Colour-generating mechanism of copper-red porcelain from Changsha Kiln (A.D. 7th–10th century), China

Changsha Kiln, located at Changsha in Hunan Province, south of China, is famous for exported and coloured porcelain during the Tang Dynasty (A.D. 7th-10th century) period. Although the opinion that copper-red porcelain originates from Changsha Kiln is widely accepted in academic circles, chemical characters of glaze and colour mechanism of its copper-red porcelain have not been fully investigated and studied. Therefore, a shard of opaque glaze porcelain with red pigments which excavated at Changsha Kiln (A.D. 7th-10th century) was analyzed by Energy dispersive X-ray fluorescence (EDXRF), Synchrotron X-ray absorption near-edge spectroscopy (XANES), micro X-ray diffraction (μ-XRD), microscopy and scanning electron microscopy (SEM) methods. Combining with XANES and μ-XRD results, it indicates that metal copper is the major colouring-generation element status of the red hue. On the other hand, for the first time the study demonstrates that glaze of the sample from Changsha kiln is a typical phase separated-crystalline glaze with large particles surrounding acicular crystals which lead the opaque appearances. Because the sample from Changsha Kiln is Chinese ancient early stage copper-red porcelain relic, it will help to understand the origin of copper-red porcelain in China and enrich the knowledge of Chinese ancient ceramic culture.