Thermodynamics of plagioclase III: Spontaneous strain at the $$I\overline 1 - P\overline 1$$ phase transition in Ca-rich plagioclase
| Autor: | Ann Graeme-Barber, Ekhard K. H. Salje, Simon A. T. Redfern |
|---|---|
| Rok vydání: | 1988 |
| Předmět: |
chemistry.chemical_classification
Phase transition Overline Condensed matter physics Infinitesimal strain theory Thermodynamics Calcium aluminosilicate engineering.material Anorthite chemistry.chemical_compound chemistry Geochemistry and Petrology Lattice (order) engineering Plagioclase General Materials Science Inorganic compound |
| Zdroj: | Physics and Chemistry of Minerals. 16 |
| ISSN: | 1432-2021 0342-1791 |
| DOI: | 10.1007/bf00203199 |
| Popis: | The lattice parameters of anorthites An98Ab2 and An100 have been measured from 22 to 1100 K. The spontaneous strain arising from the $$I\overline 1 - P\overline 1$$ displacive transition in An98 follows second order Landau behaviour. The spontaneous strain (ɛ s) couples quadratically to the order parameter (Q 0) with ɛ s∝Q 02∝(T c * −T) and T c * =530 K in An98. This is in contrast to the tricritical behaviour observed in pure anorthite. These observations are consistent with a Landau model for the free energy of Ca-rich plagioclases in which Al/Si order and Na content renormalize the fourth order coefficient. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
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