Journal of the Ceramic Society of Japan 106 [4] 415-421 (1998) Paper X-Ray Photoelectron Spectroscopy of Alkali Silicate Glasses Syuji MATSUMOTO, Tokuro NANBA* and Yoshinari MIURA* Department of Materials Science, Graduate School of Natural Science and Technology, Okayama University, 3-1-1, Tsushima-Naka, Okayama-shi 700-8530 * Department of Environmental Chemistry and Materialș Faculty of Environmental Science and Technology, Okayama University, 2-1-1, Tsushima-Naka, Okayama-shi 700-8530 X-ray photoelectron spectra were measured on the fresh surfaces of silica, binary alkali silicate and mixed alkali silicate glasses fractured in ultra-high vacuum by irradiating with focusing monochromatic AlKƒ X - ray. Binding energies and chemical shifts of O1s, Si2p, Li1s, Na1s, K2p, Rb3d5/2 and Cs4d5/2 have been in vestigated, and charge densities of oxide, silicon and other alkali ions have been discussed. For xna2o E (100-x)SiO2 glasses, electron densities of bridging oxide ion (BO), non-bridging oxide ion (NBO) and sodium ions increased with increasing the Na2O content, suggesting that the bond order between O2p and Na3s (or 3p) increased with increasing the Na2O content. In addition, the difference in binding energies be tween BO1s and NBO1s decreased with increasing Na2O content indicating that electrons were delocalized considerably in O2p-Si3d ƒî bonds. For 33.3R2O E66.7SiO2 (R=Li, Na, K, Rb, Cs) glasses, charge densities of BO increased with increasing ionic radius of alkali ions (Li Na K, Rb Cs). The degree of polarization of BO increased with increasing ionic radius of alkali ions. For 33.3{(1-y)Li2O EyCs2O} E66.7SiO2 glasses, O1s peak of NBO could not been discriminated between the components belonging to Si-O- cli+ and Si-O- c Cs+. O1s chemical shifts of 33.3{(1-x)Li2O ExCs2O} E66.7SiO2 glasses with increasing Cs2O content were similar to the shifts of 33.3R2O E66.7SiO2 glasses with increasing ionic radius of alkali ions. The area-weigh ed mean values of O1s peaks appeared to have good correlation with an empirical expression of optical basici ty. [Received November 7, 1997; Accepted January 21, 1998] Key-words: Alkali silicate glass, Mixed alkali silicate glass, X-ray photoelectron spectroscopy, Electronic state, Local structure, Lewis basicity
Table 1. Binding Energies and Full Widths at Half Maximum (FWHM) in the Core Level Photoelectron Spectra, and Peak Area of NBO in the O1s Signal for xr2o E(100-x) SiO2 (R=Li, Na, K, Rb and Cs) Glasses [A] and 33.3{(1-y)Li2O EyCs2O E66.7SiO2 Glasses [B]. BO and NBO Represent Bridging and Non-Bridging Oxide Ions, Respectively. rnbo Represents Peak Area of O1s Signal of NBO [A] xr2o E(100-x)SiO2 (R=Li, Na, K, Rb and Cs) Masses. [B] 33.3{(1-y)Li2O EyCs2O} E66.7SiO2 glasses.
Fig. 1. X-ray photoelectron spectra of 33.3R2O E66.7SiO2 (R=Li, Na, K, Rb and Cs) glasses. Fig. 3. O1s binding energy as a function of Na2O content for xna2o E(100-x)SiO2 glasses. Lines are obtained by least square calculation. (a) (b) (c) Fig. 2. O1s (a), Si2p (b) and Na1s (c) photoelectron spectra for xna2o E(100-x) SiO2 glasses.
Fig. 4. O1s photoelectron spectra for 33.3R2O E66.7SiO2 (R=Li, Na, K, Rb and Cs) glasses. Fig. 5. O1s photoelectron spectra for 33.3{(1-y)Li2O EyCs2O} E 66.7SiO2 glasses. Fig. 6. Ols binding energy as a function of y for 33.3{(1-y) Li2O EyCs2O} E66.7SiO2 glasses. Lines are obtained by least square calculation.
Fig. 8. Relations between O1s binding energy and optical basici ty, ƒ cal, for R2O-SiO2 glasses investigated in this study, together with the results for R2O-B2O312) and R2O-TeO27) glasses. Fig. 7. Relations between O1s binding energy and optical basici ty, ƒ cal for R2O-SiO2 glasses. Lines are obtained by least square calculation.
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