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.