Mِssbauer spectroscopy and neutron activation analysis of ancient Chinese glazes

The optical spectra of the glaze of Ru porcelain made in the Chinese Northern Song Dynasty (AD 960–1126) were measured by the chromatometer to determine the relations between glaze color and its dominant wavelength (λD). The concentrations of 30 coloring elements in the glaze were determined by neutron activation analysis (NAA). Iron was the dominant coloring element. Mössbauer spectroscopy detected that iron existed in the state of structural Fe2+ and Fe3+ ions. A relationship between λD of various colored glazes and the Fe2+/Fe3+ ratio was established. As the Fe2+/Fe3+ ratio gradually increases, the glaze color of Ru porcelain will gradually change from pea green to sky green. All the Ru porcelains were fired in a reducing atmosphere. The sky green Ru porcelain was fired in the most reducing atmosphere and at the highest temperature, the powder green in a more reducing atmosphere and at a lower temperature and the pea green in a lightly reducing atmosphere and at the lowest temperature.