| abstract |
Hollow and spherical silica-based fine particles having a porous material and/or cavities inside an outer shell provide silica-based fine particles exhibiting a low refractive index. The above silica-based fine particles are produced by a method comprising growing porous composite oxide particles (primary particles) while adjusting the ratio of addition of a silica source and a source of an inorganic oxide except silica, and then removing the inorganic oxide except silica, to thereby prepare a dispersion of the above hollow and spherical silica-based fine particles, then optionally washing the dispersion, aging at a temperature ranging from an ordinary temperature to 300˚C, and subjecting the dispersion to a hydrothermal treatment at a temperature ranging from 50 to 300˚C. |