Ceramics-Silikáty 69, (4) 589 - 600 (2025)

This study investigates the coloration mechanism of Lang red glaze by exploring the coupling among the microstructure, copper valence states, and optical properties under crystal nuclei induction. Using K-feldspar, kaolin, CuO, and SnO₂, the glaze formulation was optimised through single-factor and L₉(3⁴) orthogonal experiments. The influence of the process parameters-such as the ball milling time, glaze thickness, and firing temperature-was also evaluated. The XRD analysis confirmed an amorphous glass matrix with minor anorthite crystallisation. The SEM and EDS revealed a worm-like phase-separated structure with nanoscale domains (∼28 nm) conducive to Mie scattering. The XPS indicated that the copper exists predominantly as Cu^⁺(80.94%), with SnO₂ assisting in its stabilisation and in the uniform formation of Cu₂O colloids. These results support a ternary colouration mechanism driven by “crystal nucleation-valence control-optical scattering,” where phase separation facilitates the spatial distribution and optical enhancement of copper colloids. This work provides a scientific basis for recreating stable red glazes and offers insights into traditional Chinese ceramic aesthetics from a materials science perspective.