Defects and hydrolytic weakening in ?-berlinite AlPO4 a structural analog of quartz

Autor: J. C. Doukhan, Patrick Cordier, B. Boulogne
Rok vydání: 1988
Předmět:
Zdroj: Physics and Chemistry of Minerals. 16
ISSN: 1432-2021
0342-1791
DOI: 10.1007/bf00220693
Popis: Berlinite, AlPO4, is a structural analog of quartz and a number of physical properties are very similar in both materials. It is thus interesting to compare their mechanical properties and investigate the possible role of water. Constant strain rate tests on wet synthetic crystals have been performed at room temperature and at 600 MPa confining pressure. They indicate that $$(000){1 \mathord{\left/ {\vphantom {1 3}} \right. \kern-\nulldelimiterspace} 3}\langle 11\bar 20\rangle $$ is the easy glide system. Detailled investigation of the crystal structure shows that the corresponding a dislocations can glide in such a way that only the weaker Al—O bonds are broken. This explains why this glide system is much more easily activated in berlinite than in quartz. Deformation experiments at higher temperature and at atmospheric pressure clearly show a thermally activated regime. However the actually available crystals are so rich in water that above 300° C the dislocation structure resulting from deformation is completely hidden by water precipitation and coarsening of the as-grown fluid inclusions. Like for wet quartz this later phenomenon generates numerous bubbles and sessile dislocation loops.
Databáze: OpenAIRE
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