An x-ray photoelectron spectroscopic study of the chemical states of fluorine atoms in calcium silicate glasses

X-ray photoelectron spectroscopy has been used to examine the chemical states of fluorine in the glasses of composition _xCaF₂(50 – x)CaO · 50SiO₂ (x = 5, 10, 15, 20, and 25 mol %) and _xCaF₂(50 – x/2)CaO(50 – x/2)SiO₂ (x = 5, 10, 15, and 20 mol %). The analysis of the F1_s spectra indicated that Ca²⁺ and F^- ions introduced as CaF₂ are favorably located among the Si–O skeleton forming Ca–F clusters. The fraction of the bridging and nonbridging oxygen atoms was derived from the O1_s spectra, and the network of the fluorine-containing glasses was concluded to depend only on the ratio CaO/SiO₂.