Preparation of porous zirconia microspheres via emulsion method combined with phase separation

Abstract Porous zirconia (ZrO 2 ) microspheres with incontinuous multicavities were prepared via emulsion method combined with phase separation in the presence of polyvinylpyrrolidone (PVP). The morphology of the microspheres is derived from the spherical oil droplets by high-speed shearing and the sol–gel reaction on the droplets, while the PVP acts as a phase separation inducer to form incontinuous multicavities inside the microspheres. The addition of PVP does not change the particle size distribution and smooth surface morphology of the microspheres, while the size of cavities inside microspheres increases gradually with the increase in PVP amount. The particle characteristics, phase transformation and cavity formation mechanism of porous ZrO 2 microspheres are analyzed in detail. Graphical Abstract Porous ZrO 2 microspheres with incontinuous multicavities were prepared via emulsion method combined with phase separation in the presence of polyvinylpyrrolidone (PVP). The morphology of the microspheres is derived from the spherical oil droplets by high-speed shearing and the sol–gel reaction on the droplets, while the PVP acts as a phase separation inducer to form incontinuous multicavities inside the microspheres. A schematic illustration of the formation mechanism of ZrO 2 microspheres with PVP and without PVP