WANG Chao
(Wuxi Institute of Arts and Technology, Yixing, 214206, Jiangsu, China)
Abstract: Crystalline glaze with smooth surface and high yield was prepared with the highest firing temperature of 1220 ℃ in oxidizing atmosphere, thus solving the problems of the traditional body of crystal glaze, such as single color, high firing temperature (>1300 ℃) and poor quality. It was found that the presence of the pigment iron oxide could make the glaze to have golden flower patterns with a purple opaque background, while the combination of iron oxide and nickel oxide resulted in glaze with beautiful flowers and a dark blue opaque background. Combined with X-ray diffraction analysis (XRD), scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS), microstructure of selected samples was studied. The crystalline glaze contained crystals with mainly an acicular structure. There were a large number of separative-phase structures in the glass phase, such as silicon-rich microspheres with an average size of 300 nm, nanoscale interconnected sponge mesh structures and ZnFe2O4 spinel crystals grown parallelly to the glaze layer. The blue and purple base colors of the crystalline glaze were not caused by the chemical coloring of iron oxide and nickel protoxide, while the size characteristics of the micro-nano structures caused coherent scattering and comprehensive optical effect on light, thus leading to typical structural color, so that the glaze appeared blue and purple opaque base colors. The results of this study could be used as a reference to the study of the coloration mechanisms in ancient ceramics.
Key words: ceramic; crystalline glaze; phase-separation; structural color