Protocollo di fabbricazione per via colloidale di cristalli fotonici 3 D

We present the details of the Sol-gel processing used to synthesize silica spheres, with particular attention to the conditions that permit to tailor their dimension. We have elaborated a protocol in order to obtain silica micro spheres with low polydispersivity and we have demonstrated that large well-ordered crystals of synthetic opal, that exhibit a photonic stopband, can be produced in few days by vertical deposition and evaporation-assisted sedimentation deposition methods. Scanning electron microscope was employed to characterize the samples reflectance and transmission measurements were used to put in evidence the high quality of the realized opals.