Hollow ceramic microspheres by sol-gel dehydration with improved control over size and morphology

Hollow microspheres of ceramic material are formed by a sol-gel technique involving forming and stabilizing an emulsion of an aqueous sol of the ceramic material in an organic phase, followed by dehydration of the stabilized emulsion droplets by extraction using a water-absorbing organic liquid, to form hollow gelled spheres, and finally recovery, drying and calcination of the spheres to the final product. The separation of the emulsion formation and dehydration steps into two distinct stages results in the ultimate formation of microspheres with improved uniformity and size distribution.