Technological study on the firing process of celadon wares from the Xiajian kiln

To investigate the characteristics of raw materials and firing technology employed in celadon wares produced at the Xiajian kiln, a series of analytical techniques-including colorimetry, X-ray fluorescence spectrometry (XRF), super-depth-of-field microscopy (SDM), and X-ray photoelectron spectroscopy (XPS)-were applied to representative ceramic samples. The study analyzes chromatic properties, microstructural features of both the body and glaze, chemical compositions, and the valence states of coloring elements. The results indicate that the ceramic bodies exhibit a "high-silica, low-alumina" composition, characteristic of southern celadon traditions. Alkali metal oxides serve as the primary fluxing agents, while the relatively high Fe₂O₃ content in the body produces a dark gray hue that significantly affects glaze brightness. The glaze is identified as a calcium-based glaze supplemented with plant ash as an auxiliary flux. Additionally, elevated levels of TiO₂ suggest the intentional addition of rutile. XPS analysis reveals a gradient in Fe³⁺ concentrations between the body and glaze, attributable to structural distortion in ferrous phases induced by Ti⁴⁺ in the glaze, leading to increased Fe³⁺ formation. This mechanism is identified as the key factor contributing to the yellowish tint within the celadon's green tone. The study elucidates the synergistic mechanism among raw material formulation, elemental valence state transitions, and kiln atmosphere, providing mineralogical and materials-science evidence for the firing and coloration techniques of Five Dynasties celadon.