Analysis of ferrosilicon and silicon carbide by an X-ray fluorescence fusion method - An X-ray diffraction investigation of the preliminary oxidation

An X-ray diffraction (XRD) investigation was undertaken to clarify the processes occurring during the oxidation of ferrosilicon and silicon carbide in the presence of lanthanum oxide, with the aim of optimising the technique to give a product that is easy to fuse with lithium tetraborate into a bead suitable for X-ray fluorescence (XRF) analysis, It was found that the addition of both iron and carbon powder was necessary to ensure that complete oxidation had occurred, and that no reduced species remained to damage the platinum ware in the fusion process. Lanthanum oxide participated in the oxidation reaction and lanthanum silicates were produced, Manganese has been shown to be a suitable alternative to iron, which then enables iron to be determined in the samples. Silicon was determined by XRF in the certified reference material Euronorm-MRC No 582-2 at 75.1% with a standard deviation of 0.2% absolute (certified value 75.2%, standard deviation 0.2%).