Chemical evolution of lead in ancient artifacts -A case study of early Chinese lead-silicate glaze

摘要

Early Chinese lead glaze has been recognized as an important artifact due to its multiple significances in history and science. Some efforts were made to explore its composition and degradation, but the chemical mechanisms of glaze transformation and incrustation formation, especially the evolution of lead and the roles of colorants, are still not clearly elucidated. In this work, an amorphous Si-rich structure and a layer of dendritic PbCO3 crystal were detected in the degraded glaze. Such characteristics of the incrustation help to attain insights into the chemistries governing glaze decomposition, re-crystallization of the lead compound and formation of the multi-layered structure. In addition, comparative studies on newly constructed lead-based glazes provide solid evidences for the lead transformation and highlight the crucial role of colorants in the glaze degradation. These fresh findings enable better understandings of the lead-silicate glass material and clarify long-term transformation of lead in burial environments.