Hydrogen and its radiation effects in quartz crystals.
This paper presents near infrared absorption measurements (in the region of 3100-3700 cm(-1)) on quartz crystals to characterize the aluminum- and alkali-related hydroxyl defects in a variety of natural and cultured quartz crystals. Quartz samples were irradiated with an electron beam of 1.75 MeV and a dose of 2 Mrad at 77 K before and after irradiation at 300 K. The alkalis in quartz move under irradiation field only if the sample temperature is about or above 200 K, but the protons move at all temperatures down to 10 K. Therefore, irradiation at 300 K allows movement of both, protons and alkali ions, thus breaking away the aluminum-alkali centers into a mixture of Al-OH (-) and Al-hole centers. The natural quartz crystals have been measured with nearly similar Al and widely varying H-levels. For a similar radiation dose at 300 K, contrary to expectation, a lesser number of Al-OH(-) centers were produced in crystal with higher H-level than the sample with low-H quartz. At the present stage of work, we expect that this may be due to jamming in the kinetics of large number of protons in high-H crystals for steric reasons, which prevents them from reaching Al-sites after irradiation.
Bahadur
H
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Nat. Phys. Lab., New Delhi.