Metastable phase formation during flame spray pyrolysis of ZrO2(Y2O3)–Al2O3 nanoparticles

Nanoparticles with the composition (1 − x mol.%) [ZrO2 (3 mol.% Y2O3)]–(x mol.%) Al2O3, with x ranging from 0 to 1, were prepared by liquid-feed flame spray pyrolysis. The effect of the alumina content on the morphology and phase formation was studied by means of X-ray diffraction, nitrogen adsorption and transmission electron microscopy. It is shown that alumina can be incorporated into the nanoparticles at levels above the solubility limit, leading to the formation of metastable extended solid solutions and core–shell nanoparticles.