Quartz water weakening

McLaren, A. C., Fitz Gerald, J. D., Gerretsen, J. (1989). Dislocation nuclea-tion and multiplication in synthetic quartz relevance to water weakening. Phys. Chem. Minerals, 16, 465-82. 

Ord, A., Hobbs, B. E. (1986). Experimental control of the water-weakening effect in quartz. In Mineral and Rock Deformation Laboratory Studies, The Paterson Volume, Geophysical Monograph 36, edited by B. E. Hobbs H. C. Heard, pp. 51-72. Washington, DC American Geophysical Union. 

In the hydrolytic glide regime, dislocation activity and the mechanism of water weakening depend on the water content of the quartz. High-quality synthetic quartz can be relatively dry ( 100 at. ppm [H[/[Si[), and in these samples the water is accommodated in the quartz lattice by point defects, speciflcally a (4H)si species (i.e., one Si is formally replaced by 4H [91].) Crystals with, say, 1000 at. ppm [H[/[Si[ contain aggregated molecular water in the form of bubbles. These can be fluid inclusions which have no long-range strain fields associated with them, or water... 

Water weakening can occur in olivine, as in quartz [167-170]. It has been suggested by Mackwell et al. [171] that water enhances dtmb mobility, although more detailed explanations are still lacking. Another possibility is that the point defects associated with the addition of water cause enhanced kink nucleation and/or kink diffusion (as described in Section 9.2.3). 

Geologists have found that the mineral quartzite as well as synthetic quartz is softened by water (Griggs and Blacic, 1965). Dry quartz crystals retain then-hardnesses to nearly 1000 °C, but are weakened considerably (nearly an order of magnitude) by the presence of water. Similar weakening is observed for olivine (Mg,Fe)2(Si04) and feldspar (KAlSi3Os). 

Kronenberg A.K., Kirby S.H., Aines R.D., and Rossman G.R. (1986) Solubility and diffu-sional uptake of hydrogen in quartz at high water pressures implications for hydrolytic weakening. /. Geophys. Res. 91(B12), 12723-12744. 

Tullis, J., Yund, R. A. (1989). Hydrolytic weakening of quartz aggregates the role of water and pressure on recovery, Geophys. Res. Letters, 16,1343-6. 

Graetsch, H., Florke, O. W. Miehe, G. (1985). The nature of water in chalcedony and opal-C from Brazilian agate geodes. Physics and Chemistry of Minerals, Vol. 12, pp. 300-306 Grigss, D.T. (1967). Hydrolytic weakening of quartz and other silicates. Geophysical Journal of the Royal Astronomical Society, Vol. 14, pp. 19-32 Hawthorne, F.C. Cerny, R (1977). The alkali-metal positions in Cs-Li beryl. Canadian Mineralogist, Vol. 15, pp. 414-421... 

Kronenberg, A.K. Wolf, G.H. (1990). Fourier transform infrared spectroscopy determinations of intragranular water content in quartz-bearing rocks implications for hydrolytic weakening in the laboratory and within the earth, Techtonophysics, Vol. 172, pp. 255-271... 

In quartz materials grown from seed crystals, the dominant impurity near the seed is molecular H2O. This gives way to OH— as you move away from the seed. It is the presence of such water molecules that is primarily responsible for the hydrolytic weakening in quartz. 

The reaction scheme of Bode [11] was derived by comparison of the X-ray diffraction patterns of the active materials with those for the model compounds. How the 8-Ni(OH)2 in battery electrodes differs from the model compound is discussed in Section 5.3.I.3. In recent years, the arsenal of in situ techniques for electrode characterization has greatly increased. Most of the results confirm Bode s reaction scheme and essentially all the features of the proposed a/y cycle. For instance, recent atomic force microscopy (AFM) of o -Ni(OH)2 shows results consistent with a contraction of the interlayer distance fiom 8.05 to 7.2 A on charge [61-63]. These are the respective interlayer dimensions for the model a-Ni(OH)2 and y-NiOOH compounds. Electrochemical quartz crystal microbalance (ECQM) measurements also confirm the ingress of alkali metal cations into the lattice upon the conversion of a-Ni(OH)2 to y-NiOOH [45,64,65]. However, in situ Raman and surface-enhanced Raman spectroscopy (SERS) results on electrostretching modes that are consistent with a weakening of the O-H bond when compared with results for the model a- and 8-Ni(OH)2 compounds [66]. This has been ascribed to the delocalization of protons by intercalated water and Na ions. Similar effects have been seen in passive films on nickel in borate buffer electrolytes [67]. 

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