Structural colors derived from colloidal crystals are gaining attention as new color materials that are non-toxic and minimize environmental pollution.Vivid structural colors were formed by coating glass and ceramics with a colloidal crystal (opal) thin film composed of silica particles.This paper focuses on reporting this thin film formation process.A milky-white suspension of silica particles (particle size 290 nm) precisely arranged on the substrate surface exhibited vivid red structural color after drying.The dip coating is not limited to flat substrates like glazed ceramics or glass; it is versatile and can be applied to curved surfaces, uneven surfaces, and even rough, unglazed ceramic surfaces.Optical evaluation utilized reflectance spectra.By employing silica opal films with varying particle sizes, diverse colors spanning the entire visible spectrum from blue to red were achieved.Furthermore, through heat treatment and modification to create a hydrophobic surface, stable structural color emission was enabled, preventing loss of color due to abrasion or wetting.
Hiroshi Fudouzi (Thu,) studied this question.