关键词: 圆明园;琉璃瓦;颜色变化

Abstract: Optical microscopy, energy-dispersive X-ray fluorescence (EDXRF), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were used to analyze the reddening phenomenon noted for some glazed tiles and unearthed at Yuanmingyuan to study the mechanism that caused the color change and associated firing processes.Combining the above results, it can be concluded that the glaze of the glazed tiles was a type of lead-silicate composite, the green and red are caused due to Cu valence and content in different glaze, and Cu ions in the green regions mainly existed as Cu2+, while the Cu ions in the black-red and bright red regions that were originally all green coexisted as Cu+ and Cu0.Therefore, Cu0 plays a major role in the red coloration.However the main reason for the color change of the glazed tiles from green to black-red and bright red was great fire of Yuanmingyuan, when the fires died out produced reducing substances like C and CO which resulted in the reduction of Cu2+ to Cu0 and Cu2O, then precipitated and aggregated on the surface of the glaze, and its mechanism is identical to the one that copper red glaze has worked.

Key words: Yuanmingyuan;glazed tile;color change