Synthesis of zirconia-alumina and alumina-zirconia core-shell particles via a heterocoagulation mechanism

This study describes the synthesis of core-shell particles, consisting of a ZrO2 or Al2O3 submicron nucleus coated by a nanolayer of Al2O3 or ZrO2, respectively. The oxide layers around the cores are deposited via a heterocoagulation route, based on the attraction of oppositely charged core and shell particles. TEM micrographs clearly show a homogeneous Al2O3 shell (originating from boehmite or gamma-Al2O3 particles) around the ZrO2 cores and in the other case, a ZrO2 layer (originating from hydrothermally prepared ZrO2) around the submicron Al2O3 cores. From PCS measurements, it can also be deduced that the cores are enwrapped by a shell and it is calculated that the thickness of the Al2O3 shell is about 30-35 nm and the ZrO2 layer is approximately 80 nm. The coated powders are additionally characterized by XRD. (c) 2005 Elsevier Ltd. All rights reserved.