Deformation of wet synthetic quartz

1 The water responsible for the weakening effect is present as isolated water-related point defects, which diffuse readily at temperatures near 500°C. 

2 Under the influence of the applied stress, a dislocation loop can grow by glide only as sufficient HOH diffuses to the growing segment to saturate the newly created core and develop a cloud of hydrolyzed Si—O bonds in the neighborhood of the dislocation in order to reduce the Peierls stress (the fundamental friction to the glide of a dislocation in a perfect crystal) to a very low value. 

The idea that water-related defects might also enhance dislocation climb was suggested by McLaren and Retchford (1969) and included by Griggs (1974) in his microdynamical calculations of the stress-strain curves based on his original hypothesis. 

However, the Griggs hypothesis has been challenged recently in several ways  

1 The observed uptake of water by quartz under conditions of high temperature, pressure, and water fugacity indicates that the diffusivity and/or solubility of water-related point defects in solid solution are much lower than are required by the Griggs model (Gerretsen et al. 1989 Kronenberg, Kirby, and Rossman 1986 Rovetta, Holloway, and Blacic 1986). 

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