Effects of TiO₂ on the structure and coloration of azure glaze

In this paper, the azure glaze is prepared by using kaolin, calcite, and quartz as the main raw materials fired at a reducing atmosphere. Coloration and structure of the azure glaze are analyzed by the ultraviolet–visible photometer (UV–Vis), colorimeter, X-ray patterns (XRD), scanning electron microscope (SEM), and X-ray photoelectron spectroscopy (XPS). The coloration mechanism is proposed. The results show that: when TiO₂ content is increased, the glaze color gradually changes in sequence: azure → green → yellow → orange → dark orange, which is due to inhibit the reduction of Fe³⁺ and thus Fe²⁺/Fe³⁺ gradually decreases with the increase of TiO₂ content_. The number of bubbles in the glaze layer significantly decrease, and the size of the bubbles increases, which improve the reflect light ability and make the azure glaze opacification like jade. The results would provide a scientific basis and enrich the literature on the history of ceramic manufacturing techniques for the azure glaze.