Figure 1.

Observation of structural colors in random metallic networks with subwavelength dielectric coatings. (a) Schematic illustration of an Al₂O₃-coated PtYAl nanomaterial, based on a 3D reconstruction of a completely dealloyed PtYAl thin film obtained via FIB-assisted thin film tomography. (b) Photographs of deposited, dealloyed and Al₂O₃-coated PtYAl metamaterial networks, illustrating the formation of vibrant colors and the continuous color change with increasing coat thickness. The photographs were taken under illumination from ceiling lights. Each image is 2 × 2 mm². (c) Experimental and FDTD simulated structural color reported in a standard CIE 1931 (x, y) space, depicting the chromaticity visible to the average person. The RGB color space is marked by the triangle area. The chromaticity is calculated directly from reflectance spectra obtained either experimentally (circles markers) or by FDTD simulations (dashed line). The edges of the tongue-shaped plane correspond to color values of maximal saturation. (d) Color palette calculated by FDTD simulations for increasing thickness of Al₂O₃. 3D, three-dimensional; RGB, red green blue.