Infrared characterization of aluminum and hydrogen defect centers in irradiated quartz

Abstract

As-received and 60Co-irradiated cultured quartz is characterized using low-temperature near-infrared Fourier spectroscopy, and peaks associated with as-grown hydroxide (OH) and aluminum hydroxide (Al-OH) point-defect centers are measured. Defect-center distributions are determined from scanning small crystal regions parallel or normal to the crystal-growth axis. Large variations in point defects are observed arising from variations in substitutional and interstitial impurity concentrations along the crystal-growth axis. For the initial radiation doses as-grown OH decreases uniformly across the crystal and forms Al-OH, but Al-OH peak strength varies considerably in different crystal sections. This indicates the possibility of radiation-induced hydrogen diffusion over large distances to compensate nonuniformities in aluminum-ion distribution. With increasing dose as-grown OH may stabilize to a constant level in some crystal regions but deplete in other sections. For some crystals, Al-OH continues to form even after all as-grown OH is depleted, indicating an additional internal hydrogen-ion source. Sweeping (electrodiffusing) an irradiated sample in an air atmosphere restores as-grown OH, retains the radiation-induced Al-OH, and in samples with high as-grown OH concentrations creates a series of small bands in the frequency range of 3450 to 3625 cm−1.

Cathodoluminescence characterization of tridymite and cristobalite: Effects of electron irradiation and sample temperature

“…This blue CL emission of quartz is assigned to the following factors. The center is related to [AlO 4 /M + ] 0 defects closely associated with Al 3+ impurity substituting for Si 4+ in the Si-O tetrahedra as well as monovalent cations (M + : Li + and Na + ) and hydrogen acting as a charge compensator ion situated at interstitial positions, e.g., in channels parallel to the c axis for quartz (Lehmann and Bambauer 1973;Hanusiak and White 1975;Sibley et al 1979;Halliburton et al 1981;Jain and Nowick 1982;Jani et al 1983;McKeever et al 1985;Lipson and Kahan 1985;Halperin 1991;Ramseyer and Mullis 1990;Perny et al 1992;Bahadur 1994;Gorton et al 1996). Such assignment of the short-lived blue luminescence agrees with the fact that the Al 3+ impurity accompanied by Li + and Na + shows a positive correlation with CL intensity of the blue emission band (Ramseyer and Mullis 1990;Perny et al 1992).…”

Polarized IR spectra of synthetic smoky quartz

“…1979;Halliburton et al 1981;Lipson and Kahan 1985). The wavenumbers of the three Yon bands are given here as determined from these studies.…”

Correlating the TL response of γ-irradiated natural quartz to aluminum and hydroxyl point defects

“…For instance, it was showed that the sharp band near 3480 cm À 1 in as-received natural quartz is associated with Li species but the structure of the defect formed by Li species related to OH is not yet known [2,18]. The sharp band at 3595 cm À 1 , observed at 3581 cm À 1 in IR spectra of synthetic quartz measured at À 196 1C, was assigned to the so-called as-grown OH point defects [19]. As originally proposed by Nuttal and Weil [20] [21].…”