Quartz radiation damage

A series of calculations on defect centers induced by radiation damage in alpha-quartz is reported. Ab initio SCF-MO calculations were carried out on a 21 atom cluster, Si50i6 % surrounded by 956 point-ions, designed to simulate alpha-quartz. This two-region approach made it possible to represent the long-range electrostatic effects, present in the crystal, in the SCF-MO cluster. 

Aines, R. D. Rossman, G. R. (1986) Relationships between radiation damage and trace water in zircon, quartz, and topaz. Amer. Mineral., 71,1186-93. 

Figure 8.55. Facing page. Electron radiation damage in quartz, (a) Damage centers produced within a 1-minute exposure to 100-kV electrons, imaged in BF by structure factor contrast, (b) As the damage centers grow during irradiation, they become visible by the strain they produce in the surrounding matrix, (c) On continued irradiation, the strain fields overlap, (d) Eventually, the crystal becomes amorphous, and the strain contrast disappears. (From McLaren and Phakey 1965a.)...

Figure 8.57. WBDF image of a dislocation in electron radiation damaged quartz. The double image of the dislocation is due to the development of amorphous material along the core.

Figure 8.58. BF micrograph showing neutron radiation damage in synthetic quartz (dose 3 x 10 nvt, followed by annealing at 900°C for 16 hours). (From Phakqr 1%7.)...

The rate at which electron radiation damage occurred in neutron-irradiated specimens also varied from one variety of quartz to another. Whereas synthetic quartz (dose Dq) became amorphous after a few seconds of exposure to a focused electron beam, amethyst quartz (dose < Do) was more stable in the electron beam than the sample before neutron irradiation. 

It will also be noted in Table 8.6 that for a dose Dq, crystals of amethyst and citrine can be recovered by annealing at 700°C, whereas the purer crystals (e.g., optical-quality natural and synthetic quartz) require a temperature of 900 to 1,110 C. The reasons for this behavior, and for the influence of neutron irradiation on subsequent electron radiation damage, are not clear. 

When quartz or other suitable mineral detector is deposited into a matrix of minerals containing the radioactive nuclides of the U, U, and Th decay series, and the detector mineral is subject to radiation damage. If the grain had been cleared of all memory of radiation damage prior to deposition, then the extent of damage is a function of the time the detector mineral has been immersed in the radiation-producing matrix. 

Very low concentrations of Cr ( g and ng per kg levels) require, however, long irradiation periods at a high neutron flux, followed by a radiochemical separation. Due to radiation damage induced high pressure built-up, the sealed ampoule can explode. This is avoided by ashing the sera in the quartz vial at a temperature of 450°C, prior to irradiation (Versieck et al., 1978). 

Me Bride EF (1989) Quartz cement in sandstones a review. Earth Science Reviews 26 69-112 McKenzie DP (1981) The variation of temperature with time and hydrocarbon maturation in sedimentary basins formed by extension. Earth and Planetary Science Letters 55 87-98 Meunier JD, Sellier E, Pagel M 1990) Radiation-damage rims in quartz from uranium-bearing sandstones. J Sediment Petrol 60 53-58 Millot G (1964) G6ologie des argiles. Masson et Cie, Paris, p 499... 

Alpha-quartz has many useful properties which lead to its wide use in industry as a glass, ceramic and molecular sieve. However, undoubtedly its most technically important use occurs by virtue of its piezo-electric properties, which allow it to be used as a frequency regulating device in satellites, computers, and the ubiquitous quartz-watch . Unfortunately, it has been found that quartz crystals are susceptible to damage by radiation, and that this is associated with the presence of defects in the crystal lattice. These defects, particularly aluminum and hydrogen, are grown into the crystal and so far have proved impossible to remove. This problem has been the cause of intensive research, which has led to some information on the possible types of defects involved, but has failed to produce details of their geometries, and the way in which they interact. 

Botis, S.M., Pan, Y., Bonli, T., Xu, Y., Sopuck, V., Nokhrin, S. 2006. Natural radiation-induced damage in quartz. II. Implications for uranium mineralization in the Athabasca Basin. Canadian Mineralogist, 44, 1387-1402. 

Photolysis is carried out in an 850-ml. Pyrex glass vessel equipped with a water-cooled quartz probe. The ultraviolet light source is a 450-watt lamp with a Vycor filterf. To reduce the dangers from a possible explosion or eye damage from ultraviolet radiation, the reaction vessel shown in Fig. 5 is contained in a wooden box. 

The organic1 secondary expls were sealed in quartz containers and exposed to a single radiation pulse. None of the expls detonated and subsequent examination of the samples revealed negligible damage... 

In UV-resonance Raman (UVRR) studies, UV lines such as the fourth harmonic (266 nm) of the Nd YAG laser are used for excitation. Under prolonged illumination by focused UV radiation, quartz and other UV-transparent materials tend to become fluorescent. To avoid the use of window materials and to minimize sample damage by strong UV light, several sampling techniques, such as the fluid jet stream technique (60) and the thin-film technique (61), have been developed. 

This report summarizes conventional methods for UV irradiation of air sensitive organometallic compounds at ambient or subambient temperatures. Of the irradiation sources available (l ) the medium pressure Hanovia 450 W arc lamp systems (2) are of moderate price, reliable, and versatile in our experience. Caution Powerful arc lamps can cause eye damage or blindness within seconds and UV protective goggles (available from most scientific supply houses) must be worn. Never look directly at the radiation source. For safety of other workers lamps should be enclosed in a vented box with baffles. If Pyrex transmits enough UV radiation for an efficient reaction, as for photochemical reactions of metal-metal bonded complexes (3), then conventional Schlenkware can be used for photolysis and no special glassware is needed. Since a 2 mm thick wall of Pyrex transmits only 10% of the UV light at 300 nm, UV transparent quartz reaction vessels are often needed for photoreactions of mononuclear organometallic complexes. 

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