Effect of sedimentation mediums on opal template fabrication from monodispersed silica under gravitational field

The monodispersed silicon dioxide spherical particles were synthesized by improved Sol-gel methods, tetraethoxysilane as silicon material, ammonia as catalyst and ethanol as solvent. The sedimentation and organization of silica spheres with mean diameter of about 250nm, 280nm and 320nm in different mediums of distilled water, ethanol, acetone and water-ethanol mixture were investigated. Images by SEM show the gravity sedimentation of monodispersed silica particles in ethanol or acetone can form three-dimension closed packing structural opal, and ethanol is superior to acetone in opal fabrication. Silica spheres sedimentation experiment indicated that the velocity of isometric silica microspheres sedimentation in water, ethanol and acetone has little difference. The influence of sedimentat