Defects in synthetic quartz: Radiation-induced mobility of interstitial ions

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Abstract
Electron‐spin resonance (ESR) has been used to investigate defect formation, anneal, and migration effects in commercially available high‐quality synthetic quartz. Electronic‐Grade and premium Q material, both unswept and swept, were included in the study and an electron accelerator was used for all irradiations. Previously unreported holelike and electronlike paramagnetic defects have been observed and their production and decay properties are described. The concentration of aluminum‐associated trapped hole centers (now known as [Ale+]° centers) was found to be a strong function of irradiation temperature and previous electrodiffusion (sweeping) treatments. Irradiation of an as‐received unswept sample at 77 K produced very few [Ale+]° centers. If the same unswept sample was irradiated at room temperature and then reirradiated at 77 K, the [Ale+]° center concentration was enhanced by one to two orders of magnitude. The intermediate irradiation at room temperature is believed to remove interstitial Na+ ions from the vicinity of the substitutional aluminum ions and thus allow the aluminum ions to trap holes during the second 77 K irradiation. The onset of the radiation‐induced mobility of the Na+ ions occurs between 200 and 250 K. An intense [Ale+]° center ESR spectrum was found after the initial 77 K irradiation of the as‐received commercially swept samples, and the intermediate room‐temperature irradiation caused no enhancement of the spectrum during a subsequent reirradiation at 77 K. This suggests that radiation‐induced mobility of hydrogen ions occurs at 77 K. As an application of these results, a sensitive testing procedure is described for measuring the extent to which the interstitial Na+ ions have been removed from a synthetic quartz sample by the commercial sweeping process.

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