On the local coordination of Fe in Fe2O3-glass and Fe2O3-glass ceramic systems containing Pb, Na and Si

Abstract The effect of the composition and casting temperature on the structural role of Fe in a series of binary (Fe 2 O 3 –PbO and Fe 2 O 3 –Na 2 O) and ternary (Fe 2 O 3 –PbO–SiO 2 ) glass and glass ceramic materials is studied by means of X-ray fluorescence (XRF) mapping, X-ray absorption fine structure (XAFS) and Mossbauer spectroscopies. According to the Mossbauer results the majority of Fe exists in the Fe +3 state. The XRF maps reveal that Fe-rich islands evolve into the vitreous matrix of ternary samples that contain more than 40 wt% Fe 2 O 3 . In these samples the XAFS results disclose that 40–43 at.% of the Fe atoms belong to the Fe-rich microcrystalline islands formed by Fe x O y oxides. Furthermore, the structural role of Fe +3 in the ternary glasses is found to depend on the Fe 2 O 3 content. Finally in the binary Fe 2 O 3 –PbO systems the majority of Fe +3 is octahedrally coordinated in the Fe 2 O 3 and/or PbFe 12 O 19 crystalline phases.