Study of Some Trapped Hole Centers in X-Irradiated Alkali Silicate Glasses

A detailed study has been made of the EPR spectra of trapped hole centers formed by x irradiation in alkali silicate glasses. The spectra of the five alkali silicate glasses were studied as a function of composition, microwave power, and bleaching temperature. It was found that the spectra could be...

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Veröffentlicht in:J. Chem. Phys., 47: 818-30 (July 15, 1967) 47: 818-30 (July 15, 1967), 1967-01, Vol.47 (2), p.818-830
1. Verfasser: Schreurs, J. W. H.
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Sprache:eng
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Zusammenfassung:A detailed study has been made of the EPR spectra of trapped hole centers formed by x irradiation in alkali silicate glasses. The spectra of the five alkali silicate glasses were studied as a function of composition, microwave power, and bleaching temperature. It was found that the spectra could be decomposed into two separate hole spectra. The intensity ratio of these two spectra depends on the alkali-to-silica ratio. The center more abundant in the low-alkali silicate glasses is called Hole Center 1, HC1; the center more abundant in the high-alkali silicate glasses is called HC2. Helpful in separating the two spectra was a dual cavity technique, which makes it possible to obtain sum and difference spectra. The spectra of both centers are fundamentally the same in all alkali silicate glasses, but differences in detail are shown to be due to a relatively small interaction with neighboring alkali ions. Both centers show a distribution in the thermal stability and associated spectral parameters. The proposed model for HC1 is a hole located on a Si–O tetrahedron with two nonbridging oxygens, and with the hole presumably largely restricted to these nonbridging oxygens. The proposed model for HC2 is quite similar, but the tetrahedron now has three nonbridging oxygens. A comparison of the optical and EPR difference spectrum of two potassium silicate glasses with different (K2O)-to-(SiO2) ratios suggests that the 475-nm optical absorption band may be due to HC1.
ISSN:0021-9606
1089-7690
DOI:10.1063/1.1711956