Micro-Raman Study of Chinese Iron-Based Brown Wares Produced During Song Dynasty (960–1279 CE): Probing Crystals in the Glazes

Brown glazed wares, as some of the famous Song wares, attract significant attention nowadays due to the glaze containing a large amount of metastable ε-Fe2O3, a promising multiple-functional electromagnetic material. In this work, typical fragments were systematically analyzed by micro-Raman spectroscopy combined with scanning electron microscopy as well as X-ray fluorescence. Abundant ε-Fe2O3 crystals were observed in the glaze surfaces, with the exception of numerous hematite crystals detected in the surfaces of fragments excavated in Hunyuan kilns (Shanxi province). The correlative analyses of Raman and XRF data indicate that relatively high SiO2 and low CaO contents in the system may benefit ε-Fe2O3 precipitation, and the crystallization temperature may range from 1150 to 1200 °C. In addition, various crystals were detected in the glazes, including magnetite, magnesioferrite, zircon, anatase, pseudobrookite, rutile, cordierite, cristobalite, quartz, and mullite.