Analysis of the chemical composition and phase structure of ‘Ru-type ware’ bodies under the influence of firing temperature

Abstract The Qingliang Temple kiln located in Baofeng County, Henan Province, China, is the discovery site of Ru Kuan porcelain, which is one of the five famous porcelain types of the Song dynasty in China. The ‘Ru-type ware’ and unglazed firing bodies were unearthed from the Qingliang Temple kiln in 2014, and the excavation site was very close to the central firing area of Ru Kuan porcelain. In this paper, the chemical composition, firing temperature and phase structure of the Ru-type ware and unglazed firing bodies from the Qingliang Temple kiln were analysed systematically using energy-dispersive X-ray fluorescence spectrometry, high-temperature thermal expansion and X-ray diffraction. The raw-material sources of the Ru-type ware bodies with various glaze colours are consistent but differ significantly from those of the unglazed firing bodies. The firing temperatures of the Ru-type ware and unglazed firing bodies are 1150–1200°C and 950°C, respectively, which are considered underfired. Mullite, α-quartz, β-cristobalite and α-Fe2O3 are the main constituents of the Ru-type ware bodies, whereas α-quartz and anatase were identified in the unglazed firing bodies. The Ru-type ware is related to the Ru Kuan ware in terms of firing techniques and official use.