Achieving tunable sky-blue copper glaze and coloring mechanism by the introduction of phosphorus

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 t 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.