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This work was aimed to explore the relationship between phosphorus and coloring of copper glaze under oxidizing atmosphere. The phase, microstructure and chemical state of the samples were investigated by X-ray diffraction, Scanning electron microscopy, Raman spectroscopy and X-ray photoelectron spectroscopy. The results indicated that the addition of phosphorus broke up the silica network and decreased the viscosity of glaze melt, and then promoted the formation of discrete droplet phase-separated structures. Thus, blue opalescence was formed by the Rayleigh scattering on the sky-blue copper glaze surface. In addition, the reversed polarization of P5+ acted on the Cu–O bond and decreased the ratio of Cu2+ and Cu+. It increased the number of non-bridging oxygens and the spatial density of oxygen atoms around Cu2+, which was the essence of the copper blue glaze. Coupling of the structural color and the chemical color made the sky-blue copper glaze get more vivid.

In this paper, the phase-separated structures and the effective refractive index of the sky-blue glaze of Jun ware were investigated to determine the forming conditions of structural colors caused by amorphous photons crystals. It showed that with separation structures of short range order and average diameter of 106–260 nm, the structural color of amorphous photons could be formed in the glaze. In order to verify them and study the effect of colorant by the experimental method, the phase separation glazes were prepared with different contents of iron ore slag. The results indicated that the addition of colorant not only increased the effective refractive index of glazes, but also darkened the glaze color and suppressed incoherent scattering. Therefore, structural colors deepened with the increasing of colorant contents. Deciphering the ancient nanotechnology could thus potentially help researchers prepare colorful glazes by the green environmental protection method.

The moon-white glaze was successfully reproduced with the addition of 0.02 wt% silicon carbide (SiC) for supplying carbon (C) and reducing iron oxide (Fe 2 O 3 ) at 1250 °C. Effects of the SiC contents on the chromaticity, precipitated phase and microstructure of moon-white glaze were investigated. Based on the analysis of colorimeter, XRD, XPS, FT-IR, SEM and TG–DSC, a possible coloring mechanism was proposed to explain the variation of glaze colors with the increasing of SiC content. The results indicated that the addition of SiC contributed to increasing the content of C and the size of phase separation droplets in glazes. The formation of C increased the ratio of Fe 2+ to Fe 3+ and the increased size of phase separation droplets weakened the structural color, which increased the L* and b* value of glazes. Therefore, the color of moon-white glaze got more blue and white gradually.