grains. It was found that washing of the precipitation product changes the chemical composition of the precursor which has a significant impact on the evolution of a phase composition of powders during the heat treatment process and finally on their morphology. Pressureless sintering at 1650 °C for 2 h of the unwashed powder led to a single-phased material without open porosity reaching approx. 96% of the theoretical density while during sintering under the same conditions the compact of the washed powder did not completely close pores and its density was not higher than 92%. The use of isostatic hot-pressing process allowed a complete elimination of porosity in the materials obtained from the unwashed powder to occur.