Fabrication and properties of multilayer-coated core–shell structural monodisperse spheres and close-packed structure

Silica layer and silver layer were successively deposited on the surface of submicron silica spheres through electroless plating approach to fabricate multilayer-coated core–shell structural monodisperse spheres, SiO2@Ag@SiO2, for photonic crystals use. High quality silver layer with dense and uniform structure was verified by UV–visible absorption spectra and energy dispersive X-ray microanalysis (EDX). The metal-dielectric spheres SiO2@Ag@SiO2 with 300 nm in diameter crystallize directly into close-packed structure by self-organisation method, and directional photonic band gaps (PBGs) for the photonic crystal were found in optical and near infrared wavelengths.