Precipitous weakening of quartz at the α–β phase inversion |
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| Authors: | Brian Lawn David Marshall Rishi Raj Greg Hirth Trevor Page Julie Yeomans |
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| Affiliation: | 1. Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD, USA;2. Departments of Mechanical Engineering and Aerospace Engineering Sciences, University of Colorado, Boulder, CO, USA;3. Materials Science and Engineering Program, University of Colorado, Boulder, CO, USA;4. Earth, Environmental and Planetary Sciences, Brown University, Providence, RI, USA;5. School of Engineering, Newcastle University, Newcastle Upon Tyne, United Kingdom;6. Department of Mechanical Engineering Sciences, University of Surrey, Guildford, United Kingdom |
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| Abstract: | Crystalline quartz has long been identified as among the weakest of abundant crustal minerals. This weakness is particularly evident around the α–β phase inversion at 573°C, in which Si–O bonds undergo a displacive structural transformation from trigonal to hexagonal symmetry. Here we present data using indentation testing methodologies that highlight the precipitous extent of the transformational weakening. Although the indentations are localized over relatively small specimen contact areas, the data quantify the essential deformation and fracture properties of quartz in a predominantly (but not exclusively) compressive stress field, at temperatures and pressures pertinent to conditions in the earth's crust. |
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| Keywords: | alpha-beta transition deformation fracture quartz |
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