Dynamic study of ammonium dawsonite doped with yttrium transformation at elevated temperatures

Co-precipitation of alumina/YAG precursor from aluminum and yttrium nitrates solution with ammonium carbonate results in dawsonite (NH 4 Al(OH) 2 CO 3 ). Its crystallographic parameters differ from the compound precipitated without the yttrium additive. It indicates that yttrium ions become incorporated into the dawsonite structure. The DSC/TG and X-ray measurements show decomposition of dawsonite at elevated temperature resulting in γ-Al 2 O 3 which transforms to δ and θ modifications at still higher temperatures. The full transformation to α-Al 2 O 3 and YAG occurs at temperatures higher than 1,230 °C.