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 xCaF(2)(50 - x)CaO . 50SiO(2) (x = 5, 10, 15, 20, and 25 mol%) and x-CaF2(50 - x/2)CaO(50 - x/2)SiO2 (x = 5, 10, 15, and 20 mol%). The analysis of the F1s 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 O1s spectra, and the network of the fluorine-containing glasses was concluded to depend only on the ratio CaO/SiO2.