EPR study of the E’ defects in optical glasses and cristobalite

Abstract

The electron paramagnetic resonance (EPR) in experimentaloptical glasses obtained from the East Sayan mountain quartzites has beenstudied. For comparison a powder sample of cristobalite that formed duringthe beneficiation process of quartzite was also investigated by EPR. Thecomplex EPR spectra of fast-electron-irradiated glass andcristobalite were treated by computer simulations to determine the types of centers and their principal gvalues. In glasses the well-known paramagnetic centers , , have been observed. In particular, thecenter previously characterized as stableonly below was observed as a stable variantat room temperature. In cristobalite the paramagnetic defects similar to the , , centers with slightly differentg values have been observed. From the observation of analogous centers it was inferred that local structuresof glass and -cristobalite aresimilar.

Difference in Structure and Electronic Properties of Oxygen Vacancies in α-Quartz and α-Cristobalite Phases of SiO2

“…In -Q, the most stable center was the , which was a close relative to the family of centers in a-SiO 2 , the general structure of which can be seen in Figure 2 c. The center naming convention uses Greek letters for a-SiO 2 and Arabic numerals for -Q. Recent electron paramagnetic resonance (EPR) studies distinguished at least 15 different EPR signals attributed to centers in different types of -Q perturbed by different defects and impurities [ 23 , 24 , 25 ].…”